However, a dual role of MA suppressing or promoting tumor progression has been described in GBM ( 2). In GBM, MA activity has been associated with the metabolism and phenotype of glioma stem cells (GSC), a subpopulation of cells responsible for tumor progression, therapy resistance, and relapse ( 10, 11). However, once cellular damage gets accumulated, cancer cells deregulate MA and CMA, which facilitate their survival or cell death promotion depending on the context and stage of the tumor ( 8, 9). Herein, the cargo protein is directly translocated across the lysosomal membrane for its degradation ( 4).ĭuring homeostasis, CMA can be activated in the presence of stress such as starvation ( 5), oxidative stress ( 6), or genotoxic insults ( 7), and both, MA and CMA, protect cells against malignant transformation, by the preservation of cellular integrity or inactivating neoplastic precursors, among others ( 8, 9). In this latest type, heat shock cognate 71 kDa protein (HSC70) chaperone recognizes cytosolic proteins containing a “KFERQ”-like motif and targets them to the lysosome-associated membrane protein type 2A (LAMP2A), the key limiting mediator of CMA ( 4). CMA is a unique selective type of autophagy specialized in the targeting and translocation of individual proteins for their degradation within the lysosome ( 4). MA is specialized in the removal of abnormal proteins, damaged organelles or invading pathogens by activating the formation of double-membrane vesicles, whereas microautophagy delivers cargo to the lysosome through direct invagination of the lysosomal membrane ( 3). They differ on how cargo is delivered to lysosomes for degradation.

To date, three main types of autophagy have been described in mammals, which include macroautophagy (MA), microautophagy, and chaperone-mediated autophagy (CMA). In conclusion, we identified a novel role of CMA in directly regulating GSCs activity via multiple pathways at the proteome and transcriptome levels.Īutophagy is a key process to maintain cellular homeostasis in response to various stimuli, based on the recycling of cytoplasmic content and elimination of damaged molecules via lysosomal degradation. Furthermore, clinical samples of GBM tissue presented overexpression of LAMP2, which correlated with advanced glioma grade and poor overall survival. Moreover, pathways related to mitochondrial metabolism and the immune system were differentially deregulated at the proteome level. Proteomic and transcriptomic analysis of LAMP2A-depleted GSCs revealed reduced extracellular matrix interaction effectors in both analyses. Conversely, overexpression of LAMP2A facilitates the acquisition of GSC properties. In this work, we show that LAMP2A expression is enriched in patient-derived GSCs, and its depletion diminishes GSC-mediated tumorigenic activities. However, the role of LAMP2A, and hence CMA, in any cancer stem cell type or in glioblastoma stem cells (GSC) remains unknown. In glioblastoma (GBM), the most common and aggressive brain cancer in adulthood, high levels of LAMP2A in the tumor and tumor-associated pericytes have been linked to temozolomide resistance and tumor progression. CMA activity directly depends on the levels of LAMP2A, a critical receptor for CMA substrate proteins at the lysosomal membrane. Chaperone-mediated autophagy (CMA) is a homeostatic process essential for the lysosomal degradation of a selected subset of the proteome.

Chaperone mediated autophagy assay