Rabbit Anti-Human mTOR Polyclonal antibody

In the last few decades, studies on autophagy regulation and its potential role in cancer therapeutics have expanded to include detailed mechanisms. Since apoptosis exhibits drug resistance in some cancers, efforts have focused on searching for compounds with autophagy modulating properties. Numerous natural compounds have been used in cancer treatment and are considered a significant research area due to their remarkable anti-cancer properties. Celastrol, a quinone methide triterpene, derived from Tripterygium wilfordii, has recently drawn much attention because of its anticancer potential. It enhances tumor suppression and induces autophagy in cancer cells by regulating signaling pathways such as Beclin-1, Akt/mTOR, ROS, NF-kappa B, MAPK, HSP90, and the proteasome. In the current study, we address the anticancer potential of celastrol, its effect on various cellular pathways, and describe how it functions as an autophagy modulator in cancer therapeutics and helps diminish multidrug resistance in cancer cells.

Background & Aims: Autophagy plays a crucial role in hepatic homeostasis and its deregulation has been associated with chronic liver disease. However, the effect of autophagy on the release of fibrogenic extracellular vesicles (EVs) by platelet-derived growth factor (PDGF)-stimulated hepatic stellate cells (HSCs) remains unknown. Herein, we aimed to elucidate the role of autophagy, specifically relating to fibrogenic EV release, in fibrosis. Methods: In vitro experiments were conducted in primary human and murine HSCs as well as LX2 cells. Small EVs were purified by differential ultracentrifugation. Carbon tetrachloride (CCl4) or bile duct ligation (BDL) were used to induce fibrosis in our mouse model. Liver lysates from patients with cirrhosis or healthy controls were compared by RNA sequencing. Results: In vitro, PDGF and its downstream molecule SHP2 (Src homology 2-containing protein tyrosine phosphatase 2) inhibited autophagy and increased HSC-derived EV release. We used this PDGF/SHP2 model to further investigate how autophagy affects fibrogenic EV release. RNA sequencing identified an mTOR (mammalian target of rapamycin) signaling molecule that was regulated by SHP2 and PDGF. Disruption of mTOR signaling abolished PDGF-dependent EV release. Activation of mTOR signaling induced the release of multivesicular body-derived exosomes (by inhibiting autophagy) and microvesicles (by activating ROCK1 signaling). These mTOR-dependent EVs promoted in vitro HSC migration. To assess the importance of this mechanism in vivo, SHP2 was selectively deleted in HSCs, which attenuated CCl4- or BDL-induced liver fibrosis. Furthermore, in the CCl4 model, mice receiving circulating EVs derived from mice with HSC-specific Shp2 deletion had less fibrosis than mice receiving EVs from control mice. Correspondingly, SHP2 was upregulated in patients with liver cirrhosis. Conclusion: These results demonstrate that autophagy in HSCs attenuates liver fibrosis by inhibiting the release of fibrogenic EVs. Lay summary: During liver fibrosis and cirrhosis, activated hepatic stellate cells (HSCs) are the key cell type responsible for fibrotic tissue deposition. Recently, we demonstrated that activated HSCs release nano-sized vesicles enriched with fibrogenic proteins. In the current study, we unveil the mechanism by which these fibrogenic vesicles are released, moving a step closer to the long-term goal of therapeutically targeting this process. (C) 2020 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.