Polypyrimidine tract-binding protein (PTBP1, also named hnRNP I) is a RNA-binding protein which has multiple functions related to the wide range of RNA metabolisms. Although several reports have shown that PTBP1 expression level is altered in various cancer types, the role of PTBP1 in hepatocellular carcinoma (HCC) is unknown. Here, I report that PTBP1 is substantially upregulated in human HCC and the patients highly expressing PTBP1 survived shorter than one with lower expression. Consistently, silencing PTBP1 by siRNA in HCC cell-line Hep3B cells induced growth arrest at G1 phase, suppressed colony forming ability of Hep3B, and decreased levels of pivotal cell cycle regulators including cyclin D1 and D3 and cyclin-dependent kinase 6 (cdk6).
Ribonucleoprotein immunoprecipitation analyses showed that PTBP1 associated with their mRNAs. Furthermore, PTBP1 expression in Hep3B cells was downregulated
by miR-194, whose expression was reduced in human HCC patients. Taken together, these findings suggest that PTBP1 contributes to liver cancer progression. Thus, modulation of PTBP1 might be a novel therapeutic strategy
against liver cancer.
