FIGC, a novel FGF-induced ubiquitin-protein ligase in gastric cancers.

We have previously shown that fibroblast growth factor receptor 2 (FGFR2) plays an important role in gastric carcinogenesis. In this study, we have used a differential display approach to identify basic fibroblast growth factor (bFGF)-inducible genes in gastric cancer cells. Here, we report that one of these genes is predicted to encode a RING finger protein, designated FIGC. The FIGC gene was found to encode a polypeptide of 381 amino acids with a novel RING finger module at the NH2-terminus and the COOH-terminal proline-rich region. Using an in vitro ubiquitination assay with recombinant protein, we demonstrate that FIGC has intrinsic E3 ubiquitin ligase activity and promotes ubiquitination. Our data indicate that FIGC upregulation in response to bFGF in gastric cancer might be implicated in carcinogenesis through dysregulation of growth modulator.