RAS-RELATED TC21 IS ACTIVATED BY MUTATION IN A BREAST-CANCER CELL-LINE, BUT INFREQUENTLY IN BREAST CARCINOMAS IN-VIVO

Activating ras mutations are found in many types of human tumour. Muta tions in Harvey (H-), Kirsten (K-) and neuronal (N-) ras are, however, rarely found in breast carcinomas. TC21 is a ras family member that s hares close homology to H-, K- and N-ras, and activating mutations hav e been found in ovarian carcinoma and leiomyosarcoma cell lines. We ha ve examined panels of cDNAs from breast, ovarian and cervical cell lin es, and primary and metastatic breast tumours for mutations in TC21 us ing a single-strand conformational polymorphism (SSCP)-based assay. On e breast cancer cell line, CAL51, exhibited an altered SSCP pattern, c ompared with normal tissue, which was due to an A-T base change in cod on 72, causing a predicted Gln-Leu activating mutation. Of nine primar y and 15 metastatic breast tumour cDNAs analysed, none exhibited an al tered pattern by SSCP. The apparently wild-type pattern by SSCP analys is was confirmed by sequence analysis of some of the cDNAs assayed. Th us, we conclude that mutations in TC21 are uncommon in breast carcinom as.