TRPM3 and miR-204 Establish a Regulatory Circuit that Controls Oncogenic Autophagy in Clear Cell Renal Cell Carcinoma

• TRPM3 promotes tumor growth in ccRCC
• TRPM3 is repressed by VHL through direct and indirect effects of miR-204
• TRPM3 is a positive regulator of oncogenic autophagy at multiple steps
• TRPM3 can be a target for experimental therapeutics

SummaryAutophagy promotes tumor growth by generating nutrients from the degradation of intracellular structures. Here we establish, using shRNAs, a dominant-negative mutant, and a pharmacologic inhibitor, mefenamic acid (MFA), that the Transient Receptor Potential Melastatin 3 (TRPM3) channel promotes the growth of clear cell renal cell carcinoma (ccRCC) and stimulates MAP1LC3A (LC3A) and MAP1LC3B (LC3B) autophagy. Increased expression of TRPM3 in RCC leads to Ca2+ influx, activation of CAMKK2, AMPK, and ULK1, and phagophore formation. In addition, TRPM3 Ca2+ and Zn2+ fluxes inhibit miR-214, which directly targets LC3A and LC3B. The von Hippel-Lindau tumor suppressor (VHL) represses TRPM3 directly through miR-204 and indirectly through another miR-204 target, Caveolin 1 (CAV1).

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