Abstract
Background Thermo-TRPs (temperature-sensitive transient receptor potential channels) belong to the TRP (transient receptor potential) channel superfamily. Emerging evidence implied that thermo-TRPs have been involved in regulation of cell fate in certain tumors. However, their distribution profiles and roles in melanoma remain incompletely understood. Methods Western blot and digital PCR approaches were performed to identify the distribution profiles of six thermo-TRPs. MTT assessment was employed to detect cell viability. Flow cytometry was applied to test cell cycle and apoptosis. Calcium imaging was used to determine the function of channels. Five cell lines, including one normal human primary epidermal melanocytes and two human malignant melanoma (A375, G361) and two human metastatic melanoma (A2058, SK-MEL-3) cell lines, were chosen for this research. Results In the present study, six thermo-TRPs including TRPV1/2/3/4, TRPA1, and TRPM8 were examined in human primary melanocytes and melanoma cells. We found that TRPV2/4, TRPA1, and TRPM8 exhibited ectopic distribution both in melanocytes and melanoma cells. Moreover, activation of TRPV2 and TRPV4 could lead to the decline of cell viability for melanoma A2058 and A375 cells. Subsequently, activation of TRPV2 by 2-APB (IC50 = 150 μM) induced cell necrosis in A2058 cells, while activation of TRPV4 by GSK1016790A (IC50 = 10 nM) enhanced apoptosis of A375 cells. Furthermore, TRPV4 mediated cell apoptosis of melanoma via phosphorylation of AKT and was involved in calcium regulation. Conclusion Overall, our studies revealed that TRPV4 and TRPV2 mediated melanoma cell death via channel activation and characterized the mechanism of functional TRPV4 ion channel in regulating AKT pathway driven antitumor process. Thus, they may serve as potential biomarkers for the prognosis and are targeted for the therapeutic use in human melanoma.
Highlights
Malignant melanoma is a very aggressive and lethal form of cutaneous cancer
All antibodies to six thermoTRPs were purchased from Pierce Biotechnology; other antibodies were obtained from Cell Signaling Technology (CST, anti-AKT, anti-pAKT, antiP38, anti-pP38, anti-JNK, anti-pJNK, anti-ErK1/2, and antipErK1/2)
The assessments clearly showed differential expression profiles of thermo-transient receptor potential channels (TRPs), in which TRPV1 was hardly detected in human melanocytes, and very weak expression was found in human melanoma cells (Figure 1(a)(i))
Summary
Malignant melanoma is a very aggressive and lethal form of cutaneous cancer. It usually derives from the transformation of melanocytes causing dysfunction to normal cellular growth. Emerging evidence implied that thermo-TRPs have been involved in regulation of cell fate in certain tumors Their distribution profiles and roles in melanoma remain incompletely understood. Six thermo-TRPs including TRPV1/2/3/4, TRPA1, and TRPM8 were examined in human primary melanocytes and melanoma cells. Our studies revealed that TRPV4 and TRPV2 mediated melanoma cell death via channel activation and characterized the mechanism of functional TRPV4 ion channel in regulating AKT pathway driven antitumor process. They may serve as potential biomarkers for the prognosis and are targeted for the therapeutic use in human melanoma
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