The most promising of these candidate genes were: (i) PRKCA, PRKDC, and MCM4, as a functional relation to MSH2 is predicted by network analysis, and (ii) CSMD1, as this is commonly mutated in CRC.
Transient knockdown followed by cell proliferation assays were performed to validate the essentiality of PRKDC (Protein Kinase, DNA-Activated, Catalytic Polypeptide) in CRC.
Tumor tissues and adjacent normal tissues in 12 colorectal cancers were examined for quantitative differences in: i) activity of DNA-dependent protein kinase (DNA-PK), which functions in DNA double-strand breads repair, and ii) protein and mRNA levels of Ku70, Ku80, DNA-PKcs and transcriptional factor Sp1.