Estrogen regulation of TRPM8 expression in breast cancer cells

Abstract

BackgroundThe calcium-permeable cation channel TRPM8 (melastatin-related transient receptor potential member 8) is over-expressed in several cancers. The present study aimed at investigating the expression, function and potential regulation of TRPM8 channels by ER alpha (estrogen receptor alpha) in breast cancer.MethodsRT-PCR, Western blot, immuno-histochemical, and siRNA techniques were used to investigate TRPM8 expression, its regulation by estrogen receptors, and its expression in breast tissue. To investigate the channel activity in MCF-7 cells, we used the whole cell patch clamp and the calcium imaging techniques.ResultsTRPM8 channels are expressed at both mRNA and protein levels in the breast cancer cell line MCF-7. Bath application of the potent TRPM8 agonist Icilin (20 μM) induced a strong outwardly rectifying current at depolarizing potentials, which is associated with an elevation of cytosolic calcium concentration, consistent with established TRPM8 channel properties. RT-PCR experiments revealed a decrease in TRPM8 mRNA expression following steroid deprivation for 48 and 72 hours. In steroid deprived medium, addition of 17-beta-estradiol (E2, 10 nM) increased both TRPM8 mRNA expression and the number of cells which respond to Icilin, but failed to affect the Ca2+ entry amplitude. Moreover, silencing ERα mRNA expression with small interfering RNA reduced the expression of TRPM8. Immuno-histochemical examination of the expression of TRPM8 channels in human breast tissues revealed an over-expression of TRPM8 in breast adenocarcinomas, which is correlated with estrogen receptor positive (ER+) status of the tumours.ConclusionTaken together, these results show that TRPM8 channels are expressed and functional in breast cancer and that their expression is regulated by ER alpha.

High Expression of Transient Receptor Potential Channels in Human Breast Cancer Epithelial Cells and Tissues: Correlation with Pathological Parameters

“…Recently, we also reported the expression and regulation of TRPM8 by estrogens in MCF-7 cells [31]. Two other studies have already shown the expression of TRPC4, TRPC6 and TRPV6 in T47D cells [26] as well as TRPC3 and TRPC6 in MCF-7 and MDA-MB-231 cell lines [32].…”

“…We have previously demonstrated that TRPC6 and TRPM7 are overexpressed in hBDA at both protein and mRNA levels, and their functional expression was recorded in the MCF-7 cancer cell line and human breast cancer epithelial (hBCE) cells isolated from surgical resection [29,30]. We also reported that TRPM8 expression is regulated by estrogens in breast cancer cells and tissues [31]. Other groups demonstrated that TRPC6 and TRPV6 expression increased in both breast cancer tissues and cell lines, and that both TRPC6 and TRPV6 regulated cell proliferation [26,32].…”

“…The sections were incubated with anti-TRPC6 or -TRPM7 antibody (Chemicon, 1/300), anti-TRPC1 or -TRPV6 antibody (Santa Cruz, 1/200 and 1/400) or anti-TRPM8 antibody (Abcam, 1/1500). Negative controls were performed by omitting the primary antibodies, and the specificity of these antibodies was reported in previous studies [29][30][31][34][35][36][37].…”

Over-expression of TRPM8 is associated with poor prognosis in urothelial carcinoma of bladder

“…In the subfamilies of TRP channels, TRP channel melastatin 8 (TRPM8) was identified and has been proposed to be the predominant thermoreceptor for cellular and behavioral responses to cold stimuli [7]. Although the aberrant expression of TRPM8 is detected in many tumors [8][9][10][11] and is represented as a key protein in central mechanisms of carcinogenesis, some disagreement of their roles in it was raised in different studies [12].…”

Regulation of TRP channels by steroids: Implications in physiology and diseases

“…Estrogen in particular has also been shown to induce the expression of TRPV1 channel in rats (Yan et al, 2007). In MCF-7 which is a breast cancer cell line, ERa has been shown to regulate the expression of TRPM8 (Chodon et al, 2010).…”