MUTATIONAL ANALYSIS OF THE BRCA1 TUMOR-SUPPRESSOR GENE IN ENDOMETRIALCARCINOMA

Objective. To investigate whether alteration of BRCA1 tumor suppressor gene occurs in sporadic endometrial carcinomas. Methods. Genomic DNAs were prepared from 33 consecutively collected endometrial carcinoma t issues for BRCA1 mutational analysis. To screen for BRCA1 mutation, po lymerase chain reaction (PCR) amplification and single strand conforma tion polymorphism (SSCP) technique were used with 41 overlapping PCR p rimer pairs for the 23 coding exons of BRCA1. Tumors that demonstrated SSCP variants were further subjected to direct DNA sequencing in the appropriate exons to identify the DNA alteration. Results. In addition to detecting a previously described polymorphism in exon II, single s trand conformation polymorphism analysis of the 33 endometrial cancers identified 3 tumors with mobility shifts. Two tumors shifted in exon 3 and showed the same pattern of band shift. The other tumor shifted i n exon 9. DNA sequencing revealed sequence alterations in the 3 tumors ; all appeared heterozygous. In the 2 tumors shifted in exon 3, the se quence alteration caused no amino acid change and was consistent with an infrequent silent polymorphism. In the third tumor, a missense alte ration at codon 191 was detected and was recognized as germline in ori gin. Conclusions. Because a normal allele of BRCA1 was retained in the tumor where a germline missense alteration was detected, the heterozy gous DNA alteration should not be cancer predisposing in terms of the two-hit model for inactivation of the tumor suppressor gene. We conclu de that mutation of BRCA1 may not be involved in the development of sp oradic endometrial cancer. (C) 1997 Academic Press.