Transient Receptor Potential Melastatin 8 (TRPM8) Channel Regulates Proliferation and Migration of Breast Cancer Cells by Activating the AMPK-ULK1 Pathway to Enhance Basal Autophagy.

Yuan Huang,Xing-Zhen Chen,Weiwei Zhao,Rui Zhang,Shi Li,Jingfeng Tang,Declan William Ali,Marek Michalak,Zhenhua Jia,Cefan Zhou

doi:10.3389/fonc.2020.573127

Abstract

The calcium-permeable cation channel TRPM8 (transient receptor potential melastatin 8) is a member of the TRP superfamily of cation channels that is upregulated in various types of cancer with high levels of autophagy, including prostate, pancreatic, breast, lung, and colon cancers. Autophagy is closely regulated by AMP-activated protein kinase (AMPK) and plays an important role in tumor growth by generating nutrients through degradation of intracellular structures. Additionally, AMPK activity is regulated by intracellular Ca2+ concentration. Considering that TRPM8 is a non-selective Ca2+-permeable cation channel and plays a key role in calcium homoeostasis, we hypothesized that TRPM8 may control AMPK activity thus modulating cellular autophagy to regulate the proliferation and migration of breast cancer cells. In this study, overexpression of TRPM8 enhanced the level of basal autophagy, whereas TRPM8 knockdown reduced the level of basal autophagy in several types of mammalian cancer cells. Moreover, the activity of the TRPM8 channel modulated the level of basal autophagy. The mechanism of regulation of autophagy by TRPM8 involves autophagy-associated signaling pathways for activation of AMPK and ULK1 and phagophore formation. Impaired AMPK abolished TRPM8-dependent regulation of autophagy. TRPM8 interacts with AMPK in a protein complex, and cytoplasmic C-terminus of TRPM8 mediates the TRPM8–AMPK interaction. Finally, basal autophagy mediates the regulatory effects of TRPM8 on the proliferation and migration of breast cancer cells. Thus, this study identifies TRPM8 as a novel regulator of basal autophagy in cancer cells acting by interacting with AMPK, which in turn activates AMPK to activate ULK1 in a coordinated cascade of TRPM8-mediated breast cancer progression.

Highlights

The transient receptor potential melastatin 8 (TRPM8), a member of the TRP family, is a thermally regulated nonselective Ca2+-permeable cation channel
An increase in the intracellular Ca2+ concentration leads to activation of calcium/ calmodulin-dependent protein kinase kinase b (CaMKKb), which is the upstream regulator of AMPK activity that increases phosphorylation of AMPK [16, 17]
Previous studies demonstrated that cytosolic Ca2+ is an important regulator of autophagy [16, 17]; it is not known whether TRPM8 is involved in the regulation of basal autophagy

Summary

Introduction

The transient receptor potential melastatin 8 (TRPM8), a member of the TRP family, is a thermally regulated nonselective Ca2+-permeable cation channel. Increasing evidence indicates that basal autophagy plays the critical roles in the development of local recurrence after therapy failure in human cancer [7,8,9]. AMP-activated protein kinase (AMPK) detects the cellular metabolic status and is considered the key regulator of basal autophagy. AMPK regulates the activity of mammalian target of rapamycin (mTOR) to control the level of autophagy. An increase in the phosphorylated form of AMPK (pAMPK) inhibits mTOR activity and leads to activation of autophagy. An increase in the intracellular Ca2+ concentration leads to activation of calcium/ calmodulin-dependent protein kinase kinase b (CaMKKb), which is the upstream regulator of AMPK activity that increases phosphorylation of AMPK [16, 17]. Intracellular Ca2+ concentration is an important regulator of autophagy

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