MDS.To solve these problems,a chemo-sensitization agent can be applied to increase the susceptibility of these cells to ATO.Curcumin (CUR),which possesses a wide range of anti-cancer activities,is a commonly used chemo-sensitization agent for various tumors,including hematopoietic malignancies.In this study,we investigated the cytotoxic effects and potential mechanisms in MDS-SKM-1 cells and leukemia stem-like KG1a cells treated with CUR and ATO alone or in combination.CUR and ATO exhibited growth inhibition by MTT assays and apoptosis by annexin V/PI analyses in both SKM-1 and KG1a cells.Apoptosis of SKM-1 and KG1a cells determined by annexin V/PI was significantly enhanced in the combination groups compared with the groups treated with either agent alone.Further evaluation was performed by Western blotting for two hallmark markers ofapoptosis,caspase-3 and cleaved-PARP.Co-treatment of the cells with CUR and ATO resulted in significant synergistic effects.In SKM-1 and KG1a cells,31 proteins and 13 proteins analyzed by protein array assays were modulated,respectively.Interestingly,survivin protein expression levels were down-regulated in both cell lines treated with CUR alone and in combination with ATO,especially in the latter case.Susceptibility to apoptosis was significantly increased in SKM-1 and KG 1 a cells treated with siRNA-survivin and ATO.These results suggested that CUR could increase the sensitivity of SKM-1 and KG1a cells to ATO by down-regulating the expression of survivin.