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Previous studies showed the effects of resveratrol (RES) on several cancer cells, including prostate cancer (PCa) cell apoptosis without taking into consideration the impact of the tumor microenvironment (TME). The TME is composed of cancer cells, endothelial cells, blood cells, and cancer-associated fibroblasts (CAF), the main source of growth factors. The latter cells might modify in the TME the impact of RES on tumor cells via secreted factors. Recent data clearly show the impact of CAF on cancer cells apoptosis resistance via secreted factors. However, the effects of RES on PCa CAF have not been studied so far. We have investigated here for the first time the effects of RES on the physiology of PCa CAF in the context of TME. Using a prostate cancer CAF cell line and primary cultures of CAF from prostate cancers, we show that RES activates the N-terminal mutated Transient Receptor Potential Ankyrin 1 (TRPA1) channel leading to an increase in intracellular calcium concentration and the expression and secretion of growth factors (HGF and VEGF) without inducing apoptosis in these cells. Interestingly, in the present work, we also show that when the prostate cancer cells were co-cultured with CAF, the RES-induced cancer cell apoptosis was reduced by 40%, an apoptosis reduction canceled in the presence of the TRPA1 channel inhibitors. The present work highlights CAF TRPA1 ion channels as a target for RES and the importance of the channel in the epithelial-stromal crosstalk in the TME leading to resistance to the RES-induced apoptosis.

Fourteen-day-old rat pituitary tissue represents an attractive model for studying cell population dynamics, particularly of gonadotrophs. Prolonged three-dimensional culture in serum- and hormone-free medium causes a striking decline in somatotroph abundance but a several-fold rise in monohormonal LH beta-positive cell number, whereas bihormonal gonadotrophs almost disappear. In the present study, we investigated whether these changes are inter-related by examining the effects of growth hormone-releasing hormone (GHRH) and glucocorticoids, two protagonist regulators of somatotrophs. Cells were identified by single cell reverse transcriptase-polymerase chain reaction (RT-PCR) and immunofluorescence. Supplementation of the cultures for 2 weeks with GHRH (1 nm) did not augment the proportion of somatotrophs, but expanded the nonhormonal cell population. GHRH reduced the proportion of monohormonal luteinising hormone (LH)beta mRNA positive cells to approximately 50% of control, although the effect was not seen when these cells were visualised by immunostaining. Supplementation of the cultures with dexamethasone (4 nM) for 3 weeks partially rescued LH beta/follicle-stimulating hormone beta cells and fully rescued the GH mRNA cells in parallel with a decline in nonhormonal cell abundance, but strongly reduced bromodeoxyuridine labelling of GH-immunoreactive cells. As studied by patch-clamp single cell RT-PCR at the start of culture, GHRH caused an acute rise in intracellular [Ca(2+)] in some monohormonal GH cells, but at a higher incidence in cells expressing LH beta mRNA, alone or in combination with GH mRNA and/or pro-opiomelanocortin (POMC) mRNA. The present data suggest that, in the 14-day-old rat pituitary, the majority of GHRH target cells are cells expressing LH beta mRNA alone or in combination with GH and/or POMC mRNA. The data show co-regulation of gonadotroph and somatotroph population sizes by glucocorticoids and GHRH, with the former preserving bihormonal gonadotrophs and the latter repressing LH beta-only cell abundance. GHRH may not expand the somatotroph population unless glucocorticoid hormone is present to maintain terminal differentiation.