Objective       To determine the role and the underlying mechanisms of xeroderma pigmentosum group C (XPC) in ultraviolet (UV) DNA damage response of human bladder cancer cell line T24.       Methods       XPC siRNA was used to induce T24 cells with stable XPC knockdown

and the obtained cells were confirmed by Western blotting. CCK-8 kit was employed to detect the inhibitory effects of UV on the T24 cells and T24 cells with XPC knockdown. The ability of DNA repair was evaluated by host-cell reactivation (HCR) assay. The nuclear recruitment of p-ATM towards the damaged DNA was determined by immunofluoresence staining.       Results       The T24 ce

lls with stable XPC knockdown were successfully established. Compared to the normal T24 cells

the XPC knockdown cells were more sensitive to UV treatment (

P

0.01)

showed declined ability of DNA repair (

P

0.01)

and reduced nuclear concentration of p-ATM towards the damaged DNA（

P

0.01).       Conclusion       XPC play a major role in DNA repair via affecting the nuclear recruitment of p-ATM in T24 cells.