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Role of the microenvironment in liver metastasis: from pre- to pro-metastatic
niches
Pnina Brodt*
Departments of Surgery, Medicine, and Oncology McGill University and the McGill University Health
Centre, Montreal, Quebec, Canada
Running Title: The microenvironment in liver metastasis
Key Words: liver metastasis, tumor microenvironment, colon cancer, immunosuppression
This work was made possible by support from the Canadian Institute for Health Research and by a
PSR-SIIRI-843 grant from the Québec Ministère de l'Économie, de l'Innovation et des Exportations.
The author has no conflict of interest to disclose.
* All correspondence should be addressed to:
Dr. Pnina Brodt
The Research Institute of the McGill University Health Centre
The Glen Site, 1001 Décarie Blvd, Room E.02.6220
Montréal, QC, H4A 3J1, Canada
Telephone: (514) 934-1934, Ext. 36692, Fax: (514) 938-7033
Email: [email protected]
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Summary
Liver metastases remain a major barrier to successful management of malignant disease, particularly
for cancers of the gastrointestinal (GI) tract but also for other malignancies such as breast carcinoma
and melanoma. The ability of metastatic cells to survive and proliferate in the liver is determined by
the outcome of complex, reciprocal interactions between the tumor cells and different local resident
subpopulations including the sinusoidal endothelium, stellate, Kupffer and inflammatory cells that are
mediated through cell-cell and cell-extracellular matrix adhesion and the release of soluble factors.
Cross communication between different hepatic resident cells in response to local tissue damage and
inflammation and the recruitment of bone marrow cells further enhance this inter-cellular
communication network. Both resident and recruited cells can play opposing roles in the progression
of metastasis and the balance of these divergent effects determines whether the tumor cells will die,
proliferate and colonize the new site or enter a state of dormancy. Moreover, this delicate balance
can be tilted in favor of metastasis, if factors produced by the primary tumor pre-condition the
microenvironment to form niches of activated resident cells that promote tumor expansion. This
review aims to summarize current knowledge on these diverse interactions and the impact they can
have on the clinical management of hepatic metastases.
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Introduction
Cancer metastasis remains the major challenge to successful management of malignant disease.
The liver is the main site of metastatic disease and a major cause of death from gastrointestinal (GI)
malignancies such as colon, gastric and pancreatic carcinomas, as well as melanoma, breast cancer
and sarcomas (1).
Circulating metastatic cells that enter the liver encounter unique cellular populations. These include
the parenchymal hepatocytes and the non–parenchymal, liver sinusoidal endothelial cells (LSEC),
hepatic stellate cells (HSC), Kupffer cells (KC), dendritic cells, liver associated lymphocytes and
portal fibroblasts. Circulating and bone marrow (BM)-derived immune cells are also recruited to the
liver in response to, and possibly in preparation for invading tumor cells and can affect the final
outcome (reviewed in (2, 3), (see Table 1).
This review summarizes our current understanding of the role of the liver microenvironment in the
growth of hepatic metastases and the reciprocal interactions between metastatic tumor cells and
different liver cell populations that regulate the process.
Pre- and pro metastatic niches drive the progression of liver metastasis.
The process of liver metastasis (LM) has previously been divided into four major phases (detailed in
Table 1) that follow tumor cell entry into the liver (4, 5). Emerging evidence suggests that in addition,
a pre-metastatic phase could set the stage for liver colonization by disseminating tumor cells.
Evidence for pre-metastatic niche formation in the liver:
The term “pre-metastatic niche” was coined to describe a microenvironment in a secondary organ site
that has been rendered permissive to metastatic outgrowth in advance of cancer cell entry through
the activity of circulating factors released by the primary tumor (6) (7, 8). While the dependency of
metastasis on pre-metastatic niches remains controversial and difficult to verify in the clinical setting
(9, 10), it appears that a consensus is emerging on two scores 1. That their existence may have
important implications for the clinical management of metastatic disease and 2. That much can be
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learned from their interrogation about the cellular/molecular changes required to facilitate tumor cell
growth in a distant site, such as the liver. Two recent studies have confirmed their potential relevance
to LM. In a mouse model of metastatic pancreatic ductal adenocarcinoma (PDAC), Costa-Silva et al
showed that PDAC-derived exosomes taken up by hepatic KC, upregulate TGFβ production leading
to increased fibronectin production by HSC and recruitment of BM-derived macrophages. They
identified macrophage-derived MIF as essential for pre-metastatic niche formation and metastasis.
Moreover, in exosomes derived from stage I PDAC patients who later developed LM, MIF levels were
found to be higher than in patients whose tumors did not progress, identifying MIF as a potential
predictor of PDAC LM (11). This group also showed that exosomes from human breast and
pancreatic cancer cell lines that metastasize selectively to the lung (MDA-MB-231) or liver (BxPC-3
and HPAF-II) fused preferentially with fibroblasts and epithelial cells in the lung and KC in the liver,
and this was mediated by the exosomal integrin laminin receptors α6β1and α6β4 and the fibronectin
receptor αvβ5, respectively. In exosome-fused KC, the pro-inflammatory factors S100P and S100A8
were upregulated (Table 1, Fig 1). Significantly, in PDAC patients, a correlation was documented
between the levels of circulating, αv-bearing exosomes and disease stage, suggesting that exosomes
may play a role clinically and their levels and integrin cargo may predict metastases in specific organs
(12). Kowanetz et al reported that tumor-derived GM-CSF could mobilize Ly6C+Ly6G+ myeloid cells
into metastases - enabling niches in the lung and liver and also identified S100A8 as a driving factor
(13). Tumor-derived TIMP-1 was identified as another potential inducer of increased liver
susceptibility to metastasis, acting via hepatic SDF-1 and neutrophil recruitment (14). Interestingly,
S100A8 was identified as a driver of liver pre-metastatic niche formation in several studies (12-15),
suggesting that it may have clinical utility as a predictor of LM.
The stage of primary tumor development at which pre-metastatic niches can be formed is difficult to
assess in the clinical setting. Costa-Silva et al found exosomal MIF upregulation in mice with pre-
tumoral pancreatic lesions and high plasma exosomal MIF levels were also detected in patients with
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stage I PDAC (11), suggesting that they could be formed at very early stages of cancer development.
The potential contribution of circulating cancer cells (CTC) that may be present early in tumor
development and even after resection of the primary tumor (16, 17) is also unknown.
Resident and immune cells can play diverse and opposing roles in the development of liver
metastases.
Host innate resistance mechanism can destroy tumor cells prior to extravasation. Blood-born
cancer cells entering the liver first encounter the LSEC, KC and hepatic NK cells (pit cells) that
together mount the first line of defence (18). Cancer cells entrapped in the sinusoids may undergo
destruction due to mechanical stress and deformation-associated trauma or die due to phagocytosis
by KC or cytolysis by NK cell-released perforin/granzyme (18), (reviewed in (4)). NO, ROS and toxic
radicals released by LSEC in response to local ischemia/reperfusion can contribute to tumor cell
death (19, 20). Release of NO and INFγ by LSEC and NK cells can result in upregulation of tumor
cell Fas and apoptosis (18) that can be augmented by NK and LSEC-derived TNFα (21). TNFα is one
of numerous cytokines and chemokines unleashed by KC in response to inflammation (Table 1) (22).
In addition to causing cell death directly, some of these factors can mobilize and activate additional
innate immune cells such as neutrophils, thereby adding to the local tumoricidal capacity (reviewed in
(23)). In several animal tumor models, including colon cancer, loss of NK cells increased cancer cell
growth in the liver, whereas enhanced NK activity reduced LM (24-26). Indirect evidence also
suggests that susceptibility to NK-mediated immune attack can affect the ability of human cancer
cells to generate LM (27). Circulating neutrophils can also release various factors abundant in their
granules to kill tumor cells (see Table 1) and their cytokines and chemokines can activate the
tumoricidal potential of resident KC and recruit host immune T cells with anti-tumorigenic activities
(reviewed in (28))
Cancer cells can escape these cytotoxic effects by forming clusters with blood or other cancer cells
that shield them from the lethal effects of shear stress or NK-mediated cytotoxicity (reviewed in (29)).
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The release of inflammatory mediators such as IL-1β, TNFα and IL-18 can also initiate a cascade that
facilitates their rapid exit from the vasculature to a less “toxic” microenvironment (see below and Fig
2).
The sinusoidal endothelium actively participates in different phases of metastasis.
Although the rapid inflammatory response initiated by cancer cell entry can lead to cell death, it may
also have a tumor-protective effect by upregulating the expression of LSEC CAM and in this way,
enhance cancer cell adhesion and trans-endothelial migration into the space of Disse, where they can
escape the cytotoxic effects of KC and NK cells (30). Cancer cells can adhere to inflammation -
induced E-selectin, VCAM-1 and ICAM-1, either as single cells or in association with host cells such
as KC or neutrophils (reviewed in (31)). Blockade of this inflammatory cascade was shown to reduce
LM (32-34) and TNFR1 signaling was identified as a major driver of this process (35).
Ultimately, the outcome of these opposing effects on tumor cell survival and progression to the next
phase depends on multiple factors including the expression on the cancer cells of the respective
counter receptors namely, E- selectin ligands sLewa and sLewx and CD44 isoforms (36), (reviewed in
(37)(29)), and VCAM-1 and ICAM-1 counter receptors integrins α4β1 and LFA-1 and Mac-1 (38),
respectively. E-selectin binding triggers a signaling cascade in both tumor cells and LSEC, leading to
diapedesis and trans-endothelial migration (39) and altering gene expression in a tumor-type specific
manner (40). Clinical studies have documented increased expression of E-selectin in and around
CRC liver metastases and elevated soluble E-selectin, ICAM-1 and VCAM-1 levels that correlated
with disease outcome in CRC patients (reviewed in (23)).
LSEC may have other metastasis-promoting functions. LSEC-secreted fibronectin can induce
epithelial-mesenchymal transition (EMT) in CRC cells via integrin α9β1, enhancing ERK signaling and
tumor invasion (41). Human LSEC were shown to induce CRC migration and EMT via MIF (42),
thereby increasing their metastatic potential.
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The LSEC contribute to tumor-induced angiogenesis. A recent study identified Notch1 as a negative
regulator of sinusoidal endothelial cell sprouting into micrometastases and thereby of angiogenesis
and LM (43), raising questions about the advisability of Notch targeting for cancer therapy. Moreover,
LM of different carcinomas, including CRC, can co-opt the sinusoidal endothelium at the tumor-liver
interface, giving rise to a histological growth pattern (GP) termed the “replacement” or “sinusoidal ”GP
that appears to result from tumor cell invasion between LSEC and the matrix in the space of Disse
and is characterized by formation of intra-metastatic vessels that appear continuous with the
sinusoidal vessels (reviewed in (23)). The factors that drive this co-opting mechanism remain to be
identified, but a recent study by Im et al suggests that Ang2 may play a regulatory role (44).
Collectively, the evidence shows that LSEC are not a passive barrier to tumor cell extravasation but
participate actively in the metastatic process. Cancer cell interaction with LSEC can reciprocally alter
the phenotypes of both cell types and this may lead to intravascular tumor cell destruction but can
also promote metastasis through enhanced tumor cell migration and increased angiogenesis (Table
1, Fig 2 and 3).
The role of macrophages is context dependent. KC constitute approximately 10% of all liver cells.
Recent studies suggest that they may be established prenatally and maintained into adulthood,
independently of replenishment from blood monocytes, but in an M-CSF and GM-CSF-dependent
manner (45). They reside mainly in the hepatic sinusoids and are anchored to the endothelium by
long cytoplasmic processes (46) (reviewed in (47)). In their interaction with invading cancer cells, KC
can play diverse and opposing roles, depending on factors such as the stage of the metastatic
process, tumor load and interactions with other immune cells. As discussed, KC can promote
metastasis by orchestrating the pre-metastatic niche. However, tumor-KC interactions can have
opposing effects. Several studies documented a rapid adhesion of tumor cells to KC in the sinusoidal
lumen resulting mainly in tumor cell phagocytosis or apoptosis, within hours of tumor cell entry (47).
This tumoricidal effect may require cooperation with local or recruited NK cells (48) and its efficiency
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in removing cancer cells likely depends on the tumor load (49). An intravital microscopy study (50)
recently revealed that 74% of intra-arterially injected rat colon cancer cells adhered to the KC within 6
hrs., and this was associated with increased liver TNFα and IL-1β levels, consistent with our own
findings (51, 52), and indicative of KC activation. Extensive phagocytosis of tumor cells was observed
within 2 hrs. post injection. Interestingly, while elimination of KC two days prior to tumor injection
increased LM, it had no significant effect up to one week post tumor injection, suggesting that KC
exerted their most potent anti-tumor effect within the first 24 hrs. of tumor cell entry into the liver (50).
A bi-modal effect of KC depletion was also documented in another study of murine CRC and it was
attributed to decreased vascular endothelial growth factor (VEGF) and increased iNOS levels in livers
subjected to late stage KC depletion (53). Indeed, tumor cells that survive the initial tumoricidal
assault by KC can benefit from their pro-tumorigenic functions. Adhesion to KC can facilitate tumor
cell extravasation, among others by sequential activation of endothelial CAM (29, 54). In addition, KC
can produce cytokines and growth factors including IL-6, HGF and VEGF and matrix
metalloproteinases such as MMP-9 and MMP-14 that can accelerate tumor cell invasion into, and
within the parenchymal space, as well as promote tumor cell proliferation and angiogenesis, thereby
enhancing LM (see Table 1 and Figures 2 and 3).
Taken together, the evidence suggests that KC targeting could become an effective anti-metastatic
strategy only within a very narrow window. Limiting KC activity may be beneficial if it could prevent
pre-metastatic niche formation, while enhancing the KC tumoricidal potential using agents such as
INFγ, GM-CSF or muramyl dipeptide may be most effective if achieved before tumor cells enter the
liver in large numbers (47, 55). The contribution of CTC that may be present before liver
micrometastases are established or after surgical resection of the primary tumor (16, 17) to the tumor
load and KC activation is unknown. This multi-faceted role of KC in LM may explain the limited
success to date of KC-targeting interventions (47).
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Importantly, in addition to KC, blood-derived monocytes can also be recruited to the tumor site in
response to local injury and inflammation and differentiate locally into mature CD11bloF4/80hi
macrophages in a CCR2-dependent manner (56). These macrophages can also trigger HSC
activation and fibrogenesis (57), a process important in the early stages of extravascular tumor
expansion (see below).
Macrophages have inherent plasticity and their phenotypes can change within a spectrum of
activation states between the polar M1 and M2 phenotypes (58, 59). M1 macrophages are tumoricidal
due to high NO and TNFα production levels and produce Th1, Th17 and the NK attracting
chemokines CXCL9 and CXCL10 (60). In contrast, M2 macrophages can promote tumor growth
through production of growth factors such as VEGF, EGF, bFGF and TGFβ (61). In addition, M1
macrophages activate Th1-type immune responses that can further amplify M1/killer-type activity
through the production of IFNγ, while M2 macrophages induce regulatory T cells (Treg) and thereby
an immunotolerant microenvironment, through release of TGFβ and IL-10 (62) (Table 1). Evidence
regarding the role of macrophage polarization in LM is scant because macrophages within or around
hepatic metastases have, with few exceptions, not been subtyped. A recent clinical study identified
the M2/M1 ratio in hepatic resections as a correlate of CRC metastasis (63), implicating M2
macrophages in the clinical disease. Furthermore, F4/80 – the cell surface marker frequently used to
identify KC is also expressed on recruited monocytes, and strategies used to eliminate macrophages
in vivo are not KC-specific. The source and identities of macrophages in many published studies
remain therefore to be verified. As immune-editing of the tumor microenvironment and the conversion
of tumor associated (TAM) M2 macrophages to M1 killer macrophages are emerging as potentially
relevant anti-cancer strategies (62), further characterization of both the source and the status of
macrophage populations involved in LM will become critical.
The Neutrophils: a double-edged sword. Neutrophils are part of the innate immune response to
pathogens and are also rapidly activated in response to invading cancer cells (28). BM-derived
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neutrophils are mobilized to sites of inflammation or cancer via their cell surface receptor CXCR2 and
in response to chemokines and cytokines (Table 1) secreted by activated macrophges, endothelial
cells or the tumor cells (reviewed in (28)). At the tumor site, the neutrophils can exert opposing effects
that depend on the inflammatory/immune context (reviewed in (64)). They can release cytolytic
factors (Detailed in Table 1) or inhibit tumor growth indirectly, via recruitment of CD8+ cytotoxic T cells
and macrophages. This may require direct contact with the tumor cells (65) such as can occur within
the liver sinusoidal lumen (66, 67).
On the other hand, neutrophils can be mobilized into pre-metastatic niches in the liver in response to
S100A8 and S100A9 (7) and were shown to contribute to niche formation in an orthotropic colon
carcinoma model (68). Moreover, in the vascular lumen, the physical interaction with tumor cells that
could lead to tumor cell kill may, alternatively, anchor circulating tumor cells to the vascular
endothelium and enhance their migration into the extravascular space. Tumor-derived cytokines such
as IL-8 induce expression of integrins such as CD11b/CD18 on the neutrophils, increasing their
adhesion to tumor cells via the counter receptor ICAM-1 and facilitating trans-endothelial migration,
as shown in murine melanoma and lung carcinoma models (67, 69). Tumor cell entrapment in the
sinusoids can also be mediated by neutrophil-produced extracellular (DNA) traps (NETs), resulting in
increased tumor retention in the sinusoids, enhanced tumor cell adhesion, proliferation, migration and
invasion and increased LM (70, 71). Neutrophils can also release ECM-degrading proteinases such
as MMP-8, MMP-9, elastase and cathepsin G, thereby increasing tumor invasion (65) and can
promote angiogenesis through the release of VEGF (Table 1 and Figures 2 and 3).
Moreover, a TGFβ-mediated neutrophil polarization that alters the phenotype of tumor-associated
neutrophils from tumor inhibitory (N1) to tumor promoting (N2) was recently described (72). TGFβ
produced by M2 macrophages may contribute to this process (reviewed in (59)). The contribution of
polarized neutrophils to LM remains, however, to be confirmed.
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Clinical studies implicate neutrophils in tumor promotion. With few exceptions, elevated circulating
neutrophil counts or neutrophil-to-lymphocyte ratios were associated with poorer outcomes and
distant metastases in patients with various epithelial malignancies (73), including carcinomas of the
GI tract. High neutrophil counts may also be associated with increased resistance to therapy (64,
73). The 5-year survival for CRC patients undergoing hepatic resections that had neutrophil-to-
lymphocyte ratios greater than 5 was worse than for those with normal ratios (74). However, high
neutrophil infiltration into the tumor site may be a consequence of advanced tumor stage (and
therefore poorer prognosis) rather than its cause.
Hepatic stellate cells orchestrate a pro-metastatic microenvironment that is required for
transition from the avascular to the vascular stage of metastasis.
The HSC orchestrate the characteristic fibrogenic response of the liver to injury. Normally quiescent
in the space of Disse (75), they are activated (aHSC), in response to liver damage and inflammatory
stimuli, acquire a myofibroblast-like phenotype (α-SMA+) and produce ECM rich in collagens I and IV
(75, 76). Chemokines and cytokines released by aHSC (Table 1) also recruit inflammatory/immune
cells (77, 78), thereby shaping the immune microenvironment.
In addition to their role in pre-metastatic niche formation (above), HSC can orchestrate a pro-
metastatic niche following tumor extravasation. In response to growth factors and inflammatory
mediators (detailed in Table 1), HSC are activated (75) and can trigger a process akin to the early
events in liver repair. This was observed in animal models (4) and is also evidenced by the increased
production of collagen IV in and around hepatic metastases in clinical specimens (79). Macrophages,
hepatocytes and LSEC contribute to this process by releasing TGFβ and/or TNFα (57). In turn, aHSC
–derived pro-angiogenic factors such as VEGF and angiopoietin-1 (80, 81) initiate angiogenesis (3)
and this is enhanced by HSC-derived MMPs that facilitate endothelial cell migration and tumor
invasion (23, 75) (reviewed in (5, 82)) (Table 1, Fig 2).
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Several lines of evidence confirm the essential role of HSC in LM. Olaso et al showed that
myofibroblasts infiltrating into avascular micrometastases of B16 melanoma cells induced a stromal
response favorable to angiogenesis that preceded endothelial cell recruitment and was followed by
co-localization of myofibroblasts and endothelial cells within angiogenic structures (83),(84). HSC and
macrophage recruitment into metastatic sites and subsequent angiogenesis were shown to be
CCR2/CCL2-dependent (85). More recently, Eveno et al (86) using immunofluorescence, showed
that 9 days post injection of CRC LS174 cells into SCID mice, the hepatic micrometastases consisted
of proliferating cancer cells, a well-organized network of aHSC and laminin deposits but no vascular
network. As the LM grew, an organized vascular network appeared and laminin co-localized with
CD31+ endothelial cells. Co-injection of tumor cells and aHSC enhanced metastasis. Moreover,
analysis of LM from CRC patients revealed a surface marker expression pattern similar to that
observed in the co-injection studies.
Recently, suppression of TGFβ receptor II signalling by QGAP1 was shown to prevent HSC activation
and IQGAP1 downregulation was observed in myofibroblasts associated with human CRC LM,
consistent with their activation in this context (87). Furthermore, α-SMA+ cells whose presence
correlated with the degree of fibrous stroma were identified in LM of colon, gastric and pancreatic
adenocarcinomas (88).
The importance of HSC to metastatic niche formation and their role in primary liver cancer (89) have
raised interest in HSC-targeting as an anti-cancer/anti-metastatic strategy. There is little direct
evidence that such an approach can succeed, due partially to the present lack of agents that
specifically target HSC, without toxicity. Indirect evidence from a rat model of cholangiocarcinoma
(90) and pancreatic stellate cell targeting in a PDAC model (82) suggest a potential therapeutic
benefit, but this remains to be verified. Of note, portal fibroblasts and BM derived fibrocytes (91) can
also contribute to the stromal response. Liver-invading cancer cells located in portal tracts and unable
to activate HSC may engage portal tract fibroblasts that produce IL-8, a chemokine involved in
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invasion and angiogenesis (92). Specific targeting of HSC may therefore not be sufficient to deprive
metastatic cells of a growth-promoting stroma.
Hepatocytes can promote metastasis directly and indirectly.
The role of the parenchymal hepatocytes in LM is not well understood. Tumor cell adhesion to
hepatocytes was identified as one of the earliest events in LM formation and a correlate of the
metastatic potential (93, 94). Desmosomes (95), integrins αv, α6 and β1 that bind to hepatocyte ECM
(94), osteopontin binding via counter receptors CD44 and integrin αv (96) and claudins (97, 98) were
all implicated. Adhesion of human CRC cells to hepatocyte-derived ECM was shown to upregulate
the expression of genes involved in tumor cell survival, motility and proliferation, in particular EGF
family members implicated in LM (99) such as AREG, EGFR, HBEGF and erbB2 and stem cell
markers CD133 (PROM1) and LGR5 (100), suggesting that CRC adhesion to hepatocytes ECM
induces autocrine growth-promoting mechanisms for tumor expansion. Tumor cell adhesion to
hepatocytes can have other consequences. The FasL/FLICE-like inhibitory protein on murine MC38
cells was shown to induce apoptosis in hepatocytes by activating Fas signaling and this destructive
process created a niche for tumor expansion (101). Furthermore, hepatocytes produce several
growth factors including IGF-I (102). As we have shown, blockade of IGF-I signaling in metastatic
tumor cells could inhibit LM (103-105). Other factors include the hepatocyte growth factor-like
protein/macrophage stimulating protein (HGFL) that can enhance tumor growth, motility and invasion
via the Ron receptor (106), heregulin - a ligand of ErbB3 shown to enhance integrin αvβ5-mediated
cell migration and erbB3/erbB2 signaling in human CRC cells (107) and the pro-angiogenic factor
bFGF (108) .
The clinical relevance of tumor-hepatocyte interactions is not clear. Three different histological GPs
have been identified in LM specimens namely, the desmoplastic, pushing, and replacement GPs. The
latter two are characterized by close tumor-hepatocyte proximity (23). Whether or not direct adhesion
between metastatic cancer cells and hepatocytes influences the eventual GP of CRC LM is not
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known. Blocking tumor-hepatocyte interactions could have beneficial anti-metastatic effects, as
recently demonstrated by Tabaries et al (109).
An immunosuppressive microenvironment facilitates metastatic expansion.
Tumor cells can activate specific T-cell mediated immune responses that curtail tumor expansion
through various mechanisms (reviewed in (110)). However, tumor cells can evade T-cell mediated kill
among others, by giving rise to and/or recruiting immunosuppressive cells, such as myeloid derived
suppressor cells (MDSC) and Treg that alter the immune landscape, inducing a state of immune-
tolerance, permissive to tumor expansion (reviewed in (111)).
Role of Treg: Treg cells may be thymically derived (natural, nTregs) or induced from naïve CD4+ T
cell precursors (iTreg) in response to IL-10 and TGFβ. They exert an immunosuppressive effect by
different mechanisms that result in the inhibition of an effective, anti-tumorigenic T cell response
(reviewed in (112)). Although high Treg levels were documented in the blood and local tumor sites of
patients with various epithelial cancers (e.g. (113)), relatively little is known about their role in LM.
Connolly et al, using models of early, pre-invasive pancreatic neoplasia and advanced colorectal
cancer showed that Tregs accelerated the development of LM (114). We recently documented the
accumulation of Treg around colon carcinoma MC38 liver micrometastases and showed that this was
TNFR2 dependent (35).
Intriguingly, in fifty seven colon cancer specimens from patients undergoing chemo- or
chemoimmunotherapy, higher Treg infiltration scores were associated with a better prognosis and a
better outcome (115). However, the relationship between Treg accumulation in the primary tumors
and in the corresponding liver metastases has not been examined. While Treg-targeting strategies
are in development (116, 117) (reviewed in (111)), their potential therapeutic benefit for LM has not
yet been examined.
The Role of MDSC. The MDSC are a heterogeneous population of myeloid cells that can be of
monocytic (Mo-MDSC, CD11b+Ly6C+) or granulocytic (G-MDSC, CD11b+Ly6G+) lineages (118). In
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humans, MDSCs are CD33+ and/or CD11b+ and HLA-DR- (119). Under normal physiological
conditions, BM-derived, immature myeloid cells differentiate into mature granulocytes or monocytes,
able to mediate host innate immune responses in the target tissue. However, in the tumor
microenvironment, these precursors do not mature and exert immunosuppressive and tumor-
promoting effects (120). Although they express granulocyte and monocyte surface markers, these
cells have been characterized based on functional criteria namely, their immunosuppressive
capability (118, 121). An increase in circulating MDSC in cancer patients and their recruitment into
tumor sites has been documented (118, 122, 123).
In the liver, MDSCs can be recruited to the metastases through chemokines such as CXCL1 and
CXCL2 produced by LSEC and KC or by activated HSC (78). There, they can promote tumor growth
by inducing immunosuppression (124), producing arginase (118) and increasing Treg numbers (125)
(Table 1 and Fig 2). Clinical and experimental evidence confirm their role in metastasis (126).
Recruitment of tumor-promoting myeloid cells into CRC LM has recently been documented and their
depletion was shown to result in a marked reduction in LM (127). We recently reported that MDSC
accumulate in hepatic micrometastases of MC38 cells within days of tumor cell injection and
documented a relative preponderance of Ly6Chigh cells (the more suppressive, arginase-high subtype
(128)). We also identified CD33+HLA-DR-TNFR2+ myeloid cells in the periphery of hepatic
metastases from CRC patients, implicating MDSC in the clinical disease (35).
Several strategies are being developed to selectively eliminate MDSC, including pharmacological
induction of MDSC differentiation, inhibition of MDSC expansion from BM precursors or blockade of
their function (129). However, some of the drugs developed are not MDSC-specific or their long term
administration is not possible due to toxicity (129). Their translational potential remains therefore to
be verified.
Conclusion
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Cancer cells entering the liver encounter a unique and complex microenvironment. Parenchymal and
non-parenchymal liver cells, as well as recruited inflammatory and immune cells participate in the
response to invading tumor cells and may inhibit or favor the progression of metastasis. The factors
that determine the outcome of these opposing effects and the pattern of growth of the metastases are
not yet well understood. This duality of function and the shifts in the types of cells and mediators
involved at different stages of the metastatic process render the attempts to target specific cellular
interactions in the microenvironment extremely challenging and may explain the slow progress, to
date, in identifying agents that can successfully and specifically inhibit metastatic disease. With the
advent of genomic profiling for personalized cancer treatment and the increased availability of
surgically resected LM for cellular/molecular interrogation, our understanding of the relationship
between the genetic background and clinical history of the patient, the genomic/transcriptomic profile
of the cancer cells and the type of response mounted by the microenvironment may improve, opening
new avenues for prevention and/or treatment of liver metastatic disease.
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Acknowledgements
The author is indebted to Dr. Janusz Rak (McGill University Health Center) for insightful editorial
comments and to Simon Milette for the superb artistic rendering of the metastatic niches of the liver
and for his help with the Table. Studies by the author’s group cited in this manuscript were supported
by grants from the Canadian Institute for Health Research and by a PSR-SIIRI-843 grant from the
Québec Ministère de l'Économie, de l'Innovation et des Exportations.
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REFERENCES
1. Hess KR, Varadhachary GR, Taylor SH, Wei W, Raber MN, Lenzi R, et al. Metastatic patterns in adenocarcinoma. Cancer. 2006;106(7):1624-33.
2. Kmiec Z. Cooperation of liver cells in health and disease. Adv Anat Embryol Cell Biol. 2001;161:III-XIII, 1-151.
3. Smedsrod B, Le Couteur D, Ikejima K, Jaeschke H, Kawada N, Naito M, et al. Hepatic sinusoidal cells in health and disease: update from the 14th International Symposium. Liver Int. 2009;29(4):490-501.
4. Vidal-Vanaclocha F. The Prometastatic Microenvironment of the Liver. Cancer Microenvironment. 2008;1(1):113-29.
5. Vidal-Vanaclocha F. The Tumor Microenvironment at Different Stages of Hepatic Metastasis. In: Brodt P, editor. Liver Metastasis: Biology and Clinical Management. Dordrecht: Springer Science+Business Media B.V.,; 2011. p. 1 online resource.
6. Kaplan RN, Riba RD, Zacharoulis S, Bramley AH, Vincent L, Costa C, et al. VEGFR1-positive haematopoietic bone marrow progenitors initiate the pre-metastatic niche. Nature. 2005;438(7069):820-7.
7. Hiratsuka S, Watanabe A, Aburatani H, Maru Y. Tumour-mediated upregulation of chemoattractants and recruitment of myeloid cells predetermines lung metastasis. Nat Cell Biol. 2006;8(12):1369-75.
8. Hiratsuka S, Watanabe A, Sakurai Y, Akashi-Takamura S, Ishibashi S, Miyake K, et al. The S100A8-serum amyloid A3-TLR4 paracrine cascade establishes a pre-metastatic phase. Nat Cell Biol. 2008;10(11):1349-55.
9. Psaila B, Lyden D. The metastatic niche: adapting the foreign soil. Nat Rev Cancer. 2009;9(4):285-93.
10. Sceneay J, Smyth MJ, Moller A. The pre-metastatic niche: finding common ground. Cancer Metastasis Rev. 2013;32(3-4):449-64.
11. Costa-Silva B, Aiello NM, Ocean AJ, Singh S, Zhang H, Thakur BK, et al. Pancreatic cancer exosomes initiate pre-metastatic niche formation in the liver. Nat Cell Biol. 2015;17(6):816-26.
12. Hoshino A, Costa-Silva B, Shen TL, Rodrigues G, Hashimoto A, Tesic Mark M, et al. Tumour
Research. on June 29, 2021. © 2016 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. Author Manuscript Published OnlineFirst on October 19, 2016; DOI: 10.1158/1078-0432.CCR-16-0460
http://clincancerres.aacrjournals.org/
-
19
exosome integrins determine organotropic metastasis. Nature. 2015;527(7578):329-35.
13. Kowanetz M, Wu X, Lee J, Tan M, Hagenbeek T, Qu X, et al. Granulocyte-colony stimulating factor promotes lung metastasis through mobilization of Ly6G+Ly6C+ granulocytes. Proc Natl Acad Sci U S A. 2010;107(50):21248-55.
14. Seubert B, Grunwald B, Kobuch J, Cui H, Schelter F, Schaten S, et al. Tissue inhibitor of metalloproteinases (TIMP)-1 creates a premetastatic niche in the liver through SDF-1/CXCR4-dependent neutrophil recruitment in mice. Hepatology. 2015;61(1):238-48.
15. Zhang Y, Davis C, Ryan J, Janney C, Peña MMO. Development and characterization of a reliable mouse model of colorectal cancer metastasis to the liver. Clinical & Experimental Metastasis. 2013;30(7):903-18.
16. Bork U, Rahbari NN, Scholch S, Reissfelder C, Kahlert C, Buchler MW, et al. Circulating tumour cells and outcome in non-metastatic colorectal cancer: a prospective study. Br J Cancer. 2015;112(8):1306-13.
17. Tsai WS, Chen JS, Shao HJ, Wu JC, Lai JM, Lu SH, et al. Circulating Tumor Cell Count Correlates with Colorectal Neoplasm Progression and Is a Prognostic Marker for Distant Metastasis in Non-Metastatic Patients. Sci Rep. 2016;6:24517.
18. Braet F, Nagatsuma K, Saito M, Soon L, Wisse E, Matsuura T. The hepatic sinusoidal endothelial lining and colorectal liver metastases. World Journal of Gastroenterology : WJG. 2007;13(6):821-5.
19. Wang HH, McIntosh AR, Hasinoff BB, Rector ES, Ahmed N, Nance DM, et al. B16 melanoma cell arrest in the mouse liver induces nitric oxide release and sinusoidal cytotoxicity: a natural hepatic defense against metastasis. Cancer Res. 2000;60(20):5862-9.
20. Yanagida H, Kaibori M, Yoshida H, Habara K, Yamada M, Kamiyama Y, et al. Hepatic ischemia/reperfusion upregulates the susceptibility of hepatocytes to confer the induction of inducible nitric oxide synthase gene expression. Shock. 2006;26(2):162-8.
21. Hehlgans T, Pfeffer K. The intriguing biology of the tumour necrosis factor/tumour necrosis factor receptor superfamily: players, rules and the games. Immunology. 2005;115(1):1-20.
22. Ramadori G, Moriconi F, Malik I, Dudas J. Physiology and pathophysiology of liver inflammation, damage and repair. J Physiol Pharmacol. 2008;59 Suppl 1:107-17.
23. Van den Eynden GG, Majeed AW, Illemann M, Vermeulen PB, Bird NC, Hoyer-Hansen G, et al. The multifaceted role of the microenvironment in liver metastasis: biology and clinical implications. Cancer Res. 2013;73(7):2031-43.
24. Bertin S, Neves S, Gavelli A, Baque P, Brossette N, Simoes S, et al. Cellular and molecular events associated with the antitumor response induced by the cytosine deaminase/5-fluorocytosine suicide gene therapy system in a rat liver metastasis model. Cancer Gene Ther. 2007;14(10):858-66.
25. Takehara T, Uemura A, Tatsumi T, Suzuki T, Kimura R, Shiotani A, et al. Natural killer cell-mediated ablation of metastatic liver tumors by hydrodynamic injection of IFNalpha gene to mice. Int J Cancer. 2007;120(6):1252-60.
Research. on June 29, 2021. © 2016 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. Author Manuscript Published OnlineFirst on October 19, 2016; DOI: 10.1158/1078-0432.CCR-16-0460
http://clincancerres.aacrjournals.org/
-
20
26. Tatsumi T, Takehara T, Yamaguchi S, Sasakawa A, Miyagi T, Jinushi M, et al. Injection of IL-12 gene-transduced dendritic cells into mouse liver tumor lesions activates both innate and acquired immunity. Gene Ther. 2007;14(11):863-71.
27. Pfister K, Radons J, Busch R, Tidball JG, Pfeifer M, Freitag L, et al. Patient survival by Hsp70 membrane phenotype: association with different routes of metastasis. Cancer. 2007;110(4):926-35.
28. Spicer J, Brodt P, Ferri LE. Role of Inflammation in the Early Stages of Liver Metastasis. In: P. B, editor. Liver Metastasis: Biology and Clinical Management. New York: Springer 2011. p. 155-85
29. Paschos KA, Majeed AW, Bird NC. Natural history of hepatic metastases from colorectal cancer - pathobiological pathways with clinical significance. World Journal of Gastroenterology : WJG. 2014;20(14):3719-37.
30. Glinskii OV, Huxley VH, Glinsky GV, Pienta KJ, Raz A, Glinsky VV. Mechanical Entrapment Is Insufficient and Intercellular Adhesion Is Essential for Metastatic Cell Arrest in Distant Organs. Neoplasia (New York, NY). 2005;7(5):522-7.
31. Brodt P. Role of the Host Inflammatory Response in Colon Carcinoma Initiation, Progression and Liver Metastasis. In: Beauchemin N, Huot J, editors. Metastasis of Colorectal Cancer. New York: Springer; 2010. p. 289-319.
32. Jiao S-F, Sun K, Chen X-J, Zhao X, Cai N, Liu Y-J, et al. Inhibition of tumor necrosis factor alpha reduces the outgrowth of hepatic micrometastasis of colorectal tumors in a mouse model of liver ischemia-reperfusion injury. Journal of Biomedical Science. 2014;21(1):1-.
33. Khatib AM, Fallavollita L, Wancewicz EV, Monia BP, Brodt P. Inhibition of hepatic endothelial E-selectin expression by C-raf antisense oligonucleotides blocks colorectal carcinoma liver metastasis. Cancer Res. 2002;62(19):5393-8.
34. Yoshimoto K, Tajima H, Ohta T, Okamoto K, Sakai S, Kinoshita JUN, et al. Increased E-selectin in hepatic ischemia-reperfusion injury mediates liver metastasis of pancreatic cancer. Oncology Reports. 2012;28(3):791-6.
35. Ham B, Wang N, D'Costa Z, Fernandez MC, Bourdeau F, Auguste P, et al. TNF Receptor-2 Facilitates an Immunosuppressive Microenvironment in the Liver to Promote the Colonization and Growth of Hepatic Metastases. Cancer Res. 2015;75(24):5235-47.
36. Elliott VA, Rychahou P, Zaytseva YY, Evers BM. Activation of c-Met and Upregulation of CD44 Expression Are Associated with the Metastatic Phenotype in the Colorectal Cancer Liver Metastasis Model. PLoS ONE. 2014;9(5):e97432.
37. Witz IP. The selectin-selectin ligand axis in tumor progression. Cancer Metastasis Rev. 2008;27(1):19-30.
38. Greenwald E, Yuki K. A translational consideration of intercellular adhesion molecule-1 biology in the perioperative setting. Transl Perioper Pain Med. 2016;1(2):17-23.
39. Tremblay PL, Huot J, Auger FA. Mechanisms by which E-selectin regulates diapedesis of colon cancer cells under flow conditions. Cancer Res. 2008;68(13):5167-76.
Research. on June 29, 2021. © 2016 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. Author Manuscript Published OnlineFirst on October 19, 2016; DOI: 10.1158/1078-0432.CCR-16-0460
http://clincancerres.aacrjournals.org/
-
21
40. Aychek T, Miller K, Sagi-Assif O, Levy-Nissenbaum O, Israeli-Amit M, Pasmanik-Chor M, et al. E-selectin regulates gene expression in metastatic colorectal carcinoma cells and enhances HMGB1 release. Int J Cancer. 2008;123(8):1741-50.
41. Ou J, Peng Y, Deng J, Miao H, Zhou J, Zha L, et al. Endothelial cell-derived fibronectin extra domain A promotes colorectal cancer metastasis via inducing epithelial-mesenchymal transition. Carcinogenesis. 2014;35(7):1661-70.
42. Hu CT, Guo LL, Feng N, Zhang L, Zhou N, Ma LL, et al. MIF, secreted by human hepatic sinusoidal endothelial cells, promotes chemotaxis and outgrowth of colorectal cancer in liver prometastasis. Oncotarget. 2015;6(26):22410-23.
43. Banerjee D, Hernandez SL, Garcia A, Kangsamaksin T, Sbiroli E, Andrews J, et al. Notch suppresses angiogenesis and progression of hepatic metastases. Cancer Res. 2015;75(8):1592-602.
44. Im JH, Tapmeier T, Balathasan L, Gal A, Yameen S, Hill S, et al. G-CSF rescues tumor growth and neo-angiogenesis during liver metastasis under host angiopoietin-2 deficiency. Int J Cancer. 2013;132(2):315-26.
45. Yona S, Kim KW, Wolf Y, Mildner A, Varol D, Breker M, et al. Fate mapping reveals origins and dynamics of monocytes and tissue macrophages under homeostasis. Immunity. 2013;38(1):79-91.
46. Bouwens L, Baekeland M, De Zanger R, Wisse E. Quantitation, tissue distribution and proliferation kinetics of Kupffer cells in normal rat liver. Hepatology. 1986;6(4):718-22.
47. van der Bij GJ, Oosterling SJ, Meijer S, Beelen RH, van Egmond M. Therapeutic potential of Kupffer cells in prevention of liver metastases outgrowth. Immunobiology. 2005;210(2-4):259-65.
48. Timmers M, Vekemans K, Vermijlen D, Asosingh K, Kuppen P, Bouwens L, et al. Interactions between rat colon carcinoma cells and Kupffer cells during the onset of hepatic metastasis. Int J Cancer. 2004;112(5):793-802.
49. Bayon LG, Izquierdo MA, Sirovich I, van Rooijen N, Beelen RH, Meijer S. Role of Kupffer cells in arresting circulating tumor cells and controlling metastatic growth in the liver. Hepatology. 1996;23(5):1224-31.
50. Matsumura H, Kondo T, Ogawa K, Tamura T, Fukunaga K, Murata S, et al. Kupffer cells decrease metastasis of colon cancer cells to the liver in the early stage. Int J Oncol. 2014;45(6):2303-10.
51. Khatib AM, Auguste P, Fallavollita L, Wang N, Samani A, Kontogiannea M, et al. Characterization of the host proinflammatory response to tumor cells during the initial stages of liver metastasis. Am J Pathol. 2005;167(3):749-59.
52. Khatib AM, Kontogiannea M, Fallavollita L, Jamison B, Meterissian S, Brodt P. Rapid induction of cytokine and E-selectin expression in the liver in response to metastatic tumor cells. Cancer Res. 1999;59(6):1356-61.
53. Wen SW, Ager EI, Christophi C. Bimodal role of Kupffer cells during colorectal cancer liver metastasis. Cancer Biology & Therapy. 2013;14(7):606-13.
Research. on June 29, 2021. © 2016 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. Author Manuscript Published OnlineFirst on October 19, 2016; DOI: 10.1158/1078-0432.CCR-16-0460
http://clincancerres.aacrjournals.org/
-
22
54. Jessup JM, Samara R, Battle P, Laguinge LM. Carcinoembryonic antigen promotes tumor cell survival in liver through an IL-10-dependent pathway. Clin Exp Metastasis. 2004;21(8):709-17.
55. Asao T, Shibata HR, Batist G, Brodt P. Eradication of hepatic metastases of carcinoma H-59 by combination chemoimmunotherapy with liposomal muramyl tripeptide, 5-fluorouracil, and leucovorin. Cancer Res. 1992;52(22):6254-7.
56. Tosello-Trampont A-C, Landes SG, Nguyen V, Novobrantseva TI, Hahn YS. Kuppfer Cells Trigger Nonalcoholic Steatohepatitis Development in Diet-induced Mouse Model through Tumor Necrosis Factor-α Production. The Journal of Biological Chemistry. 2012;287(48):40161-72.
57. Dey A, Allen J, Hankey-Giblin PA. Ontogeny and Polarization of Macrophages in Inflammation: Blood Monocytes Versus Tissue Macrophages. Frontiers in Immunology. 2014;5:683.
58. Murray PJ, Allen JE, Biswas SK, Fisher EA, Gilroy DW, Goerdt S, et al. Macrophage activation and polarization: nomenclature and experimental guidelines. Immunity. 2014;41(1):14-20.
59. Schouppe E, De Baetselier P, Van Ginderachter JA, Sarukhan A. Instruction of myeloid cells by the tumor microenvironment: Open questions on the dynamics and plasticity of different tumor-associated myeloid cell populations. Oncoimmunology. 2012;1(7):1135-45.
60. Galdiero MR, Bonavita E, Barajon I, Garlanda C, Mantovani A, Jaillon S. Tumor associated macrophages and neutrophils in cancer. Immunobiology. 2013;218(11):1402-10.
61. Mills CD. Anatomy of a discovery: m1 and m2 macrophages. Front Immunol. 2015;6:212.
62. Mills CD, Lenz LL, Harris RA. A Breakthrough: Macrophage-Directed Cancer Immunotherapy. Cancer Res. 2016.
63. Cui YL, Li HK, Zhou HY, Zhang T, Li Q. Correlations of tumor-associated macrophage subtypes with liver metastases of colorectal cancer. Asian Pac J Cancer Prev. 2013;14(2):1003-7.
64. Sionov RV, Fridlender ZG, Granot Z. The Multifaceted Roles Neutrophils Play in the Tumor Microenvironment. Cancer Microenviron. 2015;8(3):125-58.
65. Sionov RV, Fridlender ZG, Granot Z. The Multifaceted Roles Neutrophils Play in the Tumor Microenvironment. Cancer Microenvironment. 2014;8(3):125-58.
66. McDonald B, Spicer J, Giannais B, Fallavollita L, Brodt P, Ferri LE. Systemic inflammation increases cancer cell adhesion to hepatic sinusoids by neutrophil mediated mechanisms. Int J Cancer. 2009;125(6):1298-305.
67. Spicer JD, McDonald B, Cools-Lartigue JJ, Chow SC, Giannias B, Kubes P, et al. Neutrophils promote liver metastasis via Mac-1-mediated interactions with circulating tumor cells. Cancer Res. 2012;72(16):3919-27.
68. Yamamoto M, Kikuchi H, Ohta M, Kawabata T, Hiramatsu Y, Kondo K, et al. TSU68 prevents liver metastasis of colon cancer xenografts by modulating the premetastatic niche. Cancer Res. 2008;68(23):9754-62.
Research. on June 29, 2021. © 2016 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. Author Manuscript Published OnlineFirst on October 19, 2016; DOI: 10.1158/1078-0432.CCR-16-0460
http://clincancerres.aacrjournals.org/
-
23
69. Huh SJ, Liang S, Sharma A, Dong C, Robertson GP. Transiently entrapped circulating tumor cells interact with neutrophils to facilitate lung metastasis development. Cancer Res. 2010;70(14):6071-82.
70. Cools-Lartigue J, Spicer J, McDonald B, Gowing S, Chow S, Giannias B, et al. Neutrophil extracellular traps sequester circulating tumor cells and promote metastasis. J Clin Invest. 2013;123(8):3446-58.
71. Tohme S, Yazdani HO, Al-Khafaji AB, Chidi AP, Loughran P, Mowen K, et al. Neutrophil Extracellular Traps Promote the Development and Progression of Liver Metastases after Surgical Stress. Cancer Res. 2016;76(6):1367-80.
72. Fridlender ZG, Sun J, Kim S, Kapoor V, Cheng G, Ling L, et al. Polarization of tumor-associated neutrophil phenotype by TGF-beta: "N1" versus "N2" TAN. Cancer Cell. 2009;16(3):183-94.
73. Donskov F. Immunomonitoring and prognostic relevance of neutrophils in clinical trials. Semin Cancer Biol. 2013;23(3):200-7.
74. Halazun KJ, Aldoori A, Malik HZ, Al-Mukhtar A, Prasad KR, Toogood GJ, et al. Elevated preoperative neutrophil to lymphocyte ratio predicts survival following hepatic resection for colorectal liver metastases. Eur J Surg Oncol. 2008;34(1):55-60.
75. Friedman SL. Hepatic stellate cells: protean, multifunctional, and enigmatic cells of the liver. Physiol Rev. 2008;88(1):125-72.
76. Gressner AM, Bachem MG. Molecular mechanisms of liver fibrogenesis--a homage to the role of activated fat-storing cells. Digestion. 1995;56(5):335-46.
77. Muhanna N, Doron S, Wald O, Horani A, Eid A, Pappo O, et al. Activation of hepatic stellate cells after phagocytosis of lymphocytes: A novel pathway of fibrogenesis. Hepatology. 2008;48(3):963-77.
78. Zhao W, Zhang L, Xu Y, Zhang Z, Ren G, Tang K, et al. Hepatic stellate cells promote tumor progression by enhancement of immunosuppressive cells in an orthotopic liver tumor mouse model. Lab Invest. 2014;94(2):182-91.
79. Burnier JV, Wang N, Michel RP, Hassanain M, Li S, Lu Y, et al. Type IV collagen-initiated signals provide survival and growth cues required for liver metastasis. Oncogene. 2011;30(35):3766-83.
80. Copple BL, Bai S, Burgoon LD, Moon J-OK. Hypoxia-inducible Factor-1α Regulates Expression of Genes in Hypoxic Hepatic Stellate Cells Important for Collagen Deposition and Angiogenesis. Liver international : official journal of the International Association for the Study of the Liver. 2011;31(2):230-44.
81. Taura K, De Minicis S, Seki E, Hatano E, Iwaisako K, Osterreicher CH, et al. Hepatic Stellate Cells Secrete Angiopoietin 1 That Induces Angiogenesis in Liver Fibrosis. Gastroenterology. 2008;135(5):1729-38.
Research. on June 29, 2021. © 2016 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. Author Manuscript Published OnlineFirst on October 19, 2016; DOI: 10.1158/1078-0432.CCR-16-0460
http://clincancerres.aacrjournals.org/
-
24
82. Kang N, Shah VH, Urrutia R. Membrane-to-Nucleus Signals and Epigenetic Mechanisms for Myofibroblastic Activation and Desmoplastic Stroma: Potential Therapeutic Targets for Liver Metastasis? Molecular Cancer Research. 2015;13(4):604-12.
83. Olaso E, Salado C, Egilegor E, Gutierrez V, Santisteban A, Sancho-Bru P, et al. Proangiogenic role of tumor-activated hepatic stellate cells in experimental melanoma metastasis. Hepatology. 2003;37(3):674-85.
84. Badiola I, Olaso E, Crende O, Friedman SL, Vidal-Vanaclocha F. Discoidin domain receptor 2 deficiency predisposes hepatic tissue to colon carcinoma metastasis. Gut. 2012;61(10):1465-72.
85. Yang X, Lu P, Ishida Y, Kuziel WA, Fujii C, Mukaida N. Attenuated liver tumor formation in the absence of CCR2 with a concomitant reduction in the accumulation of hepatic stellate cells, macrophages and neovascularization. Int J Cancer. 2006;118(2):335-45.
86. Eveno C, Hainaud P, Rampanou A, Bonnin P, Bakhouche S, Dupuy E, et al. Proof of prometastatic niche induction by hepatic stellate cells. J Surg Res. 2015;194(2):496-504.
87. Liu C, Billadeau DD, Abdelhakim H, Leof E, Kaibuchi K, Bernabeu C, et al. IQGAP1 suppresses TbetaRII-mediated myofibroblastic activation and metastatic growth in liver. J Clin Invest. 2013;123(3):1138-56.
88. Terada T, Makimoto K, Terayama N, Suzuki Y, Nakanuma Y. Alpha-smooth muscle actin-positive stromal cells in cholangiocarcinomas, hepatocellular carcinomas and metastatic liver carcinomas. J Hepatol. 1996;24(6):706-12.
89. Ju MJ, Qiu SJ, Fan J, Xiao YS, Gao Q, Zhou J, et al. Peritumoral activated hepatic stellate cells predict poor clinical outcome in hepatocellular carcinoma after curative resection. Am J Clin Pathol. 2009;131(4):498-510.
90. Sirica AE, Gores GJ. Desmoplastic stroma and cholangiocarcinoma: clinical implications and therapeutic targeting. Hepatology. 2014;59(6):2397-402.
91. Brenner DA, Kisseleva T, Scholten D, Paik YH, Iwaisako K, Inokuchi S, et al. Origin of myofibroblasts in liver fibrosis. Fibrogenesis Tissue Repair. 2012;5(Suppl 1):S17.
92. Mueller L, Goumas FA, Affeldt M, Sandtner S, Gehling UM, Brilloff S, et al. Stromal fibroblasts in colorectal liver metastases originate from resident fibroblasts and generate an inflammatory microenvironment. Am J Pathol. 2007;171(5):1608-18.
93. Wang J, Fallavollita L, Brodt P. Inhibition of experimental hepatic metastasis by a monoclonal antibody that blocks tumor-hepatocyte interaction. J Immunother Emphasis Tumor Immunol. 1994;16(4):294-302.
94. Mook ORF, van Marie J, Jonges R, Vreeling-Sindelarova H, Frederiks WM, Van Noorden CJF. Interactions between colon cancer cells and hepatocytes in rats in relation to metastasis. Journal of Cellular and Molecular Medicine. 2008;12(5b):2052-61.
95. Shimizu S, Yamada N, Sawada T, Ikeda K, Nakatani K, Seki S, et al. Ultrastructure of early phase hepatic metastasis of human colon carcinoma cells with special reference to desmosomal junctions with hepatocytes. Pathology International. 2000;50(12):953-9.
Research. on June 29, 2021. © 2016 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. Author Manuscript Published OnlineFirst on October 19, 2016; DOI: 10.1158/1078-0432.CCR-16-0460
http://clincancerres.aacrjournals.org/
-
25
96. Huang J, Pan C, Hu H, Zheng S, Ding L. Osteopontin-Enhanced Hepatic Metastasis of Colorectal Cancer Cells. PLoS ONE. 2012;7(10):e47901.
97. Tabaries S, Dupuy F, Dong Z, Monast A, Annis MG, Spicer J, et al. Claudin-2 promotes breast cancer liver metastasis by facilitating tumor cell interactions with hepatocytes. Mol Cell Biol. 2012;32(15):2979-91.
98. Georges R, Bergmann F, Hamdi H, Zepp M, Eyol E, Hielscher T, et al. Sequential biphasic changes in claudin1 and claudin4 expression are correlated to colorectal cancer progression and liver metastasis. Journal of Cellular and Molecular Medicine. 2012;16(2):260-72.
99. Radinsky R, Risin S, Fan D, Dong Z, Bielenberg D, Bucana CD, et al. Level and function of epidermal growth factor receptor predict the metastatic potential of human colon carcinoma cells. Clin Cancer Res. 1995;1(1):19-31.
100. Zvibel I, Wagner A, Pasmanik-Chor M, Varol C, Oron-Karni V, Santo EM, et al. Transcriptional profiling identifies genes induced by hepatocyte-derived extracellular matrix in metastatic human colorectal cancer cell lines. Clin Exp Metastasis. 2013;30(2):189-200.
101. Li H, Fan X, Stoicov C, Liu JH, Zubair S, Tsai E, et al. Human and mouse colon cancer utilizes CD95 signaling for local growth and metastatic spread to liver. Gastroenterology. 2009;137(3):934-44.e4.
102. Long L, Nip J, Brodt P. Paracrine growth stimulation by hepatocyte-derived insulin-like growth factor-1: a regulatory mechanism for carcinoma cells metastatic to the liver. Cancer Res. 1994;54(14):3732-7.
103. Long L, Rubin R, Baserga R, Brodt P. Loss of the metastatic phenotype in murine carcinoma cells expressing an antisense RNA to the insulin-like growth factor receptor. Cancer Res. 1995;55(5):1006-9.
104. Samani AA, Chevet E, Fallavollita L, Galipeau J, Brodt P. Loss of tumorigenicity and metastatic potential in carcinoma cells expressing the extracellular domain of the type 1 insulin-like growth factor receptor. Cancer Res. 2004;64(10):3380-5.
105. Wang N, Rayes RF, Elahi SM, Lu Y, Hancock MA, Massie B, et al. The IGF-Trap: Novel Inhibitor of Carcinoma Growth and Metastasis. Mol Cancer Ther. 2015;14(4):982-93.
106. Wagh P, Peace BE, Waltz SE. The Met-Related Receptor Tyrosine Kinase Ron in Tumor Growth and Metastasis. Advances in cancer research. 2008;100:1-33.
107. Yoshioka T, Nishikawa Y, Ito R, Kawamata M, Doi Y, Yamamoto Y, et al. Significance of integrin alphavbeta5 and erbB3 in enhanced cell migration and liver metastasis of colon carcinomas stimulated by hepatocyte-derived heregulin. Cancer Sci. 2010;101(9):2011-8.
108. Dome B, Hendrix MJ, Paku S, Tovari J, Timar J. Alternative vascularization mechanisms in cancer: Pathology and therapeutic implications. Am J Pathol. 2007;170(1):1-15.
109. Tabaries S, Annis MG, Hsu BE, Tam CE, Savage P, Park M, et al. Lyn modulates Claudin-2 expression and is a therapeutic target for breast cancer liver metastasis. Oncotarget. 2015;6(11):9476-87.
Research. on June 29, 2021. © 2016 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. Author Manuscript Published OnlineFirst on October 19, 2016; DOI: 10.1158/1078-0432.CCR-16-0460
http://clincancerres.aacrjournals.org/
-
26
110. Hadrup S, Donia M, Thor Straten P. Effector CD4 and CD8 T cells and their role in the tumor microenvironment. Cancer Microenviron. 2013;6(2):123-33.
111. Butt AQ, Mills KH. Immunosuppressive networks and checkpoints controlling antitumor immunity and their blockade in the development of cancer immunotherapeutics and vaccines. Oncogene. 2014;33(38):4623-31.
112. Facciabene A, Motz GT, Coukos G. T-regulatory cells: key players in tumor immune escape and angiogenesis. Cancer Res. 2012;72(9):2162-71.
113. Wolf AM, Wolf D, Steurer M, Gastl G, Gunsilius E, Grubeck-Loebenstein B. Increase of regulatory T cells in the peripheral blood of cancer patients. Clin Cancer Res. 2003;9(2):606-12.
114. Connolly MK, Mallen-St Clair J, Bedrosian AS, Malhotra A, Vera V, Ibrahim J, et al. Distinct populations of metastases-enabling myeloid cells expand in the liver of mice harboring invasive and preinvasive intra-abdominal tumor. Journal of leukocyte biology. 2010;87(4):713-25.
115. Correale P, Rotundo MS, Del Vecchio MT, Remondo C, Migali C, Ginanneschi C, et al. Regulatory (FoxP3+) T-cell tumor infiltration is a favorable prognostic factor in advanced colon cancer patients undergoing chemo or chemoimmunotherapy. J Immunother. 2010;33(4):435-41.
116. Rech AJ, Vonderheide RH. Clinical use of anti-CD25 antibody daclizumab to enhance immune responses to tumor antigen vaccination by targeting regulatory T cells. Ann N Y Acad Sci. 2009;1174:99-106.
117. Rech AJ, Mick R, Martin S, Recio A, Aqui NA, Powell DJ, Jr., et al. CD25 blockade depletes and selectively reprograms regulatory T cells in concert with immunotherapy in cancer patients. Sci Transl Med. 2012;4(134):134ra62.
118. Keskinov AA, Shurin MR. Myeloid regulatory cells in tumor spreading and metastasis. Immunobiology. 2014.
119. Almand B, Clark JI, Nikitina E, van Beynen J, English NR, Knight SC, et al. Increased production of immature myeloid cells in cancer patients: a mechanism of immunosuppression in cancer. J Immunol. 2001;166(1):678-89.
120. Gabrilovich DI, Ostrand-Rosenberg S, Bronte V. Coordinated regulation of myeloid cells by tumours. Nat Rev Immunol. 2012;12(4):253-68.
121. Haverkamp JM, Smith AM, Weinlich R, Dillon CP, Qualls JE, Neale G, et al. Myeloid-derived suppressor activity is mediated by monocytic lineages maintained by continuous inhibition of extrinsic and intrinsic death pathways. Immunity. 2014;41(6):947-59.
122. Khaled YS, Ammori BJ, Elkord E. Increased levels of granulocytic myeloid-derived suppressor cells in peripheral blood and tumour tissue of pancreatic cancer patients. J Immunol Res. 2014;2014:879897.
123. Meyer C, Cagnon L, Costa-Nunes CM, Baumgaertner P, Montandon N, Leyvraz L, et al. Frequencies of circulating MDSC correlate with clinical outcome of melanoma patients treated with ipilimumab. Cancer Immunol Immunother. 2014;63(3):247-57.
Research. on June 29, 2021. © 2016 American Association for Cancerclincancerres.aacrjournals.org Downloaded from
Author manuscripts have been peer reviewed and accepted for publication but have not yet been edited. Author Manuscript Published OnlineFirst on October 19, 2016; DOI: 10.1158/1078-0432.CCR-16-0460
http://clincancerres.aacrjournals.org/
-
27
124. Kusmartsev S, Nefedova Y, Yoder D, Gabrilovich DI. Antigen-specific inhibition of CD8+ T cell response by immature myeloid cells in cancer is mediated by reactive oxygen species. J Immunol. 2004;172(2):989-99.
125. Huang B, Pan PY, Li Q, Sato AI, Levy DE, Bromberg J, et al. Gr-1+CD115+ immature myeloid suppressor cells mediate the development of tumor-induced T regulatory cells and T-cell anergy in tumor-bearing host. Cancer Res. 2006;66(2):1123-31.
126. Diaz-Montero CM, Salem ML, Nishimura MI, Garrett-Mayer E, Cole DJ, Montero AJ. Increased circulating myeloid-derived suppressor cells correlate with clinical cancer stage, metastatic tumor burden, and doxorubicin-cyclophosphamide chemotherapy. Cancer Immunol Immunother. 2009;58(1):49-59.
127. Zhao L, Lim SY, Gordon-Weeks AN, Tapmeier TT, Im JH, Cao Y, et al. Recruitment of a myeloid cell subset (CD11b/Gr1 mid) via CCL2/CCR2 promotes the development of colorectal cancer liver metastasis. Hepatology. 2013;57(2):829-39.
128. Rodriguez PC, Ernstoff MS, Hernandez C, Atkins M, Zabaleta J, Sierra R, et al. Arginase I-producing myeloid-derived suppressor cells in renal cell carcinoma are a subpopulation of activated granulocytes. Cancer Res. 2009;69(4):1553-60.
129. Ugel S, Delpozzo F, Desantis G, Papalini F, Simonato F, Sonda N, et al. Therapeutic targeting of myeloid-derived suppressor cells. Curr Opin Pharmacol. 2009;9(4):470-81.
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Table 1. Cells and mediators involved in the different phases of liver metastasis. Shown are
the four phases of the metastatic process that follow tumor cell invasion into the liver. Listed are the
hepatic cells known to be involved at each phase, the mediators regulating their recruitment and
activation and the factors they produce to block or promote the metastatic process. Note that the
process has been simplified and divided into distinct phases in the interest of clarity. However, it
should be viewed as dynamic with overlapping cellular and molecular drivers at different phases.
Moreover, as the metastatic process advances, the cancer and hepatic cells evolve and their
phenotypes change, as a consequence of their interactions. These newly acquired properties help
propel the process forward (see also Fig 1-3).
Figure legends
Figure 1. The pre-metastatic niche in the liver. Shown is a diagrammatic representation of the
multi-step process involved in the formation of pre-metastatic niches in the liver based on data
described in (11, 12). The symbols used for depiction of different hepatic cells are listed in Figure 3. A
diagrammatic representation of a pancreatic ductal adenocarcinoma (PDAC) is shown in Inset A and
an enlarged image of a Kupffer cell activated by PDAC – derived exosomes is shown in inset B.
Encircled numbers denote cellular and molecular interactions that can potentially be targeted for liver
metastasis prevention, as detailed in the right hand corner box.
Fig 2. The multi-step process of liver colonization by disseminated cancer cells. Shown is a
diagrammatic representation of the major cell types and ECM components in the liver
microenvironment that impact the progression of liver metastasis. The four major phases in the
process are delineated by dashed lines. Depicted in the upper panel are the major inter-cellular
interactions that occur upon entry of the tumor cells into the sinusoidal vessels (the Microvascular
phase) and precede tumor extravasation. Shown in the center two panels are the events following
tumor cell extravasation into the space of Disse divided into the Pre-angiogenic phase (center-left)
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that is orchestrated by stellate cell activation, ECM deposition, cytokine production and the
recruitment of innate and adaptive immune cells and culminates in neovascularization (the vascular
phase)(center-right). These interactions enable tumor expansion (the Growth phase) (bottom panel).
The symbols used for depiction of different hepatic cells are listed in Figure 3 or indicated in the
diagram. The encircled numbers denote potential targets for therapeutic intervention, as detailed in
the boxes inserted within each of the depicted phases.
Fig 3. Parenchymal, non-parenchymal and immune cells of the liver and their role in
metastasis. Listed are the parenchymal and non-parenchymal cells of the liver and their anti and pro-
metastatic functions. Symbols shown for each cell type were used to depict inter-cellular
communications in Figures 1 and 2.
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Phase of the
metastatic process Cell type involved Cell surface markers Soluble factors involved References
Recruiting or activating Produced Pre-metastatic niche Kupffer cell (KC) CD11b, F4/80 M-CSF, GM-CSF, MIF TGF-β, S100P, S100A8 (11-14)
Hepatic stellate cell (HSC) α-SMA, desmin, GFAP KC-derived TGF-β and TNF-α Fibronectin (11, 13)
Myeloid-derived
suppressor cells (MDSC) CD11b, Ly6C, Ly6G Tumor-derived GM-CSF S100A8 (12, 15)
Neutrophils CD11b, Ly6G TIMP-1, SDF-1 S100A8 (7, 14, 68) Post-tumor invasion
(1) Microvascular phase: Tumor cells trapped in the vasculature
Liver sinusoid endothelial
cell (LSEC) CD31, TNFR1, TNFR2, αvβ3, E-
selectin, VCAM-1, ICAM-1 TNF-α, IL-1β, IL-18 ROS, NO, INF, TNF-α (5, 18-20, 23, 31)
Kupffer cell (KC) CD11b, F4/80 M-CSF, GM-CSF, IFNγ TNF-α, IL-1, IL-6, IL-8, IFNγ, MIP-1α, MIP-2, IP-10, MCP-1, CCL5, VEGF
(5, 23, 31, 45-47,
51) Neutrophils CD11b, Ly6G S100A8, S100A9, IL-8, CCL2 TNF-α, ROS, defensins, perforins, elastase (28, 31, 64)
Hepatic natural killer cells
(NK) NK1.1, NK1.2, FcγRIII CXCL9, CXCL10, IL-1, IL-12, IL-15, IL-
18 Grz, Perforin, INFγ, TNF-α (5, 31, 48)
(2) Extravascular, pre-angiogenic: Tumor cells transmigrate into the space of Disse activating a local stromal response
Hepatic stellate cell (HSC) α-SMA, desmin, GFAP KC-derived TGF-β, PDGF, bFGF, SDF-1,IGF-I, CCL2
ECM deposition, MCP-1, CCL5, CCL21,
TGF-β (75-78, 85)
Neutrophils CD11b, Ly6G; N1: ICAM-1; N2: CXCR4
S100A8, S100A9, CXCL1, CXCL2,
CXCL5, TNFα, IL-8, G-CSF, IFNγ, CCL2,
CCL5, TGF-β
TNF-α, ROS, NOS, MMP-8, MMP-9,
elastase, cathepsin G, VEGF (28, 60, 65, 72)
Kupffer cell (KC) CD11b, F4/80 M-CSF, GM-CSF, IFNγ IL-6, VEGF, HGF, MMP-9, MMP-14 (5, 50, 53)
(3) Angiogenic phase: Micrometastases are vascularized
Blood-derived monocytes CD11b, F4/80 TNF-α, MCP-1 VEGF, MMPs, bFGF (57, 60)
Hepatic stellate cell (HSC) α-SMA, desmin, GFAP KC-derived TGF-β, PDGF, bFGF, SDF-1,IGF-I, CCL2
VEGF, angiopoietin-1, MMP-2, -9 and-13 (75, 80-83, 89)
Liver sinusoid endothelial
cell (LSEC) CD31, TNFR1, ICAM-1 VEGF, Ang1, inhibited by Notch1 and
regulated by Ang2 Fibronectin, MIF (23, 41-44)
Macrophages (M2) CD11b, F4/80, Ly6C TGF-β, IL-10 NO, TNFα, IFN, VEGF, EGF, bFGF, TGF-β, IL-10
(57-61)
(4) Growth phase: Metastases expansion
Hepatocytes Albumin, tyrosine aminotransferase
Adhesion to tight junction integral
proteins AREG, EGF, HB-EGF, erB2, IGF-I, HGFL,
ErB3, bFGF (93-99, 102-106,
108)
Tregs CD4, CD25, Foxp3 TGF-β, IL-10, CCL5, CCL22 VEGF, TGF-β, IL-10 (35, 112,125)
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I: 10.1158/1078-0432.CC
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© 2016 American Association for Cancer Research
Figure 1:
A B
ExosomesG-CSF
PDAC
LSEC
BM-derivedmyeloid cells
Vessel lumen
Space of Disse
KC
HSC
Hepatocyte
Fibronectin
S100A8 S100A8
Potential therapeutic strategies:1. Enhancing KC tumoricidal activities2. Inducing HSC apoptosis3. Inhibition of inflammatory mediators
Ly6C+Ly6G+myeloid cells
Neutrophil32
1
aHSC
MIF
?
TGF-
TGF-
TGF-
Tumor-derivedexosomes
Tumor-derivedexosomes
S100A8
Tumor-derived G-CSF
aKC
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© 2016 American Association for Cancer Research
III. Angiogenic phase
Figure 2:
Fas/FasL
Fas/FasL
VEGF
VEGF-R
MMP-9
MMP-9VEGF
LSEC
aKC
I. Microvascular phase
II. Preangiogenic phase
Potential therapeutic strategies3. TGF-bRII blockade4. MDSC depletion5. TNFR2 blockade6. PD-1/PD-L1 blockade
Potential therapeutic strategies10. IGF-I neutralization11. Claudin-2 blockade
IV. Growth phase
Potential therapeutic strategies1. TNF inhibition2. E-selectin blockade
Potential therapeutic strategies7. Blocking M2 polarization8. VEGF inhibition9. N1 induction
sLew×/E-Sel.
TNF-α
TNF-α
TNF-α
TGF-β
TGF-β
TGF-β
IL-10TGF-β
NOTNF-α
TNFR1
HSC
aHSC
aHSC
M1
N1
N2
IGF-I Hepatocyte
M2
CoIIVMDSC
ArgROS
Treg MMPsVEGFTGF-βIGF
CD8+T cell
Tumor cell
Vessel lumen
Space of Disse
Parenchyma
12
3
4
56
7
8
9
11
10
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Figure 3:
Produce ROS, NO, IFN ,TNF-
Express CAM, protect tumorcells from apoptosis, facilitatetransmigration, participate inangiogenesis, induce EMT
Premetastatic niche formationdrive fibrogenic response, ECMproduction, mediate angiogenesis,recruit inflammatory cells,produce MMPs
Mediate tumor adhesion, producegrowth factors (e.g., IGF-1, HGFL),alter tumor transcriptome, undergoEMT to provide stromal support,enhance angiogenesis via bFGF
(5, 11, 12, 47–53)
(59–63)
(114, 118, 124, 125)
Produce perforin, TNF- ,induce Fas/FasL interaction,kill tumor cells
Induce Tregs, block T-cellexpansion, suppress cytotoxicT-cell function, produce ROS,produce arginase
M2 macrophages produceVEGF, EGF, bFGF, induce Tregvia IL-10 and TGF-
M1 macrophages produce NO,TNF- , and T-cell and NKrecruiting chemokines
Participate in premetastaticniche formation, activate LSECCAM, produce VEGF, IL-6,HGF, and MMP-9, activate HSC
Phagocytose tumor cells, causeapoptosis (early in the process),produce TNF- , mobilizeneutrophils and NK
(5, 18–20, 31, 33, 41)
Hepatocytes
Antimetastatic effects ReferencesPrometastatic effectsCell type
Liver sinusoidendothelial cells(LSEC)
Hepatic stellate cells (HSC)
Kupffer cells(KC)
Macrophages
Myeloid-derivedsuppressor cells(MDSC)
Natural killer cells (NK)
T lymphocytes
Neutrophils
(11, 23, 78, 83-87)
Resting Activated
(94–97, 102, 104, 106)
(4)
(28, 64, 78)
(110, 112)Tregs inhibit effector T-cellexpansion, eliminate cytotoxicT cells, subvert immuneactivation, produce VEGF
Cytotoxic T cells kill tumorcells, release perforin andTNF- , recruit macrophages
Participate in premetastaticniche, enhance transendothelialmigration, entrap tumor cells;N2 neutrophils produce VEGF,MMP-9, and CCL5
N1 neutrophils produce ROS,NO, TNF- , defensins, recruitCD8+ T cells
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Published OnlineFirst October 19, 2016.Clin Cancer Res Pnina Brodt pro-metastatic nichesRole of the microenvironment in liver metastasis: from pre- to
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