INHIBITION OF AUTOPHAGOSOMAL DEGRADATION IN MELANOMA CELLS PROMOTES THE RELEASE OF MEDIATORS THAT INCREASE GLOBAL RESISTANCE TO VEMURAFENIB

FALCÓN CRISTIAN ROBERTO; ZURITA., ADOLFO R.; CUELLO ORLANDI SERGIO FEDERICO; SANGIACOMO RUIZ MERCEDES L; IBAÑEZ ITATÍ; MONS JOHINA; PEREZ CELIA; ALVAREZ SERGIO

Mar del Plata

Congreso; REUNIÓN CONJUNTA SAIC SAI&FAIC SAFIS 2022; 2022

Sociedad Argentina de investigación Clínica

Vemurafenib (Vem) is used in the treatment of melanomasthat have the BRAFV600E mutation but resistanceto this drug is rapidly induced. Autophagy has been implicatedin resistance to Vem. Objective: to study the influenceof autophagosomal degradation inhibition on resistanceto Vem in human melanoma cells. Results: Lu1205cells cultured in hypoxia (Hx) have higher resistance toVem than in normoxia (Nx). We show by western blot thatHx produces accumulation of LC3 and p62, indicating decreasedautophagic flux. Although autophagy inhibitionwith NH4Cl or Chloroquine (Cq) in Nx and Hx increasedsensitivity to Vem (MTT viability and apoptosis), onlyconditioned media (CM) from cultures in Hx transferredVem resistance to sensitive cells and this ability was notsignificantly modified by autophagy inhibitors. Surprisingly,CM from Lu1205 cultured in Nx with NH4Cl or Cqincreased the resistance to Vem of sensitive cells, similarlyto CM-Hx. In addition, we developed a novel cell linederived from Lu1205 cells expressing the M2 protein ofthe influenza virus A/PR8 strain, which inhibits the autophagosome-lysosome fusion. These cells (Lu1205-M2iv)showed increased resistance to Vem both in Nx and Hxand augmented migratory capacity with respect to theparental line. In addition, CM obtained from Lu1205-M2iv cells enhanced chemoattraction of PMA-differentiatedTHP-1 cells and transferred resistance to sensitivecells. Finally, Lu1205 cells with acquired resistance toVem (Lu1205R) showed strongly decreased autophagicflux and increased expression of mRNA of RAB27aand RAB27b involved in excretory pathways. These cellssubtly decreased their viability when cultured with Vemin the presence of the autophagy inhibitors and showedan increased ability to induce Vem resistance in sensitivecells. Conclusion: Therapy with inhibitors of autophagosomaldegradation in melanoma cells increases initialsensitivity to Vem but could promote the general tumorresistance to treatment.