KI-RAS ONCOGENE MUTATIONS IN HEAD AND NEC K CARCINOMAS

Background: Point mutations of ras genes are one of the most frequent genetic alterations in human malignancies with up to over 95% in certa in tumors. Some studies have presumed a low incidence of point mutatio ns in Ki-ras gene codons 12 and 13 in squamous cell carcinoma of the h ead and neck (SCCHN). The objective of this study was to gain more inf ormation about the significance of point mutations in Ki-ros codons 12 and 13 by investigation of a high number of cases. Methods: By employ ing the polymerase chain reaction with specific primers, 63 fresh tumo r biopsies were investigated by the nonradioisotopic single-strand con formation polymorphism (SSCP) analysis. To cooperate the efficiency an d to characterize the nature of the point mutations, direct fluorescen ce-labeled DNA sequencing was performed in two cases. Results: Five ou t of the 63 (7.9%) SCCHN samples exhibited point mutations in codons 1 2 and 13 by SSCP analysis. In two out of these mutated cases, a G to T transversion in codon 12.2 of the Ki-ras gene was detected. The analy sis of the patient's clinical parameters as well as the histopathologi cal grading and tumor staging revealed no correlation with the Ki-ras point mutation. Conclusions: Ki-ras point mutations in codons 12 and 1 3 are a rare event in SCCHN. These data give additional evidence that these genetic alterations do not play a major role in the development of malignancies of the upper aerodigestive tract.