title: In vitro study on role of Hsp70 expression in DNA damage of human embryonic lung cells exposed to Benzo[a]pyrene.
abstract: OBJECTIVE
  Benzo[a]pyrene (B[a]P), a ubiquitous environmental pollutant, is a potent procarcinogen and mutagen that can elicit tumors, leading to malignancy. Heat shock proteins (Hsp) have been shown to protect cells against damages caused by various stresses including exposure to numerous chemicals. Whether Hsps, or more specifically Hsp70, are involved in repair of B[a]P-induced DNA damage is currently unknown.
  
  
  METHODS
  We assessed the potential role of the inducible form of Hsp70 in B[a]P-induced DNA damage of human embryonic lung (HEL) cells using immunoblot and the comet assay (i.e., the single cell gel electrophoresis assay).
  
  
  RESULTS
  Exposure to B[a]P induced a dose-dependent decrease in the level of Hsp70, but a dose-dependent +-increase in DNA damage both in untreated (control) HEL cells and in cells preconditioned by a heat treatment. Heat preconditioning prior to B[a]P exposure potentiated the effect of B[a]P at a low dose (10 micromol/L), but appeared to be protective at higher doses. There was a negative correlation between Hsp70 level and DNA damage in the non-preheated as well as in the preconditioned cells.
  
  
  CONCLUSIONS
  These data suggest that exposure of HEL cells to B[a]P may induce a dose-dependent reduction in the levels of the inducible Hsp70. The detailed mechanisms for the reduction of Hsp70 levels by B[a]P and the role of Hsp70 in DNA damage under different concentrations of B[a]P remains to be determined.
authors.affiliation: Institute of Occupational Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei, China.
authors.forename: Ya-Juan
authors.initials: YJ
authors.lastname: Gao
authors.forename: Cheng-Feng
authors.initials: CF
authors.lastname: Xiao
authors.forename: Sheng
authors.initials: S
authors.lastname: Chen
authors.forename: Rui-Bo
authors.initials: RB
authors.lastname: Wang
authors.forename: Han-Zhen
authors.initials: HZ
authors.lastname: He
authors.forename: Robert M
authors.initials: RM
authors.lastname: Tanguay
authors.forename: Tang-Chun
authors.initials: TC
authors.lastname: Wu
mesh_terms: D001564:Benzo(a)pyrene; D015153:Blotting, Western; D002274:Carcinogens, Environmental; D002478:Cells, Cultured; D020552:Comet Assay; D004247:DNA / Q000187:drug effects; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans
chemical_list: D002274:Carcinogens, Environmental; D018840:HSP70 Heat-Shock Proteins; D001564:Benzo(a)pyrene; D004247:DNA