The Experimental Study On Orai1 And Orai3 Expression Of Human Breast Cancer Cells Treated By 1,25 Dihydroxy Vitamin D3

?Objective?To invesgated the changes in expression of m RNA and protein levels of cellular Ca2+ channel components Orai1,Orai3 in MCF-7(ER+,VDR+)? MDA-MB-231(ER-,VDR-)?MDA-MB-453(ER-,VDR+)human breast cancer cells lines treated respectively by appropriate concentrations of 1,25-dihydroxyvitamin D3(a active form of vitamin D, 1,25-(OH)2D3), analyse the effects of 1,25-(OH) 2D3 on expression of Orai in human breast cancer cells,and explore the relationship between molecular pathway of Orai-mediated Ca2+signals induced by1,25-(OH) 2D3 and the estrogen receptor pathway in breast cancer, and the potential Ca2+ signal mechanism of promoting apoptosis of 1,25-(OH) 2D3 in human breast cancer cells which have different expression status of ER and VDR.?Methods?The human breast cancer cells MCF-7(ER+/VDR+), MDA-MB-231(ER-/VDR-)and MDA-MB-453(ER-/VDR+)in the logarithmic growth phasewere treated respectivelywith1,25-(OH)2D3(1×10-8mol/L). 17-?-estradiol(1×10-9mol/L) and tamoxifen(1×10-6mol/L)were used to treated the three kinds of breast caner cells as control groups.Cells were collected at the point of 48 h after treatment above, the m RNA expression levels of Orai1 and Orai3 were detected by Real-time RT-PCR and the protein expressionwere detected by Western Blot.?Results?1.The expression level of Orai3 in ER-positivebreast cancer cell MCF-7 was higher than ER-negtive cells MDA-MB-231 and MDA-MB-453(P< 0.05); 17-?-estradiol increased the expression of Orai3 in ER-positivebreast cancer cellMCF-7,and the ER inhibitor tamoxifen had the opposite effect(P< 0.05).2. 1,25-(OH) 2D3 could also down-regulate the expression of Orai3 in ER-positive cell MCF-7(P<0.05),this difference had't seen in ER-negtive cells MDA-MB-231 and MDA-MB-453(P>0.05).3.In contrast,1,25-(OH) 2D3 up-regulated the expression of Orai1 but not Orai3 in VDR-negtive cell MDA-MB-231(P < 0.05),but not in VDR-positve cells MCF-7 and MDA-MB-453( P>0.05).?Conclusions?1.The Orai3 expression levels were elevated in ER-positive cell MCF-7 compare to the ER-negtive cells MDA-MB-231 and MDA-MB-453,and might be regulated by estrogen receptor pathway.2.The changes in expression of cellular Orai3 induced by vitamin D hormone through mechanism of VDR pathway may have intersection with estrogen receptor pathway.3.In VDR-negtive cell MDA-MB-231,besides the VDR and ER pathway,the vitamin D hormone may have other mechanism to impact the intracellular Orai1-mediated Ca2+ signal and the downstream Ca2+-dependent targets.