Targeting EphA2 and DDR signaling can overcome the BRAF and MEK inhibitors acquired resistance in melanoma cell lines

The BRAF and MEK inhibitors combined strategies have dramatically changed the outcome of BRAF-mutated metastatic melanoma patients. However, despite the initial promising results, the onset of primary or acquired resistance occurs in nearly half of the patients at about one year from the diagnosis. Understanding the mechanisms of resistance to these inhibitors is therefore critical for planning more effective therapeutic strategies able to improve patient outcomes. To this aim we generated BRAF and MEK inhibitors resistant melanoma cells starting from the SAN and A375 lines, both harboring the most common BRAF-V600 mutation and sensitive to these drugs. The obtained double-resistant cell lines were characterized by MTT cell proliferation, migration, invasion assays, phosphoarray and western blot analysis. Here we report that the overexpression of several Tyrosine Kinase Receptors (TKRs), such as EphA2 and DDRs, drives the resistance to these drugs and that this resistance can be overcome by treatment with ALW‑II‑41‑27 multikinase inhibitor. ALW‑II‑41‑27 blocks not only TKRs expression, but also the related downstream AKT and MAPK signaling pathways and its efficacy is documented by decreased cell viability and reduced cell invasion/ migration of the resistant cells.