IL-8 depletion increases the cytotoxicity of chemotherapeutic drugs in AIPC cells. IL-8 siRNA or CsiRNA transfected PC-3 and DU145 cells were exposed to cytotoxic drugs, 24 h after transfection. Cell viability was evaluated 48 h later (72 h post-transfection) by MTT reduction assay. Cytotoxicity of all three drugs, Docetaxel, Staurosporine and Rapamycin were equally increased in both DU145 and PC-3 cells, indicating chemo-sensitization was not likely depended on the mechanism of cytotoxic drug activity but due to alteration in cell survival mechanism caused by IL-8 depletion. Results shown are Mean ± SEM from three independent experiments, normalized with respect to samples with or without drug treatment. Note: All cytotoxicity data are normalized with respect to the reduction in cell viability due to IL-8siRNA transfection. The cytotoxicity was significantly higher (p < 0.04) at all concentrations of Docetaxel, and Rapamycin in PC-3 and DU145 cells, with Staurosporine in DU145 cells and at highest concentration tested in for all drugs in both cell lines. We analyzed the cytotoxicity data by non-linear regression and tested the mean survival values by t-test.