Melanoma is the most aggressive form of skin cancer, and despite significant therapeutic advances over the past decade, a substantial number of patients still progress to a fatal outcome. The initiation and progression of melanoma are strongly influenced by interactions between melanoma cells and other components of the tumor microenvironment (TME). In this review, we focus on the interplay between fibroblasts resident in the tumor microenvironment and tumor cells. In particular, we examine the molecular mechanisms through which melanoma cells induce the transformation of resident fibroblasts into their active form, known as cancer-associated fibroblasts (CAFs). We also explore the role of CAFs in shaping the melanoma microenvironment (MME) and in organizing the pre-metastatic niche, a specialized microenvironment that forms in distant organs or tissues to support the survival and expansion of metastatic melanoma cells. Finally, we discuss emerging therapeutic strategies aimed at disrupting the interactions between CAFs, melanoma cells, and other components of the tumor microenvironment to improve treatment outcomes.

Previous studies demonstrated that integrase-strand-transfer-inhibitors (INSTIs) promote adipocyte differentiation, while nucleoside-reverse-transcriptase-inhibitors (NRTIs) tenofovir-alafenamide-fumarate (TAF) and tenofovir-disoproxil-fumarate (TDF), inhibit adipogenesis. NRTIs were shown to counteract the pro-adipogenic effects of INSTIs[6]. However, the effects of non-nucleoside-reverse-transcriptase-inhibitors (NNRTIs) and of the novel long-acting INSTI cabotegravir (CAB), on adipogenesis, alone or in combination with NRTIs or other INSTIs, remain unclear. This study aims to elucidate the impact of NNRTIs and recent INSTIs on adipogenesis. 3T3-L1 cells were used as an adipogenesis in vitro model. The NNRTIs doravirine (DOR) and rilpivirine (RPV) were tested alone and in combination with DTG, CAB, TDF, TAF. Adipogenesis was assessed by Oil-Red-O-staining and by measuring expression-levels of peroxisome-proliferator-activated-receptor-gamma (PPARγ) and CCAAT/enhancer-binding-protein-alpha (C/EBPα). Moreover, Fibroblast-marker ER-TR7 was assessed by immunohistochemistry. CAB, DOR, and RPV promoted adipogenesis, with CAB and DOR showing greater effects. In combination, NNRTIs enhanced the adipogenic effects of CAB and DTG. Conversely, TAF and TDF, when paired with RPV or DOR, inhibited adipogenesis. NNRTIs and CAB increased ER-TR7 expression, suggesting fibroblastic differentiation. Finally, NNRTIs and INSTIs promote adipogenesis and induce fibroblastic features in 3T3-L1 cells. Contrarily, TAF and TDF exhibited an antagonistic effect on adipogenesis when combined with certain antiretrovirals, supporting our previous research.