MEN1 gene mutation analysis of sporadic adrenocortical lesions

To clarify the role of the MENI gene in the tumorigenesis of sporadic adren ocortical tumors, we performed a molecular study on 35 adrenocortical lesio ns including 6 hyperplasias, 19 adenomas and In carcinomas. Loss of heteroz ygosity (LOH) of the MENI gene was assessed by PCR using an intragenic (D I I S4946) and 2 flanking microsatellite markers (D I I S4936, PYGM) and/or fluorescence in situ hybridization (FISH) with a 40-kb cosmid probe contain ing the MENI gene. The complete coding sequence of the MENI gene was screen ed for mutations using non-radioactive, FOR-based single-strand conformatio n polymorphism (SSCP) analysis and MDE heteroduplex gel electrophoresis. PC R-LOH and FISH analyses performed in 29 tumors (PCR-LOH in 4, FISH in 17 an d both in 8 tumors) revealed allelic deletion of the MENI locus in 8 (27.5% ) and at 11q13 in 9 (31%) tumors. Furthermore, the frequency of LOH at 11q1 3 was significantly higher in adrenocortical carcinomas (60%) than in benig n lesions (11%). Mutation analysis of tumor samples revealed 9 polymorphism s in 7 tumors (S145S, R1 71Q, R171Q together with L432L) but no mutations, with the exception of one adrenocortical adenoma. The latter tumor containe d a somatic E109X stop codon mutation in exon 2 and a 5178-9G--> A splice m utation in intron 4, which was also detectable in various nontumorous tissu es and blood indicative of a germ-line mutation. The patient, who had no cl inical signs or family history of MENI, later also developed a neuroendocri ne carcinoma (atypical carcinoid) of the lung. Our findings indicate that i nactivating mutations of the MENI tumor-suppressor gene appear not to play a prominent role in the development of sporadic hyperplastic or neoplastic lesions of the adrenal cortex and that the newly reported 5178-9G--> A spli ce mutation in intron 4 might cause a variant of the MEN I phenotype. (C) 1 999 Wiley-Liss, Inc.