The Non-homologous end-joining repair gene XRCC6/Ku70 plays an important role in the repair of DNA double-strand breaks (DSBs), and has been found to be involved in the carcinogenesis of many types of cancers including oral, prostate, breast and bladder cancer.
Among hazardous environmental bladder cancer risk factors, heavy consumption of coffee was associated with a twofold decreased Ku 70 and Ku 80 mRNA expression, whereas tobacco smoke did not substantially affect the activity of the Ku system, except for a trend towards a dose-response relationship in the expression of Ku 70 mRNA.