Effect of 1,25-dihydroxyvitamin D_3 and Tamoxifen on cell cycle distribution and apoptosis of MDA-MB-231 cells transfected with ER? expression vector containing vitamin D response element / 第三军医大学学报

ABSTRACT

Objective To study the effect of 1,25-dihydroxyvitamin D_(3) and Tamoxifen on cell cycle distribution and apoptosis of MDAMB-231 cells transfected with ER? expression vector containing vitamin D response element.Methods The 4 VDRE-Tk sequence of VDRE-pGL3 reporter vector was cloned into ER?/pcDNA3.1+ vector and then was transfected into MDA-MB-231 breast cancer cells.MDA-MB-231~(VDRE-ER?) breast cancer cells were treated with 1,25-dihydroxyvitamin D_(3) and Tamoxifen to observe their pro-apoptotic effect by TUNEL and to determine whether cell cycle progression could be repressed by FCM.Results As compared with control group,MDA-MB-231~(VDRE-ER?) cells at G_(0)/G_(1) phase increased profoundly after treated with 1,25-dihydroxyvitamin D_(3) and Tamoxifen for 72 h.Meanwhile,1,25-dihydroxyvitamin D_(3) and Tamoxifen synergistically induced the apoptosis of MDA-MB-231~(VDRE-ER?) cells.Conclusion Transfection of VDRE-Tk-ER? expression vector into ER?-negative breast cancer cells could effectively recover its responsiveness to Tamoxifen under the induction of 1,25-dihydroxyvitamin D_(3) by blocking the cell cycle progression and inducing apoptosis.