Expression of tumor suppressor p53 facilitates DNA repair but not UV-induced G2/M arrest or apoptosis in Chinese hamster ovary CHO-K1 cells.
Tumor suppressor p53 is an essential regulator in mammalian cellular responses to DNA damage including cell cycle arrest and apoptosis. Our study with Chinese hamster ovary CHO-K1 cells indicates that when p53 expression and its transactivation capacity was inhibited by siRNA, UVC-induced G2/M arrest or apoptosis were unaffected as revealed by flow cyotmetric analyses and other measurements. However, inhibition of p53 rendered the cells slower to repair UV-induced damages upon a plasmid as shown in host cell reactivation assay. Furthermore, the nuclear extract (NE) of p53 siRNA-treated cells was inactive to excise the UV-induced DNA adducts as analyzed by comet assay. Consistently, the immunodepletion of p53 also deprived the excision activity of the NE in the similar experiment. Thus, tumor suppressor p53 of CHO-K1 cells may facilitate removal of UV-induced DNA damages partly via its involvement in the repair mechanism.
Chang
Yu-Ching
YC
Institute of Molecular Medicine, National Tsing-Hua University, Hsin-Chu, Taiwan.
Liao
Chu-Bin
CB
Hsieh
Pei-Yu Chiang
PY
Liou
Ming-Li
ML
Liu
Yin-Chang
YC
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D016466:CHO Cells / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D002110:Caffeine / Q000494:pharmacology; D002460:Cell Line / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D006224:Cricetinae; D003412:Cricetulus; D004249:DNA Damage; D004260:DNA Repair; D005260:Female; D016195:G2 Phase / Q000528:radiation effects*; D018390:Gene Targeting; D016158:Genes, p53 / Q000187:drug effects; D006801:Humans; D008168:Lung; D008677:Metaphase / Q000528:radiation effects*; D034741:RNA, Small Interfering / Q000494:pharmacology; D013045:Species Specificity; D015533:Transcriptional Activation; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis / Q000502:physiology*; D014466:Ultraviolet Rays / Q000009:adverse effects*
D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D002110:Caffeine