OBJECTIVE:To investigate the mechanism of hon-okiol (HNK) on bladder cancer cells and its synergis-tic anticancer effect with hydroxycamptothecin(HCPT).METHODS:Control,HNK,HCPT,and HNK plus HCPT groups were established.The morphological characteristics of T24 cells were examined micro-scopically.The maximal experimental concentra-tion of HNK and HCPT were determined according to IC10 detected by MTT.T24 cell viability and the percentage of apoptotic cells were assessed on the basis of MTT and flow cytometric analysis.The ex-pression of caspase-3,caspase-9,phosphorylated nuclear factor-kappa B (NF-κB)-p65,Akt,and extra-cellular signal-regulated kinase (ERK) proteins were analyzed by Western blot.RESULTS:Apoptosis in T24 cells was observed mi-croscopically in both the HNK and HCPT groups and even more obvious in the HNK plus HCPT groups.The percentage of T24 cell viability de-creased down to 19.41％,and the percentage of apoptotic cells rose to 54.08％ when treated with HNK plus HCPT in an HNK dose-dependent man-ner.The induction of caspase-3 and caspase-9 pro-teins and the inhibition of phosphorylation of NF-κB-p65,Akt,and ERK proteins in T24 cells were demonstrated in the HNK groups,and more signifi-cantly in the HNK plus HCPT groups,but not in the HCPT group.CONCLUSION:The anticancer effect of HNK may be due to the activation of the caspase pathway and inhibition of phosphorylation of NF-KB,Akt,and ERK.HNK in combination with HCPT produces a synergistic cell-killing effect on bladder cancer cells.