Down-regulation of DNA polymerases κ, η, ι, and ζ in human lung, stomach, and colorectal cancers

Human DNA polymerases κ, η, ι, and ζ are responsible for the translesion DNA synthesis. Numerous in vitro studies indicated that these enzymes may contribute to DNA lesion-triggered and spontaneous mutation. We measured the transcripts of these 4 enzymes in 131 self-paired cancerous and non-tumor samples, including 23 lung cancers, 49 stomach cancers, and 59 colorectal cancers. Our results indicated that, except pol η in colorectal cancers, these enzymes are all significantly down-regulated in human lung, stomach, and colorectal cancers, suggesting that these enzymes are probably not closely associated with the elevated mutations in human cancer.