KLF10/CBS increases the sensitivity of gastric carcinoma cells to methionine restriction by promoting sulfur transfer pathway.

Gastric cancer metastasis is a major cause of poor prognosis. Our previous research showed that methionine restriction (MR) lowers the invasiveness and motility of gastric carcinoma. In this study, we investigated the particular mechanisms of MR on gastric carcinoma metastasis. In vitro, gastric carcinoma cells (AGS, SNU-5, MKN7, KATO III, SNU-1, and MKN45) were grown in an MR medium for 24 h. In vivo, BALB/c mice were given a methionine-free (Met-) diet. Transwell assays were used to investigate cell invasion and migration. The amounts of Krüppel like factor 10 (KLF10) and cystathionine ß-synthase (CBS) were determined using quantitative real-time PCR and Western blot. To determine the relationship between KLF10 and CBS, chromatin immunoprecipitation and a dual-luciferase reporter experiment were used. Hematoxylin-eosin staining was used to detect lung metastasis. Liquid chromatography-mass spectrometry was used to determine cystathionine content. MR therapy had varying effects on the invasion and migration of gastric carcinoma cells AGS, SNU-5, MKN7, KATO III, SNU-1, and MKN45. KLF10 was highly expressed in AGS cells but poorly expressed in KATO III cells. KLF10 improved MR's ability to prevent gastric carcinoma cell invasion and migration. In addition, KLF10 may interact with CBS, facilitating transcription. Further detection revealed that inhibiting the KLF10/CBS-mediated trans-sulfur pathway lowered Met-'s inhibitory effect on lung metastasis development. KLF10 transcription activated CBS, accelerated the trans-sulfur pathway, and increased gastric carcinoma cells' susceptibility to MR.

Methionine restriction of glioma does not induce MGMT and greatly improves temozolomide efficacy in an orthotopic nude-mouse model: A potential curable approach to a clinically-incurable disease.

Glioma is a highly recalcitrant disease with a 5-year survival of 6.8 %. Temozolomide (TMZ), first-line therapy for glioma, is more effective in O6-methylguanine-DNA methyltransferase (MGMT)-negative gliomas than in MGMT-positive gliomas as MGMT confers resistance to TMZ. Methionine restriction is effective for many cancers in mouse models including glioma. The concern is that methionine restriction could induce MGMT by decreasing DNA methylation and confer resistance to TMZ. In the present study, we investigated the efficacy of combining methionine restriction with TMZ for the treatment of MGMT-negative glioma, and whether methionine restriction induced MGMT. Human MGMT-negative U87 glioma cells were used to determine the efficacy of TMZ combined with methionine restriction. Recombinant methioninase (rMETase) inhibited U87 glioma growth without induction of MGMT in vitro. The combination of rMETase and TMZ inhibited U87 cell proliferation more than either agent alone in vitro. In the orthotopic nude-mouse model, the combination of TMZ and a methionine-deficient diet was much more effective than TMZ alone: two mice out of five were cured of glioma by the combination. No mice died during the treatment period. Methionine restriction enhanced the efficacy of TMZ in MGMT-negative glioma without inducing MGMT, demonstrating potential clinical promise for improved outcome of a currently incurable disease.

Methionine restriction attenuates the migration and invasion of gastric cancer cells by inhibiting nuclear p65 translocation through TRIM47.

The prevention and treatment of gastric cancer has been the focus and difficulty of medical research. We aimed to explore the mechanism of inhibiting migration and invasion of gastric cancer cells by methionine restriction (MR). The human gastric cancer cell lines AGS and MKN45 cultured with complete medium (CM) or medium without methionine were used for in vitro experiments. MKN45 cells were injected tail vein into BALB/c nude mice and then fed with normal diet or methionine diet for in vivo experiments. MR treatment decreased cell migration and invasion, increased E-cadherin expression, decreased N-cadherin and p-p65 expressions, and inhibited nuclear p65 translocation of AGS and MKN45 cells when compared with CM group. MR treatment increased IκBα protein expression and protein stability, and decreased IκBα protein ubiquitination level and TRIM47 expression. TRIM47 interacted with IκBα protein, and overexpression of TRIM47 reversed the regulatory effects of MR. TRIM47 promoted lung metastasis formation and partially attenuated the effect of MR on metastasis formation in vivo compared to normal diet group mice. MR reduces TRIM47 expression, leads to the degradation of IκBα, and then inhibits the translocation of nuclear p65 and the migration and invasion of gastric cancer cells.

Dietary sulfur amino acid restriction in humans with overweight and obesity: a translational randomized controlled trial.

BACKGROUND: Dietary sulfur amino acid restriction (SAAR) improves metabolic health in animals. In this study, we investigated the effect of dietary SAAR on body weight, body composition, resting metabolic rate, gene expression profiles in white adipose tissue (WAT), and an extensive blood biomarker profile in humans with overweight or obesity. METHODS: N = 59 participants with overweight or obesity (73% women) were randomized stratified by sex to an 8-week plant-based dietary intervention low (~ 2 g/day, SAAR) or high (~ 5.6 g/day, control group) in sulfur amino acids. The diets were provided in full to the participants, and both investigators and participants were blinded to the intervention. Outcome analyses were performed using linear mixed model regression adjusted for baseline values of the outcome and sex. RESULTS: SAAR led to a ~ 20% greater weight loss compared to controls (ß 95% CI - 1.14 (- 2.04, - 0.25) kg, p = 0.013). Despite greater weight loss, resting metabolic rate remained similar between groups. Furthermore, SAAR decreased serum leptin, and increased ketone bodies compared to controls. In WAT, 20 genes were upregulated whereas 24 genes were downregulated (FDR < 5%) in the SAAR group compared to controls. Generally applicable gene set enrichment analyses revealed that processes associated with ribosomes were upregulated, whereas processes related to structural components were downregulated. CONCLUSION: Our study shows that SAAR leads to greater weight loss, decreased leptin and increased ketone bodies compared to controls. Further research on SAAR is needed to investigate the therapeutic potential for metabolic conditions in humans. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT04701346, registered Jan 8th 2021, https://www. CLINICALTRIALS: gov/study/NCT04701346.

Upregulation of E-cadherin by the combination of methionine restriction and HDAC2 intervention for inhibiting gastric carcinoma metastasis.

Invasion and metastasis are the leading causes of death in individuals with malignant tumors, including gastric cancer. In this study, we aim to explore the effect and related mechanisms of methionine restriction (MR) on gastric carcinoma metastasis. In the MR cell model, gastric carcinoma cells are cultured in the MR medium, and in the animal model, BALB/c nude rodents are administered with a methionine-free diet after receiving injections of MKN45 cells into the caudal vein. Transwell assay is used to detect cell invasion and migration. Chromatin immunoprecipitation is performed to investigate the levels of H3K9me2, H3K27Ac, and H3K27me3 in the E-cadherin promoter. The results show that MR inhibits gastric carcinoma cell migration, invasion, and lung metastasis. MR increases E-cadherin while reducing the H3K27me3 level in the E-cadherin promoter. E-cadherin expression in gastric carcinoma cells is adversely regulated by HDAC2. Overexpressing HDAC2 reduces the H3K27Ac level in the E-cadherin promoter, while interfering with HDAC2 increases the H3K27Ac level. HDAC2 interference under MR conditions further upregulates E-cadherin expression and inhibits gastric carcinoma cell migration, invasion, and lung metastasis. MR combined with HDAC2 interference promotes E-cadherin expression by mediating the methylation and acetylation of E-cadherin, thus inhibiting the invasion, migration, and lung metastasis of gastric carcinoma cells. Our study provides a new theoretical basis for the inhibitory effect of MR on gastric cancer.

A genetic model of methionine restriction extends Drosophila health- and lifespan.

Loss of metabolic homeostasis is a hallmark of aging and is characterized by dramatic metabolic reprogramming. To analyze how the fate of labeled methionine is altered during aging, we applied 13C5-Methionine labeling to Drosophila and demonstrated significant changes in the activity of different branches of the methionine metabolism as flies age. We further tested whether targeted degradation of methionine metabolism components would "reset" methionine metabolism flux and extend the fly lifespan. Specifically, we created transgenic flies with inducible expression of Methioninase, a bacterial enzyme capable of degrading methionine and revealed methionine requirements for normal maintenance of lifespan. We also demonstrated that microbiota-derived methionine is an alternative and important source in addition to food-derived methionine. In this genetic model of methionine restriction (MetR), we also demonstrate that either whole-body or tissue-specific Methioninase expression can dramatically extend Drosophila health- and lifespan and exerts physiological effects associated with MetR. Interestingly, while previous dietary MetR extended lifespan in flies only in low amino acid conditions, MetR from Methioninase expression extends lifespan independently of amino acid levels in the food. Finally, because impairment of the methionine metabolism has been previously associated with the development of Alzheimer's disease, we compared methionine metabolism reprogramming between aging flies and a Drosophila model relevant to Alzheimer's disease, and found that overexpression of human Tau caused methionine metabolism flux reprogramming similar to the changes found in aged flies. Altogether, our study highlights Methioninase as a potential agent for health- and lifespan extension.

Tissue-specific down-regulation of S-adenosyl-homocysteine via suppression of dAhcyL1/dAhcyL2 extends health span and life span in Drosophila.

Aging is a risk factor for many human pathologies and is characterized by extensive metabolic changes. Using targeted high-throughput metabolite profiling in Drosophila melanogaster at different ages, we demonstrate that methionine metabolism changes strikingly during aging. Methionine generates the methyl donor S-adenosyl-methionine (SAM), which is converted via methylation to S-adenosyl-homocysteine (SAH), which accumulates during aging. A targeted RNAi screen against methionine pathway components revealed significant life span extension in response to down-regulation of two noncanonical Drosophila homologs of the SAH hydrolase Ahcy (S-adenosyl-L-homocysteine hydrolase [SAHH[), CG9977/dAhcyL1 and Ahcy89E/CG8956/dAhcyL2, which act as dominant-negative regulators of canonical AHCY. Importantly, tissue-specific down-regulation of dAhcyL1/L2 in the brain and intestine extends health and life span. Furthermore, metabolomic analysis of dAhcyL1-deficient flies revealed its effect on age-dependent metabolic reprogramming and H3K4 methylation. Altogether, reprogramming of methionine metabolism in young flies and suppression of age-dependent SAH accumulation lead to increased life span. These studies highlight the role of noncanonical Ahcy enzymes as determinants of healthy aging and longevity.

Dietary Methionine Restriction Improves Gut Health and Alters the Plasma Metabolomic Profile in Rats by Modulating the Composition of the Gut Microbiota.

Dietary methionine restriction (MetR) offers an integrated set of beneficial health effects, including delaying aging, extending health span, preventing fat accumulation, and reducing oxidative stress. This study aimed to investigate whether MetR exerts entero-protective effects by modulating intestinal flora, and the effect of MetR on plasma metabolites in rats. Rats were fed diets containing 0.86% methionine (CON group) and 0.17% methionine (MetR group) for 6 weeks. Several indicators of inflammation, gut microbiota, plasma metabolites, and intestinal barrier function were measured. 16S rRNA gene sequencing was used to analyze the cecal microbiota. The MetR diet reduced the plasma and colonic inflammatory factor levels. The MetR diet significantly improved intestinal barrier function by increasing the mRNA expression of tight junction proteins, such as zonula occludens (ZO)-1, claudin-3, and claudin-5. In addition, MetR significantly increased the levels of short-chain fatty acids (SCFAs) by increasing the abundance of SCFAs-producing Erysipclotxichaceae and Clostridium_sensu_stricto_1 and decreasing the abundance of pro-inflammatory bacteria Proteobacteria and Escherichia-Shigella. Furthermore, MetR reduced the plasma levels of taurochenodeoxycholate-7-sulfate, taurocholic acid, and tauro-ursodeoxycholic acid. Correlation analysis identified that colonic acetate, total colonic SCFAs, 8-acetylegelolide, collettiside I, 6-methyladenine, and cholic acid glucuronide showed a significant positive correlation with Clostridium_sensu_stricto_1 abundance but a significant negative correlation with Escherichia-Shigella and Enterococcus abundance. MetR improved gut health and altered the plasma metabolic profile by regulating the gut microbiota in rats.

Targeting Methionine Addiction of Cancer Cells with Methioninase.

All types of cancer cells are addicted to methionine, which is known as the Hoffman effect. Restricting methionine inhibits the growth and proliferation of all tested types of cancer cells, leaving normal cells unaffected. Targeting methionine addiction with methioninase (METase), either alone or in combination with common cancer chemotherapy drugs, has been shown as an effective and safe therapy in various types of cancer cells and animal cancer models. About six years ago, recombinant METase (rMETase) was found to be able to be taken orally as a supplement, resulting in anecdotal positive results in patients with advanced cancer. Currently, there are 8 published clinical studies on METase, including two from the 1990s and six more recent ones. This review focuses on the results of clinical studies on METase-mediated methionine restriction, in particular, on the dosage of oral rMETase taken alone as a supplement or in combination with common chemotherapeutic agents in patients with advanced cancer.

Lysosomal activity regulates Caenorhabditis elegans mitochondrial dynamics through vitamin B12 metabolism.

Mitochondrial fission and fusion are highly regulated by energy demand and physiological conditions to control the production, activity, and movement of these organelles. Mitochondria are arrayed in a periodic pattern in Caenorhabditis elegans muscle, but this pattern is disrupted by mutations in the mitochondrial fission component dynamin DRP-1. Here we show that the dramatically disorganized mitochondria caused by a mitochondrial fission-defective dynamin mutation is strongly suppressed to a more periodic pattern by a second mutation in lysosomal biogenesis or acidification. Vitamin B12 is normally imported from the bacterial diet via lysosomal degradation of B12-binding proteins and transport of vitamin B12 to the mitochondrion and cytoplasm. We show that the lysosomal dysfunction induced by gene inactivations of lysosomal biogenesis or acidification factors causes vitamin B12 deficiency. Growth of the C. elegans dynamin mutant on an Escherichia coli strain with low vitamin B12 also strongly suppressed the mitochondrial fission defect. Of the two C. elegans enzymes that require B12, gene inactivation of methionine synthase suppressed the mitochondrial fission defect of a dynamin mutation. We show that lysosomal dysfunction induced mitochondrial biogenesis, which is mediated by vitamin B12 deficiency and methionine restriction. S-adenosylmethionine, the methyl donor of many methylation reactions, including histones, is synthesized from methionine by S-adenosylmethionine synthase; inactivation of the sams-1 S-adenosylmethionine synthase also suppresses the drp-1 fission defect, suggesting that vitamin B12 regulates mitochondrial biogenesis and then affects mitochondrial fission via chromatin pathways.