Download 在Ab-1,HCC1428 没有观测到BRCA2 蛋白条带。

二次突变
作为BRCA2突变癌症铂类耐药的一种机制
乳腺中心实验室
许会影
2015.3.15
Background:
About BRCA:
1. Function:
Tumor suppressor gene.
HR
2. BRCA1/2-deficient
Increasing risk of developing cancer in the breast and ovary.
These cancer cells are hypersensitive to platinum but eventually
develop platinum resistance.
3.The mechanism
What is the mechanism of acquired cisplatin resistance of
BRCA2-mutated cancer?
Design of experiment:
12 human breast
cancer cell lines
HCC1428
Sequencing
Function( siRNA)
Canpan-1
14 cisplatin-resistant
Canpan-1 clones
Sequencing
Function(RAD51)
5 recurrent Ovarian cancer
patients with BRCA2 mutation
UW3548
Sequencing
☞ 实验结果:
1
在Ab-1,HCC1428 没有观测到BRCA2 蛋白条带。
Ab-1
full-length
undetectable
HCC1428 Ab-1 undetectable
(BRCA2)
Ab-2 detectabl
Capan-1
推测
HCC1428 BRCA2蛋白缺失
中间片段。
有一个BRC重复序列加上DNA结
合区域以及核定位序列就可以有
效发挥BRCA2的功能。
siRNA 转染
？
顺铂化疗+二次突变 = 顺铂耐药？
Result2:
Result3:
3.
Conclusion:
First, in a cisplatin-resistant BRCA2-mutated breast-cancer cell line, HCC1428, a
secondary genetic change in BRCA2 rescued BRCA2 function.
Second, cisplatin selection of a BRCA2-mutated pancreatic cancer cell line, Capan-1
(refs 3, 4), led to five different secondary mutations that restored the wild-type BRCA2
reading frame. All clones with secondary mutations were resistant both to cisplatin and
to a poly(ADP-ribose) polymerase (PARP) inhibitor (AG14361).
Finally, we evaluated recurrent cancers from patients whose primary BRCA2-mutated
ovarian carcinomas were treated with cisplatin. The recurrent tumour that acquired
cisplatin resistance had undergone reversion of its BRCA2 mutation.
1.secondary mutations that restore the wild-type BRCA2 reading frame may be a
major clinical mediator of acquired resistance to platinum-based chemotherapy.
2.Treatment with cisplatin could facilitate secondary mutations
by increasing the mutation rate via DNA damaging effects.
Outlook
1.A larger clinical study is warranted to determine the prevalence and
clinical significance of in vivo secondary mutations in BRCA2 in human
tumors.
2.Testing for secondary mutations in platinum-treated BRCA2-mutated
cancers may be clinically important, because tumors with secondary
mutations are likely to be resistant to both cisplatin and PARP inhibitors.
3. It will be important to explore mechanisms for restoring drug
sensitivity.