Combined autophagy and proteasome inhibition: a phase 1 trial of hydroxychloroquine and bortezomib in patients with relapsed/refractory myeloma

Impact of proteostasis workload on sensitivity to proteasome inhibitors in multiple myeloma

Genomic alterations and enormous monoclonal immunoglobulin production cause multiple myeloma to heavily depend on proteostasis mechanisms, including protein folding and degradation. These findings support the use of proteasome inhibitors for treating multiple myeloma and mantle cell lymphoma. Myeloma treatment has evolved, especially with the availability of new drugs, such as proteasome inhibitors, into therapeutic strategies for both frontline and relapsed/refractory disease settings. However, proteasome inhibitors are generally not effective enough to cure most patients. Natural resistance and eventual acquired resistance led to relapsed/refractory disease and poor prognosis. Advances in the understanding of cellular proteostasis and the development of innovative drugs that also target other proteostasis network components offer opportunities to exploit the intrinsic vulnerability of myeloma cells. This review outlines recent findings on the molecular mechanisms regulating cellular proteostasis pathways, as well as resistance, sensitivity, and escape strategies developed against proteasome inhibitors and provides a rationale and examples for novel combinations of proteasome inhibitors with FDA-approved drugs and investigational drugs targeting the NRF1 (NFE2L1)-mediated proteasome bounce-back response, redox homeostasis, heat shock response, unfolding protein response, autophagy, and VCP/p97 to increase proteotoxic stress, which can improve the efficacy of antimyeloma therapy based on proteasome inhibitors.

Autophagy in cancer and protein conformational disorders

Autophagy is a catabolic process by which cells maintain cellular homeostasis through the degradation of dysfunctional cytoplasmic components, such as toxic misfolded proteins and damaged organelles, within the lysosome. It is a multistep process that is tightly regulated by nutrient, energy, and stress-sensing mechanisms. Autophagy plays a pivotal role in various biological processes, including protein and organelle quality control, defense against pathogen infections, cell metabolism, and immune surveillance. As a result, autophagy dysfunction is linked to a variety of pathological conditions. The role of autophagy in cancer is complex and dynamic. Depending on the context, autophagy can have both tumor-suppressive and pro-tumorigenic effects. In contrast, its role is more clearly defined in protein conformational disorders, where autophagy serves as a mechanism to reduce toxic protein aggregation, thereby improving cellular homeostasis. Because autophagy-based therapies hold promising potential for the treatment of cancer and protein conformational disorders, this review will highlight the latest findings and advancements in these areas.

A novel indirubin- 3-monoxime derivative I3MV- 8b exhibits remarkable cytotoxicity against multiple myeloma by targeting TRIM28

INTRODUCTION

Maintaining protein homeostasis is vital for multiple myeloma (MM) cell survival. Indirubin- 3-monoxime (I3MO), a potential MM therapeutic, inhibits proteasome activity, while histone deacetylase 6 (HDAC6) regulates autophagy. We developed I3MV- 8b, an I3MO derivative, integrating an HDAC6 inhibitor moiety to enhance dual inhibition of proteasome and autophagy pathways.

METHODS

The anti-MM effects of I3MV- 8b were tested in vitro and in vivo. To identify downstream targets, RNA-seq and dual-luciferase reporter assays were performed. Additionally, ChIP-seq and IP-MS techniques were employed to elucidate the underlying molecular mechanism.

RESULTS

I3MV- 8b significantly suppressed MM cell proliferation and induced apoptosis. Combined with proteasome inhibitors, I3MV- 8b enhanced cytotoxicity by concurrently inhibiting proteasome and autophagy pathways. It reduced TRIM28 transcription, correlating with lower expression of proteasome subunits and autophagy-related genes. ChIP-seq revealed that TRIM28 binds to proteasome gene promoters, and its knockdown decreased proteasome subunit expression and activity. TRIM28 knockdown also impaired autophagosome formation. IP-MS and Co-IP assays showed TRIM28 interacted with 14-3 - 3ζ, a negative regulator of autophagy, promoting its ubiquitination and degradation. This interaction reduced autophagy regulation, further sensitizing cells to treatment.

CONCLUSIONS

I3MV- 8b offers a novel dual inhibition strategy targeting proteasome and autophagy, presenting a promising therapeutic option for MM.

The role of autophagy in cancer: from molecular mechanism to therapeutic window

Autophagy is a cellular degradation process that plays a crucial role in maintaining metabolic homeostasis under conditions of stress or nutrient deprivation. This process involves sequestering, breaking down, and recycling intracellular components such as proteins, organelles, and cytoplasmic materials. Autophagy also serves as a mechanism for eliminating pathogens and engulfing apoptotic cells. In the absence of stress, baseline autophagy activity is essential for degrading damaged cellular components and recycling nutrients to maintain cellular vitality. The relationship between autophagy and cancer is well-established; however, the biphasic nature of autophagy, acting as either a tumor growth inhibitor or promoter, has raised concerns regarding the regulation of tumorigenesis without inadvertently activating harmful aspects of autophagy. Consequently, elucidating the mechanisms by which autophagy contributes to cancer pathogenesis and the factors determining its pro- or anti-tumor effects is vital for devising effective therapeutic strategies. Furthermore, precision medicine approaches that tailor interventions to individual patients may enhance the efficacy of autophagy-related cancer treatments. To this end, interventions aimed at modulating the fate of tumor cells by controlling or inducing autophagy substrates necessitate meticulous monitoring of these mediators' functions within the tumor microenvironment to make informed decisions regarding their activation or inactivation. This review provides an updated perspective on the roles of autophagy in cancer, and discusses the potential challenges associated with autophagy-related cancer treatment. The article also highlights currently available strategies and identifies questions that require further investigation in the future.

Targeting autophagy in platinum-sensitive relapsed ovarian cancer: randomized phase II trial of hydroxychloroquine with chemotherapy with biomarker correlation

BACKGROUND

Autophagy activation contributes to chemotherapy resistance in several cancers, including ovarian cancer. Hydroxychloroquine (HCQ) is an autophagy inhibitor inhibiting the fusion of the autophagosome with the lysosome and has been repurposed as an anti-cancer agent. In this randomized phase II study, we used HCQ in combination with standard chemotherapy in platinum sensitive relapsed ovarian cancer (PSROC) patients.

METHODS

Patients were randomized in a 1:1 ratio to receive standard chemotherapy (carboplatin with paclitaxel/gemcitabine) with or without HCQ. Those randomized to receive HCQ received additional HCQ 200mg orally twice daily. The primary endpoint was the overall response rate (ORR). Other endpoints included survival outcomes, changes in autophagy biomarkers, toxicity, and quality of life.

RESULTS

A total of 59 patients were enrolled- chemotherapy + HCQ (N = 28), chemotherapy alone (N = 31), and 56 were evaluable ( received ≥ 3 cycles treatment). The ORR was not superior with the addition of HCQ [85% (22/26) in the experimental arm as compared to 80% (24/30)  in the control arm, chi-square test, P = 0.65]. The median progression-free survival was 12 (95% CI, 9.75-14.24) months for the experimental arm and 11 (95% CI, 5.25-16.74) months for the control arm (P = 0.56) , and the median overall survival was 16 (95% CI, 8.54-23.45) months vs. 21 (95% CI, 11.70-30.59 ) months (P = 0.49) respectively. HCQ was well tolerated, with no excess adverse events [21 (75%) in the experimental arm vs. 22 (71%) in the control arm]. There were no substantial differences in the reduction of autophagy biomarker levels and QOL between the control and experimental arms.

CONCLUSION

Adding HCQ to chemotherapy failed to improve response rates or survival in patients with PSROC. Conducting biomarker-stratified clinical trials might show the potential benefit of HCQ. Trial registration number (TRN): The trial was registered in the Clinical Trial Registry of India ( www.ctri.nic.in ; CTRI/2020/06/025790) on 17th June 2020.

Combined Proteasome and Autophagy Inhibition in Relapsed/Refractory Multiple Myeloma-A Phase I Trial of Hydroxychloroquine, Carfilzomib, and Dexamethasone

Multiple myeloma is characterized by malignant cells which produce high amounts of monoclonal immunoglobulin. Myeloma cells are, therefore, dependent on effective protein degradation. Proteasomal protein degradation is targeted by proteasome inhibitors in routine care. Autophagic protein degradation is currently not targeted in myeloma treatment. This Phase I trial showed that the combination of the proteasome inhibitor carfilzomib and the autophagy inhibitor hydroxychloroquine was well tolerated in patients with relapsed/refractory multiple myeloma. Adverse events were mostly Grades 1 and 2. An overall response rate of 44% indicates a meaningful clinical efficacy of this combination. Trial Registration: The study was registered at clinicaltrials.gov # NCT04163107.

Caspase 3 and caspase 7 promote cytoprotective autophagy and the DNA damage response during non-lethal stress conditions in human breast cancer cells

Cell stress adaptation plays a key role in normal development and in various diseases including cancer. Caspases are activated in response to cell stress, and growing evidence supports their function in non-apoptotic cellular processes. A role for effector caspases in promoting stress-induced cytoprotective autophagy was demonstrated in Drosophila, but has not been explored in the context of human cells. We found a functionally conserved role for effector caspase 3 (CASP3) and caspase 7 (CASP7) in promoting starvation or proteasome inhibition-induced cytoprotective autophagy in human breast cancer cells. The loss of CASP3 and CASP7 resulted in an increase in PARP1 cleavage, reduction in LC3B and ATG7 transcript levels, and a reduction in H2AX phosphorylation, consistent with a block in autophagy and DNA damage-induced stress response pathways. Surprisingly, in non-lethal cell stress conditions, CASP7 underwent non-canonical processing at two calpain cleavage sites flanking a PARP1 exosite, resulting in stable CASP7-p29/p30 fragments. Expression of CASP7-p29/p30 fragment(s) could rescue H2AX phosphorylation in the CASP3 and CASP7 double knockout background. Strikingly, yet consistent with these phenotypes, the loss of CASP3 and CASP7 exhibited synthetic lethality with BRCA1 loss. These findings support a role for human caspases in stress adaptation through PARP1 modulation and reveal new therapeutic avenues for investigation.

Phase I trial of hydroxychloroquine to enhance palbociclib and letrozole efficacy in ER+/HER2- breast cancer

Endocrine therapy with CDK4/6 inhibitors is standard for estrogen receptor-positive, HER2-negative metastatic breast cancer (ER+/HER2- MBC), yet clinical resistance develops. Previously, we demonstrated that low doses of palbociclib activate autophagy, reversing initial G1 cell cycle arrest, while high concentrations induce off-target senescence. The autophagy inhibitor hydroxychloroquine (HCQ) induced on-target senescence at lower palbociclib doses. We conducted a phase I trial (NCT03774472 registered in ClinicalTrials.gov on 8/20/2018) of HCQ (400, 600, 800 mg/day) with palbociclib (75 mg/day continuous) and letrozole, using a 3 + 3 design. Primary objectives included safety, tolerability, and determining the recommended phase 2 dose (RP2D) of HCQ. Secondary objectives included tumor response and biomarker analysis. Fourteen ER+/HER2- MBC patients were evaluable [400 mg (n = 4), 600 mg (n = 4), 800 mg (n = 6)]. Grade 3 adverse events (AEs) included hematological (3 at 800 mg), skin rash (2 at 600 mg), and anorexia (1 at 400 mg), with no serious AEs. The best responses were partial (2), stable (11), and progression (1). Tumor reductions ranged from 11% to 30%, with one 55% increase. The two partial responders sustained tumor size reductions of 30% to 55% over an extended treatment period, lasting nearly 300 days. Biomarker analysis in responders demonstrated significant decreases in Ki67, Rb, and nuclear cyclin E levels and increases in autophagy markers p62 and LAMP1, suggesting a correlation between these biomarkers and treatment response. This phase I study demonstrated that HCQ is safe and well-tolerated and the RP2D was established at 800 mg/day with continuous low-dose palbociclib (75 mg/day) and letrozole (2.5 mg/day). These findings suggest that adding HCQ could potentially enhance the efficacy of low-dose palbociclib and standard letrozole therapy, pending verification in larger randomized studies.

Prognostic Value of PSMB5 and Correlations with LC3II and Reactive Oxygen Species Levels in the Bone Marrow Mononuclear Cells of Bortezomib-Resistant Multiple Myeloma Patients

Proteasome inhibitors (PIs) constitute the most common type of induction treatment for multiple myeloma. Interactions between the proteasome, autophagy, and reactive oxygen species (ROS) have been shown in the past, thus emphasizing the need for a better understanding of the underlying pathophysiology. For this study, bone marrow mononuclear cells from 110 myeloma patients were collected at different disease stages. PSMB5 and LC3I/II protein levels were determined using Western blot, proteasome proteolytic activity (PPA) with spectrofluorometry, and ROS with flow cytometry. PSMB5 accumulation was found to diminish after PI treatment (p-value = 0.014), and the same pattern was observed in PPA (p-value < 0.001). Conversely, LC3II protein levels were elevated at both remission and relapse compared to baseline levels (p-value = 0.041). Patients with a baseline PSMB5 accumulation lower than 1.06 units had longer disease-free survival compared to those with values above 1.06 units (12.0 ± 6.7 vs. 36 ± 12.1 months; p-value < 0.001). Median ROS levels in plasma cells were significantly higher at relapse compared to both baseline and remission levels (p-value < 0.001), implying poor prognosis. Overall, post-treatment PSMB5 reduction could indicate a shift from proteasomal to autophagic degradation as a main proteostatic mechanism, thus explaining resistance. The elevated oxidative stress in PI-treated patients could possibly serve as an additional compensatory mechanism.

Autophagy in cancer development, immune evasion, and drug resistance

Macroautophagy/autophagy is a highly conserved evolutionary mechanism involving lysosomes for the degradation of cytoplasmic components including organelles. The constitutive, basal level of autophagy is fundamental for preserving cellular homeostasis; however, alterations in autophagy can cause disease pathogenesis, including cancer. The role of autophagy in cancer is particularly complicated, since this process acts both as a tumor suppressor in precancerous stages but facilitates tumor progression during carcinogenesis and later stages of cancer progression. This shift between anti-tumor and pro-tumor roles may be influenced by genetic and environmental factors modulating key pathways such as those involving autophagy-related proteins, the PI3K-AKT-MTOR axis, and AMPK, which often show dysregulation in tumors. Autophagy regulates various cellular functions, including metabolism of glucose, glutamine, and lipids, cell proliferation, metastasis, and several types of cell death (apoptosis, ferroptosis, necroptosis and immunogenic cell death). These multifaceted roles demonstrate the potential of autophagy to affect DNA damage repair, cell death pathways, proliferation and survival, which are critical in determining cancer cells' response to chemotherapy. Therefore, targeting autophagy pathways presents a promising strategy to combat chemoresistance, as one of the major reasons for the failure in cancer patient treatment. Furthermore, autophagy modulates immune evasion and the function of immune cells such as T cells and dendritic cells, influencing the tumor microenvironment and cancer's biological behavior. However, the therapeutic targeting of autophagy is complex due to its dual role in promoting survival and inducing cell death in cancer cells, highlighting the need for strategies that consider both the beneficial and detrimental effects of autophagy modulation in cancer therapy. Hence, both inducers and inhibitors of autophagy have been introduced for the treatment of cancer. This review emphasizes the intricate interplay between autophagy, tumor biology, and immune responses, offering insights into potential therapeutic approaches that deploy autophagy in the cancer suppression.

Navigating therapeutic prospects by modulating autophagy in colorectal cancer

Colorectal cancer (CRC) remains a leading cause of death globally despite the improvements in cancer treatment. Autophagy is an evolutionarily conserved lysosomal-dependent degradation pathway that is critical in maintaining cellular homeostasis. However, in cancer, autophagy may have conflicting functions in preventing early tumour formation versus the maintenance of advanced-stage tumours. Defective autophagy has a broad and dynamic effect not just on cancer cells, but also on the tumour microenvironment which influences tumour progression and response to treatment. To add to the layer of complexity, somatic mutations in CRC including tumour protein p53 (TP53), v-raf murine sarcoma viral oncogene homolog B1 (BRAF), Kirsten rat sarcoma viral oncogene homolog (KRAS), and phosphatase and tensin homolog (PTEN) can render chemoresistance by promoting a pro-survival advantage through autophagy. Recent studies have also reported autophagy-related cell deaths that are distinct from classical autophagy by employing parts of the autophagic machinery, which impacts strategies for autophagy regulation in cancer therapy. This review discusses the molecular processes of autophagy in the evolution of CRC and its role in the tumour microenvironment, as well as prospective therapeutic methods based on autophagy suppression or promotion. It also highlights clinical trials using autophagy modulators for treating CRC, underscoring the importance of autophagy regulation in CRC therapy.

Amantadine against glioma via ROS-mediated apoptosis and autophagy arrest

Glioma is a common primary nervous system malignant tumor with poor overall cure rate and low survival rate, yet successful treatment still remains a challenge. Here, we demonstrated that amantadine (AMT) exhibits the powerful anti-glioma effect by promoting apoptosis and autophagy in vivo and in vitro. Mechanistically, amantadine induces a large amount of reactive oxygen species (ROS) accumulation in glioma cells, and then triggers apoptosis by destroying mitochondria. In addition, amantadine induces the initiation of autophagy and inhibits the fusion of autophagosome and lysosome, consequently performing an anti-glioma role. Taken together, our findings suggest that amantadine could be a promising anti-glioma drug that inhibits glioma cells by inducing apoptosis and autophagy, which may provide a novel potential treatment option for patients.

Ubiquitination regulates autophagy in cancer: simple modifications, promising targets

Autophagy is an important lysosomal degradation process that digests and recycles bio-molecules, protein or lipid aggregates, organelles, and invaded pathogens. Autophagy plays crucial roles in regulation of metabolic and oxidative stress and multiple pathological processes. In cancer, the role of autophagy is dual and paradoxical. Ubiquitination has been identified as a key regulator of autophagy that can influence various steps in the autophagic process, with autophagy-related proteins being targeted for ubiquitination, thus impacting cancer progression and the effectiveness of therapeutic interventions. This review will concentrate on mechanisms underlying autophagy, ubiquitination, and their interactions in cancer, as well as explore the use of drugs that target the ubiquitin-proteasome system (UPS) and ubiquitination process in autophagy as part of cancer therapy.

Understanding the autophagic functions in cancer stem cell maintenance and therapy resistance

Complex tumour ecosystem comprising tumour cells and its associated tumour microenvironment (TME) constantly influence the tumoural behaviour and ultimately impact therapy failure, disease progression, recurrence and poor overall survival of patients. Crosstalk between tumour cells and TME amplifies the complexity by creating metabolic changes such as hypoxic environment and nutrient fluctuations. These changes in TME initiate stem cell-like programmes in cancer cells, contribute to tumoural heterogeneity and increase tumour robustness. Recent studies demonstrate the multifaceted role of autophagy in promoting fibroblast production, stemness, cancer cell survival during longer periods of dormancy, eventual growth of metastatic disease and disease resistance. Recent ongoing studies examine autophagy/mitophagy as a powerful survival strategy in response to environmental stress including nutrient deprivation, hypoxia and environmental stress in TME. It prevents irreversible senescence, promotes dormant stem-like state, induces epithelial-mesenchymal transition and increases migratory and invasive potential of tumour cells. The present review discusses various theories and mechanisms behind the autophagy-dependent induction of cancer stem cell (CSC) phenotype. Given the role of autophagic functions in CSC aggressiveness and therapeutic resistance, various mechanisms and studies based on suppressing cellular plasticity by blocking autophagy as a powerful therapeutic strategy to kill tumour cells are discussed.

Docosahexaenoic acid enhances the treatment efficacy for castration-resistant prostate cancer by inhibiting autophagy through Atg4B inhibition

Autophagy induction in cancer is involved in cancer progression and the acquisition of resistance to anticancer agents. Therefore, autophagy is considered a potential therapeutic target in cancer therapy. In this study, we found that long-chain fatty acids (LCFAs) have inhibitory effects on Atg4B, which is essential for autophagosome formation, through screening based on the pharmacophore of 21f, a recently developed Atg4B inhibitor. Among these fatty acids, docosahexaenoic acid (DHA), a polyunsaturated fatty acid, exhibited the most potent Atg4B inhibitory activity. DHA inhibited autophagy induced by androgen receptor signaling inhibitors (ARSI) in LNCaP and 22Rv1 prostate cancer cells and significantly increased apoptotic cell death. Furthermore, we investigated the effect of DHA on resistance to ARSI by establishing darolutamide-resistant prostate cancer 22Rv1 (22Rv1/Dar) cells, which had developed resistance to darolutamide, a novel ARSI. At baseline, 22Rv1/Dar cells showed a higher autophagy level than parental 22Rv1 cells. DHA significantly suppressed Dar-induced autophagy and sensitized 22Rv1/Dar cells by inducing apoptotic cell death through mitochondrial dysfunction. These results suggest that DHA supplementation may improve prostate cancer therapy with ARSI.

UNC13B regulates the sensitivity of Wilms' tumor cells to doxorubicin by modulating lysosomes

Wilms' tumor is a malignant neoplasm where current medical advancements have significantly improved survival rates; however, challenges persist such as the resistance of the tumor to chemotherapy drugs like doxorubicin. This necessitates higher dosages, leading to decreased sensitivity. However, using high doses of doxorubicin can have late effects on the heart. Unc-13 homolog B (UNC13B) may be involved in the drug resistance in several tumors, yet its role in modulating drug sensitivity in Wilms' tumor remains unexplored. UNC13B levels were quantified using reverse transcription-qPCR and Western blotting. The half-maximal inhibitory concentration for doxorubicin, vincristine, and actinomycin-D was determined using CCK-8 assays. Cell cycle and apoptosis were analyzed using flow cytometry, and lysosomal changes were observed using Lyso-Tracker staining. The present study initially evaluated UNC13B expression levels in the Wilms' tumor 17.94 cell line. Additionally, through short hairpin RNA-mediated knockdown, changes in doxorubicin sensitivity in 17.94 Wilms' tumor cells were assessed. Concurrently, preliminary investigations into the role of UNC13B in regulating lysosomes was performed, revealing a significant positive association between UNC13B levels and lysosome formation in the 17.94 cell line. Lysosomes likely serve a role in the sensitivity of Wilms' tumor cell lines to drugs. Elevated UNC13B expression was observed in the 17.94 Wilms' tumor cell line compared to normal kidney cells. UNC13B knockdown also resulted in increased apoptosis levels upon doxorubicin treatment. Immunofluorescence revealed UNC13B localization within cellular vesicles, and its knockdown significantly decreased lysosome levels. Overall, the findings of the present study demonstrate that UNC13B regulates the sensitivity of the Wilms' tumor 17.94 cell line to doxorubicin by modulating lysosome formation within cells. The results suggest that UNC13B is likely an enriched target involved in lysosomal regulation in certain tumors, offering a new approach for optimizing chemotherapy in Wilms' tumor and other cancers with high UNC13B expression.

Different Strategies to Overcome Resistance to Proteasome Inhibitors-A Summary 20 Years after Their Introduction

Proteasome inhibitors (PIs), bortezomib, carfilzomib, and ixazomib, are the first-line treatment for multiple myeloma (MM). They inhibit cytosolic protein degradation in cells, which leads to the accumulation of misfolded and malfunctioned proteins in the cytosol and endoplasmic reticulum, resulting in cell death. Despite being a breakthrough in MM therapy, malignant cells develop resistance to PIs via different mechanisms. Understanding these mechanisms drives research toward new anticancer agents to overcome PI resistance. In this review, we summarize the mechanism of action of PIs and how MM cells adapt to these drugs to develop resistance. Finally, we explore these mechanisms to present strategies to interfere with PI resistance. The strategies include new inhibitors of the ubiquitin-proteasome system, drug efflux inhibitors, autophagy disruption, targeting stress response mechanisms, affecting survival and cell cycle regulators, bone marrow microenvironment modulation, and immunotherapy. We list potential pharmacological targets examined in in vitro, in vivo, and clinical studies. Some of these strategies have already provided clinicians with new anti-MM medications, such as panobinostat and selinexor. We hope that further exploration of the subject will broaden the range of therapeutic options and improve patient outcomes.

Autophagy in glioblastoma: A mechanistic perspective

Glioblastoma (GBM) is one of the most lethal malignancies in humans. Even after surgical resection and aggressive radio- or chemotherapies, patients with GBM can survive for less than 14 months. Extreme inter-tumor and intra-tumor heterogeneity of GBM poses a challenge for resolving recalcitrant GBM pathophysiology. GBM tumor microenvironment (TME) exhibits diverse heterogeneity in cellular composition and processes contributing to tumor progression and therapeutic resistance. Autophagy is such a cellular process; that demonstrates a cell-specific and TME context-dependent role in GBM progression, leading to either the promotion or suppression of GBM progression. Autophagy can regulate GBM cell function directly via regulation of survival, migration, and invasion, or indirectly by affecting GBM TME composition such as immune cell population, tumor metabolism, and glioma stem cells. This review comprehensively investigates the role of autophagy in GBM pathophysiology.

Role of Autophagy and AMPK in Cancer Stem Cells: Therapeutic Opportunities and Obstacles in Cancer

Cancer stem cells represent a resilient subset within the tumor microenvironment capable of differentiation, regeneration, and resistance to chemotherapeutic agents, often using dormancy as a shield. Their unique properties, including drug resistance and metastatic potential, pose challenges for effective targeting. These cells exploit certain metabolic processes for their maintenance and survival. One of these processes is autophagy, which generally helps in energy homeostasis but when hijacked by CSCs can help maintain their stemness. Thus, it is often referred as an Achilles heel in CSCs, as certain cancers tend to depend on autophagy for survival. Autophagy, while crucial for maintaining stemness in cancer stem cells (CSCs), can also serve as a vulnerability in certain contexts, making it a complex target for therapy. Regulators of autophagy like AMPK (5' adenosine monophosphate-activated protein kinase) also play a crucial role in maintaining CSCs stemness by helping CSCs in metabolic reprogramming in harsh environments. The purpose of this review is to elucidate the interplay between autophagy and AMPK in CSCs, highlighting the challenges in targeting autophagy and discussing therapeutic strategies to overcome these limitations. This review focuses on previous research on autophagy and its regulators in cancer biology, particularly in CSCs, addresses the remaining unanswered questions, and potential targets for therapy are also brought to attention.

A comprehensive review of the PTEN/PI3K/Akt axis in multiple myeloma: From molecular interactions to potential therapeutic targets

Phosphatase and tensin homolog (PTEN), phosphatidylinositol 3-kinase (PI3K), and protein kinase B (Akt) signaling pathways contribute to the development of several cancers, including multiple myeloma (MM). PTEN is a tumor suppressor that influences the PI3K/Akt/mTOR pathway, which in turn impacts vital cellular processes like growth, survival, and treatment resistance. The current study aims to present the role of PTEN and PI3K/Akt/mTOR signaling in the development of MM and its response to treatment. In addition, the molecular interactions in MM that underpin the PI3K/Akt/mTOR pathway and address potential implications for the development of successful treatment plans are also discussed in detail. We investigate their relationship to both upstream and downstream regulators, highlighting new developments in combined therapies that target the PTEN/PI3K/Akt axis to overcome drug resistance, including the use of PI3K and mitogen-activated protein kinase (MAPK) inhibitors. We also emphasize that PTEN/PI3K/Akt pathway elements may be used in MM diagnosis, prognosis, and therapeutic targets.

VMP1: a multifaceted regulator of cellular homeostasis with implications in disease pathology

Vacuole membrane protein 1 (VMP1) is an integral membrane protein that plays a pivotal role in cellular processes, particularly in the regulation of autophagy. Autophagy, a self-degradative mechanism, is essential for maintaining cellular homeostasis by degradation and recycling damaged organelles and proteins. VMP1 involved in the autophagic processes include the formation of autophagosomes and the subsequent fusion with lysosomes. Moreover, VMP1 modulates endoplasmic reticulum (ER) calcium levels, which is significant for various cellular functions, including protein folding and cellular signaling. Recent studies have also linked VMP1 to the cellular response against viral infections and lipid droplet (LD). Dysregulation of VMP1 has been observed in several pathological conditions, including neurodegenerative diseases such as Parkinson's disease (PD), pancreatitis, hepatitis, and tumorogenesis, underscoring its potential as a therapeutic target. This review aims to provide an overview of VMP1's multifaceted roles and its implications in disease pathology.

Amino acid deprivation in cancer cells with compensatory autophagy induction increases sensitivity to autophagy inhibitors

Inhibition of autophagy is an important strategy in cancer therapy. However, prolonged inhibition of certain autophagies in established cancer cells may increase therapeutic resistance, though the underlying mechanisms of its induction and enhancement remain unclear. This study sought to elucidate the mechanisms of therapeutic resistance through repeated autophagy inhibition and amino acid deprivation (AD) in an in vitro model of in vivo chronic nutrient deprivation associated with cancer cell treatment. In the human cervical cancer cell line HeLa and human breast cancer cell line MCF-7, initial extracellular AD induced the immediate expression of endosomal microautophagy (eMI). However, repeated inhibition of eMI with U18666A and extracellular AD induced macroautophagy (MA) to compensate for reduced eMI, simultaneously decreasing cytotoxicity. Here, hyperphosphorylated JNK was transformed into a hypophosphorylated state, suggesting conversion of the cell death signal to a survival signal. In a nutrient medium, cell death could not be induced by MA inhibition. However, since LAT1 inhibitors induce intracellular AD, combining them with MA and eMI inhibitors successfully promoted cell death in resistant cells. Our study identified a novel therapeuic approach for promoting cell death and addressing therapeutic resistance in cancers under autophagy-inhibitor treatment.

Pharmacology Progresses and Applications of Chloroquine in Cancer Therapy

Chloroquine is a common antimalarial drug and is listed in the World Health Organization Standard List of Essential Medicines because of its safety, low cost and ease of use. Besides its antimalarial property, chloroquine also was used in anti-inflammatory and antivirus, especially in antitumor therapy. A mount of data showed that chloroquine mainly relied on autophagy inhibition to exert its antitumor effects. However, recently, more and more researches have revealed that chloroquine acts through other mechanisms that are autophagy-independent. Nevertheless, the current reviews lacked a comprehensive summary of the antitumor mechanism and combined pharmacotherapy of chloroquine. So here we focused on the antitumor properties of chloroquine, summarized the pharmacological mechanisms of antitumor progression of chloroquine dependent or independent of autophagy inhibition. Moreover, we also discussed the side effects and possible application developments of chloroquine. This review provided a more systematic and cutting-edge knowledge involved in the anti-tumor mechanisms and combined pharmacotherapy of chloroquine in hope of carrying out more in-depth exploration of chloroquine and obtaining more clinical applications.

Alpha-Hederin induces incomplete autophagic injury in non-small cell lung cancer by interfering with the lysosomal acidification

Lung cancer is the most common oncological disease worldwide, with non-small cell lung cancer accounting for approximately 85% of lung cancer cases. α-Hederin is a monodesmosidic triterpenoid saponin isolated from the leaves of Hedera helix L. or Nigella sativa and has been extensively studied for its antitumor activity against a variety of tumor cells. It has been suggested that α-Hederin is a potential regulator of autophagy and has high promise for application. However, the specific mechanism and characteristics of α-Hederin in regulating autophagy are not well understood. In this study, we confirmed the potential of α-Hederin application in lung cancer treatment and comprehensively explored the mechanism and characteristics of α-Hederin in regulating autophagy in lung cancer cells. Our results suggest that α-Hederin is an incomplete autophagy inducer that targets mTOR to activate the classical autophagic pathway, inhibits lysosomal acidification without significantly affecting the processes of autophagosome transport, lysosome biogenesis, autophagosome and lysosome fusion, and finally leads to impaired autophagic flux and triggers autophagic damage in NSCLC.

Toll-like receptor signaling in multiple myeloma cells promotes the expression of pro-survival genes B-cell lymphoma 2 and MYC and modulates the expression of B-cell maturation antigen

Infections are common in plasma cell cancer multiple myeloma (MM) due to disease-related immune deficiencies and cancer treatment. Myeloma cells express Toll-like receptors (TLRs), and TLR activation has been shown to induce proliferative and pro-survival signals in cancer cells. MM is a complex and heterogeneous disease, and expression levels of TLRs as well as downstream signaling components are likely to differ between patients. Here, we show that in a large cohort of patients, TLR1, TLR4, TLR6, TLR9, and TLR10 are the most highly expressed in primary CD138+ cells. Using an MM cell line expressing TLR4 and TLR9 as a model, we demonstrate that TLR4 and TLR9 activation promoted the expression of well-established pro-survival and oncogenes in MM such as MYC, IRF4, NFKB, and BCL2. TLR4 and TLR9 activation inhibited the efficacy of proteasome inhibitors bortezomib and carfilzomib, drugs used in the treatment of MM. Inhibiting the autophagosome-lysosome protein degradation pathway by hydroxychloroquine (HCQ) diminished the protective effect of TLR activation on proteasome inhibitor-induced cytotoxicity. We also found that TLR signaling downregulated the expression of TNFRSF17, the gene encoding for B-cell maturation antigen (BCMA). MYC, BCL2, and BCL2L1 were upregulated in approximately 50% of primary cells, while the response to TLR signaling in terms of TNFRSF17 expression was dichotomous, as an equal fraction of patients showed upregulation and downregulation of the gene. While proteasome inhibitors are part of first-line MM treatment, several of the new anti-MM immune therapeutic drugs target BCMA. Thus, TLR activation may render MM cells less responsive to commonly used anti-myeloma drugs.

Nanomaterials in crossroad of autophagy control in human cancers: Amplification of cell death mechanisms

Cancer is the result of genetic abnormalities that cause normal cells to grow into neoplastic cells. Cancer is characterized by several distinct features, such as uncontrolled cell growth, extensive spreading to other parts of the body, and the ability to resist treatment. The scientists have stressed the development of nanostructures as novel therapeutic options in suppressing cancer, in response to the emergence of resistance to standard medicines. One of the specific mechanisms with dysregulation during cancer is autophagy. Nanomaterials have the ability to specifically carry medications and genes, and they can also enhance the responsiveness of tumor cells to standard therapy while promoting drug sensitivity. The primary mechanism in this process relies on autophagosomes and their fusion with lysosomes to break down the components of the cytoplasm. While autophagy was initially described as a form of cellular demise, it has been demonstrated to play a crucial role in controlling metastasis, proliferation, and treatment resistance in human malignancies. The pharmacokinetic profile of autophagy modulators is poor, despite their development for use in cancer therapy. Consequently, nanoparticles have been developed for the purpose of delivering medications and autophagy modulators selectively and specifically to the cancer process. Furthermore, several categories of nanoparticles have demonstrated the ability to regulate autophagy, which plays a crucial role in defining the biological characteristics and response to therapy of tumor cells.

Guidelines for the role of autophagy in drug delivery vectors uptake pathways

The process of autophagy refers to the intracellular absorption of cytoplasm (such as proteins, nucleic acids, tiny molecules, complete organelles, and so on) into the lysosome, followed by the breakdown of that cytoplasm. The majority of cellular proteins are degraded by a process called autophagy, which is both a naturally occurring activity and one that may be induced by cellular stress. Autophagy is a system that can save cells' integrity in stressful situations by restoring metabolic basics and getting rid of subcellular junk. This happens as a component of an endurance response. This mechanism may have an effect on disease, in addition to its contribution to the homeostasis of individual cells and tissues as well as the control of development in higher species. The main aim of this study is to discuss the guidelines for the role of autophagy in drug delivery vector uptake pathways. In this paper, we discuss the meaning and concept of autophagy, the mechanism of autophagy, the role of autophagy in drug delivery vectors, autophagy-modulating drugs, nanostructures for delivery systems of autophagy modulators, etc. Later in this paper, we talk about how to deliver chemotherapeutics, siRNA, and autophagy inducers and inhibitors. We also talk about how hard it is to make a drug delivery system that takes nanocarriers' roles as autophagy modulators into account.

NCX1/Ca2+ promotes autophagy and decreases bortezomib activity in multiple myeloma through non-canonical NFκB signaling pathway

Although bortezomib (BTZ) is the cornerstone of anti-multiple myeloma (MM) therapy, the inevitable primary and secondary drug resistance still seriously affects the prognosis of patients. New treatment strategies are in need. Sodium-calcium exchanger 1 (NCX1) is a calcium-permeable ion transporter on the membrane, and our previous studies showed that low NCX1 confers inferior viability in MM cells and suppressed osteoclast differentiation. However, the effect of NCX1 on BTZ sensitivity of MM and its possible mechanism remain unclear. In this study, we investigated the effect of NCX1 on BTZ sensitivity in MM, focusing on cellular processes of autophagy and cell viability. Our results provide evidence that NCX1 expression correlates with MM disease progression and low NCX1 expression increases BTZ sensitivity. NCX1/Ca2+ triggered autophagic flux through non-canonical NFκB pathway in MM cells, leading to attenuated the sensitivity of BTZ. Knockdown or inhibition of NCX1 could potentiate the anti-MM activity of BTZ in vitro and vivo, and inhibition of autophagy sensitized NCX1-overexpressing MM cells to BTZ. In general, this work implicates NCX1 as a potential therapeutic target in MM with BTZ resistance and provides novel mechanistic insights into its vital role in combating BTZ resistance.

From Androgen Dependence to Independence in Prostate Cancer: Unraveling Therapeutic Potential and Proteomic Landscape of Hydroxychloroquine as an Autophagy Inhibitor

Prostate cancer is a major planetary health challenge wherein new ways of thinking drug discovery and therapeutics innovation are much needed. Numerous studies have shown that autophagy inhibition holds a significant role as an adjunctive intervention in prostate cancer. Hydroxychloroquine (HCQ) has gained considerable attention due to its established role as an autophagy inhibitor across diverse cancer types, but its proteomics landscape and systems biology in prostate cancer are currently lacking in the literature. This study reports the proteomic responses to HCQ in prostate cancer cells, namely, androgen-dependent LNCaP and androgen-independent PC3 cells. Differentially expressed proteins and proteome in HCQ-treated cells were determined by label-free quantification with nano-high-performance liquid chromatography and tandem mass spectrometry (nHPLC-MS/MS), and harnessing bioinformatics tools. In PC3 cells, there was a marked shift toward metabolic reprogramming, highlighted by an upregulation of mitochondrial proteins in oxidative phosphorylation and tricarboxylic acid cycle, suggesting an adaptive mechanism to maintain energy production under therapeutic stress. In contrast, LNCaP cells prioritized proteostasis and cell cycle regulation, indicating a more conservative adaptation strategy. To the best of our knowledge, this study is the first to demonstrate the differential responses of prostate cancer cells to autophagy inhibition by HCQ, suggesting that a combination therapy approach, targeting distinct pathways in androgen-independent and androgen-dependent cells, could represent a promising treatment strategy. Moreover, the varied proteomic responses observed between these cell lines underscore the importance of personalized medicine in cancer therapy. Future translational and clinical research on HCQ and prostate cancer are called for.

Oncolytic Myxoma virus Increases Autophagy in Multiple Myeloma

Objective

Multiple myeloma, which affects plasma cells, is the second most common hematological malignancy. Despite the development of new drugs and treatment protocols, patient survival has not reached the desired level. In this study, we investigated the effects of Myxoma virus (MYXV), an oncolytic virus, on autophagy in myeloma cells.

Materials and Methods

We analyzed protein expressions of ATG-5, p62, Beclin-1, LC3B, and the apoptosis marker Bcl-2 as autophagy markers in human U-266 and mouse MOPC-315 myeloma cell lines subjected to different doses of MYXV. In addition, autophagic images of myeloma cells were investigated using transmission electron microscopy (TEM).

Results

In the first 24 h, which is the early stage of autophagy, ATG-5 and Beclin-1 expression levels were increased in the U-266 and MOPC-315 cell lines in the groups that had received MYXV at a multiplicity of infection of 15. At 48 h, a significant increase was detected in the expression of LC3B, which is a late indicator. Autophagosomes were observed in myeloma cells by TEM.

Conclusion

MYXV shows an antimyeloma effect by increasing autophagy in myeloma cells.

Interplay between proteasome inhibitors and NF-κB pathway in leukemia and lymphoma: a comprehensive review on challenges ahead of proteasome inhibitors

The current scientific literature has extensively explored the potential role of proteasome inhibitors (PIs) in the NF-κB pathway of leukemia and lymphoma. The ubiquitin-proteasome system (UPS) is a critical component in regulating protein degradation in eukaryotic cells. PIs, such as BTZ, are used to target the 26S proteasome in hematologic malignancies, resulting in the prevention of the degradation of tumor suppressor proteins, the activation of intrinsic mitochondrial-dependent cell death, and the inhibition of the NF-κB signaling pathway. NF-κB is a transcription factor that plays a critical role in the regulation of apoptosis, cell proliferation, differentiation, inflammation, angiogenesis, and tumor migration. Despite the successful use of PIs in various hematologic malignancies, there are limitations such as resistant to these inhibitors. Some reports suggest that PIs can induce NF-κB activation, which increases the survival of malignant cells. This article discusses the various aspects of PIs' effects on the NF-κB pathway and their limitations. Video Abstract.

Autophagy indicators in oral squamous cell carcinoma

Autophagy plays an important role in maintaining cellular homeostasis. Dysregulation of autophagy has been linked to a number of diseases, including cancer. We retrospectively evaluated immunohistochemical expression of the autophagy markers LC3B and p62 and the autophagy regulator mTOR as an indicator of autophagy in 100 surgically resected primary oral squamous cell carcinoma (OSCC) samples and sought associations with various clinicopathological factors. The expression of all three proteins was significantly higher in malignant squamous cells than in benign squamous cells in the free mucosal margin adjacent to the OSCC. Male sex, higher tumour (T) stage, node (N) stage and tumour, node, metastasis (TNM) stage were significantly associated with high marker expression; age and histological grade showed no significant association. LC3B, p62 and mTOR expression were positively correlated with one another in OSCCs, and the correlation was significant for LC3B and mTOR as well as for LC3B and p62. Disease-free survival showed an inverse correlation with high mTOR expression. Our data suggest that autophagy inhibitors and mTOR inhibitors may have a therapeutic role in the treatment of OSCCs.

CRIP1 involves the pathogenesis of multiple myeloma via dual-regulation of proteasome and autophagy

BACKGROUND

Multiple myeloma (MM) is an incurable hematological malignancy of the plasma cells. The maintenance of protein homeostasis is critical for MM cell survival. Elevated levels of paraproteins in MM cells are cleared by proteasomes or lysosomes, which are independent but inter-connected with each other. Proteasome inhibitors (PIs) work as a backbone agent and successfully improved the outcome of patients; however, the increasing activity of autophagy suppresses the sensitivity to PIs treatment.

METHODS

The transcription levels of CRIP1 were explored in plasma cells obtained from healthy donors, patients with newly diagnosed multiple myeloma (NDMM), and relapsed/refractory multiple myeloma (RRMM) using Gene expression omnibus datasets. Doxycycline-inducible CRIP1-shRNA and CRIP1 overexpressed MM cell lines were constructed to explore the role of CRIP1 in MM pathogenesis. Proliferation, invasion, migration, proteasome activity and autophagy were examined in MM cells with different CRIP1 levels. Co-immunoprecipitation (Co-IP) with Tandem affinity purification/Mass spectrum (TAP/MS) was performed to identify the binding proteins of CRIP1. The mouse xenograft model was used to determine the role of CRIP1 in the proliferation and drug-resistance of MM cells.

FINDINGS

High CRIP1 expression was associated with unfavorable clinical outcomes in patients with MM and served as a biomarker for RRMM with shorter overall survival. In vitro and in vivo studies showed that CRIP1 plays a critical role in protein homeostasis via the dual regulation of the activities of proteasome and autophagy in MM cells. A combined analysis of RNA-seq, Co-IP and TAP/MS demonstrated that CRIP1 promotes proteasome inhibitors resistance in MM cells by simultaneously binding to de-ubiquitinase USP7 and proteasome coactivator PA200. CRIP1 promoted proteasome activity and autophagosome maturation by facilitating the dequbiquitination and stabilization of PA200.

INTERPRETATION

Our findings clarified the pivotal roles of the CRIP1/USP7/PA200 complex in ubiquitin-dependent proteasome degradation and autophagy maturation involved in the pathogenesis of MM.

FUNDING

A full list of funding sources can be found in the acknowledgements section.

Chloroquine and Chemotherapeutic Compounds in Experimental Cancer Treatment

Chloroquine (CQ) and its derivate hydroxychloroquine (HCQ), the compounds with recognized ability to suppress autophagy, have been tested in experimental works and in clinical trials as adjuvant therapy for the treatment of tumors of different origin to increase the efficacy of cytotoxic agents. Such a strategy can be effective in overcoming the resistance of cancer cells to standard chemotherapy or anti-angiogenic therapy. This review presents the results of the combined application of CQ/HCQ with conventional chemotherapy drugs (doxorubicin, paclitaxel, platinum-based compounds, gemcitabine, tyrosine kinases and PI3K/Akt/mTOR inhibitors, and other agents) for the treatment of different malignancies obtained in experiments on cultured cancer cells, animal xenografts models, and in a few clinical trials. The effects of such an approach on the viability of cancer cells or tumor growth, as well as autophagy-dependent and -independent molecular mechanisms underlying cellular responses of cancer cells to CQ/HCQ, are summarized. Although the majority of experimental in vitro and in vivo studies have shown that CQ/HCQ can effectively sensitize cancer cells to cytotoxic agents and increase the potential of chemotherapy, the results of clinical trials are often inconsistent. Nevertheless, the pharmacological suppression of autophagy remains a promising tool for increasing the efficacy of standard chemotherapy, and the development of more specific inhibitors is required.

Autophagy-related mechanisms for treatment of multiple myeloma

Multiple myeloma (MM) is a type of hematological cancer that occurs when B cells become malignant. Various drugs such as proteasome inhibitors, immunomodulators, and compounds that cause DNA damage can be used in the treatment of MM. Autophagy, a type 2 cell death mechanism, plays a crucial role in determining the fate of B cells, either promoting their survival or inducing cell death. Therefore, autophagy can either facilitate the progression or hinder the treatment of MM disease. In this review, autophagy mechanisms that may be effective in MM cells were covered and evaluated within the contexts of unfolded protein response (UPR), bone marrow microenvironment (BMME), drug resistance, hypoxia, DNA repair and transcriptional regulation, and apoptosis. The genes that are effective in each mechanism and research efforts on this subject were discussed in detail. Signaling pathways targeted by new drugs to benefit from autophagy in MM disease were covered. The efficacy of drugs that regulate autophagy in MM was examined, and clinical trials on this subject were included. Consequently, among the autophagy mechanisms that are effective in MM, the most suitable ones to be used in the treatment were expressed. The importance of 3D models and microfluidic systems for the discovery of new drugs for autophagy and personalized treatment was emphasized. Ultimately, this review aims to provide a comprehensive overview of MM disease, encompassing autophagy mechanisms, drugs, clinical studies, and further studies.

Hydroxychloroquine: Key therapeutic advances and emerging nanotechnological landscape for cancer mitigation

Hydroxychloroquine (HCQ) is a unique class of medications that has been widely utilized for the treatment of cancer. HCQ plays a dichotomous role by inhibiting autophagy induced by the tumor microenvironment (TME). Preclinical studies support the use of HCQ for anti-cancer therapy, especially in combination with conventional anti-cancer treatments since they sensitize tumor cells to drugs, potentiating the therapeutic activity. However, clinical evidence has suggested poor outcomes for HCQ due to various obstacles, including non-specific distribution, low aqueous solubility and low bioavailability at target sites, transport across tissue barriers, and retinal toxicity. These issues are addressable via the integration of HCQ with nanotechnology to produce HCQ-conjugated nanomedicines. This review aims to discuss the pharmacodynamic, pharmacokinetic and antitumor properties of HCQ. Furthermore, the antitumor performance of the nanoformulated HCQ is also reviewed thoroughly, aiming to serve as a guide for the HCQ-based enhanced treatment of cancers. The nanoencapsulation or nanoconjugation of HCQ with nanoassemblies appears to be a promising method for reducing the toxicity and improving the antitumor efficacy of HCQ.

Sensitivity of osteosarcoma cell lines to autophagy inhibition as determined by pharmacologic and genetic manipulation

Pharmacologic inhibition of autophagy can be achieved using lysosomotropic agents such as hydroxychloroquine (HCQ) that interfere with fusion of the autophagosome to the lysosome thus preventing completion of the recycling process. The goal of the present study is to determine the sensitivity of eight canine (cOSA) and four human (hOSA) osteosarcoma tumour cell lines to antiproliferative and cytotoxic effects of lysosomal autophagy inhibitors, and to compare these results to the autophagy-dependence measured using a CRISPR/Cas9 live-cell imaging assay in OSA and other tumour cell lines. Antiproliferative and cytotoxic response to HCQ and Lys05 was determined using live cell imaging and YOYO-1 staining. CRISPR/Cas9 live cell imaging screen was done using species specific guide RNA's and transfection of reagents into cells. Response to autophagy core genes was compared to response to an essential (PCNA) and non-essential (FOXO3A) gene. cOSA and hOSA cell lines showed similar antiproliferative and cytotoxic responses to HCQ and Lys05 with median lethal dose (Dm ) values ranging from 4.6-15.8 μM and 2.1-5.1 μM for measures of anti-proliferative response, respectively. A relationship was observed between antiproliferative responses to HCQ and Lys05 and VPS34 CRISPR score with Dm values correlating with VPS34 response (r = 0.968 and 0.887) in a species independent manner. The results show that a subset of cOSA and hOSA cell lines are autophagy-dependent and sensitive to HCQ at pharmacologically-relevant exposures.

MIOX inhibits autophagy to regulate the ROS -driven inhibition of STAT3/c-Myc-mediated epithelial-mesenchymal transition in clear cell renal cell carcinoma

The specific mechanism of clear cell renal cell carcinoma (ccRCC) progression, a pathological type that accounts for the highest proportion of RCC, remains unclear. In this study, bioinformatics analysis of scRNA-seq dataset in ccRCC revealed that MIOX was a gene specifically down-regulated in tumor epithelial cells of ccRCC. Analysis of the TCGA database further validated the association between decreased MIOX mRNA levels and ccRCC malignant phenotype and poor prognosis. Immunohistochemistry indicated the down-regulation of MIOX in ccRCC tissues compared to paired adjacent renal tissues, with further down-regulation of MIOX in the primary tumors of patients with primary metastasis compared to those without metastasis. Also, patients with low expression of MIOX showed shorter metastasis-free survival (MFS) compared to those with high MIOX expression. In vitro results showed that overexpression of MIOX in ccRCC cells inhibited the proliferation, migration and invasion and promoted apoptosis. Mechanistically, up-regulation of MIOX inhibited autophagy to elevate the levels of ROS, and thus suppressed STAT3/c-Myc-mediated epithelial-mesenchymal transition in ccRCC cells. In vivo data further confirmed that increased MIOX expression suppressed the growth and proliferation of RCC cells and reduced the ability of RCC cells to form metastases in the lung. This study demonstrates that MIOX is an important regulatory molecule of ccRCC, which is conducive to understanding the potential molecular mechanism of ccRCC progression.

Identification of Fangchinoline as a novel autophagy inhibitor with an adjuvant of chemotherapy against lung cancer

Autophagy is a fundamental recycling pathway that enhances cellular resilience, promoting survival. However, this survival mechanism can impede anti-cancer treatment strategies designed to induce cell death. In this study, we identified a novel autophagy inhibitor, Fangchinoline (Fan) isolated from the traditional Chinese medicine Stephania tetrandra. We speculated that when Fan blocks autophagy, cancer cells lose substantial self-preservation abilities during treatment. Firstly, we examined in detail the mechanism through which Fan inhibits autophagy. Specifically, Fan induced a significant increase in autophagosomes, as indicated by GFP-LC3 labeling, confirmed by the up-regulation of LC3-II. The autophagy receptor protein p62 was also up-regulated, suggesting a potential inhibition of autophagy flux. We further ruled out the possibility of fusion barriers between lysosomes and autophagosomes, as confirmed by their co-localization in double fluorescence staining. However, the lysosomal acid environment might be compromised, as suggested by the diminished fluorescence of acidity-sensitive dyes in the lysosomes and the corresponding decrease in mature forms of lysosomal cathepsin. To test the anti-cancer potential of Fan, we combined it with Cisplatin (Cis) or Paclitaxel (PTX) for lung cancer cell treatment. This combined treatment demonstrated a synergistically enhanced killing effect. These promising anti-tumor results were also replicated in a xenografted tumor model. The significance of this research lies in the identification of Fan as a potent autophagy inhibitor and its potential to enhance the efficacy of existing anti-cancer drugs. By unraveling the mechanisms of Fan's action on autophagy and demonstrating its synergistic effect in combination therapies, our study provides valuable insights for developing novel strategies to overcome autophagy-mediated resistance in cancer treatment.

TRIM21 enhances bortezomib sensitivity in multiple myeloma by halting prosurvival autophagy

Bortezomib (bort) is an effective therapeutic agent for patients with multiple myeloma (MM); however, most patients develop drug resistance. Autophagy, a highly conserved process that recycles cytosol or entire organelles via lysosomal activity, is essential for the survival, homeostasis, and drug resistance in MM. Growing evidence has highlighted that E3 ligase tripartite motif-containing protein 21 (TRIM21) not only interacts with multiple autophagy regulators but also participates in drug resistance in various cancers. However, to date, the direct substrates and additional roles of TRIM21 in MM remain unexplored. In this study, we demonstrated that low TRIM21 expression is a factor for relapse in MM. TRIM21 knockdown (KD) made MM cells more resistant to bort, whereas TRIM21 overexpression (OE) resulted in increased MM sensitivity to bort. Proteomic and phosphoproteomic studies of TRIM21 KD MM cells showed that bort resistance was associated with increased oxidative stress and elevated prosurvival autophagy. Our results showed that TRIM21 KD MM cell lines induced prosurvival autophagy after bort treatment, suppressing autophagy by 3-methyladenine treatment or by the short hairpin RNA of autophagy-related gene 5 (ATG5)-restored-bort sensitivity. Indeed, ATG5 expression was increased and decreased by TRIM21 KD and OE, respectively. TRIM21 affected autophagy by ubiquitinating ATG5 through K48 for proteasomal degradation. Importantly, we confirmed that TRIM21 could potentiate the antimyeloma effect of bort through in vitro and in vivo experiments. Overall, our findings define the key role of TRIM21 in MM bort resistance and provide a foundation for a novel targeted therapeutic approach.

Hydroxychloroquine-Loaded Chitosan Nanoparticles Induce Anticancer Activity in A549 Lung Cancer Cells: Design, BSA Binding, Molecular Docking, Mechanistic, and Biological Evaluation

The current study describes the encapsulation of hydroxychloroquine, widely used in traditional medicine due to its diverse pharmacological and medicinal uses, in chitosan nanoparticles (CNPs). This work aims to combine the HCQ drug with CS NPs to generate a novel nanocomposite with improved characteristics and bioavailability. HCQ@CS NPs are roughly shaped like roadways and have a smooth surface with an average size of 159.3 ± 7.1 nm, a PDI of 0.224 ± 0.101, and a zeta potential of +46.6 ± 0.8 mV. To aid in the development of pharmaceutical systems for use in cancer therapy, the binding mechanism and affinity of the interaction between HCQ and HCQ@CS NPs and BSA were examined using stopped-flow and other spectroscopic approaches, supplemented by molecular docking analysis. HCQ and HCQ@CS NPs binding with BSA is driven by a ground-state complex formation that may be accompanied by a non-radiative energy transfer process, and binding constants indicate that HCQ@CS NPs-BSA was more stable than HCQ-BSA. The stopped-flow analysis demonstrated that, in addition to increasing BSA affinity, the nanoformulation HCQ@CS NPS changes the binding process and may open new routes for interaction. Docking experiments verified the development of the HCQ-BSA complex, with HCQ binding to site I on the BSA structure, primarily with the amino acids, Thr 578, Gln 579, Gln 525, Tyr 400, and Asn 404. Furthermore, the nanoformulation HCQ@CS NPS not only increased cytotoxicity against the A549 lung cancer cell line (IC50 = 28.57 ± 1.72 μg/mL) compared to HCQ (102.21 ± 0.67 μg/mL), but also exhibited higher antibacterial activity against both Gram-positive and Gram-negative bacteria when compared to HCQ and chloramphenicol, which is in agreement with the binding constants. The nanoformulation developed in this study may offer a viable therapy option for A549 lung cancer.

Overcoming proteasome inhibitor resistance in the immunotherapy era

Proteasome inhibitors (PIs) are a fascinating class of small molecules that disrupt protein homeostasis and are highly efficacious in the blood cancer multiple myeloma. However, PIs are not curative, and overcoming PI resistance to extend patient survival remains a major unmet need. Recent strategies to overcome PI resistance, including inhibiting alternative protein homeostasis pathways and targeting the mitochondrion as a nexus of metabolic adaptation to PIs, are gaining momentum. However, these focused approaches may be surpassed or even obviated by quickly emerging immunotherapy strategies that do not selectively target PI resistance mechanisms but are highly efficacious in PI-resistant disease, nonetheless. Informed by insights from these promising areas of research moving in parallel, we propose that pharmacological strategies to enforce immunotherapeutic vulnerabilities in resistant disease may provide a unified outlook to overcome PI resistance in a 'new era' of myeloma treatment.

Update on Autophagy Inhibitors in Cancer: Opening up to a Therapeutic Combination with Immune Checkpoint Inhibitors

Autophagy is a highly conserved and natural degradation process that helps maintain cell homeostasis through the elimination of old, worn, and defective cellular components, ensuring proper cell energy intake. The degradative pathway constitutes a protective barrier against diverse human diseases including cancer. Autophagy basal level has been reported to be completely dysregulated during the entire oncogenic process. Autophagy influences not only cancer initiation, development, and maintenance but also regulates cancer response to therapy. Currently, autophagy inhibitor candidates mainly target the early autophagy process without any successful preclinical/clinical development. Lessons learned from autophagy pharmaceutical manipulation as a curative option progressively help to improve drug design and to encounter new targets of interest. Combinatorial strategies with autophagy modulators are supported by abundant evidence, especially dealing with immune checkpoint inhibitors, for which encouraging preclinical results have been recently published. GNS561, a PPT1 inhibitor, is a promising autophagy modulator as it has started a phase 2 clinical trial in liver cancer indication, combined with atezolizumab and bevacizumab, an assessment without precedent in the field. This approach paves a new road, leading to the resurgence of anticancer autophagy inhibitors as an attractive therapeutic target in cancer.

Unmet needs and future perspectives in hydroxychloroquine retinopathy

Retinopathy is a well-recognized toxic effect of hydroxychloroquine treatment. As hydroxychloroquine retinopathy is potentially a vision-threatening condition, early detection is imperative to minimize vision loss due to drug toxicity. However, early detection of hydroxychloroquine retinopathy is still challenging even with modern retinal imaging techniques. No treatment has been established for this condition, except for drug cessation to minimize further damage. In this perspective article, we aimed to summarize the knowledge gaps and unmet needs in current clinical practice and research in hydroxychloroquine retinopathy. The information presented in this article may help guide the future directions of screening practices and research in hydroxychloroquine retinopathy.

Polymorphisms within Autophagy-Related Genes as Susceptibility Biomarkers for Multiple Myeloma: A Meta-Analysis of Three Large Cohorts and Functional Characterization

Multiple myeloma (MM) arises following malignant proliferation of plasma cells in the bone marrow, that secrete high amounts of specific monoclonal immunoglobulins or light chains, resulting in the massive production of unfolded or misfolded proteins. Autophagy can have a dual role in tumorigenesis, by eliminating these abnormal proteins to avoid cancer development, but also ensuring MM cell survival and promoting resistance to treatments. To date no studies have determined the impact of genetic variation in autophagy-related genes on MM risk. We performed meta-analysis of germline genetic data on 234 autophagy-related genes from three independent study populations including 13,387 subjects of European ancestry (6863 MM patients and 6524 controls) and examined correlations of statistically significant single nucleotide polymorphisms (SNPs; p < 1 × 10-9) with immune responses in whole blood, peripheral blood mononuclear cells (PBMCs), and monocyte-derived macrophages (MDM) from a large population of healthy donors from the Human Functional Genomic Project (HFGP). We identified SNPs in six loci, CD46, IKBKE, PARK2, ULK4, ATG5, and CDKN2A associated with MM risk (p = 4.47 × 10-4-5.79 × 10-14). Mechanistically, we found that the ULK4rs6599175 SNP correlated with circulating concentrations of vitamin D3 (p = 4.0 × 10-4), whereas the IKBKErs17433804 SNP correlated with the number of transitional CD24+CD38+ B cells (p = 4.8 × 10-4) and circulating serum concentrations of Monocyte Chemoattractant Protein (MCP)-2 (p = 3.6 × 10-4). We also found that the CD46rs1142469 SNP correlated with numbers of CD19+ B cells, CD19+CD3- B cells, CD5+IgD- cells, IgM- cells, IgD-IgM- cells, and CD4-CD8- PBMCs (p = 4.9 × 10-4-8.6 × 10-4) and circulating concentrations of interleukin (IL)-20 (p = 0.00082). Finally, we observed that the CDKN2Ars2811710 SNP correlated with levels of CD4+EMCD45RO+CD27- cells (p = 9.3 × 10-4). These results suggest that genetic variants within these six loci influence MM risk through the modulation of specific subsets of immune cells, as well as vitamin D3-, MCP-2-, and IL20-dependent pathways.

Recent advances in targeting autophagy in cancer

Autophagy is a cellular homeostasis mechanism that fuels the proliferation and survival of advanced cancers by degrading and recycling organelles and proteins. Preclinical studies have identified that within an established tumor, tumor cell autophagy and host cell autophagy conspire to support tumor growth. A growing body of evidence suggests that autophagy inhibition can augment the efficacy of chemotherapy, targeted therapy, or immunotherapy to enhance tumor shrinkage. First-generation autophagy inhibition trials in cancer using the lysosomal inhibitor hydroxychloroquine (HCQ) have produced mixed results but have guided the way for the development of more potent and specific autophagy inhibitors in clinical trials. In this review, we will discuss the role of autophagy in cancer, newly discovered molecular mechanisms of the autophagy pathway, the effects of autophagy modulation in cancer and host cells, and novel autophagy inhibitors that are entering clinical trials.

Autophagy: A Potential Therapeutic Target to Tackle Drug Resistance in Multiple Myeloma

Multiple myeloma (MM) is the second most prevalent hematologic malignancy. In the past few years, the survival of MM patients has increased due to the emergence of novel drugs and combination therapies. Nevertheless, one of the significant obstacles in treating most MM patients is drug resistance, especially for individuals who have experienced relapses or developed resistance to such cutting-edge treatments. One of the critical processes in developing drug resistance in MM is autophagic activity, an intracellular self-digestive process. Several possible strategies of autophagy involvement in the induction of MM-drug resistance have been demonstrated thus far. In multiple myeloma, it has been shown that High mobility group box protein 1 (HMGB1)-dependent autophagy can contribute to drug resistance. Moreover, activation of autophagy via proteasome suppression induces drug resistance. Additionally, the effectiveness of clarithromycin as a supplemental drug in treating MM has been reported recently, in which autophagy blockage is proposed as one of the potential action mechanisms of CAM. Thus, a promising therapeutic approach that targets autophagy to trigger the death of MM cells and improve drug susceptibility could be considered. In this review, autophagy has been addressed as a survival strategy crucial for drug resistance in MM.

Nanomedicine for autophagy modulation in cancer therapy: a clinical perspective

In recent years, progress in nanotechnology provided new tools to treat cancer more effectively. Advances in biomaterials tailored for drug delivery have the potential to overcome the limited selectivity and side effects frequently associated with traditional therapeutic agents. While autophagy is pivotal in determining cell fate and adaptation to different challenges, and despite the fact that it is frequently dysregulated in cancer, antitumor therapeutic strategies leveraging on or targeting this process are scarce. This is due to many reasons, including the very contextual effects of autophagy in cancer, low bioavailability and non-targeted delivery of existing autophagy modulatory compounds. Conjugating the versatile characteristics of nanoparticles with autophagy modulators may render these drugs safer and more effective for cancer treatment. Here, we review current standing questions on the biology of autophagy in tumor progression, and precursory studies and the state-of-the-art in harnessing nanomaterials science to enhance the specificity and therapeutic potential of autophagy modulators.

Effects of invivo CXCR4 Blockade and Proteasome Inhibition on Bone Marrow Plasma Cells in HLA-Sensitized Kidney Transplant Candidates

To date, plasma cell (PC)-targeted therapies have been limited by suboptimal PC depletion and antibody rebound. We hypothesized this is partly because of PC residence in protective bone marrow (BM) microenvironments. The purpose of this proof-of-concept study was to examine the effects of the CXCR4 antagonist, plerixafor, on PC BM residence; its safety profile (alone and in combination with a proteasome inhibitor, bortezomib); and the transcriptional effect on BMPCs in HLA-sensitized kidney transplant candidates. Participants were enrolled into 3 groups: group A (n = 4), plerixafor monotherapy; and groups B (n = 4) and C (n = 4), plerixafor and bortezomib combinations. CD34⁺ stem cell and PC levels increased in the blood after plerixafor treatment. PC recovery from BM aspirates varied depending on the dose of plerixafor and bortezomib. Single-cell RNA sequencing on BMPCs from 3 group C participants pretreatment and posttreatment revealed multiple populations of PCs, with a posttreatment enrichment of oxidative phosphorylation, proteasome assembly, cytoplasmic translation, and autophagy-related genes. Murine studies demonstrated dually inhibiting the proteasome and autophagy resulted in greater BMPC death than did monotherapies. In conclusion, this pilot study revealed anticipated effects of combined plerixafor and bortezomib on BMPCs, an acceptable safety profile, and suggests the potential for autophagy inhibitors in desensitization regimens.

Crosstalk between autophagy and immune cell infiltration in the tumor microenvironment

Autophagy is a conserved process for self-degradation and provides cells with a rescue mechanism to respond to circumstances such as stress and starvation. The role of autophagy in cancer is extremely complex and often paradoxical. Most of the related published studies on tumors are always focused on cancer cells. However, present studies gradually noticed the significance of autophagy in the tumor microenvironment. These studies demonstrate that autophagy and immunity work synergistically to affect tumor progression, indicating that autophagy could become a potential target for cancer immunotherapy. Therefore, it is crucial to clarify the correlation between autophagy and various tumor-infiltrating immune cells in the tumor microenvironment. The context-dependent role of autophagy is critical in the design of therapeutic strategies for cancer.