Identification, characterization and expression analysis of a novel TPA (12-0-Tetradecanoylphorbol-13-Acetate) induced gene.

Abstract

Using oligonucleotide microarray, we have identified and cloned a novel gene that was induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in CD18 pancreatic cancer cells. In-silico analysis suggested localization of the gene product to the endoplasmic reticulum, thus we named it TPA induced Trans-Membrane Protein (TTMP). We found that TTMP is highly expressed in normal human pancreas, but has low expression in cancer cell lines. Confocal immunofluorescence microscopy localized TTMP to the endoplasmic reticulum. CD 18 and HeLa cells stably expressing TTMP inhibited cell proliferation. Conversely, siRNA duplexes targeted to TTMP in CD18 cells led to an increase in cell proliferation, as did clones expressing an in-frame N-terminal truncation of TTMP. Cell cycle analysis showed that TTMP induced a G1 phase arrest in pancreatic cancer cells. Finally, the promoter of TTMP was cloned, and basal activity was found to be dependent on Sp1.