Skip to main content
Figure 3 | BMC Cancer

Figure 3

From: Decreased transcription-coupled nucleotide excision repair capacity is associated with increased p53- and MLH1-independent apoptosis in response to cisplatin

Figure 3

RNAi against CSB in DNA mismatch repair corrected HCT116 cells. (A) The effectiveness of siRNAs against CSB in HCT116 and HCT116 + chr3 cells was assessed by immunoblot analysis of nuclear lysates from cells that were either mock-transfected (M) or transfected with the indicated siRNA (non-targeting control (NT) or CSB). HCT116 + chr3 cells express readily detectable MLH1 protein (A and B). The # denotes a non-specific band recognized by this antibody. (C) Host cell reactivation of a UV-damaged reporter gene was determined in non-targeting siRNA (NT) and CSB siRNA (CSB) transfected HCT116 + chr3 cells. Reduced CSB levels were associated with a decrease in the dose required to reduce β-galactosidase activity to 50% (P < 0.05, t-test). (D) The ability of mock-, NT- and CSB-siRNA transfected HCT116 + chr3 cells to recover nascent RNA synthesis following UV exposure was assessed in HCT116 + chr3 cells. (E) Similarly transfected HCT116 + chr3 cells were exposed to the indicated dose of cisplatin and apoptosis was assessed as the proportion of cells with subdiploid DNA content 48 hours later. (F-H) The activity of caspases 3, 8 and 9 was determined 24 hours following exposure to 10 μM cisplatin. Each value in C-H represents the mean (± SEM) determined from a minimum of 3 independent experiments. An * in D indicates that the value is significantly less than 100% (P ≤ 0.05, single sample t-test) while an * in E indicates that the value is significantly different from its respective NT control (P ≤ 0.05, t-test). There was a significant difference in caspase 3, 8 and 9 activity among transfectants following cisplatin treatment (P = 0.001, 0.03 and 0.05, respectively, ANOVA). Similar results were obtained following exposure to UV light (data not shown).

Back to article page