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BRCA1-induced apoptosis involves inactivation of ERK1/2 activities
Ying Yan1, John P Haas, Min Kim
1Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA.
The Journal of Biological Chemistry
|June 26, 2002
Summary
BRCA1 gene mutations increase cancer risk. This study reveals that BRCA1
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- BRCA1 gene mutations are linked to hereditary breast and ovarian cancers.
- BRCA1 protein is crucial for DNA damage response and genomic stability.
- Previous research suggests BRCA1 overexpression can trigger apoptosis or cell cycle arrest.
Purpose of the Study:
- To investigate the role of mitogen-activated protein kinase (MAPK) family members in cellular responses to BRCA1.
- To compare the effects of wild-type BRCA1 overexpression on MAPK signaling pathways in different cancer cell lines.
Main Methods:
- Utilized recombinant adenovirus (Ad.BRCA1) to overexpress wild-type BRCA1 in MCF-7 (breast) and U2OS (osteosarcoma) cells.
- Monitored the activation of ERK1/2, JNK, and p38 MAPK pathways.
- Employed dominant-negative MEK1 mutants and MEK1/2 inhibitor PD98059 to assess ERK1/2 pathway involvement.
Main Results:
- BRCA1 overexpression induced G(2)/M cell cycle arrest in MCF-7 cells and apoptosis in U2OS cells.
- JNK activation occurred in both cell types, but ERK1/2 activation differed significantly.
- Inhibition of ERK1/2 in MCF-7 cells enhanced BRCA1-induced apoptosis, which involved JNK activation, Fas-L/Fas interaction, and caspase activation.
Conclusions:
- Cellular response to BRCA1 is determined by the interplay of JNK and ERK1/2 signaling pathways.
- BRCA1-induced apoptosis involves JNK activation and the Fas-mediated apoptotic pathway.
- Differential regulation of MAPK pathways contributes to distinct cellular outcomes following BRCA1 expression.