Reversal of multidrug resistance in drug-resistant human breast cancer cell line MCF-7/ADR by calmodulin antagonist O-(4-ethoxyl-butyl)-berbamine / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the reversal effect of O-(4-ethoxyl-butyl)-berbamine (EBB) on multidrug resistance (MDR) in MCF-7/ADR cell.</p><p><b>METHODS</b>3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to assess the antitumor effect of EBB and determine the reversal effects of different concentrations ( < or = IC20) of EBB on MCF-7/ADR cell. Flow cytometry was applied to observe the intracellular accumulation of Rh123 and cell cycle in the presence of EBB. The expressions of MDR-related genes mdr 1 and topoisomerase II b (top II b) were evaluated by reverse transcription-polymerase chain reaction.</p><p><b>RESULTS</b>The sensitivity of MCF-7/ADR to adriamycin (ADR) was enhanced up to 50. 40, 89.80, and 14.88 folds after exposure of the cells to 3 micromol/L EBB, 7.5 micromol/L EBB, and 10 micromol/L verapamil (VPL), respectively. After 2 hours of incubation with 6 micromol/L EBB, intracellular Rh123 accumulation in MCF-7/ADR cells was increased to the level comparable to that in MCF-7 cells. When 6 micromol/L EBB was added together with 2 micromol/L ADR, MCF-7/ ADR cells showed to be arrested in the G2/M phase. The declination of mdr 1 gene expression was observed when 6 micromol/L EBB, 12 micromol/L EBB, and 10 micromol/L VPL were added for 48 hours; meanwhile, the expression of top II b mRNA showed no significant change.</p><p><b>CONCLUSION</b>EBB has a strong reversal effect on MDR in MCF-7/ ADR cell, which may be achieved by enhancing the arrestment of MCF-7/ADR cells at G2/M phase and increasing intracellular drug concentration.</p>

Effect of calmodulin antagonist EBB on invasion of human fibrosarcoma cell HT1080 / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the potential effect of EBB, a calmodulin antagonist, on invasion of human fibrosarcoma cells HT1080.</p><p><b>METHODS</b>The antitumor effect of EBB was assessed by 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Activities of matrix metalloproteinase (MMP)-2 and MMP-9 were measured by Zymogrophy analysis. The mRNA levels, of MMP-2, MMP-9, and tissue inhibitor of metalloproteinases (TIMP)-1 were evaluated by reverse transcriptionpolymerase chain reaction (RT-PCR). Transwell chamber assay was applied to measure the effect of EBB on the invasion of HT1080 cells.</p><p><b>RESULTS</b>Calmodulin antagonist EBB inhibited the proliferation of HT1080 cells with an IC50 of (8.2 +/- 1.2) microg/ml. EBB down-regulated the activities of MMP-2 and MMP-9, and down-regulated the mRNA levels of MMP-2 and MMP-9, while up-regulated the mRNA levels of TIMP-1. The invasive ability of HT1080 cells was decreased to (31.13 +/- 2.265)%, (59.91 +/- 2.566)%, and (71.58 +/- 0.5960)% after exposure of the cells with 2, 5, and 10 microg/ml EBB, respectively.</p><p><b>CONCLUSION</b>Treatment with calmodulin antagonist EBB is effective in suppressing tumor invasion. The possible mechanism is the down-regulation of MMPs.</p>