Resistance to UV-induced cell-killing in nucleophosmin/B23 over-expressed NIH 3T3 fibroblasts: enhancement of DNA repair and up-regulation of PCNA in association with nucleophosmin/B23 over-expression.
Nucleophosmin/B23 was rapidly up-regulated after UV irradiation as p53, PCNA and c-Jun. UV induction of nucleophosmin/B23 was evidently increased at 3 h post-irradiation, and reached a maximum at 12 h, and remained high for at least 24 h. Over-expression of nucleophosmin/B23 made cells more resistant to UV-induced cell growth inhibition and death as compared with control vector-transfected cells through three main observations: cell growth/death percentage determination; clonogenic survival assay; and flow cytometric analysis. Moreover, nucleophosmin/B23 over-expressed cells had a greater capacity to repair UV-damaged reporter plasmid, indicating a higher nucleotide excision repair (NER) activity. Furthermore, PCNA, an essential component for DNA repair machinery, was correlated with nucleophosmin/B23 expression. Both protein level and promoter activity of PCNA were higher in nucleophosmin/B23 over-expressed cells than in control vector-transfected cells. On the other hand, treatment of cells with nucleophosmin/B23 antisense oligonucleotides decreased nucleophosmin/B23 and PCNA proteins, and potentiated the UV-induced cell killing. The effect of PCNA up-regulation may be one of the reasons that nucleophosmin/B23 over-expression made cells resistant to UV-induced growth inhibition and cell-killing.
Wu
Ming H
MH
Graduate Institute of Pharmacology, National Yang Ming University, Taiwan, Republic of China.
Chang
Jei H
JH
Yung
Benjamin Y M
BY
D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D015153:Blotting, Western; D016923:Cell Death / Q000528:radiation effects; D002455:Cell Division / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D004260:DNA Repair / Q000235:genetics*; D004307:Dose-Response Relationship, Radiation; D005434:Flow Cytometry; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D000090243:Nucleophosmin; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014466:Ultraviolet Rays; D015854:Up-Regulation / Q000528:radiation effects*
C000715570:Npm1 protein, mouse; D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger; D000090243:Nucleophosmin