Figure 3.

Effects of the ataxia telangiectasia mutated (ATM) inhibition on cisplatin‐induced human nucleus pulposus (hNP) cellular senescence. (a) SA‐β‐gal activity staining of hNP cell cultures treated with cisplatin with or without KU55933 for 24 hr followed by 6 days in drug‐free media. Graph shows the percentage of SA‐β‐gal‐positive cells. (b) KU55933 treatment decreased cisplatin‐induced p‐ATM (green) and γH2AX (red) immunofluorescence in hNP cells treated with cisplatin with or without KU55933 for 60 min. DAPI, nuclear stain (blue). Images were taken at 400X. Scale bars, 10μm. (c) Western analysis for senescence markers (p53, p21) in extracts from hNP cells treated with 50μM cisplatin for 24 hr with 2μM KU55933 or ATM siRNA. The protein levels were normalized against β‐actin, and graph shows average values ± SD. (n = 4), * p < .05 versus. control