Endothelial-to-mesenchymal transition induces CAFs formation, which promote tumor growth, immunosuppression and metastasis. It is not described in melanoma, therefore we aimed to study the ability of melanoma cells to activate EndMT of endothelial cells. Human Umbilical Vein Endothelial Cells (HUVEC) were treated with conditioned medium (CM) from SK-MEL-28 melanoma cells. Analysis of protein expression (α-SMA and vonWillebrand Factor) was conducted by Western-blot. α-SMA and vWF double-stained cells were detected by FACS. Cell functional capacities were evaluated with wound healing and cell proliferation assays. TGF-β signaling pathway was analyzed through qRT-PCR and Western blot (pSMAD/SMAD and Snail). A significant increase of α-SMA expression in HUVEC was observed after 48 hours of treatment with CM as well as a slight decrease of vWF proteic expression. These findings have been confirmed by FACS analyses: a significant increase in the percentage of double-stained cells (α-SMA/vWF) has been shown after 48 hours. After 72 hours, there was a slight decrease of vWF expression. Moreover, wound healing and cell proliferation assays exhibited enhanced migration and proliferation of endothelial cells treated with CM compared to control cells. Finally, n the presence of CM, an increase in the p-Smad/Smad ratio and Snail was observed compared to control cells while no change in tgfβ1 gene expression was noticed. These data show that SK-MEL-28 cells induce a phenotypic modification of endothelial cells towards a mesenchymal profile according to a mechanism independent of the TGF-β pathway. The maintenance of endothelial markers suggests a partial and potentially reversible transition. Increased cell migration and proliferation indicate the likely formation of CAFs. Further work is required to identify the involved mediators in this process. These mediators may constitute, in the future, potential new therapeutic targets for metastatic melanoma.

ESDR273 - Melanoma cells conditioned-medium induces endothelial-to-mesenchymal transition of endothelial cells

50th Annual Meeting of the European Society for Dermatological Research. VIRTUAL MEETING