SHMT2 Expression Research Articles

Silencing SHMT2 inhibits the progression of tongue squamous cell carcinoma through cell cycle regulation

BackgroundSerine hydroxymethyltransferase 2 (SHMT2) is a vital metabolic enzyme in one carbon metabolism catalyzing the conversion of serine to glycine, which has been reported to play a crucial role in the progression of tumors. However, its function in tongue squamous cell carcinoma (TSCC) remains unclear.MethodsSHMT2 expression was analyzed using samples in online databases, and was assessed through immunohistochemistry staining of collected clinical specimens. The correlation between SHMT2 expression and the cell cycle was predicted through bioinformatic analysis, including weighted gene co-expression network analysis (WGCNA) and gene set enrichment analysis (GSEA). After transfection with siRNA, CCK8 assay, Edu staining, flow cytometry, trans-well assay, and wound healing experiments were performed to verify the functional role of SHMT2 in vitro. A stable cell line with SHMT2 silencing was established to detect the oncogenic function of SHMT2 in vivo.ResultsThe expression of SHMT2 was up-regulated in TSCC tissues and cell lines compared with normal groups, and highly expressed SHMT2 significantly indicated a poorer clinical outcome for TSCC patients. Bioinformatic analysis found that high expression of SHMT2 was closely related with biologic process including cell cycle and cell cycle G1/S transition. Down regulating of SHMT2 significantly suppressed the proliferation, invasive and migrative ability of TSCC cells, and induced the prolongation of the G1 phase of the cell cycle in vitro. Furthermore, western blot showed that cell cycle-related regulators such as cyclin-dependent kinase 4 (CDK4) and cyclinD1 expression levels were decreased, while the expression levels of the cyclin-dependent kinase inhibitors p21Cip1 and p27Kip1 were increased after SHMT2 knockdown. Silencing SHMT2 in the HN6 cell line using short hairpin RNA also impeded tumor growth in vivo.ConclusionsOverexpression of SHMT2 in TSCC indicated low survival rates, and was associated with aggressive behaviors of TSCC. It was also found to be involved in cell cycle regulation of TSCC cells. SHMT2 may serve as a novel prognostic indicator of TSCC.

Evaluating the clinical significance of SHMT2 and its co-expressed gene in human kidney cancer

BackgroundKidney cancer is one of the most common cancers in the world. It is necessary to clarify its underlying mechanism and find its prognostic biomarkers. Current studies showed that SHMT2 may be participated in several kinds of cancer.MethodsOur studies investigated the expression of SHMT2 in kidney cancer by Oncomine, Human Protein Atlas database and ULCAN database. Meanwhile, we found its co-expression gene by cBioPortal online tool and validated their relationship in A498 and ACHN cells by cell transfection, western blot and qRT-PCR. Besides these, we also explored their prognostic values via the Kaplan–Meier plotter database in different types of kidney cancer patients.ResultsSHMT2 was found to be increased in 7 kidney cancer datasets, compared to normal renal tissues. For the cancer stages, ages and races, there existed significant difference in the expression of SHMT2 among different groups by mining of the UALCAN database. High SHMT2 expression is associated with poor overall survival in patients with kidney cancer. Among all co-expressed genes, NDUFA4L2 and SHMT2 had a high co-expression efficient. SHMT2 overexpression led to the increased expression of NDUFA4L2 at both mRNA and protein levels. Like SHMT2, overexpressed NDUFA4L2 also was associated with worse overall survival in patients with kidney cancer.ConclusionBased on above results, overexpressed SHMT2 and its co-expressed gene NDUFA4L2 were all correlated with the prognosis in kidney cancer. The present study might be benefit for better understanding the clinical significance of SHMT2 and provided a potential therapeutic target for kidney cancer in future.

Increased Expression of SHMT2 Is Associated With Poor Prognosis and Advanced Pathological Grade in Oral Squamous Cell Carcinoma.

This study focused on the expression of mitochondrial serine hydroxymethyltransferase (SHMT2) in oral squamous cell carcinoma (OSCC) and its correlation with clinical traits and the prognosis of OSCC patients. Immunochemical staining and Western blotting were used to quantify the expression of SHMT2 and related immune markers in OSCC. Using OSCC microarrays and The Cancer Genome Atlas (TCGA) database, we evaluated the association between SHMT2 and various clinical traits. We found that increased expression of SHMT2 was detected in OSCC and correlated with advanced pathological grade and recurrence of OSCC. By a multivariate Cox proportional hazard model, high expression of SHMT2 was shown to indicate a negative prognosis. In addition, in the OSCC microenvironment, increasing the expression of SHMT2 was associated with high expression levels of programmed cell death-ligand 1 (PD-L1), CKLF-like MARVEL transmembrane domain containing 6 (CMTM6), V-type immunoglobulin domain-containing suppressor (VISTA), B7-H4, Slug, and CD317. In the future, more effort will be required to investigate the role of SHMT2 in the OSCC microenvironment.

Evaluation of LKB1 and Serine-Glycine Metabolism Pathway Genes (SHMT1 and GLDC) Expression in AML.

LKB1 is a significant tumor suppressor and epigenetic regulator playing a vital role in different types of cancers. SHMT1 and GLDC are two critical genes of the epigenetic pathway influenced by LKB1. As epigenetic is the major cause of AML pathogenesis, this study aimed at investigating LKB1, SHMT1, and GLDC gene expression levels in acute myeloid leukemia patients. The present study was conducted on LKB1, SHMT1, and GLDC gene expression levels in 60 de novo AML samples and 30 normal controls using real-time RT-PCR. The results showed that LKB1 and SHMT1 have respectively a significantly lower (P < 0.05) and higher (P < 0.05) expression level than that of normal controls. Furthermore, the correlation between LKB1 with SHMT1 and GLDC was significant and positive (P value: 0.015, r: 0.299). Positive findings confirm that metabolic pathways alongside the LKB1 association drive the epigenetic axis and its substrate production. Therefore, it can be concluded that the newly-discovered pathway in the pathogenesis of this disease provides new insights into the design of therapeutic targets.

Abstract 5713: Reprogramming of serine metabolism during breast cancer progression

Abstract The causes and consequences of metabolic reprogramming during human breast cancer metastasis remain largely unknown. We performed metabolomics in the human triple-negative breast cancer cell line MDA-MB-231 (231-Parental) and its metastatic subclones that display tissue-tropism towards the brain (831-BrM), the bone (1833-BoM), and the lung (4175-LM). Using molecular and metabolic flux analysis, we uncovered that the mitochondrial serine and one-carbon (1C) unit pathway is upregulated in the metastatic subclones. Inhibition of the first rate-limiting enzyme of the pathway, serine hydroxymethyltransferase (SHMT2), potently suppresses proliferation of metastatic subclones in culture and impairs growth of lung metastatic subclones at both primary and metastatic sites in mice. In addition to breast cancer, a few other cancer types, such as adrenocortical carcinoma (ACC) and kidney chromophobe cell carcinoma (KICH), also display increased SHMT2 expression during disease progression. Moreover, we found that metastatic cells are exquisitely adapted to low serine conditions by synthesizing serine de novo from glucose to generate 1C units, and blocking serine catabolism abrogates metastatic growth under serine deprivation. How do metastatic breast cancer cells acquire new metabolic properties such as de novo serine synthesis? We observed that 231-Parental cells grown in media lacking serine for up to ten passages exhibited metastatic cell-like metabolic properties. Subsequent RNA-sequencing revealed dramatic global gene expression changes during serine starvation in more primary tumor-like cells. Several pathways involved in metastasis such as TNFα signaling, mTOR1 signaling, and Ras signaling were modulated upon serine starvation. These data suggest that the availability of the nonessential amino acid serine may play a key regulatory role in breast cancer progression and metastasis, and highlight the potential for metabolite supplementation to block or halt these transformations. Citation Format: Albert Mao Li, Gregory S. Ducker, Yang Li, Jose A. Seoane, Yiren Xiao, Stavros Melemenidis, Yiren Zhou, Ling Liu, Sakari Vanharanta, Edward E. Graves, Erinn B. Rankin, Christina Curtis, Joan Massague, Joshua D. Rabinowitz, Craig B. Thompson, Jiangbin Ye. Reprogramming of serine metabolism during breast cancer progression [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5713.

Serine-dependent redox homeostasis regulates glioblastoma cell survival

BackgroundThe amino acid serine is an important substrate for biosynthesis and redox homeostasis. We investigated whether glioblastoma (GBM) cells are dependent on serine for survival under conditions of the tumour microenvironment.MethodsSerine availability in GBM cells was modulated pharmacologically, genetically and by adjusting serine and glycine concentrations in the culture medium. Cells were investigated for regulation of serine metabolism, proliferation, sensitivity to hypoxia-induced cell death and redox homeostasis.ResultsHypoxia-induced expression of phosphoglycerate dehydrogenase (PHGDH) and the mitochondrial serine hydroxymethyltransferase (SHMT2) was observed in three of five tested glioma cell lines. Nuclear factor erythroid 2-related factor (Nrf) 2 activation also induced PHGDH and SHMT2 expression in GBM cells. Low levels of endogenous PHGDH as well as PHGDH gene suppression resulted in serine dependency for cell growth. Pharmacological inhibition of PHGDH with CBR-5884 reduced proliferation and sensitised cells profoundly to hypoxia-induced cell death. This effect was accompanied by an increase in reactive oxygen species and a decrease in the NADPH/NADP+ ratio. Similarly, hypoxia-induced cell death was enhanced by PHGDH gene suppression and reduced by PHGDH overexpression.ConclusionsSerine facilitates adaptation of GBM cells to conditions of the tumour microenvironment and its metabolism could be a plausible therapeutic target.

Glycine by MR spectroscopy is an imaging biomarker of glioma aggressiveness.

High-grade gliomas likely remodel the metabolic machinery to meet the increased demands for amino acids and nucleotides during rapid cell proliferation. Glycine, a non-essential amino acid and intermediate of nucleotide biosynthesis, may increase with proliferation. Non-invasive measurement of glycine by magnetic resonance spectroscopy (MRS) was evaluated as an imaging biomarker for assessment of tumor aggressiveness. We measured glycine, 2-hydroxyglutarate (2HG), and other tumor-related metabolites in 35 glioma patients using an MRS sequence tailored for co-detection of glycine and 2HG in gadolinium-enhancing and non-enhancing tumor regions on 3T MRI. Glycine and 2HG concentrations as measured by MRS were correlated with tumor cell proliferation (MIB-1 labeling index), expression of mitochondrial serine hydroxymethyltransferase (SHMT2), and glycine decarboxylase (GLDC) enzymes, and patient overall survival. Elevated glycine was strongly associated with presence of gadolinium enhancement, indicating more rapidly proliferative disease. Glycine concentration was positively correlated with MIB-1, and levels higher than 2.5 mM showed significant association with shorter patient survival, irrespective of isocitrate dehydrogenase status. Concentration of 2HG did not correlate with MIB-1 index. A high glycine/2HG concentration ratio, >2.5, was strongly associated with shorter survival (P < 0.0001). GLDC and SHMT2 expression were detectable in all tumors with glycine concentration, demonstrating an inverse correlation with GLDC. The data suggest that aggressive gliomas reprogram glycine-mediated one-carbon metabolism to meet the biosynthetic demands for rapid cell proliferation. MRS evaluation of glycine provides a non-invasive metabolic imaging biomarker that is predictive of tumor progression and clinical outcome. 1. Glycine and 2-hydroxyglutarate in glioma patients are precisely co-detected using MRS at 3T.2. Tumors with elevated glycine proliferate and progress rapidly.3. A high glycine/2HG ratio is predictive of shortened patient survival.

Metabolic Profiling Reveals a Dependency of Human Metastatic Breast Cancer on Mitochondrial Serine and One-Carbon Unit Metabolism.

Breast cancer is the most common cancer among American women and a major cause of mortality. To identify metabolic pathways as potential targets to treat metastatic breast cancer, we performed metabolomics profiling on the breast cancer cell line MDA-MB-231 and its tissue-tropic metastatic subclones. Here, we report that these subclones with increased metastatic potential display an altered metabolic profile compared with the parental population. In particular, the mitochondrial serine and one-carbon (1C) unit pathway is upregulated in metastatic subclones. Mechanistically, the mitochondrial serine and 1C unit pathway drives the faster proliferation of subclones through enhanced de novo purine biosynthesis. Inhibition of the first rate-limiting enzyme of the mitochondrial serine and 1C unit pathway, serine hydroxymethyltransferase (SHMT2), potently suppresses proliferation of metastatic subclones in culture and impairs growth of lung metastatic subclones at both primary and metastatic sites in mice. Some human breast cancers exhibit a significant association between the expression of genes in the mitochondrial serine and 1C unit pathway with disease outcome and higher expression of SHMT2 in metastatic tumor tissue compared with primary tumors. In addition to breast cancer, a few other cancer types, such as adrenocortical carcinoma and kidney chromophobe cell carcinoma, also display increased SHMT2 expression during disease progression. Together, these results suggest that mitochondrial serine and 1C unit metabolism plays an important role in promoting cancer progression, particularly in late-stage cancer. IMPLICATIONS: This study identifies mitochondrial serine and 1C unit metabolism as an important pathway during the progression of a subset of human breast cancers.

High Expression of Serine Hydroxymethyltransferase 2 Indicates Poor Prognosis of Gastric Cancer Patients

BackgroundSerine hydroxymethyltransferase (SHMT) is the enzyme that catalyzes the reversible conversion of serine to glycine and tetrahydrofolate-bound one-carbon unit. Upregulation of SHMT2 has been observed in a variety of cancers, but the expression profile and clinical value of SHMT2 in gastric cancer (GC) are still unknown.Material/MethodsIn this study, SHMT2 expression was assessed in 130 patients with GC by immunohistochemistry (IHC). mRNA of SHMT2 in GC tissues and normal gastric epithelium was compared with qRT-PCR results. The correlations between SHMT2 and the clinicopathologic factors were analyzed with the chi-square test. Univariate analysis with Kaplan-Meier method was used to estimate the correlations between survival rate and clinicopathologic factors, including SHMT2. The independent prognostic biomarkers were confirmed by multivariate analysis using the Cox-regression hazard model. The function of SHMT2 in progression of GC was assessed by in vitro experiments.ResultsThe percentages of low and high expression of SHMT2 were 46.92% and 53.08%, respectively. SHMT2 mRNA in GC tissue was significantly higher than mRNA in the patient-paired adjacent tissues. In the clinical analysis, SHMT2 expression was notably associated with positive lymphatic invasion. High SHMT2 was also demonstrated to independently predict poor prognosis of GC. After silencing SHMT2, we proved that SHMT2 can promote proliferation and invasion of GC cells.ConclusionsHigh SHMT2 promoted progression and was an independent prognostic biomarker of GC, suggesting that SHMT2 detection would be helpful for stratification of high-risk patients and thus directing personalized treatment.

Shmt2: A Stat3 Signaling New Player in Prostate Cancer Energy Metabolism.

Prostate cancer (PCa) is a multifactorial disease characterized by the aberrant activity of different regulatory pathways. STAT3 protein mediates some of these pathways and its activation is implicated in the modulation of several metabolic enzymes. A bioinformatic analysis indicated a STAT3 binding site in the upstream region of SHMT2 gene. We demonstrated that in LNCaP, PCa cells’ SHMT2 expression is upregulated by the JAK2/STAT3 canonical pathway upon IL-6 stimulation. Activation of SHTM2 leads to a decrease in serine levels, pushing PKM2 towards the nuclear compartment where it can activate STAT3 in a non-canonical fashion that in turn promotes a transient shift toward anaerobic metabolism. These results were also confirmed on FFPE prostate tissue sections at different Gleason scores. STAT3/SHMT2/PKM2 loop in LNCaP cells can modulate a metabolic shift in response to inflammation at early stages of cancer progression, whereas a non-canonical STAT3 activation involving the STAT3/HIF-1α/PKM2 loop is responsible for the maintenance of Warburg effect distinctive of more aggressive PCa cells. Chronic inflammation might thus prime the transition of PCa cells towards more advanced stages, and SHMT2 could represent a missing factor to further understand the molecular mechanisms responsible for the transition of prostate cancer towards a more aggressive phenotype.

Abstract 4246: Association of transcriptional levels of folate-mediated one-carbon metabolism related genes in cancer cell lines with drug treatment response

Abstract Folate-mediated one-carbon metabolism (OCM) is essential for growth and survival of cancer cells. It affects biosynthesis of nucleotides and amino acids, regulation of redox status, methylation of nucleic acids and proteins, and genome maintenance. We investigated whether the response of cancer cells to antitumor therapy treatment may be partially influenced by variation in expression of one-carbon metabolism genes. We used publicly available gene expression data and drug response measures for 251 antitumor agents in 635 cancer cell lines with matching information from the Cancer Cell Line Encyclopedia and the Genomics of Drug Sensitivity in Cancer resources. We examined whether pre-treatment expression levels of OCM-related genes were associated with drug response. Among the 34 OCM genes examined, expression of GART, TYMS, SHMT2, MTR, ALDH2, BHMT, MAT2B, MTHFD2, NNMT, and SLC46A1 showed modest correlations with response to treatment with a variety of antitumor agents. Higher expression levels of the SLC46A1 transporter gene were associated with resistance to multiple drugs, whereas elevated expression of GART, TYMS, SHMT2, MTR, BHMT, and MAT2B was associated with chemosensitivity to multiple antitumor agents. NNMT expression was bimodally distributed and showed different directions of association with various agents. Correlation of increased NNMT expression with sensitivity to dasatinib was validated in the NCI-60 cancer cell line panel. Expression of several OCM genes was strongly associated with expression of multiple components of drug target pathways. For example, expression of both TYMS and GART was strongly positively correlated with BRCA1 expression, NNMT expression was associated with expression of multiple drug target genes including EGFR and ABL2, and the expression of TYMS, DHFR, and SHMT1 was positively correlated with AURKB expression. Pretreatment expression levels of many OCM genes including DHFR, TYMS, ATIC, GART, AHCY, MTHFD1, SLC19A1, and multiple other genes were positively correlated with each other, suggesting their co-regulation. In contrast, NNMT expression was negatively correlated with expression of several other OCM genes. Further studies could investigate whether correlations of expression levels of individual OCM genes with drug response are related to specific metabolic roles of these genes or whether such associations may be due to the general increase in cellular growth and proliferation and tumor progression, which may affect sensitivity to cancer treatment. Citation Format: Julia Krushkal, Suleyman Vural, Dong-Joon Min. Association of transcriptional levels of folate-mediated one-carbon metabolism related genes in cancer cell lines with drug treatment response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4246.

Association of transcriptional levels of folate-mediated one-carbon metabolism-related genes in cancer cell lines with drug treatment response

Folate-mediated one-carbon metabolism is essential for growth and survival of cancer cells. We investigated whether the response of cancer cells to antitumor treatment may be partially influenced by variation in expression of one-carbon metabolism genes. We used cancer cell line information from the Cancer Cell Line Encyclopedia and the Genomics of Drug Sensitivity in Cancer resources to examine whether variation in pretreatment expression of one-carbon metabolism-related genes was associated with response to treatment. GART, TYMS, SHMT2, MTR, ALDH2, BHMT, MAT2B, MTHFD2, NNMT, and SLC46A1 showed modest statistically significant correlations with response to a variety of antitumor agents. Higher expression levels of SLC46A1 were associated with resistance to multiple agents, whereas elevated expression of GART, TYMS, SHMT2, MTR, BHMT, and MAT2B was associated with chemosensitivity to multiple drugs. NNMT expression was bimodally distributed and showed different directions of association with various agents. Correlation of increased NNMT expression with sensitivity to dasatinib was validated in the NCI-60 cancer cell line panel. Pretreatment expression levels were correlated among many one-carbon metabolism genes. Expression of several folate genes was strongly associated with expression of multiple components of drug target pathways. Molecular mechanisms underlying associations of one-carbon metabolism gene with drug response require further investigation.

The Essentiality of Serine and Glycine for Skeletal Muscle Regeneration

Non‐essential amino acids (NEAA), serine (ser) and glycine (gly), are recognized as essential to support proliferation of some cell types, including skeletal muscle (SkM) progenitor cells (MPCs). MPCs and a well‐orchestrated myogenic program are essential for SkM regeneration following injury; impaired regeneration underlies pathological tissue remodeling and functional decline. It is appreciated that the metabolic microenvironment and nutrient availability influence the myogenic process. The objective of this research was to investigate the metabolic and cellular requirements of ser and gly for the regenerative process (MPC expansion, differentiation, and myotube formation) in vitro. Human primary MPCs (hMPCs) were cultured with and without ser/gly and markers of proliferation (live and dead staining, BrdU incorporation, Propidium Iodide cell‐cycle analysis) were assessed; markers of differentiation, and myotube formation (gene and protein expression of select myogenic regulatory factors [MRFs], myosin staining) are being investigated. Additionally, the regulation of the de novo ser synthesis pathway (SSP), ser/gly interconversion (SHMT1, SHMT2), and changes in oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) were determined with/without ser/gly using RNAseq, qPCR, immunoblotting, and a Seahorse bioanalyzer. Ser/gly depletion caused hMPCs to reside in a non‐proliferative state without inducing apoptosis and decreased OCR (p&lt;0.05) but not ECAR (p=0.07), supporting a quiescent metabolic state. BrdU incorporation and cell‐cycle sorting with flow cytometry suggested that depletion of ser/gly inhibits hMPCs from leaving G1 phase. Intriguingly, proliferating hMPCs expressed all SSP enzymes (PHGDH, PSAT1, PSPH). The expression of SSP enzymes, SHMT2, ser transporters, and ATF4 (transcription factor involved in nutrient sensing) increased during ser/gly depletion suggesting ser/gly depletion is sensed by hMPCs and mechanisms to increase ser and gly availability are upregulated. Ser and gly are substrates for multiple metabolic pathways; building blocks for lipids, proteins, and nucleotides; one‐carbon donors; and help maintain cellular (epi)genetic status and redox state. Providing formate (a one‐carbon source), nucleotides, or additional glucose did not rescue proliferation. RNAseq analysis revealed an upregulation of genes involved in the glutathione metabolism pathway. In support of these findings a cell permeable version of glutathione provided a modest rescue to hMPC cell number and intracellular levels of total glutathione and the ratio of reduced to oxidized glutathione were diminished after the ser/gly depletion; glutathione may be a necessary product of ser/gly metabolism. Ongoing RNAseq analysis will allow us to identify potential mechanisms underlying the quiescent‐like state. Ongoing culture experiments will determine the effects of ser/gly depletion on differentiation and myotube formation. This research builds upon recent findings that clearly identify an exogenous requirement of ser and gly for hMPC expansion and challenges the notion that ser and gly are strictly NEAA, particularly in states of tissue regeneration.Support or Funding InformationPresident's Council of Cornell Women and Cornell Division of Nutritional SciencesThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Abstract 5471: EWS-FLI1 reprograms the metabolism of Ewing sarcoma cells via positive regulation of glutamine import and serine-glycine biosynthesis

Abstract Ewing sarcoma (EWS) is a soft tissue and bone tumor found primarily in adolescents and young adults. In most cases of EWS, the chimeric transcription factor, EWS-FLI1 is the primary oncogenic driver. The expression profile of EWS cells reflects EWS-FLI1 binding and activation or repression of transcription. Recent studies have shown EWS-FLI1 deregulates proteins that function in tryptophan metabolism (Mutz et al., 2016, FEBS Lett. 590, 2063) or serine-glycine biosynthesis (Tanner et al., 2017, Mol. Cancer Res., 11, 1517). In our study, we extend these findings by establishing that EWS-FLI1 transcriptionally regulates the expression of enzymes required for serine-glycine biosynthesis and the mitochondrial one-carbon cycle, and the uptake of the alternative nutrient source glutamine, directly. To identify metabolic pathways regulated by EWS-FLI1, we interrogated the expression profiles of EWS-FLI1-silenced TC32 EWS cells. We observed that silencing of EWS-FLI1 results in the decreased expression of genes required for serine-glycine biosynthesis specifically, PHGDH, PSAT1, PSPH, and SHMT2. Using ChIP analysis, we demonstrated that EWS-FLI1 binds specific regulatory regions within these four serine-glycine biosynthesis genes. Also, ectopic expression in 293T cells results in increased expression of PHGDH, PSAT1, PSPH, and SHMT2. Consistent with the ability of EWS cells to synthesize serine and glycine de novo, EWS cells grown in medium depleted of these amino acids exhibit no change in viability. However, EWS cells were sensitive to the depletion of glutamine. Analysis of the expression profiles of EWS-FLI1-silenced TC32 EWS cells showed EWS-FLI1 positively regulates expression of the glutamine transporter, SLC1A5 and that EWS cells require glutamine for glycine synthesis. Next, we examined metabolic processes downstream of serine-glycine biosynthesis and showed that enzymes associated with the mitochondrial one-carbon cycle, MTHFD2 and MTHD1L, are transcriptional targets of EWS-FLI1, but not their cytosolic counterpart MTHFD1. Our data suggests EWS-FLI1 favors activation of enzymes associated with the mitochondrial one-carbon cycle, which provides the reducing equivalents GSH and NADPH. Depletion of EWS-FLI1 or the inhibition of PHGDH reduced the GSH/GSSG and NADPH/NADP ratios in EWS cells resulting in increased production of reactive oxygen species, inducing DNA damage and apoptosis. Importantly, analysis of EWS primary tumor transcriptome data confirmed that the aforementioned metabolism genes we identified as regulated by EWS-FLI1 exhibit increased expression compared with normal tissues. In summary, our study demonstrates that EWS-FLI1 reprograms the metabolism of EWS cells and that serine-glycine metabolism and glutamine uptake are potential vulnerabilities in this tumor type. Citation Format: Nirmalya Sen, Allison M. Cross, Philip L. Lorenzi, Javed Khan, Berkley E. Gryder, Suntae Kim, Natasha J. Caplen. EWS-FLI1 reprograms the metabolism of Ewing sarcoma cells via positive regulation of glutamine import and serine-glycine biosynthesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5471.

EWS-FLI1 reprograms the metabolism of Ewing sarcoma cells via positive regulation of glutamine import and serine-glycine biosynthesis.

Ewing sarcoma (EWS) is a soft tissue and bone tumor that occurs primarily in adolescents and young adults. In most cases of EWS, the chimeric transcription factor, EWS‐FLI1 is the primary oncogenic driver. The epigenome of EWS cells reflects EWS‐FLI1 binding and activation or repression of transcription. Here, we demonstrate that EWS‐FLI1 positively regulates the expression of proteins required for serine‐glycine biosynthesis and uptake of the alternative nutrient source glutamine. Specifically, we show that EWS‐FLI1 activates expression of PHGDH, PSAT1, PSPH, and SHMT2. Using cell‐based studies, we also establish that EWS cells are dependent on glutamine for cell survival and that EWS‐FLI1 positively regulates expression of the glutamine transporter, SLC1A5 and two enzymes involved in the one‐carbon cycle, MTHFD2 and MTHFD1L. Inhibition of serine‐glycine biosynthesis in EWS cells impacts their redox state leading to an accumulation of reactive oxygen species, DNA damage, and apoptosis. Importantly, analysis of EWS primary tumor transcriptome data confirmed that the aforementioned genes we identified as regulated by EWS‐FLI1 exhibit increased expression compared with normal tissues. Furthermore, retrospective analysis of an independent data set generated a significant stratification of the overall survival of EWS patients into low‐ and high‐risk groups based on the expression of PHGDH, PSAT1, PSPH, SHMT2, SLC1A5, MTHFD2, and MTHFD1L. In summary, our study demonstrates that EWS‐FLI1 reprograms the metabolism of EWS cells and that serine‐glycine metabolism or glutamine uptake are potential targetable vulnerabilities in this tumor type.

DATF4 regulation of mitochondrial folate-mediated one-carbon metabolism is neuroprotective

Neurons rely on mitochondria as their preferred source of energy. Mutations in PINK1 and PARKIN cause neuronal death in early-onset Parkinson’s disease (PD), thought to be due to mitochondrial dysfunction. In Drosophila pink1 and parkin mutants, mitochondrial defects lead to the compensatory upregulation of the mitochondrial one-carbon cycle metabolism genes by an unknown mechanism. Here we uncover that this branch is triggered by the activating transcription factor 4 (ATF4). We show that ATF4 regulates the expression of one-carbon metabolism genes SHMT2 and NMDMC as a protective response to mitochondrial toxicity. Suppressing Shmt2 or Nmdmc caused motor impairment and mitochondrial defects in flies. Epistatic analyses showed that suppressing the upregulation of Shmt2 or Nmdmc deteriorates the phenotype of pink1 or parkin mutants. Conversely, the genetic enhancement of these one-carbon metabolism genes in pink1 or parkin mutants was neuroprotective. We conclude that mitochondrial dysfunction caused by mutations in the Pink1/Parkin pathway engages ATF4-dependent activation of one-carbon metabolism as a protective response. Our findings show a central contribution of ATF4 signalling to PD that may represent a new therapeutic strategy. A video abstract for this article is available at https://youtu.be/cFJJm2YZKKM.

Identification of TWIST-interacting genes in prostate cancer.

Prostate cancer is one of the most common cancers in men worldwide, and the number of diagnosed patients has dramatically increased in recent years. Currently, the clinical parameters used to diagnose prostate cancer, such as Gleason score, pathological tumor staging, and prostate-specific antigen (PSA) expression level, are considered insufficient to inform recommendation to guide clinical practice. Thus, identification of a novel biomarker is necessary. TWIST is one of the well-studied targets and is correlated with cancer invasion and metastasis in several human cancers. We have investigated two largest prostate cancer patient cohorts available in GEO database and found that TWIST expression is positive correlated with Gleason score and associated with poorer survival. By using a prostate cancer cohort and a prostate cancer cell line dataset, we have identified three potential downstream targets of TWIST, PPM1A, SRP72 and TBCB. TWIST's prognostic capacity is lost when the gene is mutated. Further investigation in the prostate cancer cohort revealed that gene expression of SERPINA, STX7, PDIA2, FMP5, GP1BB, VGLL4, KCNMA1, SHMT2, SAA4 and DIDO1 influence the prognostic significance of TWIST and vice versa. Importantly, eight out of these ten genes are prognostic indicator by itself. In conclusion, our study has further confirmed that TWIST is a prognostic marker in prostate cancer, identified its potential downstream targets and genes that could possibly give additional prognostic value to predict TWIST-mediated prostate cancer progression.

The importance of mitochondrial folate enzymes in human colorectal cancer.

Folate plays a pivotal role in the one-carbon metabolism needed for methylation reactions, nucleotide synthesis, and DNA repair. Although folate metabolism was recently shown to be associated with carcinogenesis in some solid tumors, the importance of folate metabolism in colorectal cancer remains unclear. In the present investigation we found that expression of three mitochondrial folate metabolic enzymes, serine hydroxymethyl transferase (SHMT2), methylenetetrahydrofolate dehydrogenase (MTHFD2) and aldehyde dehydrogenase1 family memberL2 (ALDH1L2), were upregulated in human colorectal tumor tissues compared to normal tissues. Colorectal cancer tissue samples were obtained from 117consecutive patients. We evaluated the expression of the enzymes with immunohistochemical analysis and determined their relevance to clinicopathological characteristics and prognosis. Rates of recurrence-free survival(RFS) and overall survival(OS) in patients with high expression of SHMT2, MTHFD2 and ALDH1L2 tended to be lower than in patients with low expression of SHMT2, MTHFD2 and ALDH1L2 (P=0.446 and P=0.337, P=0.099 and P=0.064, P=0.178 and P=0.257, respectively). Notably, the combined high expression of SHMT2, MTHFD2 and ALDH1L2 (triple high) was more highly associated with poor prognosis than the individual expression levels (RFS; P=0.004 and OS; P=0.037). A multivariate analysis showed that triple high expression was independently associated with RFS (P=0.017). These findings suggested that mitochondrial folate metabolic enzymes could provide a potential therapeutic strategy for treating colorectal cancer.

Expression of serine/glycine metabolism-related proteins is different according to the thyroid cancer subtype.

BackgroundThe aim of this study was to investigate the expression and clinical implications of proteins related to serine/glycine metabolism in different subtypes of thyroid cancer.MethodsTissue microarray (TMA) was constructed with tissues from 557 thyroid cancers, consisting of 244 papillary thyroid carcinomas (PTC), 112 follicular carcinomas (FC), 70 medullary carcinomas (MC), 23 poorly differentiated carcinomas (PDC), and 8 anaplastic carcinomas (AC). Immunohistochemical staining of the serine/glycine metabolism-related molecules phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase, (PSAT), phosphoserine phosphatase (PSPH), serine hydromethyl transferase (SHMT), and glycine decarboxylase (GLDC) was performed with the TMA blocks and the results were analyzed together with clinicopathologic parameters.ResultsThe expression of serine/glycine metabolism-related proteins differed among thyroid cancer subtypes. The expression rate of PHGDH (p < 0.001), PSAT1 (p = 0.001), PSPH (p = 0.008), and tumoral SHMT1 (p < 0.001) was higher in PDC and PTC (78.3, 21.7, 21.7, 30.4 and 63.4, 18.6, 12.8, 31.4 %, respectively), and lowest in MC (15.7, 1.4, 0.0, 10.0 %). Stromal SHMT1 expression was highest in AC (62.5 %) and absent in all FC (p < 0.001). In PTC, positivity for PSPH (p = 0.041), tumoral SHMT1 (p = 0.018), and stromal SHMT1 (p < 0.001) expression was higher in the conventional type compared to follicular type (14.1 versus 2.5 %, 33.6 versus 15.0 %, 42.1 versus 10.0 %, respectively). BRAF V600E mutation was associated with a higher rate of PHGDH (p < 0.001), PSAT1 (p = 0.001), PSPH (p < 0.001), tumoral SHMT1 (p = 0.001), stromal SHMT1 (p < 0.001), and GLDC (p < 0.001) expression compared to non-mutant cases (73.5 versus 40.6 %, 23.1 versus 8.5 %, 17.6 versus 1.9 %, 37.0 versus 18.9 %, 45.8 versus 21.7 %, 21.8 versus 6.6 %, respectively). In univariate analysis, stromal SHMT1 expression was associated with shorter disease-free survival (p = 0.015) in follicular variant PTC, and GLDC positivity was associated with shorter overall survival (OS) in sclerotic stromal type (p = 0.002). In FC, minimally invasive type, PSPH positivity correlated with shorter OS (p = 0.045) and in MC, PHGDH positivity correlated with shorter OS (p = 0.034).ConclusionThe expression of serine/glycine metabolism-related proteins differs among different thyroid cancer types, with a higher rate of expression in PDC and PTC, and lower rate of expression in MC. In PTC, the rate of expression is lower in the follicular variant and higher in cases with BRAF V600E mutation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-016-0915-8) contains supplementary material, which is available to authorized users.

The Role of Serine Hydroxymethyltransferase and Methylene‐Tetrahydrofolate Dehydrogenase in Genome Stability

The conversion of tetrahydrofolate (THF) to 5,10‐methyleneTHF is catalyzed by the isozymes serine hydroxymethyltransferase 1 and 2 (SHMT1, SHMT2) and the trifunctional enzyme methylenetetrahydrofolate dehydrogenase 1 (MTHFD1). 5,10‐methyleneTHF is a cofactor for the enzyme thymidylate synthase (TYMS) in the conversion of deoxyuridylate (dUMP) to thymidylate (dTMP) via one‐carbon metabolism. De novo dTMP synthesis is critical to prevent uracil misincoporation and double stranded breaks (DSBs). The objective of this experiment is to observe the effects of SHMT and MTHFD1 knockdown and arsenic exposure on the thymidylate biosynthesis pathway and genome stability. Reduced SHMT1, SHMT2, and MTHFD1 expression, either alone or in combination, led to a greater percentage of average nuclear area displaying the signal for γH2AX phosphorylation, indicating that knockdown of these proteins increases the extent of DSBs in DNA of affected cells. Arsenic induced uracil incorporation into DNA and increased the extent of genome instability without affecting de novo purine biosynthesis. These data indicate that both SHMT and MTHFD1 contribute to maintenance of genome stability. Supported by Public Health Services grant HD059120 to PJS.