Objective     To determine the effect of tubeimoside 1 (TBMS1) in enhancing chemosensitivity of drug-resistant ovarian cancer cell line (A2780/DDP) to cisplatin.     Methods    The A2780/DDP cells were treated with different concentrations of cisplatin and TBMS1 to analyze 50% inhibiting concentration (IC50) by methyl thiazolyl tetrazolium (MTT) assay. Experiment was divided into 4 groups. Control group: treatment with physiological saline; cisplatin group: treatment with 6 μmol/L cisplatin; Combination of drugs groupⅠ: 6 μmol/L cisplatin + 3 μmol/L TBMS1; Combination of drugs groupⅡ: 6 μmol/L cisplatin + 6 μmol/L TBMS1. After the cells were treated by the above methods

the cells viability was analyzed by MTT assay. The cellular DNA damage was measured by agarose gel electrophoresis. Apoptosis and cell cycles were measured by flow cytometry. The expression of Cyclin A and Cyclin D1 protein was determined by Western blotting.     Results    TBMS1 (3 and 6 μmol/L) combined with cisplatin (6 μmol/L) enhanced the chemosensitivity of A2780/DDP cells to cisplatin. After co-treatment with TBMS1

the level of cellular DNA damage was significantly increased with increase of TBMS1 concentration. Cell cycle was arrested in S phase

with a proportion of (51.23±3.53) % and (77.34±2.80)%

respectively for groupⅠ and group Ⅱ. Apoptosis ratio was (5.19±0.78)%

and (7.11±1.06)% respectively

Cyclin A expression of was 1.89±0.28 and 2.91±0.43 respectively

while that of Cyclin D1 was 0.66±0.09 and 0.28±0.05 respectively for the 2 groups (P0.01

0.05).     Conclusion    TBMS1 inhibits the growth of A2780/DDP cells and enhances the sensitivity to cisplatin

and Cyclin A and Cyclin D1 might be involved in the processes.