Transient Receptor Potential Vanilloid 1 Expression and Functionality in MCF-7 Cells: A Preliminary Investigation

Abstract

PurposeTransient receptor potential vanilloid 1 (TRPV1) is a nonselective cation channel belonging to the transient receptor potential family, and it is expressed in different neoplastic tissues. Its activation is associated with regulation of cancer growth and progression. The aim of this research was to study the expression and pharmacological characteristics of TRPV1 in cells derived from human breast cancer MCF-7 cells.MethodsTRPV1 presence was assessed by binding studies and Western blotting. Receptor binding characteristics were evaluated through competition assays, while 3-(4,5-dimethylthiazol-2-yl)-2,5,-dipheyltetrazolium bromide reduction assays were performed to confirm an early hypothesis regarding the modulation of cancer cell proliferation. The functionality of TRPV1 was evaluated by measuring Ca2+ uptake in the presence of increasing concentrations of TRPV1 agonists and antagonists.ResultsBinding studies identified a single class of TRPV1 (Bmax 1,492±192 fmol/mg protein), and Western blot showed a signal at 100 kDa corresponding to the molecular weight of human TRPV1. Among the different tested agonists and antagonists, anandamide (Ki: 2.8×10-11 M) and 5-iodoresiniferatoxin (5-I-RTX) (Ki: 5.6×10-11 M) showed the highest degrees of affinity for TRPV1, respectively. All tested TRPV1 agonists and antagonists caused a significant (p<0.05) decrease in cell growth rate in MCF-7 cells. For agonists and antagonists, the efficacy of tested compounds displayed the following rank order: resiniferatoxin>anandamide>capsaicin and 5-I-RTX=capsazepine, respectively.ConclusionThese data indicate that both TRPV1 agonists and antagonists induce significant inhibition of MCF-7 cell growth. Even though the mechanisms involved in the antiproliferative effects of TRPV1 agonists and antagonists should be further investigated, it has been suggested that agonists cause desensitization of the receptor, leading to alteration in Ca2+-influx regulation. By contrast, antagonists cause a functional block of the receptor with consequent fatal dysregulation of cell homeostasis.

Expression and functionality of TRPV1 in breast cancer cells

“…In our experiments, a significant reduction in cell proliferation after capsaicin stimulation was observed, diminished by the coapplication of capsazepin. This finding was in accordance with the results of Vercelli et al,43 who demonstrated a significant decrease in the cell growth rate of MCF-7 breast cancer cells upon capsaicin stimulation. Interestingly, Zheng et al44 furthermore showed that capsaicin was capable of enhancing the antineoplastic effects of pirarubicin, which is an analog of the antibiotic doxorubicin 45.…”

“…After we proved the existence and functionality of TRPV1, we conducted proliferation and migration analyses to investigate the long-term effects of capsaicin on SUM149PT cells. In a study by Sanchez et al,43 the role of TRPV1 in prostate cancer cell proliferation was analyzed. In our experiments, a significant reduction in cell proliferation after capsaicin stimulation was observed, diminished by the coapplication of capsazepin.…”

Endogenous TRPV1 stimulation leads to the activation of the inositol phospholipid pathway necessary for sustained Ca2+ oscillations

“…Virtually all pharmacological and molecular methods used to examine the function of these channels resulted in a decrease of cell viability. These methods included molecular up-or downregulation of the channels and activation or inhibition of channels with natural exogenous agonists or synthetic antagonists [16,17]. The activation of these channels leads to an increase in c cyt in breast and prostate cell lines, but the previously published studies presented only the average of evoked Ca 2+ cytoplasmic signals within the entire cell populations [17][18][19].…”

“…These methods included molecular up-or downregulation of the channels and activation or inhibition of channels with natural exogenous agonists or synthetic antagonists [16,17]. The activation of these channels leads to an increase in c cyt in breast and prostate cell lines, but the previously published studies presented only the average of evoked Ca 2+ cytoplasmic signals within the entire cell populations [17][18][19]. This method blurs the spatiotemporal character of individual intracellular Ca 2+ signals, which is essential to understand how TRPV1-mediated stimuli influence the cell behavior at the single cell level.…”

Transient Receptor Potential Vanilloid 1 in animal tissues: An overview to highlight similarities and differences with human species

“…These results found a confirmation in other studies that demonstrated that capsaicin could inhibit human cancer hormone-resistant cells and can provide chemopreventive effects [58] . Moreover, other studies demonstrated that capsaicin can mediate cell death of T24 (human bladder cancer), A172 (human glioma) [59; 60] , and MCF-7 [61] cell lines, nevertheless the use of TRPV1 ligands in cancer treatment should always be careful, as explained previously.…”