METTL3-mediated m6A modification of pri-miR-148a-3p affects prostate cancer progression by regulating TXNIP.

Prostate cancer (PCa) severely affects men's health worldwide. The mechanism of methyltransferase-like 3 (METTL3) in affecting PCa development by regulating miR-148a-3p expression via N6-methyladenosine (m6A) modification was investigated. METTL3, miR-148a-3p, and thioredoxin interacting protein (TXNIP) levels were determined using RT-qPCR and Western blotting. The m6A modification level of miR-148a-3p was observed by Me-RIP assay. Bioinformatics website predicted miR-148a-3p and TXNIP levels in PCa and their correlation, and the binding site between them was verified by dual-luciferase assay. The proliferation, migration, invasion, and apoptosis of PCa cells were examined by CCK-8 assay, Transwell assay, and flow cytometry. A transplanted tumor model was established in nude mice to observe the tumor growth ability, followed by determination of TXNIP levels in tumor tissues by immunohistochemistry. METTL3 interference restrained the proliferation, migration, and invasion and promoted apoptosis of PCa cells. METTL3 up-regulated miR-148a-3p by promoting the m6A modification of pri-miR-148a-3p in PCa cells. miR-148a-3p overexpression nullified the inhibitory actions of silencing METTL3 on PCa cell growth. miR-148a-3p facilitated PCa cell growth by silencing TXNIP. METTL3 interference inhibited tumor growth by down-regulating miR-148a-3p and up-regulating TXNIP. METTL3 promoted miR-148a-3p by mediating the m6A modification of pri-miR-148a-3p, thereby targeting TXNIP, interfering with METTL3 to inhibit the proliferation, migration and invasion of PCa cells, promote apoptosis, and inhibit tumor growth in nude mice.

Li G ，Liu J ，Wang Y ，Liu H ，Fu J ，Zhao Y ，Huang Y ... -  《-》

METTL3/IGF2BP1 promotes the development of triple-negative breast cancer by mediating m6A methylation modification of PRMT7.

PRMT7 is upregulated in breast cancer and promotes tumor metastasis. Here we aimed to explore the function and mechanism of PRMT7 in triple-negative breast cancer (TNBC). The expression of PRMT7, METTL3 and IGF2BP1 was detected by immunohistochemistry (IHC), qRT-PCR and western blot. Cell viability and proliferation were measured using MTT and EdU assay. Flow cytometry and TUNEL assays were used to evaluate apoptosis. Invasion and migration were assessed by transwell and wound healing assays, respectively. Glucose consumption and lactate production were measured to assess glycolysis. In addition, the interaction between METTL3 and PRMT was verified by methylated RNA immunoprecipitation. The roles of METTL3 and PRMT in vivo were investigated through a xenograft model. PRMT7 was upregulated in TNBC tissues and cells, and the knockdown of PRMT7 inhibited cell proliferation, invasion, migration and glycolysis, but induced apoptosis in TNBC cells. METTL3/IGF2BP1 enhanced PRMT7 expression by mediating the m6A methylation modification of PRMT7. Besides, METTL3 knockdown suppressed the progression of TNBC cells and regulated the WNT/β-catenin pathway via PRMT7. Moreover, silencing METTL3 restrained TNBC tumor growth in vivo through regulating PRMT7. METTL3/IGF2BP1 facilitates the progression of TNBC by mediating m6A methylation modification of PRMT7.

Lu W ，Yang S 《-》

Mechanism of METTL3 in the proliferation, invasion, and migration of intrahepatic cholangiocarcinoma cells via m6A modification.

Intrahepatic cholangiocarcinoma (ICC) is a primary invasive malignant tumor. This study was conducted to explore the role of methyltransferase-like 3 (METTL3)-mediated m6A modification in ICC cells and provide novel targets for ICC treatment. Levels of METTL3/YTH N6-methyladenosine RNA binding protein 2 (YTHDF2)/Nedd4 family interacting protein 1 (NDFIP1) in cells were determined. Cell viability, proliferation, invasion, and migration were evaluated. The enrichments of METTL3, YTHDF2, and m6A on NDFIP1 mRNA were analyzed. The mRNA stability was determined. Inhibition of YTHDF2 or NDFIP1 was combined with si-METTL3 to confirm the mechanism. The role of METTL3 in vivo was verified. METTL3 was overexpressed in ICC cells. METTL3 silencing suppressed ICC cell malignant behaviors, which were reversed by METTL3 overexpression. METTL3 increased m6A modification on NDFIP1 mRNA, facilitated YTHDF2 recognition of m6A, and promoted NDFIP1 mRNA degradation, thereby suppressing NDFIP1 expression. YTHDF2 inhibition increased NDFIP1 mRNA levels. NDFIP1 downregulation partially reversed the inhibitory effects of si-METTL3 on ICC cell behaviors, while NDFIP1 overexpression partially reversed the promotive effects of METTL3 on ICC cell behaviors. METTL3 downregulation suppressed ICC growth by increasing NDFIP1 expression. In conclusion, METTL3 aggravates ICC cell proliferation, invasion, and migration by promoting the degradation of NDFIP1 mRNA in a YTHDF2-dependent manner.

Jiang X ，Tan H 《-》

The role of METTL3-mediated CircStk4 modification in the treatment of chronic glomerulonephritis with Qi Teng Xiao Zhuo granule.

Qi Teng Xiao Zhuo granule (QTXZG), a compound preparation used in traditional Chinese medicine, is a highly effective treatment for chronic glomerulonephritis (CGN). Previously, the mechanism of circStk4 and the N6-methyladenosine (m6A) modification of circStk4 in CGN was elucidated in vivo. Nevertheless, there hasn't been any research done on the connection between circStk4 and QTXZG's mechanism in CGN treatment. The current study intended to clarify the molecular mechanism of QTXZG in CGN therapy by both in vitro and in vivo investigations. Mouse mesangial cells (MMCs) were used to measure the rate of proliferation and apoptosis using flow cytometry and the Cell Counting Kit-8 (CCK-8) assay. The expression of markers associated with proliferation, apoptosis, and autophagy was analysed using reverse transcription quantitative PCR (RT-qPCR), western blotting (WB), and immunofluorescence (IF), respectively. Methylated RNA immunoprecipitation-qPCR (MeRIP-qPCR) was utilized to analyse the m6A modification of circStk4, and METTL3 expression was assessed using RT-qPCR. Subsequently, miR-133a-3p and C1 expression was examined using RT-qPCR, WB, and IF. Adeno-associated virus 9 (AAV9)-circStk4 knockdown vector and a METTL3 inhibitor were used to explore the roles of METTL3 and circStk4 in CGN. Additionally, molecular docking and cellular thermal shift assays (CETSAs) were performed to assess the binding affinity between METTL3 and the active compounds in QTXZG. Mechanistically, QTXZG reduced METTL3 expression and decreased circStk4 m6A levels while decreasing circStk4 levels and regulating the miR-133a-3p/C1 axis. Functionally, QTXZG inhibited MMCs and renal tissue proliferation, promoted apoptosis and autophagy, and reduced inflammation. In vivo experiments further confirmed that downregulated ircStk4 and METTL3 expression were accompanied by the therapeutic effects of QTXZG, resulting in a significant attenuation of renal injury, reduction in inflammation, inhibition of renal tissue proliferation and promotion of apoptosis and autophagy. The present study revealed that QTXZG reduced circStk4 m6A and METTL3 expression to regulate the circStk4/miR-133a-3p/C1 axis in the treatment of CGN and thus inhibited glomerular tissue/membrane cell proliferation and promoted autophagy and apoptosis; these results uncovered a new mechanism by which QTXZG reduced CGN and imply that METTL3 might be a target for innovative therapeutic approaches.

Qin X ，Chen H ，Zheng W ，Hu W ，Xu X ，Gao J ... -  《-》

METTL3-mediated SMPDL3A promotes cell growth, metastasis and immune process of hepatocellular carcinoma by regulating LRPPRC.

Methyltransferase-like protein 3 (METTL3) has been confirmed to act as a tumor promoter to regulate hepatocellular carcinoma (HCC) progression. Therefore, more roles and mechanisms of METTL3 in HCC progression deserve to be further revealed. The mRNA and protein levels of METTL3, sphingomyelin phodiesterase acid-like 3 A (SMPDL3A), and leucine rich pentatricopeptide repeat containing (LRPPRC) were determined by qRT-PCR and western blot. Cell proliferation, apoptosis, invasion and migration were detected by CCK8 assay, EdU assay, flow cytometry, transwell assay and wound healing assay. HCC cells were co-cultured with phytohemagglutinin-stimulated peripheral blood mononuclear cells, cytokine-induced killer cells, or CD8 + T-cells. IFN-γ, TNF-α levels, HCC cell survival rate and CD8 + T-cell apoptosis were determined to assess cell immune process. The interaction between METTL3, SMPDL3A and LRPPRC was assessed by MeRIP assay, RIP assay, dual-luciferase reporter assay or Co-IP assay. Animal experiments were performed to evaluate the effect of METTL3 knockdown on HCC tumorigenesis and lung metastasis. METTL3 was upregulated in HCC tissues and cells, and its knockdown repressed HCC cell proliferation, invasion, migration, immune process and promoted apoptosis. METTL3 increased SMPDL3A mRNA stability by m6A methylation modification, and this modification could be recognized by IGF2BP1. SMPDL3A overexpression reversed the inhibitory effect of METTL3 knockdown on HCC cell growth, metastasis and immune process. SMPDL3A interacted with LRPPRC to positively regulate its expression, and LRPPRC overexpression also eliminated the regulation of SMPDL3A silencing on HCC progression. In addition, downregulation of METTL3 repressed HCC tumorigenesis and lung metastasis via mediating SMPDL3A/LRPPRC axis. METTL3 accelerated HCC cell growth, metastasis and immune process by regulating SMPDL3A/LRPPRC axis, providing a potential target for HCC treatment.

Xu W ，Tao M ，Liu Y ，Yan J ，Hu J ，Wang L ... -  《-》