Human TRPC6 blocking peptide

Stimulation of Ca2+ permeable TRPM3 (transient receptor potential melastatin-3) channels with the steroid ligand pregnenolone sulfate activates stimulus-responsive transcription factors, including the transcription factor AP-1 (activator protein-1). As part of a search for AP-1-regulated target genes we analyzed the gene encoding interleukin-8 (IL-8) in HEK293 cells expressing TRPM3 channels. Here, we show that stimulation of TRPM3 channels activated transcription of an IL-8 promoter-controlled reporter gene that was embedded into the chromatin of the cells. Mutational analysis of the IL-8 promoter revealed that the AP-1 binding site of the IL-8 promoter was essential to connect TRPM3 stimulation with the transcription of the IL-8 gene. Genetic experiments revealed that the basic region leucine zipper proteins c-Jun and ATF2 and the ternary complex factor Elk-1 are essential to couple TRPM3 channel stimulation with the IL-8 gene. Moreover, we identified extracellular signal-regulated protein kinase (ERK1/2) as signal transducer connecting TRPM3 stimulation with enhanced transcription of the IL-8 gene. Furthermore, we show that stimulation of TRPC6 (transient receptor potential canonical-6) channels with its ligand hyperforin also increased 1L-8 promoter activity, involving the AP-1 binding site within the IL-8 gene, suggesting that activation of IL-8 gene transcription may be a common theme following TRP channel stimulation.

Active surveillance has emerged as an alternative to immediate treatment for men with low-risk prostate cancer. Accordingly, identification of environmental factors that facilitate progression to more aggressive stages is critical for disease prevention. Although calcium-enriched diets have been speculated to increase prostate cancer risk, their impact on early-stage tumors remains unexplored. In this study, we addressed this issue with a large interventional animal study. Mouse models of fully penetrant and slowly evolving prostate tumorigenesis showed that a high calcium diet dramatically accelerated the progression of prostate intraepithelial neoplasia, by promoting cell proliferation, micro-invasion, tissue inflammation, and expression of acknowledged prostate cancer markers. Strikingly, dietary vitamin D prevented these calcium-triggered tumorigenic effects. Expression profiling and in vitro mechanistic studies showed that stimulation of PC-3 cells with extracellular Ca2+ resulted in an increase in cell proliferation rate, store-operated calcium entry (SOCE) amplitude, cationic channel TRPC6, and calcium sensing receptor (CaSR) expression. Notably, administration of the active vitamin D metabolite calcitriol reversed all these effects. Silencing CaSR or TRPC6 expression in calcium-stimulated PC3 cells decreased cell proliferation and SOCE. Overall, our results demonstrate the protective effects of vitamin D supplementation in blocking the progression of early-stage prostate lesions induced by a calcium-rich diet. (C) 2016 AACR.