The effect of TGF-beta-induced epithelial–mesenchymal transition on the expression of intracellular calcium-handling proteins in T47D and MCF-7 human breast cancer cells

The contribution of Ca2+ in TGF-β-induced EMT is poorly understood. We aimed to confirm the effect of TGF-β on the gene expression of intracellular calcium-handling proteins and to investigate the potential underlying mechanisms in TGF-β-induced EMT. T47D and MCF-7 cells were cultured in vitro and treated with TGF-β. The mRNA expression of EMT marker genes and intracellular calcium-handling proteins were quantified by qRT-PCR. qRT-PCR and Western blot analysis results verified the changes of EMT marker gene expression. Furthermore, we found that TGF-β induced cell morphological changes significantly with an increase of cell surface area and cell length. These results indicated that TGF-β induced EMT. The mRNA expression levels of SPCA1, SPCA2 and MCU were not influenced by TGF-β treatment, while NCX1 expression was decreased in T47D cells. In addition, the mRNA levels of SERCAs and IP3Rs were significantly changed due to TGF-β-induced EMT. The TGF-β-treated T47D cells exhibited markedly greater response to ATP than the control cells, and the descent velocity of cytosolic calcium concentration was faster in TGF-β-treated cells than in control cells. This is the first report to demonstrate that TGF-β-induced EMT in human breast cancer cells is associated with alterations in endoplasmic reticulum calcium homeostasis.