Overexpression of eEF1A1 regulates G1-phase progression to promote HCC proliferation through the STAT1-cyclin D1 pathway

Hepatocellular carcinoma (HCC) is a common cancer worldwide with an aggressive and highly proliferative activity. Studies had confirmed that HCC cell proliferation is associated with the cell cycle's G1 phase, but the detailed molecular mechanism has not been thoroughly elucidated to date. Eukaryotic translation elongation factor 1A1 (eEF1A1) is an evolutionarily conserved elongation factor protein and is involved in tumor cell proliferation. However, which phase of the cell cycle is regulated by eEF1A1 to influence cell proliferation in HCC and its detailed molecular mechanism remain unclear. In this study, we observed that eEF1A1 influences HCC cell proliferation by regulating the cell cycle's G1 phase. In addition, eEF1A1 influences G1 phase by regulating cyclin D1 expression, promoting HCC cell proliferation both in vitro and in vivo. Moreover, our results indicated that eEF1A1 regulates cyclin D1 expression through STAT1 signaling. STAT1 increases the transcriptional activity of cyclin D1 by binding to the cyclin D1 promoter. Taken together, these findings enabled us to identify a novel mechanism by which eEF1A1 regulates the cell cycle's G1 phase to promote tumor proliferation by regulating cyclin D1 expression through STAT1 signaling in HCC. (C) 2017 Elsevier Inc. All rights reserved.