OBJECTIVETo investigate the effect of benzo[a] pyrene(BaP) on DNA damage and expression of genes involved in nucleotide excision repair[xeroderma pigmentosum group B, C, G(XPB, XPC, XPG) and excision repair cross-complementing 1 (ERCC1)] in lung cancer A549 cells.

METHODSCell survival was measured using MIT metabolic viability assay. Single cell gel assay was applied to determine the DNA damage and repair. The level of gene expression was measured by reverse transcription-polymerase chain reaction.

RESULTSThe cell survival decreased from 95.0% to 70.0% after 24 h treatment with BaP of varying concentration ranging 0.625-20.000 mumol/L. The cell survival decreased to 87.0% and 73.0% respectively after 12 h and 24 h treatment with 10 mumol/L BaP, with DNA damage gradually elevated. At 12 h after 24 h treatment, the cell survival further decreased to 59.0% and DNA damage became most serious. At 24 h after 24 h treatment, cell survival recovered to 71.0%, and damaged DNA was repaired gradually. XPB and XPC gene expression increased to 4.5-fold and 11.2-fold respectively compared with basal level at 24 h treatment or 12 h after 24 h treatment with 10 mumol/L BaP respectively. However, ERCC1 and XPG gene expression was inhibited in 24 h treatment period, then recovered gradually after treatment.

CONCLUSIONBenzo[a]pyrene could lead to DNA damage and expression level change of genes involved in nucleotide excision repair in lung cancer A549 cells.