[Identification of an abnormally over-expressed gene in human stomach cancer by differential screening].

A cDNA library was constructed from the tumor tissue of a case of poorly-differentiated adenocarcinoma of the stomach. It was differentially screened using two kinds of probes, one from the tumor tissue and the other from normal tissue of the stomach away from the tumor of the same patient. After two rounds of plaque screening, 4 clones were selected. The inserted cDNA fragments isolated from each of the 4 clones were used as probes in subsequent studies of 9 patients with gastric cancer of different histological types by RNA dot blot hybridization. It was found that one of the 4 clones of cDNA showed over-expression in the tumors from all patients. This cDNA fragment was referred to as human stomach cancer gene (hSCG-3) with a size of 0.45 kb. DNA sequencing indicated that hSCG-3 did not show sequence homology to any of the genes identified according to a search in the Genbank and EMBL (modified). Therefore, hSCG-3 can be considered as a hither to unidentified new oncogene.