title: Vitamin K analog (compound 5) induces apoptosis in human hepatocellular carcinoma independent of the caspase pathway.
abstract: A systemic vitamin K analog, compound 5 (Cpd 5), possesses the ability to inhibit cell growth of tumor cells. Therefore, we investigated the effect of Cpd 5 in human hepatocellular carcinoma (HCC) cell lines and evaluated its role in apoptosis. Human HCC cell lines were cultured and treated with Cpd 5. Apoptosis was assessed using DAPI staining and Annexin-V membrane staining. The expression of caspases, XIAP and Bcl-xL was also investigated. Cpd 5 decreased cell viability in a dose-dependent manner in two HCC cells (HLE and SK-Hep1) containing mutant p53, but not in the HepG2 cell line, which contained wild-type p53. Cpd 5-treated HLE and SK-Hep1 cells showed typical apoptotic features, nuclear condensation and nuclear fragmentation upon DAPI staining. Positive membranous staining for Annexin-V was also seen in these cells. Both caspase-8 and caspase-3 activities were up-regulated slightly. Pro-caspase-8 protein levels decreased slightly in both cells. Although the expression of Bcl-xL was not influenced by Cpd 5, that of XIAP decreased in HLE cells. However, the pan-caspase inhibitor, zVAD, could not significantly prevent Cpd 5-induced apoptosis and Cpd 5 could not augment TRAIL-induced apoptosis. These results demonstrate that Cpd 5 induced apoptosis in human HCC cell lines, mainly independently of caspase activities. This may contribute to its highly potent cytotoxicity toward HCC cells.
authors.affiliation: First Department of Internal Medicine, Mie University School of Medicine, Mie, Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Enokimura
authors.forename: Katsuya
authors.initials: K
authors.lastname: Shiraki
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kawakita
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Saitou
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Inoue
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Okano
authors.forename: Norihiko
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Kazushi
authors.initials: K
authors.lastname: Sugimoto
authors.forename: Brian I
authors.initials: BI
authors.lastname: Carr
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakano
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D008562:Membrane Glycoproteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014812:Vitamin K / Q000031:analogs & derivatives* / Q000494:pharmacology; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: C446520:2-(2-hydroxyethylsulfanyl)-3-methyl-1,4-naphthoquinone; D051017:Apoptosis Regulatory Proteins; C494811:BCL2L1 protein, human; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D008562:Membrane Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D016159:Tumor Suppressor Protein p53; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D051020:bcl-X Protein; D014812:Vitamin K; D020169:Caspases