EGFR/uPAR interaction as druggable target to overcome vemurafenib acquired resistance in melanoma cellsResearch in context
Anna Laurenzana,
Francesca Margheri,
Alessio Biagioni,
Anastasia Chillà,
Nicola Pimpinelli,
Jessica Ruzzolini,
Silvia Peppicelli,
Elena Andreucci,
Lido Calorini,
Simona Serratì,
Mario Del Rosso,
Gabriella Fibbi
Affiliations
Anna Laurenzana
Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Viale G.B. Morgagni, 50, 50134 Florence, Italy; Corresponding authors.
Francesca Margheri
Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Viale G.B. Morgagni, 50, 50134 Florence, Italy
Alessio Biagioni
Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Viale G.B. Morgagni, 50, 50134 Florence, Italy
Anastasia Chillà
Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Viale G.B. Morgagni, 50, 50134 Florence, Italy
Nicola Pimpinelli
Dermatology Unit, Department of Surgery and Translational Medicine, University of Florence, Viale Michelangiolo, 41, 50125 Florence, Italy
Jessica Ruzzolini
Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Viale G.B. Morgagni, 50, 50134 Florence, Italy
Silvia Peppicelli
Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Viale G.B. Morgagni, 50, 50134 Florence, Italy
Elena Andreucci
Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Viale G.B. Morgagni, 50, 50134 Florence, Italy
Lido Calorini
Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Viale G.B. Morgagni, 50, 50134 Florence, Italy
Simona Serratì
Nanotecnology Laboratory, National Cancer Research Centre, IRCCS “Giovanni Paolo II”, Viale Orazio Flacco, 65, 70124 Bari, Italy
Mario Del Rosso
Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Viale G.B. Morgagni, 50, 50134 Florence, Italy; Corresponding authors.
Gabriella Fibbi
Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Viale G.B. Morgagni, 50, 50134 Florence, Italy
Background: BRAF inhibitor (BRAF-I) therapy for melanoma patients harboring the V600E mutation is initially highly effective, but almost all patients relapse within a few months. Understanding the molecular mechanisms behind BRAF-I responsiveness and acquired resistance is therefore an important issue. Here we assessed the role of urokinase type plasminogen activator receptor (uPAR) as a potentially valuable biomarker in the acquisition of BRAF-I resistance in V600E mutant melanoma cells. Methods: We examined uPAR and EGFR levels by real time PCR and western blot analysis. uPAR loss of function was realized by knocking down uPAR by RNAi or using M25, a peptide that uncouples uPAR-integrin interaction. We investigated uPAR-β1integrin-EGFR association by co-immunoprecipitation and confocal immuno-fluorescence analysis. Acquired resistance to BRAF-I was generated by chronic exposure of cells to vemurafenib. Findings: We proved that uPAR knockdown in combination with vemurafenib inhibits melanoma cell proliferation to greater extent than either treatment alone causing a decrease in AKT and ERK1/2 phosphorylation. Conversely, we demonstrated that uPAR enforced over-expression results in reduced sensitivity to BRAF inhibition. Moreover, by targeting uPAR and EGFR interaction with an integrin antagonist peptide we restored vemurafenib responsiveness in melanoma resistant cells. Furthermore, we found significant detectable uPAR and EGFR levels in tumor biopsies of 4 relapsed patients. Interpretation: We disclosed an unpredicted mechanism of reduced sensitiveness to BRAF inhibition, driven by elevated levels of uPAR and identified a potential therapeutic strategy to overcome acquired resistance. Funds: Associazione Italiana Ricerca sul Cancro (AIRC); Ente Cassa di Risparmio di Firenze. Keywords: Vemurafenib, Acquired resistance, Melanoma, uPAR, EGFR
