In vitro study on role of Hsp70 expression in DNA damage of human embryonic lung cells exposed to Benzo[a]pyrene.
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.
Gao
Ya-Juan
YJ
Institute of Occupational Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei, China.
Xiao
Cheng-Feng
CF
Chen
Sheng
S
Wang
Rui-Bo
RB
He
Han-Zhen
HZ
Tanguay
Robert M
RM
Wu
Tang-Chun
TC
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
D002274:Carcinogens, Environmental; D018840:HSP70 Heat-Shock Proteins; D001564:Benzo(a)pyrene; D004247:DNA