hereditary breast cancer in developing countries richard g. pestell, md, phd kimmel cancer center...
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HEREDITARY BREAST CANCER IN DEVELOPING COUNTRIES
Richard G. Pestell, MD, PhD
Kimmel Cancer Center
Jefferson University Hospital
Major Genetic Defects in Breast Cancer
Established Familial Breast Genes (All Tumor Suppressors)
Gene Chromosomal Location
Disease
TP53 (p53)
17p13 (mutated, LOH) Li-Fraumeni syndrome of multiple hereditary cancers
PTEN 10q23 (mutated, LOH) Cowden’s syndrome of multiple hereditary cancers
BRCA-1 17q21 (mutated, LOH) Familial female breast and ovarian cancers
BRCA-2 13q14 (mutated, LOH) Familial female and male breast cancers
Established Breast Cancer Progression Genes
Gene
Chromosomal Location Class Function
C-ERBB2 17q12 Oncogene (amplified) Growth factor receptor subunit
C-MYC 8q24 Oncogene (amplified) Cell-cycle/cell death regulator; protein synthesis
CCND1 (cyclin D1) 11q13 Oncogene (amplified) Cell-cycle G1 regulator
CDKN2 (p16) 9p21 Suppressor gene (methylated, LOH)
Cell-cycle G1 regulator
RB-1 13q14 Suppressor gene (mutated, LOH)
Cell-cycle G1 and G1/S regulator
TP53 (p53) 17p13 Suppressor gene (mutated, LOH)
Cell-cycle/cell death/DNA repair regulator
CDH1 (E-cadherin) 16q22-23 Suppressor gene (methylated, LOH)
Cell-cell adhesion protein
Major Genetic Defects in Breast Cancer
Sex Hormone Regulation of Growth Factor Systems in Breast Cancer
EGF FAMILY
Growth factors: EGF, TGF-, amphiregulin
Receptors: EGFR, c-erbB2
IGF FAMILY
Growth factors: IGF-2
Receptors: IGF-1R, IGF-2R, insulin receptor
Binding proteins: BP-2, BP-3, BP-4, BP-5
TGF- FAMILY
Growth factors: TGF-1, TGF-2, TGF-3
PDGF FAMILY
Growth factors: PDGF-1, PDGF-2
BP, binding protein; EGF (R) , epidermal growth factor (receptor); IGF, insulin-like growth factor; PDGF, platelet-derived growth factor; TGF, transforming growth factor.
Metastatic Cancer
Further phenotypic alterations in cell cycle
Further phenotypic alterations in cell death and response to therapy
Phenotypic changes in growth factor secretion governing angiogenesis and metastatic spread
Mutations in pathways governing invasion CDH1
Defects in mismatch repair of DNA
Predisposing genetic risk
Mutations affecting DNA repair and apoptosis in BRCA-1 BRCA-2
TP53
PTEN
Carcinoma in Situ
Mutations in Growth Factor and Sex Steroid pathways governing the cell cycleC-ERBB2C-MYCCCDN1CDKN2RB-1
Mutations in Cell Death PathwaysTP53
Overall Chromosomal Instability
Hyperplasia
Overstimulation of cell cycle and suppression of apoptosis by Estrogen Progesterone Growth Factors
Immortalization of cells by expression of Telomerase
Genetic Alteration of Mammary Epithelial Cells - Progression of Breast Cancer
BRCA1 Protein Function
• Regulation of cell cycle progression
• DNA repair: “caretaker” function
• Programmed cell death (apoptosis)
• Regulation of gene transcription
BRCA1 Protein: Structural Features
-1863 aa-220 kDa nuclear phosphoprotein-N-terminal RING domain (aa 20-64)
interacts with BARD1ubiquitin ligase activity
-C-terminal TAD (last 95-100 aa)mediates transactivationBRCT repeats
Role in DNA Damage Response
Specialized DNA repair processes-Homology-directed repair-Transcription coupled repair-Mismatch repair-Nucleotide excision repair-Fanconi repair
DNA damage signaling: ATM, ATR, Chk2
DNA damage responsive cell cycle checkpoints: S & G2/M
Regulation of BRCA1 Expression
Increased Expression-cancer chemoprevention – indole-3-carbinol, genistein-mammary epithelial cell differentiation-cell cycle - in late G1, early S-phase
Decreased Expression-30-40% sporadic breast cancers: promoter methylation-ethanol-polycyclic aromatic hydrocarbons – B(a)P, BPDE-persistent organochlorines (PCBs)-p53 activation-Id4 (bHLH transcriptional regulator)
BRCA1 Regulated Transcriptional Pathways
-interacts w/ basal transcription factor (RNA helicase A)-C-terminus: chromatin unfolding activity (COBRA1)-associates w/ Brg1 (SWI/SNF chromatin remodelling)-stimulates Gadd45, p21WAF1, p27Kip1 expression-coactivator for p53-inhibits c-Myc activity and TERT expression-interacts with STAT1–interferon -mediated transcription-regulates nuclear receptor function
BRCA1 transcriptional regulation
BRCA1-interacting proteins
BRCA1-transcription repression
Science, V284, p1354, 1999
BRCA1 represses ER
BRCA1 Domains for ERInhibition
Du-145T47D
220
200
120
100
80
60
40
20
0
Lu
cife
rase
Act
ivit
y(%
of
pcD
NA
3 V
ecto
r C
ontr
ol)
pcD
NA
3
wt
BR
CA
1
5677
-In
sA
Bam
H1
Kp
n 1
Eco
R 1
185d
elA
G
T30
0G
RX
RX
H
5382
InsC
C53
65G
1
1
1
1
1
1
1
1
1
RING NLS Rad51 TAD
1 500 1000 1500 1863
1852
1313
771
302
38
61 Cys/Gly
358 RXRXH
1863
1863
1755
1749Pro/Arg 1863
wt BRCA1
5677-InsA
Bam H1
Kpn 1
EcoR 1
185delAG
T300G
RXRXH
5382InsC
C5365G
LXCXE
ER Binds Cyclin D1
Western IP WB
E2- + - +
A B
ER
ER
HE74
F
1-530
E/F
1-282
DBD LBD
AF-1 AF-2
1-378
ER
HE74
F
1-530
E/F
1-282
1-378
***
Cancer Res, Wang et al 2005
GST-Cyclin D1 Binds to ER
GS
T
GS
T D
1
ER
ER
HE74
F
1-530
E/F
1-282
DBD LBD
AF-1 AF-2
HE19C
***1 595
1 595
179 595
1 554
1 530
1 388
1 282
Cancer Res, Wang et al 2005
Cyclin D1 Overcomes Repression by BRCA1
N C
BRCA1
BRCA1
BRCA1
N CN C
ER ER ER
Co-activator
Co-activator
Co-activator
D1
D1
Hereditary Breast Cancer in Developing Countries
-Relative contribution to breast cancer ?-Common or distinct mutations ?-Role of polymorphisms in onset,progression and therapy(cyclin D1,Bcl2, other) ?-Role in screening- cultural sensitivity vs treatment triage-Economic priorities ?-Global collaboration in molecular epidemiology ?
BRCA1 Inhibits Estrogen-Induced GenesD
ME
M+
10%
FC
S
- + - + E2 (10-6M)- - + + wtBRCA1
pS2
Cathepsin-D
-Actin
DM
EM
+10
%F
CS
- + - + E2 (10-6M)- - + + wtBRCA1
pS2
Cathepsin-D
-Actin
Serum-Free DMEM Serum-Free DMEM