title: Benzo[a]pyrene exposed to solar-simulated light inhibits apoptosis and augments carcinogenicity.
abstract: Polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (BaP) are widespread environmental pollutants and several lines of experimental evidence have suggested a role in carcinogenesis. PAHs in the environment are exposed to sunlight and photomodified PAHs have been detected in contaminated sediment and air particulate matter; however, the carcinogenicity of photomodified PAHs is not well understood. In this study, we found that solar-simulated light-irradiated BaP (LBaP) inhibited apoptosis, leading to cancer. LBaP suppressed apoptosis induced by cell detachment and serum depletion in a dose and light-irradiated time-dependent manner. The antiapoptotic effect was related to the production of reactive oxygen species from degraded BaP. The cells that survived apoptosis by LBaP treatment were transformed having the ability to form colonies in soft agar and tumors in nude mice. These capabilities were specific to LBaP, not BaP itself. The results suggested that the carcinogenicity of PAHs may be attributable not only to the genetic damage induced by their metabolites, but also to the antiapoptotic effects of oxidative products on exposure to sunlight.
authors.affiliation: Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Suruga-ku, Shizuoka-shi, Japan. teranishim@pref.tottori.jp
authors.forename: Mai
authors.initials: M
authors.lastname: Teranishi
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Toyooka
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ohura
authors.forename: Shuichi
authors.initials: S
authors.lastname: Masuda
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ibuki
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects*; D001564:Benzo(a)pyrene / Q000494:pharmacology*; D002273:Carcinogens / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D041681:NIH 3T3 Cells; D017382:Reactive Oxygen Species / Q000378:metabolism; D013472:Sunlight
chemical_list: D002273:Carcinogens; D017382:Reactive Oxygen Species; D001564:Benzo(a)pyrene