Allelic gains and losses in distinct regions of chromosome 6 in gastric carcinoma

In gastric cancer, alterations in the long arm of chromosome 6 are a freque nt event. Two regions of heterozygous loss have been described: 6q16.3 simi lar to 6q23 and 6q26 similar to 6q27. We have evaluated by microsatellite a nd FISH analyses the 6q status of three cell lines that we established from primary gastric carcinomas xenografted in nude mice, in order to elucidate the underlying mechanisms of 6q alterations. Alterations of the long arm o f chromosome 6 were found in all three xenografts and corresponding cell li nes. Allelic imbalance (AI) was found in the three cases, by microsatellite analysis. Fluorescence in situ hybridization analyses clearly demonstrated a duplication of the larger part of the 6q arm in all three cell lines. Tw o of the cell lines and the corresponding xenografts showed, in addition, c omplete loss of one of the parental alleles at the terminal part of 6q. Thu s, the AI observed along the long arm of chromosome 6 is represented by gai n of alleles in one distinct chromosomal segment and loss of alleles in ano ther distinct segment. (C) 2001 Elsevier Science Inc. All rights reserved.