Abstract: BACKGROUND AND AIM: The associations between the changes of p63 and p73 in mRNA levels and the BaP-induced DNA damage in H1299 cells and in 16HBE cells were investigated. MATERIALS AND METHODS: Both H1299 cells and 16HBE cells were treated with BaP at various concentrations (8,16,32,64 and 128 μmol/L) for 4 h and 12 h.At the two time points, the levels of MDA、SOD and GSH-Px were measured using the test kits. The mRNA levels of p53,p63,p73,mdm2 and mdm4 genes were detected by RT-PCR assay. DNA damage in the cells were evaluated by Comet assay. RESULTS: At 4 h,enhanced MDA level was observed (P<0.05). However, levels of SOD and GSH-Px were significantly decreased(P<0.05 for both) in both kinds of cells. After 16HBE and H1299 cells were treated for 4 h and 12 h, DNA damage and mRNA expression levels of mdm2 and mdm4 genes increased in a dose-dependent manner(P<0.01 for all). But enhanced mRNA expression level of p53 was observed only at 12 h(P<0.01). In addition,significant up-regulation of p63 and p73 genes in mRNA levels at the two time points were observed in H1299 cells(P<0.05). CONCLUSION: The BaP-induced DNA damage may be associated with enhanced mRNA levels of p63 and p73 genes in the p53-null H1299 cells.

Key words: benzo(a)pyrene, DNA damage, p63 gene, p73 gene