Autophagy is a lysosome-dependent cellular catabolic mechanism that mediates the turnover of intracellular organelles and long-lived proteins associated with a broad spectrum of human diseases. It protects organelles, cells, and organisms against several stress conditions. In some cellular settings, autophagy suppresses apoptosis, while in others it induces cell death, either in collaboration with apoptosis or as a back-up mechanism when the former is defective. Recently, a cross-talk between autophagy and apoptosis has been considered as a key factor in the development and treatment of cancer. We have previously demonstrated that the thiazole derivative 3-methylcyclopentylidene-[4-(4’-chlorophenyl)thiazol-2-yl]hydrazone (CPTH6) induces apoptosis and cell cycle arrest in human leukemia cells. The aim of this study was to evaluate whether CPTH6 is able to affect other cell death mechanisms, such as autophagy. We found that treatment of human cancer cell lines with CPTH6 and other compounds having high structural similarities with it, induced in a dose-dependent manner hallmarks of autophagy including the convertion of microtubule-associated protein 1 light chain 3 (LC3B-I) to LC3B-II, and the appearance of typical LC3B-II associated autophagosomal puncta in cells stably overexpressing EGFP-LC3. Strikingly, combined treatment of CPTH6 with late stage autophagy inhibitors, such as chloroquine and bafilomycin A1, demonstrates that CPTH6 reduces autophagosomes turnover through an impairment of their degradation pathway, rather than enhancing autophagosomes formation. According to these results, the enhancement of autophagy substrates p62 and NBR1 protein levels, confirms a blockage of autophagic cargo degradation. Finally, CPTH6 inhibits autophagosome maturation by impairing autophagosome-lysosome fusion. Most importantly, antitumor activity is observed without toxicity in mice carring human acute myeloid leukemia xenografts treated with CPTH6. Overall, CPTH6 could be a valuable agent for the treatment of cancer patients and should be further developed as a antineoplastic agent.
Modulation of autophagic flux by CPTH6, a thiazole derivative with antitumoral activity / Ragazzoni, Ylenia; M., Desideri; C., Gabellini; Carradori, Simone; Nescatelli, Riccardo; Secci, Daniela; A., Candiloro; D., Trisciuoglio; D., Del Bufalo. - (2012). (Intervento presentato al convegno 25° Convegno Annuale dell’Associazione Italiana di Colture Cellulari (ONLUS-AICC) 3rd International Satellite Symposium AICC–GISM."Controllo dei processi di proliferazione e morte cellulare: nuovi sviluppi della ricerca oncologica preclinica" tenutosi a Palermo nel 21-23/11/2012).
Modulation of autophagic flux by CPTH6, a thiazole derivative with antitumoral activity
RAGAZZONI, YLENIA;CARRADORI, Simone;NESCATELLI, RICCARDO;SECCI, DANIELA;
2012
Abstract
Autophagy is a lysosome-dependent cellular catabolic mechanism that mediates the turnover of intracellular organelles and long-lived proteins associated with a broad spectrum of human diseases. It protects organelles, cells, and organisms against several stress conditions. In some cellular settings, autophagy suppresses apoptosis, while in others it induces cell death, either in collaboration with apoptosis or as a back-up mechanism when the former is defective. Recently, a cross-talk between autophagy and apoptosis has been considered as a key factor in the development and treatment of cancer. We have previously demonstrated that the thiazole derivative 3-methylcyclopentylidene-[4-(4’-chlorophenyl)thiazol-2-yl]hydrazone (CPTH6) induces apoptosis and cell cycle arrest in human leukemia cells. The aim of this study was to evaluate whether CPTH6 is able to affect other cell death mechanisms, such as autophagy. We found that treatment of human cancer cell lines with CPTH6 and other compounds having high structural similarities with it, induced in a dose-dependent manner hallmarks of autophagy including the convertion of microtubule-associated protein 1 light chain 3 (LC3B-I) to LC3B-II, and the appearance of typical LC3B-II associated autophagosomal puncta in cells stably overexpressing EGFP-LC3. Strikingly, combined treatment of CPTH6 with late stage autophagy inhibitors, such as chloroquine and bafilomycin A1, demonstrates that CPTH6 reduces autophagosomes turnover through an impairment of their degradation pathway, rather than enhancing autophagosomes formation. According to these results, the enhancement of autophagy substrates p62 and NBR1 protein levels, confirms a blockage of autophagic cargo degradation. Finally, CPTH6 inhibits autophagosome maturation by impairing autophagosome-lysosome fusion. Most importantly, antitumor activity is observed without toxicity in mice carring human acute myeloid leukemia xenografts treated with CPTH6. Overall, CPTH6 could be a valuable agent for the treatment of cancer patients and should be further developed as a antineoplastic agent.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
