Alcon, ClaraKovatcheva, MartaMorales Sánchez, PaulaLópez Polo, VanessaTorres, TeresaPuig, SusanaLu, AlbertSamitier i Martí, JosepEnrich Bastús, CarlesSerrano, ManuelMontero Boronat, Joan2025-03-062025-03-062024-12-031350-9047https://hdl.handle.net/2445/219509Senescent cells are commonly detected in tumors after chemo and radiotherapy, leading to a characteristic cellular phenotype that resists apoptotic cell death. In this study, we used multiple melanoma cell lines, molecular markers, and therapies to investigate the key role of the BCL-2 family proteins in the survival of senescent cells. We first used BH3 profiling to assess changes in apoptotic priming upon senescence induction. Unexpectedly, not all cell types analyzed showed a decrease in apoptotic priming, BIM was downregulated, there was variability in BAX expression and BAK remained constant or increased. Therefore, there was not a clear pattern for pro-survival adaptation. Many studies have been devoted to find ways to eliminate senescent cells, leading to one of the most studied senolytic agents: navitoclax, a promiscuous BH3 mimetic that inhibits BCL-2, BCL-xL and BCL-W. While it is known that the BCL-2 family of proteins is commonly upregulated in senescent cells, the complexity of the apoptotic network has not been fully explored. Interestingly, we found distinct protein expression changes always leading to a BCL-xL mediated pro-survival adaptation, as assessed by BH3 profiling. When analyzing potential therapeutic strategies, we observed a stronger senolytic activity in these melanoma cell lines when specifically targeting BCL-xL using A-1331852, navitoclax or the PROTAC BCL-xL degrader DT2216. We found that the sensitizer protein HRK was systematically downregulated when senescence was induced, leading to an increased availability of BCL-xL. Furthermore, we identified that the main apoptotic inhibition was shaped by BCL-xL and BAK binding increase that prevented mitochondrial permeabilization and apoptosis. To our knowledge, this is the first time that the molecular basis for BCL-xL anti-apoptotic adaptation in senescence is described, paving the way for the development of new molecules that either prevent HRK downregulation or displace BCL-xL binding to BAK to be used as senolytics.11 p.application/pdfengcc-by (c) (c) Alcon, Clara et al., 2024http://creativecommons.org/licenses/by/3.0/es/RadioteràpiaQuimioteràpia del càncerCèl·lulesProteïnesMort cel·lularRadiotherapyCancer chemotherapyCellsProteinsCell deathinfo:eu-repo/semantics/article7529152025-03-06info:eu-repo/semantics/openAccess39627361