Studies For The Antitumor Effects Of Decitabine And Bortezomib On RPMI 8226 Cell Line

Objectives: To investigate potential combined effects of bortezomib(BTZ) and decitabine(DAC) on human multiple myeloma cell line RPMI8226.Methods: Human multiple myeloma cell line RPMI8226 cells were treated with different concentration of BTZ 5nmol/L(5n M)、10nmol/L(10n M)、20nmol/L(20n M) in the presence or absence of DAC 0.5mmol/L(0.5m M) for 48 hours.Cellular morphology was observed by inverted phase contrast microscope; cell viability and proliferative inhibition ability were evaluated by Cell Counting Kit-8 assay; the apoptosis rate and cell cycle changes were examined by flow cytometry(FCM); the expression of apoptosis related proteins caspase-3, caspase-9 and PARP-1 was detected by Western blot method.Results:(1) Inverted phase contrast microscope showed that, compared with control group, cell density of BTZ or DAC single group was decreased and cellular debris began to emerge. This observation was more obvious in the combined group.(2) In the BTZ single drug group, with the increasing concentration, the rate of cell viability decreased gradually(p<0.05). When BTZ was combined with DAC, the rate decreased more significantly(p<0.05). Similarly, the BTZ combined with DAC group showed more inhibition of RPMI 8266 cell proliferation than single drug group. According to the King’s formula, BTZ(5n M,10 n M) and DAC(0.5m M) showed synergistic effect, while BTZ(20n M) and DAC(0.5m M) exhibited additive effect with each other.(3) The apoptosis rate of cells was increased after treatment by increasing concentration of BTZ(p<0.05). When BTZ combined with DAC, the apoptosis-inducing effect was more significant(p<0.05).(4) Exposure to BTZ induced dose-dependantly cell cycle arrest in myeloma cells(p<0.05). A combination of BTZ with DAC can enhance the cell cycle arrest effects of BTZ(p<0.05).(5) Cleavage of PARP-1, caspase-9 and caspase3 was observed in BTZ-treated cells, which was signifiantly increased in the combination group.Conclusion:(1) Both BTZ and DAC can induce proliferation inhibition, apoptosis and G0-G1 arrest in myeloma cell line RPMI8226.(2) Combination of these two drug exhibits either synergistic or additive effect according to the different concentrateion of BTZ.(3) DAC may enhance the apoptosis-inducing effect of BTZ by activation of poptosis related proteins caspase-3, caspase-9 and PARP-1.