Discovery of LAMP-2A as potential biomarkers for glioblastoma development by modulating apoptosis through N-CoR degradation

Yongjie Wang,Haijian Wu,Buyi Zhang,Jianli Wang,Lin Wang,Shenbin Xu,Jianmin Zhang

doi:10.1186/s12964-021-00729-8

Abstract

BackgroundLysosome-associated membrane protein type 2A (LAMP-2A) is the key component of chaperone-mediated autophagy (CMA), a cargo-selective lysosomal degradation pathway. Aberrant LAMP-2A expression and CMA activation have been demonstrated in various human malignancies. The study focusing on the intrinsic role of LAMP-2A and CMA in glioblastoma (GBM), and downstream mechanism could provide valuable insight into the pathogenesis and novel therapeutic modality of GBM.MethodsThe levels of LAMP-2A, nuclear receptor co-repressor (N-CoR), unfolded protein response (UPR) and apoptosis were examined in clinical samples. LAMP-2A siRNA and shRNA were constructed to manipulate CMA activation. The role of CMA and downstream mechanism through degradation of N-CoR and arresting UPR mediated apoptosis were explored in GBM cells and nude mouse xenograft model.ResultsElevated LAMP-2A and associated decreased N-CoR expression were observed in GBM as compared with peritumoral region and low-grade glioma. Inhibited UPR and apoptosis were observed in GBM with high LAMP-2A expression. In vitro study demonstrated co-localization and interaction between LAMP-2A and N-CoR. LAMP-2A silencing up-regulated N-CoR and aroused UPR pathway, leading to apoptosis, while N-CoR silencing led to an opposite result. In vivo study further confirmed that LAMP-2A inhibition arrested tumor growth by promoting apoptosis.ConclusionsOur results demonstrated the central role of CMA in mediating N-CoR degradation and protecting GBM cells against UPR and apoptosis, and provided evidence of LAMP-2A as potential biomarker. Further research focusing on CMA with other tumorigenic process is needed and selective modulators of LAMP-2A remain to be investigated to provide a novel therapeutic strategy for GBM.Ci7JAW8nJL_a3Xcmr9Ld2GVideo .

Highlights

Lysosome-associated membrane protein type 2A (LAMP-2A) is the key component of chaperonemediated autophagy (CMA), a cargo-selective lysosomal degradation pathway
Expression of LAMP‐2A in different regions of GBM and Low grade glioma (LGG) To determine the expressive profile of LAMP-2A in clinical samples, we analyzed mRNA by Quantitative real-time RT-PCR (qRT-PCR), protein by western blot (WB), in-situ tissue expression by immunohistochemistry (IHC) and immunofluorescence (IF) in GBM center, Peri-tumor edema zone (PTEZ) of GBM and LGG
Significant down-regulation of p-pancreatic endoplasmic reticulum (ER) kinase (PERK), p-inositol requiring enzyme 1 (IRE1), p-JUN N-terminal kinase (JNK) and C/EBP homologous protein (CHOP) was observed in the High group as compared with the Low group. c Activator proteins in apoptosis including caspase 3, caspase 9 and Bax, and anti-apoptotic protein Bcl-2 were measured by western blot

Summary

Introduction

Lysosome-associated membrane protein type 2A (LAMP-2A) is the key component of chaperonemediated autophagy (CMA), a cargo-selective lysosomal degradation pathway. Insights into the potential biomarkers and molecular mechanism for GBM development and progression still remain important in seeking new effective therapeutic targets. Chaperonemediated autophagy (CMA), on the contrary, is a highly selective degradation process targeting KFERQ-likemotif-bearing proteins, during which the substrates are recognized by heat shock cognate 71 kDa protein (Hsc70) and co-chaperones, and delivered to the surface of the lysosome where they bind to lysosomal associated membrane protein 2A (LAMP-2A) and undergo unfolding, and are translocated into the lysosomes where they are rapidly degraded [5,6,7]. The intrinsic function of LAMP-2A and CMA in GBM development and progression has been poorly elucidated

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