Downregulation of PRMT1 promotes the senescence and migration of a non-MYCN amplified neuroblastoma SK-N-SH cells

PRMT1 mediates the proliferation of Y79 retinoblastoma cells by regulating the p53/p21/CDC2/cyclin B pathway

Retinoblastoma (RB) is the most common intraocular malignancy among children and presents a certain mortality risk, especially in low- and middle-income countries. Clarifying the molecular mechanisms underlying the onset and progression of retinoblastoma is vital for devising effective cancer treatment approaches. PRMT1, a major type I PRMT, plays significant roles in cancer development. However, its expression and role in retinoblastoma are still unclear. Our research revealed a marked increase in PRMT1 levels in both retinoblastoma tissues and Y79 cells. The overexpression of PRMT1 in Y79 cells promoted their growth and cell cycle progression. Conversely, the suppression of PRMT1 hindered the growth of Y79 cells and impeded cell cycle progression. Mechanistically, PRMT1 mediated the growth of Y79 retinoblastoma cells by targeting the p53/p21/CDC2/Cyclin B pathway. Additionally, the ability of PRMT1 knockdown to suppress cell proliferation was also observed in vivo. Overall, PRMT1 could function as a potential target for therapeutic treatment in individuals with retinoblastoma.

The protein arginine methyltransferase family (PRMTs) regulates metastases in various tumors: From experimental study to clinical application

Tumor metastasis is the leading cause of mortality among advanced cancer patients. Understanding its mechanisms and treatment strategies is vital for clinical application. Arginine methylation, a post-translational modification catalyzed by protein arginine methyltransferases (PRMTs), is implicated in diverse physiological processes and disease progressions. Previous research has demonstrated PRMTs' involvement in tumor occurrence, progression, and metastasis. This review offers a comprehensive summary of the relationship between PRMTs, prognosis, and metastasis in various cancers. Our focus centers on elucidating the molecular mechanisms through which PRMTs regulate tumor metastasis. We also discuss relevant clinical trials and effective PRMT inhibitors, including chemical compounds, long non-coding RNA (lncRNA), micro-RNA (miRNA), and nanomaterials, for treating tumor metastasis. While a few studies present conflicting results, the overall trajectory suggests that inhibiting arginine methylation exhibits promise in curtailing tumor metastasis across various cancers. Nonetheless, the underlying mechanisms and molecular interactions are diverse. The development of inhibitors targeting arginine methylation, along with the progression of clinical trials, holds substantial potential in the field of tumor metastasis, meriting sustained attention.

PRMT1 methylation of WTAP promotes multiple myeloma tumorigenesis by activating oxidative phosphorylation via m6A modification of NDUFS6

Epigenetic modifications play important roles during the pathogenesis of multiple myeloma (MM). Herein, we found that protein arginine methyltransferase 1 (PRMT1) was highly expressed in MM patients, which was positively correlated with MM stages. High PRMT1 expression was correlated with adverse prognosis in MM patients. We further showed that silencing PRMT1 inhibited MM proliferation and tumorigenesis in vitro and in vivo. Mechanistically, we revealed that the knockdown of PRMT1 reduced the oxidative phosphorylation (OXPHOS) of MM cells through NDUFS6 downregulation. Meanwhile, we identified that WTAP, a key component of the m6A methyltransferase complex, was methylated by PRMT1, and NDUFS6 was identified as a bona fide m6A target of WTAP. Finally, we found that the combination of PRMT1 inhibitor and bortezomib synergistically inhibited MM progression. Collectively, our results demonstrate that PRMT1 plays a crucial role during MM tumorigenesis and suggeste that PRMT1 could be a potential therapeutic target in MM.

Senescent Tumor Cells Are Frequently Present at the Invasion Front: Implications for Improving Disease Control in Patients with Locally Advanced Prostate Cancer

INTRODUCTION

Local tumor invasion is a critical factor for the outcome of men with prostate cancer. In particular, seminal vesicle invasion (SVI) has been reported to be associated with a more unfavorable prognosis. A better understanding of the functional state of invading prostate cancer cells is crucial to develop novel therapeutic strategies for patients with locally advanced disease.

METHODS

The prognostic impact of local tumor progression was ascertained in over 1,000 men with prostate cancer. Prostate cancer specimens were stained by double-immunohistochemistry for the proliferation marker Ki-67 and the senescence marker p16INK4A. The migratory properties of senescent prostate cancer cells were analyzed in vitro using a wound healing assay and immunofluorescence microscopy for p16INK4A.

RESULTS

We confirm the notion that patients with SVI have a more unfavorable prognosis than patients with extraprostatic extension alone. Surprisingly, we found that the tumor invasion front frequently harbors p16INK4A-positive and Ki-67-negative, i.e., senescent, tumor cells. While the intraprostatic tumor periphery was a hotspot for both proliferation and expression of p16INK4A, the area of SVI showed less proliferative activity but was at the same time a hotspot of cells with increased nuclear p16INK4A expression. Senescence was associated with an accelerated migration of prostate cancer cells in vitro.

CONCLUSION

This proof-of-concept study shows that invading prostate cancer cells frequently show signs of cellular senescence. This finding may open new avenues for neoadjuvant and adjuvant treatment concepts in men with locally advanced prostate cancer.

Dual isothermal amplification all-in-one approach for rapid and highly sensitive quantification of plasma circulating MYCN gene of neuroblastoma

A dual isothermal amplification assay with dual fluorescence signal detection strategy, named dual isothermal amplification all-in-one approach, was developed for rapid, one-step, highly sensitive quantification of plasma circulating MYCN copy number of neuroblastoma (NB). The developed strategy consisted of rolling circle amplification (RCA) and loop-mediated isothermal amplification (LAMP) on a real-time PCR system using highly specific probe, molecular beacon (MB), as detection probe. The developed strategy possessing a broad linear dynamic range of 10 aM to 1 pM for both target gene (MYCN) and reference gene (NAGK). The ratio of the MYCN copy number to NAGK copy number (M/N ratio) was detected by the developed approach in cell lines, NB tumor tissues, hepatoblastoma tumor tissues and Wilms' tumor tissues, to which the M/N ratios were consistent with previous reports. In particular, the M/N ratio in NB clinical tissue specimens and NB plasma specimens detected with the developed approach were in keeping with the standard RT-PCR approach. More importantly, the M/N ratio in NB tissue samples and corresponding plasma samples of NB patients were consistent with each other with a correlation coefficient of 0.9690, indicating that plasma circulating MYCN is a promising indicator for the risk classification of NB.

Design and Synthesis of Novel PRMT1 Inhibitors and Investigation of Their Effects on the Migration of Cancer Cell

Protein arginine methyltransferase 1 (PRMT1) can catalyze the protein arginine methylation by transferring the methyl group from S-adenosyl-L-methionine (SAM) to the guanidyl nitrogen atom of protein arginine, which influences a variety of biological processes including epithelial-mesenchymal transition (EMT) and EMT-mediated mobility of cancer cells. The upregulation of PRMT1 is involved in a diverse range of cancer, such as lung cancer, and there is an urgent need to develop novel and potent PRMT1 inhibitors. In this article, a series of 2,5-substituted furan derivatives and 2,4-substituted thiazole derivatives were designed and synthesized by targeting at the substrate arginine-binding site on PRMT1, and 10 compounds demonstrated significant inhibitory effects against PRMT1. Among them, the most potent inhibitor, compound 1r (WCJ-394), significantly affected the expression of PRMT1-related proteins in A549 cells and downregulated the expression of mesenchymal markers, by which WCJ-394 inhibited the TGF-β1-induced EMT in A549 cells and prevented the cancer cell migration. The current study demonstrated that WCJ-394 was a potent PRMT1 inhibitor, which could be used as the leading compound for further drug discovery.

A More Biomimetic Cell Migration Assay with High Reliability and Its Applications

Cell migration refers to the directional movement of cells to the surrounding cell-free zone in response to chemical and mechanical stimuli. A cell migration assay is an essential device for studying pharmaceutical and medical problems. In this paper, we present a novel approach to a cell migration assay on a chip with two merits, namely (i) simultaneous creation of many cell samples on the same condition and (ii) cells migrating while being stressed in a fluidic environment. The first merit has addressed the problem of poor reproducibility in experimental studies for medical problems such as wound healing, and the second merit has made the cell migration device, which is an in vitro environment, more biomimetic. The two merits are attributed to a novel mechanical method to simultaneously create many cell-free zones and to the design of a microfluidic process to create shear stress in cells uniformly. Two applications were studied on our device to explore its effectiveness. The first application is regarding the combination chemotherapy of cisplatin and doxorubicin (Adriamycin) on cervical cancer cells (HeLa). The second application is regarding inhibiting the migration of endothelial cells (HUVEC) in the process of anti-angiogenesis.

Naturally occurring cancer-associated mutations disrupt oligomerization and activity of protein arginine methyltransferase 1 (PRMT1)

Protein arginine methylation is a posttranslational modification catalyzed by the protein arginine methyltransferase (PRMT) enzyme family. Dysregulated protein arginine methylation is linked to cancer and a variety of other human diseases. PRMT1 is the predominant PRMT isoform in mammalian cells and acts in pathways regulating transcription, DNA repair, apoptosis, and cell proliferation. PRMT1 dimer formation, which is required for methyltransferase activity, is mediated by interactions between a structure called the dimerization arm on one monomer and a surface of the Rossman Fold of the other monomer. Given the link between PRMT1 dysregulation and disease and the link between PRMT1 dimerization and activity, we searched the Catalogue of Somatic Mutations in Cancer (COSMIC) database to identify potential inactivating mutations occurring in the PRMT1 dimerization arm. We identified three mutations that correspond to W215L, Y220N, and M224V substitutions in human PRMT1V2 (isoform 1) (W197L, Y202N, M206V in rat PRMT1V1). Using a combination of site-directed mutagenesis, analytical ultracentrifugation, native PAGE, and activity assays, we found that these conservative substitutions surprisingly disrupt oligomer formation and substantially impair both S-adenosyl-L-methionine (AdoMet) binding and methyltransferase activity. Molecular dynamics simulations suggest that these substitutions introduce novel interactions within the dimerization arm that lock it in a conformation not conducive to dimer formation. These findings provide a clear, if putative, rationale for the contribution of these mutations to impaired arginine methylation in cells and corresponding health consequences.

Arginine Methyltransferase PRMT1 Regulates p53 Activity in Breast Cancer

The protein p53 is one of the most important tumor suppressors, responding to a variety of stress signals. Mutations in p53 occur in about half of human cancer cases, and dysregulation of the p53 function by epigenetic modifiers and modifications is prevalent in a large proportion of the remainder. PRMT1 is the main enzyme responsible for the generation of asymmetric-dimethylarginine, whose upregulation or aberrant splicing has been observed in many types of malignancies. Here, we demonstrate that p53 function is regulated by PRMT1 in breast cancer cells. PRMT1 knockdown activated the p53 signal pathway and induced cell growth-arrest and senescence. PRMT1 could directly bind to p53 and inhibit the transcriptional activity of p53 in an enzymatically dependent manner, resulting in a decrease in the expression levels of several key downstream targets of the p53 pathway. We were able to detect p53 asymmetric-dimethylarginine signals in breast cancer cells and breast cancer tissues from patients, and the signals could be significantly weakened by silencing of PRMT1 with shRNA, or inhibiting PRMT1 activity with a specific inhibitor. Furthermore, PRMT1 inhibitors significantly impeded cell growth and promoted cellular senescence in breast cancer cells and primary tumor cells. These results indicate an important role of PRMT1 in the regulation of p53 function in breast tumorigenesis.

Global analysis of protein arginine methylation

Quantitative information about the levels and dynamics of post-translational modifications (PTMs) is critical for an understanding of cellular functions. Protein arginine methylation (ArgMet) is an important subclass of PTMs and is involved in a plethora of (patho)physiological processes. However, because of the lack of methods for global analysis of ArgMet, the link between ArgMet levels, dynamics, and (patho)physiology remains largely unknown. We utilized the high sensitivity and robustness of nuclear magnetic resonance (NMR) spectroscopy to develop a general method for the quantification of global protein ArgMet. Our NMR-based approach enables the detection of protein ArgMet in purified proteins, cells, organoids, and mouse tissues. We demonstrate that the process of ArgMet is a highly prevalent PTM and can be modulated by small-molecule inhibitors and metabolites and changes in cancer and during aging. Thus, our approach enables us to address a wide range of biological questions related to ArgMet in health and disease.

PRMT1 is a novel molecular therapeutic target for clear cell renal cell carcinoma

Background and Objective: Epigenetic alterations are common events in clear cell renal cell carcinoma (ccRCC), and protein arginine methyltransferase 1 (PRMT1) is an important epigenetic regulator in cancers. However, its role in ccRCC remains unclear.

Methods: We investigated PRMT1 expression level and its correlations to clinicopathological factors and prognosis in ccRCC patients based on ccRCC tissue microarrays (TMAs). Genetic knockdown and pharmacological inhibition using a novel PRMT1 inhibitor DCPT1061 were performed to investigate the functional role of PRMT1 in ccRCC proliferation. Besides, we confirmed the antitumor effect of PRMT1 inhibitor DCPT1061 in ccRCC cell-derived tumor xenograft (CDX) models as well as patient-derived tumor xenograft (PDX) models.

Results: We found PRMT1 expression was remarkably upregulated in tumor tissues and associated with poor pathologic characters and outcomes of ccRCC patients. Furthermore, genetic knockdown and pharmacological inhibition of PRMT1 by a novel potent inhibitor DCPT1061 dramatically induced G1 cell cycle arrest and suppressed ccRCC cell growth. Mechanistically, RNA sequencing and further validation identified Lipocalin2 (LCN2), a secreted glycoprotein implicated in tumorigenesis, as a crucial regulator of ccRCC growth and functional downstream effector of PRMT1. Epigenetic silencing of LCN2 autocrine secretion by PRMT1 deficiency decreased downstream p-AKT, leading to reduced p-RB and cell growth arrest through the neutrophil gelatinase associated lipocalin receptor (NGALR). Moreover, PRMT1 inhibition by DCPT1061 not only inhibited tumor growth but also sensitized ccRCC to sunitinib treatment in vivo by attenuating sunitinib-induced upregulation of LCN2-AKT-RB signaling.

Conclusion: Taken together, our study revealed a PRMT1-dependent epigenetic mechanism in the control of ccRCC tumor growth and drug resistance, indicating PRMT1 may serve as a promising target for therapeutic intervention in ccRCC patients.

Cellular senescence and tumor promotion: Role of the Unfolded Protein Response

Senescence is a cellular state which can be viewed as a stress response phenotype implicated in various physiological and pathological processes, including cancer. Therefore, it is of fundamental importance to understand why and how a cell acquires and maintains a senescent phenotype. Direct evidence has pointed to the homeostasis of the endoplasmic reticulum whose control appears strikingly affected during senescence. The endoplasmic reticulum is one of the sensing organelles that transduce signals between different pathways in order to adapt a functional proteome upon intrinsic or extrinsic challenges. One of these signaling pathways is the Unfolded Protein Response (UPR), which has been shown to be activated during senescence. Its exact contribution to senescence onset, maintenance, and escape, however, is still poorly understood. In this article, we review the mechanisms through which the UPR contributes to the appearance and maintenance of characteristic senescent features. We also discuss whether the perturbation of the endoplasmic reticulum proteostasis or accumulation of misfolded proteins could be possible causes of senescence, and-as a consequence-to what extent the UPR components could be considered as therapeutic targets allowing for the elimination of senescent cells or altering their secretome to prevent neoplastic transformation.

Pharmacologic downregulation of protein arginine methyltransferase1 expression by adenosine dialdehyde increases cell senescence in breast cancer

We investigated the role of protein arginine methylation (PAM) in estrogen receptor (ER)-positive breast cancer cells through pharmacological intervention. Tamoxifen (TAM) or adenosine dialdehyde (ADOX), independently, triggered cell cycle arrest and down-regulated PAM, as reduced protein arginine methyltransferase1 (PRMT1) mRNA and asymmetric dimethylarginine (ADMA) levels. Synergistic effect of these compounds elicited potent anti-cancer effect. However, reduction in ADMA was not proportionate with the compound-induced down-regulation of PRMT1 mRNA. We hypothesized that the disproportionate effect is due to the influence of the compounds on other methyltransferases, which catalyze the arginine dimethylation reaction and the diversity in the degree of drug-protein interaction among these methyltransferases. In silico analyses revealed that independently, ADOX or TAM, binds with phosphatidylethanolamine-methyltransferase (PEMT) or betaine homocysteine-methyl transferase (BHMT); and that the binding affinity of ADOX with PEMT or BHMT is prominent than TAM. These observations suggest that in breast cancer, synergistic effect of ADOX + TAM elicits impressive protective function by regulating PAM; and plausibly, restoration of normal enzyme activities of methyltransferases catalyzing arginine dimethylation could have clinical benefits.

Prognostic significance of MYCN related genes in pediatric neuroblastoma: a study based on TARGET and GEO datasets

Background

Neuroblastoma patients with MYCN amplification are associated with poor prognosis. However, the prognostic relevance of MYCN associated genes in neuroblastoma is unclear.

Methods

The expression profiles of MYCN associated genes were identified from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) and Gene Expression Omnibus (GEO) datasets. Enriched transcription factors and signaling pathways were determined using gene set enrichment analysis (GSEA). Kaplan-Meier plotter was used to identify the prognostic relevance of MYCN associated genes. Multivariate cox regression and Spearman’s correlation were used to determine the correlation coefficients of MYCN associated genes.

Results

In TARGET and GSE85047 datasets, neuroblastoma patients with MYCN amplification were associated with worse prognosis. Transcription factor MYC was positively associated with MYCN amplification in GSEA assay. We identified 13 MYC target genes which were increased in neuroblastoma patients with MYCN amplification in TARGET, GSE19274 and GSE85047 datasets. Moreover, six out of the 13 MYC target genes ARMC6, DCTPP1, EIF4G1, ELOVL6, FBL and PRMT1 were associated with adverse prognosis in TARGET and GSE85047 datasets. Transcription factor E2F1 was up-regulated by MYCN amplification and associated with the poor prognosis of neuroblastoma. Furthermore, RPS19 in ribosome signaling pathway was also associated with MYCN amplification and correlated with the poor prognosis of neuroblastoma. At last, we showed that most of MYCN target genes were correlated with each other. However, EIF4G1 was an independent prognostic marker. And the prognostic effects of the combination of MYCN amplification and EIF4G1 expression were more significant than MYCN or EIF4G1 alone.

Conclusions

MYCN target genes ARMC6, DCTPP1, EIF4G1, ELOVL6, FBL, PRMT1, E2F1 and RPS19 had significant prognostic effects in pediatric neuroblastoma. And neuroblastoma patients without MYCN amplification and low EIF4G1 expression had best prognosis.

PRMT1 promotes neuroblastoma cell survival through ATF5

Aberrant expression of protein arginine methyltransferases (PRMTs) has been implicated in a number of cancers, making PRMTs potential therapeutic targets. But it remains not well understood how PRMTs impact specific oncogenic pathways. We previously identified PRMTs as important regulators of cell growth in neuroblastoma, a deadly childhood tumor of the sympathetic nervous system. Here, we demonstrate a critical role for PRMT1 in neuroblastoma cell survival. PRMT1 depletion decreased the ability of murine neuroblastoma sphere cells to grow and form spheres, and suppressed proliferation and induced apoptosis of human neuroblastoma cells. Mechanistic studies reveal the prosurvival factor, activating transcription factor 5 (ATF5) as a downstream effector of PRMT1-mediated survival signaling. Furthermore, a diamidine class of PRMT1 inhibitors exhibited anti-neuroblastoma efficacy both in vitro and in vivo. Importantly, overexpression of ATF5 rescued cell apoptosis triggered by PRMT1 inhibition genetically or pharmacologically. Taken together, our findings shed new insights into PRMT1 signaling pathway, and provide evidence for PRMT1 as an actionable therapeutic target in neuroblastoma.

Alternative 3' splice site selection of intron 5 within the prmt8 gene results in a novel variant widely distributed in vertebrates and specifically abundant in Aves

PRMT8 is a neuron-specific protein arginine methyltransferase in vertebrates. From data mining, we found a novel prmt8e6+43 splicing variant with a 43-nucleotide (nt) extension at the 5' of exon 6 in chicken. RT-PCR analyses confirmed the existence of two splicing variants but also detected a third upper signal. The triplet pattern detected in chicken suggests that one strand from the prmt8e6+43 transcript and one strand from the regular splicing products form a heteroduplex with a bulb conformation and the two transcripts are of similar abundance. One short plus one faint upper heteroduplex signal detected in mouse and human indicate that the level of the variant is much less than the normal one in mammals. The relative expression of the normal and prmt8e6+43 variants in different species can be inferred from the reads of intron 5 that contains the 43-nt extension or not in the RNA-seq data of NCBI Gene database. The results of the analyses showed that the prmt8e6+43 variant is relatively abundant in birds but much less or even not detected in mammalian species. As conserved intron 5 sequences and evidences of alternative splicing (AS) are detected in elephant shark, a cartilaginous fish with the slowest-evolving genome, we propose that the prmt8e6+43 variant is present in the common ancestor of jawed vertebrates. The prmt8e6+43 variant includes a premature termination codon and thus should encode a truncated PRMT8 with deletion from the dimerization arm. Western blot analyses showed very weak low-molecular-weight signals in chicken, which might be the C-terminal truncated PRMT8. Why avian species maintain high RNA but not protein levels of the prmt8e6+43 variant and whether the evolutionary conserved sequence and AS might regulate PRMT8 expression require further investigation.