The proteasome: a suitable antineoplastic target

Proteasome inhibition induces apoptosis through simultaneous inactivation of MCL-1/BCL-XL by NOXA independent of CHOP and JNK pathways

Proteasome inhibitors have been employed in the treatment of relapsed multiple myeloma and mantle cell lymphoma. The observed toxicity caused by proteasome inhibitors is a universal phenotype in numerous cancer cells with different sensitivity. In this study, we investigate the conserved mechanisms underlying the toxicity of the proteasome inhibitor bortezomib using gene editing approaches. Our findings utilizing different caspase knocking out cells reveal that bortezomib induces classic intrinsic apoptosis by activating caspase-9 and caspase-3/7, leading to pore-forming protein GSDME cleavage and subsequent lytic cell death or called secondary necrosis, a phenotype also observed in many apoptosis triggers like TNFα plus CHX, DTT and tunicamycin treatment in HeLa cells. Furthermore, through knocking out of nearly all BH3-only proteins including BIM, BAD, BID, BMF and PUMA, we demonstrate that NOXA is the sole BH3-only protein responsible for bortezomib-induced apoptosis. Of note, NOXA is well known for selectively binding to MCL-1 and A1, but our studies utilizing different BH3 mimetics as well as immunoprecipitation assays indicate that, except for the constitutive interaction of NOXA with MCL-1, the accumulation of NOXA after bortezomib treatment allows it to interact with BCL-XL, then simultaneous relieving suppression on apoptosis by both anti-apoptotic proteins BCL-XL and MCL-1. In addition, though bortezomib-induced significant ER stress and JNK activation were observed in the study, further genetic depletion experiments prove that bortezomib-induced apoptosis occurs independently of ER stress-related apoptosis factor CHOP and JNK. In summary, these results provide a solid conclusion about the critical role of NOXA in inactivation of BCL-XL except MCL-1 in bortezomib-induced apoptosis.

Loss of heterozygosity of CYP2D6 enhances the sensitivity of hepatocellular carcinomas to talazoparib

BACKGROUND

Loss of heterozygosity (LOH) diminishes genetic diversity within cancer genomes. A tumour arising in an individual heterozygous for a functional and a loss-of-function (LoF) allele of a gene occasionally retain only the LoF allele. This can result in deficiency of specific protein activities in cancer cells, creating unique differences between tumour cells and normal cells of the individual. Such differences may constitute vulnerabilities that can be exploited through allele-specific therapies.

METHODS

To discover frequently lost genes with prevalent LoF alleles, we mined the 1000 Genomes dataset for SNVs causing protein truncation through base substitution, indels or splice site disruptions, resulting in 60 LoF variants in 60 genes. From these, the variant rs3892097 in the liver enzyme CYP2D6 was selected because it is located within a genomic region that frequently undergoes LOH in several tumor types including hepatocellular cancers. To evaluate the relationship between CYP2D6 activity and the toxicities of anticancer agents, we screened 525 compounds currently in clinical use or undergoing clinical trials using cell model systems with or without CYP2D6 activity.

FINDINGS

We identified 12 compounds, AZD-3463, CYC-116, etoposide, everolimus, GDC-0349, lenvatinib, MK-8776, PHA-680632, talazoparib, tyrphostin 9, VX-702, and WZ-3146, using an engineered HEK293T cell model. Of these, talazoparib and MK-8776 demonstrated consistently heightened cytotoxic effects against cells with compromised CYP2D6 activity in engineered hepatocellular cancer cell models. Moreover, talazoparib displayed CYP2D6 genotype dependent effects on primary hepatocellular carcinoma organoids.

INTERPRETATION

Exploiting the loss of drug-metabolizing enzyme gene activity in tumor cells following loss of heterozygosity could present a promising therapeutic strategy for targeted cancer treatment.

FUNDING

This work was funded by Barncancerfonden (T.S, PR2022-0099 and PR2020-0171, X.Z, TJ2021-0111), Cancerfonden (T.S, 211719Pj and D.G, 222449Pj), Vetenskapsrådet (T.S, 2020-02371 and D.G, 2020-04707), and the Erling Persson Foundation (T.S, 2020-0037 and T.S, 2023-0113).

Characterization of driver mutations identifies gene signatures predictive of prognosis and treatment sensitivity in multiple myeloma

In multiple myeloma (MM), while frequent mutations in driver genes are crucial for disease progression, they traditionally offer limited insights into patient prognosis. This study aims to enhance prognostic understanding in MM by analyzing pathway dysregulations in key cancer driver genes, thereby identifying actionable gene signatures. We conducted a detailed quantification of mutations and pathway dysregulations in 10 frequently mutated cancer driver genes in MM to characterize their comprehensive mutational impacts on the whole transcriptome. This was followed by a systematic survival analysis to identify significant gene signatures with enhanced prognostic value. Our systematic analysis highlighted 2 significant signatures, TP53 and LRP1B, which notably outperformed mere mutation status in prognostic predictions. These gene signatures remained prognostically valuable even when accounting for clinical factors, including cytogenetic abnormalities, the International Staging System (ISS), and its revised version (R-ISS). The LRP1B signature effectively distinguished high-risk patients within low/intermediate-risk categories and correlated with significant changes in the tumor immune microenvironment. Additionally, the LRP1B signature showed a strong association with proteasome inhibitor pathways, notably predicting patient responses to bortezomib and the progression from monoclonal gammopathy of unknown significance to MM. Through a rigorous analysis, this study underscores the potential of specific gene signatures in revolutionizing the prognostic landscape of MM, providing novel clinical insights that could influence future translational oncology research.

Analysis of the senescence-associated cell surfaceome reveals potential senotherapeutic targets

The accumulation of senescent cells is thought to play a crucial role in aging-associated physiological decline and the pathogenesis of various age-related pathologies. Targeting senescence-associated cell surface molecules through immunotherapy emerges as a promising avenue for the selective removal of these cells. Despite its potential, a thorough characterization of senescence-specific surface proteins remains to be achieved. Our study addresses this gap by conducting an extensive analysis of the cell surface proteome, or "surfaceome", in senescent cells, spanning various senescence induction regimes and encompassing both murine and human cell types. Utilizing quantitative mass spectrometry, we investigated enriched cell surface proteins across eight distinct models of senescence. Our results uncover significant changes in surfaceome expression profiles during senescence, highlighting extensive modifications in cell mechanics and extracellular matrix remodeling. Our research also reveals substantive heterogeneity of senescence, predominantly influenced by cell type and senescence inducer. A key discovery of our study is the identification of four unique cell surface proteins with extracellular epitopes. These proteins are expressed in senescent cells, absent or present at low levels in their proliferating counterparts, and notably upregulated in tissues from aged mice and an Alzheimer's disease mouse model. These proteins stand out as promising candidates for senotherapeutic targeting, offering potential pathways for the detection and strategic targeting of senescent cell populations in aging and age-related diseases.

Atrial fibrillation in cancer, anticancer therapies, and underlying mechanisms

Atrial fibrillation (AF) is a common arrhythmic complication in cancer patients and can be exacerbated by traditional cytotoxic and targeted anticancer therapies. Increased incidence of AF in cancer patients is independent of confounding factors, including preexisting myocardial arrhythmogenic substrates, type of cancer, or cancer stage. Mechanistically, AF is characterized by fast unsynchronized atrial contractions with rapid ventricular response, which impairs ventricular filling and results in various symptoms such as fatigue, chest pain, and shortness of breath. Due to increased blood stasis, a consequence of both cancer and AF, concern for stroke increases in this patient population. To compound matters, cardiotoxic anticancer therapies themselves promote AF; thereby exacerbating AF morbidity and mortality in cancer patients. In this review, we examine the relationship between AF, cancer, and cardiotoxic anticancer therapies with a focus on the shared molecular and electrophysiological mechanisms linking these disease processes. We also explore the potential role of sodium-glucose co-transporter 2 inhibitors (SGLT2i) in the management of anticancer-therapy-induced AF.

Proteostasis perturbation of N-Myc leveraging HSP70 mediated protein turnover improves treatment of neuroendocrine prostate cancer

N-Myc is a key driver of neuroblastoma and neuroendocrine prostate cancer (NEPC). One potential way to circumvent the challenge of undruggable N-Myc is to target the protein homeostasis (proteostasis) system that maintains N-Myc levels. Here, we identify heat shock protein 70 (HSP70) as a top partner of N-Myc, which binds a conserved "SELILKR" motif and prevents the access of E3 ubiquitin ligase, STIP1 homology and U-box containing protein 1 (STUB1), possibly through steric hindrance. When HSP70's dwell time on N-Myc is increased by treatment with the HSP70 allosteric inhibitor, STUB1 is in close proximity with N-Myc and becomes functional to promote N-Myc ubiquitination on the K416 and K419 sites and forms polyubiquitination chains linked by the K11 and K63 sites. Notably, HSP70 inhibition significantly suppressed NEPC tumor growth, increased the efficacy of aurora kinase A (AURKA) inhibitors, and limited the expression of neuroendocrine-related pathways.

Establishment of a histiocytic sarcoma cell line and anti-tumor effect of bortezomib in the African pygmy hedgehog (Atelerix albiventris)

The African pygmy hedgehog (Atelerix albiventris) is known to have a high incidence of tumor. However, investigating the tumors of this species has been constrained by the limited availability of research materials such as cell lines and genome information. In this study, we successfully established a novel cell line from a histiocytic sarcoma (HS) of an African pygmy hedgehog, allowing us to conduct a drug screening. We investigated using FDA-approved drug library screening to determine which anticancer drug this tumor cell line is sensitive to, and as a result of apoptosis experiments, bortezomib among the three proteasome inhibitors was found to induce cell death of cancer cells by significantly increasing caspase-3 cleavage (P<0.01). Thus, we elucidated that the proteasome inhibitors, particularly bortezomib, exhibit anti-tumor effects on a cell line derived from an HS in an African pygmy hedgehog through a mechanism comparable to that described in human tumors. This study reports the first characterized cell line from the African pygmy hedgehog and also highlights the potential utility of bortezomib as an anti-tumor treatment for HS in this species.

PRAME promotes proliferation of multiple myeloma cells through CTMP/Akt/p21/CCND3 axis by ubiquitinating CTMP and p21

Multiple myeloma (MM) is a Ubiquitin Proteasome System (UPS)-dysfunction disease. We previously reported that high PRAME transcript levels associated with unfavorable progression free survival (PFS) in patients with no bortezomib therapy, and bortezomib-containing regimen significantly improved PFS in patients with high PRAME transcript levels, which indicated that PRAME expression was prognostic for MM patients, and was related to proteasome inhibitor treatment. However, molecular mechanisms underlying the above clinical performance remain unclear. In the present study, MM cell models with PRAME knockdown and overexpression were established, and PRAME was identified to play the role of promoting proliferation in MM cells. P-Akt signaling was found to be activated as PRAME overexpressed. As a substrate recognizing subunit (SRS) of the E3 ubiquitin ligase, PRAME targets substrate proteins and mediates their degradation. CTMP and p21 were found to be the novel targets of PRAME in the Cul2-dependent substrate recognition process. PRAME interacted with and mediated ubiquitination and degradation of CTMP and p21, which led to accumulation of p-Akt and CCND3 proteins, and thus promoted cell proliferation and increased bortezomib sensitivity in MM cells.

Acetaminophen induces mitochondrial apoptosis through proteasome dysfunctions

Acetaminophen is a known antipyretic and non-opioid analgesic for mild pain and fever. Numerous studies uncover their hidden chemotherapeutics applications, including chronic cancer pain management. Acetaminophen also represents an anti-proliferative effect in some cancer cells. Few studies also suggest that the use of Acetaminophen can trigger apoptosis and impede cellular growth. However, Acetaminophen's molecular potential and precise mechanism against improper cellular proliferation and use as an effective anti-proliferative agent still need to be better understood. Here, our current findings show that Acetaminophen induces proteasomal dysfunctions, resulting in aberrant protein accumulation and mitochondrial abnormalities, and consequently induces cell apoptosis. We observed that the Acetaminophen treatment leads to improper aggregation of ubiquitylated expanded polyglutamine proteins, which may be due to the dysfunctions of proteasome activities. Our in-silico analysis suggests the interaction of Acetaminophen and proteasome. Furthermore, we demonstrated the accumulation of proteasome substrates and the depletion of proteasome activities after treating Acetaminophen in cells. Acetaminophen induces proteasome dysfunctions and mitochondrial abnormalities, leading to pro-apoptotic morphological changes and apoptosis successively. These results suggest that Acetaminophen can induce cell death and may retain a promising anti-proliferative effect. These observations can open new possible molecular strategies in the near future for developing and designing specific and effective proteasome inhibitors, which can be helpful in conjugation with other anti-tumor drugs for their better efficiency.

Development of Degraders of Cyclin-Dependent Kinases and Based on Rational Drug Design

Degradation of target proteins has been considered to be a promising therapeutic approach, but the rational design of compounds for degradation remains a challenge. In this study, we reasonably designed and synthesized only 10 compounds to discover effective CDK4/6 protein degraders. Among the newly synthesized compounds, 7f achieved dual degradation of CDK4/6 protein, with DC50 values of 10.5 and 2.5 nM, respectively. Compound 7f also exhibited inhibitory proliferative activity against Jurkat cells with an IC50 value of 0.18 μM. Furthermore, 7f induced cell apoptosis and G1 phase cell cycle arrest in a dose-dependent manner in Jurkat cells. In conclusion, these findings demonstrate the potential of 7f as a CDK4/6 degrader and a potential therapeutic strategy against cancer, thereby expanding the potential of CDK4/6 dual PROTACs.

NF-κB signaling in therapy resistance of breast cancer: Mechanisms, approaches, and challenges

Breast cancer is the most common type of cancer and is the second leading cause of cancer-related mortality in women. Chemotherapy, targeted therapy, endocrine therapy, and radiotherapy are all effective in destroying tumor cells, but they also activate the defense and protection systems of cancer cells, leading to treatment resistance. Breast cancer is characterized by a highly inflammatory tumor microenvironment. The NF-κB pathway is essential for connecting inflammation and cancer, as well as for tumor growth and therapy resistance. An increase in NF-κB signaling boosts the growth potential of breast cancer cells and facilitates the spread of tumors to bone, lymph nodes, lungs, and liver. This review focuses on the mechanisms by which chemotherapy, targeted therapy, endocrine therapy, and radiotherapy induce breast cancer resistance through NF-κB signaling. Additionally, we investigate therapeutic regimens, including single agents or in combination with target inhibitors, plant extracts, nanomedicines, and miRNAs, that have been reported in clinical trials, in vivo, and in vitro to reverse resistance. In particular, NF-κB inhibitors combined with tamoxifen were shown to significantly increase the sensitivity of breast cancer cells to tamoxifen. Combination therapy of miRNA-34a with doxorubicin was also found to synergistically inhibit the progression of doxorubicin-resistant breast cancer by inhibiting Notch/NF-κB signaling.

Updates on the mechanisms of toxicities associated with monoclonal antibodies targeting growth factor signaling and immune cells in cancer

Monoclonal antibody (mAb)-based immunotherapy currently is considered to be an optimal therapeutic approach to cancer treatment, either in combination with surgery, radiation, and/or chemotherapy or alone. Various solid tumors and hematological malignancies have been characterized by distinct molecular targets, which could be utilized as innovative anticancer agents. Notably, receptor tyrosine kinases, including HER2, EGFR, VEGFR, and PDGFR, which act as receptors for growth factors, serve as crucial target proteins, expanding their role in the cancer therapeutic market. In contrast to conventional anticancer agents that directly target cancer cells, the advent of immunotherapy introduces novel approaches, such as immune checkpoint blockers (ICBs) and mAbs targeting surface antigens on immune cells in hematological malignancies and lymphomas. While these immunotherapies have mitigated the acquired resistance observed in traditional targeted therapies, they also exhibit diverse toxicities. Herein, this review focuses on describing the well-established toxicities and newly proposed mechanisms of monoclonal antibody toxicity in recent studies. Understanding these molecular mechanisms is indispensable to overcoming the limitations of mAbs-based therapies, facilitating the development of innovative anticancer agents, and uncovering novel indications for cancer treatment in the future.

A ubiquitin-proteasome system-related signature to predict prognosis, immune infiltration, and therapy efficacy for breast cancer

The ubiquitin-proteasome system (UPS) is an essential regulatory system for maintaining homeostasis, and its dysfunction may cause various diseases. The activity of proteasome and ubiquitin-conjugating enzymes has been found to be greatly increased in breast cancer (BC), indicating that the heterogeneity of UPS may be related to the progression of BC. Gene data was obtained from The Cancer Genome Atlas and Gene Expression Omnibus databases and performed in multiple algorithms to construct a UPS-related signature for BC. Patients in the UPS low-risk group had greater overall and recurrence-free survival probability than those in the UPS high-risk group. This signature was closely associated with functional enrichment. Some high metabolism-related pathways were more active in the UPS high-risk group. The UPS low-risk group had more abundant anti-tumor immune cells, while in the UPS high-risk group, immunosuppressive cells were dominant. More importantly, we found that the UPS low-risk group was more sensitive to immunotherapy, while the UPS high-risk group responded better to radiotherapy. Drug sensitivity analysis identified more effective chemotherapy drugs in different UPS-related risk groups. This UPS-related signature may serve as a novel biomarker and independent prognostic factor for BC. It can effectively predict prognosis, immune infiltration, and therapy efficacy, providing new strategies for individualized treatment.

Acute accumulation of PIM2 and NRF2 and recovery of β5 subunit activity mitigate multiple myeloma cell susceptibility to proteasome inhibitors

Resistance to proteasome inhibitors (PIs) has emerged as an important clinical issue. We investigated the mechanisms underlying multiple myeloma (MM) cell resistance to PIs. To mimic their pharmacokinetic/pharmacodynamic (PK/PD) profiles, MM cells were treated with bortezomib and carfilzomib for 1 h at concentrations up to 400 and 1,000 nM, respectively. Susceptibility to these PIs markedly varied among MM cell lines. Pulsatile treatments with PIs suppressed translation, as demonstrated by incorporation of puromycin at 24 h in PI-susceptible MM.1S cells, but not PI-resistant KMS-11 cells. Inhibition of β5 subunit activity decreased at 24 h in KMS-11 cells, even with the irreversible PI carfilzomib, but not under suppression of protein synthesis with cycloheximide. Furthermore, the proteasome-degradable pro-survival factors PIM2 and NRF2 acutely accumulated in MM cells subjected to pulsatile PI treatments. Accumulated NRF2 was trans-localized into the nucleus to induce the expression of its target gene, HMOX1, in MM cells. PIM and Akt inhibition restored the anti-MM effects of PIs, even against PI-resistant KMS-11 cells. Collectively, these results suggest that increased synthesis of β5 proteasome subunit and acute accumulation of PIM2 and NRF2 reduce the anti-MM effects of PIs.

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.

Comprehensive analysis of PSMD family members and validation of PSMD9 as a potential therapeutic target in human glioblastoma

AIMS

PSMD family members, as important components of the 26S proteasome, are well known to be involved in protein degradation. However, their role in glioblastoma (GBM) has not been rigorously investigated. We aimed to perform systematic analysis of the expression signature, prognostic significance and functions of PSMD family genes in GBM to reveal potential prognostic markers and new therapeutic targets among PSMD family members.

METHODS

In this study, we systemically analyzed PSMD family members in terms of their expression profiles, prognostic implications, DNA methylation levels, and genetic alterations; the relationships between their expression levels and immune infiltration and drug sensitivity; and their potential functional enrichment in GBM through bioinformatics assessment. Moreover, in vitro and in vivo experiments were used to validate the biological functions of PSMD9 and its targeted therapeutic effect in GBM.

RESULTS

The mRNA levels of PSMD5/8/9/10/11/13/14 were higher in GBM than in normal brain tissues, and the mRNA levels of PSMD1/4/5/8/9/11/12 were higher in high-grade glioma (WHO grade III & IV) than in low-grade glioma (WHO grade II). High mRNA expression of PSMD2/6/8/9/12/13/14 and low mRNA expression of PSMD7 were associated with poor overall survival (OS). Multivariate Cox regression analysis identified PSMD2/5/6/8/9/10/11/12 as independent prognostic factors for OS prediction. In addition, the protein-protein interaction network and gene set enrichment analysis results suggested that PSMD family members and their interacting molecules were involved in the regulation of the cell cycle, cell invasion and migration, and other biological processes in GBM. In addition, knockdown of PSMD9 inhibited cell proliferation, invasion and migration and induced G2/M cell cycle arrest in LN229 and A172 GBM cells. Moreover, PSMD9 promoted the malignant progression of GBM in vivo. GBM cell lines with high PSMD9 expression were more resistant to panobinostat, a potent deacetylase inhibitor, than those with low PSMD9 expression. In vitro and in vivo experiments further validated that PSMD9 overexpression rescued the GBM inhibitory effect of panobinostat.

CONCLUSION

This study provides new insights into the value of the PSMD family in human GBM diagnosis and prognosis evaluation, and we further identified PSMD9 as a potential therapeutic target. These findings may lead to the development of effective therapeutic strategies for GBM.

Boron-containing carbonic anhydrases inhibitors

Over the last decades, the medicinal chemistry of boron-based compounds has been extensively explored, designing valuable small molecule drugs to tackle diseases and conditions, such as cancer, infections, inflammatory and neurological disorders. Notably, boron has proven to also be a valuable element for the development of inhibitors of the metalloenzymes carbonic anhydrases (CAs), a class of drug targets with significant potential in medicinal chemistry. Incorporating boron into carbonic anhydrase inhibitors (CAIs) can modulate the ligand ability to recognize the target and/or influence selectivity towards different CA isoforms, using the tail approach and boron-based tails. The electron-deficient nature of boron and its associated properties have also led to the discovery of novel zinc-binding CAIs, such as boronic acids and the benzoxaboroles, capable of inhibiting the CAs upon a Lewis acid-base mechanism of action. The present manuscript reviews the state-of-the-art of boron-based CAIs. As research in the applications of boron compounds in medicinal chemistry continues, it is anticipated that new boron-based CAIs will soon expand the current array of such compounds. However, further research is imperative to fully unlock the potential of boron-based CAIs and to advance them towards clinical applications.

ByeTAC: Bypassing an E3 Ligase for Targeted Protein Degradation

Targeted protein degradation utilizing a bifunctional molecule to initiate ubiquitination and subsequent degradation by the 26S proteasome has been shown to be a powerful therapeutic intervention. Many bifunctional molecules, including covalent and non-covalent ligands to proteins of interest, have been developed. The traditional target protein degradation methodology targets the protein of interest in both healthy and diseased cell populations, and a therapeutic window is obtained based on the overexpression of the targeted protein. We report here a series of bifunctional degraders that do not rely on interacting with an E3 ligase, but rather a 26S proteasome subunit, which we have named ByeTACs: Bypassing E3 Targeting Chimeras. Rpn-13 is a non-essential ubiquitin receptor for the 26S proteasome. Cells under significant stress or require significant ubiquitin-dependent degradation of proteins for survival, incorporate Rpn-13 in the 26S to increase protein degradation rates. The targeted protein degraders reported here are bifunctional molecules that include a ligand to Rpn-13 and BRD4, the protein of interest we wish to degrade. We synthesized a suite of degraders with varying PEG chain lengths and showed that bifunctional molecules that incorporate a Rpn-13 binder (TCL1) and a BRD4 binder (JQ1) with a PEG linker of 3 or 4 units are the most effective to induce BRD4 degradation. We also demonstrate that our new targeted protein degraders are dependent upon proteasome activity and Rpn-13 expression levels. This establishes a new mechanism of action for our ByeTACs that can be employed for the targeted degradation of a wide variety of protein substrates.

Roles of zinc in cancers: From altered metabolism to therapeutic applications

Zinc (Zn) is a crucial trace element involved in various cellular processes, including oxidative stress, apoptosis and immune response, contributing to cellular homeostasis. Dysregulation of Zn homeostasis occurs in certain cancers. This review discusses the role of Zn in cancer and its associated components, such as Zn-related proteins, their potential as biomarkers and the use of Zn-based strategies for tumor treatment. ZIP and ZnT proteins regulate Zn metabolism under normal conditions, but their expression is aberrant in cancer. These Zn proteins can serve as prognostic or diagnostic biomarkers, aiding in early cancer detection and disease monitoring. Moreover, targeting Zn and its pathways offers potential therapeutic approaches for cancer treatment. Modulating Zn biodistribution within cells using metal-binding agents allows for the control of downstream signaling pathways. Direct utilization of zinc as a therapeutic agent, including Zn supplementation or Zn oxide nanoparticle administration, holds promise for improving the prognosis of cancer patients.

Analysis and experimental validation of the innate immune gene PSMD1 in liver hepatocellular carcinoma and pan-cancer

This work intends to examine the diagnostic, prognostic, and biological roles of PSMD1 (proteasome 26S subunit, non-ATPase 1) in liver hepatocellular carcinoma (LIHC) and other malignancies, using bioinformatics techniques. PSMD1 is an innate immune gene that has been identified as a biomarker for several cancers. By analyzing TCGA data, we determined that PSMD1 has excellent diagnostic and prognostic value in LIHC. We also examined its correlation with stage-matching clinical features, particularly T staging and stage staging. Independent prognostic analysis, nomogram, and Decision Curve Analysis (DCA) analysis confirmed the predictive ability of PSMD1 on patient clinical outcomes. Our focus was on exploring the biological process, immune infiltration, and genetic variation in which PSMD1 is involved in LIHC. We found a close relationship between PSMD1 and the tumor microenvironment (TME), as well as various immune cell infiltration, immune function, and immune checkpoints. Furthermore, our results suggested that liver cancer patients with low PSMD1 expression were more actively responsive to immunotherapy according to TIDE predictions. Additionally, we observed significant differences in patient survival based on the different immune molecular types of tumors and their correlation with PSMD1 expression. The close relationship between PSMD1 and copy number variation (CNV), tumor mutational burden (TMB), and methylation was also confirmed, showing a significant impact on patient survival. Moreover, the pan-cancer analysis revealed that PSMD1 is closely related to the diagnosis and prognosis of various cancers, as well as immune infiltration across different cancer types. In summary, PSMD1 has the potential to be a useful diagnostic and prognostic biomarker for LIHC and other types of cancers. It is closely associated with indicators such as immune infiltration, CNV, TMB, and methylation. The identification of PSMD1 may offer a potential intervention target for LIHC and various cancers.

Targeting B cells for treatment of systemic sclerosis

PURPOSE OF REVIEW

The pathogenesis of systemic sclerosis (SSc) has been linked to dysfunctional B cells as demonstrated in previous research. This review aims to show the evidence and ongoing clinical trials of B cell-targeted therapy and overview the various aspects of B cell involvement in SSc.

RECENT FINDINGS

We provide an overview of the current understanding and therapeutic strategies targeting B cells in SSc patients. Several molecular targets of B cells have been identified for treating SSc, including CD20, CD19, B-cell activating factor (BAFF), and proteasome.

SUMMARY

Many clinical trials have demonstrated that B cells play a critical role in the pathogenesis of SSc and may be a potential therapeutic target to improve disease symptoms. Although large-scale clinical studies are needed, various B cell-targeted therapies have the potential to address the unmet needs of SSc patients.

Roles and Molecular Mechanisms of Biomarkers in Hepatocellular Carcinoma with Microvascular Invasion: A Review

Hepatocellular carcinoma (HCC) being a leading cause of cancer-related death, has high associated mortality and recurrence rates. It has been of great necessity and urgency to find effective HCC diagnosis and treatment measures. Studies have shown that microvascular invasion (MVI) is an independent risk factor for poor prognosis after hepatectomy. The abnormal expression of biomacromolecules such as circ-RNAs, lncRNAs, STIP1, and PD-L1 in HCC patients is strongly correlated with MVI. Deregulation of several markers mentioned in this review affects the proliferation, invasion, metastasis, EMT, and anti-apoptotic processes of HCC cells through multiple complex mechanisms. Therefore, these biomarkers may have an important clinical role and serve as promising interventional targets for HCC. In this review, we provide a comprehensive overview on the functions and regulatory mechanisms of MVI-related biomarkers in HCC.

Novel Therapeutic Strategies in the Treatment of Systemic Sclerosis

Systemic sclerosis is a connective tissue disease of unknown origin and with an unpredictable course, with both cutaneous and internal organ manifestations. Despite the enormous progress in rheumatology and clinical immunology, the background of this disease is largely unknown, and no specific therapy exists. The therapeutic approach aims to treat and preserve the function of internal organs, and this approach is commonly referred to as organ-based treatment. However, in modern times, data from other branches of medicine may offer insight into how to treat disease-related complications, making it possible to find new drugs to treat this disease. In this review, we present therapeutic options aiming to stop the progression of fibrotic processes, restore the aberrant immune response, stop improper signalling from proinflammatory cytokines, and halt the production of disease-related autoantibodies.

The Potential of Cylindromatosis (CYLD) as a Therapeutic Target in Oxidative Stress-Associated Pathologies: A Comprehensive Evaluation

Oxidative stress (OS) arises as a consequence of an imbalance between the formation of reactive oxygen species (ROS) and the capacity of antioxidant defense mechanisms to neutralize them. Excessive ROS production can lead to the damage of critical biomolecules, such as lipids, proteins, and DNA, ultimately contributing to the onset and progression of a multitude of diseases, including atherosclerosis, chronic obstructive pulmonary disease, Alzheimer's disease, and cancer. Cylindromatosis (CYLD), initially identified as a gene linked to familial cylindromatosis, has a well-established and increasingly well-characterized function in tumor inhibition and anti-inflammatory processes. Nevertheless, burgeoning evidence suggests that CYLD, as a conserved deubiquitination enzyme, also plays a pivotal role in various key signaling pathways and is implicated in the pathogenesis of numerous diseases driven by oxidative stress. In this review, we systematically examine the current research on the function and pathogenesis of CYLD in diseases instigated by oxidative stress. Therapeutic interventions targeting CYLD may hold significant promise for the treatment and management of oxidative stress-induced human diseases.

Mechanisms of preferential bone formation in myeloma bone lesions by proteasome inhibitors

Proteasome inhibitors (PIs) can preferentially restore bone in bone-defective lesions of patients with multiple myeloma (MM) who respond favorably to these drugs. Most prior in vitro studies on PIs used continuous exposure to low PI concentrations, although pharmacokinetic analysis in patients has shown that serum concentrations of PIs change in a pulsatile manner. In the present study, we explored the effects of pulsatile treatment with PIs on bone metabolism to simulate in vivo PI pharmacokinetics. Pulsatile treatment with bortezomib, carfilzomib, or ixazomib induced MM cell death but only marginally affected the viability of osteoclasts (OCs) with F-actin ring formation. Pulsatile PI treatment suppressed osteoclastogenesis in OC precursors and bone resorption by mature OCs. OCs robustly enhanced osteoblastogenesis in cocultures with OCs and MC3T3-E1 pre-osteoblastic cells, indicating OC-mediated coupling to osteoblastogenesis. Importantly, pulsatile PI treatment did not impair robust OC-mediated osteoblastogenesis. These results suggest that PIs might sufficiently reduce MM cell-derived osteoblastogenesis inhibitors to permit OC-driven bone formation coupling while suppressing OC differentiation and activity in good responders to PIs. OC-mediated coupling to osteoblastogenesis appears to be a predominant mechanism for preferential occurrence of bone regeneration at sites of osteoclastic bone destruction in good responders.

Arginase Inhibition Mitigates Bortezomib-Exacerbated Cardiotoxicity in Multiple Myeloma

BACKGROUND

Multiple myeloma (MM) is associated with increased cardiovascular morbidity and mortality, while MM therapies also result in adverse cardiac effects. Endothelial dysfunction and impaired nitric oxide (NO) pathway is their possible mediator.

OBJECTIVE

Since MM is associated with increased arginase expression, resulting in the consumption of ʟ-arginine, precursor for NO synthesis, our aim was to test if cardiotoxicity mediated by MM and MM therapeutic, bortezomib (a proteasome inhibitor), can be ameliorated by an arginase inhibitor through improved endothelial function.

METHODS

We used a mouse Vĸ*MYC model of non-light chain MM. Cardiac function was assessed by echocardiography.

RESULTS

MM resulted in progressive left ventricular (LV) systolic dysfunction, and bortezomib exacerbated this effect, leading to significant impairment of LV performance. An arginase inhibitor, OAT-1746, protected the heart against bortezomib- or MM-induced toxicity but did not completely prevent the effects of the MM+bortezomib combination. MM was associated with improved endothelial function (assessed as NO production) vs. healthy controls, while bortezomib did not affect it. OAT-1746 improved endothelial function only in healthy mice. NO plasma concentration was increased by OAT-1746 but was not affected by MM or bortezomib.

CONCLUSIONS

Bortezomib exacerbates MM-mediated LV systolic dysfunction in a mouse model of MM, while an arginase inhibitor partially prevents it. Endothelium does not mediate either these adverse or beneficial effects. This suggests that proteasome inhibitors should be used with caution in patients with advanced myeloma, where the summation of cardiotoxicity could be expected. Therapies aimed at the NO pathway, in particular arginase inhibitors, could offer promise in the prevention/treatment of cardiotoxicity in MM.

Biomedical importance of the ubiquitin-proteasome system in diabetes and metabolic transdifferentiation of pancreatic duct epithelial cells into β-cells

The ubiquitin-proteasome system (UPS) is a major pathway for cellular protein degradation. The molecular function of the UPS is the removal of damaged proteins, and this function is applied in many biological processes, including inflammation, proliferation, and apoptosis. Accumulating evidence also suggests that the UPS also has a key role in pancreatic β-cell transdifferentiation in diabetes and can be targeted for treatment of diabetic diseases. In this review, we summarized the mechanistic roles of the UPS in the biochemical activities of pancreatic β-cells, including the role of the UPS in insulin synthesis and secretion, as well as β-cell degradation. Also, we discuss how the UPS mediates the transdifferentiation of pancreatic duct epithelial cells into β-cells as the experimental basis for the development of new strategies for the treatment of diabetes in regenerative medicine.

Recent Advances and Future Perspectives of Noncompetitive Proteasome Inhibitors

The proteasome regulates intracellular processes, maintains biological homeostasis, and has shown great significance in the study of various diseases, such as neurodegenerative diseases, immune-related diseases, and cancer, especially in hematologic malignancies such as multiple myeloma (MM) and mantle cell lymphoma (MCL). All clinically used proteasome inhibitors bind to the active site of the proteasome and thus exhibit a competitive mechanism. The development of resistance and intolerance during treatment drives the search for inhibitors with different mechanisms of action. In this review, we provide an overview of noncompetitive proteasome inhibitors, including their mechanisms of action, function, possible applications, and their advantages and disadvantages compared with competitive inhibitors.

Pharmacological inhibition of the ubiquitin-specific protease 8 effectively suppresses glioblastoma cell growth

Glioblastoma (GBM) is a malignant brain tumor. The purpose of this study is to estimate the potential effects and underlying mechanisms of a ubiquitin-specific protease 8 (USP8) small-molecule inhibitor on the phenotypic characteristics of GBM cells. The growth, migration, invasion, and stemness of GBM LN229 and T98G cells were evaluated by conducting cell proliferation, colony formation, wound healing, transwell, Ki-67 staining, spheroid formation, and ionizing radiation assays, and the results collectively showed the suppressive effects of USP8 inhibition on GBM cells. Furthermore, transcriptomic profiling of GBM cells treated with the USP8 inhibitor deubiquitinase (DUB)-IN-1 revealed significantly altered mRNA expression induced by pharmacological USP8 inhibition, from which we confirmed downregulated Aurora kinase A (AURKA) protein levels using immunoblotting assays. Our findings indicated that the proliferation, invasion, and stemness of LN229 and T98G cells were markedly suppressed by USP8 inhibition. Pharmacological USP8 suppression elicits multiple tumor-inhibitory effects, likely through dysregulating various mRNA expression events, including that of the key cell cycle regulator and oncogenic protein AURKA. Therefore, our observations corroborate the GBM-supportive roles of USP8 and suggest pharmacological USP8 inhibition is a viable therapeutic approach to target GBM. The purpose of this study was to investigate the effect and mechanism of action of the USP8 inhibitor DUB-IN-1 on GBM.

Autophagy/Mitophagy Regulated by Ubiquitination: A Promising Pathway in Cancer Therapeutics

Autophagy is essential for organismal development, maintenance of energy homeostasis, and quality control of organelles and proteins. As a selective form of autophagy, mitophagy is necessary for effectively eliminating dysfunctional mitochondria. Both autophagy and mitophagy are linked with tumor progression and inhibition. The regulation of mitophagy and autophagy depend upon tumor type and stage. In tumors, mitophagy has dual roles: it removes damaged mitochondria to maintain healthy mitochondria and energy production, which are necessary for tumor growth. In contrast, mitophagy has been shown to inhibit tumor growth by mitigating excessive ROS production, thus preventing mutation and chromosomal instability. Ubiquitination and deubiquitination are important modifications that regulate autophagy. Multiple E3 ubiquitin ligases and DUBs modulate the activity of the autophagy and mitophagy machinery, thereby influencing cancer progression. In this review, we summarize the mechanistic association between cancer development and autophagy/mitophagy activities regulated by the ubiquitin modification of autophagic proteins. In addition, we discuss the function of multiple proteins involved in autophagy/mitophagy in tumors that may represent potential therapeutic targets.

Discovery of Highly Selective Inhibitors of the Human Constitutive Proteasome β5c Chymotryptic Subunit

We describe our discovery and development of potent and highly selective inhibitors of human constitutive proteasome chymotryptic activity (β5c). Structure-activity relationship studies of the novel class of inhibitors focused on optimization of N-cap, C-cap, and side chain of the chemophore asparagine. Compound 32 is the most potent and selective β5c inhibitor in this study. A docking study provides a structure rationale for potency and selectivity. Kinetic studies show a reversible and noncompetitive inhibition mechanism. It enters the cells to engage the proteasome target, potently and selectively kills multiple myeloma cells, and does so by synergizing with a β5i-selective inhibitor.

Electronic and structural study of T315I mutated form in DFG-out conformation of BCR-ABL inhibitors

In this work, the four main drugs for the treatment of chronic myeloid leukemia were analyzed, being imatinib, dasatinib, nilotinib and ponatinib followed by four derivative molecules of nilotinib and ponatinib. For these derivative molecules, the fluorine atoms were replaced by hydrogen and chlorine atoms in order to shade light to the structural effects on this set of inhibitors. Electronic studies were performed at density functional theory level with the B3LYP functional and 6-311+G(d,p) basis set. The frontier molecular orbitals, gap HOMO-LUMO, and NBO were analyzed and compared to docking studies for mutant T315I tyrosine kinase protein structure code 3IK3, in the DFG-out conformation. Structural similarities were pointed out, such as the presence of groups common to all inhibitors and modifications raised up on new generations of imatinib-based inhibitors. One of them is the trifluoromethyl group present in nilotinib and later included in ponatinib, in addition to the 1-methylpiperazin-1-ium group that is present in imatinib and ponatinib. The frontier molecular orbitals of imatinib and ponatinib are contributing to the same amino acid residues, and the ineffectiveness of imatinib against the T315I mutation was discussed.Communicated by Ramaswamy H. Sarma.

Functional and quantitative evaluation of the 20S proteasome in serum and intracellular in145 moroccan patients with hematologic malignancies

BACKGROUND

Regulatory degradation of intracellular proteins plays an essential role in most biological processes, particularly in the control of cell proliferation and differentiation. In eukaryotes, intracellular proteolysis is largely provided by the Ubiquitin / Proteasome system. Alterations and dysfunction of protein degradation by the Ubiquitin / Proteasome system, such as transcription factors, cell cycle regulators or tumor suppressor proteins, have been linked to human. Pathologies, including blood cancers. Mainly localized in the nucleus and cytoplasm of cells, the proteasome can be detected in the cell culture supernatant or in the peripheral blood of patients. This study deals with the problems of the search for serum markers specific to certain pathologies and which would be useful in the prevention, diagnosis and monitoring of cancers and which could be used as a therapeutic tool.

METHODS

The functional and quantitative analysis of the proteasome is carried out at the serum and subcellular level during a pathological phenomenon in a population of 145 Moroccan patients (sex ratio: 1.10 / average age: 47.9 ± 15, 3 years) using an indirect ELISA test and a follow-up of the fluorescence emitted after enzymatic digestion of specific peptides by proteolytic activity (chymotrypsin-like).

RESULTS

The evolutionary trend proteasome subcellular is significantly linked to the rate of chymotrypsin-like activity. The entire population of 60 patients called back for a second blood test. After three months of treatment reported a significant drop in the rate and the activity of the proteasome in serum and intracellular level.

CONCLUSIONS

Although the serum proteasome level is a potential new tool for the monitoring of. Patientswithliquid cancer.

TRIAL REGISTRATION

retrospectively registered.

Potential Therapeutic Effects of Thiazolidinedione on Malignant Glioma

Glioblastoma multiforme (GBM) is the most common and aggressive primary malignant tumor of the central nervous system. GBM has a very low 5-year survival rate and reaching merely a median of ~15 months even with aggressive treatments. PPARγ (Peroxisome proliferator- activated receptor gamma) agonists (ciglitazone), while being widely used on patients of type 2 diabetes mellitus, also have approved anticancer effects. Their action mechanisms on malignant glioma are not fully understood. The aim of this study is to investigate the potential therapeutic effect of PPARγ agonists on maligant glioma. Glioma cell line and in-vivo/ex-vivo animal model intervened by ciglitazone were used to assess the associated mechanism and therapeutic effect. Our results from in vivo and ex vivo experiments showed that ciglitazone not only inhibited tumor growth and its associated angiogenesis, but it also reduced colony formation and migration of tumors. Ciglitazone inhibited the phosphorylation of STAT3 (signal transducer and activator of transcription 3) (at the point of tyrosine 705 by increasing both the amount and activity of SHP-2 (Src homology region 2-containing protein tyrosine phosphatase 2) proteins, based on evidence obtained from immunoprecipitation and immunohistochemistry. Furthermore, ciglitazone activated proteasomes and lysosomes to degrade cell-cycle-related proteins like Cyclin D1, Cyclin E, CDK2 (Cyclin-dependent kinase 2), and CDK4 (Cyclin-dependent kinase 4). Ciglitazone triggered expressions of LC3 (Microtubule-associated protein 1A/1B-light chain 3) and formation of acidic vesicular organelles (AVOs), both of which were implicated in the autophagy pathway. In conclusion, ciglitazone showed the multiple actions to regulate the growth of glioma, which appeared to be a potential candidate for treating malignant glioma.

MLN2238 exerts its anti-tumor effects via regulating ROS/JNK/mitochondrial signaling pathways in intrahepatic cholangiocarcinoma

Background: Intrahepatic Cholangiocarcinoma (iCCA) is a highly malignant tumor with limited treatment options that contributes largely to cancer-related deaths worldwide. Compared with traditional transcriptomic analysis, single-cell RNA sequencing (scRNA-seq) is emerging as a more advanced and popular tool for the in-depth exploration of cellular diversity and molecular complexity. As a next-generation proteasome inhibitor, MLN2238 presents better pharmacodynamics, pharmacokinetics, and therapeutic responses in various cancers. However, its effects and mechanisms of action in iCCA remain unknown. Methods: iCCA tumor heterogeneity was determined based on 4,239 qualified scRNA-seq data from 10 iCCA samples. The potential biological roles of proteasome-related genes in iCCA were investigated using a pseudo-trajectory reconstruction. The effect of MLN2238 on iCCA cell proliferation was estimated using the CCK-8, EdU, and clone formation assays. Flow cytometry was used to examine the effect of added MLN2238 on cell cycle and apoptosis levels. Autophagic flux was detected using AdPlus-mCherry-GFP-LC3B cells. ROS levels and mitochondrial membrane potential were determined using DCFH-DA probing and JC-1 staining. JNK activation and mitochondrial apoptosis were observed using western blotting and immunofluorescence microscopy, respectively. Finally, we used a tumor-bearing mouse model to validate its efficacy in vivo for iCCA treatment. Results: Proteasome-related genes were dysregulated in iCCA progression and expressed at higher levels in tumor tissues. MLN2238 suppressed cell proliferation, blocked the cell cycle in the G2/M phase, promoted apoptosis, and induced cytoprotective autophagy in iCCA cells. Furthermore, MLN2238 increased ROS levels and activated the JNK signaling pathway. Inhibition of ROS and JNK activation by NAC and SP600125 significantly reversed MLN2238-induced apoptosis. MLN2238 also suppressed the growth of iCCA tumors in vivo. Conclusion: Proteasome-related genes play pivotal roles in iCCA development. MLN2238, as a proteasome inhibitor, induces apoptosis in iCCA cells through ROS/JNK/mitochondrial signaling pathways, and hence, making MLN2238 a potential therapeutic choice for iCCA.

Cystargolide-based amide and ester Pz analogues as proteasome inhibitors and anti-cancer agents

A series of cystargolide-based β-lactone analogues containing nitrogen atoms at the Pz portion of the scaffold were prepared and evaluated as proteasome inhibitors, and for their cytotoxicity profile toward several cancer cell lines. Inclusion of one, two or even three nitrogen atoms at the Pz portion of the cystargolide scaffold is well tolerated, producing analogues with low nanomolar proteasome inhibition activity, in many cases superior to carfilzomib. Additionally, analogue 8g, containing an ester and pyrazine group at Pz, was shown to possess significant activity toward RPMI 8226 cells (IC₅₀ = 21 nM) and to be less cytotoxic toward the normal tissue model MCF10A cells than carfilzomib.

Kinase Inhibition in Multiple Myeloma: Current Scenario and Clinical Perspectives

Multiple myeloma (MM) is a blood cell neoplasm characterized by excessive production of malignant monoclonal plasma cells (activated B lymphocytes) by the bone marrow, which end up synthesizing antibodies or antibody fragments, called M proteins, in excess. The accumulation of this production, both cells themselves and of the immunoglobulins, causes a series of problems for the patient, of a systemic and local nature, such as blood hyperviscosity, renal failure, anemia, bone lesions, and infections due to compromised immunity. MM is the third most common hematological neoplasm, constituting 1% of all cancer cases, and is a disease that is difficult to treat, still being considered an incurable disease. The treatments currently available cannot cure the patient, but only extend their lifespan, and the main and most effective alternative is autologous hematopoietic stem cell transplantation, but not every patient is eligible, often due to age and pre-existing comorbidities. In this context, the search for new therapies that can bring better results to patients is of utmost importance. Protein tyrosine kinases (PTKs) are involved in several biological processes, such as cell growth regulation and proliferation, thus, mutations that affect their functionality can have a great impact on crucial molecular pathways in the cells, leading to tumorigenesis. In the past couple of decades, the use of small-molecule inhibitors, which include tyrosine kinase inhibitors (TKIs), has been a hallmark in the treatment of hematological malignancies, and MM patients may also benefit from TKI-based treatment strategies. In this review, we seek to understand the applicability of TKIs used in MM clinical trials in the last 10 years.

Identification of a drug-response gene in multiple myeloma through longitudinal single-cell transcriptome sequencing

Despite recent therapeutic advances for multiple myeloma (MM), relapse is very common. Here, we conducted longitudinal single-cell transcriptome sequencing (scRNA-seq) of MM cells from a patient with relapsed MM, treated with multiple anti-myeloma drugs. We observed five subclusters of MM cells, which appeared and/or disappeared in response to the therapeutic pressure, and identified cluster 3 which emerged during lenalidomide treatment and disappeared after proteasome inhibitor (PI) treatment. Among the differentially expressed genes in cluster 3, we found a candidate drug-response gene; pellino E3 ubiquitin-protein ligase family member 2 (PELI2), which is responsible for PI-induced cell death in in vitro assay. Kaplan-Meier survival analysis of database revealed that higher expression of PELI2 is associated with a better prognosis. Our integrated strategy combining longitudinal scRNA-seq analysis, in vitro functional assay, and database analysis would facilitate the understanding of clonal dynamics of MM in response to anti-myeloma drugs and identification of drug-response genes.

Design, Synthesis, and Optimization of Macrocyclic Peptides as Species-Selective Antimalaria Proteasome Inhibitors

With over 200 million cases and close to half a million deaths each year, malaria is a threat to global health, particularly in developing countries. Plasmodium falciparum, the parasite that causes the most severe form of the disease, has developed resistance to all antimalarial drugs. Resistance to the first-line antimalarial artemisinin and to artemisinin combination therapies is widespread in Southeast Asia and is emerging in sub-Saharan Africa. The P. falciparum proteasome is an attractive antimalarial target because its inhibition kills the parasite at multiple stages of its life cycle and restores artemisinin sensitivity in parasites that have become resistant through mutation in Kelch K13. Here, we detail our efforts to develop noncovalent, macrocyclic peptide malaria proteasome inhibitors, guided by structural analysis and pharmacokinetic properties, leading to a potent, species-selective, metabolically stable inhibitor.

Development of a high-throughput assay to identify inhibitors of the ubiquitin-conjugating enzyme UBCH10

UBCH10 is an ubiquitin-conjugating enzyme (E2) of the anaphase-promoting complex E3 ligase, a key regulator of the cell cycle. The UBCH10 gene and protein are frequently upregulated in multiple solid tumors, associated with an unfavorable outcome. Accumulating evidence from studies of human cancer cell lines, mouse transgenic models, and analyses of clinical samples suggest that UBCH10 is a potential cancer drug target. No small molecule inhibitor of UBCH10 has been reported in the literature. Here, we described the development and optimization of a novel time-resolved fluorescence resonance energy transfer (TR-FRET) UBCH10 assay based on the self-polyubiquitination of the enzyme in the absence of E3. The homogenous assay is robust, sensitive, and scalable to different multi-well formats for high-throughput screening (HTS). We demonstrate the suitability of the TR-FRET assay to identify chemical inhibitors of UBCH10 in a pilot HTS campaign.

Metformin Induces Resistance of Cancer Cells to the Proteasome Inhibitor Bortezomib

The anti-diabetic drug metformin is currently tested for the treatment of hematological and solid cancers. Proteasome inhibitors, e.g., Bortezomib, are approved for the treatment of multiple myeloma and mantle cell lymphoma but are also studied for lung cancer therapy. We here analyzed the interaction of the two drugs in two cell lines, namely the mantle cell lymphoma Jeko-1 and the non-small-cell lung cancer (NSCLC) H1299 cells, using proliferation and survival assays, native-gel analysis for proteasome activity and assembly, and expression analysis of proteasome assembly factors. Our results demonstrate that metformin treatment induces resistance of cancer cells to the proteasome inhibitor Bortezomib by impairing the activity and assembly of the 26S proteasome complexes. These effects of metformin on proteasome inhibitor sensitivity in cancer cells are of potential relevance for patients that receive proteasome inhibitor therapy.

Proteomic Assessment of Extracellular Vesicles from Canine Tissue Explants as a Pipeline to Identify Molecular Targets in Osteosarcoma: PSMD14/Rpn11 as a Proof of Principle

Osteosarcoma (OS) is a highly malignant bone tumour that has seen little improvement in treatment modalities in the past 30 years. Understanding what molecules contribute to OS biology could aid in the discovery of novel therapies. Extracellular vesicles (EVs) serve as a mode of cell-to-cell communication and have the potential to uncover novel protein signatures. In our research, we developed a novel pipeline to isolate, characterize, and profile EVs from normal bone and osteosarcoma tissue explants from canine OS patients. Proteomic analysis of vesicle preparations revealed a protein signature related to protein metabolism. One molecule of interest, PSMD14/Rpn11, was explored further given its prognostic potential in human and canine OS, and its targetability with the drug capzimin. In vitro experiments demonstrated that capzimin induces apoptosis and reduces clonogenic survival, proliferation, and migration in two metastatic canine OS cell lines. Capzimin also reduces the viability of metastatic human OS cells cultured under 3D conditions that mimic the growth of OS cells at secondary sites. This unique pipeline can improve our understanding of OS biology and identify new prognostic markers and molecular targets for both canine and human OS patients.

Promising therapeutic approaches for relapsed/refractory multiple myeloma

OBJECTIVE

Treatment strategies for relapsed/refractory MM are particularly complex. In particular, patients who are refractory to the three classes of therapies have limited therapeutic options and poor survival. Fortunately, promising treatments are emerging, but their incorporation into existing treatments still needs to be defined. We will describe the latest trends and emerging developments in the field of therapies for RRMM by analyzing the most recent clinical data and new technologies in drug development.

METHODS

Pubmed, Embase and Cochrane Library were searched to select eligible studies, the clinical data of new promising treatments were reviewed. The key results of the most recent clinical trial were summarized in Table.

RESULTS

A total of 13 studies were included in the final analysis involving anti-BCMA CAR T-cell therapy, Combined CAR T-cell therapy, antibody-drug conjugates, bispecific Ab therapy and CELMoDs. The key efficacy and side effects of treatments were summarized.

CONCLUSIONS

There is great promise for a set of next-generation of rescue therapies, including CAR T-cell therapy, bispecific antibodies, antibody-drug conjugates, and novel PROteolysis Targeting Chimeras. Emerging new treatments for MM provide more choices for relapsed/refractory multiple myeloma (RRMM). The optimal therapy for each patient should be based on disease-related factors, such as previous therapies, duration of response to prior drugs, clinical and biochemical features of relapse, and the relationship of patient comorbidities with known AE profiles of the different therapies.

Once weekly selinexor, carfilzomib and dexamethasone in carfilzomib non-refractory multiple myeloma patients

BACKGROUND

Proteasome inhibitors (PIs), including carfilzomib, potentiate the activity of selinexor, a novel, first-in-class, oral selective inhibitor of nuclear export (SINE) compound, in preclinical models of multiple myeloma (MM).

METHODS

The safety, efficacy, maximum-tolerated dose (MTD) and recommended phase 2 dose (RP2D) of selinexor (80 or 100 mg) + carfilzomib (56 or 70 mg/m2) + dexamethasone (40 mg) (XKd) once weekly (QW) was evaluated in patients with relapsed refractory MM (RRMM) not refractory to carfilzomib.

RESULTS

Thirty-two patients, median prior therapies 4 (range, 1-8), were enrolled. MM was triple-class refractory in 38% of patients and 53% of patients had high-risk cytogenetics del(17p), t(4;14), t(14;16) and/or gain 1q. Common treatment-related adverse events (all/Grade 3) were thrombocytopenia 72%/47% (G3 and G4), nausea 72%/6%, anaemia 53%/19% and fatigue 53%/9%, all expected and manageable with supportive care and dose modifications. MTD and RP2D were identified as selinexor 80 mg, carfilzomib 56 mg/m2, and dexamethasone 40 mg, all QW. The overall response rate was 78% including 14 (44%) ≥ very good partial responses. Median progression-free survival was 15 months.

CONCLUSIONS

Weekly XKd is highly effective and well-tolerated. These data support further investigation of XKd in patients with MM.

Spatiotemporal Activation of Protein O-GlcNAcylation in Living Cells

O-linked N-acetylglucosamine (O-GlcNAc) is a prevalent protein modification that plays fundamental roles in both cell physiology and pathology. O-GlcNAc is catalyzed solely by O-GlcNAc transferase (OGT). The study of protein O-GlcNAc function is limited by the lack of tools to control OGT activity with spatiotemporal resolution in cells. Here, we report light control of OGT activity in cells by replacing a catalytically essential lysine residue with a genetically encoded photocaged lysine. This enables the expression of a transiently inactivated form of OGT, which can be rapidly reactivated by photo-decaging. We demonstrate the activation of OGT activity by monitoring the time-dependent increase of cellular O-GlcNAc and profile glycoproteins using mass-spectrometry-based quantitative proteomics. We further apply this activation strategy to control the morphological contraction of fibroblasts. Furthermore, we achieved spatial activation of OGT activity predominantly in the cytosol. Thus, our approach provides a valuable chemical tool to control cellular O-GlcNAc with much needed spatiotemporal precision, which aids in a better understanding of O-GlcNAc function.