Knockdown of MTHFD2 inhibits proliferation and migration of nasopharyngeal carcinoma cells through the ERK signaling pathway

MTHFD2: A significant mitochondrial metabolic enzyme and a novel target for anticancer therapy

Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) is a crucial mitochondrial enzyme that operates within the folate one-carbon metabolic pathway. In recent years, it has been discovered that its expression is upregulated in numerous tumors and is correlated with the onset and progression of tumors, as well as poor prognosis. In contrast to its isoenzymes, it is overexpressed in tumors and is either expressed at low levels or not expressed at all in normal tissues. Consequently, it has received extensive attention and has been proposed as a novel anticancer target. In this paper, we review the functions of MTHFD2 in tumors, its regulatory mechanisms, and research progress on MTHFD2 inhibitors. Additionally, we provide insights into future research directions and the design and development of inhibitors for MTHFD2.

MTHFD2 promotes esophageal squamous cell carcinoma progression via m6A modification‑mediated upregulation and modulation of the PEBP1‑RAF1 interaction

One‑carbon metabolism plays an important role in cancer progression. Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2), a mitochondrial enzyme in one‑carbon metabolism, is dysregulated in several cancer types. However, the precise role and mechanisms of MTHFD2 in esophageal squamous cell carcinoma (ESCC) remain unclear. The present study unravels the multifaceted mechanisms by which MTHFD2 contributes to ESCC pathogenesis. Bioinformatics analyses revealed significant upregulation of MTHFD2 in ESCC tumor tissues, which was associated with advanced disease stage and poor patient prognosis. Validating these findings in clinical samples, MTHFD2 overexpression was confirmed through immunohistochemistry, Reverse transcription‑quantitative PCR and western blotting. Knockdown of MTHFD2 inhibited ESCC cell viability, colony formation, invasion, and tumor growth in vivo, indicating its oncogenic potential. Mechanistically, the present study elucidated a novel regulatory axis involving N6‑methyladenosine modification and MTHFD2 mRNA stability. Specifically, methyltransferase‑like 3 (METTL3) and insulin‑like growth factor 2 mRNA binding protein 2 (IGF2BP2) were identified as key mediators of m6A‑dependent stabilization of MTHFD2 mRNA, contributing to its elevated expression in ESCC. Furthermore, MTHFD2 was found to activate PI3K/AKT and ERK signaling pathways by modulating interaction between phosphatidylethanolamine‑binding protein 1 (PEBP1) and raf‑1 proto‑oncogene (RAF1). This modulation was achieved through direct binding of MTHFD2 to PEBP1, disrupting the inhibitory effect of PEBP1 on RAF1 and promoting downstream pathway activation. The oncogenic functions of MTHFD2 were attenuated upon PEBP1 knockdown, underscoring the role of the MTHFD2‑PEBP1 axis in ESCC progression. In summary, the present study uncovers a novel regulatory mechanism involving m6A modification and the MTHFD2‑PEBP1 axis, unveiling potential therapeutic avenues for targeting MTHFD2 in ESCC.

MTHFD2 marks pemetrexed resistance in pulmonary adenocarcinoma with EGFR wild type

PURPOSE

Lung cancer is the leading cause of cancer-related deaths worldwide. Patients with an amplification of the MTHFD2 gene have a particularly poor prognosis. MTHFD2 signaling has been associated with migration, metastasis, and proliferation of lung cancer cells mediated through ERK signaling. Although the enzymatic activity of the MTHFD2 protein is well understood, little is known about its larger role in chemoresistance.

METHODS

Seventy-nine of non-small cell lung cancer (NSCLC) samples with clinical follow-up were subjected to immunohistochemical staining for MTHFD2 and sequenced using next generation sequencing (NGS) to determine EGFR status. MTHFD2 gene was knocked down in two NSCLC cell lines with wild type EGFR gene (HCC44 and H1993) where MTHFD2 signaling and chemotherapy resistance against pemetrexed were evaluated.

RESULTS

MTHFD2 expression data revealed a strong prognosis relevance in adenocarcinoma (LUAD). Immunoblotting of cell lines showed a MTHFD2 dependent and cell type specific ERK signaling in EGFR wild type cells. MTHFD2 expression induced proliferation of NSCLC cells and their resistance against pemetrexed. Knocking down the MTHFD2 gene induced cycle arrest, however, it did not activate apoptosis signaling within HCC44 cell line.

CONCLUSIONS

MTHFD2 expression is strongly associated with prognosis in LUAD patients, as well as with increased cellular proliferation and resistance to pemetrexed in LUAD patients with wild-type EGFR. These findings suggest that MTHFD2 could serve as a valuable biomarker for predicting treatment outcomes in LUAD. Further studies are needed to fully explore the clinical implications and potential combination therapies targeting MTHFD2 in LUAD.

MTHFD2: A metabolic checkpoint altering trophoblast invasion and migration by remodeling folate-nucleotide metabolism in recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) affects female reproduction worldwide, yet its pathological mechanisms are still unclear. It has been reported that cellular metabolism reprogramming is a critical step for trophoblasts during embryo implantation. Herein, MTHFD2 was recognized as a key metabolic checkpoint attributed to RSA occurrence. This work figured out that the expression level of MTHFD2 was significantly inhibited in villus tissues from RSA patients, suggesting the potential role of MTHFD2 in RSA occurrence. Moreover, MTHFD2 knockdown impaired cellular folate-nucleotide metabolism, induced the accumulation of AICAR, and thereby impairing the EMT process to inhibit the invasion and migration of trophoblasts Besides, the AICAR accumulation further activated the downstream AMPK which deactivated the JAK/STAT/Slug pathway and ultimately deactivated the EMT process. Using a mouse model, MTHFD2 inhibition was observed to induce embryo implantation failure in vivo. Our results highlighted MTHFD2 as a metabolic checkpoint that remodeled folate-nucleotide metabolism to regulate the EMT process and ultimately altered the migration and invasion of trophoblasts in RSA occurrence. Our findings suggested that MTHFD2 was a promising therapeutic target in recurrent spontaneous abortion treatment.

CAPRIN1/TYMS/MTHFD2 axis promotes EMT process in nasopharyngeal carcinoma development

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a type of malignant tumor occurring in the nasopharynx. It frequently leads to treatment failure after metastasis, often resulting from epithelial-mesenchymal transition (EMT). Thymidylate synthetase (TYMS) is a key enzyme involved in DNA synthesis and replication. Currently, the role of TYMS and its mechanism of upstream and downstream in EMT of NPC is unclear.

METHODS

NPC cell lines HK-1 and C666-1 were used in this study. Lentivirus carrying TYMS knockdown and overexpressed plasmids were used to regulate TYMS expression. Cell migration and invasion were examined using the wound-healing and Transwell assays, respectively. C666-1 cells were injected into the axilla and tail vein of mice to form subcutaneous tumors and construct lung metastasis model, respectively. RNA immunoprecipitation assay was used to examine the interaction between protein and mRNA. RNA-seq was performed to explore the downstream regulatory mechanism of TYMS.

RESULTS

TYMS was highly expressed in NPC tissues. TYMS silencing and upregulation inhibited and promoted EMT processes in NPC cells, respectively, as demonstrated by the expression of EMT-related proteins, including E-cadherin, Slug, MMP2, and MMP9. Cytoplasmic activation/proliferation-associated protein-1 (CAPRIN1), a protein bound with TYMS mRNA, promoted the EMT process in NPC cells. Meanwhile, TYMS knockdown reversed the effect of CAPRIN1 overexpression. Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) was down-regulated following TYMS silencing. MTHFD2 knockdown abolished the effect of TYMS overexpression.

CONCLUSION

CAPRIN1/TYMS/MTHFD2 axis drives the EMT process and thus promotes NPC development, which is a promising target in therapy and adjuvant therapy of NPC.

EP300-mediated H3 acetylation elevates MTHFD2 expression to reduce mitochondrial dysfunction in lipopolysaccharide-induced tubular epithelial cells

Sepsis represents an organ dysfunction resulting from the host's maladjusted response to infection, and can give rise to acute kidney injury (AKI), which significantly increase the morbidity and mortality of septic patients. This study strived for identifying a novel therapeutic strategy for patients with sepsis-induced AKI (SI-AKI). Rat tubular epithelial NRK-52E cells were subjected to lipopolysaccharide (LPS) exposure for induction of in-vitro SI-AKI. The expressions of E1A binding protein p300 (EP300) and methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) in NRK-52E cells were assessed by western blot and qRT-PCR, and their interaction was explored by chromatin immunoprecipitation performed with antibody for H3K27 acetylation (H3K27ac). The effect of them on SI-AKI-associated mitochondrial dysfunction of tubular epithelial cells was investigated using transfection, MTT assay, TUNEL staining, 2',7'-Dichlorodihydrofluorescein diacetate probe assay, Mitosox assay, and JC-1 staining. MTHFD2 and EP300 were upregulated by LPS exposure in NRK-52E cells. LPS increased the acetylation of H3 histone in the MTHFD2 promoter region, and EP300 suppressed the effect of LPS. EP300 ablation inhibited the expression of MTHFD2. MTHFD2 overexpression antagonized LPS-induced viability reduction, apoptosis promotion, reactive oxygen species overproduction, and mitochondrial membrane potential collapse of NRK-52E cells. By contrast, MTHFD2 knockdown and EP300 ablation brought about opposite consequences. Furthermore, MTHFD2 overexpress and EP300 ablation counteracted each other's effect in LPS-exposed NRK-52E cells. EP300-mediated H3 acetylation elevates MTHFD2 expression to reduce mitochondrial dysfunction of tubular epithelial cells in SI-AKI.

Interference with MTHFD2 induces ferroptosis in ovarian cancer cells through ERK signaling to suppress tumor malignant progression

Ovarian cancer (OC) is a deadliest gynecological cancer with the highest mortality rate. Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2), a crucial tumor-promoting factor, is over-expressed in several malignancies including OC. The present study aimed to explore the role and mechanisms of MTHFD2 in OC malignant progression. Thus, cell proliferation, cycling, apoptosis, migration, and invasion were evaluated by CCK-8 assay, EdU assay, flow cytometry, wound healing, transwell assay and western blotting. Additionally, glycolysis was assessed by measuring the level of glucose and lactate production, as well as the expressions of GLUT1, HK2 and PKM2. Then the expression of ferroptosis-related proteins and ERK signaling was detected using western blotting. Ferroptosis was detected through the measurement of iron level, GSH, MDA and ROS activities. The results revealed that MTHFD2 was highly expressed in OC cells. Besides, interference with MTHFD2 induced ferroptosis, promoted ROS accumulation, destroyed mitochondrial function, reduced ATP content and inhibited glycolysis in OC cells. Subsequently, we further found that interference with MTHFD2 affected mitochondrial function and glycolysis in OC cells through ERK signaling. Moreover, interference with MTHFD2 affected ferroptosis to inhibit the malignant progression of OC cells. Collectively, our present study disclosed that interference with MTHFD2 induced ferroptosis in OC to inhibit tumor malignant progression through regulating ERK signaling.

Overexpression of HSPB6 inhibits osteosarcoma progress through the ERK signaling pathway

Heat shock protein B6 (HSPB6) plays a certain role in the formation of several cancers, whereas its effect on osteosarcoma remains unclear. In this study, the effect of HSPB6 on osteosarcoma was validated through numerous experiments. HSPB6 was down-regulated in osteosarcoma. As indicated by the result of CCK-8 and colony formation assays, HSPB6 overexpression was likely to inhibit the osteosarcoma cells proliferation, whereas the flow cytometry analysis suggested that apoptosis of osteosarcoma cells was increased after HSPB6 overexpression. Furthermore, transwell and wound healing assays suggested that when HSPB6 was overexpressed, osteosarcoma cells migration and invasion were declined. Moreover, the western blotting assay suggested that the protein level of p-ERK1/2 was down-regulated in osteosarcoma when HSPB6 was overexpressed. Besides, the effect of HSPB6 on osteosarcoma in vivo was examined. As indicated by the result, HSPB6 overexpression was likely to prevent osteosarcoma growth and lung metastasis in vivo. As revealed by the findings of this study, HSPB6 overexpression exerted anticancer effects in osteosarcoma through the ERK signaling pathway and HSPB6 may be suitable target for osteosarcoma molecular therapies.

Intermittent Hypoxia Promotes TAM-Induced Glycolysis in Laryngeal Cancer Cells via Regulation of HK1 Expression through Activation of ZBTB10

Obstructive sleep apnea (OSA), characterized by intermittent hypoxia (IH), may increase the risk of cancer development and a poor cancer prognosis. TAMs of the M2 phenotype, together with the intermittent hypoxic environment within the tumor, drive tumor aggressiveness. However, the mechanism of TAMs in IH remains unclear. In our study, IH induced the recruitment of macrophages, and IH-induced M2-like TAMs promoted glycolysis in laryngeal cancer cells through hexokinase 1. The hexokinase inhibitor 2-deoxy-D-glucose and HK1 shRNA were applied to verify this finding, confirming that M2-like TAMs enhanced glycolysis in laryngeal cancer cells through HK1 under intermittent hypoxic conditions. Comprehensive RNA-seq analysis disclosed a marked elevation in the expression levels of the transcription factor ZBTB10, while evaluation of a laryngeal cancer patient tissue microarray demonstrated a positive correlation between ZBTB10 and HK1 expression in laryngeal carcinoma. Knockdown of ZBTB10 decreased HK1 expression, and overexpression of ZBTB10 increased HK1 expression in both laryngeal cancer cells and 293T cells. The luciferase reporter assay and Chromatin immunoprecipitation assay confirmed that ZBTB10 directly bound to the promoter region of HK1 and regulated the transcriptional activity of HK1. Finally, the CLEC3B level of the M2 supernatant is significantly higher in the IH group and showed a protumor effect on Hep2 cells. As ZBTB10-mediated regulation of HK1 affects glycolysis in laryngeal cancer, our findings may provide new potential therapeutic targets for laryngeal cancer.

Identification of microRNA editing sites in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is a malignant tumor originating from the renal tubular epithelium. Although the microRNAs (miRNAs) transcriptome of ccRCC has been extensively studied, the role of miRNAs editing in ccRCC is largely unknown. By analyzing small RNA sequencing profiles of renal tissues of 154 ccRCC patients and 22 normal controls, we identified 1025 miRNA editing sites from 246 pre-miRNAs. There were 122 editing events with significantly different editing levels in ccRCC compared to normal samples, which include two A-to-I editing events in the seed regions of hsa-mir-376a-3p and hsa-mir-376c-3p, respectively, and one C-to-U editing event in the seed region of hsa-mir-29c-3p. After comparing the targets of the original and edited miRNAs, we found that hsa-mir-376a-1_49g, hsa-mir-376c_48g and hsa-mir-29c_59u had many new targets, respectively. Many of these new targets were deregulated in ccRCC, which might be related to the different editing levels of hsa-mir-376a-3p, hsa-mir-376c-3p, hsa-mir-29c-3p in ccRCC compared to normal controls. Our study sheds new light on miRNA editing events and their potential biological functions in ccRCC.

Application of Chiral Piperidine Scaffolds in Drug Design

Chiral piperidine scaffolds are prevalent as the common cores of a large number of active pharmaceuticals in medical chemistry. This review outlined the diversity of chiral piperidine scaffolds in recently approved drugs, and also covers the scaffolds in leads and drug candidates. The significance of chiral piperidine scaffolds in drug design is also discussed in this article. With the introduction of chiral piperidine scaffolds into small molecules, the exploration of drug-like molecules can be benefitted from the following aspect: (1) modulating the physicochemical properties; (2) enhancing the biological activities and selectivity; (3) improving pharmacokinetic properties; and (4) reducing the cardiac hERG toxicity. Given above, chiral piperidine-based discovery of small molecules will be a promising strategy to enrich our molecules' library to fight against diseases.