HEREDITARY BREAST CANCER IN DEVELOPING COUNTRIES

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HEREDITARY BREAST CANCER IN DEVELOPING COUNTRIES

• Richard G. Pestell, MD, PhD
• Kimmel Cancer Center
• Jefferson University Hospital

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Major Genetic Defects in Breast Cancer
Established Familial Breast Genes (All Tumor Suppressors) Established Familial Breast Genes (All Tumor Suppressors) 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) Cowdens 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
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Major Genetic Defects in Breast Cancer
Established Breast Cancer Progression Genes Established Breast Cancer Progression Genes Established Breast Cancer Progression Genes 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

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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.
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Genetic Alteration of Mammary Epithelial Cells -
Progression of Breast Cancer
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BRCA1 Protein Function

• Regulation of cell cycle progression
• DNA repair caretaker function
• Programmed cell death (apoptosis)
• Regulation of gene transcription

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BRCA1 Protein Structural Features
-1863 aa -220 kDa nuclear phosphoprotein -N-termin
al RING domain (aa 20-64) interacts with
BARD1 ubiquitin ligase activity -C-terminal TAD
(last 95-100 aa) mediates transactivation BRCT
repeats
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Role in DNA Damage Response
Specialized DNA repair processes -Homology-directe
d 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
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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)
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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 STAT1interferon
??-mediated transcription -regulates nuclear
receptor function
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BRCA1 transcriptional regulation
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BRCA1-interacting proteins
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BRCA1-transcription repression
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BRCA1 represses ERa
Science, V284, p1354, 1999
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BRCA1 Domains for ER??Inhibition
LXCXE
RING NLS Rad51
TAD
220
Du-145 T47D
wt BRCA1
1 500 1000 1500
1863
200
5677-InsA
1
1852
120
?Bam H1
1
1313
Luciferase Activity ( of pcDNA3 Vector Control)
100
?Kpn 1
1
771
80
?EcoR 1
1
302
60
185delAG
1
38
40
T300G
61 Cys/Gly
1
1863
20
RXRXH
1
1863
0
358 RXRXH
5382InsC
RXRXH
T300G
1
1755
?Kpn 1
C5365G
pcDNA3
?EcoR 1
5382InsC
?Bam H1
185delAG
5677-InsA
wt BRCA1
C5365G
1
1749Pro/Arg 1863
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ER? Binds Cyclin D1
A
B
DBD LBD
Western
IP WB
ER?


-
-
AF-1 AF-2
E2






ER?
ER?

HE74
HE74
?F
?F
1-530
1-530
?E/F
?E/F
1-378
1-378
1-282
1-282
Cancer Res, Wang et al 2005
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GST-Cyclin D1 Binds to ER?
DBD LBD
ER?
GST D1
GST
AF-1 AF-2
ER?
1
595

HE74
1
595
HE19C
179
595
?F
1
554
1-530
1
530
?E/F
1
388
1-282
1
282
Cancer Res, Wang et al 2005
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Cyclin D1 Overcomes Repression by BRCA1
BRCA1
D1
Co-activator
D1
Co-activator
BRCA1
N
N
C
C
C
N
ER?
ER?
ER?
Co-activator
BRCA1
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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
?
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BRCA1 Inhibits Estrogen-Induced Genes
Serum-Free DMEM
DMEM10FCS
Serum-Free DMEM
DMEM10FCS
- - E2
(10-6M) - -
wtBRCA1
- - E2
(10-6M) - -
wtBRCA1
pS2
pS2
Cathepsin-D
Cathepsin-D
?-Actin
?-Actin