WTAP facilitates progression of hepatocellular carcinoma via m6A-HuR-dependent epigenetic silencing of ETS1

Molecular mechanism of Wilms tumour 1-associated protein in diabetes-related dry eye disease by mediating m6A methylation modification of lncRNA NEAT1

Background: Dry eye disease (DED) is often secondary to diabetes mellitus (DM).Purpose: This study is to explore the action of Wilms tumor 1-associated protein (WTAP) in DM-DED via lncRNA NEAT1 m6A methylation.Methods: DM-DED mouse models were treated with sh-WTAP/sh-NEAT1, followed by assessment of corneal epithelial damage/histopathological changes. HCE-2 cells were exposed to hyperosmotic conditions to establish in vitro DED models and treated with oe-NEAT1/sh-NEAT1/sh-WTAP/nigericin (an NLRP3 inflammasome inducer). Cell viability/apoptosis were evaluated by CCK-8/TUNEL. Levels of WTAP/NEAT1/inflammatory factors/NLRP3 inflammasome- and apoptosis-related markers were determined. m6A modification was examined by MeRIP-qPCR and NEAT1 stability was also detected.Results: DM-DED mice exhibited up-regulated WTAP/NEAT1 expression and severe corneal damage, whereas WTAP/NEAT1 knockdown alleviated inflammation/corneal damage. In hyperosmolarity-induced HCE-2 cells, NEAT1 aggravated inflammation and apoptosis, while NEAT1 knockdown suppressed NLRP3 inflammasome activation and ameliorated cell injury. Hyperosmolarity-induced WTAP expression increased m6A modification and NEAT1 mRNA stability. WTAP mediated m6A methylation of NEAT1 and NLRP3 inflammasome activation in DM-DED mice.

Transcription factor ETS1‑mediated ECT2 expression promotes the malignant behavior of prostate cancer cells

Prostate cancer remains the most prevalent malignancy diagnosed in men worldwide. Epithelial cell transforming sequence 2 (ECT2) is an oncogene involved in the progression of human tumors. The present study aimed to explore the involvement of ECT2 in prostate cancer and its participation in the malignant progression of prostate cancer. ECT2 expression in prostate cancer cell lines was examined via reverse transcription-quantitative PCR and western blotting. The effects of knockdown of ECT2 expression in PC-3 cells on cellular biological behaviors, including proliferation, migration and invasion, were examined using Cell Counting Kit-8, colony formation, wound healing and Transwell assays. The glycolysis level was determined based on the lactate release, glucose uptake, oxygen consumption rate and extracellular acidification rate. The binding relationship between ECT2 and ETS1 was verified using luciferase reporter and chromatin immunoprecipitation assays. The results indicated that ECT2 was highly expressed in prostate cancer cell lines. Knockdown of ECT2 expression could inhibit cell proliferation, migration, invasion and glycolysis. In addition, the transcription factor ETS1 could directly bind to the ECT2 promoter and positively regulate ECT2 expression. These data were combined with the results of rescue experiments and demonstrated that the inhibitory effects of the knockdown of ECT2 expression on the malignant behavior and glycolysis of prostate cancer cells were partially reversed by ETS1 overexpression. In conclusion, ETS1 induced transcriptional upregulation of ECT2 and enhanced the malignant biological behaviors of prostate cancer cells, thereby promoting the progression of prostate cancer. This evidence provides a theoretical basis for the treatment of prostate cancer.

N6-methyladenosine dynamics in placental development and trophoblast functions, and its potential role in placental diseases

N6-methyladenosine (m6A) is the most abundant modification controlling RNA metabolism and cellular functions, but its roles in placental development are still poorly understood. Here, we characterized the synchronization of m6A modifications and placental functions by mapping the m6A methylome in human placentas (n = 3, each trimester), revealing that the dynamic patterns of m6A were associated with gene expression homeostasis and different biological pathways in placental development. Then, we generated trophoblast-specific knockout mice of Wtap, a critical component of methyltransferase complex, and demonstrated that Wtap was essential for trophoblast proliferation, placentation and perinatal growth. Further in vitro experiments which includes cell viability assays and series molecular binding assays demonstrated that WTAP-m6A-IGF2BP3 axis regulated the RNA stability and translation of Anillin (ANLN) and VEGFA, promoting trophoblast proliferation and secretion. Dysregulation of this regulatory axis was observed in placentas from pregnancies with fetal growth restriction (FGR) or preeclampsia, revealing the pathogenic effects of imbalanced m6A modifications. Therefore, our findings provide novel insights into the functions and regulatory mechanisms of m6A modifications in placental development and placental-related gestational diseases.

Inhibition of KIAA1429/HK1 axis enhances the sensitivity of liver cancer cells to sorafenib by regulating the Warburg effect

N6-methyladenosine (m6A) serves as the most abundant posttranscription modification. However, the role of m6A in tumorigenesis and chemotherapeutic drugs sensitivity remains largely unclear. Present research focuses on the potential function of the m6A writer KIAA1429 in tumor development and sorafenib sensitivity in liver cancer. We found that the level of KIAA1429 was significantly elevated in liver cancer tissues and cells and was closely associated with poorer prognosis. Functionally, KIAA1429 promoted the proliferation and Warburg effect of liver cancer cells in vitro and in vivo. RNA-seq and MeRIP-seq analysis revealed the glycolysis was one of the most affected pathways by KIAA1429, and m6A-modified HK1 was the most likely targeted gene to regulate the Warburg effect. KIAA1429 depletion decreased Warburg effect and increased sorafenib sensitivity in liver cancer. Mechanistically, KIAA1429 could affect the m6A level of HK1 mRNA through directly binding with it. Moreover, KIAA1429 cooperated with the m6A reader HuR to enhance HK1 mRNA stability, thereby upregulating its expression. These findings demonstrated that KIAA1429/HK1 axis decreases the sensitivity of liver cancer cells to sorafenib by regulating the Warburg effect, which may provide a novel therapeutic target for liver cancer treatment.

Apoptosis Signal-Regulated Kinase-1 Promotes Nucleus Pulposus Cell Senescence and Apoptosis to Regulate Intervertebral Disc Degeneration

This study investigated the role of apoptosis signal-regulated kinase-1 (ASK1) in intervertebral disc degeneration (IDD). The nucleus pulposus (NP) tissues of non-IDD and IDD patients were subjected to hematoxylin and eosin, Safranin O-fast green, and immunohistochemical staining. Quantitative real-time PCR was used to assess the ASK1 mRNA level within NP tissue samples and cells. The Cell Counting Kit-8 assay, senescence-associated β-galactosidase staining, and flow cytometry were conducted to assess the viability, senescence, and apoptosis of NP cells, respectively. Extracellular matrix-related factors were detected using Western blot analysis. Furthermore, the effect of ASK1 on the IDD rat model was evaluated. Finally, c-Jun N-terminal kinase (JNK) inhibitors were used to verify the effect of the JNK/p38 signaling on IDD. ASK1 mRNA and protein were up-regulated within NP tissue samples from the IDD group, IL-1β-stimulated NP cells, and IDD rats. ASK1 inhibition promoted cell viability and repressed the senescence and apoptosis of NP cells, promoted collagen II and aggrecan, inhibited matrix metalloproteinase 3/9 and a disintegrin and metalloproteinase with thrombospondin motifs 4/5 protein levels, and increased NP cells in rat intervertebral disc tissues. ASK1 overexpression exerted the opposite effects of ASK1 inhibition on NP cells. Additionally, JNK/p38 signaling suppression could reverse the ASK1 up-regulation-induced dysfunction. In conclusion, ASK1 facilitated the senescence and apoptosis of NP cells in promoting IDD progression via the JNK/p38 pathway.

Functions and mechanisms of RNA m6A regulators in breast cancer (Review)

Breast cancer (BC) is a major malignant tumor in females and the incidence rate of BC has increased worldwide in recent years. N6‑methyladenosine (m6A) is a methylation modification that occurs extensively in eukaryotic RNA. The abnormal expression of m6A and related regulatory proteins can activate or inhibit certain signal pathways or oncogenes, thus affecting the proliferation, metastasis and prognosis of BC. Numerous studies have shown that m6A regulator disorder exists in BC, and this disorder can be reversed. Therefore, m6A is predicted as a potential therapeutic target for BC. However, the molecular mechanism of m6A RNA methylation regulating the occurrence and development of BC has not been comprehensively elucidated. In this review article, the functions of various m6A regulators and the specific mechanisms of certain regulators of the progress of BC were summarized. Furthermore, the dual role of RNA methylation in tumor progression was discussed, concluding that RNA methylation can not only lead to tumorigenesis but at times give rise to inhibition of tumor formation. In addition, further comprehensive analysis on mechanisms of m6A regulators in BC is conducive to screening effective potential targets and formulating targeted treatment strategies, which will provide new methods for the prevention and treatment of BC.

HuR facilitates miR-93-5p-induced activation of MAP3K2 translation via MAP3K2 3'UTR ARE2 in hepatocellular carcinoma

MicroRNAs (miRNAs) can positively regulate gene expression through an unconventional RNA activation mechanism involving direct targeting 3' untranslated regions (UTRs). Our prior study found miR-93-5p activates mitogen-activated protein kinase kinase kinase 2 (MAP3K2) in hepatocellular carcinoma (HCC) via its 3'UTR. However, the underlying mechanism remains elusive. Here, we identified two candidate AU-rich element (ARE) motifs (ARE1 and ARE2) adjacent to the miR-93-5p binding site located within the MAP3K2 3'UTR using AREsite2. Luciferase reporter and translation assays validated that only ARE2 participated in MAP3K2 activation. Integrative analysis revealed that human antigen R (HuR), an ARE2-associated RNA-binding protein (RBP), physically and functionally interacted with the MAP3K2 3'UTR. Consequently, an HuR-ARE2 complex was shown to facilitate miR-93-5p-mediated upregulation of MAP3K2 expression. Furthermore, bioinformatics analysis and studies of HCC cells and specimens highlighted an oncogenic role for HuR and positive HuR-MAP3K2 expression correlation. HuR is also an enhancing factor in the positive feedback circuit comprising miR-93-5p, MAP3K2, and c-Jun demonstrated in our prior study. The newly identified HuR-ARE2 involvement enriches the mechanism of miR-93-5p-driven MAP3K2 activation and suggests new therapeutic strategies warranted for exploration in HCC.

Icariin ameliorates TNF-α/IFN-γ-induced oxidative stress, inflammatory response and apoptosis of human immortalized epidermal cells through the WTAP/SERPINB4 axis

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by increased sensitivity to environmental allergens and irritants. Icariin, a natural compound extracted from the herb Epimedium, has been traditionally used for its potential anti-inflammatory and antioxidant properties. This study aimed to investigate the regulatory effects of icariin on AD-like symptoms and to elucidate its underlying mechanisms. The effects of icariin on TNF-α/IFN-γ-induced HaCaT cell injury were assessed using various assays, including cell counting kit-8 for cell viability, flow cytometry for reactive oxygen species (ROS) levels, and colorimetric assays for malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity. In addition, the study performed enzyme-linked immunosorbent assays to assess cytokines (IL-1β, IL-6, and IL-8) and chemokines (MDC, TARC, and RANTES) levels. Flow cytometry was used to quantify apoptotic rate, while a wound-healing assay was conducted to assess cell migration. The expression of WT1 associated protein (WTAP) and serpin family B member 4 (SERPINB4) at the mRNA and protein levels was determined using qRT-PCR and western blotting, respectively. The associations between WTAP and SERPINB4 were analyzed using RNA immunoprecipitation assay and m6A RNA immunoprecipitation assay. Icariin treatment significantly mitigated TNF-α/IFN-γ-induced oxidative stress, inflammatory response, and apoptosis in HaCaT cells, while also reversing the inhibitory effect on cell migration. Icariin reduced the expression of WTAP in TNF-α/IFN-γ-stimulated HaCaT cells. Overexpression of WTAP reversed the effects of icariin in TNF-α/IFN-γ-stimulated HaCaT cells. WTAP silencing inhibited the mRNA stability of SERPINB4 through the m6A modification. SERPINB4 overexpression attenuated the effects of WTAP silencing on oxidative stress, inflammatory response, apoptosis, and migration of TNF-α/IFN-γ-stimulated HaCaT cells. Icariin treatment downregulated SERPINB4 expression by regulating WTAP in TNF-α/IFN-γ-stimulated HaCaT cells. Icariin ameliorated TNF-α/IFN-γ-induced human immortalized epidermal cell injury through the WTAP/SERPINB4 axis, highlighting the potential for targeted interventions in AD pathogenesis.

Astragalus polysaccharide alleviates IL-13-induced oxidative stress injury in nasal epithelial cells by inhibiting WTAP-mediated FBXW7 m6A modification

Background

Allergic rhinitis (AR) a common and complicated upper airway disease mediated by specific IgE antibodies. Our study aims to explore the pharmacological effects of astragalus polysaccharide (APS) on AR and elucidate the mechanisms involved.

Methods

RT-qPCR and Western blotting were used to analyze mRNA and protein expression. Interleukin (IL)-13-treated human nasal epithelial cells (hNECs) was employed as the AR cell model. Cell apoptosis and viability were evaluated by TUNEL staining and MTT assay, respectively. ROS level was examined by the DCFH-DA probe. Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) levels were measured by the corresponding kits. FBXW7 m6A modification level was assessed by MeRIP assay.

Methods

Our results showed that APS treatment reduced cell apoptosis, ROS, and MDA levels while increasing SOD, CAT, and GSH-Px levels in IL-13-treated hNECs by activating the Nrf2/HO-1 pathway. Moreover, APS alleviated IL-13-induced oxidative stress injury in hNECs by downregulating WTAP. In addition, WTAP knockdown increased FBXW7 mRNA stability by regulating FBXW7 mRNA m6A modification. It also turned out that APS alleviated IL-13-induced oxidative stress injury in hNECs through the WTAP/FBXW7 axis.

Conclusions

Taken together, APS inhibited WTAP-mediated FBXW7 m6A modification to alleviate IL-13-induced oxidative stress injury in hNECs.

Insight into the regulatory mechanism of m6A modification: From MAFLD to hepatocellular carcinoma

In recent years, there has been a significant increase in the incidence of metabolic-associated fatty liver disease (MAFLD), which has been attributed to the increasing prevalence of type 2 diabetes mellitus (T2DM) and obesity. MAFLD affects more than one-third of adults worldwide, making it the most prevalent liver disease globally. Moreover, MAFLD is considered a significant risk factor for hepatocellular carcinoma (HCC), with MAFLD-related HCC cases increasing. Approximately 1 in 6 HCC patients are believed to have MAFLD, and nearly 40 % of these HCC patients do not progress to cirrhosis, indicating direct transformation from MAFLD to HCC. N6-methyladenosine (m6A) is commonly distributed in eukaryotic mRNA and plays a crucial role in normal development and disease progression, particularly in tumors. Numerous studies have highlighted the close association between abnormal m6A modification and cellular metabolic alterations, underscoring its importance in the onset and progression of MAFLD. However, the specific impact of m6A modification on the progression of MAFLD to HCC remains unclear. Can targeting m6A effectively halt the progression of MAFLD-related HCC? In this review, we investigated the pivotal role of abnormal m6A modification in the transition from MAFLD to HCC, explored the potential of m6A modification as a therapeutic target for MAFLD-related HCC, and proposed possible directions for future investigations.

Targeting FTO suppresses hepatocellular carcinoma by inhibiting ERBB3 and TUBB4A expression

Fat mass and obesity-associated protein (FTO) is an N6-methyladenosine (m6A) demethylase and plays critical oncogenic roles in multiple cancers. Here we show that FTO is an effective target in hepatocellular carcinoma (HCC). FTO is highly expressed in patients with HCC. Genetic depletion of Fto dramatically attenuated HCC progression in mice. Pharmacological inhibition of FTO by FB23/FB23-2 markedly suppressed the proliferation and migration of HCC cell lines in vitro and inhibited HCC tumorigenicity in xeno-transplanted mice. Mechanistically, FB23-2 suppressed the expression of Erb-b2 receptor tyrosine kinase 3 (ERBB3) and human tubulin beta class Iva (TUBB4A) by increasing the m6A level in these mRNA transcripts. The decrease in ERBB3 expression resulted in the inhibition of Akt-mTOR signaling, which subsequently impaired the proliferation and survival of HCC cells. Moreover, FB23-2 disturbed the stability of the tubulin cytoskeleton, whereas overexpression of TUBB4A rescued the migration of HCC cells. Collectively, our study demonstrates that FTO plays a critical role in HCC by maintaining the proliferation and migration of cells and highlights the potential of FTO inhibitors for targeting HCC.

N6-methyladenosine RNA modifications: a potential therapeutic target for AML

N6-methyladenosine (m6A) RNA modification has recently emerged as an essential regulator of normal and malignant hematopoiesis. As a reversible epigenetic modification found in messenger RNAs and non-coding RNAs, m6A affects the fate of the modified RNA molecules. It is essential in most vital bioprocesses, contributing to cancer development. Here, we review the up-to-date knowledge of the pathological functions and underlying molecular mechanism of m6A modifications in normal hematopoiesis, leukemia pathogenesis, and drug response/resistance. At last, we discuss the critical role of m6A in immune response, the therapeutic potential of targeting m6A regulators, and the possible combination therapy for AML.

The circZEB1/miR-337-3p/OGT axis mediates angiogenesis and metastasis via O-GlcNAcylation and up-regulating YBX1 in breast cancer

Background

A growing corpus of research has revealed that circular RNAs (circRNAs) have become increasingly important for the growth of malignancies in recent years. CircRNAs as ideal candidates for breast cancer (BC) therapeutic targets is still absent.

Methods

In our study, the dysregulated circRNAs in BC progression were explored, we analysed the BC's circRNA expression profiles using publicly available datasets (GSE101124 and GSE101122). The expression of circZEB1 in BC and cell lines was investigated by qPCR. RNase and actinomycin D were used to examine the features of circZEB1. The function of circZEB1 was subsequently investigated through the utilisation of colony formation, tube formation, transwell assays, and xenograft animal models.RNA immunoprecipitation (RIP), luciferase reporter assays, immunoprecipitation (co-IP) test in conjunction with LC-MS, and ChIP-seq assay to investigate the molecular mechanism underlying the biological activity of circZEB1 in BC.

Results

Among the circRNAs, we were particularly interested in hsa_circ_0000228, which is spliced from the oncogene ZEB1. In BC cell lines, CircZEB1 expression was upregulated. CircZEB1 knockdown prevented BC cells from migrating and invading, as well as HUVECs from forming tubes and developing. By sponging miR-337-3p, functional testing revealed that circZEB1 promoted O-GlcNAcylation, increased YBX1, and OGT expression. Moreover, circZEB1 overexpression is reversible, in contrast to YBX1 knockdown, which mostly results in the downregulation of multiple oncogenes.

Conclusion

Our study indicate that circZEB1 had oncogenic function in BC by focusing on circZEB1/miR-337-3p/OGT and YBX1. It might be inferred that circZEB1 could be a promising new target for BC treatment.

Progression of m6A in the tumor microenvironment: hypoxia, immune and metabolic reprogramming

Recently, N6-methyladenosine (m6A) has aroused widespread discussion in the scientific community as a mode of RNA modification. m6A comprises writers, erasers, and readers, which regulates RNA production, nuclear export, and translation and is very important for human health. A large number of studies have found that the regulation of m6A is closely related to the occurrence and invasion of tumors, while the homeostasis and function of the tumor microenvironment (TME) determine the occurrence and development of tumors to some extent. TME is composed of a variety of immune cells (T cells, B cells, etc.) and nonimmune cells (tumor-associated mesenchymal stem cells (TA-MSCs), cancer-associated fibroblasts (CAFs), etc.). Current studies suggest that m6A is involved in regulating the function of various cells in the TME, thereby affecting tumor progression. In this manuscript, we present the composition of m6A and TME, the relationship between m6A methylation and characteristic changes in TME, the role of m6A methylation in TME, and potential therapeutic strategies to provide new perspectives for better treatment of tumors in clinical work.

The role of WTAP in regulating macrophage-mediated osteoimmune responses and tissue regeneration in periodontitis

Periodontitis, delineated by the destruction of structures that support teeth, is predominantly propelled by intricate immune responses. Immunomodulatory treatments offer considerable promise for the management of this ailment; however, the modulation of the periodontal immune microenvironment to facilitate tissue regeneration presents a substantial biomedical challenge. Herein, our study investigates the role of Wilms' tumor 1-associating protein (WTAP), a critical m6A methyltransferase, in the immunomodulation of periodontitis and assesses its viability as a therapeutic target. We observed heightened expression of WTAP in macrophages extracted from gingival tissues impacted by periodontitis, with a strong association with M1 polarization. Via loss-of-function experiments, we demonstrated that diminishing WTAP expression precipitates a transition from M1 to M2 macrophage phenotypes amidst inflammatory conditions, thus improving the periodontal immune landscape. Further, RNA sequencing and indirect co-culture assays indicated that suppressing of WTAP expression modulates osteoimmune responses and enhances the osteogenic differentiation of bone marrow stromal cells. The local deployment of adeno-associated virus-shWTAP in murine models of periodontitis robustly validated the therapeutic promise of targeting WTAP in this disease. Collectively, our findings highlight the crucial role of WTAP in orchestrating macrophage-mediated osteoimmune responses and tissue regeneration in periodontitis, proposing novel avenues for immunotherapeutic interventions in its treatment.

METTL3 promotes immature dental pulp stem cells-induced angiogenesis by regulating ETS1 mRNA stability in an m6A-HuR-dependent manner

Angiogenesis serves as the determinate element of pulp regeneration. Dental pulp stem cell (DPSC) implantation can promote the regeneration of dental pulp tissue. Herein, the role of m6A methyltransferase methyltransferase-like 3 (METTL3) in regulating DPSCs-induced angiogenesis during pulp regeneration therapy was investigated. Cell DPSC viability, HUVEC migration, and angiogenesis ability were analyzed by CCK-8 assay, wound healing, Transwell assay, and tube formation assay. The global and EST1 mRNA m6A levels were detected by m6A dot blot and Me-RIP. The interactions between E26 transformation-specific proto-oncogene 1(ETS1), human antigen R(HuR), and METTL3 were analyzed by RIP assay. The relationship between METTL3 and the m6A site of ETS1 was performed by dual-luciferase reporter assay. ETS1 mRNA stability was examined with actinomycin D. Herein, our results revealed that human immature DPSCs (hIDPSCs) showed stronger ability to induce angiogenesis than human mature DPSCs (hMDPSCs), which might be related to ETS1 upregulation. ETS1 knockdown inhibited DPSCs-induced angiogenesis. Our mechanistic experiments demonstrated that METTL3 increased ETS1 mRNA stability and expression level on DPSCs in an m6A-HuR-dependent manner. ETS1 upregulation abolished sh-METTL3's inhibition on DPSCs-induced angiogenesis. METTL3 upregulation promoted DPSCs-induced angiogenesis by enhancing ETS1 mRNA stability in an m6A-HuR-dependent manner. This study reveals a new mechanism by which m6A methylation regulates angiogenesis in DPSCs, providing new insights for stem cell-based tissue engineering.

Mechanisms and clinical landscape of N6-methyladenosine (m6A) RNA modification in gastrointestinal tract cancers

Epigenetics encompasses reversible and heritable chemical modifications of non-nuclear DNA sequences, including DNA and RNA methylation, histone modifications, non-coding RNA modifications, and chromatin rearrangements. In addition to well-studied DNA and histone methylation, RNA methylation has emerged as a hot topic in biological sciences over the past decade. N6-methyladenosine (m6A) is the most common and abundant modification in eukaryotic mRNA, affecting all RNA stages, including transcription, translation, and degradation. Advances in high-throughput sequencing technologies made it feasible to identify the chemical basis and biological functions of m6A RNA. Dysregulation of m6A levels and associated modifying proteins can both inhibit and promote cancer, highlighting the importance of the tumor microenvironment in diverse biological processes. Gastrointestinal tract cancers, including gastric, colorectal, and pancreatic cancers, are among the most common and deadly malignancies in humans. Growing evidence suggests a close association between m6A levels and the progression of gastrointestinal tumors. Global m6A modification levels are substantially modified in gastrointestinal tumor tissues and cell lines compared to healthy tissues and cells, possibly influencing various biological behaviors such as tumor cell proliferation, invasion, metastasis, and drug resistance. Exploring the diagnostic and therapeutic potential of m6A-related proteins is critical from a clinical standpoint. Developing more specific and effective m6A modulators offers new options for treating these tumors and deeper insights into gastrointestinal tract cancers.

All-trans retinoic acid exhibits anti-proliferative and differentiating activity in Merkel cell carcinoma cells via retinoid pathway modulation

BACKGROUND

The limited therapies available for treating Merkel cell carcinoma (MCC), a highly aggressive skin neoplasm, still pose clinical challenges, and novel treatments are required. Targeting retinoid signalling with retinoids, such as all-trans retinoic acid (ATRA), is a promising and clinically useful antitumor approach. ATRA drives tumour cell differentiation by modulating retinoid signalling, leading to anti-proliferative and pro-apoptotic effects. Although retinoid signalling is dysregulated in MCC, ATRA activity in this tumour is unknown. This study aimed to evaluate the impact of ATRA on the pathological phenotype of MCC cells.

METHODS

The effect of ATRA was tested in various Merkel cell polyomavirus-positive and polyomavirus-negative MCC cell lines in terms of cell proliferation, viability, migration and clonogenic abilities. In addition, cell cycle, apoptosis/cell death and the retinoid gene signature were evaluated upon ATRA treatments.

RESULTS

ATRA efficiently impaired MCC cell proliferation and viability in MCC cells. A strong effect in reducing cell migration and clonogenicity was determined in ATRA-treated cells. Moreover, ATRA resulted as strongly effective in arresting cell cycle and inducing apoptosis/cell death in all tested MCC cells. Enrichment analyses indicated that ATRA was effective in modulating the retinoid gene signature in MCC cells to promote cell differentiation pathways, which led to anti-proliferative and pro-apoptotic/cell death effects.

CONCLUSIONS

These results underline the potential of retinoid-based therapy for MCC management and might open the way to novel experimental approaches with other retinoids and/or combinatorial treatments.

WTAP promotes proliferation of esophageal squamous cell carcinoma via m6A-dependent epigenetic promoting of PTP4A1

Esophageal squamous cell carcinoma (ESCC) represents a frequently seen malignancy with high prevalence worldwide. Although current studies have shown that Wilms' tumor 1-associated protein (WTAP), a major part in the methyltransferase complex, is involved in various tumor pathological processes, its specific role in ESCC remains unclear. Therefore, the present work focused on exploring WTAP's function and mechanism in ESCC progression using clinical ESCC specimens, ESCC cells, and mammalian models. Firstly, we proved WTAP was significantly upregulated within ESCC, and WTAP mRNA expression showed a good diagnostic performance for ESCC. Functionally, WTAP positively regulated in-vivo and in-vitro ESCC cells' malignant phenotype through the AKT-mTOR signaling pathway. Meanwhile, WTAP positively regulated the N6-methyladenosine (m6A) modification levels in ESCC cells. Protein tyrosine phase type IVA member 1 (PTP4A1) was confirmed to be the m6A target of WTAP, and WTAP positively regulated the expression of PTP4A1. Further study revealed that PTP4A1 showed high expression within ESCC. Silencing PTP4A1 inhibited the AKT-mTOR signaling pathway to suppress ESCC cells' proliferation. Rescue experiments showed that silencing PTP4A1 partially reversed the WTAP-promoting effect on ESCC cells' proliferation ability. Mechanistically, WTAP regulated PTP4A1 expression to activate the AKT-mTOR pathway, promoting the proliferation of ESCC cells. Our study demonstrated that WTAP regulates the progression of ESCC through the m6A-PTP4A1-AKT-mTOR signaling axis and that WTAP is a potential target for diagnosing and treating ESCC.

The m6A-independent role of epitranscriptomic factors in cancer

Protein function alteration and protein mislocalization are cancer hallmarks that drive oncogenesis. N6-methyladenosine (m6A) deposition mediated by METTL3, METTL16, and METTL5 together with the contribution of additional subunits of the m6A system, has shown a dramatic impact on cancer development. However, the cellular localization of m6A proteins inside tumor cells has been little studied so far. Interestingly, recent evidence indicates that m6A methyltransferases are not always confined to the nucleus, suggesting that epitranscriptomic factors may also have multiple oncogenic roles beyond m6A that still represent an unexplored field. To date novel epigenetic drugs targeting m6A modifiers, such as METTL3 inhibitors, are entering into clinical trials, therefore, the study of the potential onco-properties of m6A effectors beyond m6A is required. Here we will provide an overview of methylation-independent functions of the m6A players in cancer, describing the molecular mechanisms involved and the future implications for therapeutics.

The role of RNA methylation in tumor immunity and its potential in immunotherapy

RNA methylation, a prevalent post-transcriptional modification, has garnered considerable attention in research circles. It exerts regulatory control over diverse biological functions by modulating RNA splicing, translation, transport, and stability. Notably, studies have illuminated the substantial impact of RNA methylation on tumor immunity. The primary types of RNA methylation encompass N6-methyladenosine (m6A), 5-methylcytosine (m5C), N1-methyladenosine (m1A), and N7-methylguanosine (m7G), and 3-methylcytidine (m3C). Compelling evidence underscores the involvement of RNA methylation in regulating the tumor microenvironment (TME). By affecting RNA translation and stability through the "writers", "erasers" and "readers", RNA methylation exerts influence over the dysregulation of immune cells and immune factors. Consequently, RNA methylation plays a pivotal role in modulating tumor immunity and mediating various biological behaviors, encompassing proliferation, invasion, metastasis, etc. In this review, we discussed the mechanisms and functions of several RNA methylations, providing a comprehensive overview of their biological roles and underlying mechanisms within the tumor microenvironment and among immunocytes. By exploring how these RNA modifications mediate tumor immune evasion, we also examine their potential applications in immunotherapy. This review aims to provide novel insights and strategies for identifying novel targets in RNA methylation and advancing cancer immunotherapy efficacy.

HBXIP induces PARP1 via WTAP-mediated m6A modification and CEBPA-activated transcription in cisplatin resistance to hepatoma

Poly (ADP-ribose) polymerase 1 (PARP1) is a DNA-binding protein that is involved in various biological functions, including DNA damage repair and transcription regulation. It plays a crucial role in cisplatin resistance. Nevertheless, the exact regulatory pathways governing PARP1 have not yet been fully elucidated. In this study, we present evidence suggesting that the hepatitis B X-interacting protein (HBXIP) may exert regulatory control over PARP1. HBXIP functions as a transcriptional coactivator and is positively associated with PARP1 expression in tissues obtained from hepatoma patients in clinical settings, and its high expression promotes cisplatin resistance in hepatoma. We discovered that the oncogene HBXIP increases the level of PARP1 m6A modification by upregulating the RNA methyltransferase WTAP, leading to the accumulation of the PARP1 protein. In this process, on the one hand, HBXIP jointly activates the transcription factor ETV5, promoting the activation of the WTAP promoter and further facilitating the promotion of the m6A modification of PARP1 by WTAP methyltransferase, enhancing the RNA stability of PARP1. On the other hand, HBXIP can also jointly activate the transcription factor CEBPA, enhance the activity of the PARP1 promoter, and promote the upregulation of PARP1 expression, ultimately leading to enhanced DNA damage repair capability and promoting cisplatin resistance in hepatoma. Notably, aspirin inhibits HBXIP, thereby reducing the expression of PARP1. Overall, our research revealed a novel mechanism for increasing PARP1 abundance, and aspirin therapy could overcome cisplatin resistance in hepatoma.

N6-methyladenosine (m6A) Writer WTAP Potentiates Hepatocellular Carcinoma Immune Evasion and Aerobic Glycolysis

Hepatocellular carcinoma (HCC) is one of most prevalent malignant tumors with poor prognosis and a high mortality rate. Recent research indicates that N6-methyladenosine (m6A) and tumor immunotherapy are important factors in HCC. More research is still needed to fully understand the profound roles that m6A writer Wilms tumor 1-associated protein (WTAP) and CD8+ T cells play in the antitumor immunity that prevents HCC from progressing. According to the findings of our investigation, WTAP was significantly elevated in HCC cells and was associated with a poor prognosis. Functionally, WTAP accelerated HCC immune evasion and aerobic glycolysis while suppressing the tumor-killing ability of CD8+ T cells. On the other hand, WTAP knockdown had the opposite effect. WTAP targets the m6A site on the 3'-UTR of PD-L1 mRNA, which mechanistically increases the stability of PD-L1 mRNA. These results showed that WTAP inhibited CD8+ T cells' antitumor activity, which in turn deteriorated HCC immune evasion and aerobic glycolysis. In conclusion, our research uncovers a novel mechanism for WTAP on the tumor-killing ability of CD8+ T cells, which helps to overcome HCC immune evasion.

The lncRNAMALAT1-WTAP axis: a novel layer of EMT regulation in hypoxic triple-negative breast cancer

Early metastatic disease development is one characteristic that defines triple-negative breast cancer (TNBC) as the most aggressive breast cancer (BC) subtype. Numerous studies have identified long non-coding RNAs (lncRNA) as critical players in regulating tumor progression and metastasis formation. Here, we show that MALAT1, a long non-coding RNA known to promote various features of BC malignancy, such as migration and neo angiogenesis, regulates TNBC cell response to hypoxia. By profiling MALAT1-associated transcripts, we discovered that lncRNA MALAT1 interacts with the mRNA encoding WTAP protein, previously reported as a component of the N6-methyladenosine (m6A) modification writer complex. In hypoxic conditions, MALAT1 positively regulates WTAP protein expression, which influences the response to hypoxia by favoring the transcription of the master regulators HIF1α and HIF1β. Furthermore, WTAP stimulates BC cell migratory ability and the expression of N-Cadherin and Vimentin, hallmarks of epithelial-to-mesenchymal transition (EMT). In conclusion, this study highlights the functional axis comprising MALAT1 and WTAP as a novel prognostic marker of TNBC progression and as a potential target for the development of therapeutic approaches for TNBC treatment.

Regulatory roles of N6-methyladenosine (m6A) methylation in RNA processing and non-communicable diseases

Post-transcriptional RNA modification is an emerging epigenetic control mechanism in cells that is important in many different cellular and organismal processes. N6-methyladenosine (m6A) is one of the most prevalent, prolific, and ubiquitous internal transcriptional alterations in eukaryotic mRNAs, making it an important topic in the field of Epigenetics. m6A methylation acts as a dynamical regulatory process that regulates the activity of genes and participates in multiple physiological processes, by supporting multiple aspects of essential mRNA metabolic processes, including pre-mRNA splicing, nuclear export, translation, miRNA synthesis, and stability. Extensive research has linked aberrations in m6A modification and m6A-associated proteins to a wide range of human diseases. However, the impact of m6A on mRNA metabolism and its pathological connection between m6A and other non-communicable diseases, including cardiovascular disease, neurodegenerative disorders, liver diseases, and cancer remains in fragmentation. Here, we review the existing understanding of the overall role of mechanisms by which m6A exerts its activities and address new discoveries that highlight m6A's diverse involvement in gene expression regulation. We discuss m6A deposition on mRNA and its consequences on degradation, translation, and transcription, as well as m6A methylation of non-coding chromosomal-associated RNA species. This study could give new information about the molecular process, early detection, tailored treatment, and predictive evaluation of human non-communicable diseases like cancer. We also explore more about new data that suggests targeting m6A regulators in diseases may have therapeutic advantages.

Chidamide inhibits cell glycolysis in acute myeloid leukemia by decreasing N6-methyladenosine-related GNAS-AS1

BACKGROUND

Acute myeloid leukemia (AML) is a hematopoietic malignancy. Chidamide has shown anti-cancer effect in different malignancies. The function of Chidamide in glycolysis in AML cells remains unclear.

METHODS

AML cells were treated with 1000 nM Chidamide for 48 h. The levels of long non-coding RNA-GNAS-AS1, miR-34a-5p, glycolysis-related proteins, and Ras homolog gene family (RhoA)/Rho-associated protein kinase (ROCK) signaling-related proteins were detected by qRT-PCR or western blot. Cell viability and apoptosis were measured by CCK-8 and flow cytometry. Glycolysis levels were measured by assay kits. GNAS-AS1 N6-methyladenosine (m6A) modification level was detected by methylated RNA immunoprecipitation sequencing. The combined targets of miR-34a-5p were validated using a dual-luciferase reporter assay. BALB/C nude mice were selected for subcutaneous tumor validation. Chidamide at a dosage of 25 mg/kg was used in the animal study.

RESULTS

GNAS-AS1 promoted glycolysis in AML cells by upregulating the expression of glycolysis-related proteins and increasing glucose consumption, lactate production, ATP generation, and the extracellular acidification rate. Chidamide treatment suppressed WT1-associated protein (WTAP)-mediated RNA m6A modification of GNAS-AS1. Chidamide downregulated GNAS-AS1 to inhibit glycolysis in AML cells. GNAS-AS1 targeted miR-34a-5p to promote insulin-like growth factor 2 mRNA-binding protein (IGF2BP2) expression. IGF2BP2 inhibition reversed the promoting effect of miR-34a-5p knockdown on glycolysis and RhoA/ROCK pathway in Chidamide-treated cells. GNAS-AS1 overexpression abolished the inhibitory effect of Chidamide on AML tumorigenesis in vivo by modulating the RhoA/ROCK pathway.

CONCLUSION

Chidamide inhibited glycolysis in AML by repressing WTAP-mediated GNAS-AS1 m6A modification and then regulating the miR-34a-5p/IGF2BP2 axis.

METTL3 Modulates TXNIP Expression to Affect the Activation of NLRP3 Inflammasome in Hepatic Cells Under Oxygen-Glucose Deprivation/Reperfusion Injury

Hepatic ischemia-reperfusion (I/R) injury is still a major risk factor and unsolved problem in hepatic surgery. Methyltransferase-like 3 (METTL3), an important m6A-modified methylase, regulates inflammation and cellular stress response. In this study, we demonstrated the special role of METTL3 and its underlying mechanism in hepatic I/R injury. In the mouse model of hepatic I/R and in the oxygen-glucose deprivation and reoxygenation (OGD/R)-induced AML12 and NCTC 1469 cells, the expression of METTL3 was significantly upregulated. Inhibition of METTL3 in OGD/R-induced AML12 and NCTC 1469 cells both increased the cell viability, declined the cell apoptosis, and decreased the reactive oxygen species (ROS) and the release levels of interleukin-1β (IL-1β) and interleukin-18 (IL-18), diminishing NLRP3 and Caspase1-p20 expressions. Moreover, METTL3 positively modulated TXNIP expression in an m6A manner. TXNIP overexpression reversed the effects of METTL3 knockdown on OGD/R-induced injury in AML12 cells. Furthermore, inhibition of NLRP3 inflammasome activity contributed to the protective effects of TXNIP knockdown in OGD/R-induced AML12 cells. In conclusion, METTL3 knockdown alleviated OGD/R-induced hepatocyte injury, and the specific mechanism was associated with the inhibition of NLRP3 inflammasome activation, which was attributed to the reduction of TXNIP in an m6A-dependent manner.

New horizons for the role of RNA N6-methyladenosine modification in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancy, presenting a formidable challenge to the medical community owing to its intricate pathogenic mechanisms. Although current prevention, surveillance, early detection, diagnosis, and treatment have achieved some success in preventing HCC and controlling overall disease mortality, the imperative to explore novel treatment modalities for HCC remains increasingly urgent. Epigenetic modification has emerged as pivotal factors in the etiology of cancer. Among these, RNA N6-methyladenosine (m6A) modification stands out as one of the most prevalent, abundant, and evolutionarily conserved post-transcriptional alterations in eukaryotes. The literature underscores that the dynamic and reversible nature of m6A modifications orchestrates the intricate regulation of gene expression, thereby exerting a profound influence on cell destinies. Increasing evidence has substantiated conspicuous fluctuations in m6A modification levels throughout the progression of HCC. The deliberate modulation of m6A modification levels through molecular biology and pharmacological interventions has been demonstrated to exert a discernible impact on the pathogenesis of HCC. In this review, we elucidate the multifaceted biological functions of m6A modifications in HCC, and concurrently advancing novel therapeutic strategies for the management of this malignancy.

YTHDC1-dependent m6A modification modulated FOXM1 promotes glycolysis and tumor progression through CENPA in triple-negative breast cancer

Triple-negative breast cancer (TNBC) exhibits heightened aggressiveness compared with other breast cancer (BC) subtypes, with earlier relapse, a higher risk of distant metastasis, and a worse prognosis. Transcription factors play a pivotal role in various cancers. Here, we found that factor forkhead box M1 (FOXM1) expression was significantly higher in TNBC than in other BC subtypes and normal tissues. Combining the findings of Gene Ontology (GO) enrichment analysis and a series of experiments, we found that knockdown of the FOXM1 gene attenuated the ability of TNBC cells to proliferate and metastasize both in vivo and in vitro. In addition, Spearman's test showed that FOXM1 significantly correlated with glycolysis-related genes, especially centromere protein A (CENPA) in datasets (GSE76250, GSE76124, GSE206912, and GSE103091). The effect of silencing FOXM1 on the inhibition of CENPA expression, TNBC proliferation, migration, and glycolysis could be recovered by overexpression of CENPA. According to MeRIP, the level of m6A modification on FOMX1 decreased in cells treated with cycloleucine (a m6A inhibitor) compared with that in the control group. The increase in FOXM1 expression caused by YTHDC1 overexpression could be reversed by the m6A inhibitor, which indicated that YTHDC1 enhanced FOXM1 expression depending on m6A modification. Therefore, we concluded that the YTHDC1-m6A modification/FOXM1/CENPA axis plays an important role in TNBC progression and glycolysis.

RNA modifications in the progression of liver diseases: from fatty liver to cancer

Non-alcoholic fatty liver disease (NAFLD) has emerged as a prominent global health concern associated with high risk of metabolic syndrome, and has impacted a substantial segment of the population. The disease spectrum ranges from simple fatty liver to non-alcoholic steatohepatitis (NASH), which can progress to cirrhosis and hepatocellular carcinoma (HCC) and is increasingly becoming a prevalent indication for liver transplantation. The existing therapeutic options for NAFLD, NASH, and HCC are limited, underscoring the urgent need for innovative treatment strategies. Insights into gene expression, particularly RNA modifications such as N6 methyladenosine (m6A), hold promising avenues for interventions. These modifications play integral roles in RNA metabolism and cellular functions, encompassing the entire NAFLD-NASH-HCC progression. This review will encompass recent insights on diverse RNA modifications, including m6A, pseudouridine (ψ), N1-methyladenosine (m1A), and 5-methylcytidine (m5C) across various RNA species. It will uncover their significance in crucial aspects such as steatosis, inflammation, fibrosis, and tumorigenesis. Furthermore, prospective research directions and therapeutic implications will be explored, advancing our comprehensive understanding of the intricate interconnected nature of these pathological conditions.

Small molecule inhibitors targeting m6A regulators

As the most common form of epigenetic regulation by RNA, N6 methyladenosine (m6A) modification is closely involved in physiological processes, such as growth and development, stem cell renewal and differentiation, and DNA damage response. Meanwhile, its aberrant expression in cancer tissues promotes the development of malignant tumors, as well as plays important roles in proliferation, metastasis, drug resistance, immunity and prognosis. This close association between m6A and cancers has garnered substantial attention in recent years. An increasing number of small molecules have emerged as potential agents to target m6A regulators for cancer treatment. These molecules target the epigenetic level, enabling precise intervention in RNA modifications and efficiently disrupting the survival mechanisms of tumor cells, thus paving the way for novel approaches in cancer treatment. However, there is currently a lack of a comprehensive review on small molecules targeting m6A regulators for anti-tumor. Here, we have comprehensively summarized the classification and functions of m6A regulators, elucidating their interactions with the proliferation, metastasis, drug resistance, and immune responses in common cancers. Furthermore, we have provided a comprehensive overview on the development, mode of action, pharmacology and structure-activity relationships of small molecules targeting m6A regulators. Our aim is to offer insights for subsequent drug design and optimization, while also providing an outlook on future prospects for small molecule development targeting m6A.

Crosstalk between m6A modification and non-coding RNAs in HCC

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide, with high morbidity and occurrence. Although various therapeutic approaches have been rapidly developed in recent years, the underlying molecular mechanisms in the pathogenesis of HCC remain enigmatic. The N6-methyladenosine (m6A) RNA modification is believed to regulate RNA metabolism and further gene expression. This process is intricately regulated by multiple regulators, such as methylases and demethylases. Non-coding RNAs (ncRNAs) are involved in the regulation of the epigenetic modification, mRNA transcription and other biological processes, exhibiting crucial roles in tumor occurrence and development. The m6A-ncRNA interaction has been implicated in the malignant phenotypes of HCC and plays an important role in drug resistance. This review summarizes the effect of m6A-ncRNA crosstalk on HCC progression and their clinical implications as prognostic markers and therapeutic targets in this disease.

HuR-induced circ_0082319 contributes to hepatocellular carcinoma by elevating PTK2 through miR-505-3p

The aim of the present research is to explore the biological function and mechanism of circ_0082319 in HCC progression. Circ_0082319, microRNA-505-3p (miR-505-3p), protein tyrosine kinase 2 (PTK2), and human antigen R (HuR, also known as ELAVL1) level were detected by real-time quantitative polymerase chain reaction. Cell viability, proliferation, apoptosis, invasion, and angiogenesis were measured using (4-5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, transwell, and tube formation assays. Protein levels of c-Myc, MMP2, PTK2, and HuR were examined using western blot. The glycolysis levels were assessed using specific kits. Binding between miR-505-3p and circ_0082319 or PTK2 was predicted by Starbase and verified by a dual-luciferase reporter and RNA immunoprecipitation assays. The biological role of circ_0082319 on HCC tumor growth was examined using xenograft tumor model in vivo. Circ_0082319, PTK2, and HuR were highly expressed, and miR-505-3p was reduced in HCC samples and cell lines. Moreover, the knockdown of circ_0082319 might repress HCC cell proliferation, invasion, angiogenesis, and induce apoptosis in vitro. In mechanism, circ_0082319 served as a sponge of miR-505-3p to regulate PTK2 expression. HuR expedited circ_0082319 expression in HCC cells. HuR-mediated circ_0082319 might accelerate HCC cell proliferation, invasion, angiogenesis, and suppress apoptosis by the miR-505-3p/PTK2 axis, hinting at a promising therapeutic target for HCC treatment.

RNA methylation: A potential therapeutic target in autoimmune disease

Autoimmune diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and inflammatory bowel disease (IBD) are caused by the body's immune response to autoantigens. The pathogenesis of autoimmune diseases is unclear. Numerous studies have demonstrated that RNA methylation plays a key role in disease progression, which is essential for post-transcriptional regulation and has gradually become a broad regulatory mechanism that controls gene expression in various physiological processes, including RNA nuclear output, translation, splicing, and noncoding RNA processing. Here, we outline the writers, erasers, and readers of RNA methylation, including N6-methyladenosine (m6A), 2'-O-methylation (Nm), 2'-O-dimethyladenosine (m6Am), N1-methyladenosine (m1A), 5-methylcytidine (m5C) and N7-methylguanosine (m7G). As the role of RNA methylation modifications in the immune system and diseases is explained, the potential treatment value of these modifications has also been demonstrated. This review reports the relationship between RNA methylation and autoimmune diseases, highlighting the need for future research into the therapeutic potential of RNA modifications.

Novel Insights into the Links between N6-Methyladenosine and Regulated Cell Death in Musculoskeletal Diseases

Musculoskeletal diseases (MSDs), including osteoarthritis (OA), osteosarcoma (OS), multiple myeloma (MM), intervertebral disc degeneration (IDD), osteoporosis (OP), and rheumatoid arthritis (RA), present noteworthy obstacles associated with pain, disability, and impaired quality of life on a global scale. In recent years, it has become increasingly apparent that N6-methyladenosine (m6A) is a key regulator in the expression of genes in a multitude of biological processes. m6A is composed of 0.1-0.4% adenylate residues, especially at the beginning of 3'-UTR near the translation stop codon. The m6A regulator can be classified into three types, namely the "writer", "reader", and "eraser". Studies have shown that the epigenetic modulation of m6A influences mRNA processing, nuclear export, translation, and splicing. Regulated cell death (RCD) is the autonomous and orderly death of cells under genetic control to maintain the stability of the internal environment. Moreover, distorted RCDs are widely used to influence the course of various diseases and receiving increasing attention from researchers. In the past few years, increasing evidence has indicated that m6A can regulate gene expression and thus influence different RCD processes, which has a central role in the etiology and evolution of MSDs. The RCDs currently confirmed to be associated with m6A are autophagy-dependent cell death, apoptosis, necroptosis, pyroptosis, ferroptosis, immunogenic cell death, NETotic cell death and oxeiptosis. The m6A-RCD axis can regulate the inflammatory response in chondrocytes and the invasive and migratory of MM cells to bone remodeling capacity, thereby influencing the development of MSDs. This review gives a complete overview of the regulatory functions on the m6A-RCD axis across muscle, bone, and cartilage. In addition, we also discuss recent advances in the control of RCD by m6A-targeted factors and explore the clinical application prospects of therapies targeting the m6A-RCD in MSD prevention and treatment. These may provide new ideas and directions for understanding the pathophysiological mechanism of MSDs and the clinical prevention and treatment of these diseases.

Epigenetic regulation of diverse cell death modalities in cancer: a focus on pyroptosis, ferroptosis, cuproptosis, and disulfidptosis

Tumor is a local tissue hyperplasia resulted from cancerous transformation of normal cells under the action of various physical, chemical and biological factors. The exploration of tumorigenesis mechanism is crucial for early prevention and treatment of tumors. Epigenetic modification is a common and important modification in cells, including DNA methylation, histone modification, non-coding RNA modification and m6A modification. The normal mode of cell death is programmed by cell death-related genes; however, recent researches have revealed some new modes of cell death, including pyroptosis, ferroptosis, cuproptosis and disulfidptosis. Epigenetic regulation of various cell deaths is mainly involved in the regulation of key cell death proteins and affects cell death by up-regulating or down-regulating the expression levels of key proteins. This study aims to investigate the mechanism of epigenetic modifications regulating pyroptosis, ferroptosis, cuproptosis and disulfidptosis of tumor cells, explore possible triggering factors in tumor development from a microscopic point of view, and provide potential targets for tumor therapy and new perspective for the development of antitumor drugs or combination therapies.

METTL14 promotes neuroblastoma formation by inhibiting YWHAH via an m6A-YTHDF1-dependent mechanism

Neuroblastoma (NB) is a common childhood tumor with a high incidence worldwide. The regulatory role of RNA N6-methyladenosine (m6A) in gene expression has attracted significant attention, and the impact of methyltransferase-like 14 (METTL14) on tumor progression has been extensively studied in various types of cancer. However, the specific influence of METTL14 on NB remains unexplored. Using data from the Target database, our study revealed significant upregulation of METTL14 expression in high-risk NB patients, with strong correlation with poor prognosis. Furthermore, we identified ETS1 and YY1 as upstream regulators that control the expression of METTL14. In vitro experiments involving the knockdown of METTL14 in NB cells demonstrated significant inhibition of cell proliferation, migration, and invasion. In addition, suppressing METTL14 inhibited NB tumorigenesis in nude mouse models. Through MeRIP-seq and RNA-seq analyses, we further discovered that YWHAH is a downstream target gene of METTL14. Mechanistically, we observed that methylated YWHAH transcripts, particularly those in the 5' UTR, were specifically recognized by the m6A "reader" protein YTHDF1, leading to the degradation of YWHAH mRNA. Moreover, the downregulation of YWHAH expression activated the PI3K/AKT signaling pathway, promoting NB cell activity. Overall, our study provides valuable insights into the oncogenic effects of METTL14 in NB cells, highlighting its role in inhibiting YWHAH expression through an m6A-YTHDF1-dependent mechanism. These findings also suggest the potential utility of a biomarker panel for prognostic prediction in NB patients.

Comprehensive analysis of m6A modification in immune infiltration, metabolism and drug resistance in hepatocellular carcinoma

N6-methyladenosine (m6A) is important in regulating mRNA stability, splicing, and translation, and it also contributes to tumor development. However, there is still limited understanding of the comprehensive effects of m6A modification patterns on the tumor immune microenvironment, metabolism, and drug resistance in hepatocellular carcinoma (HCC). In this study, we utilized unsupervised clustering based on the expression of 23 m6A regulators to identify m6A clusters. We identified differential m6A modification patterns and characterized m6A-gene-cluster A, which exhibited poorer survival rates, a higher abundance of Treg cells, and increased expression of TGFβ in the tumor microenvironment (TME). Additionally, m6A-gene-cluster A demonstrated higher levels of glycolysis activity, cholesterol metabolism, and fatty acid biosynthesis. We also found that the m6A score was associated with prognosis and drug resistance. Patients with a low m6A score experienced worse prognoses, which were linked to an abundance of Treg cells, upregulation of TGFβ, and increased metabolic activity. HCC patients with a higher m6A score showed improved prognosis following sorafenib treatment and immunotherapy. In conclusion, we reveals the association between m6A modification patterns and the tumor immune microenvironment, metabolism, and drug resistance in HCC. Furthermore, the m6A score holds potential as a predictive factor for the efficacy of targeted therapy and immunotherapy in HCC.

WTAP-mediated N6-methyladenine Modification of circEEF2 Promotes Lung Adenocarcinoma Tumorigenesis by Stabilizing CANT1 in an IGF2BP2-dependent Manner

N6-methyladenosine (m6A) is a common posttranscriptional RNA modification and plays an important role in cancer biology. Circular RNAs (circRNAs) are also reported to participate in lung adenocarcinoma (LUAD) progression. Here, we aimed to investigate the functions of Wilms tumor 1-associating protein (WTAP) methyltransferase and circEEF2 in LUAD cell tumorigenesis, and probe whether circEEF2 functioned through WTAP-induced m6A modification and its potential mechanisms. Functional analyses were conducted by tube formation, sphere formation, 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, and transwell assays in vitro as well as tumor formation experiments in mice, respectively. The N6-methyladenine (m6A) modification in circEEF2 mRNA was determined by RNA immunoprecipitation (Me-RIP) assay. The interaction between IGF2BP2 (Insulin Like Growth Factor 2 MRNA-Binding Protein 2) and circEEF2 or Calcium-activated nucleotidase 1 (CANT1) mRNA was confirmed using RIP assay. LUAD tissues and cells showed high circEEF2 expression, and the deficiency of circEEF2 suppressed LUAD cell angiogenesis, stemness, proliferation, migration, and invasion. WTAP induced circEEF2 m6A modification. WTAP silencing repressed the oncogenic phenotypes of LUAD cells via stabilizing circEEF2 in an m6A-dependent manner. IGF2BP2 interacted with circEEF2 and CANT1, and WTAP and circEEF2 could regulate CANT1 expression through IGF2BP2. The inhibition of LUAD cell oncogenic phenotypes caused by circEEF2 deficiency was abolished by CANT1 overexpression. In addition, WTAP silencing impeded LUAD growth via modulating circEEF2 and CANT1 in vivo. WTAP-mediated m6A modification of circEEF2 promotes lung adenocarcinoma growth and tumorigenesis by stabilizing CANT1 through IGF2BP2.

Novel insights into small open reading frame-encoded micropeptides in hepatocellular carcinoma: A potential breakthrough

Traditionally, non-coding RNAs (ncRNAs) are regarded as a class of RNA transcripts that lack encoding capability; however, advancements in technology have revealed that some ncRNAs contain small open reading frames (sORFs) that are capable of encoding micropeptides of approximately 150 amino acids in length. sORF-encoded micropeptides (SEPs) have emerged as intriguing entities in hepatocellular carcinoma (HCC) research, shedding light on this previously unexplored realm. Recent studies have highlighted the regulatory functions of SEPs in the occurrence and progression of HCC. Some SEPs exhibit inhibitory effects on HCC, but others facilitate its development. This discovery has revolutionized the landscape of HCC research and clinical management. Here, we introduce the concept and characteristics of SEPs, summarize their associations with HCC, and elucidate their carcinogenic mechanisms in HCC metabolism, signaling pathways, cell proliferation, and metastasis. In addition, we propose a step-by-step workflow for the investigation of HCC-associated SEPs. Lastly, we discuss the challenges and prospects of applying SEPs in the diagnosis and treatment of HCC. This review aims to facilitate the discovery, optimization, and clinical application of HCC-related SEPs, inspiring the development of early diagnostic, individualized, and precision therapeutic strategies for HCC.

Clinical significance of RNA methylation in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a primary liver malignancy with high mortality rates and poor prognosis. Recent advances in high-throughput sequencing and bioinformatic technologies have greatly enhanced the understanding of the genetic and epigenetic changes in liver cancer. Among these changes, RNA methylation, the most prevalent internal RNA modification, has emerged as a significant contributor of the development and progression of HCC. Growing evidence has reported significantly abnormal levels of RNA methylation and dysregulation of RNA-methylation-related enzymes in HCC tissues and cell lines. These alterations in RNA methylation play a crucial role in the regulation of various genes and signaling pathways involved in HCC, thereby promoting tumor progression. Understanding the pathogenesis of RNA methylation in HCC would help in developing prognostic biomarkers and targeted therapies for HCC. Targeting RNA-methylation-related molecules has shown promising potential in the management of HCC, in terms of developing novel prognostic biomarkers and therapies for HCC. Exploring the clinical application of targeted RNA methylation may provide new insights and approaches for the management of HCC. Further research in this field is warranted to fully understand the functional roles and underlying mechanisms of RNA methylation in HCC. In this review, we described the multifaceted functional roles and potential mechanisms of RNA methylation in HCC. Moreover, the prospects of clinical application of targeted RNA methylation for HCC management are discussed, which may provide the basis for subsequent in-depth research on RNA methylation in HCC.

RNA modification-mediated mRNA translation regulation in liver cancer: mechanisms and clinical perspectives

Malignant liver cancer is characterized by rapid tumour progression and a high mortality rate, whereas the molecular mechanisms underlying liver cancer initiation and progression are still poorly understood. The dynamic and reversible RNA modifications have crucial functions in gene expression regulation by modulating RNA processing and mRNA translation. Emerging evidence has revealed that alterations in RNA modifications facilitate the selective translation of oncogenic transcripts and promote the diverse tumorigenic processes of liver cancer. In this Review, we first highlight the current progress on the functions and mechanisms underlying RNA modifications in the regulation of mRNA translation and then summarize the exciting discoveries on aberrant RNA modification-mediated mRNA translation in the regulation of tumour initiation, metastasis, metabolism, tumour microenvironment, and drug and radiotherapy resistance in liver cancer. Finally, we discuss the diagnostic and therapeutic potentials of targeting RNA modifications and mRNA translation for the clinical management of liver cancer.

WTAP Mediates NUPR1 Regulation of LCN2 Through m6A Modification to Influence Ferroptosis, Thereby Promoting Breast Cancer Proliferation, Migration and Invasion

Ferroptosis is involved in various pathophysiological diseases, including triple-negative breast cancer (TNBC). Targeting ferroptosis is considered as a novel anti-TNBC strategy. Nevertheless, the regulatory mechanism of ferroptosis during TNBC progression is unclear. Here, the role of WTAP in ferroptosis during TNBC progression  was investigated. The clinicopathological significance of WTAP, NUPR1 and LCN2 was analyzed by Kaplan-Meier method. Cell viability was assessed using MTT assay. Transwell assay was employed to analyze cell migration and invasion. GSH/GSSG and Fe2+ levels in TNBC cells were analyzed using kits. m6A level was examined using m6A dot blot assay. NUPR1 mRNA stability was analyzed using RNA degradation assay. RIP was performed to analyze the interaction between eIF3a and NURP1. Herein, our results revealed that WTAP, NUPR1 and LCN2 expressions were significantly elevated in TNBC. NUPR1 silencing inhibited TNBC cell proliferation, migration and invasion by inducing ferroptosis. NUPR1 positively regulated LCN2 expression in TNBC cells, and LCN2 knockdown induced ferroptosis to suppress TNBC cell malignant behaviors. Our molecular study further revealed that WTAP promoted NUPR1 expression in an m6A-EIF3A mediated manner. And, as expected, WTAP knockdown promoted ferroptosis to suppress TNBC cell malignant behaviors, which were abrogated by NUPR1 overexpression. WTAP upregulated LCN2 by regulation of NUPR1 m6A modification, thereby suppressing ferroptosis to contribute to accelerate TNBC progression. Our study revealed the cancer-promoting effect of WTAP, NUPR1 and LCN2 in TNBC and clarified the relevant mechanism, providing a theoretical basis for developing novel diagnostic and therapeutic strategies for TNBC.

LncRNA SNHG12 regulated by WTAP aggravated the oxygen-glucose deprivation/reperfusion-induced injury in bEnd.3 cell

OBJECTIVES

Previous studies have identified abnormal expression of lncRNA SNHG12 in ischemic stroke, but the underlying molecular mechanism remains unclear.

MATERIALS AND METHODS

Through database predictions, m6A methylation sites were found on SNHG12, suggesting post-transcriptional modification. To further elucidate the role of SNHG12 and m6A methyltransferase WTAP in oxygen-glucose deprivation/reperfusion (OGD/R)-induced damage in cerebral microvascular endothelial cells, we conducted investigations. Additionally, we examined the impact of m6A methyltransferase WTAP on SNHG12 expression.

RESULTS

Overexpressing SNHG12 in bEnd.3 cells was found to inhibit cell proliferation and promote apoptosis, as well as activate the production of reactive oxygen species and inflammatory cytokines (E-selectin, IL-6 and MCP-1), along with angiogenic proteins (VEGFA and FGFb). Conversely, SNHG12 knockdown alleviated OGD/R-induced damage to BEnd.3 cells, resulting in improved cell proliferation, reduced apoptosis, decreased ROS and LDH production, as well as diminished expression of inflammatory cytokines (E-selectin, IL-6 and MCP-1) and angiogenic proteins (VEGFA and FGFb). Furthermore, WTAP was found to positively regulate SNHG12 expression, and WTAP knockdown in bEnd.3 cells under the OGD/R conditions inhibited cell proliferation, promoted apoptosis, and increased ROS and LDH production.

CONCLUSION

These findings suggest that WTAP may play a crucial role in SNHG12-mediated OGD/R-induced damage in bEnd.3 cells. More molecular experiments are needed to further analyze its mechanism. Overall, our study helps to enrich our understanding of the dysregulation of SNHG12 in ischemic stroke.

N6-methyladenosine (m6A) modification in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the deadliest cancers of human, the tumor-related death of which ranks third among the common malignances. N6-methyladenosine (m6A) methylation, the most abundant internal modification of RNA in mammals, participates in the metabolism of mRNA and interrelates with ncRNAs. In this paper, we overviewed the complex function of m6A regulators in HCC, including regulating the tumorigenesis, progression, prognosis, stemness, metabolic reprogramming, autophagy, ferroptosis, drug resistance and tumor immune microenvironment (TIME). Furthermore, we elucidated the interplay between m6A modification and non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs). Finally, we summarized the potential of m6A regulators as diagnostic biomarkers. What's more, we reviewed the inhibitors targeting m6A enzymes as promising therapeutic targets of HCC. We aimed to help understand the function of m6A methylation in HCC systematically and comprehensively so that more effective strategies for HCC treatment will be developed.

Engagement of N6-methyladenisine methylation of Gng4 mRNA in astrocyte dysfunction regulated by CircHECW2

The N6-methyladenosine (m6A) modification is the most prevalent modification of eukaryotic mRNAs and plays a crucial role in various physiological processes by regulating the stability or function of target mRNAs. Accumulating evidence has suggested that m6A methylation may be involved in the pathological process of major depressive disorder (MDD), a common neuropsychiatric disorder with an unclear aetiology. Here, we found that the levels of the circular RNA HECW2 (circHECW2) were significantly increased in the plasma of both MDD patients and the chronic unpredictable stress (CUS) mouse model. Notably, the downregulation of circHECW2 attenuated astrocyte dysfunction and depression-like behaviors induced by CUS. Furthermore, we demonstrated that the downregulation of circHECW2 increased the expression of the methylase WTAP, leading to an increase in Gng4 expression via m6A modifications. Our findings provide functional insight into the correlation between circHECW2 and m6A methylation, suggesting that circHECW2 may represent a potential target for MDD treatment.

Emerging function of main RNA methylation modifications in the immune microenvironment of digestive system tumors

Digestive system tumors have been reported in more than 25% of all cancer cases worldwide, bringing a huge burden on the healthcare system. RNA methylation modification-an important post-transcriptional modification-has become an active research area in gene regulation. It is a dynamic and reversible process involving several enzymes, such as methyltransferases, demethylases, and methylation reader proteins. This review provides insights into the role of three major methylation modifications, namely m6A, m5C, and m1A, in the development of digestive system tumors, specifically in the development of tumor immune microenvironment (TIME) of these malignancies. Abnormal methylation modification affects immunosuppression and antitumor immune response by regulating the recruitment of immune cells and the release of immune factors. Understanding the mechanisms by which RNA methylation regulates digestive system tumors will be helpful in exploring new therapeutic targets.

WTAP regulates the production of reactive oxygen species, promotes malignant progression, and is closely related to the tumor microenvironment in glioblastoma

RNA modifications have been substantiated to regulate the majority of physiological activities in the organism, including the metabolism of reactive oxygen species (ROS), which plays an important role in cells. As for the effect of RNA modification genes on ROS metabolism in glioblastoma (GBM), it has not been studied yet. Therefore, this study aims to screen the RNA modification genes that are most related to ROS metabolism and explore their effects on the biological behavior of GBM in vitro. Here, an association between WTAP and ROS metabolism was identified by bioinformatics analysis, and WTAP was highly expressed in GBM tissue compared with normal brain tissue, which was confirmed by western blotting and immunohistochemical staining. When using a ROS inducer to stimulate GBM cells in the WTAP overexpression group, the ROS level increased more significantly and the expression levels of superoxide dismutase 1 (SOD1) and catalase (CAT) also increased. Next, colony formation assay, wound healing assay, and transwell assay were performed to investigate the proliferation, migration, and invasion of GBM cells. The results showed that WTAP, as an oncogene, promoted the malignant progression of GBM cells. Functional enrichment analysis predicted that WTAP was involved in the regulation of tumor/immune-related functional pathways. Western blotting was used to identify that WTAP had a regulatory effect on the phosphorylation of PI3K/Akt signaling. Finally, based on functional enrichment analysis, we further performed immune-related analysis on WTAP. In conclusion, this study analyzed WTAP from three aspects, which provided new ideas for the treatment of GBM.

Developing risk models and subtypes of autophagy-associated LncRNAs for enhanced prognostic prediction and precision in therapeutic approaches for liver cancer patients

Background

Limited research has been conducted on the influence of autophagy-associated long non-coding RNAs (ARLncRNAs) on the prognosis of hepatocellular carcinoma (HCC).

Methods

We analyzed 371 HCC samples from TCGA, identifying expression networks of ARLncRNAs using autophagy-related genes. Screening for prognostically relevant ARLncRNAs involved univariate Cox regression, Lasso regression, and multivariate Cox regression. A Nomogram was further employed to assess the reliability of Riskscore, calculated from the signatures of screened ARLncRNAs, in predicting outcomes. Additionally, we compared drug sensitivities in patient groups with differing risk levels and investigated potential biological pathways through enrichment analysis, using consensus clustering to identify subgroups related to ARLncRNAs.

Results

The screening process identified 27 ARLncRNAs, with 13 being associated with HCC prognosis. Consequently, a set of signatures comprising 8 ARLncRNAs was successfully constructed as independent prognostic factors for HCC. Patients in the high-risk group showed very poor prognoses in most clinical categories. The Riskscore was closely related to immune cell scores, such as macrophages, and the DEGs between different groups were implicated in metabolism, cell cycle, and mitotic processes. Notably, high-risk group patients demonstrated a significantly lower IC50 for Paclitaxel, suggesting that Paclitaxel could be an ideal treatment for those at elevated risk for HCC. We further identified C2 as the Paclitaxel subtype, where patients exhibited higher Riskscores, reduced survival rates, and more severe clinical progression.

Conclusion

The 8 signatures based on ARLncRNAs present novel targets for prognostic prediction in HCC. The drug candidate Paclitaxel may effectively treat HCC by impacting ARLncRNAs expression. With the identification of ARLncRNAs-related isoforms, these results provide valuable insights for clinical exploration of autophagy mechanisms in HCC pathogenesis and offer potential avenues for precision medicine.

MiR-186-5p prevents hepatocellular carcinoma progression by targeting methyltransferase-like 3 that regulates m6A-mediated stabilization of follistatin-like 5

Background

Hepatocellular carcinoma (HCC) is a multistep process involving sophisticated genetic, epigenetic, and transcriptional changes. However, studies on microRNA (miRNA)'s regulatory effects of N6-methyladenosine (m6A) modifications on HCC progression are limited.

Methods

Cell Counting Kit-8 (CCK-8), clone formation, and Transwell assays were used to investigate changes in cancer cell proliferation, invasion, and migration. RNA m6A levels were verified using methylated RNA immunoprecipitation. Luciferase reporter assay was used to study the potential binding between miRNAs and mRNA. A mouse tumor transplant model was established to study the changes in tumor progression.

Results

Follistatin-like 5 (FSTL5) was significantly downregulated in HCC and inhibited its further progression. Additionally, methyltransferase-like 3 (METTL3) reduced FSTL5 mRNA stability in an m6A-YTH domain family 2(YTHDF2)-dependent manner. Functional experiments revealed that METTL3 downregulation inhibited HCC progression by upregulating FSTL5 in vitro and in vivo. Luciferase reporter assay verified that miR-186-5p directly targets METTL3. Additionally, miR-186-5p inhibits the proliferation, migration, and invasion of HCC cells by downregulating METTL3 expression.

Conclusions

The miR-186-5p/METTL3/YTHDF2/FSTL5 axis may offer new directions for targeted HCC therapy.