SYVN1-MTR4-MAT2A Signaling Axis Regulates Methionine Metabolism in Glioma Cells

Mechanism of CXCL8 regulation of methionine metabolism to promote angiogenesis in gliomas

BACKGROUND

Gliomas are the most common malignant brain tumors characterized by angiogenesis and invasive growth. A detailed understanding of its molecular characteristics could provide potential therapeutic targets. In the present study, we sought to explore the key gene CXCL8 in methionine metabolism in gliomas and its potential role in angiogenesis.

METHODS

U251 glioma cells were divided into control and methionine-restriction tolerant (constructed with 1/4 of the standard level of methionine in the culture medium) groups for transcriptome and metabolome analysis. To confirm the functions and mechanism of CXCL8 in glioma, heat map, volcano map, Go enrichment, gene set enrichment analysis (GSEA), protein-protein interaction network analysis, RT-PCR, western blotting assays, chicken embryo chorioallantoic membrane (CAM) test, chicken embryo yolk sac membrane (YSM) test and transplantation tumor nude mice model were performed. The TCGA database, CGGA database and clinical tissue samples were used to analyze CXCL8's significance on prognosis for patients with glioma.

RESULTS

CXCL8 expression was significantly up-regulated in methionine-restricted tolerance cells, it also activated vascular system development and triggered angiogenesis. CXCL8 expression is negatively correlated with survival prognosis in gliomas.

CONCLUSIONS

Glioma cells promote angiogenesis in methionine-restricted environments through the activation of CXCL8, compensating for nutrient deprivation, and possibly contributing to the failure of antiangiogenic therapy.

MiR-760 exerts a critical regulatory role in glioma proliferation, migration, and invasion by modulating MMP2 expression

Background: Glioma represents the predominant subtype of brain tumor, characterized by an unfavorable prognosis. Current evidence indicates the involvement of microRNAs (miRNAs) in the initiation and progression of glioma malignancies. While miR-760 has been recognized in the context of tumorigenesis, its precise role in gliomas remains insufficiently explored. Methods: In this investigation, we harnessed the GSE25631 database to scrutinize the aberrant expression profiles of microRNAs, whereby the diminished expression of miR-760 in glioblastoma was validated. Our aim was to delineate the expression patterns of microRNA-760 (miR-760) and probe its prognostic significance within the realm of glioma. Employing quantitative real-time polymerase chain reaction, we ascertained the relative expression levels of miR-760 and MMP2 in glioma cell lines. The impact of miR-760 on cell proliferation, migration, and invasion was assessed through Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and Transwell assays. Bioinformatics analysis corroborated the downstream target gene of miR-760. Furthermore, a luciferase reporter experiment was conducted to pinpoint MMP2 as the direct target gene of miR-760. The assessment of MMP2 protein levels was accomplished through Western blotting and immunofluorescence techniques. Result: Our data unequivocally revealed a substantial reduction in miR-760 expression within glioma tissues and cell lines. Heightened miR-760 levels exerted a restraining influence on the proliferation, migration, and invasion capabilities of glioma cell lines. The outcomes of our bioinformatics analysis unveiled the ability of miR-760 to engage with and curtail MMP2 expression. Collectively, these findings posit that miR-760 exerts a restraining influence on glioma growth by orchestrating the upregulation of miR-760 along the miR-760/MMP2 axis. Conclusion: The delineation of the miR-760/MMP2 axis promises to broaden our comprehension of the intricate molecular mechanisms underpinning glioma proliferation and may unveil prospective therapeutic avenues for the management of glioma.

Characterization of methionine dependence in melanoma cells

Dietary methionine restriction is associated with a reduction in tumor growth in preclinical studies and an increase in lifespan in animal models. The mechanism by which methionine restriction inhibits tumor growth while sparing normal cells is incompletely understood. We do know that normal cells can utilize methionine or homocysteine interchangeably (methionine independence) while most cancer cells are strictly dependent on methionine availability. Here, we compared a typical methionine dependent and a rare methionine independent melanoma cell line. We show that replacing methionine, a methyl donor, with its precursor homocysteine generally induced hypomethylation in gene promoters. This decrease was similar in methionine dependent and methionine independent cells. There was only a low level of pathway enrichment, suggesting that the hypomethylation is generalized rather than gene specific. Whole proteome and transcriptome were also analyzed. This analysis revealed that contrarily to the effect on methylation, the replacement of methionine with homocysteine had a much greater effect on the transcriptome and proteome of methionine dependent cells than methionine independent cells. Interestingly, methionine adenosyltransferase 2A (MAT2A), responsible for the synthesis of S-adenosylmethionine from methionine, was equally strongly upregulated in both cell lines. This suggests that the absence of methionine is equally detected but triggers different outcomes in methionine dependent versus independent cells. Our analysis reveals the importance of cell cycle control, DNA damage repair, translation, nutrient sensing, oxidative stress and immune functions in the cellular response to methionine stress in melanoma.

Arylsulfatase D is a prognostic biomarker that promotes glioma cells progression through JAK2/STAT3 pathway and M2 macrophage infiltration

Background

Arylsulfatase D (ARSD) belongs to the sulfatase family and plays a crucial role in maintaining the proper structure of bone and cartilage matrix. Although several researches have revealed the functions of ARSD in tumor progression, the prognostic value of ARSD in glioma and the related mechanisms have not been fully investigated.

Methods

We performed a pan-cancer analysis of ARSD, and investigated the relationship between expression of ARSD and overall survival (OS) in multiple glioma datasets. ROC curves and nomograms were created to investigate the predictive capacity of ARSD. Immune and analysis were conducted to investigate the mechanisms underlying the roles of ARSD in glioma. Glioma tissue samples were collected to verify the expression of ARSD in glioma, while the functions of ARSD were explored using cell experiment. M2 macrophage infiltration assay was used to determine the relation between ARSD and tumor immune microenvironment.

Results

Survival analysis indicated that individuals with high ARSD expression in glioma had a shorter survival time. Cox analysis showed that ARSD had a good ability for predicting prognosis in glioma. Immune analysis suggested that ARSD could regulate immune cell infiltration and affect the Cancer-Immunity Cycle to create an immunosuppressive environment. Combined with cell experiment and bioinformatic analysis, we found that ARSD can promote glioma progression through regulation of JAK2/STAT3 pathway and M2 macrophage infiltration.

Conclusion

Our study found that ARSD can promote glioma development by regulating immune microenvironment and JAK2/STAT3 signaling pathway, which provided a potential therapy target for glioma treatment.

Characterization of methionine dependence in melanoma cells

Dietary methionine restriction is associated with a reduction in tumor growth in preclinical studies and an increase in lifespan in animal models. The mechanism by which methionine restriction inhibits tumor growth while sparing normal cells is incompletely understood. We do know that normal cells can utilize methionine or homocysteine interchangeably (methionine independence) while most cancer cells are strictly dependent on methionine availability. Here, we compared a typical methionine dependent and a rare methionine independent melanoma cell line. We show that replacing methionine, a methyl donor, with its precursor homocysteine generally induced hypomethylation in gene promoters. This decrease was similar in methionine dependent and methionine independent cells. There was only a low level of pathway enrichment, suggesting that the hypomethylation is generalized rather than gene specific. Whole proteome and transcriptome were also analyzed. This analysis revealed that contrarily to the effect on methylation, the replacement of methionine with homocysteine had a much greater effect on the transcriptome and proteome of methionine dependent cells than methionine independent cells. Interestingly, methionine adenosyltransferase 2A (MAT2A), responsible for the synthesis of s-adenosylmethionine from methionine, was equally strongly upregulated in both cell lines. This suggests that the absence of methionine is equally detected but triggers different outcomes in methionine dependent versus independent cells. Our analysis reveals the importance of cell cycle control, DNA damage repair, translation, nutrient sensing, oxidative stress and immune functions in the cellular response to methionine stress in melanoma.

A novel prognostic related lncRNA signature associated with amino acid metabolism in glioma

Background

Glioma is one of the deadliest malignant brain tumors in adults, which is highly invasive and has a poor prognosis, and long non-coding RNAs (lncRNAs) have key roles in the progression of glioma. Amino acid metabolism reprogramming is an emerging hallmark in cancer. However, the diverse amino acid metabolism programs and prognostic value remain unclear during glioma progression. Thus, we aim to find potential amino-related prognostic glioma hub genes, elaborate and verify their functions, and explore further their impact on glioma.

Methods

Glioblastoma (GBM) and low-grade glioma (LGG) patients' data were downloaded from TCGA and CCGA datasets. LncRNAs associated with amino acid metabolism were discriminated against via correlation analysis. LASSO analysis and Cox regression analysis were conducted to identify lncRNAs related to prognosis. GSVA and GSEA were performed to predict the potential biological functions of lncRNA. Somatic mutation data and CNV data were further built to demonstrate genomic alterations and the correlation between risk scores. Human glioma cell lines U251 and U87-MG were used for further validation in vitro experiments.

Results

There were eight amino-related lncRNAs in total with a high prognostic value that were identified via Cox regression and LASSO regression analyses. The high risk-score group presented a significantly poorer prognosis compared with the low risk-score group, with more clinicopathological features and characteristic genomic aberrations. Our results provided new insights into biological functions in the above signature lncRNAs, which participate in the amino acid metabolism of glioma. LINC01561 is one of the eight identified lncRNAs, which was adopted for further verification. In in vitro experiments, siRNA-mediated LINC01561 silencing suppresses glioma cells' viability, migration, and proliferation.

Conclusion

Novel amino-related lncRNAs associated with the survival of glioma patients were identified, and a lncRNA signature can predict glioma prognosis and therapy response, which possibly has vital roles in glioma. Meanwhile, it emphasized the importance of amino acid metabolism in glioma, particularly in providing deeper research at the molecular level.

Overview of Methionine Adenosyltransferase 2A (MAT2A) as an Anticancer Target: Structure, Function, and Inhibitors

Methionine adenosyltransferase 2A (MAT2A) is a rate-limiting enzyme in the methionine cycle that primarily catalyzes the synthesis of S-adenosylmethionine (SAM) from methionine and adenosine triphosphate (ATP). MAT2A has been recognized as a therapeutic target for the treatment of cancers. Recently, a few MAT2A inhibitors have been reported, and three entered clinical trials to treat solid tumorsor lymphoma with MTAP loss. This review aims to summarize the current understanding of the roles of MAT2A in cancer and the discovery of MAT2A inhibitors. Furthermore, a perspective on the use of MAT2A inhibitors for the treatment of cancer is also discussed. We hope to provide guidance for future drug design and optimization via analysis of the binding modes of known MAT2A inhibitors.

Adipocytic Glutamine Synthetase Upregulation via Altered Histone Methylation Promotes 5FU Chemoresistance in Peritoneal Carcinomatosis of Colorectal Cancer

The development of resistance to 5-fluorouracil (5FU) chemotherapy is a major handicap for sustained effective treatment in peritoneal carcinomatosis (PC) of colorectal cancer (CRC). Metabolic reprogramming of adipocytes, a component of the tumor microenvironment and the main composition of peritoneum, plays a significant role in drug resistance of PC, with the mechanisms being not fully understood. By performing metabolomics analysis, we identified glutamine (Gln), an important amino acid, inducing resistance to 5FU-triggered tumor suppression of CRC-PC through activating mTOR pathway. Noteworthily, genetic overexpression of glutamine synthetase (GS) in adipocytes increased chemoresistance to 5FU in vitro and in vivo while this effect was reversed by pharmacological blockage of GS. Next, we showed that methionine metabolism were enhanced in amino acid omitted from CRC-PC of GS transgenic (Tg^GS) mice, increasing intracellular levels of S-carboxymethy-L-cys. Moreover, loss of dimethylation at lysine 4 of histone H3 (H3k4me2) was found in adipocytes in vitro, which may lead to increased expression of GS. Furthermore, biochemical inhibition of lysine specific demethylase 1 (LSD1) restored H3k4me2, thereby reducing GS-induced chemoresistance to 5FU. Our findings indicate that GS upregulation-induced excessive of Gln in adipocytes via altered histone methylation is potential mediator of resistance to 5FU chemotherapy in patients with CRC-PC.