title: High-throughput proteome analysis reveals targeted TRPM8 degradation in prostate cancer.
abstract: The Ca2+-permeable ion channel TRPM8 is a hallmark of the prostate epithelium. We recently discovered that TRPM8 is an ionotropic testosterone receptor. This finding suggested that testosterone-induced TRPM8 activity regulates Ca2+ homeostasis in the prostate epithelium. Since androgens are significantly implicated in prostate cancer development, the role of the novel testosterone receptor TRPM8 in cancer was assessed in our study. Although TRPM8 mRNA levels increase at the early prostate cancer stages, we found that it is not proportionally translated into TRPM8 protein levels. High-throughput proteome analysis revealed that TRPM8 degradation is enhanced in human prostate cancer cells. This degradation is executed via a dual degradation mechanism with the involvement of both lysosomal and proteasomal proteolytic pathways. The evaluation of the TRPM8 expression pattern in prostate cancer patients further confirmed the incidence of TRPM8 removal from the plasma membrane and its internalization pattern coincided with the severity of the tumor. Together, our results indicate that enhanced TRPM8 hydrolysis in prostate cancer could present an adaptation mechanism, sustained via bypassing testosterone-induced rapid Ca2+ uptake through TRPM8, thus, diminishing the rates of apoptosis. In this light, recovery of TRPM8 may pose a novel therapeutic strategy for an anti-tumor defense mechanism.
authors.affiliation: University of Illinois College of Medicine, Department of Cancer Biology and Pharmacology, Peoria, IL 61605, USA.
authors.forename: Swapna
authors.initials: S
authors.lastname: Asuthkar
authors.affiliation: University of Illinois College of Medicine, Department of Cancer Biology and Pharmacology, Peoria, IL 61605, USA.
authors.forename: Lusine
authors.initials: L
authors.lastname: Demirkhanyan
authors.affiliation: University of Illinois College of Medicine, Department of Cancer Biology and Pharmacology, Peoria, IL 61605, USA.
authors.forename: Samuel Robert
authors.initials: SR
authors.lastname: Mueting
authors.affiliation: Proteomics and Mass Spectrometry Core Facility, Life Sciences Research Institute, Dalhousie University, Halifax, NS B3H 4R2, Canada.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Cohen
authors.affiliation: University of Illinois College of Medicine, Department of Cancer Biology and Pharmacology, Peoria, IL 61605, USA.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Zakharian
mesh_terms: D045744:Cell Line, Tumor; D057166:High-Throughput Screening Assays; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D008297:Male; D013058:Mass Spectrometry; D011471:Prostatic Neoplasms / Q000378:metabolism*; D020543:Proteome / Q000378:metabolism; D040901:Proteomics; D050053:TRPM Cation Channels / Q000378:metabolism*
chemical_list: D020543:Proteome; D050053:TRPM Cation Channels; C425966:TRPM8 protein, human
keywords: androgens; prostate cancer; protein degradation; testosterone; transient receptor potential melastatin 8 channel (TRPM8)