Background: The transient receptor potential vanilloid 2 (TRPV2) channel is known to have strong species-dependent activation modes and divers functions. Based on previous results, which showed expression by human ovarian granulosa cells, w e studied human TRPV2 in human granulosa cell tumors (GCTs) and derived cells (KGN cells). GCTs are rare ovarian tumors, for which neither specific therapies, nor adequate markers are available. Methods: We analyzed primary GCTs, including a panel of 63 GCT samples, and KGN cells. We performed immunohisto-/cytochemistry, RT-PCR, Western blotting and measurements of intracellular Ca ²⁺ levels. We studied consequences of CRISPR/Cas9-based deletion of TRPV2 on cell proliferation, migration and macropinocytotic behavior, examined changes in steroid hormone production, and determined corresponding alterations of the proteome of these cells. Results: We found that GCTs express TRPV2 to a large percentage (95%). To examine roles of TRPV2, we turned to the human GCT-derived KGN cell line. CRISPR/Cas9-based deletion of TRPV2 resulted in larger cell size, increases in proliferation, migration and macropinocytotic behavior, changes in steroid production, and corresponding alterations of the proteome of these cells. Deletion of TRPV2 also significantly reduced susceptibility to cell death, which was induced within hours by cannabidiol (CBD), a preferred ligand of TRPV2, in a concentration- and time-dependent manner. However, cell death was not completely abolished and the analysis of the TRPV2-interactome suggested the voltage-dependent anion channel 1 (VDAC1) as a further target for CBD. VDAC1, as part of a cascade involving formation and persistent opening of the mitochondrial permeability transition pore (mPTP), is linked to cell death. A blocker of mPTP formation, cyclosporin A, significantly decreased the vulnerability of KGN cells to CBD-induced cell death. TRPV2-depleted KGN cells treated with cyclosporin A became almost completely insensitive to the effects of CBD. Conclusions: The results reveal a role of TRPV2 in GCT cells. Thus, CBD causes cell death in KGN cells via direct TRPV2 activation and via interaction with VDAC1. Expression of TRPV2 may thus be a novel marker to distinguish subtypes of GCTs. Furthermore, TRPV2 represents a novel drug target.

Background: Clonidine has been used in clinical medicine, e.g., to treat high blood pressure and other conditions. Animal studies have linked its use to impairments of male reproductive functions, and although only a few reports exist for the human species, such actions may exist in man as well. The underlying reasons and, specifically, possible actions of clonidine at the level of the testis are not known. Introduction: Clonidine is an agonist at the α_2A-adrenoceptor (ADRA2A), which, as data bank mining indicated, is expressed by several cells of the human testis. The human testis and most of its cells are, however, not readily accessible to experimental testing. Cells from the peritubular wall compartment (human testicular peritubular cells; HTPCs) are the exception. Methods and Results: As shown by immunohistochemical/immunocytochemical and PCR techniques these cells express ADRA2A and retain expression upon isolation and culture. When tested over a concentration range (1–1000 µM) and 24 h, clonidine did not visibly affect HTPC morphology but significantly stimulated IL6 mRNA levels in a concentration-dependent manner. ELISA measurements of cell culture supernatants confirmed a stimulatory action of clonidine (10 µM) on secreted IL6. When examined in collagen gel contraction assays of HTPCs, clonidine (10 µM) exerted a slight relaxing action, while a proteomic study revealed that clonidine (10 µM) did not significantly change cellular protein abundance of HTPCs after 24 h (data available via ProteomeXchange with identifier PXD052220). Conclusion: Thus, ADRA2A-bearing cells in the human testis are targets for catecholamines and drugs such as clonidine. The results of this HTPCs-focused study only show the tip of the iceberg. It is likely that catecholamines/catecholaminergic drugs have the potential to interfere with human testicular functions.