Isolation of Two Novel Genes, Down‐regulated in Gastric Cancer

Using a differential display technique, we identified two genes that are down‐regulated in human gastric cancer tissue as compared to normal gastric mucosa. The down‐regulated expression of these genes in gastric cancer tissue was confirmed by northern blotting analysis and RT‐PCR. One, CA11, was a novel gene expressed predominantly in the stomach and was depleted in all of the gastric cancer cell lines examined. The other gene, GC36, was homologous to the digestive tract‐specific calpain gene, nCL‐4. The expression of both GC36 and nCL‐4 was suppressed or depleted in gastric cancer cell lines of differentiated and poorly differentiated types. This is the first report of genes, the expression of which is down‐regulated with considerable frequency in gastric cancer.