Katalin Rozmer

Transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) have been implicated in cancer biology, but their functional relevance in prostate adenocarcinoma (PAC) remains unclear. Therefore, we characterized TRPA1/TRPV1 expression and function in benign prostatic hyperplasia (BPH), PAC tissues, and PAC cell lines with different characteristics and examined the effects of their agonists on cancer-cell viability. TRPA1 and TRPV1 transcripts were assessed by RNAscope in situ hybridization and RT-qPCR, channel activity by Fura-2-based Ca²⁺ imaging, and viability/proliferation by ATP-based luminescence and automated cell counting. TRPA1 and/or TRPV1 mRNAs were detected in PAC tissues and cell lines, but selective stimulation with allyl-isothiocyanate (AITC) or capsaicin did not evoke Ca²⁺ influx, indicating no detectable functional channel activity under our experimental conditions. Non-selective TRPA1 activators induced Ca²⁺ influx responses that were not inhibited by the receptor antagonist A-967079. AITC concentration dependently reduced viability and proliferation of the androgen-sensitive 22Rv1 and LNCaP cells, and these effects were not prevented by TRPA1 antagonists. Capsaicin had no effect at TRPV1-selective concentrations. Thus, transcript expression does not predict functional TRPA1/TRPV1 activity in PAC cells, and AITC reduces PAC-cell viability through TRPA1-independent mechanisms.

Osteosarcoma is a highly malignant, painful cancer with poor treatment opportunities and a bad prognosis. Transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) receptors are non-selective cation channels that have been of great interest in cancer, as their expression is increased in some malignancies. In our study we aim to characterize the expression and functionality of the TRPA1 and TRPV1 channels in human and mouse osteosarcoma tissues and in a mouse cell line. TRPA1/Trpa1 and TRPV1/Trpv1 mRNA expressions were demonstrated by PCR gel electrophoresis and RNAscope in situ hybridization. The function of these channels was confirmed by their radioactive ₄₅Ca²⁺ uptake in response to the TRPA1 agonist, Allyl-isothiocyanate (AITC), and TRPV1 agonist, capsaicin, in K7M2 cells. An ATP-based K2M7 cell viability luminescence assay was used to determine cell viability after AITC or capsaicin treatments. Both TRPA1/Trpa1 and TRPV1/Trpv1 were expressed similarly in human and mouse osteosarcoma tissues, while Trpa1 transcripts were more abundantly present in K7M2 cells. TRPA1 activation with 200 µM AITC induced a significant ₄₅Ca²⁺ influx into K7M2 cells, and the antagonist attenuated this effect. In accordance with the lower Trpv1 expression, capsaicin induced a moderate ₄₅Ca²⁺ uptake, which did not reach the level of statistical significance. Both AITC and capsaicin significantly reduced K7M2 cell viability, demonstrating EC₅₀ values of 22 µM and 74 µM. The viability-decreasing effect of AITC was significantly but only partially antagonized by HC-030031, but the action of capsaicin was not affected by the TRPV1 antagonist capsazepine. We provide here the first data on the functional expression of the TRPA1 and TRPV1 ion channels in osteosarcoma, suggesting novel diagnostic and/or therapeutic perspectives.