title: Involvement of hemeoxygenase-1 in di(2-ethylhexyl) phthalate (DEHP)-induced apoptosis of Neuro-2a cells.
abstract: A widely-used plasticizer di(2-ethylhexyl) phthalate (DEHP) is known to induce apoptosis in neurons, although the mechanisms responsible for DEHP-induced apoptosis is not well explored yet. We recently showed that exposure to DEHP increases the expression of hemeoxygenase (HO)-1, an oxidative stress related enzyme, in the mice brain. In this study, we investigated whether HO-1 is involved in DEHP-induced apoptosis using a mouse neuroblastoma cell line Neuro-2a, which forcibly express SCAT3, a fluorescent indicator of caspase-3 activity. The doses of DEHP at 1, 10 or 100 µM were used in the present study to mimic the level of human exposure to DEHP. Live image analysis of SCAT3-expressing Neuro-2a cells revealed that caspase-3 activity in the cells was significantly increased by DEHP at 100 µM but not 1 or 10 µM. We measured HO-1 mRNA level in Neuro-2a cells exposed to DEHP and found significant increase in HO-1 mRNA level by DEHP at 100 µM but not 1 or 10 µM. Live image analysis of SCAT3-expresisng Neuro-2a cells was further performed to determine the effects of HO-1 siRNA in DEHP-induced apoptosis via caspase-3 activation. We found that knockdown of HO-1 gene nullifies the effects of DEHP to activate caspase-3. These results suggest that HO-1 is involved in DEHP-induced apoptosis. Moreover, this study demonstrates that high-dose DEHP exposure induces caspase-3-dependent apoptosis, which is at least partially mediated by the up-regulation of HO-1 gene, in Neuro-2a cells.
authors.affiliation: Division of Life Science, Graduate School of Science and Engineering, Saitama University.
authors.forename: Kyaw Htet
authors.initials: KH
authors.lastname: Aung
authors.forename: Tin-Tin
authors.initials: TT
authors.lastname: Win-Shwe
authors.forename: Moeko
authors.initials: M
authors.lastname: Kanaya
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Takano
authors.forename: Shinji
authors.initials: S
authors.lastname: Tsukahara
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics*; D053148:Caspase 3 / Q000378:metabolism / Q000502:physiology; D045744:Cell Line, Tumor; D004051:Diethylhexyl Phthalate / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D055785:Gene Knockdown Techniques; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D057054:Molecular Imaging; D009447:Neuroblastoma / Q000201:enzymology / Q000473:pathology*; D010968:Plasticizers / Q000633:toxicity*; D012333:RNA, Messenger / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D010968:Plasticizers; D012333:RNA, Messenger; D004051:Diethylhexyl Phthalate; D051547:Heme Oxygenase-1; D053148:Caspase 3