[Effect of hyperoxia on p53 and PCNA expression in fetal rat lung fibroblasts].

Objective: To study the effect of hyperoxia exposure on the expression of p53 and proliferating cell nuclear antigen (PCNA) in fetal rat lung fibroblasts (LFs).

Methods: Primary rat embryonic LFs were cultured in vitro. LFs grew to subconfluence and then were randomly divided into air and hyperoxia exposure (95% O₂, 5% CO₂) groups. After LFs were cultured for 12 and 24 hours, the proliferation was analyzed by MTT. p53 mRNA level was detected by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). p53 and PCNA protein levels were determined by Western blot.

Results: After 12 and 24 hours of culture the growth inhibition rate of LFs was 8% and 23% respectively in the hyperoxia exposure group. p53 mRNA and protein levels increased significantly (P<0.01) in the hyperoxia exposure group after 12 and 24 hours of culture compared with the air exposure group. Hyperoxia exposure decreased PCNA expression after 24 hours of culture (P<0.01).

Conclusions: Hyperoxia exposure increases p53 level and decreases PCNA expression, resulting in inhibitions of LFs proliferation and DNA repair.