Hepatopoietin Cn suppresses apoptosis of human hepatocellular carcinoma cells by up-regulating myeloid cell leukemia-1.
OBJECTIVE
To investigate the role of hepatopoietin Cn (HPPCn) in apoptosis of hepatocellular carcinoma (HCC) cells and its mechanism.


METHODS
Two human HCC cell lines, SMMC7721 and HepG2, were used in this study. Immunostaining, Western blotting and enzyme linked immunosorbent assay were conducted to identify the expression of HPPCn and the existence of an autocrine loop of HPPCn/HPPCn receptor in SMMC7721 and HepG2. Apoptotic cells were detected using fluorescein isothiocyanate (FITC)-conjugated Annexin V and propidium iodide.


RESULTS
The HPPCn was highly expressed in human HCC cells and secreted into culture medium (CM). FITC-labeled recombinant human protein (rhHPPCn) could specifically bind to its receptor on HepaG2 cells. Treatment with 400 ng/mL rhHPPCn dramatically increased the viability of HCC-derived cells from 48.1% and 36.9% to 85.6% and 88.4%, respectively (P < 0.05). HPPCn silenced by small-interfering RNA reduced the expression and secretion of HPPCn and increased the apoptosis induced by trichostatin A. Additionally, HPPCn could up-regulate the expression of myeloid cell leukemia-1 (Mcl-1) in HCC cells via mitogen-activated protein kinase (MAPK) and sphingosine kinase-1.


CONCLUSIONS
HPPCn is a novel hepatic growth factor that can be secreted to CM and suppresses apoptosis of HCC cells by up-regulating Mcl-1 expression.
Chang
Jing
J
Department of Experimental Hematology, Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China.
Liu
Yang
Y
Zhang
Dong-Dong
DD
Zhang
Da-Jin
DJ
Wu
Chu-Tse
CT
Wang
Li-Sheng
LS
Cui
Chun-Ping
CP
D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D017228:Hepatocyte Growth Factor / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects*; D000099157:Sphingosine Kinase
D017228:Hepatocyte Growth Factor; D006877:Hydroxamic Acids; D020929:Mitogen-Activated Protein Kinase Kinases; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D017853:Phosphotransferases (Alcohol Group Acceptor); D011500:Protein Synthesis Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D019859:Proto-Oncogene Proteins c-met; D011994:Recombinant Proteins; D000099157:Sphingosine Kinase; C012589:trichostatin A