The FDA-approved BRAF inhibitor
vemurafenib achieves outstanding clinical response rates in patients with
melanoma, but early resistance is common. Understanding the pathologic mechanisms of drug resistance and identification of effective therapeutic alternatives are key scientific challenges in the
melanoma setting. Using proteomic techniques, including shotgun analysis and 2D-gel electrophoresis, we identified a comprehensive signature of the
vemurafenib-resistant M24met in comparison with the
vemurafenib-sensitive A375
melanoma cell line. The resistant cells were characterized by loss of differentiation, induction of transformation, enhanced expression of the lysosomal compartment, increased potential for
metastasis, migration, adherence and Ca2(+) ion binding, enhanced expression of the MAPK pathway and
extracellular matrix proteins, and epithelial-mesenchymal transformation. The main features were verified by shotgun analysis with QEXACTIVE orbitrap MS, electron microscopy, lysosomal staining, Western blotting, and adherence assay in a VM-1
melanoma cell line with acquired
vemurafenib resistance. On the basis of the resistance profile, we were able to successfully predict that a novel
resveratrol-derived
COX-2 inhibitor, M8, would be active against the
vemurafenib-resistant but not the
vemurafenib-sensitive
melanoma cells. Using high-throughput methods for cell line and
drug characterization may thus offer a new way to identify key features of
vemurafenib resistance, facilitating the design of effective rational therapeutic alternatives.