Azithromycin, a potent autophagy inhibitor for cancer therapy, perturbs cytoskeletal protein dynamics
Menée à l'aide de lignées cellulaires de cancer du poumon, de myélome multiple et d'adénocarcinome surrénalien ainsi qu'à l'aide d'une xénogreffe sur un modèle murin, cette étude met en évidence un mécanisme par lequel l'azithromycine inhibe l'autophagie des cellules cancéreuses en perturbant la dynamique des protéines du cytosquelette
Background : Autophagy plays an important role in tumour cell growth and survival and also promotes resistance to chemotherapy. Hence, autophagy has been targeted for cancer therapy. We previously reported that macrolide antibiotics including azithromycin (AZM) inhibit autophagy in various types of cancer cells in vitro. However, the underlying molecular mechanism for autophagy inhibition remains unclear. Here, we aimed to identify the molecular target of AZM for inhibiting autophagy. Methods : We identified the AZM-binding proteins using AZM-conjugated magnetic nanobeads for high-throughput affinity purification. Autophagy inhibitory mechanism of AZM was analysed by confocal microscopic and transmission electron microscopic observation. The anti-tumour effect with autophagy inhibition by oral AZM administration was assessed in the xenografted mice model. Results : We elucidated that keratin-18 (KRT18) and
α/β-tubulin specifically bind to AZM. Treatment of the cells with AZM disrupts intracellular KRT18 dynamics, and KRT18 knockdown resulted in autophagy inhibition. Additionally, AZM treatment suppresses intracellular lysosomal trafficking along the microtubules for blocking autophagic flux. Oral AZM administration suppressed tumour growth while inhibiting autophagy in tumour tissue. Conclusions
:
As drug-repurposing, our results indicate that AZM is a potent autophagy inhibitor for cancer treatment, which acts by directly interacting with cytoskeletal proteins and perturbing their dynamics.