HCPT downregulates the expression of survivin and XIAP and in colon cancer cells. (A) SW1116 cells were treated with 10-hydroxycamptothecin (HCPT) (2.5 μg/mL) for 48 hours. Expression of survivin, X-linked inhibitor of apoptosis protein (XIAP), c-inhibitor of apoptosis (IAP)-1 and c-IAP-2 were determined by western bot. (B) SW1116 cells were treated with HCPT for 48 hours. Expression of survivin splices was determined by real-time PCR; *P < 0.05, #P >0.05, compared to the control group. (C-D) Knockdown of survivin and XIAP by siRNA. SW1116 cells were transfected with Survivin siRNA (C), and XIAP siRNA (D). Twenty-four hours after transfection, cells were treated with HCPT for another 48 hours. The mRNA expression of survivin (C) and XIAP (D) was measured by real-time PCR. (E-F) Knockdown of survivin and XIAP enhanced HCPT-induced apoptosis. SW1116 cells were transfected with Survivin siRNA (E), and XIAP siRNA (F). Then, cells were treated with HCPT for another 48 hours. Apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining; *P < 0.01, compared to the control siRNA groups; *P < 0.01, compared to the PBS group.