42. A Novel Point Mutation of the RET Proto-oncogene in Small Cell Lung Carcinoma Cell Lines

Point mutations of the RET proto-oncogene are associated with the development of inherited diseases including multiple endocrine neoplasia (MEN) type 2, familial medullary thyroid carcinoma (MTC), and Hirschsprung’s disease as well as a part of sporadic MTCs and pheochromocytomas. In the present study, we examined point mutations of the RET proto-oncogene in exons 10, 11 and 16 in small cell lung carcinoma (SCLC) cell lines. A novel point mutation from GCC to GAC at codon 664 in exon 11 was identified in 2 out of 6 SCLC cell lines; this alteration results in an amino acid substitution of aspartic acid for alanine. This point mutation was not detected in other types of cancer cell lines so far examined. Point mutations of the RET proto-oncogene reported previously in exons 10, 11 and 16 in above-mentioned diseases were not detected in the SCLC cell lines. These results suggest that this point mutation of the RET proto-oncogene is closely associated with a part of SCLC.