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Silencing of BRCA2 to Identify Novel BRCA2-regulated Biological Functions in Cultured Human Cells
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Degradation of BRCA2 in alkyltransferase-mediated DNA repair and its clinical implications

Subha Philip1, Srividya Swaminathan, Sergey G Kuznetsov

  • 1Mouse Cancer Genetics Program, Center for Cancer Research, and Pathology Histotechnology Laboratory, Science Applications International Corporation-Frederick, Inc., National Cancer Institute at Frederick, Frederick, Maryland 21702, USA.

Cancer Research
|December 3, 2008
PubMed

Insights

BRCA2 protein aids in DNA repair by interacting with AGT. Inhibiting AGT with O6-benzylguanine degrades BRCA2, making cancer cells more sensitive to chemotherapy.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • DNA Repair Mechanisms

Background:

  • Germ-line mutations in BRCA2 are associated with familial breast cancer.
  • BRCA2 is crucial for repairing DNA double-strand breaks.
  • The DNA repair protein O6-alkylguanine DNA alkyltransferase (AGT) repairs O6-methylguanine adducts.

Purpose of the Study:

  • To investigate the role of BRCA2 in AGT-mediated DNA repair.
  • To explore the interaction between BRCA2 and AGT.
  • To assess the therapeutic potential of targeting this interaction.

Main Methods:

  • Studied the physical association and degradation of BRCA2 and AGT.
  • Utilized BRCA2 mutants with a 29-amino-acid deletion.
  • Assessed sensitivity of mouse embryonic fibroblasts to alkylating agents.
  • Investigated the effect of O6-benzylguanine (O6BG) on BRCA2 degradation and cell sensitivity to cisplatin.

Main Results:

  • BRCA2 physically associates with AGT and undergoes degradation during repair.
  • A specific BRCA2 deletion mutant failed to bind AGT, leading to no degradation and increased sensitivity to alkylating agents.
  • O6BG, an AGT inhibitor, induced BRCA2 degradation.
  • O6BG pretreatment significantly increased cancer cell sensitivity to cisplatin and other chemotherapeutic agents across various human tumor cell lines.

Conclusions:

  • BRCA2 is involved in AGT-mediated repair of O6-methylguanine DNA adducts.
  • Targeted degradation of BRCA2, induced by AGT inhibition, enhances cancer cell sensitivity to DNA-damaging chemotherapeutic agents.
  • Targeting BRCA2 degradation represents a promising strategy for cancer therapy and chemosensitization.

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