Selective reversible inhibition of autophagy in hypoxic breast cancer cells promotes pulmonary metastasis
Menée sur des lignées cellulaires de cancer du sein et à l'aide de xénogreffes sur des modèles murins, cette étude met en évidence des mécanismes par lesquels, en empêchant la fibrose des tumeurs, l'autophagie régulée par l'hypoxie réprime la formation de métastases pulmonaires
Autophagy influences how cancer cells respond to nutrient deprivation and hypoxic stress, two hallmarks of the tumor microenvironment (TME). In this study, we explored the impact of autophagy on the pathophysiology of breast cancer cells, using a novel hypoxia-dependent, reversible dominant negative strategy to regulate autophagy at the cellular level within the TME. Suppression of autophagy via hypoxia-induced expression of the kinase-dead unc-51 like autophagy activating kinase (ULK1) mutant K46N increased lung metastases in MDA-MB-231 xenograft mouse models. Consistent with this effect, expressing a dominant-negative mutant of ULK1 or ATG4b or a ULK1-targeting shRNA facilitated cell migration in vitro. Functional proteomic and transcriptome analysis revealed that loss of hypoxia-regulated autophagy promotes metastasis via induction of the fibronectinintegrin signaling axis. Indeed, loss of ULK1 function increased fibronectin deposition in the hypoxic TME. Together, our results indicated that hypoxia-regulated autophagy suppresses metastasis in breast cancer by preventing tumor fibrosis. These results also suggest cautions in the development of autophagy-based strategies for cancer treatment.