구강암 세포주의 c-Ki-ras 2 유전자 발현 및 점돌연변이에 관한 연구

c-Ki-ras 2 gene expression and point mutation in human oral cancer

Five oral cancer cell lines, FaDu, HEp-2 SCC-4, 1483, OEC-M1, and one epidermoid carcinoma cell line, A-431, were examined for their expression level of c-Ki-ras 2 gene and the presence of activating mutations. Northern blot analysis revealed that the expression level of c-Ki-ras 2 mRNA of FaDu cells was 4 times that of primary cultured normal human oral keratinocytes (NHOK). OEC-M1 cells expressed mRNA of a little smaller size than normal and the expression level was much higher than in NHOK. Other cells expressed c-Ki-ras 2 mRNA at comparable levels to NHOK. DNA sequencing of c-Ki-ras 2 gene exon 1 and exon 2 was performed using polymerase chain reactionamplified DNA fragments. OEC-M1 cells had three point mutations in their c-Ki-ras 2 gene exon 1 and exon 2 resulting in amino acid substitutions, asparagine to aspartic acid, phenylalanine to leucine, and glycine to arginine at 24the, 28th and 53rd residues respectively. However, other cells had no mutation in their c-Ki-ras 2 gene exon 1 and exon 2. This result shows that abberant expression of c-ki-ras 2 gene and the point mutations are quite often associated with oral cancer.