Down Regulation of SIRT2 Reduced ASS Induced NSCLC Apoptosis Through the Release of Autophagy Components via Exosomes

Lei Wang,Lianyong Jiang,Rui Hu,Fengqing Hu,Pei Xu,Haibo Xiao,Huijun Zhang,Fangbao Ding,Xiao Xie

doi:10.3389/fcell.2020.601953

Abstract

Metastasis of cancer is the main cause of death in many types of cancer. Acute shear stress (ASS) is an important part of tumor micro-environment, it plays a crucial role in tumor invasion and spread. However, less is known about the role of ASS in tumorigenesis and metastasis of NSCLC. In this study, NSCLC cells were exposed to ASS (10 dyn/cm2) to explore the effect of ASS in regulation of autophagy and exosome mediated cell survival. Finally, the influence of SIRT2 on NSCLC cell metastasis was verified in vivo. Our data demonstrates that ASS promotes exosome and autophagy components releasing in a time dependent manner, inhibition of exosome release exacerbates ASS induced NSCLC cell apoptosis. Furthermore, we identified that this function was regulated by sirtuin 2 (SIRT2). And, RNA immunoprecipitation (RIP) assay suggested SIRT2 directly bound to the 3′UTR of transcription factor EB (TFEB) and facilitated its mRNA stability. TFEB is a key transcription factor involved in the regulation of many lysosome related genes and plays a critical role in the fusion of autophagosome and lysosome. Altogether, this data revealed that SIRT2 is a mechanical sensitive protein, and it regulates ASS induced cell apoptosis by modulating the release of exosomes and autophagy components, which provides a promising strategy for the treatment of NSCLCs.

Highlights

Lung cancer stands as the leading cause of cancer-related deaths world-wide (Siegel et al, 2019)
In order to further characterize Acute shear stress (ASS) induced autophagy, A549 cells were exposed to ASS (10 dyn/cm2) for varying lengths of time (0, 15, 30, and 60 min), which were further characterized by Transmission Electron Microscopy (TEM)
From the TEM images obtained at different times, it was evident that exposure to ASS increased the formation of autophagosomes in a time-dependent manner

Summary

Introduction

Lung cancer stands as the leading cause of cancer-related deaths world-wide (Siegel et al, 2019). In spite of the negative effects of SS, studies have indicated lowshear stress enhances migration, proliferation, and differentiation of circulating tumor cells (CTCs) (Sebastian et al, 2020). Autophagy has varying roles in multiple cell types, critically cancer cells depend on autophagy to maintain a minimal metabolic requirement and survive under harsh conditions through self-degradation of organelles and protein aggregates (Mowers et al, 2018). A study by Latifkar et al (2019), indicated that SIRT1 down-regulation altered the secretome and increased the exosome release in breast cancer cell lines. This study further indicated that SIRT1 reduced the tumorigenesis of breast cancer by altering the lysosomal activity. Sirtuin’s role in NSCLC is still not clear

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