cDNA expression array analysis of DNA repair genes in human glioma cells that lack or express DNA-PK

M059J cells provide the only example of DNA-PKcs (now known as PRKDC) defic iency in a human cell line. M059K cells, derived from the same tumor specim en, express PRKDC protein and activity and, together with M059J, provide a useful model in which to study the role of DNA-PK in cellular responses to DNA-damaging agents. Because these cells are of tumor origin, we used Atlas (TM) human cancer cDNA expression arrays to investigate possible differenti al expression of other DNA repair genes in control and irradiated samples. cDNA array results indicated differential expression of 14 genes. Northern blotting confirmed relatively greater expression of replication factor C 37 -kDa subunit mRNA in M059J cells compared to M059K cells and reduced expres sion of DNA ligase TV compared to ligase III in both cell lines independent of irradiation, These results suggest that other DNA repair proteins are a ltered in these cell lines and that repair mechanisms predicted from the st udy of normal tissues may be fundamentally altered in human cancer cells. ( C) 2000 by Radiation Research Society.