DETECTION OF A RARE POINT MUTATION AT CODON-59 AND RELATIVELY HIGH-INCIDENCE OF H-RAS MUTATION IN INDIAN ORAL-CANCER

Analysis of H-, K- and N-ras genes for point mutations by PCR-SSCP and direct sequencing of 46 oral SCCs that were previously analyzed for p 53 mutations revealed that 9 (20%) had point mutations in either the H -ras or the N-ras. A novel mutation at codon 59 ((G) under bar CC-->(A ) under bar CC) of H-ras thus far reported only in v-H-ras of Harvey m urine sarcoma virus was observed in a tumor of the cheek. Majority (8/ 9) of these mutations were observed in H-ras, one in N-ras and none in K-ras. This study indicated that the ms gene mutation was relatively high in oral cancers associated with tobacco chewing and the ras and p 53 mutational events seem to be independent and mutually exclusive.