PL 33. A novel gene regulates tumorigenesis at the transcriptional level

Tumorigenesis is caused by uncontrolled cell cycle progress and altered expression of many genes. Here we report a novel gene CREPT (cell-cycle related and expression- elevated protein in tumor) preferentially expressed in different human tumors. Over expression of CREPT results in rapid cell growth, promotes cell cycle transition from G1 to S phase, and accelerates growth of tumors while knocking down CREPT demonstrates reversed effects. CREPT regulates the expression of several cell cycle related genes and cyclin D1 is identified as a quickly responding gene. Further analysis reveals that CREPT specifically activates cyclin D1 transcription both in vivo and in vitro by enhancing RNA polymerase II binding to the cyclin D1 promoter and accelerates its release from the 3' end of the gene. Our findings suggest that CREPT is a novel oncoprotein regulating cell cycle by directly enhancing cyclin D1 transcription.