Acquired resistant to BRAFI sensitizes melanoma cells to OXPHOS inhibitors

ARBE, MARÍA FLORENCIA; GLIKIN G.C.; FINNOCHIARO, LME; VILLAVERDE M. S.

Congreso; Reunion Anual SAIB 2020; 2020

Near 50% of melanoma cells harbor BRAFV600E as a driver mutation. BRAFV600E inhibitors (BRAFi; like GSK2118436 also called Dabrafenib) are approved therapy agents for unresectable or metastatic melanoma with a constitutive activation of MAPK pathway. Despite their initial efficacy, BRAFi resistance is acquired at 6-8 months in 50% of patients. Tumor plasticity, including metabolic adaptations, seems to be implicated in the emergence of BRAFi resistance. In this context, the aim of the present work was to establish a GSK2118436 resistant melanoma cell line to investigate the presence of key metabolic features. A375 was significant affected by 1 uM GSK2118436 showing a decrease in cell number, glucose consumption and lactate production. However, we were able to establish A375 GSK2118436 resistant cell line (A375-R) by treating melanoma cells with increased GSK2118436 concentrations for four months. A375-R presented a significant increase in BRAFi (GSK2118436 and PLX4032) IC50 values both as monolayer and spheroids cultures. Then, we studied the effect of 9 different metabolic modulators (2-deoxyglucose/2-DG; oxamate; 6-aminonicotinamide/6-AN; metformin/MET; antimycin A; dichloroacetic acid/DCA; methotrexate/MTX; BPTES; Everolimus/RAD001). Whereas both cell lines did not present significant differences to 2-DG, oxamate, DCA and BPTES, we found that A375-R increased MTX and 6-AN IC50s and decreased MET and antimycin A IC50 values. In other words, GSK2118436 resistant cells could be sensitized with the addition of OXPHOS inhibitors such as MET and antimycin A. However, preliminary results showed that the combination of MET and GSK2118436 did not present synergistic effect when there were incubated simultaneously. Further metronomic studies are required to identify potentially benefit of this combinatory strategy.