Pim-2 Activates API-5 to Inhibit the Apoptosis of Hepatocellular Carcinoma Cells Through NF-κB Pathway Ke Ren & Wei Zhang & Yujun Shi & Jianping Gong Received: 4 August 2009 / Accepted: 24 September 2009 / Published online: 12 October 2009 # Arányi Lajos Foundation 2009 Abstract Pim-2 is proved to be relevant to the tumorigenesis of hepatocellular carcinoma (HCC), but the mechanism is unclear. We studied the relationship among Pim-2, NF-κB and API-5. In our experiment, expression level of the three factors and phosphorylation level of API-5, as well as NF-κB activity, were detected in HCC tissues and the nontumorous controls. Then Pim-2 gene was transfected into nontumorous liver cells L02, and Pim-2 SiRNA was transfected into hepatoblastoma cell line HepG2. Parthenolide was added as NF-κB inhibitor. The same detections as above were repeated in the cells, along with the apoptosis analysis. We found the levels of Pim-2, NF-κB and API-5, as well as NF-κB activity, were signifi- cantly higher in HCC tissues. Pim-2 level was increased in L02 cells after the transfection of Pim-2 gene, but decreased in HepG2 cells after the transfection of Pim-2 SiRNA. The levels of NF-κB and API-5, as well as NF-κB activity and API-5 phosphorylation level, were in accordance with Pim-2 level, but could be reversed by Parthenolide. Cell apoptosis rates were negatively correlated with API-5 phosphorylation level. Therefore, we infer that Pim-2 could activate API-5 to inhibit the apoptosis of liver cells, and NF-κB is the key regulator. Keywords Pim-2 . NF-κB . API-5 . Hepatocellular carcinoma cells . Apoptosis Abbreviations Pim Proviral integration of Monoley virus HCC hepatocellular carcinoma NF-κB nuclear factor kappa B Bcl-2 B-cell CLL/lymphoma 2 Bad Bcl2-antagonist of cell death API-5 apoptosis inhibitor 5 PNL paired noncancerous liver tissues NL normal liver tissues DEPC diethyl pyrocarbonate SDS- PAGE sodium dodecyl sulfate polyacrylamide gel electropheresis EMSA Electrophoretic mobility shift assay eI4B Eukaryotic initiation factor 4B Myc myelocytomatosis Introduction The disorder of cell proliferation and apoptosis induced by the activation of oncogene and the inactivation of antioncogene are two basic molecular biological events of tumorigenesis. Oncogene Pim-2 (Proviral integration of Monoley virus) was firstly discovered in lymphoma by Breuer in 1989 [1], its protein production is a kind of serine/threonine kinase. Pim-2 protein has powerful and extensive anti-apoptotic effect, and has been proved to play an important role in the tumorigenesis of many kinds of tumors such as hematopoi- etic system tumors and prostate cancer [2–4]. Our previous research has found that the expression level of Pim-2 was significantly higher in hepatocellular carcinoma (HCC) tissues and liver cancer cell line than that in the nontumorous K. Ren : W. Zhang : J. Gong Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, People’ s Republic of China Y. Shi West China Hospital of Sichuan University, Chengdu, People’ s Republic of China J. Gong (*) Department of Hepatobiliary Surgery, The Second College of Clinical Medicine and The Second Affiliated Hospital of Chongqing Medical University, 76# Linjiang Road, Chongqing 400010, People’ s Republic of China e-mail: gongjianping11@126.com Pathol. Oncol. Res. (2010) 16:229–237 DOI 10.1007/s12253-009-9215-4