Olfactory receptor OR51E2, also known as a Prostate Specific G-Protein Receptor, is highly expressed in prostate cancer but its function is not well understood. Through in silico and in vitro analyses, we identified 24 agonists and 1 antagonist for this receptor. We detected that agonist 19hydroxyandrostenedione, a product of the aromatase reaction, is endogenously produced upon receptor activation. We characterized the effects of receptor activation on metabolism using a prostate cancer cell line and demonstrated decreased intracellular anabolic signals and cell viability, induction of cell cycle arrest, and increased expression of neuronal markers. Furthermore, upregulation of neuron-specific enolase by agonist treatment was abolished in OR51E2-KO cells. The results of our study suggest that OR51E2 activation results in neuroendocrine trans-differentiation.These findings reveal a new role for OR51E2 and establish this G-protein coupled receptor as a novel therapeutic target in the treatment of prostate cancer.
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Significance:Prostate cancer is the second most common cancer in men. Most deaths from prostate cancer are due to the progression of localized disease into metastatic, castration-resistant prostate cancer characterized by increased number of neuroendocrine-like cells. These neuroendocrine-like cells are non-proliferating, terminally differentiated cells. Olfactory receptor OR51E2, also known as a Prostate Specific G-Protein Receptor, is highly expressed in prostate cancer, and its expression correlates with disease progression. Here, we identify and validate novel endogenous ligands for this receptor.We show that activation of OR51E2 by newly-discovered prostate cancer-relevant agonists facilitates cellular transformation, resulting in neuroendocrine trans-differentiation, a characteristic phenotype of castrate resistant prostate cancer. Our results establish this G-protein coupled receptor as a novel and therapeutic target for castration-resistant prostate cancer.
Highlights:• Discovery of novel agonists for olfactory receptor OR51E2/PSGR highly relevant to prostate cancer pathology• Activation of OR51E2 receptor by agonist N-acetyl-N-formyl-5-methoxykynurenamine (AFMK) results in release of 19-hydroxyandrostenedione (19-OH AD) from the prostate cancer cells indicating its endogenous production • Activation of OR51E2 receptor by 19-OH AD, AFMK, and propionic acid decreases anabolic and proliferative signals 3 • Activation of OR51E2 receptor by 19-OH AD and AFMK increases markers specific for neuroendocrine trans-differentiation (NEtD)• Ablation of the OR51E2 gene in prostate cancer cells treated with agonist 19-OH AD significantly reduces neuron-specific enolase INTRODUCTION G-protein coupled receptors (GPCRs) have emerged as important factors in tumor growth and metastasis 1-3 . Several GPCRs, such as the 5HT1c serotonin receptor 4 , the M1, M3, and M5 muscarinic receptors 5 , and the α1B-ADR adrenergic receptor 6 , can function as oncogenes when persistently activated. These GPCRs, which are normally...