EXPRESSION OF HIGH-MOBILITY GROUP-1 MESSENGER-RNA IN HUMAN GASTROINTESTINAL ADENOCARCINOMA AND CORRESPONDING NONCANCEROUS MUCOSA

An 1194-nucleotide complementary DNA clone, FMI, encoding a human high -mobility group-1 protein (HMG-I) was isolated from a well-differentia ted human gastric-carcinoma cell line complementary DNA library by a d ifferential screening method. FMI is similar to the published human HM G-1 in mature protein, with only 3 different codons at positions 11, 1 49, and 190. We analyzed 33 gastric and colorectal adenocarcinomas for expression of the FMI gene, Northern-blot analysis revealed that all of the cancers expressed FMI at a higher level than in corresponding n on-cancerous mucosa, with 2 transcripts of approximately 1.4 and 2.4 k ilobases. The FMI expression level in the non-cancerous tissues increa sed with the depth of accompanying cancer invasion. Only 18.2% of well -differentiated cancers showed a higher expression level in correspond ing non-cancerous tissues, whereas the expression in corresponding non -cancerous tissues was significantly higher in moderately (60%) and po orly differentiated (83.3%) cancers. In situ hybridization demonstrate d the location of FMI mRNA in well- and poorly differentiated gastric- cancer cells as well as in non-cancerous tissue adjacent to poorly dif ferentiated gastric cancer, but no hybridization was detected in norma l epithelial cells adjacent to well-differentiated gastric cancer. The se findings may provide new information on HMG-1 mRNA expression in hu man gastrointestinal cancer and suggest a correlation between FMI mRNA expression to the differentiation and the stage of human gastrointest inal adenocarcinomas. (C) 1997 Wiley-Liss, Inc,..