Comparative Proteomic Analysis of the Secretome of Control and BRAF/MEK Inhibitor-Resistant Melanoma Cells

Treatment based on BRAF/MEK kinase inhibitors is one of the most commonly used methods in advanced melanoma therapy, but patients often develop resistance to treatment. Treatment-resistant cells can affect other cancer cells and the tumor microenvironment through the factors that they secrete. Therefore, this study aimed to examine the protein composition of the secretome of cells resistant to vemurafenib (a BRAF inhibitor) and cobimetinib (a MEK inhibitor) and to compare it with that of nonresistant cells. Proteomic analysis, followed by gene ontology (GO) analysis, identified many differences in resistant melanoma cells' secretomes compared to controls (nonresistant). Many proteins upregulated in resistant melanoma cells compared to their nonresistant variants were directly related to cancer progression and associated with cell adhesion, actin cytoskeleton, matrix organization, proteolysis, and drug resistance. Proteins secreted by resistant melanoma cells can undoubtedly influence the surrounding microenvironment in a way that promotes the formation of a pro-tumor niche. Among the proteins secreted in significantly higher amounts by resistant cells (compared to the control group), which may be potential biomarkers or therapeutic targets in melanoma, plasminogen activator inhibitor 1, thymosin beta-4, clusterin, interleukin-6, superoxide dismutase, and selected matrix metalloproteinases can be distinguished.