Chaperone-Mediated Autophagy Ablation in Pericytes Reveals New Glioblastoma Prognostic Markers and Efficient Treatment Against Tumor Progression

Autophagy mediated immune response regulation and drug resistance in cancer

Autophagy is a critical regulator of cellular homeostasis. The proteins involved in autophagy orchestrate the functions to strike the balance between cell survival and cell death in context-specific situations like aging, infections, inflammation and most importantly carcinogenesis. One of the major dead-locks in cancer treatment is the development of resistance to the available drugs (multi-drug resistance) as well as immune-suppressions in patients. Different studies over time have shown that autophagy is being involved in chemotherapy by working hand in hand with apoptosis or drug resistance through proliferative signals. Resistance to various drugs, such as, Cisplatin, Vincristine, Tamoxifen (TAM) occurs by epigenetic modifications, changed expression levels of microRNAs (miRNAs/miRs), and long non-coding RNAs (lncRNAs), which are regulated by the aberrant autophagy levels in lung, and breast cancers. More interestingly in the tumour microenvironment the immune suppressor cells also bring in autophagy in different pathway regulations either helping or opposing the whole carcinogenesis process. Macrophages, T cells, B cells, dendritic cells (DCs), neutrophils, and fibroblasts show involvement of autophagy in their differentiation and development in the tumor microenvironment (TME). Here, this extensive review for the first time tries to bring under a single canopy, several recent examples of autophagy-mediated immune regulations and autophagy-mediated epigenetically regulated drug resistance in different types of cancers.

Chaperone-mediated autophagy sustains pericyte stemness necessary for brain tissue homeostasis

INTRODUCTION

Pericytes (PCs) are mural cells exhibiting some mesenchymal stem cell (MSC) properties and contribute to tissue regeneration after injury. We have previously shown that glioblastoma cancer cells induce in PCs, a pathogenic upregulation of chaperone-mediated autophagy (CMA) which modulates immune functions and MSC-like properties to support tumor growth.

OBJECTIVES

The aim of the study was to interrogate the role of CMA-regulated MSC properties in PCs in the context of tissue repair during inflammation triggered by a demyelinating injury.

METHODS

Studies of RNA-seq were done PCs with (WT) and without (LAMP-2A KO) CMA. Cell characterization related to stemness, lineage and morphology was done in WT and KO PCs. Secretome analysis and cell differentiation assay using the supernatants from CMA-efficient and deficient PCs cultures was done in mesenchymal cells. Inflammatory response of brain cells was assessed with WT and KO PCs secretome. To corroborate in vitro results, CMA modulation in response to inflammation in PCs and tissue repair markers were measured in the lesion areas of a demyelination mouse model and correlated with the tissue reparation after intravenous PC administration. An inflammatory mediator was used to study effects on PC-CMA activity.

RESULTS

We found that inflammatory mediators such as IFNγ downregulate CMA in PCs, suppressing PC stemness and promoting a pro-inflammatory secretome. Restoration of PC CMA activity during inflammation maintains PC MSC properties and induces an MSC-like proteome which decreases inflammation and promotes tissue repair. We identified secreted proteins involved in regenerative and protective processes, and therefore, necessary to restore brain tissue homeostasis after inflammation induced by a demyelinating injury.

CONCLUSION

we show that manipulation of CMA activity in host PCs could be a useful therapeutical approach in the context of brain inflammation, which might be extended to other diseases where the pericyte has a key role in response to inflammation.

Periostin-mediated activation of NF-κB signaling promotes tumor progression and chemoresistance in glioblastoma

Glioblastoma (GBM) is the most aggressive form of diffuse glioma, characterized by high lethality. Temozolomide (TMZ)-based chemotherapy is a standard treatment for GBM, but development of chemoresistance poses a significant therapeutic challenge. Despite advances in understanding GBM biology, the mechanisms driving TMZ resistance remain unclear. Identifying vital molecular players involved in this resistance is crucial for developing new therapies. Our results indicated that periostin (POSTN) was significantly upregulated in GBM cell lines and patient samples, correlating with poorer clinical outcomes. POSTN overexpression enhanced GBM cell proliferation, migration, invasion, and chemoresistance, while lentiviral suppression of POSTN significantly reduced these behaviors. In vivo, bioluminescence imaging further confirmed the enhanced tumor growth associated with POSTN overexpression. Bioinformatics analysis was performed to explore the underlying molecular mechanism. The results revealed a strong correlation between POSTN and epithelial-mesenchymal transition (EMT) process and the tumor necrosis factor α (TNFα)-NF-κB signaling pathway. Moreover, exogenous POSTN silencing reduced IκB-kinase α (IKKα) phosphorylation, thereby decreasing NF-κB expression by limiting IκBα degradation. Collectively, our study demonstrated that POSTN-induced activation of NF-κB signaling and EMT processes promoted the malignancy and chemoresistance of GBM, suggesting that POSTN may serve as a reliable prognostic biomarker and potential therapeutic target for GBM.

The function of chaperones in the radioresistance of glioblastoma: a new insight into the current knowledge

Radiotherapy remains a cornerstone of brain tumor treatment; however, its effectiveness is frequently undermined by the development of radioresistance. This review highlights the pivotal role of molecular chaperones in promoting radioresistance and explores the potential to increase radioresistance in brain cancers, particularly glioblastoma (GBM). Among chaperones, heat shock proteins (HSPs), such as HSP70 and HSP90, have been identified as key contributors to radioresistance, acting through mechanisms that include the maintenance of protein homeostasis, enhancement of DNA repair processes, and protection of cancer stem cells. Specifically, HSP70 and HSP90 are crucial in stabilizing oncogenic proteins and preventing apoptosis, thus enabling tumor survival during radiotherapy. Also, HSP27 and GRP78 are involved in the radioresistance of brain tumors mainly by suppressing cell death and enhancing tumor stem cell propagation. Emerging evidence also suggests that targeting these chaperones, in combination with radiotherapy, can enhance tumor radiosensitivity, offering promising therapeutic strategies. Recent studies have revealed novel aspects of chaperone-mediated autophagy and interaction with non-coding RNAs, providing deeper insights into the molecular mechanisms underlying radioresistance. This review also addresses the potential of combining chaperone-targeted therapies, such as HSP90 inhibitors, with radiotherapy to overcome resistance. Ultimately, understanding these mechanisms may pave the way for innovative clinical applications and personalized therapeutic approaches in brain tumor treatment.

Research Advances in Chaperone-Mediated Autophagy (CMA) and CMA-Based Protein Degraders

Molecular mechanisms of chaperone-mediated autophagy (CMA) constitute essential regulatory elements in cellular homeostasis, encompassing protein quality control, metabolic regulation, cellular signaling cascades, and immunological functions. Perturbations in CMA functionality have been causally associated with various pathological conditions, including neurodegenerative pathologies and neoplastic diseases. Recent advances in targeted protein degradation (TPD) methodologies have demonstrated that engineered degraders incorporating KFERQ-like motifs can facilitate lysosomal translocation and subsequent proteolysis of noncanonical substrates, offering novel therapeutic interventions for both oncological and neurodegenerative disorders. This comprehensive review elucidates the molecular mechanisms, physiological significance, and pathological implications of CMA pathways. Additionally, it provides a critical analysis of contemporary developments in CMA-based degrader technologies, with particular emphasis on their structural determinants, mechanistic principles, and therapeutic applications. The discourse extends to current technical limitations in CMA investigation and identifies key obstacles that must be addressed to advance the development of CMA-targeting therapeutic agents.

Expression of Lumican and Osteopontin in Perivascular Areas of the Glioblastoma Peritumoral Niche and Its Value for Prognosis

Glioblastoma (GB) is one of the most aggressive and treatment-resistant cancers due to its complex tumor microenvironment (TME). We previously showed that GB progression is dependent on the aberrant induction of chaperone-mediated autophagy (CMA) in pericytes (PCs), which promotes TME immunosuppression through the PC secretome. The secretion of extracellular matrix (ECM) proteins with anti-tumor (Lumican) and pro-tumoral (Osteopontin, OPN) properties was shown to be dependent on the regulation of GB-induced CMA in PCs. As biomarkers are rarely studied in TME, in this work, we aimed to validate Lumican and OPN as prognostic markers in the perivascular areas of the peritumoral niche of a cohort of GB patients. Previously, we had validated their expression in GB xenografted mice presenting GB infiltration (OPN) or GB elimination (Lumican) dependent on competent or deficient CMA PCs, respectively. Then, patient sample classification by GB infiltration into the peritumoral brain parenchyma was related to GB-induced CMA in microvasculature PCs, analyzing the expression of the lysosomal receptor, LAMP-2A. Our results revealed a correlation between GB-induced CMA activity in peritumoral PCs and GB patients' outcomes, identifying three degrees of severity. The perivascular expression of both immune activation markers, Iba1 and CD68, was related to CMA-dependent PC immune function and determined as useful for efficient GB prognosis. Lumican expression was identified in perivascular areas of patients with less severe outcome and partially co-localizing with PCs presenting low CMA activity, while OPN was primarily found in perivascular areas of patients with poor outcome and partially co-localizing with PCs presenting high CMA activity. Importantly, we found sex differences in the incidence of middle-aged patients, being significantly higher in men but with worse prognosis in women. Our results confirmed that Lumican and OPN in perivascular areas of the GB peritumoral niche are effective predictive biomarkers for evaluating prognosis and monitoring possible therapeutic immune responses dependent on PCs in tumor progression.

Pericytes: jack-of-all-trades in cancer-related inflammation

Pericytes, recognized as mural cells, have long been described as components involved in blood vessel formation, playing a mere supporting role for endothelial cells (ECs). Emerging evidence strongly suggests their multifaceted roles in tissues and organs. Indeed, pericytes exhibit a remarkable ability to anticipate endothelial cell behavior and adapt their functions based on the specific cells they interact with. Pericytes can be activated by pro-inflammatory stimuli and crosstalk with immune cells, actively participating in their transmigration into blood vessels. Moreover, they can influence the immune response, often sustaining an immunosuppressive phenotype in most of the cancer types studied. In this review, we concentrate on the intricate crosstalk between pericytes and immune cells in cancer, highlighting the primary evidence regarding pericyte involvement in primary tumor mass dynamics, their contributions to tumor reprogramming for invasion and migration of malignant cells, and their role in the formation of pre-metastatic niches. Finally, we explored recent and emerging pharmacological approaches aimed at vascular normalization, including novel strategies to enhance the efficacy of immunotherapy through combined use with anti-angiogenic drugs.

Pericytes Are Immunoregulatory Cells in Glioma Genesis and Progression

Vascular co-option is a consequence of the direct interaction between perivascular cells, known as pericytes (PCs), and glioblastoma multiforme (GBM) cells (GBMcs). This process is essential for inducing changes in the pericytes' anti-tumoral and immunoreactive phenotypes. Starting from the initial stages of carcinogenesis in GBM, PCs conditioned by GBMcs undergo proliferation, acquire a pro-tumoral and immunosuppressive phenotype by expressing and secreting immunosuppressive molecules, and significantly hinder the activation of T cells, thereby facilitating tumor growth. Inhibiting the pericyte (PC) conditioning mechanisms in the GBM tumor microenvironment (TME) results in immunological activation and tumor disappearance. This underscores the pivotal role of PCs as a key cell in the TME, responsible for tumor-induced immunosuppression and enabling GBM cells to evade the immune system. Other cells within the TME, such as tumor-associated macrophages (TAMs) and microglia, have also been identified as contributors to this immunomodulation. In this paper, we will review the role of these three cell types in the immunosuppressive properties of the TME. Our conclusion is that the cellular heterogeneity of immunocompetent cells within the TME may lead to the misinterpretation of cellular lineage identification due to different reactive stages and the identification of PCs as TAMs. Consequently, novel therapies could be developed to disrupt GBM-PC interactions and/or PC conditioning through vascular co-option, thereby exposing GBMcs to the immune system.

Role of autophagy in angiogenic potential of vascular pericytes

The vasculature system is composed of a multiplicity of juxtaposed cells to generate a functional biological barrier between the blood and tissues. On the luminal surface of blood vessels, endothelial cells (ECs) are in close contact with circulating cells while supporting basal lamina and pericytes wrap the abluminal surface. Thus, the reciprocal interaction of pericytes with ECs is a vital element in the physiological activity of the vascular system. Several reports have indicated that the occurrence of pericyte dysfunction under ischemic and degenerative conditions results in varied micro and macro-vascular complications. Emerging evidence points to the fact that autophagy, a conserved self-digestive cell machinery, can regulate the activity of several cells like pericytes in response to various stresses and pathological conditions. Here, we aim to highlight the role of autophagic response in pericyte activity and angiogenesis potential following different pathological conditions.

The Role of Chaperone-Mediated Autophagy in Tissue Homeostasis and Disease Pathogenesis

Chaperone-mediated autophagy (CMA) is a selective proteolytic pathway in the lysosomes. Proteins are recognized one by one through the detection of a KFERQ motif or, at least, a KFERQ-like motif, by a heat shock cognate protein 70 (Hsc70), a molecular chaperone. CMA substrates are recognized and delivered to a lysosomal CMA receptor, lysosome-associated membrane protein 2A (LAMP-2A), the only limiting component of this pathway, and transported to the lysosomal lumen with the help of another resident chaperone HSp90. Since approximately 75% of proteins are reported to have canonical, phosphorylation-generated, or acetylation-generated KFERQ motifs, CMA maintains intracellular protein homeostasis and regulates specific functions in the cells in different tissues. CMA also regulates physiologic functions in different organs, and is then implicated in disease pathogenesis related to aging, cancer, and the central nervous and immune systems. In this minireview, we have summarized the most important findings on the role of CMA in tissue homeostasis and disease pathogenesis, updating the recent advances for this Special Issue.

Chaperone-mediated autophagy: Molecular mechanisms, biological functions, and diseases

Chaperone-mediated autophagy (CMA) is a lysosomal degradation pathway that eliminates substrate proteins through heat-shock cognate protein 70 recognition and lysosome-associated membrane protein type 2A-assisted translocation. It is distinct from macroautophagy and microautophagy. In recent years, the regulatory mechanisms of CMA have been gradually enriched, including the newly discovered NRF2 and p38-TFEB signaling, as positive and negative regulatory pathways of CMA, respectively. Normal CMA activity is involved in the regulation of metabolism, aging, immunity, cell cycle, and other physiological processes, while CMA dysfunction may be involved in the occurrence of neurodegenerative disorders, tumors, intestinal disorders, atherosclerosis, and so on, which provides potential targets for the treatment and prediction of related diseases. This article describes the general process of CMA and its role in physiological activities and summarizes the connection between CMA and macroautophagy. In addition, human diseases that concern the dysfunction or protective role of CMA are discussed. Our review deepens the understanding of the mechanisms and physiological functions of CMA and provides a summary of past CMA research and a vision of future directions.

Pericyte-Glioblastoma Cell Interaction: A Key Target to Prevent Glioblastoma Progression

Multiple biological processes rely on direct intercellular interactions to regulate cell proliferation and migration in embryonic development and cancer processes. Tumor development and growth depends on close interactions between cancer cells and cells in the tumor microenvironment. During embryonic development, morphogenetic signals and direct cell contacts control cell proliferation, polarity, and morphogenesis. Cancer cells communicate with cells in the tumor niche through molecular signals and intercellular contacts, thereby modifying the vascular architecture and antitumor surveillance processes and consequently enabling tumor growth and survival. While looking for cell-to-cell signaling mechanisms that are common to both brain development and cancer progression, we have studied the infiltration process in glioblastoma multiforme (GBM), which is the most malignant primary brain tumor and with the worst prognosis. Cell-to-cell contacts, by means of filopodia-like structures, between GBM cells and brain pericytes (PCs) are necessary for adequate cell signaling during cancer infiltration; similarly, contacts between embryonic regions, via cytonemes, are required for embryo regionalization and development. This GBM-PC interaction provokes two important changes in the physiological function of these perivascular cells, namely, (i) vascular co-option with changes in cell contractility and vascular malformation, and (ii) changes in the PC transcriptome, modifying the microvesicles and protein secretome, which leads to the development of an immunosuppressive phenotype that promotes tumor immune tolerance. Moreover, the GTPase Cdc42 regulates cell polarity across organisms, from yeast to humans, playing a central role in GBM cell-PC interaction and maintaining vascular co-option. As such, a review of the molecular and cellular mechanisms underlying the development and maintenance of the physical interactions between cancer cells and PCs is of particular interest.

The Role of Pericytes in Regulation of Innate and Adaptive Immunity

Pericytes are perivascular multipotent cells wrapping microvascular capillaries, where they support vasculature functioning, participate in tissue regeneration, and regulate blood flow. However, recent evidence suggests that in addition to traditionally credited structural function, pericytes also manifest immune properties. In this review, we summarise recent data regarding pericytes' response to different pro-inflammatory stimuli and their involvement in innate immune responses through expression of pattern-recognition receptors. Moreover, pericytes express various adhesion molecules, thus regulating trafficking of immune cells across vessel walls. Additionally, the role of pericytes in modulation of adaptive immunity is discussed. Finally, recent reports have suggested that the interaction with cancer cells evokes immunosuppression function in pericytes, thus facilitating immune evasion and facilitating cancer proliferation and metastasis. However, such complex and multi-faceted cross-talks of pericytes with immune cells also suggest a number of potential pericyte-based therapeutic methods and techniques for cancer immunotherapy and treatment of autoimmune and auto-inflammatory disorders.

Chaperone-Mediated Autophagy in Pericytes: A Key Target for the Development of New Treatments against Glioblastoma Progression

Glioblastoma (GB) cells physically interact with peritumoral pericytes (PCs) present in the brain microvasculature. These interactions facilitate tumor cells to aberrantly increase and benefit from chaperone-mediated autophagy (CMA) in the PC. GB-induced CMA leads to major changes in PC immunomodulatory phenotypes, which, in turn, support cancer progression. In this review, we focus on the consequences of the GB-induced up-regulation of CMA activity in PCs and evaluate how manipulation of this process could offer new strategies to fight glioblastoma, increasing the availability of treatments for this cancer that escapes conventional therapies. We finally discuss the use of modified PCs unable to increase CMA in response to GB as a cell therapy alternative to minimize undesired off-target effects associated with a generalized CMA inhibition.

Role of Chaperone-Mediated Autophagy in Ageing Biology and Rejuvenation of Stem Cells

What lies at the basis of the mechanisms that regulate the maintenance and self-renewal of pluripotent stem cells is still an open question. The control of stemness derives from a fine regulation between transcriptional and metabolic factors. In the last years, an emerging topic has concerned the involvement of Chaperone-Mediated Autophagy (CMA) as a key mechanism in stem cell pluripotency control acting as a bridge between epigenetic, transcriptional and differentiation regulation. This review aims to clarify this new and not yet well-explored horizon discussing the recent studies regarding the CMA impact on embryonic, mesenchymal, and haematopoietic stem cells. The review will discuss how CMA influences embryonic stem cell activity promoting self-renewal or differentiation, its involvement in maintaining haematopoietic stem cell function by increasing their functionality during the normal ageing process and its effects on mesenchymal stem cells, in which modulation of CMA regulates immunosuppressive and differentiation properties. Finally, the importance of these new discoveries and their relevance for regenerative medicine applications, from transplantation to cell rejuvenation, will be addressed.