Calcitriol Induces Endoplasmic Reticulum Stress Response in Breast Cancer Cells

Effects of calcitriol on expressions of ER stress related genes were evaluated with microarray. Calcitriol, the active form of vitamin D, is known to induce apoptosis in cancer cells and increase intracellular calcium. Increase in cytopalsmic calcicium levels may indicate a decrease in endoplasmic reticulum (ER) calcium levels since ER is the main storage unit for calcium. Decrease in ER calcium levels are known to induce ER stress which can lead to apoptosis. However the effects of calcitriol on ER stress have not been reported before. Here we hypotesized that the cellular effects of calcitriol can be explained by induction of ER stress. We have tested this hypothesis by assessing calcitriol induced transcriptomic alterations with a focus on ER stress related genes. We analyzed MCF-7 and MDA-MB-231 cells treated with calcitriol or DMSO (Each group consists of 3 replicates) using the Affymetrix Human Exon 1.0 ST platform. Array data was processed by Partek Genomic Suite. No technical replicates were performed.