Influence of RNA interference in p53 gene on the expressions of genes involved in ultraviolet B-induced premature senescence and photocarcinogenesis in human skin fibroblasts

Abstract

Objective To evaluate the effect of RNA interference in p53 gene on the expressions of genes involved in ultraviolet B (UVB)-induced premature senescence and photocarcinogenesis in human skin fibroblasts (HSFs).Methods A previously established HSF cell clone with repressed expression of p53,which was named as HSF-p53,was cultured and irradiated with a subcytotoxic dose (10 mJ/cm2) of UVB once a day for five consecutive days.The HSFs with normal expression of p53 served as the control.Subsequently,β-galactosidase (SA-β-gal)-staining was performed to estimate the degree of senescence,quantitative real-time PCR array was performed to determine the mRNA expressions of photocarcinogenesis-and senescence-associated genes,including p53,p21,p19,p16,pRb,fibronectin,osteonectin,smooth muscle 22 (SM22),bax,bcl-2,hypoxia-inducible factor-1 α (HIF-1α),vascular endothelial growth factor(VEGF),and human double minute-2 (hdm2).Statistical analysis was carried out by Student's t test using the software SPSS 10.0.Results The percentage of SA-β-gal-positive cells in irradiated HSF-p53 was 19.70％ ± 0.85％,significantly higher than that in unirradiated HSF-p53 (12.77％ ± 0.81％,t =6.45,P ＜ 0.05),but lower than that in irradiated control HSFs (50.48％ ± 5.30％,t =7.86,P ＜ 0.05),and similar to that in unirradiated control HSFs (18.50％ ± 0.45％,t =2.57,P ＞ 0.05).Compared with the control HSFs,the HSF-p53 showed decreased expressions of p21,p19,fibronectin,osteonectin,SM22 and bax genes (all P ＜ 0.05),but increased expressions of bcl-2,HIF-1α,VEGF and hdm2 genes (all P ＜ 0.05),and a similar expression of p16 gene (P ＞ 0.05); the repeated UVB radiation significantly promoted the expressions of p16 and pRb genes (both P ＜ 0.05),but had no obvious effect on the expressions of the other genes in HSF-p53 compared with unirradiated HSF-p53 (all P ＞ 0.05).Conclusions The inhibition of p53 expression may decelerate the UVB-induced premature senescence in HSFs,which may be involved in the p53-dependent tumor suppression. Key words: Genes, p53; RNA interference; Aging, premature; Ultraviolet rays; Fibroblasts