Participation of Gas6 ligand in the interaction of melanoma cells and fibroblasts

Trabajo fin de máster presentado en la Universidad de Barcelona, Official Master in Translational MedicineGrowth arrest specific 6 (Gas6) is a secreted protein part of the vitamin K-dependent family that exerts its biological activity through the TAM tyrosine kinase receptors (Tyro3, Axl and Mertk). This system is involved in inflammation response, platelet aggregation, viral infection, and cancer. Specifically in cancer, Gas6/TAM downstream signalling promotes cell survival, invasion, and metastasis, with a particular prominence in Epithelial to Mesenchymal Transmission processes and microenvironment crosstalk signalling. This project aims to investigate the role of the Gas6/TAM system in melanoma, a cancer known for its complex and aggressive nature. While the involvement of TAMs in melanoma cell-intrinsic pathways has been studied before, the specific mechanisms by which the paracrine activity of Gas6 contributes to the creation of a tumor-permissive microenvironment remain poorly understood. To investigate the impact of Gas6 in the tumor microenvironment, we employed a spheroid culture system to generate melanospheres. Murine melanoma B16F10-GTP cells, control and Gas6-expressing, were cultured in ultra-low attachment plates to facilitate the formation of spheroids and treated with two drugs targeting AXL. Additionally, to mimic the tumor milieu, we incorporated lung fibroblasts into the culture system. We also performed a bioinformatic analysis that highlighted fibroblasts as a significant single-cell expression cluster for Gas6, which aligns with our investigation of the metastatic microenvironment using lung fibroblasts. Our findings demonstrate that Gas6 expression in melanospheres enhances melanin synthesis, promotes cellular viability, and influences the response to drug treatments, shedding light on its functional significance in melanoma progression and potential as a therapeutic target