Loss of heterozygosity in gastric neuroendocrine tumor

The MEN1 gene locus is known to be partly responsible for the tumorigenesis of sporadic gastric neuro-endocrine tumors, but the genetic events that dr ive the neoplastic process of this tumor remain largely unknown. In order t o sa een the tumor suppressor genes associated with the tumorigenesis of ga stric neuroendocrine tumors, 15 neuroendocrine carcinomas and three carcino id tumors in the stomach were analyzed for loss of heterozygosity (LOH) usi ng 22 microsatellite markers. In our study, the gastric neuroendocrine tumo rs showed a high rate of LOH in chromosomes 8p (82%), 15q (58%), 17p (57%), lip (50%), 12p (50%) and 13q (50%). The mean fractional allelic loss (FAL) was higher in the neuroendocrine carcinoma components than in the adenocar cinoma components (0.42 versus 0.33, respectively). In foul cases, the aden ocarcinoma components showed discordant LOH patterns from those of the neur oendocrine counterparts in half of the informative chromosomes analyzed. Co mparably, the gastric neuroendocrine carcinomas exhibited a higher LOH freq uency on 8p and a lower LOH on 7q than did the gastric adenocarcinomas. It is suggested that chromosome 8p is the possible location of the tumor suppr essor genes associated with the tumorigenesis of gastric neuroendocrine tum ors.