Zoledronic acid induces apoptosis and S-phase arrest in mesothelioma through inhibiting Rab family proteins and topoisomerase II actions.
Zoledronic acid (ZOL), a nitrogen-containing bisphosphonate, produced anti-tumor effects through apoptosis induction or S-phase arrest depending on human mesothelioma cells tested. An addition of isoprenoid, geranylgeraniol but not farnesol, negated these ZOL-induced effects, indicating that the ZOL-mediated effects were attributable to depletion of geranylgeranyl pyrophosphates which were substrates for prenylation processes of small guanine-nucleotide-binding regulatory proteins (small G proteins). ZOL-treated cells decreased a ratio of membrane to cytoplasmic fractions in RhoA, Cdc42 and Rab6 but less significantly Rac1 proteins, indicating that these proteins were possible targets for ZOL-induced actions. We further analyzed which small G proteins were responsible for the three ZOL-induced effects, caspase-mediated apoptosis, S-phase arrest and morphological changes, using inhibitors for respective small G proteins and siRNA for Cdc42. ZOL-induced apoptosis is due to insufficient prenylation of Rab proteins because an inhibitor of geranlygeranyl transferase II that was specific for Rab family proteins prenylation, but not others inhibitors, activated the same apoptotic pathways that ZOL did. ZOL suppressed an endogenous topoisomerase II activity, which was associated with apoptosis and S-phase arrest in respective cells because we detected the same cell cycle changes in etoposide-treated cells. Inhibitors for geranlygeranyl transferase I and for RhoA produced morphological changes and disrupted actin fiber structures, both of which were similar to those by ZOL treatments. These data demonstrated that anti-tumor effects by ZOL were attributable to inhibited functions of respective small G proteins and topoisomerase II activity, and suggested that cellular factors were involved in the differential cell cycle changes.
1] Division of Pathology and Cell Therapy, Chiba Cancer Center Research Institute, Chiba, Japan [2] Department of Respirology, Graduate School of Medicine, Chiba University, Chiba, Japan.
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Okamoto
1] Division of Pathology and Cell Therapy, Chiba Cancer Center Research Institute, Chiba, Japan [2] Department of Molecular Biology and Oncology, Graduate School of Medicine, Chiba University, Chiba, Japan.
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Jiang
Division of Pathology and Cell Therapy, Chiba Cancer Center Research Institute, Chiba, Japan.
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Kawamura
Department of Thoracic Disease, Chiba Cancer Center, Chiba, Japan.
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Shingyoji
Department of Respirology, Graduate School of Medicine, Chiba University, Chiba, Japan.
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Tada
Department of Medical Oncology, Graduate School of Medicine, Chiba University, Chiba, Japan.
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Sekine
Department of Medical Oncology, Graduate School of Medicine, Chiba University, Chiba, Japan.
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Takiguchi
Department of Respirology, Graduate School of Medicine, Chiba University, Chiba, Japan.
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Tatsumi
Department of Biochemistry, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Japan.
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Kobayashi
Department of Surgery, School of Medicine, Toho University, Tokyo, Japan.
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Shimada
Department of Pathology, Tokyo Women's Medical University Yachiyo Medical Center, Chiba, Japan.
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Hiroshima
1] Division of Pathology and Cell Therapy, Chiba Cancer Center Research Institute, Chiba, Japan [2] Department of Molecular Biology and Oncology, Graduate School of Medicine, Chiba University, Chiba, Japan.
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Tagawa
D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000378:metabolism; D004164:Diphosphonates / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004224:Diterpenes / Q000494:pharmacology; D005204:Farnesol / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007093:Imidazoles / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008654:Mesothelioma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D017368:Protein Prenylation; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D016196:S Phase / Q000187:drug effects* / Q000235:genetics; D015398:Signal Transduction; D014166:Transferases / Q000235:genetics / Q000378:metabolism; D000077211:Zoledronic Acid; D020764:cdc42 GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
D004164:Diphosphonates; D004224:Diterpenes; C466792:GGTI 2147; D007093:Imidazoles; C579095:MCL1 protein, human; D064549:Myeloid Cell Leukemia Sequence 1 Protein; C107953:RAC1 protein, human; D034741:RNA, Small Interfering; C095279:Rab geranylgeranyl transferase beta-subunit; C094135:Rab6 protein; C066737:RHOA protein, human; D005204:Farnesol; D000077211:Zoledronic Acid; C017338:geranylgeraniol; D014166:Transferases; D020764:cdc42 GTP-Binding Protein; D020691:rab GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein; D004250:DNA Topoisomerases, Type II; D007930:Leucine