Purpose: Cancer-specific p53 mutational spectra have been identified. Data from murine models and human BRCA1-related hereditary breast cancers suggest that both unique and specific BRCA1-associated p53 mutations may be found in BRCA1-related ovarian cancers.
Experimental design: The p53 mutational spectrum from ovarian cancers containing either somatic or germ-line BRCA1 mutations was compared with that of sporadic ovarian cancers defined as those diagnosed with a negative family history for breast/ovarian cancer in a three-generation pedigree. Tumor DNA was screened over exons 2-11 of the p53 gene by the PCR and single-strand confirmation polymorphism analysis of the amplimers. Cycle-based DNA sequencing from separate reactions was used to confirm p53 mutations.
Results: p53 gene mutations were detected in 42 of 86 sporadic ovarian cancers, compared with 13 of 15 cancers with somatic BRCA1 mutations (P = 0.007) and 16 of 20 cancers with germ-line BRCA1 mutations (P = 0.01). p53 null mutations were found in 31.4% of BRCA1 mutant cancers, compared with only 9.3% of the sporadic cancers (P = 0.002). The p53 mutational spectrum of germ-line BRCA1-related cancers was shifted toward transversions, frameshifts, and non-CpG transitions relative to the spectrum of sporadic ovarian cancers. Thirty-three unique ovarian cancer p53 mutations were sequenced. However, the specific p53 mutations in the BRCA1 mutant cancers were no more unique to this cohort than the p53 mutations of the sporadic cancers.
Conclusions: Ovarian cancers containing somatic or germ-line BRCA1 mutations are uniformly accompanied by p53 dysfunction. This finding offers additional support to observations regarding the importance of p53/BRCA1 interactions in ovarian carcinogenesis.