[Mechanisms of Astragalus Polysaccharids Synergized with Doxorubicin against Drug Resistance in HL-60/A Cells].

OBJECTIVE: To explore the synergistic anti-tumor mechanism of astragalus polysaccharids(APS) combined with doxorubicin in HL-60/A cells. METHODS: The phenotype of HL-60/A was identified by using RT-PCR, Wester blot and CCK-8, the antitumor effect of astragalus polysaccharids combined with doxorubicin on HL-60/A cells was detected by CCK-8, the apoptosis of HL-60/A after treating with different drugs was detected by Annexin-V, the caspase casade activation was detected by Wester blot, the effect of astragalus polysaccharids on expression and function of multidrug resistance protein (MRP) was detected by using real-time quantitative PCR and Western blot. RESULTS: HL-60/A cells displayed obvious characteristics of resistance to doxorubicin, whose resistance were about 27 times that of its sensitive cell line HL-60. In addition, it was further found that astragalus polysaccharids could obviously increase the cell growth inhibition, induce cell apoptosis and caspase cascade activation, decrease the expression of MRP and increase the drug concentration in HL-60/A when combined with doxorubicin. CONCLUSION: Astragalus polysaccharids combined with doxorubicin can effectively overcome the drug resistance of HL-60/A. The mechanism may be associated with decreasing the expression of MRP, inhibiting drug efflux and increasing the intracellular drug concentration, then inducing HL-60/A cell apoptosis.

[OATP1B1 in drug-drug interactions between traditional Chinese medicine Danshensu and rosuvastatin].

The study was designed to explore the drug-drug interactions mechanisms mediated by OATP1B1 between traditional Chinese medicine Danshensu and rosuvastatin. First, the changes of rosuvastatin pharmacokinetics were investigated in presence of Danshensu in rats. Then, the primary rat hepatocytes model was established to explore the effects of Danshensu on the uptake of rosuvastatin by hepatocytes. Finally, HEK293T cells with overexpression of OATP1B1*a and OATP1B1*5 were established using a lentiviral delivery system to explore the effects of Danshensu on the uptake of rosuvastatin. Rosuvastatin pharmacokinetic parameters of C(max0, AUCO(0-t), AUC(0-∞) were increased about 123%, 194% and 195%, by Danshensu in rats, while the CL z/F value was decreased by 60%. Uptake of rosuvastatin in the primary rat hepatocytes was decreased by 3.13%, 41.15% and 74.62%, respectively in the presence of 20, 40 and 80 µmol x L(-1) Danshensu. The IC50 parameters was (53.04 ± 2.43) µmol x L(-1). The inhibitory effect of Danshensu on OATP1B1 mediated transport of rosuvastatin was related to the OATP1B1 gene type. In OATP1B1*5-HEK293T mutant cells, transport of rosuvastatin were reduced by (39.11 ± 4.94)% and (63.61 ± 3.94)%, respectively, by Danshensu at 1 and 10 µmol x L(-1). While transport of rosuvastatin was reduced by (8.22 ± 2.40)% and (11.56 ± 3.04)% and in OATP1B1*1a cells, respectively. Danshensu significantly altered the pharmacokinetics of rosuvastatin in rats, which was related to competitive inhibition of transport by OATPJBI. Danshensu exhibited a significant activity in the inhibition of rosuvastatin transport by OATP1B1*5-HEK293T, but not by OATP1B1*1a, suggesting a dependence on OATP1B1 sequence.

[The cytotoxicity of indirubin derivative PHII-7 against human breast cancer MCF-7 cells and its mechanisms].

OBJECTIVE: To observe the cytotoxicity of indirubin derivative PHII-7 against human breast cancer MCF-7 cells and to study its primary mechanisms. METHODS: The proliferation of MCF-7 cells was detected using MTT colorimetry. Annexin V/PI double staining was applied to detect the apoptosis rate of MCF-7 cells. The distribution of cell cycles was detected using PI staining and flow cytometry (FCM). The levels of reactive oxygen species (ROS) in MCF-7 cells were detected by DCFH-DA staining. The mRNA and protein levels of c-fos were detected using RT-PCR and Westem blot analysis. RESULTS: PHII-7 at different concentrations inhibited the proliferation of MCF-7 cells in a concentration-dependent manner, with the inhibitory rate ranging from 43.13% to 90.90% (P < 0.05). The inhibition was strengthened along with increased concentrations. PHII-7 at different concentrations could induce the apoptosis of MCF-7 cells. The early apoptosis rate was 1.43% +/- 0.02%, 9.14% +/- 0.36%, and 45.79% +/- 8.46%, respectively with the action of 1.25, 2.50, and 5.00 micromol/L PHII-7, respectively, showing dose-dependent manner. FCM analysis found that the proportion of MCF-7 cells in the G0/G1 phase and the S phase decreased after treatment with PHII-7, and the ratio of MCF-7 cells in the G2/M phase obviously increased (P < 0.01). The intra-cellular ROS level was significantly elevated 2 h after pretreatment with PHII-7. The levels of the protooncogene c-fos mRNA and protein were down-regulated in a dose-dependent manner after action of PHII-7. CONCLUSIONS: PHII-7 exerted obvious in vitro cytotoxic effects on MCF-7 cells. Its mechanisms might be associated with arresting the cell cycle, regulating the redox equilibrium, and down-regulating the expression of the protooncogene.