title: Growth inhibition of human hepatocellular carcinoma cells by overexpression of G-protein-coupled receptor kinase 2.
abstract: Hepatocellular carcinoma (HCC) is one of the deadliest forms of human liver cancer and does not respond well to conventional therapies. Novel effective treatments are urgently in need. G-protein-coupled kinase 2 (GRK2) is unique serine/threonine kinase that involves in many signaling pathways and regulates various essential cellular processes. Altered levels of GRK2 have been linked with several human diseases including cancer. In this study, we investigated a novel approach for HCC treatment by inducing overexpression of GRK2 in human HCC cells. We found that overexpression of GRK2 through recombinant adenovirus transduction inhibits the growth of human HCC cells. BrdU incorporation assay showed that the growth inhibition caused by elevated GRK2 level was due to reduced cell proliferation but not apoptosis. To examine the anti-proliferative function of increased GRK2 level, we performed cell cycle analysis using propidium iodide staining. We found that the proliferation suppression was associated with G2/M phase cell cycle arrest by the wild-type GRK2 but not its kinase-dead K220R mutant. Furthermore, increased levels of wild-type GRK2 induced upregulation of phosphor-Ser(15) p53 and cyclin B1 in a dose-dependent manner. Our data indicate that the anti-proliferative function of elevated GRK2 is associated with delayed cell cycle progression and is GRK2 kinase activity-dependent. Enforced expression of GRK2 in human HCC by molecular delivery may offer a potential therapeutic approach for the treatment of human liver cancer.
authors.affiliation: Division of Transplantation, Department of Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA. zhengyu.wei@jefferson.edu
authors.forename: Zhengyu
authors.initials: Z
authors.lastname: Wei
authors.forename: Reginald
authors.initials: R
authors.lastname: Hurtt
authors.forename: Michele
authors.initials: M
authors.lastname: Ciccarelli
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Koch
authors.forename: Cataldo
authors.initials: C
authors.lastname: Doria
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D002417:Cattle; D059447:Cell Cycle Checkpoints; D049109:Cell Proliferation; D056744:Cyclin B1 / Q000378:metabolism; D054769:G-Protein-Coupled Receptor Kinase 2 / Q000235:genetics / Q000378:metabolism*; D005822:Genetic Vectors; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D009154:Mutation; D010766:Phosphorylation; D012694:Serine; D013997:Time Factors; D014161:Transduction, Genetic; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C534699:CCNB1 protein, human; D056744:Cyclin B1; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D012694:Serine; D054769:G-Protein-Coupled Receptor Kinase 2