IntroductionMelanoma is a skin neoplasia originated from transformed melanocytes, which may acquire the capacity of invasion through dermis. Despite of its low incidence (232.000 cases globally), it is one of the most lethal cancers (55.500 deaths, GLOBOCAN 2012). One of the factors that correlates with its malignant phenotype is the presence of Protease-Activated Receptor 1 (PAR1), which is overexpressed in melanoma and metastatic lesions. PAR1 can be activated in two different ways: 1) the canonical pathway (CP) – when the receptor is cleaved by thrombin at Arg41; and 2) the non-canonical pathway (NCP) – when other proteases cleave a distinct peptide bond in the PAR1 N-terminal region. The CP activation leads to an increased secretion of pro-angiogenic factors by tumour cells as well as pro-inflammatory effects in models of inflammation. On the other hand, the NCP activation by Activated Protease C (APC), in endothelial cells, evoke in vitro and in vivo antitumor effects. There are no studies describing the direct effects of NCP activation in melanoma cells. The aim of this work was to stablish an in vitro model to evaluate the effects of the NCP activation of PAR1 in cultured melanoma cells.Material and methodsIn order to establish representative models, the lineages A375 (harbouring an activating BRAF -V600E mutation) and FM-6 (wild-type BRAF) were used. The agonists TR41 (SFLLRNPN-NH2) and TR47 (NPNDKYEP-NH2) were used to mimic CP and NCP PAR1 cleavages, respectively. PAR1 expression was evaluated by qPCR and flow cytometry. The effects of PAR1 activation were evaluated by p-ERK detection, cell proliferation assays, analysis of IL-8, VEGF and MMP-9 expression and migration assays.Results and discussionsBoth lineages expressed high levels of PAR1. A transient reduction in the ERK-p was observed upon treatment of either A375 or FM-6 with TR47, while no effects were observed for TR41. Treatment with TR41 increased the proliferation of both cell lines after 24 or 48 hour. A slight decrease in proliferation and transient reduction in VEGF expression were observed when both lineages were incubated with TR47. Finally, it was observed that treatment with TR47 for 18 hs reduced the migratory properties of A375 but not FM-6.ConclusionTaken together, our preliminary results show, for the first time in melanoma cell lines, that the NCP PAR1 agonist might modulate cultured tumour cells. However further studies are necessary to establish the role of NCP activation of PAR1 in cancer models and its possible utility in a therapeutic way.