Protein arginine methyltransferase 3-induced metabolic reprogramming is a vulnerable target of pancreatic cancer

Discovery of PRMT3 Degrader for the Treatment of Acute Leukemia

Protein arginine methyltransferase 3 (PRMT3) plays an important role in gene regulation and a variety of cellular functions, thus, being a long sought-after therapeutic target for human cancers. Although a few PRMT3 inhibitors are developed to prevent the catalytic activity of PRMT3, there is little success in removing the cellular levels of PRMT3-deposited ω-NG,NG-asymmetric dimethylarginine (ADMA) with small molecules. Moreover, the non-enzymatic functions of PRMT3 remain required to be clarified. Here, the development of a first-in-class MDM2-based PRMT3-targeted Proteolysis Targeting Chimeras (PROTACs) 11 that selectively reduced both PRMT3 protein and ADMA is reported. Importantly, 11 inhibited acute leukemia cell growth and is more effective than PRMT3 inhibitor SGC707. Mechanism study shows that 11 induced global gene expression changes, including the activation of intrinsic apoptosis and endoplasmic reticulum stress signaling pathways, and the downregulation of E2F, MYC, oxidative phosphorylation pathways. Significantly, the combination of 11 and glycolysis inhibitor 2-DG has a notable synergistic antiproliferative effect by further reducing ATP production and inducing intrinsic apoptosis, thus further highlighting the potential therapeutic value of targeted PRMT3 degradation. These data clearly demonstrated that degrader 11 is a powerful chemical tool for investigating PRMT3 protein functions.

Protein Arginine Methyltransferases in Pancreatic Ductal Adenocarcinoma: New Molecular Targets for Therapy

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignant disease with a low 5-year overall survival rate. It is the third-leading cause of cancer-related deaths in the United States. The lack of robust therapeutics, absence of effective biomarkers for early detection, and aggressive nature of the tumor contribute to the high mortality rate of PDAC. Notably, the outcomes of recent immunotherapy and targeted therapy against PDAC remain unsatisfactory, indicating the need for novel therapeutic strategies. One of the newly described molecular features of PDAC is the altered expression of protein arginine methyltransferases (PRMTs). PRMTs are a group of enzymes known to methylate arginine residues in both histone and non-histone proteins, thereby mediating cellular homeostasis in biological systems. Some of the PRMT enzymes are known to be overexpressed in PDAC that promotes tumor progression and chemo-resistance via regulating gene transcription, cellular metabolic processes, RNA metabolism, and epithelial mesenchymal transition (EMT). Small-molecule inhibitors of PRMTs are currently under clinical trials and can potentially become a new generation of anti-cancer drugs. This review aims to provide an overview of the current understanding of PRMTs in PDAC, focusing on their pathological roles and their potential as new therapeutic targets.

Arginine methylation and respiratory disease

Arginine methylation, a vital post-translational modification, plays a pivotal role in numerous cellular functions such as signal transduction, DNA damage response and repair, regulation of gene transcription, mRNA splicing, and protein interactions. Central to this modification is the role of protein arginine methyltransferases (PRMTs), which have been increasingly recognized for their involvement in the pathogenesis of various respiratory diseases. This review begins with an exploration of the biochemical underpinnings of arginine methylation, shedding light on the intricate molecular regulatory mechanisms governed by PRMTs. It then delves into the impact of arginine methylation and the dysregulation of arginine methyltransferases in diverse pulmonary disorders. Concluding with a focus on the therapeutic potential and recent advancements in PRMT inhibitors, this article aims to offer novel perspectives and therapeutic avenues for the management and treatment of respiratory diseases.

PRMT3-Mediated Arginine Methylation of METTL14 Promotes Malignant Progression and Treatment Resistance in Endometrial Carcinoma

Protein arginine methyltransferase (PRMT) plays essential roles in tumor initiation and progression, but its underlying mechanisms in the treatment sensitivity of endometrial cancer (EC) remain unclear and warrant further investigation. Here, a comprehensive analysis of the Cancer Genome Atlas database and Clinical Proteomic Tumor Analysis Consortium database identifies that PRMT3 plays an important role in EC. Specifically, further experiments show that PRMT3 inhibition enhances the susceptibility of EC cells to ferroptosis. Mechanistically, PRMT3 interacts with Methyltransferase 14 (METTL14) and is involved in its arginine methylation. In addition, PRMT3 inhibition-mediated METTL14 overexpression promotes methylation modification via an m6 A-YTHDF2-dependent mechanism, reducing Glutathione peroxidase 4 (GPX4) mRNA stability, increasing lipid peroxidation levels, and accelerating ferroptosis. Notably, combined PRMT3 blockade and anti-PD-1 therapy display more potent antitumor effects by accelerating ferroptosis in cell-derived xenograft models. The specific PRMT3 inhibitor SGC707 exerts the same immunotherapeutic sensitizing effect in a patient-derived xenograft model. Notably, blocking PRMT3 improves tumor suppression in response to cisplatin and radiation therapy. Altogether, this work demonstrates that PRMT3 depletion is a promising target for EC.

Post-translational modifications and their implications in cancer

Post-translational modifications (PTMs) are crucial regulatory mechanisms that alter the properties of a protein by covalently attaching a modified chemical group to some of its amino acid residues. PTMs modulate essential physiological processes such as signal transduction, metabolism, protein localization, and turnover and have clinical relevance in cancer and age-related pathologies. Majority of proteins undergo post-translational modifications, irrespective of their occurrence in or after protein biosynthesis. Post-translational modifications link to amino acid termini or side chains, causing the protein backbone to get cleaved, spliced, or cyclized, to name a few. These chemical modifications expand the diversity of the proteome and regulate protein activity, structure, locations, functions, and protein-protein interactions (PPIs). This ability to modify the physical and chemical properties and functions of proteins render PTMs vital. To date, over 200 different protein modifications have been reported, owing to advanced detection technologies. Some of these modifications include phosphorylation, glycosylation, methylation, acetylation, and ubiquitination. Here, we discuss about the existing as well as some novel post-translational protein modifications, with their implications in aberrant states, which will help us better understand the modified sites in different proteins and the effect of PTMs on protein functions in core biological processes and progression in cancer.

PRMT3-mediated arginine methylation of IGF2BP1 promotes oxaliplatin resistance in liver cancer

Although oxaliplatin-based chemotherapy has been effective in the treatment of hepatocellular carcinoma (HCC), primary or acquired resistance to oxaliplatin remains a major challenge in the clinic. Through functional screening using CRISPR/Cas9 activation library, transcriptomic profiling of clinical samples, and functional validation in vitro and in vivo, we identify PRMT3 as a key driver of oxaliplatin resistance. Mechanistically, PRMT3-mediated oxaliplatin-resistance is in part dependent on the methylation of IGF2BP1 at R452, which is critical for the function of IGF2BP1 in stabilizing the mRNA of HEG1, an effector of PRMT3-IGF2BP1 axis. Also, PRMT3 overexpression may serve as a biomarker for oxaliplatin resistance in HCC patients. Collectively, our study defines the PRTM3-IGF2BP1-HEG1 axis as important regulators and therapeutic targets in oxaliplatin-resistance and suggests the potential to use PRMT3 expression level in pretreatment biopsy as a biomarker for oxaliplatin-resistance in HCC patients.

Protein arginine methyltransferase 3: A crucial regulator in metabolic reprogramming and gene expression in cancers

Post-translational modification (PTM) of proteins increases proteome diversity, which is critical for maintaining cellular homeostasis. The importance of protein methylation in the regulation of diverse biological processes has been highlighted in the past decades. Methylation of the arginine residue on proteins is catalyzed by members of the protein arginine methyltransferase (PRMT) family. PRMTs play indispensable roles in various pathways that regulate cancer development, progression, and drug response. In this review, we discuss the role of PRMT3, a member of the PRMT family, in controlling oncogenic processes. Additionally, the effects of PRMT3 on the methylation of regulatory proteins involved in transcription, post-transcriptional control, ribosomal maturation, translation, biological synthesis, and metabolic signaling are summarized. Moreover, recent progresses in the development of PRMT3 inhibitors are introduced. Overall, this review highlights the importance of PRMT3 in tumorigenesis and discusses the underlying mechanisms by which PRMT3 modulates cellular metabolism and gene expression. These results also provide a molecular basis for therapeutic modalities by targeting PRMT3.

PRMT3 drives glioblastoma progression by enhancing HIF1A and glycolytic metabolism

Glioblastoma (GBM) is the most common and aggressive primary brain tumor, but the mechanisms underlying tumor growth and progression remain unclear. The protein arginine methyltransferases (PRMTs) regulate a variety of biological processes, however, their roles in GBM growth and progression are not fully understood. In this study, our functional analysis of gene expression networks revealed that among the PRMT family expression of PRMT3 was most significantly enriched in both GBM and low-grade gliomas. Higher PRMT3 expression predicted poorer overall survival rate in patients with gliomas. Knockdown of PRMT3 markedly reduced the proliferation and migration of GBM cell lines and patient-derived glioblastoma stem cells (GSC) in cell culture, while its over-expression increased the proliferative capacity of GSC cells by promoting cell cycle progression. Consistently, stable PRMT3 knockdown strongly inhibited tumor growth in xenograft mouse models, along with a significant decrease in cell proliferation as well as an increase in apoptosis. We further found that PRMT3 reprogrammed metabolic pathways to promote GSC growth via increasing glycolysis and its critical transcriptional regulator HIF1α. In addition, pharmacological inhibition of PRMT3 with a PRMT3-specific inhibitor SGC707 impaired the growth of GBM cells. Thus, our study demonstrates that PRMT3 promotes GBM progression by enhancing HIF1A-mediated glycolysis and metabolic rewiring, presenting a point of metabolic vulnerability for therapeutic targeting in malignant gliomas.

The Role of Protein Arginine Methyltransferases in DNA Damage Response

In response to DNA damage, cells have developed a sophisticated signaling pathway, consisting of DNA damage sensors, transducers, and effectors, to ensure efficient and proper repair of damaged DNA. During this process, posttranslational modifications (PTMs) are central events that modulate the recruitment, dissociation, and activation of DNA repair proteins at damage sites. Emerging evidence reveals that protein arginine methylation is one of the common PTMs and plays critical roles in DNA damage response. Protein arginine methyltransferases (PRMTs) either directly methylate DNA repair proteins or deposit methylation marks on histones to regulate their transcription, RNA splicing, protein stability, interaction with partners, enzymatic activities, and localization. In this review, we summarize the substrates and roles of each PRMTs in DNA damage response and discuss the synergistic anticancer effects of PRMTs and DNA damage pathway inhibitors, providing insight into the significance of arginine methylation in the maintenance of genome integrity and cancer therapies.

Protein post-translational modifications in the regulation of cancer hallmarks

Posttranslational modifications (PTMs) of proteins, the major mechanism of protein function regulation, play important roles in regulating a variety of cellular physiological and pathological processes. Although the classical PTMs, such as phosphorylation, acetylation, ubiquitination and methylation, have been well studied, the emergence of many new modifications, such as succinylation, hydroxybutyrylation, and lactylation, introduces a new layer to protein regulation, leaving much more to be explored and wide application prospects. In this review, we will provide a broad overview of the significant roles of PTMs in regulating human cancer hallmarks through selecting a diverse set of examples, and update the current advances in the therapeutic implications of these PTMs in human cancer.

Fascinating Transformation of SAM-Competitive Protein Methyltransferase Inhibitors from Nucleoside Analogues to Non-Nucleoside Analogues

The abnormal expression of protein methyltransferase (PMT) has been linked with many diseases such as diabetes, neurological disorders, and cancer. S-Adenyl-l-methionine (SAM) is a universal methyl donor and gets converted to S-adenyl-l-homocysteine (SAH), an endogenous competitive inhibitor of SAM. Initially developed SAM/SAH mimetic nucleoside analogues were pan methyltransferase inhibitors. The gradual understanding achieved through ligand-receptor interaction paved the way for various rational approaches of drug design leading to potent and selective nucleoside inhibitors. The present perspective is based on the systematic evolution of selective SAM-competitive heterocyclic non-nucleoside inhibitors from nucleoside inhibitors. This fascinating transition has resolved several issues inherent to nucleoside analogues such as poor pharmacokinetics leading to poor in vivo efficacy. The perspective has brought together various concepts and strategies of drug design that contributed to this rational transition. We firmly believe that the strategies described herein will serve as a template for the future development of drugs in general.

Protein arginine methyltransferase 3 promotes glycolysis and hepatocellular carcinoma growth by enhancing arginine methylation of lactate dehydrogenase A

BACKGROUND

Protein arginine methylation has emerged a pivotal role in cancer progression. However, the role of protein arginine methyltransferase 3 (PRMT3) in hepatocellular carcinoma (HCC) remains unknown.

METHODS

The expression pattern of PRMT3 in HCC was analysed using quantitative real-time-polymerase chain reaction (qRT-PCR), Western blotting and immunohistochemistry assays. Loss- and gain-of-function experiments were carried out to determine the oncogenic role of PRMT3 in HCC. Glucose consumption and lactate production assays, seahorse bioscience, mass spectrometry, co-immunoprecipitation, metabonomic analysis and site-specific mutation experiments were used to explore the underlying molecular mechanisms. Furthermore, a xenograft mouse model was established to investigate the effects of PRMT3 and its inhibitor, SGC707, treatment on tumour growth in vivo.

RESULTS

The expression of PRMT3 was significantly upregulated in HCC, with high expression of which correlated with poor prognosis. PRMT3 knockdown led to the decrease in proliferation, glycolysis of HCC cells and tumour growth, whilst its overexpression showed opposite results. The catalytic activity of PRMT3 was important in mediating these biological processes. Mechanistically, our data showed that PRMT3 interacted with and mediated asymmetric dimethylarginine (ADMA) modification of lactate dehydrogenase A (LDHA) at arginine 112 (R112). Compared with LDHA-wild-type (LDHA-WT) cells, LDHA-R112K-mutant-expressing HCC cells exhibited a decrease in lactate dehydrogenase (LDH) activity, HCC cell glycolysis and proliferation. Furthermore, the administration of SGC707, a selective inhibitor of PRMT3, disrupted the PRMT3-mediated LDHA methylation and abolished PRMT3-induced HCC glycolysis and tumour growth.

CONCLUSIONS

Our results suggested a novel oncogenic role of PRMT3 in HCC, and it could be a promising therapeutic target for HCC by linking post-translational modification and cancer metabolism.

An update on allosteric modulators as a promising strategy targeting histone methyltransferase

Histone methylation is a vital post-translational modification process in epigenetic regulation. The perturbation of histone methylation accounts for many diseases, including malignant cancers. Although achieving significant advances over past decades, orthosteric inhibitors targeting histone methyltransferases still suffer from challenges on subtype selectivity and acquired drug-resistant mutations. As an alternative, new compounds targeting the evolutionarily less conserved allosteric sites, exemplified by HKMTs and PRMTs inhibitors, offer a promising strategy to address this quandary. Herein, we highlight the allosteric sites and mechanisms in histone methyltransferases along with representative allosteric modulators, expecting to facilitate the discovery of allosteric modulators in favor of epigenetic therapy.

Protein arginine methyltransferases and hepatocellular carcinoma: A review

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Protein arginine methylation is essential in multiple biological processes.

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The family of PRMTs is a novel regulator of liver diseases.

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Deregulation of PRMTs is correlated with HCC prognosis and clinical features.

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PRMTs play a vital role in HCC malignancy, immune responses and metabolism.

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PRMTs may represent druggable targets as novel strategies for HCC therapy.

Hepatocellular carcinoma (HCC) is one of the most frequently diagnosed cancers with a high mortality rate worldwide. The complexity of HCC initiation and progression poses a great challenge to the diagnosis and treatment. An increasing number of studies have focused on the emerging roles of protein arginine methylation in cancers, including tumor growth, invasion, metastasis, metabolism, immune responses, chemotherapy sensitivity, etc. The family of protein arginine methyltransferases (PRMTs) is the most important proteins that mediate arginine methylation. The deregulation of PRMTs’ expression and functions in cancers have been gradually unveiled, and many PRMTs inhibitors are in preclinical and clinical investigations now. This review focuses predominantly on the aberrant expression of PRMTs, underlying mechanisms, as well as their potential applications in HCC, and provide novel insights into HCC therapy.

Acetylation, Methylation and Allysine Modification Profile of Viral and Host Proteins during Influenza A Virus Infection

Protein modifications dynamically occur and regulate biological processes in all organisms. Towards understanding the significance of protein modifications in influenza virus infection, we performed a global mass spectrometry screen followed by bioinformatics analyses of acetylation, methylation and allysine modification in human lung epithelial cells in response to influenza A virus infection. We discovered 8 out of 10 major viral proteins and 245 out of 2280 host proteins detected to be differentially modified by three modifications in infected cells. Some of the identified proteins were modified on multiple amino acids residues and by more than one modification; the latter occurred either on different or same residues. Most of the modified residues in viral proteins were conserved across >40 subtypes of influenza A virus, and influenza B or C viruses and located on the protein surface. Importantly, many of those residues have already been determined to be critical for the influenza A virus. Similarly, many modified residues in host proteins were conserved across influenza A virus hosts like humans, birds, and pigs. Finally, host proteins undergoing the three modifications clustered in common functional networks of metabolic, cytoskeletal, and RNA processes, all of which are known to be exploited by the influenza A virus.

Protein arginine methyltransferases: promising targets for cancer therapy

Protein methylation, a post-translational modification (PTM), is observed in a wide variety of cell types from prokaryotes to eukaryotes. With recent and rapid advancements in epigenetic research, the importance of protein methylation has been highlighted. The methylation of histone proteins that contributes to the epigenetic histone code is not only dynamic but is also finely controlled by histone methyltransferases and demethylases, which are essential for the transcriptional regulation of genes. In addition, many nonhistone proteins are methylated, and these modifications govern a variety of cellular functions, including RNA processing, translation, signal transduction, DNA damage response, and the cell cycle. Recently, the importance of protein arginine methylation, especially in cell cycle regulation and DNA repair processes, has been noted. Since the dysregulation of protein arginine methylation is closely associated with cancer development, protein arginine methyltransferases (PRMTs) have garnered significant interest as novel targets for anticancer drug development. Indeed, several PRMT inhibitors are in phase 1/2 clinical trials. In this review, we discuss the biological functions of PRMTs in cancer and the current development status of PRMT inhibitors in cancer therapy.

Toward Understanding Molecular Recognition between PRMTs and their Substrates

Protein arginine methylation is a widespread eukaryotic posttranslational modification that occurs with as much frequency as ubiquitinylation. Yet, how the nine different human protein arginine methyltransferases (PRMTs) recognize their respective protein targets is not well understood. This review summarizes the progress that has been made over the last decade or more to resolve this significant biochemical question. A multipronged approach involving structural biology, substrate profiling, bioorthogonal chemistry and proteomics is discussed.

Arginine Methylation in Brain Tumors: Tumor Biology and Therapeutic Strategies

Protein arginine methylation is a common post-translational modification that plays a pivotal role in cellular regulation. Protein arginine methyltransferases (PRMTs) catalyze the modification of target proteins by adding methyl groups to the guanidino nitrogen atoms of arginine residues. Protein arginine methylation takes part in epigenetic and cellular regulation and has been linked to neurodegenerative diseases, metabolic diseases, and tumor progression. Aberrant expression of PRMTs is associated with the development of brain tumors such as glioblastoma and medulloblastoma. Identifying PRMTs as plausible contributors to tumorigenesis has led to preclinical and clinical investigations of PRMT inhibitors for glioblastoma and medulloblastoma therapy. In this review, we discuss the role of arginine methylation in cancer biology and provide an update on the use of small molecule inhibitors of PRMTs to treat glioblastoma, medulloblastoma, and other cancers.

The role of protein arginine methyltransferases in kidney diseases

The methylation of arginine residues by protein arginine methyltransferases (PRMTs) is a crucial post-translational modification for many biological processes, including DNA repair, RNA processing, and transduction of intra- and extracellular signaling. Previous studies have reported that PRMTs are extensively involved in various pathologic states, including cancer, inflammation, and oxidative stress reaction. However, the role of PRMTs has not been well described in kidney diseases. Recent studies have shown that aberrant function of PRMTs and its metabolic products-symmetric dimethylarginine (SDMA) and asymmetric dimethylarginine (ADMA)-are involved in several renal pathological processes, including renal fibrosis, acute kidney injury (AKI), diabetic nephropathy (DN), hypertension, graft rejection and renal tumors. We aim in this review to elucidate the possible roles of PRMTs in normal renal function and various kidney diseases.

The role of histone methylation in the development of digestive cancers: a potential direction for cancer management

Digestive cancers are the leading cause of cancer-related death worldwide and have high risks of morbidity and mortality. Histone methylation, which is mediated mainly by lysine methyltransferases, lysine demethylases, and protein arginine methyltransferases, has emerged as an essential mechanism regulating pathological processes in digestive cancers. Under certain conditions, aberrant expression of these modifiers leads to abnormal histone methylation or demethylation in the corresponding cancer-related genes, which contributes to different processes and phenotypes, such as carcinogenesis, proliferation, metabolic reprogramming, epithelial–mesenchymal transition, invasion, and migration, during digestive cancer development. In this review, we focus on the association between histone methylation regulation and the development of digestive cancers, including gastric cancer, liver cancer, pancreatic cancer, and colorectal cancer, as well as on its clinical application prospects, aiming to provide a new perspective on the management of digestive cancers.

Glyceraldehyde-3-phosphate Dehydrogenase is a Multifaceted Therapeutic Target

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a glycolytic enzyme whose role in cell metabolism and homeostasis is well defined, while its function in pathologic processes needs further elucidation. Depending on the cell context, GAPDH may bind a number of physiologically important proteins, control their function and correspondingly affect the cell’s fate. These interprotein interactions and post-translational modifications of GAPDH mediate its cytotoxic or cytoprotective functions in the manner of a Janus-like molecule. In this review, we discuss the functional features of the enzyme in cellular physiology and its possible involvement in human pathologies. In the last part of the article, we describe drugs that can be employed to modulate this enzyme’s function in some pathologic states.