Higher proteotoxic stress rather than mitochondrial damage is involved in higher neurotoxicity of bortezomib compared to carfilzomib

PSME2 promotes malignant progression through autophagy modulation via IL-6/STAT3 signaling pathway in esophageal squamous cell carcinoma

AIMS

This study aims to investigate the expression, clinical relevance, and functional roles of PSME2 in esophageal squamous cell carcinoma (ESCC).

MATERIALS AND METHODS

The biomarkers for ESCC were identified through comprehensive analysis of publicly available mRNA transcriptome data obtained from TCGA and GEO databases. The mRNA and protein expression levels of PSME2 in ESCC were validated using two independent cohorts of ESCC samples. The proliferation, migration, invasion, and autophagy activity of ESCC cells were evaluated in vitro through the knockdown of PSME2 or PR171. The effects of the knockdown of PSME2, STAT3 inhibitor WP1066, and autophagy inhibitor chloroquine on the tumorigenic potential of ESCC cells were also assessed through an in vivo subcutaneous tumor model established in nude mice.

KEY FINDINGS

The result obtained indicates the upregulation of PSME2 in ESCC, suggesting poor prognosis. The result also shows that the knockdown of PSME2 and PR171 triggers the reduction in ESCC cell proliferation, migration, and invasion. Thus, it buttresses the fact that PSME2 knockdown induced autophagy through the IL6/STAT3 pathway, leading to cell death resistance. The result also linked the suppression of tumor growth to the knockdown of PSME2 and WP1066 or chloroquine, suggesting that targeting these proteins may be a potential therapeutic strategy for inhibiting tumor progression.

SIGNIFICANCE

The study shows the promising role of PSME2 as a therapeutic target in ESCC management. The combined inhibition of PSME2 and activated pathways ensures effective suppression of tumor growth and proliferation, thus offering a novel strategy for better treatment outcomes in ESCC patients.

Post-Translational Modifications in Multiple Myeloma: Mechanisms of Drug Resistance and Therapeutic Opportunities

Multiple myeloma (MM) remains an incurable hematologic malignancy due to the inevitable development of drug resistance, particularly in relapsed or refractory cases. Post-translational modifications (PTMs), including phosphorylation, ubiquitination, acetylation, and glycosylation, play pivotal roles in regulating protein function, stability, and interactions, thereby influencing MM pathogenesis and therapeutic resistance. This review comprehensively explores the mechanisms by which dysregulated PTMs contribute to drug resistance in MM, focusing on their impact on key signaling pathways, metabolic reprogramming, and the tumor microenvironment. We highlight how PTMs modulate drug uptake, alter drug targets, and regulate cell survival signals, ultimately promoting resistance to PIs, IMiDs, and other therapeutic agents. Furthermore, we discuss emerging therapeutic strategies targeting PTM-related pathways, which offer promising avenues for overcoming resistance to treatment. By integrating preclinical and clinical insights, this review underscores the potential of PTM-targeted therapies to enhance treatment efficacy and improve patient outcomes in MM.

Cancer Drug Bortezomib, a Proteasomal Inhibitor, Triggers Cytotoxicity in Microvascular Endothelial Cells via Multi-Organelle Stress

Proteasomes maintain cellular homeostasis by degrading abnormal proteins, while cancer cells exploit them for survival, becoming a key chemotherapeutic target. Bortezomib (BTZ), a reversible proteasomal inhibitor, is a front-line treatment for multiple myeloma, mantle cell lymphoma, and non-small cell lung cancer. However, its efficacy is limited by severe side effects, including neurotoxicity and cardiovascular distress, with its toxicity mechanisms largely unexplored. Here, we discover that Bortezomib (BTZ), is cytotoxic to non-cancerous cells distinctly from Carfilzomib (CFZ), the second-line irreversible PI. BTZ or CFZ is administered intravenously, impacting blood vessel (vascular) endothelial cells. We used human pulmonary microvascular endothelial cells (HPMECs) to demonstrate that BTZ but not CFZ elicits endoplasmic reticulum (ER) stress, mitochondrial membrane compromise, mitochondrial reactive oxygen species (ROS) accumulation, and Caspase (CASP)9 activation (mediator of Intrinsic apoptosis) within fifteen hours of treatment. By twenty-four hours, BTZ-treated cells display cleavage of CASP8 (mediator of extrinsic apoptosis), activation of CASP3 (terminal executioner of apoptosis), cell-death and vascular barrier loss. Pan-caspase inhibitor zVAD significantly rescues BTZ-treated cells from cytotoxicity. Both BTZ and CFZ effectively kill MM cells. These findings reveal novel insights into fundamental signaling of regular cells where reversible inhibition of the proteasome dictates a unique cascade of stress distinct from irreversible inhibition. These harmful effects of BTZ emphasize the need to re- evaluate its use as a frontline chemotherapy for MM.

Highlights

Reversible proteasomal inhibitor Bortezomib is cytotoxic to non-cancerous, microvascular endothelial cellsIn endothelial cells, Bortezomib, but not irreversible inhibitor Carfilzomib, activates temporal cascade of caspases (Caspase-9, Caspase-8, Caspase-3) triggering apoptosisCaspase activation results from ER stress (via the IRE1α-CHOP) pathway and mitochondrial stress (ROS accumulation) independently from contribution from extrinsic signal via TNFBortezomib-dependent cytotoxicity compromises endothelial barrier potential.

The ameliorative effects of chrysin on bortezomib-induced nephrotoxicity in rats: Reduces oxidative stress, endoplasmic reticulum stress, inflammation damage, apoptotic and autophagic death

AIM

Bortezomib is a proteasome inhibitor antineoplastic agent that was the first to be approved for cancer treatment. One of bortezomib's most prominent dose-limiting effects is nephrotoxicity; the underlying mechanism is believed to be oxidative stress. Chrysin is a compound found actively in honey and many plant species and stands out with its antioxidant properties. The present study aimed to determine the ameliorative effects of chrysin in bortezomib-induced nephrotoxicity.

MATERIAL-METHOD

Thirty-five male Wistar rats were divided into control, BTZ, CHR, BTZ + CHR25, and BTZ + CHR50. Biochemical, molecular, Western blot, and histological methods analyzed renal function indicators, oxidative stress, endoplasmic reticulum stress, inflammation, apoptosis, and damage pathways.

RESULTS

Chrysin decreased oxidative stress by reducing oxidants (MDA) and increasing antioxidants (SOD, CAT, Gpx, GSH, Nrf-2, HO-1, NQO1). Chrysin reduced endoplasmic reticulum stress by decreasing ATF-6, PERK, IRE1, and GRP-78 levels. Chrysin reduced inflammation damage by inhibiting the NF-κB pathway. Chrysin exhibited protective properties against apoptotic damage by decreasing Bax and Caspase-3 levels and increasing Bcl-2 levels. In addition, chrysin improved renal function and structural integrity and exhibited healing properties against toxic damage in tissue structure.

CONCLUSION

Overall, chrysin exhibited an ameliorative effect against bortezomib-induced nephrotoxicity.

Bortezomib-induced peripheral neuropathy: Clinical features, molecular basis, and therapeutic approach

Bortezomib is the first-line standard and most effective chemotherapeutic for multiple myeloma; however, bortezomib-induced peripheral neuropathy (BIPN) severely affects the chemotherapy regimen and has long-term impact on patients under maintenance therapy. The pathogenesis of BIPN is poorly understood, and basic research and development of BIPN management drugs are in early stages. Besides chemotherapy dose reduction and regimen modification, no recommended prevention and treatment approaches are available for BIPN apart from the International Myeloma Working Group guidelines for peripheral neuropathy in myeloma. An in-depth exploration of the pathogenesis of BIPN, development of additional therapeutic approaches, and identification of risk factors are needed. Optimizing effective and standardized BIPN treatment plans and providing more decision-making evidence for clinical diagnosis and treatment of BIPN are necessary. This article reviews the recent advances in BIPN research; provides an overview of clinical features, underlying molecular mechanisms, and therapeutic approaches; and highlights areas for future studies.

Resolving therapy resistance mechanisms in multiple myeloma by multiomics subclone analysis

Intratumor heterogeneity as a clinical challenge becomes most evident after several treatment lines, when multidrug-resistant subclones accumulate. To address this challenge, the characterization of resistance mechanisms at the subclonal level is key to identify common vulnerabilities. In this study, we integrate whole-genome sequencing, single-cell (sc) transcriptomics (scRNA sequencing), and chromatin accessibility (scATAC sequencing) together with mitochondrial DNA mutations to define subclonal architecture and evolution for longitudinal samples from 15 patients with relapsed or refractory multiple myeloma. We assess transcriptomic and epigenomic changes to resolve the multifactorial nature of therapy resistance and relate it to the parallel occurrence of different mechanisms: (1) preexisting epigenetic profiles of subclones associated with survival advantages, (2) converging phenotypic adaptation of genetically distinct subclones, and (3) subclone-specific interactions of myeloma and bone marrow microenvironment cells. Our study showcases how an integrative multiomics analysis can be applied to track and characterize distinct multidrug-resistant subclones over time for the identification of molecular targets against them.

Molecular Cardiotoxic Effects of Proteasome Inhibitors Carfilzomib and Ixazomib and Their Combination with Dexamethasone Involve Mitochondrial Dysregulation

With the development and approval of new proteasome inhibitors, proteasome inhibition is increasingly recognized in cancer therapy. Besides successful anti-cancer effects in hematological cancers, side effects such as cardiotoxicity are limiting effective treatment. In this study, we used a cardiomyocyte model to investigate the molecular cardiotoxic mechanisms of carfilzomib (CFZ) and ixazomib (IXZ) alone or in combination with the immunomodulatory drug dexamethasone (DEX) which is frequently used in combination therapies in the clinic. According to our findings, CFZ showed a higher cytotoxic effect at lower concentrations than IXZ. DEX combination attenuated the cytotoxicity for both proteasome inhibitors. All drug treatments caused a marked increase in K48 ubiquitination. Both CFZ and IXZ caused an upregulation in cellular and endoplasmic reticulum stress protein (HSP90, HSP70, GRP94, and GRP78) levels and DEX combination attenuated the increased stress protein levels. Importantly, IXZ and IXZ-DEX treatments caused upregulation of mitochondria fission and fusion gene expression levels higher than caused by CFZ and CFZ-DEX combination. The IXZ-DEX combination reduced the levels of OXPHOS proteins (Complex II-V) more than the CFZ-DEX combination. Reduced mitochondrial membrane potential and ATP production were detected with all drug treatments in cardiomyocytes. Our findings suggest that the cardiotoxic effect of proteasome inhibitors may be due to their class effect and stress response and mitochondrial dysfunction may be involved in the cardiotoxicity process.

Animal models of chemotherapy-induced peripheral neuropathy for hematological malignancies: A review

Chemotherapy is one of the main treatments for hematologic malignancies. However, chemotherapy-induced peripheral neuropathy (CIPN) is one of the most common long-term toxic reactions in chemotherapy, and the occurrence of CIPN affects patients' quality of life and can cause interruption of chemotherapy in severe cases, thus reducing the efficacy of chemotherapy. We currently summarize the existing CIPN animal models, including the characteristics of several common animal models such as bortezomib-induced peripheral neuropathy, vincristine-induced peripheral neuropathy, and oxaliplatin-induced peripheral neuropathy. It was found that CIPN may lead to behavioral, histopathological, and neurophysiological changes inducing peripheral neuropathy. However, the mechanism of CIPN has not been fully elucidated, especially the prevention and treatment protocols need to be improved. Therefore, this review article summarizes the progress of research on CIPN animal models and the possible mechanisms and treatment of CIPN.

The Effect of Ex-Vivo Hyaluronic Acid on Myofibroblast and Collagen in Dupuytren Disease

Background: Dupuytren disease (DD) is characterised by increased myofibroblast/fibroblast activity and type3/type1 collagen ratios. Hyaluronic acid (HA) is major component of the extracellular matrix and some studies have showed that HA limits myofibroblast activity and decreases type3/type1 collagen ratio. The aim of this study is to determine the effect of the ex-vivo application of HA on cultured fibroblasts obtained from normal and diseased tissue from patients with DD. This is the initial step towards defining the use of HA as a new approach for medical treatment of DD. Methods: Tissue samples were obtained from both healthy forearm (C) and unhealthy palmar (D) fascia of patients undergoing surgery for DD. Tissue samples were cultured and divided into four groups depending on the addition of HA [C(HA-), C(HA+), D(HA-) and D(HA+)]. The tissues were evaluated using Western blot to detect effect of HA on myofibroblast (by measuring alpha smooth muscle actin [α-SMA) and on the ratio of type3/type1 collagen by measuring collagen type1 alpha 1 Chain (COL1A1) and collagen type3 alpha 1 Chain (COL3A1). Results: The rate of the average α-SMA value in the D(HA+) group was significantly lower compared to that of the D(HA-) group. The average ratio of type3/type1 collagen in the D(HA+) group was significantly lower compared to the D(HA-) group. Conclusions: The ex-vivo application of HA on cultured fibroblasts obtained from patients with DD resulted in a decrease in myofibroblast/fibroblast activity and type3/type1 collagen ratios. This may pave the way for clinical application of HA in the treatment of DD.

Current and Emerging Pharmacotherapeutic Interventions for the Treatment of Peripheral Nerve Disorders

Peripheral nerve disorders are caused by a range of different aetiologies. The range of causes include metabolic conditions such as diabetes, obesity and chronic kidney disease. Diabetic neuropathy may be associated with severe weakness and the loss of sensation, leading to gangrene and amputation in advanced cases. Recent studies have indicated a high prevalence of neuropathy in patients with chronic kidney disease, also known as uraemic neuropathy. Immune-mediated neuropathies including Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy may cause significant physical disability. As survival rates continue to improve in cancer, the prevalence of treatment complications, such as chemotherapy-induced peripheral neuropathy, has also increased in treated patients and survivors. Notably, peripheral neuropathy associated with these conditions may be chronic and long-lasting, drastically affecting the quality of life of affected individuals, and leading to a large socioeconomic burden. This review article explores some of the major emerging clinical and experimental therapeutic agents that have been investigated for the treatment of peripheral neuropathy due to metabolic, toxic and immune aetiologies.

Ubiquitin Proteasome System and Microtubules Are Master Regulators of Central and Peripheral Nervous System Axon Degeneration

Axonal degeneration is an active process that differs from neuronal death, and it is the hallmark of many disorders affecting the central and peripheral nervous system. Starting from the analyses of Wallerian degeneration, the simplest experimental model, here we describe how the long projecting neuronal populations affected in Parkinson’s disease and chemotherapy-induced peripheral neuropathies share commonalities in the mechanisms and molecular players driving the earliest phase of axon degeneration. Indeed, both dopaminergic and sensory neurons are particularly susceptible to alterations of microtubules and axonal transport as well as to dysfunctions of the ubiquitin proteasome system and protein quality control. Finally, we report an updated review on current knowledge of key molecules able to modulate these targets, blocking the on-going axonal degeneration and inducing neuronal regeneration. These molecules might represent good candidates for disease-modifying treatment, which might expand the window of intervention improving patients’ quality of life.

Chirality and asymmetry increase the potency of candidate ADRM1/RPN13 inhibitors

Bortezomib and the other licensed 20S proteasome inhibitors show robust activity against liquid tumors like multiple myeloma, but have disappointed against solid tumors including ovarian cancer. Consequently, interest is mounting in alternative non-peptide based drugs targeting the proteasome’s 19S regulatory particle subunit, including its ubiquitin receptor RPN13. RA183 and RA375 are more potent analogs of the prototypic inhibitor of RPN13 (iRPN13) called RA190, and they show promise for the treatment of ovarian cancer. Here we demonstrate that rendering these candidate RPN13 inhibitors chiral and asymmetric through the addition of a single methyl to the core piperidone moiety increases their potency against cancer cell lines, with the S-isomer being more active than the R-isomer. The enhanced cancer cell cytotoxicities of these compounds are associated with improved binding to RPN13 in cell lysates, ATP depletion by inhibition of glycolysis and mitochondrial electron chain transport, mitochondrial depolarization and perinuclear clustering, oxidative stress and glutathione depletion, and rapid accumulation of high molecular weight polyubiquitinated proteins with a consequent unresolved ubiquitin proteasome system (UPS) stress response. Cytotoxicity was associated with an early biomarker of apoptosis, increased surface annexin V binding. As for cisplatin, BRCA2 and ATM deficiency conferred increased sensitivity to these iRPN13s. Ubiquitination plays an important role in coordinating DNA damage repair and the iRPN13s may compromise this process by depletion of monomeric ubiquitin following its sequestration in high molecular weight polyubiquitinated protein aggregates. Indeed, a synergistic cytotoxic response was evident upon treatment of several ovarian cancer cell lines with either cisplatin or doxorubicin and our new candidate iRPN13s, suggesting that such a combination approach warrants further exploration for the treatment of ovarian cancer.

Abnormal Mitochondria-Endoplasmic Reticulum Communication Promotes Myocardial Infarction

Myocardial infarction is characterized by cardiomyocyte death, and can be exacerbated by mitochondrial damage and endoplasmic reticulum injury. In the present study, we investigated whether communication between mitochondria and the endoplasmic reticulum contributes to cardiomyocyte death after myocardial infarction. Our data demonstrated that hypoxia treatment (mimicking myocardial infarction) promoted cardiomyocyte death by inducing the c-Jun N-terminal kinase (JNK) pathway. The activation of JNK under hypoxic conditions was dependent on overproduction of mitochondrial reactive oxygen species (mtROS) in cardiomyocytes, and mitochondrial division was identified as the upstream inducer of mtROS overproduction. Silencing mitochondrial division activators, such as B cell receptor associated protein 31 (BAP31) and mitochondrial fission 1 (Fis1), repressed mitochondrial division, thereby inhibiting mtROS overproduction and preventing JNK-induced cardiomyocyte death under hypoxic conditions. These data revealed that a novel death-inducing mechanism involving the BAP31/Fis1/mtROS/JNK axis promotes hypoxia-induced cardiomyocyte damage. Considering that BAP31 is localized within the endoplasmic reticulum and Fis1 is localized in mitochondria, abnormal mitochondria-endoplasmic reticulum communication may be a useful therapeutic target after myocardial infarction.

Tracing the NGLY1 footprints: Insights from Drosophila

Recessive mutations in human N-glycanase 1 (NGLY1) cause a multisystem disorder with various phenotypes including global developmental delay. One of the models utilized to understand the biology of NGLY1 and the pathophysiology of NGLY1 deficiency is Drosophila melanogaster, a well-established, genetically tractable organism broadly used to study various biological processes and human diseases. Loss of the Drosophila NGLY1 homolog (Pngl) causes a host of phenotypes including developmental delay and lethality. Phenotypic, transcriptomic and genome-wide association analyses on Drosophila have revealed links between NGLY1 and several critical developmental and cellular pathways/processes. Further, repurposing screens of FDA-approved drugs have identified potential candidates to ameliorate some of the Pngl mutant phenotypes. Here, we will summarize the insights gained into the functions of NGLY1 from Drosophila studies. We hope that the current review article will encourage additional studies in Drosophila and other model systems towards establishing a therapeutic strategy for NGLY1 deficiency patients.

Tubulin binding potentially clears up Bortezomib and Carfilzomib differential neurotoxic effect

Proteasome inhibitors (PIs) represent the gold standard in the treatment of multiple myeloma. Among PIs, Bortezomib (BTZ) is frequently used as first line therapy, but peripheral neuropathy (PN), occurring approximately in 50% of patients, impairs their life, representing a dose-limiting toxicity. Carfilzomib (CFZ), a second-generation PI, induces a significantly less severe PN. We investigated possible BTZ and CFZ off-targets able to explain their different neurotoxicity profiles. In order to identify the possible PIs off-targets we used the SPILLO-PBSS software that performs a structure-based in silico screening on a proteome-wide scale. Among the top-ranked off-targets of BTZ identified by SPILLO-PBSS we focused on tubulin which, by contrast, did not turn out to be an off-target of CFZ. We tested the hypothesis that the direct interaction between BTZ and microtubules would inhibit the tubulin alfa GTPase activity, thus reducing the microtubule catastrophe and consequently furthering the microtubules polymerization. This hypothesis was validated in a cell-free model, since BTZ (but not CFZ) reduces the concentration of the free phosphate released during GTP hydrolysis. Moreover, NMR binding studies clearly demonstrated that BTZ, unlike CFZ, is able to interact with both tubulin dimers and polymerized form. Our data suggest that different BTZ and CFZ neurotoxicity profiles are independent from their proteasome inhibition, as demonstrated in adult mice dorsal root ganglia primary sensory neurons, and, first, we demonstrate, in a cell free model, that BTZ is able to directly bind and perturb microtubules.

Pathological Mechanisms of Bortezomib-Induced Peripheral Neuropathy

Bortezomib, a first-generation proteasome inhibitor widely used in chemotherapy for hematologic malignancy, has effective anti-cancer activity but often causes severe peripheral neuropathy. Although bortezomib-induced peripheral neuropathy (BIPN) is a dose-limiting toxicity, there are no recommended therapeutics for its prevention or treatment. One of the most critical problems is a lack of knowledge about pathological mechanisms of BIPN. Here, we summarize the known mechanisms of BIPN based on preclinical evidence, including morphological abnormalities, involvement of non-neuronal cells, oxidative stress, and alterations of transcriptional programs in both the peripheral and central nervous systems. Moreover, we describe the necessity of advancing studies that identify the potential efficacy of approved drugs on the basis of pathological mechanisms, as this is a convincing strategy for rapid translation to patients with cancer and BIPN.

Non-Hematologic Toxicity of Bortezomib in Multiple Myeloma: The Neuromuscular and Cardiovascular Adverse Effects

Simple Summary

Multiple myeloma (MM) is a still uncurable tumor of mainly elderly patients originating from the terminally differentiated B cells. Introduction to the treatment of MM patients of a new class of drugs called proteasome inhibitors (bortezomib followed by carfilzomib and ixazomib) significantly improved disease control. Proteasome inhibitors interfere with the major mechanism of protein degradation in a cell leading to the severe imbalance in the protein turnover that is deadly to MM cells. Currently, these drugs are the mainstream of MM therapy but are also associated with an increased rate of the injuries to multiple organs and tissues. In this review, we summarize the current knowledge on the molecular mechanisms of the first-in-class proteasome inhibitor bortezomib-induced disturbances in the function of peripheral nerves and cardiac and skeletal muscle.

Abstract

The overall approach to the treatment of multiple myeloma (MM) has undergone several changes during the past decade. and proteasome inhibitors (PIs) including bortezomib, carfilzomib, and ixazomib have considerably improved the outcomes in affected patients. The first-in-class selective PI bortezomib has been initially approved for the refractory forms of the disease but has now become, in combination with other drugs, the backbone of the frontline therapy for newly diagnosed MM patients, as well as in the maintenance therapy and relapsed/refractory setting. Despite being among the most widely used and highly effective agents for MM, bortezomib can induce adverse events that potentially lead to early discontinuation of the therapy with negative effects on the quality of life and outcome of the patients. Although peripheral neuropathy and myelosuppression have been recognized as the most relevant bortezomib-related adverse effects, cardiac and skeletal muscle toxicities are relatively common in MM treated patients, but they have received much less attention. Here we review the neuromuscular and cardiovascular side effects of bortezomib. focusing on the molecular mechanisms underlying its toxicity. We also discuss our preliminary data on the effects of bortezomib on skeletal muscle tissue in mice receiving the drug.