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Background: Diabetic retinopathy (DR) is a major ocular complication of diabetes mellitus, and a significant cause of visual impairment and blindness in adults. Phosphoserine aminotransferase 1 (PSAT1) is an enzyme participating in serine synthesis, which might improve insulin signaling and insulin sensitivity. Furthermore, it has been reported that the m6A methylation in mRNA controls gene expression under many physiological and pathological conditions. Nevertheless, the influences of m6A methylation on PSAT1 expression and DR progression at the molecular level have not been reported. Methods: High-glucose (HG) was used to treat human retinal pigment epithelial cells (ARPE-19) to construct a cell injury model. PSAT1 and Methyltransferase-like 3 (METTL3) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). PSAT1, B-cell lymphoma-2 (Bcl-2), Bcl-2 related X protein (Bax), and METTL3 protein levels were examined by western blot assay. Cell viability and apoptosis were detected by Cell Counting Kit-8 (CCK-8) and TUNEL assays. Reactive oxygen species (ROS), malondialdehyde (MDA), and Glutathione peroxidase (GSH-Px) levels were examined using special assay kits. Interaction between METTL3 and PSAT1 was verified using methylated RNA immunoprecipitation (MeRIP) and dual-luciferase reporter assay. Results: PSAT1 and METTL3 levels were decreased in DR patients and HG-treated ARPE-19 cells. Upregulation of PSAT1 might attenuate HG-induced cell viability inhibition and apoptosis and oxidative stress promotion in ARPE-19 cells. Moreover, PSAT1 was identified as a downstream target of METTL3-mediated m6A modification. METTL3 might improve the stability of PSAT1 mRNA via m6A methylation. Conclusion: METTL3 might mitigate HG-induced ARPE-19 cell damage partly by regulating the stability of PSAT1 mRNA, providing a promising therapeutic target for DR. [ABSTRACT FROM AUTHOR]

Methyltransferase-like 3(METTL3), recognized as the primary N6-methyladenosine methyltransferase, influences cellular functions such as proliferation, migration, invasion, differentiation, and fate determination by regulating gene expression post-transcriptionally. Recent studies have highlighted the indispensability of METTL3 in various immune cells such as hematopoietic stem/progenitor cells, innate immune cells (monocytes, macrophages, dendritic cells), and adaptive immune cells (thymic epithelial cell, T cells, natural killer cells). However, a comprehensive summary and analysis of these findings to elucidate the relationship between METTL3 and the immune system is yet to be undertaken. Therefore, in this review, we systematically collate reports detailing themechanism underlying the role of METTL3 in regulating various immune processes and examine the modification of METTL3 and its potential implications. This review suggests that METTL3 plays an essential role in the immune system, ranging from maintaining homeostasis to regulating functions. Collectively, this review provides a comprehensive analysis of the relationship between METTL3 and the immune system, serving convenient researchers to understand the frontiers of immunological research and facilitate future clinical applications. [ABSTRACT FROM AUTHOR]

BACKGROUND: Hyperhomocysteinemia is closely related to the function of islet β cells, but its specific molecular mechanism is not fully understood. OBJECTIVE: To investigate the role of N6 methyltransferase-like 3 (METTL3) in homocysteine (Hcy)-induced autophagy of mouse islet β cells. METHODS: The 3rd and 4th generation mouse islet β cells were taken for the experiment. (1) Cell modeling and grouping: cells in control group were not treated with Hcy, while those in homocysteine group were treated with 100 µmol/L Hcy for 48 hours. (2) The mouse islet β-cells were transfected with the plasmids overexpressing Ad-METTL3 and si-METTL3 according to the instructions of LipofectamineTM 2000. Three different interfering fragments were designed, and the one with the best interfering efficiency was verified and screened by PCR. (3) After transfection, the cells were divided into control group, Hcy group, Ad-NC (negative control)+Hcy group, Ad-METTL3+Hcy group, si-NC (negative control)+Hcy group and si-METTL3+Hcy group. (4) qRT-PCR and western blot were used to detect the expression levels of METTL3 and autophagy-related proteins LC3II/I and p62 in cells. Insulin level was determined by ELISA to evaluate insulin secretion capacity of islet cells. Autophagy-related proteins and insulin level were detected after overexpression and interference with METTL3. RESULTS AND CONCLUSION: Compared with the control group, the expression level of LC3II/I was increased (P < 0.05), the expression of p62 was significantly reduced (P < 0.05), and the insulin secretion capacity was significantly decreased (P < 0.05) in the Hcy group. Compared with the control group, the protein and mRNA levels of METTL3 were reduced in the Hcy group (P < 0.05). After METTL3 silencing in islet β cells, Hcy further upregulated the expression of LC3II/I (P < 0.05), significantly dowregulated the expression of p62 (P < 0.05), and increased the insulin level (P < 0.05). After overexpression of METTL3, Hcy significantly decreased the LC3II/I expression and increased the p62 expression in islet β cells (P < 0.05). To conclude, METTL3 is involved in the Hcy-induced autophagy regulation of islet β cells and plays a role in the regulation of insulin secretion. [ABSTRACT FROM AUTHOR]

Abstract Background Diabetic retinopathy (DR) is a major ocular complication of diabetes mellitus, and a significant cause of visual impairment and blindness in adults. Phosphoserine aminotransferase 1 (PSAT1) is an enzyme participating in serine synthesis, which might improve insulin signaling and insulin sensitivity. Furthermore, it has been reported that the m6A methylation in mRNA controls gene expression under many physiological and pathological conditions. Nevertheless, the influences of m6A methylation on PSAT1 expression and DR progression at the molecular level have not been reported. Methods High-glucose (HG) was used to treat human retinal pigment epithelial cells (ARPE-19) to construct a cell injury model. PSAT1 and Methyltransferase-like 3 (METTL3) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). PSAT1, B-cell lymphoma-2 (Bcl-2), Bcl-2 related X protein (Bax), and METTL3 protein levels were examined by western blot assay. Cell viability and apoptosis were detected by Cell Counting Kit-8 (CCK-8) and TUNEL assays. Reactive oxygen species (ROS), malondialdehyde (MDA), and Glutathione peroxidase (GSH-Px) levels were examined using special assay kits. Interaction between METTL3 and PSAT1 was verified using methylated RNA immunoprecipitation (MeRIP) and dual-luciferase reporter assay. Results PSAT1 and METTL3 levels were decreased in DR patients and HG-treated ARPE-19 cells. Upregulation of PSAT1 might attenuate HG-induced cell viability inhibition and apoptosis and oxidative stress promotion in ARPE-19 cells. Moreover, PSAT1 was identified as a downstream target of METTL3-mediated m6A modification. METTL3 might improve the stability of PSAT1 mRNA via m6A methylation. Conclusion METTL3 might mitigate HG-induced ARPE-19 cell damage partly by regulating the stability of PSAT1 mRNA, providing a promising therapeutic target for DR.

Abstract Background The pathogenesis of acute lung injury (ALI) involves a severe inflammatory response, leading to significant morbidity and mortality. N6-methylation of adenosine (m6A), an abundant mRNA nucleotide modification, plays a crucial role in regulating mRNA metabolism and function. However, the precise impact of m6A modifications on the progression of ALI remains elusive. Methods ALI models were induced by either intraperitoneal injection of lipopolysaccharide (LPS) into C57BL/6 mice or the LPS-treated alveolar type II epithelial cells (AECII) in vitro. The viability and proliferation of AECII were assessed using CCK-8 and EdU assays. The whole-body plethysmography was used to record the general respiratory functions. M6A RNA methylation level of AECII after LPS insults was detected, and then the “writer” of m6A modifications was screened. Afterwards, we successfully identified the targets that underwent m6A methylation mediated by METTL3, a methyltransferase-like enzyme. Last, we evaluated the regulatory role of METTL3-medited m6A methylation at phosphatase and tensin homolog (Pten) in ALI, by assessing the proliferation, viability and inflammation of AECII. Results LPS induced marked damages in respiratory functions and cellular injuries of AECII. The m6A modification level in mRNA and the expression of METTL3, an m6A methyltransferase, exhibited a notable rise in both lung tissues of ALI mice and cultured AECII cells subjected to LPS treatment. METTL3 knockdown or inhibition improved the viability and proliferation of LPS-treated AECII, and also reduced the m6A modification level. In addition, the stability and translation of Pten mRNA were enhanced by METTL3-mediated m6A modification, and over-expression of PTEN reversed the protective effect of METTL3 knockdown in the LPS-treated AECII. Conclusions The progression of ALI can be attributed to the elevated levels of METTL3 in AECII, as it promotes the stability and translation of Pten mRNA through m6A modification. This suggests that targeting METTL3 could offer a novel approach for treating ALI.

Abstract Breast cancer (BC) is a highly prevalent malignancy worldwide, with complex pathogenesis and treatment challenges. Research reveals that methyltransferase-like 3 (METTL3) is widely involved in the pathogenesis of several tumors through methylation of its target RNAs, and its role and mechanisms in BC are also extensively studied. In this review, we aim to provide a comprehensive interpretation of available studies and elucidate the relationship between METTL3 and BC. This review suggests that high levels of METTL3 are associated with the pathogenesis, poor prognosis, and drug resistance of BC, suggesting METTL3 as a potential diagnostic or prognostic biomarker and therapeutic target. Collectively, this review provides a comprehensive understanding of how METTL3 functions through RNA methylation, which provides a valuable reference for future fundamental studies and clinical applications.

Background: The pathogenesis of acute lung injury (ALI) involves a severe inflammatory response, leading to significant morbidity and mortality. N6-methylation of adenosine (m6A), an abundant mRNA nucleotide modification, plays a crucial role in regulating mRNA metabolism and function. However, the precise impact of m6A modifications on the progression of ALI remains elusive. Methods: ALI models were induced by either intraperitoneal injection of lipopolysaccharide (LPS) into C57BL/6 mice or the LPS-treated alveolar type II epithelial cells (AECII) in vitro. The viability and proliferation of AECII were assessed using CCK-8 and EdU assays. The whole-body plethysmography was used to record the general respiratory functions. M6A RNA methylation level of AECII after LPS insults was detected, and then the "writer" of m6A modifications was screened. Afterwards, we successfully identified the targets that underwent m6A methylation mediated by METTL3, a methyltransferase-like enzyme. Last, we evaluated the regulatory role of METTL3-medited m6A methylation at phosphatase and tensin homolog (Pten) in ALI, by assessing the proliferation, viability and inflammation of AECII. Results: LPS induced marked damages in respiratory functions and cellular injuries of AECII. The m6A modification level in mRNA and the expression of METTL3, an m6A methyltransferase, exhibited a notable rise in both lung tissues of ALI mice and cultured AECII cells subjected to LPS treatment. METTL3 knockdown or inhibition improved the viability and proliferation of LPS-treated AECII, and also reduced the m6A modification level. In addition, the stability and translation of Pten mRNA were enhanced by METTL3-mediated m6A modification, and over-expression of PTEN reversed the protective effect of METTL3 knockdown in the LPS-treated AECII. Conclusions: The progression of ALI can be attributed to the elevated levels of METTL3 in AECII, as it promotes the stability and translation of Pten mRNA through m6A modification. This suggests that targeting METTL3 could offer a novel approach for treating ALI. [ABSTRACT FROM AUTHOR]

Breast cancer (BC) is a highly prevalent malignancy worldwide, with complex pathogenesis and treatment challenges. Research reveals that methyltransferase-like 3 (METTL3) is widely involved in the pathogenesis of several tumors through methylation of its target RNAs, and its role and mechanisms in BC are also extensively studied. In this review, we aim to provide a comprehensive interpretation of available studies and elucidate the relationship between METTL3 and BC. This review suggests that high levels of METTL3 are associated with the pathogenesis, poor prognosis, and drug resistance of BC, suggesting METTL3 as a potential diagnostic or prognostic biomarker and therapeutic target. Collectively, this review provides a comprehensive understanding of how METTL3 functions through RNA methylation, which provides a valuable reference for future fundamental studies and clinical applications. [ABSTRACT FROM AUTHOR]

N6‐methylated adenosine (m6A) is a crucial RNA modification in eukaryotes, particularly in cancer. However, its role in cervical cancer (CC) is unclear. We aimed to elucidate the part of m6A in CC by analyzing methyltransferase‐like 3 (METTL3) expression, identifying downstream targets, and exploring the underlying mechanism. We assessed METTL3 expression in CC using western blotting, quantitative polymerase chain reaction (qPCR), and immunohistochemistry. In vitro and in vivo experiments examined METTL3's role in CC. We employed RNA sequencing, methylated RNA immunoprecipitation sequencing, qPCR, and RNA immunoprecipitation qPCR to explore METTL3's mechanism in CC. METTL3 expression was upregulated in CC, promoting cell proliferation and metastasis. METTL3 knockdown inhibited human cervical cancer by inactivating AKT/mTOR signaling pathway. METTL3‐mediated m6A modification was observed in CC cells, targeting phosphodiesterase 3A (PDE3A). METTL3 catalyzed m6A modification on PDE3A mRNA through YTH domain family protein 3 (YTHDF3). Our study indicated the mechanism of m6A modification in CC and suggested the METTL3/YTHDF3/PDE3A axis as a potential clinical target for CC treatment. [ABSTRACT FROM AUTHOR]

Follicular cysts are a common reproductive disorder in domestic animals that cause considerable economic losses to the farming industry. Effective prevention and treatment methods are lacking because neither the pathogenesis nor formation mechanisms of follicular cysts are well‐understood. In this study, we first investigated the granulosa cells (GCs) of cystic follicles isolated from pigs. We observed a significant reduction in the expression of methyltransferase‐like 3 (METTL3). Subsequent experiments revealed that METTL3 downregulation in GCs caused a decrease in m6A modification of pri‐miR‐21. This reduction further inhibited DGCR8 recognition and binding to pri‐miR‐21, dampening the synthesis of mature miR‐21‐5p. Additionally, the decrease in miR‐21‐5p promotes IL‐1β expression in GCs. Elevated IL‐1β activates the NFκB pathway, in turn upregulating apoptotic genes TNFa and BAX/BCL2. The subsequent apoptosis of GCs and inhibition of autophagy causes downregulation of CYP19A1 expression. These processes lower oestrogen secretion and contribute to follicular cyst formation. In conclusion, our findings provide a foundation for understanding and further exploring the mechanisms of follicular‐cyst development in farm animals. This work has important implications for treating ovarian disorders in livestock and could potentially be extended to humans. [ABSTRACT FROM AUTHOR]

Objective To investigate the mechanism by which methyltransferase-like 3 (METTL3) is involved in diabetes-induced endothelial cell apoptosis by promoting the N6-methyladenine (m6A) modification of forkhead box O (FOXO) 3 and its expression. Methods A model of advanced glycosylation end products (AGE)-induced damage in human aortic endothelial cells (HAEC) was constructed. HAEC were divided into 6 groups: cell control group, cell AGE group, cell control+negative control small interfering RNA (siRNA) group, cell AGE+negative control siRNA group, cell AGE+FOXO3 siRNA group, and cell AGE+METTL3 siRNA group, and 3 parallel groups were set in each group. The m6A modification profiles were detected and analyzed by methylated RNA immunoprecipitation sequencing (MeRIP-Seq) and bioinformatics techniques. The m6A modification level of FOXO3 mRNA was detected by RNA-binding protein immunoprecipitation (RIP). Apoptosis was detected by flow cytometry. Real-time quantitative polymerase chain reaction (RT-PCR) was used to detect the expression level of FOXO3 mRNA, and Western blotting was used to detect the expression level of FOXO3, METTL3. Six 6-week-old ApoE knockout male mice were divided into simple atherosclerosis group and diabetic atherosclerosis group by randomized numerical table method. The protein expression of mouse FOXO3, METTL3 was detected by Western blotting, and the expression of mouse FOXO3 and METTL3 in endothelial cells was detected by immunofluorescence co-localization. Two independent samples t-test was used for intergroup comparison. Results Total m6A modification and m6A modification of FOXO3 were significantly higher in the cellular AGE group compared with the cellular control group (P<0.001), and the protein expression of FOXO3 and METTL3 was significantly higher (P<0.05). Protein expression of FOXO3 and METTL3 was significantly elevated in endothelial cells in the aortic plaque region of diabetic atherosclerotic mice compared with that of mice with simple atherosclerosis (P<0.05). Apoptosis was significantly reduced in the cell AGE+FOXO3 siRNA group compared to the cell AGE+negative control siRNA group (P<0.01). The m6A modification of FOXO3 (P<0.001) and FOXO3 protein expression were significantly decreased (P<0.05) and apoptosis was significantly reduced (P<0.001) in the cellular AGE+METTL3 siRNA group compared with the cellular AGE+negative control siRNA group. Conclusion AGE induces significant changes in m6A modification in HAEC, METTL3 is involved in diabetes-induced apoptosis in vascular endothelial cells by promoting m6A modification of FOXO3 mRNA and regulating its expression. [ABSTRACT FROM AUTHOR]

Lung diseases have complex pathogenesis and treatment challenges, showing an obvious increase in the rate of diagnosis and death every year. Therefore, elucidating the mechanism for their pathogenesis and treatment ineffective from novel views is essential and urgent. Methyltransferase-like 3 (METTL3) is a novel post-transcriptional regulator for gene expression that has been implicated in regulating lung diseases, including that observed in chronic conditions such as pulmonary fibrosis (PF), pulmonary arterial hypertension (PAH), and chronic obstructive pulmonary disease (COPD), as well as acute conditions such as pneumonia, severe acute respiratory syndrome coronavirus 2 infection, and sepsis-induced acute respiratory distress syndrome. Notably, a comprehensive summary and analysis of findings from these studies might help understand lung diseases from the novel view of METTL3-regulated mechanism, however, such a review is still lacking. Therefore, this review aims to bridge such shortage by summarising the roles of METTL3 in lung diseases, establishing their interrelationships, and elucidating the potential applications of METTL3 regarding diagnosis, treatment, and prognosis. The analysis collectively suggests METTL3 is contributable to the onset and progression of these lung diseases, thereby prospecting METTL3 as a valuable biomarker for their diagnosis, treatment, and prognosis. In conclusion, this review offers elucidation into the correlation between METTL3 and lung diseases in both research and clinical settings and highlights potential avenues for exploring the roles of METTL3 in the respiratory system.

Follicle-stimulating hormone (FSH) accelerates osteoporosis in postmenopausal women, while the underlying mechanism remains uncharacterized. N6-methyladenosine (m6A) is one of the most important regulations in the development of osteoporosis. In this study, we aimed to investigate the role of FSH in m6A modification and osteoclast function. Here, we showed that FSH upregulated m6A levels in osteoclasts via stimulating methyltransferase-like 3 (METTL3) protein expression. FSH enhanced osteoclast migration, while the knockdown of METTL3 eliminated this enhancement. Both MeRIP-seq and RNA sequencing identified that cathepsin K (CTSK) is the potential downstream target of METTL3. Knockdown of CTSK reduced FSH-upregulated osteoclast migration. Furthermore, silencing METTL3 decreased CTSK mRNA stability. Finally, FSH induced phosphorylation of cyclic-AMP response element-binding protein (CREB), while silencing of CREB attenuated the effects of FSH on the promoter transcriptional activity of Mettl3 and CTSK/METTL3 protein. Taken together, these findings indicate that FSH promotes osteoclast migration via the CREB/METTL3/CTSK signaling pathway, which may provide a potential target for suppressing osteoclast mobility and postmenopausal osteoporosis therapy. [ABSTRACT FROM AUTHOR]

Objective: The feature of Parkinson's disease (PD) is the heavy dopaminergic neuron loss of substantia nigra pars compacta (SNpc), while glutaredoxin (GLRX) has been discovered to modulate the death of dopaminergic neurons. In this context, this study was implemented to uncover the impact of GRX1 on motor dysfunction and dopamine neuron degeneration in PD mice and its potential mechanism. Methods: A PD mouse model was established via injection with 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) into mice. After gain‐ and loss‐of‐function assays in mice, motor coordination was assessed using rotarod, pole, and open‐field tests, and neurodegeneration in mouse SNpc tissues was determined using immunohistochemistry of tyrosine hydroxylase and Nissl staining. NRF1, methyltransferase‐like 3 (METTL3), and GLRX expression in SNpc tissues were evaluated using qRT‐PCR, Western blot, and immunohistochemistry. The N6‐methyladenosine (m6A) levels of GLRX mRNA were examined using MeRIP. The relationship among NRF1, METTL3, and GLRX was determined by RIP, ChIP, and dual luciferase assays. Results: Low GLRX, METTL3, and NRF1 expression were observed in MPTP‐induced mice, accompanied by decreased m6A modification level of GLRX mRNA. GLRX overexpression alleviated motor dysfunction and dopamine neuron degeneration in MPTP‐induced mice. METTL3 promoted m6A modification and IGF2BP2‐dependent stability of GLRX mRNA, and NRF1 increased METTL3 expression by binding to METTL3 promoter. NRF1 overexpression increased m6A modification of GLRX mRNA and repressed motor dysfunction and dopamine neuron degeneration in MPTP‐induced mice, which was counteracted by METTL3 knockdown. Conclusion: Conclusively, NRF1 constrained motor dysfunction and dopamine neuron degeneration in MPTP‐induced PD mice by activating the METTL3/GLRX axis. [ABSTRACT FROM AUTHOR]

Several studies have highlighted the functional indispensability of methyltransferase‐like 3 (METTL3) in the reproductive system. However, a review that comprehensively interprets these studies and elucidates their relationships is lacking. Therefore, the present work aimed to review studies that have investigated the functions of METTL3 in the reproductive system (including spermatogenesis, follicle development, gametogenesis, reproductive cancer, asthenozoospermia and assisted reproduction failure). This review suggests that METTL3 functions not only essential for normal development, but also detrimental in the occurrence of disorders. In addition, promising applications of METTL3 as a diagnostic or prognostic biomarker and therapeutic target for reproductive disorders have been proposed. Collectively, this review provides comprehensive interpretations, novel insights, potential applications and future perspectives on the role of METTL3 in regulating the reproductive system, which may be a valuable reference for researchers and clinicians. [ABSTRACT FROM AUTHOR]

Cerebral ischemic stroke (CIS) is the main cause of disability. METTL3 is implicated in CIS, and we explored its specific mechanism. Middle cerebral artery occlusion (MCAO) rat model and oxygen–glucose deprivation/reperfusion (OGD/R) HAPI cell model were established and treated with LV-METTL3 or DAA, oe-METTL3, miR-335-3p mimics, or DAA, to assess their effects on MCAO rat neurological and motor function, cerebral infarction area, brain water content, microglial activation, blood–brain barrier (BBB) permeability, and NLRP3 inflammasome activation. METTL3, pri-miR-335-3p, mature miR-335-3p, and miR-335-3p mRNA levels were assessed by RT-qPCR; M1/M2 microglial phenotype proportion and M1/M2 microglia ratio, inflammatory factor levels, and m6A modification were assessed. MCAO rats manifested cerebral ischemia injury. METTL3 was under-expressed in CIS. METTL3 overexpression inhibited microglial activation and M1 polarization and BBB permeability in MCAO rats and inhibited OGD/R-induced microglial activation and reduced M1 polarization. METTL3 regulated miR-335-3p expression and inhibited NLRP3 inflammasome activation. m6A methylation inhibition averted METTL3’s effects on NLRP3 activation, thus promoting microglial activation in OGD/R-induced cells and METTL3’s effects on BBB permeability in MCAO rats. Briefly, METTL3 regulated miR-335-3p expression through RNA m6A methylation and inhibited NLRP3 inflammasome activation, thus repressing microglial activation, BBB permeability, and protecting against CIS. [ABSTRACT FROM AUTHOR]

Background and objective Lung cancer is a major threat to human health. The molecular mechanisms related to the occurrence and development of lung cancer are complex and poorly known. Exploring molecular markers related to the development of lung cancer is helpful to improve the effect of early diagnosis and treatment. Long non-coding RNA (lncRNA) THAP7-AS1 is known to be highly expressed in gastric cancer, but has been less studied in other cancers. The aim of the study is to explore the role and mechanism of methyltransferase-like 3 (METTL3) mediated up-regulation of N6-methyladenosine (m6A) modified lncRNA THAP7-AS1 expression in promoting the development of lung cancer. Methods Samples of 120 lung cancer and corresponding paracancerous tissues were collected. LncRNA microarrays were used to analyze differentially expressed lncRNAs. THAP7-AS1 levels were detected in lung cancer, adjacent normal tissues and lung cancer cell lines by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The diagnostic value of THAP7-AS1 in lung cancer and the relationship between THAP7-AS1 expression and survival rate and clinicopathological parameters were analyzed. Bioinformatics analysis, methylated RNA immunoprecipitation (meRIP), RNA pull-down and RNA-immunoprecipitation (RIP) assay were used to investigate the molecular regulation mechanism of THAP7-AS1. Cell proliferation, migration, invasion and tumorigenesis of SPC-A-1 and NCI-H1299 cells were determined by MTS, colony-formation, scratch, Transwell and xenotransplantation in vivo, respectively. Expression levels of phosphoinositide 3-kinase/protein kenase B (PI3K/AKT) signal pathway related protein were detected by Western blot. Results Expression levels of THAP7-AS1 were higher in lung cancer tissues and cell lines (P

Aim. N6-methyladenosine (m6A) RNA methylation exerts a regulatory effect on endometrioid ovarian cancer (EOC), but the specific m6A regulator genes in EOC remain to be explored. This study investigated that sulforaphene (Sul) is implicated in EOC development by regulating methyltransferase-like 3 (METTL3). Methods. The dysregulated m6A RNA methylation genes in EOC were determined by methylated RNA immunoprecipitation (MeRIP-seq) and RNA sequencing. The roles of METTL3 and/or Sul on viability, proliferative ability, cell cycle, and apoptosis of EOC cells were determined by MTT, colony formation, flow cytometry, and TUNEL staining assay, respectively. The expression of METTL3 and apoptosis-related proteins in EOC cells was detected by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot assays. Results. Five m6A RNA methylation regulators (METTL3, ELF3, IGF2BP2, FTO, and METTL14) were differentially expressed in EOC, among which METTL3 had the highest expression level. Silencing METTL3 reduced the clonal expansion and viability of EOC cells, and caused the cells to arrest in the G0/G1 phase. This also promoted apoptosis in the EOC cells and activated the FAS/FADD and mitochondrial apoptosis pathways. In contrast, overexpressing METTL3 had the opposite effect. Sul, in a dosedependent manner, reduced the viability of EOC cells but promoted their apoptosis. Sul also increased the levels of IGF2BP2 and FAS, while decreasing the levels of KRT8 and METTL3. Furthermore, Sul was able to reverse the effects of METTL3 overexpression on EOC cells. Conclusions. Sul could suppress cell proliferation and promote apoptosis of EOC cells by inhibiting the METTL3 to activate the FAS/FADD and apoptosis-associated pathways. [ABSTRACT FROM AUTHOR]

Summary: Background: Chemoresistance is a critical factor contributing to poor prognosis in clinical patients with cancer undergoing postoperative adjuvant chemotherapy. The role of gut microbiota in mediating resistance to tumour chemotherapy remains to be investigated. Methods: Patients with CRC were categorised into clinical benefit responders (CBR) and no clinical benefit responders (NCB) based on chemotherapy efficacy. Differential bacterial analysis using 16S rRNA sequencing revealed Desulfovibrio as a distinct microbe between the two groups. Employing a syngeneic transplantation model, we assessed the effect of Desulfovibrio on chemotherapy by measuring tumour burden, weight, and Ki-67 expression. We further explored the mechanisms underlying the compromised chemotherapeutic efficacy of Desulfovibrio using metabolomics, western blotting, colony formation, and cell apoptosis assays. Findings: In comparison, Desulfovibrio was more abundant in the NCB group. In vivo experiments revealed that Desulfovibrio colonisation in the gut weakened the efficacy of FOLFOX. Treatment with Desulfovibrio desulfuricans elevates serum S-adenosylmethionine (SAM) levels. Interestingly, SAM reduced the sensitivity of CRC cells to FOLFOX, thereby promoting the growth of CRC tumours. These experiments suggest that SAM promotes the growth and metastasis of CRC by driving the expression of methyltransferase-like 3 (METTL3). Interpretation: A high abundance of Desulfovibrio in the intestines indicates poor therapeutic outcomes for postoperative neoadjuvant FOLFOX chemotherapy in CRC. Desulfovibrio drives the manifestation of METTL3 in CRC, promoting resistance to FOLFOX chemotherapy by increasing the concentration of SAM. Funding: This study is supported by Wuxi City Social Development Science and Technology Demonstration Project (N20201005).

Methyltransferase-like 3 (METTL3), a component of the RNA N6-methyladenosine (m6A) modification with a specific catalytic capacity, controls gene expression by actively regulating RNA splicing, nuclear export, stability, and translation, determines the fate of RNAs and assists in regulating biological processes. Studies conducted in recent decades have demonstrated the pivotal regulatory role of METTL3 in liver disorders, including hepatic lipid metabolism disorders, liver fibrosis, nonalcoholic steatohepatitis, and liver cancer. Although METTL3’s roles in these diseases have been extensively investigated, the regulatory network of METTL3 and its potential applications remain unexplored. In this review, we provide a comprehensive overview of the roles and mechanisms of METTL3 implicated in these diseases, establish a regulatory network of METTL3, evaluate the potential for targeting METTL3 for diagnosis and treatment, and discuss avenues for future development and research. We found relatively upregulated expressions of METTL3 in these liver diseases, demonstrating its potential as a diagnostic biomarker and therapeutic target.

Abstract Background Endometriosis-related infertility is a common worldwide reproductive health concern. Despite ongoing research, the causes of infertility remain unclear. Evidence suggests that epigenetic regulation is crucial in reproduction. However, the role of N6-methyladenosine (m6A) modification of RNA in endometriosis-related infertility requires further investigation. Methods We examined the expression of m6A and methyltransferase-like 3 (METTL3) in endometrial samples taken from normal fertile women in the proliferative phase (the NP group) or the mid-secretory phase (the NS group) or from women with endometriosis-related infertility at the mid-secretory phase (the ES group). We treated primary endometrial stromal cells (ESCs) with medroxyprogesterone acetate and 8-Bromo-cyclic adenosine monophosphate for in vitro decidualization and detected the expression of m6A, METTL3, and decidual markers. We analyzed the expression of m6A, METTL3, and forkhead box O1 (FOXO1) in ESCs from normal fertile women (the ND group) or women with endometriosis-related infertility (the ED group). We also assessed the expression of m6A, METTL3, and decidual markers, as well as the embryo adhesion rate, upon METTL3 overexpression or knockdown. Additionally, we investigated the role of METTL3 in embryo implantation in vivo by applying mice with endometriosis. Furthermore, we performed RNA stability assays, RNA immunoprecipitation (RIP), and methylated RIP assays to explore the mechanisms underlying the regulation of FOXO1 by METTL3-mediated m6A. Results The expression of m6A and METTL3 was reduced only in the NS group; the NP and ES groups demonstrated increased m6A and METTL3 levels. m6A and METTL3 levels decreased in ESCs with prolonged decidual treatment. Compared to the ND group, m6A and METTL3 levels in the ED group increased after decidual treatment, whereas the expression of FOXO1 decreased. METTL3 overexpression suppressed the expression of decidual markers and embryo implantation in vitro; METTL3 knockdown exhibited the opposite effect. Inhibition of METTL3 promoted embryo implantation in vivo. Furthermore, we observed that METTL3-mediated m6A regulated the degradation of FOXO1 mRNA through YTHDF2, a m6A binding protein. Conclusions METTL3-regulated m6A promotes YTHDF2-mediated decay of FOXO1 mRNA, thereby affecting cellular decidualization and embryo implantation. These findings provide novel insights into the development of therapies for women with endometriosis-related infertility.

Background: Endometriosis-related infertility is a common worldwide reproductive health concern. Despite ongoing research, the causes of infertility remain unclear. Evidence suggests that epigenetic regulation is crucial in reproduction. However, the role of N6-methyladenosine (m6A) modification of RNA in endometriosis-related infertility requires further investigation. Methods: We examined the expression of m6A and methyltransferase-like 3 (METTL3) in endometrial samples taken from normal fertile women in the proliferative phase (the NP group) or the mid-secretory phase (the NS group) or from women with endometriosis-related infertility at the mid-secretory phase (the ES group). We treated primary endometrial stromal cells (ESCs) with medroxyprogesterone acetate and 8-Bromo-cyclic adenosine monophosphate for in vitro decidualization and detected the expression of m6A, METTL3, and decidual markers. We analyzed the expression of m6A, METTL3, and forkhead box O1 (FOXO1) in ESCs from normal fertile women (the ND group) or women with endometriosis-related infertility (the ED group). We also assessed the expression of m6A, METTL3, and decidual markers, as well as the embryo adhesion rate, upon METTL3 overexpression or knockdown. Additionally, we investigated the role of METTL3 in embryo implantation in vivo by applying mice with endometriosis. Furthermore, we performed RNA stability assays, RNA immunoprecipitation (RIP), and methylated RIP assays to explore the mechanisms underlying the regulation of FOXO1 by METTL3-mediated m6A. Results: The expression of m6A and METTL3 was reduced only in the NS group; the NP and ES groups demonstrated increased m6A and METTL3 levels. m6A and METTL3 levels decreased in ESCs with prolonged decidual treatment. Compared to the ND group, m6A and METTL3 levels in the ED group increased after decidual treatment, whereas the expression of FOXO1 decreased. METTL3 overexpression suppressed the expression of decidual markers and embryo implantation in vitro; METTL3 knockdown exhibited the opposite effect. Inhibition of METTL3 promoted embryo implantation in vivo. Furthermore, we observed that METTL3-mediated m6A regulated the degradation of FOXO1 mRNA through YTHDF2, a m6A binding protein. Conclusions: METTL3-regulated m6A promotes YTHDF2-mediated decay of FOXO1 mRNA, thereby affecting cellular decidualization and embryo implantation. These findings provide novel insights into the development of therapies for women with endometriosis-related infertility. [ABSTRACT FROM AUTHOR]

Objective To study the mechanism of m6a methyltransferase METL3 mediated proliferation, migration and invasion of pituitary neuroendocrine tumor cells by regulating the expression of KAI1/CD82. Methods The expression levels of METTL3 and KAI1/CD82 in rat pituitary cells, rat pituitary tumor cell lines GH3, and MMQ were determined by qPCR and Western blot assay. GH3 cells were cultured in vitro and randomly divided into the control group, the METL3 overexpression plasmid group, the METL3 empty plasmid group, the METL3 siRNA group and the METL3 siRNA negative control group. After grouping and transfection, the expression levels of METL3 and KAI1/CD82 of each cell group were detected by qPCR and Western blot assay. The cell viability of each group was detected by CCK-8 experiment. The cell migration and invasion in each group were detected by cell scratch and Transwell invasion experiment. The methylation modification of KAI1/CD82 m6A in each group was detected by methylated RNA immunoprecipitation (MeRIP) experiment. Results Compared with rat pituitary cells, the METL3 protein and mRNA expression level in rat pituitary tumor cell lines GH3 and MMQ were significantly increased (P＜0.05). KAI1/CD82 protein and mRNA expression levels were significantly reduced (P＜0.05). There were no significant differences in cell indicators between the control group, the METTL3 empty plasmid group and the METTL3 siRNA negative control group (P＞0.05). Compared with the control group and the METTL3 empty plasmid group, the cell viability, migration distance, number of invaded cells, METL3 protein and mRNA expression level, KAI1/CD82 m6A methylation level increased in the METL3 overexpression plasmid group (P＜0.05), and the KAI1/ CD82 protein and mRNA expression levels decreased (P＜0.05). Compared with the control group and the METTL3 siRNA negative control group, the cell viability, migration distance, number of invaded cells, METTL3 protein and mRNA expression level and KAI1/CD82 m6A methylation level decreased in the METTL3 siRNA group (P＜0.05), and KAI1/CD82 protein and mRNA expression levels increased (P＜0.05). Conclusion Down-regulating the expression of METTL3 can reduce the level of KAI1/CD82 m6A methylation, promote the transcriptional expression of KAI1/CD82 mRNA, reduce the proliferation, invasion and migration of pituitary tumor cells, and inhibit the occurrence and development of pituitary tumors. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) is related to gut microbiota dysbiosis, especially butyrate‐producing bacteria reduction. Our previous study suggested that administration of Clostridium butyricum, a butyrate‐producing bacterium, exerts a crucial effect against CRC, however the potential mechanism is not clear. We first found that methyltransferase‐like 3 (METTL3) showed a positive correlation with proliferation, epithelial–mesenchymal transition (EMT), DNA repair, metastasis, and invasion in a database analysis. The expression of METTL3 gradually increased from human normal colon tissue, to adenoma, and carcinoma, and was positively correlated with E‐cadherin and CD34 levels. Overexpression of METTL3 promoted the proliferation, migration, and invasion of CRC cells and induced vasculogenic mimicry (VM) formation. Clostridium butyricum could downregulate METTL3 expression in CRC cells and decrease the expression of vimentin and vascular endothelial growth factor receptor 2 to reduce EMT and VM formation. Clostridium butyricum alleviated the pro‐oncogenic effect of METTL3 overexpressing plasmid in CRC cells. The anti‐EMT effect on METTL3 reduction of C. butyricum could be blunted by knocking down G‐protein coupled receptor 43. Moreover, C. butyricum prevented EMT and VM and inhibited tumor metastasis in nude mice. Accordingly, C. butyricum could inhibit EMT and VM formation of intestinal carcinogenesis through downregulating METTL3. These findings broaden our understanding of probiotics supplement in CRC prevention and treatment. [ABSTRACT FROM AUTHOR]

Abstract Background Cytoplasmic activation/proliferation-associated protein-1 (Caprin-1) is implicated in cancer cell proliferation and tumorigenesis; however, its role in the development of esophageal carcinoma (ESCA) has not been examined. Methods Biological methods and data analysis were used to investigate the expression of Caprin-1 in ESCA tissue and cell lines. We comprehensively analyzed the mRNA expression and prognostic values, signalling pathways of CAPRIN1 in ESCA using public databases online. Biological functions of CAPRIN1 were performed by clorimetric growth assay, EdU staining, colony formation, flow cytometry, apoptosis analysis, Western blot, lactate detection assay, extracellular acidification rates. The underlying mechanism was determined via flow cytometric analysis, Western blot and rescue experiments. In addition, xenograft tumor model was constructed to verify the phenotypes upon CAPRIN1 silencing. Results Caprin-1 expression was significantly elevated in both ESCA tumor tissues and cell lines compared with that in normal adjacent tissues and fibroblasts. Increased CAPRIN1 mRNA expression was significantly associated with clinical prognosis and diagnostic accuracy. The GO enrichment and KEGG pathway analysis CAPRIN1 might be related to immune-related terms, protein binding processes, and metabolic pathways. A significant positive correlation was observed between high Caprin-1 protein levels and lymph node metastasis (P = 0.031), ki-67 (P = 0.023), and 18F- FDG PET/CT parameters (SUVmax (P = 0.002) and SUV mean (P = 0.005)) in 55 ESCA patients. At cut-off values of SUVmax 17.71 and SUVmean 10.14, 18F- FDG PET/CT imaging predicted Caprin-1 expression in ESCA samples with 70.8% sensitivity and 77.4% specificity. In vitro and in vivo assays showed that Caprin-1 knockdown affected ESCA tumor growth. Silencing Caprin-1 inhibited ESCA cell proliferation and glycolysis, and decreased the expression of methyltransferase-like 3 (METTL3) and Wilms’ tumor 1-associating protein (WTAP). However, this effect could be partially reversed by the restoration of METTL3 and WTAP expression. Conclusions Our data suggest that Caprin-1 could serve as a prognostic biomarker and has an oncogenic role in ESCA.

OBJECTIVE: N6-methyladenosine (m6A) is one of the most abundant post-transcriptional modifications in eukaryotic RNA. As m6A modifications play an important role in RNA processing, abnormal m6A regulation caused by aberrant expression of m6A regulators is closely related to carcinogenesis. In this study, we aimed to determine the role of METTL3 expression in carcinogenesis, regulation of splicing factor expression by METTL3, and their effects in survival period and cancer-related metabolisms. MATERIALS AND METHODS: We investigated the correlation between each splicing factor and METTL3 in breast invasive ductal carcinoma (BRCA), colon adenocarcinoma (COAD), lung adenocarcinoma (LUAD) and gastric adenocarcinoma (STAD). Survival analysis was performed based on the expression of each splicing factor. To determine the molecular mechanism of SRSF11 in carcinogenesis, gene set enrichment analysis using RNA sequencing data was performed according to SRSF11 expression. RESULTS: Among the 64 splicing factors used for correlation analysis, 13 splicing factors showed a positive correlation with METTL3 in all four cancer types. We found that when METTL3 expression was decreased, the expression of SRSF11 was also decreased in all four types of cancer tissue when compared to that in normal tissue. Decreased SRSF11 expression was associated with poor survival in patients with BRCA, COAD, LUAD, and STAD. Gene set enrichment analysis according to SRSF11 expression showed that the p53/apoptosis, inflammation/immune response, and ultraviolet/reactive oxygen species stimulus-response pathways were enriched in cancers with decreased SRSF11 expression. CONCLUSIONS: These results suggest that METTL3 regulates SRSF11 expression, which could influence mRNA splicing in m6A modified cancer cells. METTL3-mediated downregulation of SRSF11 expression in cancer patients correlates with poor prognosis. [ABSTRACT FROM AUTHOR]

Background: Oral squamous cell carcinoma (OSCC), a main type of squamous cell cancer, is associated with considerable morbidity and mortality. Recent reports suggested methyltransferase‐like 3 (METTL3)‐mediated N6‐methyladenosine (m6A) modification to be an essential regulator in the fate determination of stem cells. However, the functional significance of METTL3 in OSCC remains largely unknown. Methods: METTL3 expression was examined in OSCC patient samples, followed by correlation analysis against clinical tumor features. Functional assays, such as assessment of surface marker expression, colony forming, BrdU incorporation, tumor xenograft assay, and m6A dot blot, were conducted to study the impact of METTL3 knockdown (KD) in OSCC cells. Results: High METTL3 expression was positively correlated with more severe clinical features of OSCC tumors. METTL3 KD caused impairment of stem‐like capacities in OSCC cells, such as tumorigenicity in vivo and colony‐forming ability in vitro. Furthermore, METTL3‐KD and cycloleucine, a methylation inhibitor, decreased m6A levels and down‐regulated p38 expression in OSCC cells. On the contrary, the impaired cell proliferation capacity of OSCC cells after METTL3‐KD was restored by exogenous expression of p38. Conclusion: Our findings identified m6A methyltransferase METTL3 as a key element in the regulation of tumorigenesis in OSCC. [ABSTRACT FROM AUTHOR]

Background: Cytoplasmic activation/proliferation-associated protein-1 (Caprin-1) is implicated in cancer cell proliferation and tumorigenesis; however, its role in the development of esophageal carcinoma (ESCA) has not been examined. Methods: Biological methods and data analysis were used to investigate the expression of Caprin-1 in ESCA tissue and cell lines. We comprehensively analyzed the mRNA expression and prognostic values, signalling pathways of CAPRIN1 in ESCA using public databases online. Biological functions of CAPRIN1 were performed by clorimetric growth assay, EdU staining, colony formation, flow cytometry, apoptosis analysis, Western blot, lactate detection assay, extracellular acidification rates. The underlying mechanism was determined via flow cytometric analysis, Western blot and rescue experiments. In addition, xenograft tumor model was constructed to verify the phenotypes upon CAPRIN1 silencing. Results: Caprin-1 expression was significantly elevated in both ESCA tumor tissues and cell lines compared with that in normal adjacent tissues and fibroblasts. Increased CAPRIN1 mRNA expression was significantly associated with clinical prognosis and diagnostic accuracy. The GO enrichment and KEGG pathway analysis CAPRIN1 might be related to immune-related terms, protein binding processes, and metabolic pathways. A significant positive correlation was observed between high Caprin-1 protein levels and lymph node metastasis (P = 0.031), ki-67 (P = 0.023), and 18F- FDG PET/CT parameters (SUVmax (P = 0.002) and SUV mean (P = 0.005)) in 55 ESCA patients. At cut-off values of SUVmax 17.71 and SUVmean 10.14, 18F- FDG PET/CT imaging predicted Caprin-1 expression in ESCA samples with 70.8% sensitivity and 77.4% specificity. In vitro and in vivo assays showed that Caprin-1 knockdown affected ESCA tumor growth. Silencing Caprin-1 inhibited ESCA cell proliferation and glycolysis, and decreased the expression of methyltransferase-like 3 (METTL3) and Wilms' tumor 1-associating protein (WTAP). However, this effect could be partially reversed by the restoration of METTL3 and WTAP expression. Conclusions: Our data suggest that Caprin-1 could serve as a prognostic biomarker and has an oncogenic role in ESCA. [ABSTRACT FROM AUTHOR]

Abstract Background Chemoresistance serves as a huge obstacle for acute myeloid leukemia (AML) patients. To counteract the chemoresistance in AML cells, we discussed the role of maternally expressed gene 3 (MEG3) in arabinocytosine (AraC) chemoresistance in AML cells. Methods MEG3, microRNA (miR)-493-5p, methyltransferase-like 3 (METTL3) and MYC expression in AML cells was determined and then their interactions were also analyzed. Then, the viability and apoptosis of AML cells were determined through loss- and gain- function assay. The level of m6A modification in AML cells was examined. AML mouse models were also established to validate the potential roles of MEG3. Results MEG3 and miR-493-5p were downregulated in AML cells, and they were lower in resistant cells than in parental cells. MEG3 led to elevated expression of miR-493-5p which targeted METTL3. METTL3 increased expression of MYC by promoting its m6A levels. Overexpression of MEG3 and miR-493-5p or knockdown of METTL3 inhibited HL-60 and Molm13 cell proliferation and promoted their apoptosis. Overexpressed MEG3 induced heightened sensitivity of AML cells to AraC. However, the suppression of miR-493-5p reversed the effects of overexpressed MEG3 on AML cells. Conclusions Collectively, MEG3 could upregulate miR-493-5p expression and suppress the METTL3/MYC axis through MYC m6A methylation, by which MEG3 promoted the chemosensitivity of AML cells.

Lung cancer is one of the leading causes of death among cancer patients worldwide. Carbon‐ion radiotherapy is a radical nonsurgical treatment with high local control rates and no serious adverse events. N6‐methyladenosine (m6A) modification is one of the most common chemical modifications in eukaryotic messenger RNA (mRNA) and has important effects on the stability, splicing, and translation of mRNAs. Recently, the regulatory role of m6A in tumorigenesis has been recognized more and more. However, the dysregulation of m6A and its role in carbon‐ion radiotherapy of non‐small‐cell lung cancer (NSCLC) remains unclear. In this study, we found that the level of methyltransferase‐like 3 (METTL3) and its mediated m6A modification were elevated in NSCLC cells with carbon‐ion radiotherapy. Knockdown of METTL3 in NSCLC cells impaired proliferation, migration, and invasion in vitro and in vivo. Moreover, we found that METTL3‐mediated m6A modification of mRNA inhibited the decay of H2A histone family member X (H2AX) mRNA and enhanced its expression, which led to enhanced DNA damage repair and cell survival. [ABSTRACT FROM AUTHOR]

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Background : Accumulating evidence shows that N6 -methyladenosine (m6A) modulators contribute to the process of chronic pain. However, the exact mechanisms of m6A writers involved in visceral hypersensitivity of Irritable bowel syndrome (IBS) remain unclear. This article aimed to reveal a new mechanism for the progression of IBS. Methods : The IBS-like model was established by neonatal colorectal distention (CRD). The relationship between m6A and circKcnk9 was analyzed by bioinformatics, immunofluorescence and RNA fluorescence in situ hybridization (FISH) assays. Visceral hypersensitivity was assessed based on the electromyography (EMG) response of the abdominal external oblique muscle to CRD. In vivo and in vitro studies (including EMG stereotactic infusion, Western blot and qRT-PCR) were utilized to explore the biological functions of related indicators. The bioinformatics, RIP experiments and RNA pull-down assays were used to explore the potential molecular mechanisms. Results : We identified that neonatal CRD increased the level of the m6A via methyltransferase-like 3 (METTL3) in the hippocampal neurons. Subsequently, knockdown of METTL3 could alleviate visceral hypersensitivity in IBS-like rats. By contrast, overexpression of METTL3 could induce visceral hypersensitivity and activate hippocampal neurons in control rats. Moreover, YTHDC1, the only m6A-associated protein predicted by bioinformatics to bind to circKcnk9, modulated visceral hypersensitivity through regulating the nuclear export of circKcnk9 in an m6A-dependent manner. Notably, FISH data suggested that the increased nuclear staining of circKcnk9 caused by siYTHDC1 could be recovered by overexpression of YTHDC1 wild type (WT) but not YTHDC1 negative control (NC) in PC12 cells. Conclusions : Our findings reveal a new regulatory mechanism in progress of IBS, that is, METTL3 modulates visceral hypersensitivity through regulating the nuclear export of circKcnk9 in YTHDC1-dependent manner. [ABSTRACT FROM AUTHOR]

Objective: Lung cancer (LC) remains a threatening health issue worldwide. Methyltransferase-like protein 3 (METTL3) is imperative in carcinogenesis via m6A modification of microRNAs (miRNAs). This study estimated the effect of METTL3 in LC by regulating m6A methylation-mediated pri-miR-663 processing. Methods: miR-663 expression in 4 LC cell lines and normal HBE cells was determined using RT-qPCR. A549 and PC9 LC cells selected for in vitro studies were transfected with miR-663 mimics or inhibitor. Cell viability, migration, invasion, proliferation, and apoptosis were detected by CCK-8, Transwell, EdU, and flow cytometry assays. The downstream target genes and binding sites of miR-663 were predicted via Starbase database and validated by dual-luciferase assay. LC cells were delivered with oe-METTL3/sh-METTL3. Crosslinking between METTL3 and DGCR8 was verified by co-immunoprecipitation. Levels of m6A, miR-663, and pri-miR-663 were measured by m6A dot blot assay and RT-qPCR. m6A modification of pri-miR-663 was verified by Me-RIP assay. Finally, the effects of METTL3 in vivo were ascertained by tumor xenograft in nude mice. Results: miR-663 was upregulated in LC cells, and miR-663 overexpression promoted cell proliferation, migration, invasion, and inhibited apoptosis, but miR-663 knockdown exerted the opposite effects. miR-663 repressed SOCS6 expression. SOCS6 overexpression annulled the promotion of miR-663 on LC cell growth. METTL3 bound to DGCR8, and METTL3 silencing elevated the levels of pri-miR-663 and m6A methylation-modified pri-miR-663, and suppressed miR-663 maturation and miR-663 expression. METTL3 facilitated tumor growth in mice through the miR-663/SOCS6 axis. Conclusion: METTL3 promotes LC progression by accelerating m6A methylation-mediated pri-miR-663 processing and repressing SOCS6. [ABSTRACT FROM AUTHOR]

Background: Methyltransferase-like 3 (METTL3) is an RNA N6-methyladenosine (m6A) methyltransferase, which plays a critical role in micorRNA (miRNAs) processing and maturation, but it is still unclear whether METTL3 regulated miRNAs participates in the regulation of cancer aggressiveness in gastrointestinal stromal tumors (GISTs). Objectives: This study was designed to investigate this issue, and uncover the potential underlying mechanisms. Methods: the expression of METTL3 in GISTs tissues and cell lines were determined by RT-qPCR and Western blot. Cell proliferation and migration were assessed by colony formation, CCK-8 and Transwell. The mRNA expression of all proteins was detected by RT-qPCR, and tumor xenograft study was applied to confirm the effect of METTL3 on GISTs development in vivo. Results: In our study, we showed that METTL3 was significantly upregulated in GISTs tissues and cell lines. Functional experiments demonstrated that overexpression of METTL3 promoted GISTs cell malignant biological behavior and tumor growth in vitro and in vivo, and conversely, silencing of METTL3 had opposite effects and suppressed GISTs progression. Further mechanistical experiments verified that METTL3 promoted the maturation of miR-25-3p in an m6A-dependent manner. Similar to METTL3, miR-25-3p was also validated as an oncogene to promote cancer development in GISTs. Finally, our rescuing experiments hinted that silencing of miR-25-3p abrogated the tumor-initiating effects of METTL3 overexpression on GISTs. Conclusion: Collectively, those results indicated that METTL3 played an oncogenic role in GISTs through positively modulating the miR-25-3p in an m6A-dependent manner, and we firstly discussed how the METTL3/m6A/miR-25-3p axis affected GISTs development. [ABSTRACT FROM AUTHOR]

Background: Arecoline is known as the main active carcinogen found in areca nut extract that drives the pathological progression of oral squamous cell carcinoma (OSCC). Studies have revealed that dysregulation of RNA N6-methyladenosine (m6A) methyltransferase components is intimately linked to cancer initiation and progression, including oral cancer. Methods: The arecoline-induced dysregulated methyltransferase-like 3 (METTL3) gene was identified using RNA-seq transcriptome assay. Using in vitro and in vivo models, the biological roles of METTL3 in arecoline-transformed oral cancer were examined. Results: We found that METTL3 was markedly elevated in arecoline-exposed OSCC cell lines and OSCC tissues of areca nut chewers. We identified that hypoxia-inducible factor 1-alpha (HIF-1α) stimulated METTL3 expression at the transcriptional level and further proved that METTL3-MYC-HIF-1α formed a positive autoregulation loop in arecoline-transformed OSCC cells. Subsequently, we manifested that METTL3 depletion profoundly reduced cell proliferation, cell migration, oncogenicity, and cisplatin resistance of arecoline-exposed OSCC cells. Conclusions: Developing novel strategies to target METTL3 may be a potential way to treat OSCC patients, particularly those with areca nut chewing history and receiving cisplatin treatment. [ABSTRACT FROM AUTHOR]

Lung diseases have complex pathogenesis and treatment challenges, showing an obvious increase in the rate of diagnosis and death every year. Therefore, elucidating the mechanism for their pathogenesis and treatment ineffective from novel views is essential and urgent. Methyltransferase-like 3 (METTL3) is a novel post-transcriptional regulator for gene expression that has been implicated in regulating lung diseases, including that observed in chronic conditions such as pulmonary fibrosis (PF), pulmonary arterial hypertension (PAH), and chronic obstructive pulmonary disease (COPD), as well as acute conditions such as pneumonia, severe acute respiratory syndrome coronavirus 2 infection, and sepsis-induced acute respiratory distress syndrome. Notably, a comprehensive summary and analysis of findings from these studies might help understand lung diseases from the novel view of METTL3-regulated mechanism, however, such a review is still lacking. Therefore, this review aims to bridge such shortage by summarising the roles of METTL3 in lung diseases, establishing their interrelationships, and elucidating the potential applications of METTL3 regarding diagnosis, treatment, and prognosis. The analysis collectively suggests METTL3 is contributable to the onset and progression of these lung diseases, thereby prospecting METTL3 as a valuable biomarker for their diagnosis, treatment, and prognosis. In conclusion, this review offers elucidation into the correlation between METTL3 and lung diseases in both research and clinical settings and highlights potential avenues for exploring the roles of METTL3 in the respiratory system. [Display omitted] • METTL3 triggers chronic lung disease via regulating inflammation response. • METTL3 induces the occurrence of pneumonia and exacerbates its progression. • METTL3 modulates SARS-CoV-2 replication. • METTL3 facilitates endothelial barrier dysfunction and inflammation in ARDS. [ABSTRACT FROM AUTHOR]

Abstract Background Colorectal carcinoma (CRC) is the third most common cancer and second most common cause of cancer-related deaths worldwide. Ribonucleic acid (RNA) N6-methyladnosine (m6A) and methyltransferase-like 3 (METTL3) play key roles in cancer progression. However, the roles of m6A and METTL3 in CRC progression require further clarification. Methods Adenoma and CRC samples were examined to detect m6A and METTL3 levels, and tissue microarrays were performed to evaluate the association of m6A and METTL3 levels with the survival of patients with CRC. The biological functions of METTL3 were investigated through cell counting kit-8, wound healing, and transwell assays. M6A epitranscriptomic microarray, methylated RNA immunoprecipitation-qPCR, RNA stability, luciferase reporter, and RNA immunoprecipitation assays were performed to explore the mechanism of METTL3 in CRC progression. Results M6A and METTL3 levels were substantially elevated in CRC tissues, and patients with CRC with a high m6A or METTL3 levels exhibited shorter overall survival. METTL3 knockdown substantially inhibited the proliferation, migration, and invasion of CRC cells. An m6A epitranscriptomic microarray revealed that the cell polarity regulator Crumbs3 (CRB3) was the downstream target of METTL3. METTL3 knockdown substantially reduced the m6A level of CRB3, and inhibited the degradation of CRB3 mRNA to increase CRB3 expression. Luciferase reporter assays also showed that the transcriptional level of wild-type CRB3 significantly increased after METTL3 knockdown but not its level of variation. Knockdown of YT521-B homology domain–containing family protein 2 (YTHDF2) substantially increased CRB3 expression. RNA immunoprecipitation assays also verified the direct interaction between the YTHDF2 and CRB3 mRNA, and this direct interaction was impaired after METTL3 inhibition. In addition, CRB3 knockdown significantly promoted the proliferation, migration, and invasion of CRC cells. Mechanistically, METTL3 knockdown activated the Hippo pathway and reduced nuclear localization of Yes1-associated transcriptional regulator, and the effects were reversed by CRB3 knockdown. Conclusions M6A and METTL3 levels were substantially elevated in CRC tissues relative to normal tissues. Patients with CRC with high m6A or METTL3 levels exhibited shorter overall survival, and METTL3 promoted CRC progression. Mechanistically, METTL3 regulated the progression of CRC by regulating the m6A–CRB3–Hippo pathway.

Circular RNA is crucial for the development of multiple malignant tumors including colorectal cancer. Circular RNA lamin B1 has recently been verified to accelerate colorectal cancer progression. However, it is not clear whether circular RNA lamin B1 can be regulated by the main methylase (methyltransferaselike 3) in colorectal cancer. This study was to explore the mechanism of methyltransferase-like 3-mediated epigenetic reactivation of circular RNA lamin B1 in colorectal cancer. We first analyzed the expression and correlation between methyltransferase-like 3 and circular RNA lamin B1 in colorectal cancer tissues, and then assessed the effects of methyltransferase-like 3 and circular RNA lamin B1 on the malignant properties of colorectal cancer cells by conducting loss-of-function and restoration studies. We also examined the growth and pathological structures in colorectal cancer xenograft tumors, as well as the levels of methyltransferase-like 3, circular RNA lamin B1 and caspase 3 expression in colorectal cancer xenograft tumors by reverse transcription-quantitative polymerase chain reaction, western blotting, hematoxylin and eosin staining and immunohistochemistry. Our results showed that the levels of circular RNA lamin B1 and methyltransferase-like 3 expressions were elevated and positively correlated in colorectal cancer tissues. Functionally, methyltransferase-like 3 silencing could prevent colorectal cancer cell proliferation, migration and invasion, and facilitate apoptosis in colorectal cancer cells by downregulating circular RNA lamin B1. Moreover, we found that knockdown of methyltransferase-like 3 could prevent tumor growth and disrupt the histological structure of colorectal cancer xenograft tumors by reducing circular RNA lamin B1 expression. Our data confirmed that methyltransferase-like 3 knockdown could attenuate the development of colorectal cancer cells by lowering circular RNA lamin B1 expression. This suggests circular RNA lamin B1 as a novel oncogene in colorectal cancer, which could be regulated by methyltransferaselike 3. Methyltransferase-like 3 silencing and circular RNA lamin B1 might be of great significance in colorectal cancer therapy. [ABSTRACT FROM AUTHOR]

Methyltransferase-like 3(METTL3), recognized as the primary N 6 -methyladenosine methyltransferase, influences cellular functions such as proliferation, migration, invasion, differentiation, and fate determination by regulating gene expression post-transcriptionally. Recent studies have highlighted the indispensability of METTL3 in various immune cells such as hematopoietic stem/progenitor cells, innate immune cells (monocytes, macrophages, dendritic cells), and adaptive immune cells (thymic epithelial cell, T cells, natural killer cells). However, a comprehensive summary and analysis of these findings to elucidate the relationship between METTL3 and the immune system is yet to be undertaken. Therefore, in this review, we systematically collate reports detailing the mechanism underlying the role of METTL3 in regulating various immune processes and examine the modification of METTL3 and its potential implications. This review suggests that METTL3 plays an essential role in the immune system, ranging from maintaining homeostasis to regulating functions. Collectively, this review provides a comprehensive analysis of the relationship between METTL3 and the immune system, serving convenient researchers to understand the frontiers of immunological research and facilitate future clinical applications., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Zhang, Gou, Qu and Su.)

Background: Chemoresistance serves as a huge obstacle for acute myeloid leukemia (AML) patients. To counteract the chemoresistance in AML cells, we discussed the role of maternally expressed gene 3 (MEG3) in arabinocytosine (AraC) chemoresistance in AML cells.Methods: MEG3, microRNA (miR)-493-5p, methyltransferase-like 3 (METTL3) and MYC expression in AML cells was determined and then their interactions were also analyzed. Then, the viability and apoptosis of AML cells were determined through loss- and gain- function assay. The level of m6A modification in AML cells was examined. AML mouse models were also established to validate the potential roles of MEG3.Results: MEG3 and miR-493-5p were downregulated in AML cells, and they were lower in resistant cells than in parental cells. MEG3 led to elevated expression of miR-493-5p which targeted METTL3. METTL3 increased expression of MYC by promoting its m6A levels. Overexpression of MEG3 and miR-493-5p or knockdown of METTL3 inhibited HL-60 and Molm13 cell proliferation and promoted their apoptosis. Overexpressed MEG3 induced heightened sensitivity of AML cells to AraC. However, the suppression of miR-493-5p reversed the effects of overexpressed MEG3 on AML cells.Conclusions: Collectively, MEG3 could upregulate miR-493-5p expression and suppress the METTL3/MYC axis through MYC m6A methylation, by which MEG3 promoted the chemosensitivity of AML cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • Silencing METTL3 led to a decreased m6A modification in the 5′UTR of AMIGO2 pre-mRNA. • YTHDC1 interacted with m6A-modified pre-mRNA of AMIGO2 to regulate its splicing. • AMIGO2 was a downstream target of both METTL3 and YTHDC1. • AMIGO2 contributed to the malignant behaviors of ESCC cells in vitro and in vivo. • The METTL3-m6A-YTHDC1-AMIGO2 axis might play critical role in ESCC. The upregulation of methyltransferase-like 3 (METTL3) has been associated with the progression of esophageal cancer. However, METTL3-induced N6-methyladenosine (m6A) alterations on the downstream target mRNAs in esophageal squamous cell carcinoma (ESCC) are not yet fully understood. Our study revealed that silencing METTL3 resulted in a significant decrease in ESCC cell proliferation and metastasis in vitro and in vivo. Additionally, the adhesion molecule with Ig like domain 2 (AMIGO2) was identified as a potential downstream target of both METTL3 and YTH Domain-Containing Protein 1 (YTHDC1) in ESCC cells. Functionally, AMIGO2 augmented the malignant behaviors of ESCC cells in vitro and in vivo , and its overexpression can rescue the inhibition of the proliferation and migration in ESCC cells induced by METTL3 or YTHDC1 knockdown. Furthermore, our findings revealed that knockdown of METTL3 decreased m6A modification in the 5′-untranslated regions (5′UTR) of AMIGO2 precursor mRNA (pre-mRNA), and YTHDC1 interacted with AMIGO2 pre-mRNA to regulate AMIGO2 expression by modulating the splicing process of AMIGO2 pre-mRNA in ESCC cells. These findings highlighted a novel role of the METTL3-m6A-YTHDC1-AMIGO2 axis in regulating ESCC cell proliferation and motility, suggesting its potential as a therapeutic target for ESCC. [ABSTRACT FROM AUTHOR]

Background and Aim: Colorectal cancer (CRC) is one of the major health issues in the world. Circ_0000677 has been shown to be upregulated in CRC with unclarified function and mechanism. Methyltransferase‐like 3 (METTL3) acts as a regulator for gene expression via the mechanism of RNA N6‐methyladenosine (m6A) in different types of cancer, which is under the control of SUMO1‐based SUMOylation. We aim to investigate their roles in CRC progression. Methods: Quantitative real‐time polymerase chain reaction and Western blot were used to detect the expressions of METTL3, circ_0000677, and ATP binding cassette subfamily c member 1(ABCC1) in CRC patients' tissues and cell lines. The functions of ABCC1 and circ_0000677 in CRC were studied by manipulating their level via knocking down or overexpression. RNA pull‐down and RNA immunoprecipitation assays were performed to identify the specific binding of target genes. The biological function of SUMOylation of METTL3 was investigated in vivo by xenograft mice tumor model. Results: METTL3, circ_0000677, and ABCC1 were upregulated in CRC patients' samples and cell lines. Circ_0000677 positively regulates CRC cell proliferation and drug resistance via affecting ABCC1 expression. METTL3 facilitated circ_0000677 level via m6A modification. METTL3 was regulated by SUMO1‐mediated SUMOylation in CRC. Mutation of METTL3‐K459 could suppress tumor growth in vivo via regulating circ_0000677/ABCC1 axis. Conclusions: Overall, our study revealed that circ_0000677 and its downstream target ABCC1 were upregulated in CRC cells, induced by the METTL3‐mediated m6A modification of circ_0000677 and SUMO1‐mediated SUMOylation of METTL3. This work provided a new strategy for the therapeutic treatment of CRC. [ABSTRACT FROM AUTHOR]

Background: Colorectal carcinoma (CRC) is the third most common cancer and second most common cause of cancer-related deaths worldwide. Ribonucleic acid (RNA) N6-methyladnosine (m6A) and methyltransferase-like 3 (METTL3) play key roles in cancer progression. However, the roles of m6A and METTL3 in CRC progression require further clarification. Methods: Adenoma and CRC samples were examined to detect m6A and METTL3 levels, and tissue microarrays were performed to evaluate the association of m6A and METTL3 levels with the survival of patients with CRC. The biological functions of METTL3 were investigated through cell counting kit-8, wound healing, and transwell assays. M6A epitranscriptomic microarray, methylated RNA immunoprecipitation-qPCR, RNA stability, luciferase reporter, and RNA immunoprecipitation assays were performed to explore the mechanism of METTL3 in CRC progression. Results: M6A and METTL3 levels were substantially elevated in CRC tissues, and patients with CRC with a high m6A or METTL3 levels exhibited shorter overall survival. METTL3 knockdown substantially inhibited the proliferation, migration, and invasion of CRC cells. An m6A epitranscriptomic microarray revealed that the cell polarity regulator Crumbs3 (CRB3) was the downstream target of METTL3. METTL3 knockdown substantially reduced the m6A level of CRB3, and inhibited the degradation of CRB3 mRNA to increase CRB3 expression. Luciferase reporter assays also showed that the transcriptional level of wild-type CRB3 significantly increased after METTL3 knockdown but not its level of variation. Knockdown of YT521-B homology domain–containing family protein 2 (YTHDF2) substantially increased CRB3 expression. RNA immunoprecipitation assays also verified the direct interaction between the YTHDF2 and CRB3 mRNA, and this direct interaction was impaired after METTL3 inhibition. In addition, CRB3 knockdown significantly promoted the proliferation, migration, and invasion of CRC cells. Mechanistically, METTL3 knockdown activated the Hippo pathway and reduced nuclear localization of Yes1-associated transcriptional regulator, and the effects were reversed by CRB3 knockdown. Conclusions: M6A and METTL3 levels were substantially elevated in CRC tissues relative to normal tissues. Patients with CRC with high m6A or METTL3 levels exhibited shorter overall survival, and METTL3 promoted CRC progression. Mechanistically, METTL3 regulated the progression of CRC by regulating the m6A–CRB3–Hippo pathway. [ABSTRACT FROM AUTHOR]

N6‐methyladenosine (m6A) methyltransferase METTL3 has been implicated in carcinogenesis, which may be associated the overexpression of MALAT1. However, the downstream mechanics actions remain largely unknown. This study intends to probe the downstream mechanism of the N6‐methyladenosine (m6A) methyltransferase METTL3 and MALAT1 in adriamycin resistance in breast cancer. Through Bioinformatics databases lncMAP, TCGA and GTEx, we predicted the downstream transcription factors E2F1 and AGR2 of MALAT1 in breast cancer. The Cancer Genome Atlas and Genotype‐Tissue Expression (GTEx) databases were used to screen the downstream target genes of MALAT1. MeRIP‐qPCR was used to detect the m6A level of MALAT1 in cells. RIP was used to detect the binding between MALAT1 and E2F1, and chromatin immunoprecipitation (ChIP) for the binding of E2F1 to AGR2 promoter. Cell Counting Kit‐8 and colony formation assays were used to detect cell viability. Transwell was used to detect cell invasion. Quantitative reverse transcription polymerase chain reaction (qRT‐PCR) and western blot were used to detect the expression of related genes and proteins. A nude mouse xenograft tumor model was established to observe the effect of METTL3 on adriamycin resistance of breast cancer. The total survival of mice after exogenous gene silencing was analyzed by the Kaplan–Meier method. METTL3 was highly expressed in adriamycin‐resistant breast cancer cells. METTL3 promotes adriamycin resistance in breast cancer cells. METTL3 mediates the expression of MALAT1 in adriamycin‐resistant breast cancer through m6A. MALAT1 increases adriamycin resistance in breast cancer cells by recruiting E2F1 to activate AGR2 transcription. METTL3 can regulate the expression of MALAT1 through m6A, mediate the E2F1/AGR2 axis, and promote the adriamycin resistance of breast cancer. METTL3 may modify MALAT1 protein through m6A, recruit E2F1 and activate downstream AGR2 expression, thus promoting adriamycin resistance in breast cancer. [ABSTRACT FROM AUTHOR]

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal human cancers with a lower 5-year survival rate. N6-methyladenosine (m6A) methylation, an important epigenetic modification, has been reported to associate with physiological and pathological processes of cancers. However, its role in ESCC remains unclear. In this work, we found that the m6A levels were elevated in ESCC cancer tissues and ESCC cells. The PPI network demonstrated that METTL3, METTL14, WTAP, RBM15, and KIAA1429 were all significantly associated with each other. Moreover, we found a significant upregulation of METTL3 mRNA and protein amounts in ESCC tissues. The METTL3 mRNA expression level of tissues had associations with ESCC differentiation extent and sex (p < 0.05). The METTL3 mRNA expression level of tissues, sensitivity for diagnosing ESCC was 75.00%, specificity was 72.06% and area under the ROC curve was 0.8030. Depletion of METTL3 markedly diminished m6A levels in human ESCC cell lines and METTL3 overexpression restored the reduction in m6A levels. These results suggested that METTL3 is the primary enzyme that modulates m6A methylation and a critical regulatory factor in ESCC. Additionally, METTL3 knockdown significantly suppressed the ESCC cell proliferation, while METTL3 overexpression markedly promoted ESCC cell proliferation both in cell and animal models. These results demonstrated that METTL3 promotes ESCC development. Furthermore, METTL3 may modulate the cell cycle of ESCC cells through a p21-dependent pattern. METTL3-guided m6A modification may contribute to the progression of ESCC via the p21-axis. Our study is the first investigation to report that METTL3-mediated m6A methylation plays a crucial role in ESCC oncogenesis and highlights that METTL3 might be a potential biomarker and therapeutic target for ESCC patients. • Increased m6A amounts were detected in about 80% of ESCC tissue and cell samples. • METTL3 mRNA and protein amounts were increased in ESCC tissue specimens in comparison with adjacent tissue samples. • METTL3 increased in the level of m6A in ESCC and induced ESCC growth both in cell and animal models. • METTL3-associated alteration of m6A level is involved in ESCC progression through p21 signaling. [ABSTRACT FROM AUTHOR]

Objective To observe the effects of methyltransferase-like 3 ( METTL3) gene on the expression levels of tumor proteins c-Myc, EGFR, and Bcl-2 in the prostate cancer cell lines PC-3 and DU145 and to investigate the mechanism. Methods We used RNA interference technology to synthesize METTL3 siRNA-1400 and negative siRNA. We divided PC-3 cells into the blank control group, negative control group, and experimental group, and also divided the DU145 cells into the blank control group, negative control group, and experimental group. The cells in the blank control group were not treated, the cells in the negative control group were transfected with negative control siRNA, and the cells in the experimental group were transfected with METL3 siRNA-1400, respectively. Western blotting was used to detect the expression of tumor proteins c-Myc, EGFR and Bcl-2 in each group. The m6A modification level of RNA in each group was detected by Dolt blotting. Results Western blotting showed that the protein levels of c-Myc, EGFR and Bcl-2 in the experimental groups were significantly lower than those in the blank control groups and negative control groups in the PC-3 and DU145 cells (all P < 0. 01). The m6A modification levels of RNA in the experimental groups were significantly lower than those in the blank control groups and negative control groups in the PC-3 and DU145 cells (all P < 0. 01). Conclusion Silencing METTL3 gene in prostate cancer PC-3 and DU145 cells inhibits the expression of c-Myc, EGFR and Bcl-2, and the underlying mechanism may be related to the involvement of METTL3 in m6A modification of RNA. [ABSTRACT FROM AUTHOR]

N6-methylated adenosine (m 6 A) is a crucial RNA modification in eukaryotes, particularly in cancer. However, its role in cervical cancer (CC) is unclear. We aimed to elucidate the part of m 6 A in CC by analyzing methyltransferase-like 3 (METTL3) expression, identifying downstream targets, and exploring the underlying mechanism. We assessed METTL3 expression in CC using western blotting, quantitative polymerase chain reaction (qPCR), and immunohistochemistry. In vitro and in vivo experiments examined METTL3's role in CC. We employed RNA sequencing, methylated RNA immunoprecipitation sequencing, qPCR, and RNA immunoprecipitation qPCR to explore METTL3's mechanism in CC. METTL3 expression was upregulated in CC, promoting cell proliferation and metastasis. METTL3 knockdown inhibited human cervical cancer by inactivating AKT/mTOR signaling pathway. METTL3-mediated m 6 A modification was observed in CC cells, targeting phosphodiesterase 3A (PDE3A). METTL3 catalyzed m 6 A modification on PDE3A mRNA through YTH domain family protein 3 (YTHDF3). Our study indicated the mechanism of m 6 A modification in CC and suggested the METTL3/YTHDF3/PDE3A axis as a potential clinical target for CC treatment., (© 2024 The Author(s). The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

Follicular cysts are a common reproductive disorder in domestic animals that cause considerable economic losses to the farming industry. Effective prevention and treatment methods are lacking because neither the pathogenesis nor formation mechanisms of follicular cysts are well-understood. In this study, we first investigated the granulosa cells (GCs) of cystic follicles isolated from pigs. We observed a significant reduction in the expression of methyltransferase-like 3 (METTL3). Subsequent experiments revealed that METTL3 downregulation in GCs caused a decrease in m 6 A modification of pri-miR-21. This reduction further inhibited DGCR8 recognition and binding to pri-miR-21, dampening the synthesis of mature miR-21-5p. Additionally, the decrease in miR-21-5p promotes IL-1β expression in GCs. Elevated IL-1β activates the NFκB pathway, in turn upregulating apoptotic genes TNFa and BAX/BCL2. The subsequent apoptosis of GCs and inhibition of autophagy causes downregulation of CYP19A1 expression. These processes lower oestrogen secretion and contribute to follicular cyst formation. In conclusion, our findings provide a foundation for understanding and further exploring the mechanisms of follicular-cyst development in farm animals. This work has important implications for treating ovarian disorders in livestock and could potentially be extended to humans., (© 2024 Wiley Periodicals LLC.)

Background: Arecoline is known as the main active carcinogen found in areca nut extract that drives the pathological progression of oral squamous cell carcinoma (OSCC). Studies have revealed that dysregulation of RNA N6-methyladenosine (m6A) methyltransferase components is intimately linked to cancer initiation and progression, including oral cancer. Methods: The arecoline-induced dysregulated methyltransferase-like 3 (METTL3) gene was identified using RNA-seq transcriptome assay. Using in vitro and in vivo models, the biological roles of METTL3 in arecoline-transformed oral cancer were examined. Results: We found that METTL3 was markedly elevated in arecoline-exposed OSCC cell lines and OSCC tissues of areca nut chewers. We identified that hypoxia-inducible factor 1-alpha (HIF-1α) stimulated METTL3 expression at the transcriptional level and further proved that METTL3-MYC-HIF-1α formed a positive autoregulation loop in arecoline-transformed OSCC cells. Subsequently, we manifested that METTL3 depletion profoundly reduced cell proliferation, cell migration, oncogenicity, and cisplatin resistance of arecoline-exposed OSCC cells. Conclusions: Developing novel strategies to target METTL3 may be a potential way to treat OSCC patients, particularly those with areca nut chewing history and receiving cisplatin treatment.