PSPH promotes melanoma growth and metastasis by metabolic deregulation-mediated transcriptional activation of NR4A1

Serine metabolism in tumor progression and immunotherapy

Serine plays a vital role in various metabolic processes including the synthesis of proteins and other amino acids, which are essential for the cell proliferation and growth. Cancer cells either absorb exogenous serine or produce it through the serine synthesis pathway, enabling the generation of intracellular glycine and one-carbon units, which are crucial for nucleotide biosynthesis. This metabolic process, referred to as serine-glycine-one-carbon (SGOC) metabolism, is essential for tumorigenesis and exhibits considerable complexity and clinical significance. Enzymes involved in the SGOC pathway are linked to tumor growth, metastasis, and resistance to therapies. The SGOC pathway is a vital metabolic network that facilitates cell survival and proliferation, especially in aggressive cancers. Understanding how this network is regulated is crucial for tackling tumor heterogeneity and recurrence. This review emphasizes recent advancements in understanding the roles and effects of the SGOC metabolic pathway in the context of cancer progression. Additionally, it outlines the complex influences of the SGOC metabolic pathway on the tumor microenvironment (TME), offering potential strategies to enhance cancer immunotherapy.

PSPH promotes the proliferation and metastasis of esophageal squamous cell carcinoma through MAPK signaling pathways

Esophageal squamous cell carcinoma (ESCC) is an aggressive malignancy with limited therapeutic options and poor prognosis, underscoring the urgent need for novel molecular targets. Here, we identify phosphoserine phosphatase (PSPH) as a key oncogenic driver in ESCC. This study systematically investigated the oncogenic functions of PSPH in ESCC progression and the associated molecular mechanisms. Functional studies revealed that PSPH overexpression markedly enhanced ESCC cell proliferation, migration, and invasion in vitro, while PSPH knockdown exerted opposing effects. Mechanistically, transcriptomic and phosphoproteomic analyses identified the mitogen-activated protein kinase (MAPK) pathway as the key downstream effector of PSPH. In vivo xenograft studies corroborated these findings, demonstrating that PSPH overexpression markedly promoted tumor growth. Notably, the pharmacological inhibitor of c-Jun N-terminal kinase (JNK) effectively abrogated PSPH-induced tumor progression, unequivocally establishing the MAPK pathway as the dominant mediator of PSPH oncogenic functions. Our findings establish PSPH as a key driver of ESCC progression, promoting migration, proliferation, and invasion via MAPK signaling activation. These results position PSPH as a promising therapeutic target for improving outcomes in patients with ESCC.

The role and research progress of serine metabolism in tumor cells

Serine is crucial for tumor initiation, progression, and adaptive immunity. Metabolic pathways for serine synthesis, acquisition, and utilization in tumors and tumor-associated cells are influenced by various physiological factors and the tumor microenvironment, leading to metabolic reprogramming and amplification. Excessive serine metabolism promotes abnormal macromolecule biosynthesis, mitochondrial dysfunction, and epigenetic modifications, driving malignant transformation, proliferation, metastasis, immune suppression, and drug resistance in tumor cells. Restricting dietary serine intake or reducing the expression of serine synthetic enzymes can effectively slow tumor growth and extend patient survival. Consequently, targeting serine metabolism has emerged as a novel and promising research focus in cancer research. This paper reviews serine metabolic pathways and their roles in tumor development. It summarizes the influencing factors of serine metabolism. The article explores the significance of serine synthesis and metabolizing enzymes, along with related biomarkers, in tumor diagnosis and treatment, providing new insights for developing targeted therapies that modulate serine metabolism in cancer.

Abnormal changes in metabolites caused by m6A methylation modification: The leading factors that induce the formation of immunosuppressive tumor microenvironment and their promising potential for clinical application

BACKGROUND

N6-methyladenosine (m6A) RNA methylation modifications have been widely implicated in the metabolic reprogramming of various cell types within the tumor microenvironment (TME) and are essential for meeting the demands of cellular growth and maintaining tissue homeostasis, enabling cells to adapt to the specific conditions of the TME. An increasing number of research studies have focused on the role of m6A modifications in glucose, amino acid and lipid metabolism, revealing their capacity to induce aberrant changes in metabolite levels. These changes may in turn trigger oncogenic signaling pathways, leading to substantial alterations within the TME. Notably, certain metabolites, including lactate, succinate, fumarate, 2-hydroxyglutarate (2-HG), glutamate, glutamine, methionine, S-adenosylmethionine, fatty acids and cholesterol, exhibit pronounced deviations from normal levels. These deviations not only foster tumorigenesis, proliferation and angiogenesis but also give rise to an immunosuppressive TME, thereby facilitating immune evasion by the tumor.

AIM OF REVIEW

The primary objective of this review is to comprehensively discuss the regulatory role of m6A modifications in the aforementioned metabolites and their potential impact on the development of an immunosuppressive TME through metabolic alterations.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review aims to elaborate on the intricate networks governed by the m6A-metabolite-TME axis and underscores its pivotal role in tumor progression. Furthermore, we delve into the potential implications of the m6A-metabolite-TME axis for the development of novel and targeted therapeutic strategies in cancer research.

Metabolic insights into tumor lymph node metastasis in melanoma

Although accounting for only a small amount of skin cancers, melanoma contributes prominently to skin cancer-related deaths, which are mostly caused by metastatic diseases, and lymphatic metastasis constitutes the main route. In this review, we concentrate on the metabolic mechanisms of tumor lymph node (LN) metastasis in melanoma. Two hypotheses of melanoma LN metastasis are introduced, which are the premetastatic niche (PMN) and parallel progression model. Dysregulation of oxidative stress, lactic acid concentration, fatty acid synthesis, amino acid metabolism, autophagy, and ferroptosis construct the metabolic mechanisms in LN metastasis of melanoma. Moreover, melanoma cells also promote LN metastasis by interacting with non-tumor cells through metabolic reprogramming in TIME. This review will deepen our understanding of the mechanism of lymph node metastasis in melanoma.

Knockdown of ERN1 disturbs the expression of phosphoserine aminotransferase 1 and related genes in glioblastoma cells

BACKGROUND

Endoplasmic reticulum stress and synthesis of serine are essential for tumor growth, but the mechanism of their interaction is not clarified yet. The overarching goal of this work was to investigate the impact of ERN1 (endoplasmic reticulum to nucleus signaling 1) inhibition on the expression of serine synthesis genes in U87MG glioblastoma cells concerning the suppression of cell proliferation.

METHODS

Wild type U87MG glioblastoma cells and their clones with overexpression of transgenes dnERN1 (without cytoplasmic domain of ERN1) and dnrERN1 (with mutation in endoribonuclease of ERN1), and empty vector (as control) were used. The silencing of ERN1 and XBP1 was also used to inhibition of ERN1 and its function. Gene expression was measured by qPCR.

RESULTS

We show that the expression of PSAT1 and several other related to serine synthesis genes is suppressed in cells with ERN1 inhibition by dissimilar mechanisms: PHGDH gene through ERN1 protein kinase, because its expression was resistant to inhibition of ERN1 endoribonuclease, but ATF4 gene via endoribonuclease of ERN1. However, in the control of PSAT1 and PSPH genes both enzymatic activities of ERN1 signaling protein are involved. At the same time, ERN1 knockdown strongly increased SHMT1 expression, which controls serine metabolism and enhances the proliferation and invasiveness of glioma cells. The level of microRNAs, which have binding sites in PSAT1, SHMT1, and PSPH mRNAs, was also changed in cells harboring dnERN1 transgene. Inhibition of ERN1 suppressed cell proliferation and enzymatic activity of PHGDH, a rate-limiting enzyme for serine synthesis.

CONCLUSION

Changes in the expression of phosphoserine aminotransferase 1 and other genes related to serine synthesis are mediated by diverse ERN1-dependent mechanisms and contributed to suppressed proliferation and enhanced invasiveness of ERN1 knockdown glioblastoma cell.

Mechanism insights and therapeutic intervention of tumor metastasis: latest developments and perspectives

Metastasis remains a pivotal characteristic of cancer and is the primary contributor to cancer-associated mortality. Despite its significance, the mechanisms governing metastasis are not fully elucidated. Contemporary findings in the domain of cancer biology have shed light on the molecular aspects of this intricate process. Tumor cells undergoing invasion engage with other cellular entities and proteins en route to their destination. Insights into these engagements have enhanced our comprehension of the principles directing the movement and adaptability of metastatic cells. The tumor microenvironment plays a pivotal role in facilitating the invasion and proliferation of cancer cells by enabling tumor cells to navigate through stromal barriers. Such attributes are influenced by genetic and epigenetic changes occurring in the tumor cells and their surrounding milieu. A profound understanding of the metastatic process's biological mechanisms is indispensable for devising efficacious therapeutic strategies. This review delves into recent developments concerning metastasis-associated genes, important signaling pathways, tumor microenvironment, metabolic processes, peripheral immunity, and mechanical forces and cancer metastasis. In addition, we combine recent advances with a particular emphasis on the prospect of developing effective interventions including the most popular cancer immunotherapies and nanotechnology to combat metastasis. We have also identified the limitations of current research on tumor metastasis, encompassing drug resistance, restricted animal models, inadequate biomarkers and early detection methods, as well as heterogeneity among others. It is anticipated that this comprehensive review will significantly contribute to the advancement of cancer metastasis research.

L-serine deficiency: on the properties of the Asn133Ser variant of human phosphoserine phosphatase

The non-essential amino acid L-serine is involved in a number of metabolic pathways and in the brain its level is largely due to the biosynthesis from the glycolytic intermediate D-3-phosphoglycerate by the phosphorylated pathway (PP). This cytosolic pathway is made by three enzymes proposed to generate a reversible metabolon named the "serinosome". Phosphoserine phosphatase (PSP) catalyses the last and irreversible step, representing the driving force pushing L-serine synthesis. Genetic defects of the PP enzymes result in strong neurological phenotypes. Recently, we identified the homozygous missense variant [NM_004577.4: c.398A > G p.(Asn133Ser)] in the PSPH, the PSP encoding gene, in two siblings with a neurodevelopmental syndrome and a myelopathy. The recombinant Asn133Ser enzyme does not show significant alterations in protein conformation and dimeric oligomerization state, as well as in enzymatic activity and functionality of the reconstructed PP. However, the Asn133Ser variant is less stable than wild-type PSP, a feature also apparent at cellular level. Studies on patients' fibroblasts also highlight a strong decrease in the level of the enzymes of the PP, a partial nuclear and perinuclear localization of variant PSP and a stronger perinuclear aggregates formation. We propose that these alterations contribute to the formation of a dysfunctional serinosome and thus to the observed reduction of L-serine, glycine and D-serine levels (the latter playing a crucial role in modulating NMDA receptors). The characterization of patients harbouring the Asn133Ser PSP substitution allows to go deep into the molecular mechanisms related to L-serine deficit and to suggest treatments to cope with the observed amino acids alterations.

Integrative analysis of proteomics and lipidomic profiles reveal the fat deposition and meat quality in Duroc × Guangdong small spotted pig

Introduction

This study aims to explore the important factors affecting the characteristics of different parts of pork.

Methods

Lipidomics and proteomics methods were used to analyze DAL (differential lipids) and DAPs (differential proteins) in five different parts (longissimus dorsi, belly meat, loin, forelegs and buttocks) of Duhua pig (Duroc × Guangdong small spotted pig), to identify potential pathways affecting meat quality, investigating fat deposition in pork and its lipid-protein interactions.

Results

The results show that TG (triglyceride) is the lipid subclass with the highest proportion in muscle, and the pathway with the most significantly enriched lipids is GP. DAP clustered on several GO terms closely related to lipid metabolism and lipogenesis (lipid binding, lipid metabolism, lipid transport, and lipid regulation). In KEGG analysis, there are two main DAP aggregation pathways related to lipid metabolism, namely Fatty acid degradation and oxidative phosphorylation. In PPI analysis, we screened out 31 core proteins, among which NDUFA6, NDUFA9 and ACO2 are the most critical.

Discussion

PC (phosphatidylcholine) is regulated by SNX5, THBS1, ANXA7, TPP1, CAVIN2, and VDAC2 in the phospholipid binding pathway. TG is regulated by AUH/HADH/ACADM/ACADL/HADHA in the lipid oxidation and lipid modification pathways. Potential biomarkers are rich in SFA, MUFA and PUFA respectively, the amounts of SFA, MUFA and PUFA in the lipid measurement results are consistent with the up- and down-regulation of potential biomarker lipids. This study clarified the differences in protein and lipid compositions in different parts of Duhua pigs and provided data support for revealing the interactions between pork lipids and proteins. These findings provide contributions to the study of intramuscular fat deposition in pork from a genetic and nutritional perspective.

The enzymes of serine synthesis pathway in cancer metastasis

Metastasis, the major cause of cancer mortality, requires cancer cells to reprogram their metabolism to adapt to and thrive in different environments, thereby leaving metastatic cells metabolic characteristics different from their parental cells. Mounting research has revealed that the de novo serine synthesis pathway (SSP), a glycolytic branching pathway that consumes glucose carbons for serine makeup and α-ketoglutarate generation and thus supports the proliferation, survival, and motility of cancer cells, is one such reprogrammed metabolic pathway. During different metastatic cascades, the SSP enzyme proteins or their enzymatic activity are both dynamically altered; manipulating their expression or catalytic activity could effectively prevent the progression of cancer metastasis; and the SSP enzymatic proteins could even conduce to metastasis via their nonenzymatic functions. In this article we overview the SSP dynamics during cancer metastasis and put the focuses on the regulatory role of the SSP in metastasis and the underlying mechanisms that mainly involve cellular anabolism/catabolism, redox balance, and epigenetics, aiming to provide a theoretical basis for the development of therapeutic strategies for targeting metastatic lesions.

Integrated metabolomics revealed the photothermal therapy of melanoma by Mo2C nanosheets: toward rehabilitated homeostasis in metabolome combined lipidome

Melanoma, the most aggressive and life-threatening form of skin cancer, lacks innovative therapeutic approaches and deeper bioinformation. In this study, we developed a photothermal therapy (PTT) based on Mo2C nanosheets to eliminate melanoma while utilizing integrated metabolomics to investigate the metabolic shift of metabolome combined lipidome during PTT at the molecular level. Our results demonstrated that 1 mg ml-1 Mo2C nanosheets could efficiently convert laser energy into heat with a strong and stable photothermal effect (74 ± 0.9 °C within 7 cycles). Furthermore, Mo2C-based PTT led to a rapid decrease in melanoma volume (from 3.299 to 0 cm2) on the sixth day, indicating the effective elimination of melanoma. Subsequent integrated metabolomics analysis revealed significant changes in aqueous metabolites (including organic acids, amino acids, fatty acids, and amines) and lipid classes (including phospholipids, lysophospholipids, and sphingolipids), suggesting that melanoma caused substantial fluctuations in both metabolome and lipidome, while Mo2C-based PTT helped improve amino acid metabolism-related biological events (such as tryptophan metabolism) impaired by melanoma. These findings suggest that Mo2C nanosheets hold significant potential as an effective therapeutic agent for skin tumors, such as melanoma. Moreover, through exploring multidimensional bioinformation, integrated metabolomics technology provides novel insights for studying the metabolic effects of tumors, monitoring the correction of metabolic abnormalities by Mo2C nanosheet therapy, and evaluating the therapeutic effect on tumors.

Metabolic heterogeneity in cancer

Cancer cells rewire their metabolism to survive during cancer progression. In this context, tumour metabolic heterogeneity arises and develops in response to diverse environmental factors. This metabolic heterogeneity contributes to cancer aggressiveness and impacts therapeutic opportunities. In recent years, technical advances allowed direct characterisation of metabolic heterogeneity in tumours. In addition to the metabolic heterogeneity observed in primary tumours, metabolic heterogeneity temporally evolves along with tumour progression. In this Review, we summarize the mechanisms of environment-induced metabolic heterogeneity. In addition, we discuss how cancer metabolism and the key metabolites and enzymes temporally and functionally evolve during the metastatic cascade and treatment.

Lycorine eliminates B-cell acute lymphoblastic leukemia cells by targeting PSAT1 through the serine/glycine metabolic pathway

B-cell acute lymphoblastic leukemia (B-ALL) has been confirmed as the most common malignant hematologic neoplasm among children. A novel antitumor mechanism of lycorine was elucidated in this study. As revealed by the result of this study, lycorine significantly inhibited the growth and proliferation of REH and NALM-6 and induced their apoptosis. The result of the RNA-seq analysis suggested that lycorine targeted PSAT1 of serine/glycine metabolism in B-ALL cells. As indicated by the result of the GSEA analysis, the genes enriched in the amino acid metabolic pathways were down-regulated by lycorine. As revealed by the results of ectopic expression, shRNA knockdown assays, and further liquid-phase tandem mass spectrometry (LC-MS) analysis, lycorine reduced serine/glycine metabolites by down-regulating PSAT1, further disrupting carbon metabolism and eliminating B-ALL cells. Furthermore, lycorine showed a synergistic effect with cytarabine in ALL treatments. Lastly, lycorine significantly down-regulated leukemia progression in the cell line-derived xenograft (CDX) model. In brief, this study has suggested for the first time that lycorine is a promising anti-ALL drug, and a novel amino acid metabolism-associated property of lycorine was identified.

TET protein inhibitors: Potential and limitations

TET proteins (methylcytosine dioxygenases) play an important role in the regulation of gene expression. Dysregulation of their activity is associated with many serious pathogenic states such as oncological diseases. Regulation of their activity by specific inhibitors could represent a promising therapeutic strategy. Therefore, this review describes various types of TET protein inhibitors in terms of their inhibitory mechanism and possible applicability. The potential and possible limitations of this approach are thoroughly discussed in the context of TET protein functionality in living systems. Furthermore, possible therapeutic strategies based on the inhibition of TET proteins are presented and evaluated, especially in the field of oncological diseases.

Single-cell RNA sequencing reveals blastomere heterogeneity of 2-cell embryos in pigs

In mammals, single blastomeres from as early as 2-cell embryos demonstrate heterogeneous developmental capacity and fate decision into different cell lineages. However, mechanisms underlying blastomere heterogeneity of 2-cell embryos remain largely unresolved. Here, we analysed the molecular heterogeneity of full-length mRNAs and their 3'UTR regions, based on the single-cell RNA-seq data of pig 2-cell embryos generated from in vivo fertilization (in vivo), in vitro fertilization (in vitro) and parthenogenetic activation (PA), respectively. First, unsupervised clustering helped discover two different groups of blastomeres for 2-cell pig embryos. Between these two groups of blastomeres in pig 2-cell embryos, 35, 301 and 428 full-length mRNAs respectively in in vivo, in vitro and PA embryo types were identified to be differentially expressed (padj  ≤ .05 and |log2 [fold change]| ≥1) (DE mRNAs), while 92, 89 and 42 mRNAs were shown to be with significantly different 3'UTR lengths (3'UTR DE) (padj  ≤ .05). Gene enrichment for both DE mRNAs and 3'UTR DE mRNAs found multiple signalling pathways, including cell cycle, RNA processing. Few numbers of common DE mRNAs and 3'UTR DE mRNAs existed between in vitro and in vivo blastomeres derived from 2-cell embryos, indicating the larger differences between in vitro and in vivo fertilized embryos. Integrative genomics viewer analysis further identified that 3'UTRs of HSDL2 and SGTA (in vivo), FAM204A and phosphoserine phosphatase (in vitro), PRPF40A and RPIA (PA) had >100 nt average length changes. Moreover, numbers and locations of regulatory elements (polyadenylation site, cytoplasmic polyadenylation element and microRNA binding sites) within 3'UTRs of these DE mRNAs were predicted. These results indicate that molecular heterogeneity existed among blastomeres from different types of pig 2-cell embryos, providing useful information and novel insights into future functional investigation on its relationship with the subsequent embryo development and differentiation.

Serine Metabolic Reprogramming in Tumorigenesis, Tumor Immunity, and Clinical Treatment

Serine has been recently identified as an essential metabolite for oncogenesis, progression, and adaptive immunity. Influenced by many physiologic or tumor environmental factors, the metabolic pathways of serine synthesis, uptake, and usage are heterogeneously reprogrammed and frequently amplified in tumor or tumor-associated cells. The hyperactivation of serine metabolism promotes abnormal cellular nucleotide/protein/lipid synthesis, mitochondrial function, and epigenetic modifications, which drive malignant transformation, unlimited proliferation, metastasis, immunosuppression, and drug resistance of tumor cells. Dietary restriction of serine or phosphoglycerate dehydrogenase depletion mitigates tumor growth and extends the survival of tumor patients. Correspondingly, these findings triggered a boom in the development of novel therapeutic agents targeting serine metabolism. In this study, recent discoveries in the underlying mechanism and cellular function of serine metabolic reprogramming are summarized. The vital role of serine metabolism in oncogenesis, tumor stemness, tumor immunity, and therapeutic resistance is outlined. Finally, some potential tumor therapeutic concepts, strategies, and limitations of targeting the serine metabolic pathway are described in detail. Taken together, this review underscores the importance of serine metabolic reprogramming in tumorigenesis and progression and highlights new opportunities for dietary restriction or selective pharmacologic intervention.

Amino acid metabolic reprogramming in tumor metastatic colonization

Metastasis is considered as the major cause of cancer death. Cancer cells can be released from primary tumors into the circulation and then colonize in distant organs. How cancer cells acquire the ability to colonize in distant organs has always been the focus of tumor biology. To enable survival and growth in the new environment, metastases commonly reprogram their metabolic states and therefore display different metabolic properties and preferences compared with the primary lesions. For different microenvironments in various colonization sites, cancer cells must transfer to specific metabolic states to colonize in different distant organs, which provides the possibility of evaluating metastasis tendency by tumor metabolic states. Amino acids provide crucial precursors for many biosynthesis and play an essential role in cancer metastasis. Evidence has proved the hyperactivation of several amino acid biosynthetic pathways in metastatic cancer cells, including glutamine, serine, glycine, branched chain amino acids (BCAAs), proline, and asparagine metabolism. The reprogramming of amino acid metabolism can orchestrate energy supply, redox homeostasis, and other metabolism-associated pathways during cancer metastasis. Here, we review the role and function of amino acid metabolic reprogramming in cancer cells colonizing in common metastatic organs, including lung, liver, brain, peritoneum, and bone. In addition, we summarize the current biomarker identification and drug development of cancer metastasis under the amino acid metabolism reprogramming, and discuss the possibility and prospect of targeting organ-specific metastasis for cancer treatment.

The role of serine metabolism in lung cancer: From oncogenesis to tumor treatment

Metabolic reprogramming is an important hallmark of malignant tumors. Serine is a non-essential amino acid involved in cell proliferation. Serine metabolism, especially the de novo serine synthesis pathway, forms a metabolic network with glycolysis, folate cycle, and one-carbon metabolism, which is essential for rapidly proliferating cells. Owing to the rapid development in metabolomics, abnormal serine metabolism may serve as a biomarker for the early diagnosis and pathological typing of tumors. Targeting serine metabolism also plays an essential role in precision and personalized cancer therapy. This article is a systematic review of de novo serine biosynthesis and the link between serine and folate metabolism in tumorigenesis, particularly in lung cancer. In addition, we discuss the potential of serine metabolism to improve tumor treatment.

Hypoxia controls the expression of genes responsible for serine synthesis in U87MG cells on ERN1-dependent manner

Objective. Serine synthesis as well as endoplasmic reticulum stress and hypoxia are important factors of malignant tumor growth including glioblastoma. Previous studies have shown that the knockdown of ERN1 (endoplasmic reticulum to nucleus signaling) significantly suppressed the glioblastoma cell proliferation and modified the hypoxia regulation. The present study is aimed to investigate the impact of hypoxia on the expression of PHGDH (phosphoglycerate dehydrogenase), PSAT1 (phosphoserine aminotransferase 1), PSPH (phosphoserine phosphatase), ATF4 (activating transcription factor 4), and SHMT1 (serine hydroxymethyltransferase 1) in U87MG glioblastoma cells in relation to knockdown of ERN1 with the intent to reveal the role of ERN1 signaling pathway on the endoplasmic reticulum stress-dependent regulation of expression of these genes. Methods. The control U87MG glioblastoma cells (transfected by empty vector) and ERN1 knockdown cells (transfected by dominant-negative ERN1) were exposed to hypoxia introduced by dimethyloxalylglycine for 4 h. RNA was extracted from cells and reverse transcribed. The expression level of PHGDH, PSAT1, PDPH, SHMT1, and ATF4 genes was studied by real-time qPCR and normalized to ACTB. Results. It was found that hypoxia up-regulated the expression level of PHGDH, PSAT1, and ATF4 genes in control U87MG cells, but PSPH and SHMT1 genes expression was down-regulated. The expression of PHGDH, PSAT1, and ATF4 genes in glioblastoma cells with knockdown of ERN1 signaling protein was more sensitive to hypoxia, especially PSAT1 gene. At the same time, the expression of PSPH gene in ERN1 knockdown cells was resistant to hypoxia. The expression of SHMT1 gene, encoding the enzyme responsible for conversion of serine to glycine, showed similar negative sensitivity to hypoxia in both control and ERN1 knockdown glioblastoma cells. Conclusion. The results of the present study demonstrate that the expression of genes responsible for serine synthesis is sensitive to hypoxia in gene-specific manner and that ERN1 knockdown significantly modifies the impact of hypoxia on the expression of PHGDH, PSAT1, PSPH, and ATF4 genes in glioblastoma cells and reflects the ERN1-mediated reprograming of hypoxic regulation at gene expression level.

The connection between innervation and metabolic rearrangements in pancreatic cancer through serine

Pancreatic cancer is a kind of aggressive tumor famous for its lethality and intractability, and pancreatic ductal adenocarcinoma is the most common type. Patients with pancreatic cancer often suffer a rapid loss of weight and abdominal neuropathic pain in their early stages and then go through cachexia in the advanced stage. These features of patients are considered to be related to metabolic reprogramming of pancreatic cancer and abundant nerve innervation responsible for the pain. With increasing literature certifying the relationship between nerves and pancreatic ductal adenocarcinoma (PDAC), more evidence point out that innervation's role is not limited to neuropathic pain but explore its anti/pro-tumor functions in PDAC, especially the neural-metabolic crosstalks. This review aims to unite pancreatic cancer's innervation and metabolic rearrangements with terminated published articles. Hopefully, this article could explore the pathogenesis of PDAC and further promote promising detecting or therapeutic measurements for PDAC according to the lavish innervation in PDAC.

Serine and glycine metabolism-related gene expression signature stratifies immune profiles of brain gliomas, and predicts prognosis and responses to immunotherapy

Glioma is one of the most lethal cancers and causes more than 200,000 deaths every year. Immunotherapy was an inspiring therapy for multiple cancers but failed in glioma treatment. The importance of serine and glycine and their metabolism has been well-recognized in the physiology of immune cells and microenvironment in multiple cancers. However, their correlation with prognosis, immune cells, and immune microenvironment of glioma remains unclear. In this study, we investigated the relationships between the expression pattern of serine and glycine metabolism-related genes (SGMGs) and clinicopathological features, prognosis, and tumor microenvironment in glioma based on comprehensive analyses of multiple public datasets and our cohort. According to the expression of SGMGs, we conducted the consensus clustering analysis to stratify all patients into four clusters with remarkably distinctive clinicopathological features, prognosis, immune cell infiltration, and immune microenvironment. Subsequently, a serine and glycine metabolism-related genes signature (SGMRS) was constructed based on five critical SGMGs in glioma to stratify patients into SGMRS high- and low-risk groups and tested for its prognostic value. Higher SGMRS expressed genes associated with the synthesis of serine and glycine at higher levels and manifested poorer prognosis. Besides, we confirmed that SGMRS was an independent prognostic factor and constructed nomograms with satisfactory prognosis prediction performance based on SGMRS and other factors. Analyzing the relationship between SGMRS and immune landscape, we found that higher SGMRS correlated with 'hotter' immunological phenotype and more immune cell infiltration. Furthermore, the expression levels of multiple immunotherapy-related targets, including PD-1, PD-L1, and B7-H3, were positively correlated with SGMRS, which was validated by the better predicted response to immune checkpoint inhibitors. In conclusion, our study explored the relationships between the expression pattern of SGMGs and tumor features and created novel models to predict the prognosis of glioma patients. The correlation of SGMRS with immune cells and microenvironment in gliomas suggested an essential role of serine and glycine metabolism in reforming immune cells and microenvironment. Finally, the results of our study endorsed the potential application of SGMRS to guide the selection of immunotherapy for gliomas.

[Nur77 promotes invasion and migration of gastric cancer cells through the NF-κB/IL-6 pathway]

OBJECTIVE

To analyze the association of Nur77 with overall survival of gastric cancer patients and investigate the role of Nur77 in invasion and migration of gastric cancer cells.

METHODS

Oncomine database was used to analyze the expression of Nur77 in gastric cancer and gastric mucosa tissues, and the distribution characteristics of Nur77 protein between gastric cancer and normal tissues were compared using Human Protein Atlas. GEPIA2 was used to analyze the relationship of Nur77 expression and the patients' survival. The expression of Nur77 in gastric cancer cell lines GES-1, AGS and MKN-45 were detected by Western blotting. The regulatory interactions between IL-6 and Nur77 were verified by transfecting the cells with specific Nur-77 siRNA and Nur-77-overexpressing plasmid. The changes in migration ability of the cells following Nur-77 knockdown were assessed with scratch assay. The effect of Nur-77 overexpression or IL-6 knockdown, or their combination, on migration and invasion of the gastric cancer cells were examined using Transwell assay. The effect of Nur77 expression level on NF-κB/IL-6 pathway activation was analyzed using Western blotting.

RESULTS

Oncomine database showed that gastric cancer tissues expressed a significantly higher level of Nur77 mRNA than normal tissues (P < 0.05). Nur77 expression was detected mostly in the nucleus, and a high Nur77 expression was associated with a poor survival outcome of the patients (P < 0.05). In gastric cancer cells, the high expression of Nur77 participated in the regulation of IL-6. Nur77 silencing significantly lowered the migration ability of the cells (P < 0.05), and IL-6 silencing significantly attenuated the enhanced migration caused by Nur77 overexpression (P < 0.05). Nur77 participates in the activation of NF-κB/IL-6 signaling pathway by regulating the expression of p-p65, p65, p-Stat3 and Stat3.

CONCLUSION

A high Nur77 expression is strongly correlated with a poor prognosis of gastric cancer patients. Nur77 promotes the invasion and migration of gastric cancer cells possibly by regulating the NF-κB/IL-6 signaling pathway.

Phosphoserine phosphatase as an indicator for survival through potentially influencing the infiltration levels of immune cells in neuroblastoma

Introduction: Metabolic deregulation, a hallmark of cancer, fuels cancer cell growth and metastasis. Phosphoserine phosphatase (PSPH), an enzyme of the serine metabolism pathway, has been shown to affect patients’ prognosis in many cancers but its significance in neuroblastoma remains unknown. Here, we show that the functional role and potential mechanism of PSPH and it is correlated with survival of neuroblastoma patients.

Patients and Methods: The TARGET dataset (n = 151) and our hospital-based cases (n = 55) were used for assessing the expression level of PSPH associated with survival in neuroblastoma patients, respectively. Then, in vitro experiments were performed to define the role of PSPH in neuroblastoma. The ESTIMATE and TIMER algorithms were utilized to examine the correlation between PSPH expression level and abundance of immune cells. Further, Kaplan-Meier survival analysis was performed to evaluate the effect of both PSPH and immune cells on patients’ prognosis.

Results: High expression of PSPH was significantly associated with unfavorable overall survival (OS) and event-free survival (EFS) in both the TARGET dataset and our hospital-based cases, and was an independent predictor of OS (hazard ratio, 2.00; 95% confidence intervals, 1.21–3.30, p = 0.0067). In vitro experiments showed that high expression of PSPH significantly promoted cell growth and metastasis. Further, the ESTIMATE result suggested that high expression level of PSPH was negatively associated with low stromal and ESTIMATE score. Specifically, high PSPH expression was found to be negatively associated with CD8⁺ T cell, macrophages and neutrophils, which negatively affected survival of neuroblastoma patients (p < 0.0001, p = 0.0005, and p = 0.0004, respectively).

Conclusion: These findings suggested that PSPH expression could be a promising indicator for prognosis and immunotherapy in neuroblastoma patients by potentially influencing infiltration levels of immune cells.

DEK modulates both expression and alternative splicing of cancer‑related genes

DEK is known to be a potential proto‑oncogene and is highly expressed in gastric cancer (GC); thus, DEK is considered to contribute to the malignant progression of GC. DEK is an RNA‑binding protein involved in transcription, DNA repair, and selection of splicing sites during mRNA processing; however, its precise function remains elusive due to the lack of clarification of the overall profiles of gene transcription and post‑transcriptional splicing that are regulated by DEK. We performed our original whole‑genomic RNA‑Seq data to analyze the global transcription and alternative splicing profiles in a human GC cell line by comparing DEK siRNA‑treated and control conditions, dissecting both differential gene expression and potential alternative splicing events regulated by DEK. The siRNA‑mediated knockdown of DEK in a GC cell line led to significant changes in gene expression of multiple cancer‑related genes including both oncogenes and tumor suppressors. Moreover, it was revealed that DEK regulated a number of alternative splicing in genes which were significantly enriched in various cancer‑related pathways including apoptosis and cell cycle processes. This study clarified for the first time that DEK has a regulatory effect on the alternative splicing, as well as on the expression, of numerous cancer‑related genes, which is consistent with the role of DEK as a possible oncogene. Our results further expand the importance and feasibility of DEK as a clinical therapeutic target for human malignancies including GC.

Phosphoserine phosphatase as a prognostic biomarker in patients with gastric cancer and its potential association with immune cells

Background

Because of dismal prognosis in gastric cancer, identifying relevant prognostic factors is necessary. Phosphoserine phosphatase (PSPH) exhibits different expression patterns in many cancers and has been reported to affect the prognosis of patients with cancer. In this study, we examined the prognostic role of metabolic gene PSPH in gastric cancer based on the TCGA dataset and our hospital–based cohort cases.

Methods

We collected and analysed RNA-seq data of Pan-cancer and gastric cancer in the TCGA dataset and PSPH expression data obtained from immunohistochemical analysis of 243 patients with gastric cancer from Sun Yat-sen University cancer center. Further, Kaplan–Meier survival analysis and Cox analysis were used to assess the effect of PSPH on prognosis. The ESTIMATE and Cibersort algorithms were used to elucidate the relationship between PSPH and the abundance of immune cells using the TCGA dataset.

Results

We observed that PSPH expression displayed considerably high in gastric cancer and it was significantly associated with inferior prognosis (P = 0.043). Surprisingly, there was a significant relationship between lower immune scores and high expression of PSPH (P < 0.05). Furthermore, patients with a low amount of immune cells exhibited poor prognosis (P = 0.046). The expression of PSPH significantly increased in activated memory CD4 T cells, resting NK cells and M0 macrophages (P = 0.037, < 0.001, and 0.005, respectively).

Conclusions

This study highlighted that PSPH influences the prognosis of patients with gastric cancer, and this is associated with the infiltration of tumour immune cells, indicating that PSPH may be a new immune-related target for treating gastric cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-021-02073-0.

Dietary serine supplementation: Friend or foe?

Serine lies at a critical node in biological processes involved in supplying intermediates for redox homeostasis, nucleotide, or lipid biosynthesis and one-carbon metabolism-coupled methyl donor production. Recently, dietary serine supplementation has been reported to modulate cellular serine levels and ameliorate neurological abnormalities induced by serine deficiency. Moreover, growing evidence showed that serine supplementation also alleviates fatty liver, encephalopathy, diabetes mellitus, and related complications, indicating the possibility of serine supplementation as a complementary therapeutic option. However, considering the serine addiction observed in tumorigenesis and tumor development, limitations may exist regarding the application of dietary serine supplementation in patients with cancer. Here, we assess recent research toward the mechanistic understanding of serine supplementation in various diseases to improve our cognition on modulating serine levels in different patients.