Deviation of the ambient temperature is one of the most ubiquitous stimuli that continuously affect mammals' skin. Although the role of the warmth receptors in epidermal homeostasis (EH) was elucidated in recent years, the mystery of the keratinocyte mild-cold sensor remains unsolved. Here we report the cloning and characterization of a new functional epidermal isoform of the transient receptor potential M8 (TRPM8) mild-cold receptor, dubbed epidermal TRPM8 (eTRPM8), which is localized in the keratinocyte endoplasmic reticulum membrane and controls mitochondrial Ca 2+ concentration ([Ca 2+ ] m ). In turn, [Ca 2+ ] m modulates ATP and superoxide (O •−2 ) synthesis in a cold-dependent manner. We report that this fine tuning of ATP and O •−2 levels by cooling controls the balance between keratinocyte proliferation and differentiation. Finally, to ascertain eTRPM8's role in EH in vivo we developed a new functional knockout mouse strain by deleting the pore domain of TRPM8 and demonstrated that eTRPM8 knockout impairs adaptation of the epidermis to low temperatures.he skin epidermis provides a protective barrier that guards the body against an uncongenial environment. Under the influence of a variety of ambient factors the skin epidermis undergoes continuous regeneration through so-called epidermal homeostasis (EH): the fine-tuning of the balance between proliferation, directional migration, differentiation, and death of keratinocytes. EH involves complex molecular and chemical pathways, regulating dynamic and continuous transition of keratinocytes from the proliferating state in the basal layer to the nonproliferating state in the suprabasal layer before the beginning of the differentiation in the stratum spinosum and stratum granulosum. The terminal differentiation step, characterized by keratinocyte death, transforms keratinocytes into corneocytes, which form the waterproof, mechanically resistant sheath of the stratum corneum (1).Deviation of the ambient temperature is one of the most important stimuli that constantly affect mammals' skin. At ambient temperatures from +10°C to +30°C, the unprotected human skin temperature settles at mean steady-state values within the range of +24°C to +33°C, respectively (2). Temperature is perceived by thermoreceptors, the ion channels that belong to the transient receptor potential (TRP) superfamily (for review see ref.3). Of these, TRPV1 and TRPV2 are activated by heat (above 42°C and above 52°C, respectively) (4), whereas TRPM8 and likely TRPA1 are activated by mild (5, 6) and noxious (7-9) cold, respectively. Heatstimulated keratinocytes have been shown to secrete ATP (10) and, taking into account that purinergic receptors are expressed in keratinocytes (11), TRPV3 is involved in a paracrine heat-

In prostate carcinogenesis, androgens are known to control the expression of the transient receptor potential melastatin 8 (TRPM8) protein via activation of androgen receptor (AR). Overexpression and/or activity of TRPM8 channel was shown to suppress prostate cancer (PCa) cell migration. Here we report that at certain concentrations androgens facilitate PCa cell migration. We show that underlying mechanism is inhibition of TRPM8 by activated AR which interacts with the channel within lipid rafts microdomains of the plasma membrane. Thus, our study has identified an additional nongenomic mechanism of the TRPM8 channel regulation by androgens that should be taken into account upon the development of novel therapeutic strategies.

Triple-negative breast cancers (TNBC) represent the most aggressive form of breast cancers and their treatment are challenging due to the tumor heterogeneity. The high death rate and the limited systemic treatment options for TNBC necessitate the search for alternative chemotherapeutics. We previously found that FcOHTAM, an organometallic derivative of hydroxytamoxifen, showed in vitro a strong antiproliferative effect on various breast cancer cell lines, including MDA-MB-231 cells, the archetype of TNBC. In this study, we developed stealth FcOHTAM loaded lipid nanocapsules (LNCs) to further evaluate this novel drug on a TNBC xenografted model. Cell cycle analysis of MDA-MB-231 cells confirmed the preservation of the drug activity through LNCs causing a cycle arrest in phase S after 48 h exposure at the IC50 concentration (2 μm). Two intraperitoneal injections of FcOHTAM loaded LNCs (20 mg/kg) administered to luciferase-transfected MDA-MB-231 tumors bearing mice led to a marked delay in tumor growth. As a consequence, a significantly lower tumor volume was obtained at the end of the experiment with a difference of 36% at day 38 compared to the untreated group. These results represent the first evidence of an in vivo effect of FcOHTAM and ferrocenyl derivatives in general on xenografted breast tumors.

Since its cloning a decade ago, TRPM8 channel has emerged as a promising prognostic marker and a putative therapeutic target in prostate cancer (PCa). However, recent studies have brought to light the complexity of TRPM8 isoforms in PCa. Consequently, the respective role of each TRPM8 isoform needs to be deciphered prior to considering TRPM8 as an attractive therapeutic target. Full-length (6 transmembrane (TM)-domain) TRPM8 channel is overexpressed in early PCa and repressed in advanced prostate tumors whereas the localization of the truncated, 4TM-TRPM8 channel (4 transmembrane (TM)-domain), in the membranes of endoplasmic reticulum (ER) is independent of the pathogenic status of epithelial cells. In the same line, expression of non-channel cytoplasmic small TRPM8 isoforms (namely sM8) is conserved in cancer cells. In this study, we identify sM8s as putative regulator of PCa cell death. Indeed, suppression of sM8 isoforms was found to induce concomitantly ER stress, oxidative stress, p21 expression and apoptosis in human epithelial prostate cancer cells. We furthermore demonstrate that induction of such mechanisms required the activity of 4TM-TRPM8 channels at the ER-mitochondria junction. Our study thus suggests that targeting sM8 could be an appropriate strategy to fight prostate cancer.

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.

Cellular senescence is implicated in a great number of diseases including cancer. Although alterations in mitochondrial metabolism were reported as senescence drivers, the underlying mechanisms remain elusive. We report the mechanism altering mitochondrial function and OXPHOS in stress-induced senescent fibroblasts. We demonstrate that TRPC3 protein, acting as a controller of mitochondrial Ca2+ load via negative regulation of IP3 receptor-mediated Ca2+ release, is down regulated in senescence regardless of the type of senescence inducer. This remodelling promotes cytosolic/mitochondrial Ca2+ oscillations and elevates mitochondrial Ca2+ load, mitochondrial oxygen consumption rate and oxidative phosphorylation. Re-expression of TRPC3 in senescent cells diminishes mitochondrial Ca2+ load and promotes escape from OIS-induced senescence. Cellular senescence evoked by TRPC3 downregulation in stromal cells displays a proinflammatory and tumour-promoting secretome that encourages cancer epithelial cell proliferation and tumour growth in vivo. Altogether, our results unravel the mechanism contributing to pro-tumour behaviour of senescent cells.

In breast cancer cells, the neurotrophin receptor p75NTR acts as a prosurvival factor able to stimulate resistance to apoptosis, but its mechanism of action remains incompletely defined. In this study, we investigated the global proteome modification induced by p75 NTR overexpression in breast cancer cells treated by the pro-apoptotic agent tumor necrosis factor (TNF)-related-apoptosis-inducing-ligand (TRAIL). p75 NTR was stably overexpressed in the MCF-7 breast cancer cells and the impact of a treatment by TRAIL was investigated in wild type vs. p75 NTR overexpressing cells. Proteins were separated in two-dimensional electrophoresis, and regulated spots were detected by computer assisted analysis before identification by MALDI-TOF/TOF mass spectrometry. In the absence of TRAIL treatment, p75 NTR did not induce any change in the proteome of breast cancer cells. In contrast, after treatment with TRAIL, fragments of cytokeratin-8, -18 and -19, as well as full length cytokeratin-18, were up-regulated by p75 NTR overexpression. Of note, spectrin alpha-chain and the ribosomal protein RPLP0 were induced by TRAIL, independently of p75 NTR level. Interestingly, the well known stress-induced protein HSP-27 was less abundant when p75 NTR was overexpressed, indicating that p75 NTR overexpression reduced TRAIL induced cell stress. These data indicate that overexpression of p75 NTR induces proteome modifications in breast cancer cells and provide information on how this receptor contributes in tumor cell resistance to apoptosis.

There is growing evidence that ion channels are critically involved in cancer cell invasiveness and metastasis. However, the molecular mechanisms of ion signaling promoting cancer behavior are poorly understood and the complexity of the underlying remodeling during metastasis remains to be explored. Here, using a variety of in vitro and in vivo techniques, we show that metastatic prostate cancer cells acquire a specific Na + /Ca 2+ signature required for persistent invasion. We identify the Na + leak channel, NALCN, which is overexpressed in metastatic prostate cancer, as a major initiator and regulator of Ca 2+ oscillations required for invadopodia formation. Indeed, NALCN-mediated Na + influx into cancer cells maintains intracellular Ca 2+ oscillations via a specific chain of ion transport proteins including plasmalemmal and mitochondrial Na + /Ca 2+ exchangers, SERCA and store-operated channels. This signaling cascade promotes activity of the NACLN-colocalized proto-oncogene Src kinase, actin remodeling and secretion of proteolytic enzymes, thus increasing cancer cell invasive potential and metastatic lesions in vivo. Overall, our findings provide new insights into an ion signaling pathway specific for metastatic cells where NALCN acts as persistent invasion controller.