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Common nonsense mutations in RAD52
D W Bell1, D C Wahrer, D H Kang
1Center for Cancer Risk Analysis, Massachusetts General Hospital Cancer Center, and Harvard Medical School, Charlestown 02129, USA.
Abstract:
RAD51, RAD52, and RAD54 encode proteins that are critical to the repair of double-strand DNA breaks by homologous recombination. The physical interactions among the products of RAD51, BRCA1, and BRCA2 have suggested that the BRCA1 and BRCA2 breast cancer susceptibility genes may function, at least in part, in this DNA damage repair pathway. Given the observation that different genes within a common functional pathway may be targeted by mutations in human cancers, we analyzed RAD51, RAD52, and RAD54 for the presence of germ-line mutations in 100 cases with early-onset breast cancer and for somatic mutations in 15 human breast cancer cell lines. Two premature stop codons, Ser346ter and Tyr415ter, were identified in germ-line RAD52 alleles from 5% of early-onset breast cancer cases. Together, these two heterozygous mutations were also found in 8% of a healthy control population, indicating that they do not confer an increased risk for breast cancer. A rare germ-line missense mutation was identified in RAD54, whereas no sequence variants were found in RAD51. None of the three RAD genes demonstrated somatic mutations in breast cancer cell lines. We conclude that, despite their potential functional association with the BRCA gene products, RAD51, RAD52, and RAD54 are not themselves targeted by mutations in human breast cancer. The presence of common nonsense mutations in RAD52 within the population may have significance for other conditions associated with potential alterations in DNA damage repair pathways.
Insights
Researchers investigated RAD51, RAD52, and RAD54 genes for mutations in breast cancer. They found no evidence that these DNA repair genes are mutated in human breast cancer, suggesting they are not a primary target in this disease.
Area of Science:
- Genetics
- Molecular Biology
- Cancer Research
Background:
- Homologous recombination is crucial for repairing double-strand DNA breaks.
- RAD51, RAD52, and RAD54 proteins are key players in this DNA repair pathway.
- BRCA1 and BRCA2 breast cancer susceptibility genes interact with RAD proteins, suggesting a functional link.
Purpose of the Study:
- To investigate RAD51, RAD52, and RAD54 genes for germ-line and somatic mutations in breast cancer.
- To determine if these DNA repair genes are mutated in early-onset breast cancer and cell lines.
- To assess the potential role of RAD gene mutations in breast cancer development.
Main Methods:
- Screening of RAD51, RAD52, and RAD54 genes for germ-line mutations in 100 early-onset breast cancer cases.
- Analysis of RAD genes for somatic mutations in 15 human breast cancer cell lines.
- Comparison of mutation frequencies with a healthy control population.
Main Results:
- Two heterozygous premature stop codon mutations (Ser346ter, Tyr415ter) were found in RAD52 germ-line alleles in 5% of breast cancer cases and 8% of controls.
- A rare germ-line missense mutation was identified in RAD54; no variants were found in RAD51.
- No somatic mutations in RAD51, RAD52, or RAD54 were detected in breast cancer cell lines.
Conclusions:
- RAD51, RAD52, and RAD54 are not significantly mutated in human breast cancer, despite their role in DNA repair and association with BRCA genes.
- The identified RAD52 mutations are common in the general population and do not increase breast cancer risk.
- These findings suggest that RAD51, RAD52, and RAD54 are unlikely to be primary targets for mutations in breast cancer.