Assessment of TP53 mutation using purified tissue samples of ovarian serous carcinomas reveals a higher mutation rate than previously reported and does not correlate with drug resistance

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The TP53 mutation frequency in ovarian serous carcinomas has been reported to range between 50% and 80%, but a stringent analysis of TP53 using purified epithelial samples has not yet been performed to accurately assess the mutation frequency and to correlate it with the histologic grade. The purpose of this study was to assess the TP53 mutational profile in a relatively large series of high-grade (53 primary and 18 recurrent) and 13 low-grade ovarian serous tumors using DNA isolated from affinity-purified tumor cells and to correlate it with in vitro drug resistance. All samples were affinity purified, and the tumor DNA was analyzed for TP53 mutations in exons 4-9. In vitro drug resistance assays to carboplatin, cisplatin, paclitaxel, and taxotere were performed on the same tumor samples and correlated with the TP53 mutation status. TP53 mutations were detected in 57 (80.3%) of 71 high-grade carcinomas and in one (7.8%) of 13 low-grade serous tumors (an invasive low-grade serous carcinoma). The mutations were predominantly missense mutations (59.6%). TP53 mutations were associated with high-grade serous carcinomas and recurrent disease (P < 0.0001). There was no statistically significant correlation between TP53 mutation status and drug resistance assays or clinical stage (P > 0.25). The frequency of TP53 mutations using purified tumor DNA from ovarian serous carcinomas was 80.3%, which is much higher than previously reported. Furthermore, we found that TP53 is not directly involved in the development of drug resistance in high-grade ovarian serous carcinomas.