Germ line and somatic mutations of BRAF V599E in ovarian carcinoma.

It has been shown that ovarian low-grade serous carcinoma evolves out of a stepwise progression from benign serous cystadenoma to serous borderline tumor (SBT) to micropapillary serous carcinoma (MPSC), and that BRAF activation is a very early somatic event in the tumorigenesis. We postulated that BRAF could be a SBT susceptibility gene, and investigated both germ line and somatic mutations of BRAF V599E in 104 ovarian cancer patients. BRAF V599E mutation in histologic samples was found in 5 (24%) of 21 SBTs, 1 (33%) of 3 MPSCs, 1 (17%) of 6 endometrioid carcinomas, but not detected in 42 conventional serous carcinomas, 12 mucinous borderline tumors, 10 mucinous, and 10 clear-cell carcinomas. No V599E mutation could be detected in blood samples from these 104 patients. We also found no BRAF V599E mutation in 101 normal healthy women and 10 well-established ovarian cancer cell lines. Our results suggest that BRAF gene plays a "gatekeeper" role but does not act as a predisposition gene in the development of low-grade serous carcinomas.