title: The growth inhibition of hepatocellular and cholangiocellular carcinoma cells by gemcitabine and the roles of extracellular signal-regulated and checkpoint kinases.
abstract: We examined the effects of gemcitabine, a pyrimidine analogue, on hepatocellular carcinoma (HCC) and cholangiocellular carcinoma (CCC) cells. After HCC cells (HepG2, Hep3B, HLF and PLC/PRF/5) and CCC cells (HuCCT-1) were treated with gemcitabine, cellular growth, cell cycle, nuclear morphology and activity of signaling molecules were evaluated by WST-8 assays, flow cytometry analysis, Hoechst 33258 staining and Western blotting, respectively. We found that gemcitabine significantly inhibited the growth of HCC and CCC cells in a dose- and time-dependent manner. Gemcitabine induced cell cycle arrest at the G1 phase, however, the sub-G1 fraction was not observed and nuclear morphology did not indicate the induction of apoptosis. Gemcitabine induced differential activation of checkpoint kinases, Chk2 and Chk1, in HCC and CCC cells, respectively and gemcitabine activated extracellular signal-regulated kinase (ERK)1/2 in both cell types. After the cells were pretreated with a MEK inhibitor U0126, activations of these checkpoint kinases were abrogated and the cell death was enhanced. These results demonstrate that gemcitabine inhibited the growth of HCC and CCC cells by cell cycle arrest without apoptosis and that the ERK/Chk1/2 signaling pathway was in part responsible for the resistance to gemcitabine. Our findings shed light on treating patients with HCC and CCC by gemcitabine, especially when combined with a MEK inhibitor and Chk1/2 inhibitors.
authors.affiliation: Second Department of Internal Medicine, Tottori University School of Medicine, Tottori, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Takakazu
authors.initials: T
authors.lastname: Nagahara
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Okano
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Murawaki
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001650:Bile Duct Neoplasms / Q000188:drug therapy* / Q000473:pathology; D001653:Bile Ducts, Intrahepatic; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D018281:Cholangiocarcinoma / Q000188:drug therapy* / Q000473:pathology; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology*; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000473:pathology; D011494:Protein Kinases / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D003841:Deoxycytidine; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C000605867:CHEK1 protein, human; C578634:CHEK2 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D000093542:Gemcitabine