|
pubmed:abstractText |
Human polynucleotide kinase (hPNK) is a 57.1-kDa monomeric protein with conserved motifs associated with phosphatase and kinase activities. hPNK catalyzes phosphorylation of 5'-DNA termini and dephosphorylation of 3'-DNA termini. Previous studies, employing cell-free systems, have suggested that hPNK participates in the repair of DNA strand breaks. To better define the cellular function of hPNK, a double-stranded small-interfering RNA molecule designed to stably target hPNK transcription was introduced into A549 human lung adenocarcinoma cells. The small-interfering RNA suppressed hPNK gene expression by at least 80-90%. These cells exhibited a 7-fold higher spontaneous mutation frequency based on the development of resistance to ouabain; elevated sensitivity to a broad range of genotoxic agents including gamma-radiation, UVC radiation, methyl methanesulfonate, hydrogen peroxide, and camptothecin; and slower repair of radiation-induced DNA strand breaks. These findings underscore the importance of hPNK in the maintenance of DNA integrity after damage induced by endogenous and exogenous agents.
|
|
pubmed:affiliation |
Department of Experimental Oncology, Cross Cancer Institute, University of Alberta, Edmonton, AB, Canada T6G 1Z2.
|
