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Cancer cell Migration during Invasion and
Metastasis
By Lokesh Patil
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Overview of cancer spreading stages
Primary tumor formation Local Invasion Intravasation
Transport and survival in through
circulation
Arrest at distant organ siteExtravasation
Micrometastasis formation
Metastatic colonization
Clinically detectable metastases
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Invasion-Metastasis cascade
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Tumor formation
• Because of failure in DNA replication of cells causing uncontrolled division
• Occurs at molecular level in the cell nucleus
• Cellullar instability->daughter cells interacting with environment
• At cellular level->dynamics have longer space scale and slower time scale that molecular level.
e.g, enzymatic degradation in ms whereas cell replication about a day Fig 1 : Comparison of normal and
Cancer cell division
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Local InvasionMMP(Matrix
Metalloproteinase) driven proteolysis causes loss of
BM barrier
Invasion of cancer cells into stromal compartment
Stroma becomes increasingly reactive
These Stromal cells enhance the aggressiveness
of cancer cells
Fig 2: Local Invasion(marked in circle)
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Intravasation• Entry of cancer cells into the lumina of blood vessel
or lymphatic vessel • Hematogenous circulation is the major mechanism for cancer cell dispersion• Facilitated by molecular changes • Strongly influenced by structural characteristics of tumor-associated blood vessels• Weak blood vessel-endothelial cells interactions promote intravasation Fig 3 : Tumor cell crossing the endothelial
cell barrier
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CTC(Circulating tumor cells) survival
• CTCs are anchorage dependent cells• CTCs(20-30um)• Luminal Dia. of capillaries(~8um)• Therefore CTCs spend short amount of time through circulation hence avoiding anoikis• CTCs also need to avoid hemodymic shear forces and predation by immune cells. They form emboli with platelets to avoid this.• Important clinical relevance
Fig 4: CTC pathway
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CTC arrest and Extravasation
• Still unknown whether specificity for sites is caused by vessel size restrictions or predetermined predilections
Tumor Metastasis: Molecular Insights and Evolving Paradigms Valastyan, Scott; Weinberg, Robert�A. Cell
doi:10.1016/j.cell.2011.09.024 (volume 147 issue 2 pp.275 - 292)
Fig 5: Metastasis tropism: Carcinomas originating from a particular epithelial tissue form detectablemetastases in only a limited subset of theoretically possible distant organ sites. Shown here are the most common sites of metastasis for six well-studied carcinoma types. Primary tumors are depicted in red. Thickness of black linesreflects the relative frequencies with which a given primary tumor type metastasizes to the indicated distant organ site.
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CTC arrest and ExtravasationSteps of Extravasation: 1) Transient Adhesion of TC(tumor cell) to EC(Endothelial cell)-involves endothelial adhesion molecules E and P selectins. This step is associated with rolling
2) This step causes even more firm adhesion
3) The TC slips through endothelial cell-cell junction
Fig 6: Simplistic mechanism of Extravasation
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In-vitro Extravasation model- Factors affecting TC transmigration
-48 well “flow migration” Boyden chamber used
Variables that are quantified:-PMN tethering freq is determined(which is normalized against cell flux on surface)-Total no. of tethered PMNs(polymorphonuclear neutrophils)-No. of collisions b/w TCs and tethered PMNs-Aggregation of TCs with tethered PMNs as a result of collisions-Final attachment of aggregates with EC
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Effect of PMN, ICAM-1 and E-selectin on cell migration
Fig 7 : All cases are at flow shear stress of 0.4 dyn/cm2 C8161, WM9, WM35 are type of cancer cells from cell lines ICAM 1- Intercellular adhesion molecule (a) Effect of addition of PMN to TC cell supension (b) Effect of blocking I-CAM1 and E-selectinDong, C., 2011. Adhesion and Signaling of Tumor Cells to Leukocytes and Endothelium in Cancer Metastasis Studies in Mechanobiology, Tissue Engineering and Biomaterials 4: 477-521
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Effect of fluid shear on tumor cell(TC) migration
• Either shear rate(ý) or shear stress (τ=μý) was kept constant, while other one varied by changing μ.
Dong, C., 2011. Adhesion and Signaling of Tumor Cells to Leukocytes and Endothelium in Cancer Metastasis Studies in Mechanobiology, Tissue Engineering and Biomaterials 4: 477-521
Fig 8 : (a)TC migration varies under constant shear stress but increasing shear rate [(b), (c)]migration does not change for changes in shear stress data
Conclusion:-PMN facilitated migration is affected by shear rate and not by shear stress
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Receptor-ligand mechanics
-kon governs the likelyhood of receptor to form bond with ligand on other cell
AL - available surface area for receptor on ligand bearing cellnL - no. of ligands of cellnB - no. of bonds already formedЄ – distance b/w two cellsk⁰on – Association rate for receptor-ligand binding under zero- force conditionσts – bond spring constantλ - equilibrium length
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Mathematical model for tissue invasion
Hybrid discrete-continuum model for tissue invasion
Assumptions-Invasion triggered by peripheral cancer cell-ECM
contact- Amount of molecules interacting is large enough - Cells are considered discrete particles About the model• Two scale approach-Intracellular environment
affects the extracellular environment• Continuum part of model describes chemical-ECM
interactions• The discrete part models the individual cells
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Chemical-ECM environmentCancer cells in contact
with the protein network release MMPs
ECM is modified by degradation[Fig 9 ]
Change in adjacent stroma configuration
Protein network-cell interaction causing mitosis
via GF absorbtion in degraded ECM
Stimulates cells to migrate via chemotaxis and haptotaxis
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Chemical-ECM environmentEquations governing enzymes’ interactions with
adjacent stroma
2- Diffusion of enzymes in surrounding environment
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E(x,t) – Conc. Of MMPs/uPAs(Urokinase plasminogen actovator)
M(x,t)- Density of ECM
A(x,t) – Density of degraded ECM, in which cells can absorb GFsBє(x) - ball of radius є , centered at xi
1 - Instantaneous local enzyme production
Where N(x, t) is the no. of cellsat time t in surrounding neighbourhoodsuch that
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Chemical-ECM environment
Fig 9 : Change in ECM density as it is degraded by a single cell placed on a petri dish
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Chemical-ECM environment
Fig 10 : Plot of concentration profile overtime of chemoattractants and GFs as they are released from the ECM
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Cell modelling
Cells are assumed as free interacting particles in 2d space
• Two cells interact with each other according to a potential energy function(represents cell-cell adhesion)
• Potential energy of cell-cell bond at time t is given as
• h->capacity to bond
Ignacio Ramis-Conde, Mark A.J. Chaplain, Alexander R.A. Anderson, Mathematical modelling of cancer cell invasion of tissue, Mathematical and Computer Modelling, Volume 47, Issues 5-6, March 2008, Pages 533-545, ISSN 0895-7177, 10.1016/j.mcm.2007.02.034.
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Intercellular Adhesion as a Potential function
Fig 11 : (Left)Interaction energy between two cells separated by a distance x(scaled relative to radius of avg cancer cell. (Right) Interaction energy between two cells in a 2D domain
Ignacio Ramis-Conde, Mark A.J. Chaplain, Alexander R.A. Anderson, Mathematical modelling of cancer cell invasion of tissue, Mathematical and Computer Modelling, Volume 47, Issues 5-6, March 2008, Pages 533-545, ISSN 0895-7177, 10.1016/j.mcm.2007.02.034.
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Modelling cell movement
-Cells movement is governed by potential function
-In absence of any interaction with ECM motion is decided solely by
- Cells are assumed to move at constant speed
- In case of cell-ECM interactions, cell movement is also affected by chemoattractant gradients
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Cell mitosis
• Two causes-Autocrine stimulus and cell-GF interaction
R(xi , t) – Probability function for mitosis rateP0 – Mitosis rate caused solely by autocrine stimulus
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Tumor growth
Fig 12:Evolution of cancer cells as they invade the ECM
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Metastasis Studies in Mechanobiology, Tissue Engineering and Biomaterials 4: 477-521[6] Ignacio Ramis-Conde, Mark A.J. Chaplain, Alexander R.A. Anderson, Mathematical modelling of cancer cell
invasion of tissue, Mathematical and Computer Modelling, Volume 47, Issues 5-6, March 2008, Pages 533-545, ISSN 0895-7177, 10.1016/j.mcm.2007.02.034.
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