Cx43 Enhances Response to BRAF/MEK Inhibitors by Reducing DNA Repair Capacity

BRAF and MEK inhibitors (BRAF/MEKi) have radically changed the treatment landscape of advanced BRAF mutation-positive tumours. However, limited efficacy and emergence of drug resistance are major handicaps for successful treatments. Here, by using relevant preclinical models, we found that Connexin43 (Cx43), a protein that plays a role in cell-to-cell communication, increases effectiveness of BRAF/MEKi by recruiting DNA repair complexes to lamin-associated domains and promoting persistent DNA damage and cellular senescence. The nuclear compartmentalization promoted by Cx43 contributes to genome instability and synthetic lethality caused by excessive DNA damage, which could lead to a novel therapeutic approach for these tumours to overcome drug resistance. Based on these findings, we designed an innovative drug combination using small extracellular vesicles (sEVs) to deliver the full-Cx43 in combination with the BRAF/MEKi. This study reveals Cx43 as a new player on DNA repair and BRAF/MEKi response, underlining the therapeutical potential that this approach could eventually have in the clinic to overcome the limitations of current therapies and improve treatment outcomes for patients with advanced BRAF mutant tumours.