Analysis of K-ras, N-ras, H-ras, and p53 in lung neuroendocrine neoplasms

This study screened 11 samples of typical carcinoid (TC), 4 samples of atyp ical carcinoid (AC), 1 sample of large cell neuroendocrine carcinoma (LCNEC ), and four metastases for point mutations in exons 5 to 8 of the p53 gene, and exons 1 and 2 of the K-ras, H-vas, and N-ras genes using polymerase ch ain reaction (PCR)-single-strand conformation polymorphism (SSCP) and direc t sequencing and by immunohistochemistry for p53. Exon 1 of K-ras was mutat ed in two samples of low-grade AC and a metastasis from one of these tumors (GAT12 and AGT12, respectively). No mutations in N-ras or H-ras were found . Mutations in exons 5 and 8 of the p53 gene were identified in a high-grad e AC and a LCNEC. Positive immunostaining for p53 was present in three samp les, with only one genotypic mutation shown (LCNEC). In conclusion, point m utations of the p53 gene were infrequent in these pulmonary neuroendocrine tumors, did not correlate in all samples with immunostaining, and were asso ciated with the higher-grade tumors. Second, the presence of K-rns mutation s seems to be associated with the higher-grade carcinomas. Third, N-ras and H-ras mutations were not found with these pulmonary neuroendocrine tumors.