| Objective: Chemotherapy plays an important role in synthetic therapy of breast cancer. Because of multidrug resistance, the effect of chemotherapy is impacted, even the chemotherapy is fail, which could impact the prognosis of patients. For this reason, searching reversal agent for multidrug resistance to enhance the curative effect of chemotherapy is problem to be emergent settled in clinic. At present there are a lot of investigations concerned with retroconversion of MDR. The best studied mechanism involves P-gp(P-glycoprotein) mediated drug efflux. This study focuses on MDR reversal agents from medicinal plants, which can interfere with P-gp. Lobeline, a piperidine alkaloid from Lobelia inflata and several other Lobelia species. The purpose of this experiment is to investigate whether lobeline could reverse MDR like verapamil, and its reversal mechanism.Methods: We study the change of sensitivity of breast cancer cell line MCF-7/ADM to Chemistry drug under the intervention of lobeline. MTT assay was used to determine the cell growth inhibiting ratio of MCF-7/ADM and MCF-7/ADM intervened with lobeline by ADM and 5-Fu. Fluorospectorphotometer was used to determine intracellular concentration of rhodamine123 of untreated MCF-7/ADM cells and MCF-7/ADM intervened with lobeline 1μM, 5μM, 10μM, 20μM, 50μM and 100μM. Taking untreated MCF-7/ADM cells as control, we used Flow cytometry to determine intracellular concentration of rhodaminel23 of MCF-7/ADM intervened with lobeline 20μM, comparing with that of MCF-7/ADM intervened with verapamil 20μM. Statistical Analysis depends on SPSS 13.0.Results: 1,Intervened by lobeline 10μM, the sensitivity of MCF-7/ADM to ADM and 5-Fu was increased. Inhibitive concentration 50 of ADM decline from (44.81±0.43)μg/ml to (16.72±0.75)μg/ml, reversion index is 2.68; Inhibitive concentration 50 of 5-Fu decline from (53.12±1.60)μg/mlto(38.90±1.43)μg/ml, reversion index is 1.37. 2,Fluorescence intensity is significantly higher than control when lobeline concentration is more than 10μM. 3,The reversal efficacy of 20uM lobeline is 71.6% of that of 20μM verapamil.Conclusions: Lobeline could reverse the multidrug-resistance of MCF-7/ADM cell line, and its reversal mechanism might be inhibiting the expression of P-glycoprotein.
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