title: Tributyltin induces G2/M cell cycle arrest via NAD(+)-dependent isocitrate dehydrogenase in human embryonic carcinoma cells.
abstract: Organotin compounds, such as tributyltin (TBT), are well-known endocrine-disrupting chemicals (EDCs). We have recently reported that TBT induces growth arrest in the human embryonic carcinoma cell line NT2/D1 at nanomolar levels by inhibiting NAD(+)-dependent isocitrate dehydrogenase (NAD-IDH), which catalyzes the irreversible conversion of isocitrate to α-ketoglutarate. However, the molecular mechanisms by which NAD-IDH mediates TBT toxicity remain unclear. In the present study, we examined whether TBT at nanomolar levels affects cell cycle progression in NT2/D1 cells. Propidium iodide staining revealed that TBT reduced the ratio of cells in the G1 phase and increased the ratio of cells in the G2/M phase. TBT also reduced cell division cycle 25C (cdc25C) and cyclin B1, which are key regulators of G2/M progression. Furthermore, apigenin, an inhibitor of NAD-IDH, mimicked the effects of TBT. The G2/M arrest induced by TBT was abolished by NAD-IDHα knockdown. Treatment with a cell-permeable α-ketoglutarate analogue recovered the effect of TBT, suggesting the involvement of NAD-IDH. Taken together, our data suggest that TBT at nanomolar levels induced G2/M cell cycle arrest via NAD-IDH in NT2/D1 cells. Thus, cell cycle analysis in embryonic cells could be used to assess cytotoxicity associated with nanomolar level exposure of EDCs.
authors.affiliation: Division of Pharmacology, National Institute of Health Sciences.
authors.forename: Miki
authors.initials: M
authors.lastname: Asanagi
authors.forename: Shigeru
authors.initials: S
authors.lastname: Yamada
authors.forename: Naoya
authors.initials: N
authors.lastname: Hirata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Itagaki
authors.forename: Yaichiro
authors.initials: Y
authors.lastname: Kotake
authors.forename: Yuko
authors.initials: Y
authors.lastname: Sekino
authors.forename: Yasunari
authors.initials: Y
authors.lastname: Kanda
mesh_terms: D047310:Apigenin / Q000494:pharmacology; D018236:Carcinoma, Embryonal / Q000473:pathology*; D045744:Cell Line, Tumor; D056744:Cyclin B1 / Q000378:metabolism / Q000502:physiology; D052244:Endocrine Disruptors / Q000633:toxicity*; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D007523:Isocitrates / Q000378:metabolism; D007656:Ketoglutaric Acids / Q000378:metabolism / Q000494:pharmacology; D014220:Trialkyltin Compounds / Q000633:toxicity*; D020687:cdc25 Phosphatases / Q000378:metabolism / Q000502:physiology
chemical_list: C534699:CCNB1 protein, human; D056744:Cyclin B1; D052244:Endocrine Disruptors; D007523:Isocitrates; D007656:Ketoglutaric Acids; D014220:Trialkyltin Compounds; C011559:tributyltin; D047310:Apigenin; C034219:isocitric acid; D007521:Isocitrate Dehydrogenase; C517009:CDC25C protein, human; D020687:cdc25 Phosphatases