SLC25A22 Promotes Proliferation and Survival of Colorectal Cancer Cells With KRAS Mutations and Xenograft Tumor Progression in Mice via Intracellular Synthesis of Aspartate

Crosstalk of glutamine metabolism between cancer-associated fibroblasts and cancer cells

Glutamine (Gln), a critical metabolic substrate, fuels the uncontrolled proliferation of cancer cells. Cancer-associated fibroblasts (CAFs), essential components of the tumor microenvironment, facilitate tumor progression by supplying Gln to cancer cells and driving drug resistance through metabolic reprogramming. This review highlights the key processes of Gln uptake, transport, and catabolism and explores the metabolic crosstalk between CAFs and cancer cells. It also examines the roles of major oncogenic regulators-c-Myc, mTORC, KRAS, p53, and HIF-in controlling Gln metabolism and shaping therapeutic resistance. Current pharmacological approaches targeting Gln metabolism, including enzyme inhibitors and transporter blockers, are discussed alongside emerging therapeutic strategies and ongoing clinical trials. Lastly, we underscore the importance of integrating advanced technologies like artificial intelligence and spatial omics to refine treatment targeting and develop more effective, personalized therapeutic interventions.

Sirtuin 3 Protects Lung Adenocarcinoma from Ferroptosis by Deacetylating and Stabilizing Mitochondrial Glutamate Transporter Solute Carrier Family 25 Member A22

Solute carrier family 25 member A22 (SLC25A22) is a glutamate transporter in the inner mitochondrial membrane that is known to suppress ferroptosis in pancreatic ductal adenocarcinoma (PDAC). Sirtuin 3 (SIRT3) is the main mitochondrial deacetylase, and we previously demonstrated that targeting SIRT3 sensitized glioblastoma to ferroptosis by promoting mitophagy and inhibiting SLC7A11. The purpose of this study was to analyze the effect of SIRT3-mediated deacetylation of mitochondrial SLC25A22 on RAS-selective lethal 3 (RSL3)-induced ferroptosis in lung adenocarcinoma (LUAD). We found that the expression of SLC25A22 and SIRT3 had a high positive correlation and that their expression was greater in LUAD tissues than in adjacent tissues. The RSL3-induced ferroptosis of LUAD led to upregulation of SLC25A22 and SIRT3, and SIRT3 protected RSL3-induced LUAD from ferroptosis in vitro and in vivo. At the molecular level, SIRT3 bound with SLC25A22 and deacetylated this protein. Targeting SIRT3 enhanced the acetylation of SLC25A22, decreased its ubiquitination, and promoted 26S proteasome degradation in LUAD cells. Therefore, our results demonstrated that SIRT3 protected LUAD cells from RSL3-induced ferroptosis, and this effect is at least partially due to its deacetylation of SLC25A22, revealing that the SIRT3-SLC25A22 axis has an important role in regulating the ferroptosis of LUAD cells.

Sirt6 loss activates Got1 and facilitates cleft palate through abnormal activating glycolysis

Cleft palate (CP) is a common congenital craniofacial malformation, which is caused by a combination of genetic and environmental factors. However, its underlying mechanism has not been elucidated. Sirtuin6 (SIRT6) mutation has been associated with craniofacial anomalies in humans. This study further defined the role of Sirt6 in palatogenesis by investigating the specific inactivation of Sirt6 in Wnt1-expressing cell lineages. Here, we demonstrated that Sirt6 conditioned knockout (Sirt6 cKO) could inhibit the osteogenesis of the palate which facilitated the occurrence of CP. Specifically, Sirt6 deficiency promoted the expression of glutamine oxaloacetic transaminase 1 (Got1) and glycolysis through deacetylation inhibition, which increased the proliferation of mouse embryonic palatal mesenchyme (MEPM) cells through the GOT1-lactate dehydrogenase A (LDHA)-transforming growth factor beta receptor 1 (TGFBR1) pathway in the early stage and inhibited the osteogenic differentiation of MEPM cells through the GOT1-LDHA-bone morphogenetic protein 2 (BMP2) pathway in the late stage. Notably, if there was a disturbance of the environment, such as retinoic acid (RA), the occurrence of CP increased. Also, the enhanced acetylation of histone 3 lysine 9 (H3K9) in Got1 induced by Sirt6 deficiency was mediated by the acetylase tat-interacting protein 60 (TIP60) rather than acetyltransferase p300 (P300). Additionally, inhibition of Got1 partially saved the promoting effect of Sirt6 cKO on the CP. Our study reveals the role of Sirt6 in facilitating CP, with Got1 as the primary driver.

Linking microRNA to metabolic reprogramming and gut microbiota in the pathogenesis of colorectal cancer (Review)

Colorectal cancer (CRC), an emerging public health concern, is one of the leading causes of cancer morbidity and mortality worldwide. An increasing body of evidence shows that dysfunction in metabolic reprogramming is a crucial characteristic of CRC progression. Specifically, metabolic reprogramming abnormalities in glucose, glutamine and lipid metabolism provide the tumour with energy and nutrients to support its rapid cell proliferation and survival. More recently, microRNAs (miRNAs) appear to be involved in the pathogenesis of CRC, including regulatory roles in energy metabolism. In addition, it has been revealed that dysbiosis in CRC might play a key role in impairing the host metabolic reprogramming processes, and while the exact interactions remain unclear, the link may lie with miRNAs. Hence, the aims of the current review include first, to delineate the metabolic reprogramming abnormalities in CRC; second, to explain how miRNAs mediate the aberrant regulations of CRC metabolic pathways; third, linking miRNAs with metabolic abnormalities and dysbiosis in CRC and finally, to discuss the roles of miRNAs as potential biomarkers.

Targeting KRAS: from metabolic regulation to cancer treatment

The Kirsten rat sarcoma viral oncogene homolog (KRAS) protein plays a key pathogenic role in oncogenesis, cancer progression, and metastasis. Numerous studies have explored the role of metabolic alterations in KRAS-driven cancers, providing a scientific rationale for targeting metabolism in cancer treatment. The development of KRAS-specific inhibitors has also garnered considerable attention, partly due to the challenge of acquired treatment resistance. Here, we review the metabolic reprogramming of glucose, glutamine, and lipids regulated by oncogenic KRAS, with an emphasis on recent insights into the relationship between changes in metabolic mechanisms driven by KRAS mutant and related advances in targeted therapy. We also focus on advances in KRAS inhibitor discovery and related treatment strategies in colorectal, pancreatic, and non-small cell lung cancer, including current clinical trials. Therefore, this review provides an overview of the current understanding of metabolic mechanisms associated with KRAS mutation and related therapeutic strategies, aiming to facilitate the understanding of current challenges in KRAS-driven cancer and to support the investigation of therapeutic strategies.

The Role of Mitochondrial Solute Carriers SLC25 in Cancer Metabolic Reprogramming: Current Insights and Future Perspectives

Cancer cells undergo remarkable metabolic changes to meet their high energetic and biosynthetic demands. The Warburg effect is the most well-characterized metabolic alteration, driving cancer cells to catabolize glucose through aerobic glycolysis to promote proliferation. Another prominent metabolic hallmark of cancer cells is their increased reliance on glutamine to replenish tricarboxylic acid (TCA) cycle intermediates essential for ATP production, aspartate and fatty acid synthesis, and maintaining redox homeostasis. In this context, mitochondria, which are primarily used to maintain energy homeostasis and support balanced biosynthesis in normal cells, become central organelles for fulfilling the heightened biosynthetic and energetic demands of proliferating cancer cells. Mitochondrial coordination and metabolite exchange with other cellular compartments are crucial. The human SLC25 mitochondrial carrier family, comprising 53 members, plays a pivotal role in transporting TCA intermediates, amino acids, vitamins, nucleotides, and cofactors across the inner mitochondrial membrane, thereby facilitating this cross-talk. Numerous studies have demonstrated that mitochondrial carriers are altered in cancer cells, actively contributing to tumorigenesis. This review comprehensively discusses the role of SLC25 carriers in cancer pathogenesis and metabolic reprogramming based on current experimental evidence. It also highlights the research gaps that need to be addressed in future studies. Understanding the involvement of these carriers in tumorigenesis may provide valuable novel targets for drug development.

Metabolic reprogramming in KRAS-mutant cancers: Proven targetable vulnerabilities and potential therapeutic strategies

Kras (Ki-ras2 Kirsten rat sarcoma viral oncogene homolog), one of the most frequently mutated oncogenes in the human genome, is considered 'untargetable'. Although specific KRASG12C inhibitors have been developed, their overall impact is limited, highlighting the need for further research on targeting KRAS-mutant cancers. Metabolic abnormalities are key hallmarks of cancer, with KRAS-driven tumors exhibiting traits like glycolysis upregulation, glutamine addiction, lipid droplet accumulation, highly active macropinocytosis, and metabolic reprogramming-associated tumor microenvironment remodeling. Targeting these unique metabolic characteristics offers a promising strategy for new cancer treatments. This review summarizes recent advances in our understanding of the metabolic network in KRAS-mutated tumor cells, discusses potential targetable vulnerabilities, and outlines clinical developments in relevant therapies, while also addressing challenges to improve strategies against these aggressive cancers.

Aspartate in tumor microenvironment and beyond: Metabolic interactions and therapeutic perspectives

Aspartate is a proteinogenic non-essential amino acid with several essential functions in proliferating cells. It is mostly produced in a cell autonomous manner from oxalacetate via glutamate oxalacetate transaminases 1 or 2 (GOT1 or GOT2), but in some cases it can also be salvaged from the microenvironment via transporters such as SLC1A3 or by macropinocytosis. In this review we provide an overview of biosynthetic pathways that produce aspartate endogenously during proliferation. We discuss conditions that favor aspartate uptake as well as possible sources of exogenous aspartate in the microenvironment of tumors and bone marrow, where most available data have been generated. We highlight metabolic fates of aspartate, its various functions, and possible approaches to target aspartate metabolism for cancer therapy.

TMSB4Y restrains sphingomyelin synthesis via de novo purine synthesis to exert a tumor suppressor function in male esophageal squamous cell carcinoma

Y chromosome genes play a vital role in sex difference of cancer. The dysregulation and functional implications of Y chromosome genes in esophageal squamous cell carcinoma (ESCC) remains elusive. Here, we analyze the Y chromosome gene signature and identify TMSB4Y as an emerging prognostic predictor in male ESCC. Functional analyses show that TMSB4Y inhibits the proliferation, invasion and metastasis of male ESCC cells. Mechanistically, we demonstrate that TMSB4Y interacts with PAICS, wherein TMSB4Y disrupts the formation of the PAICS octamer to inhibit purine de novo synthesis, leading to a decrease in the AMP/ATP ratio, subsequently impeding AMPK phosphorylation. Furthermore, we uncover a regulatory cascade orchestrated by the TMSB4Y/PAICS-AMPK axis, which exerts a suppressive effect on sphingomyelin metabolism by inhibiting the expression of sphingomyelin synthases (SMSs). Notably, Malabaricone C, an inhibitor of SMS1 and SMS2, effectively suppresses male ESCC cell proliferation and xenograft tumor growth. Collectively, these findings reveal the regulation of sphingomyelin metabolism by TMSB4Y/PAICS-AMPK axis and underscore the potential of targeting SMSs as a promising therapeutic approach for the treatment of male ESCC.

Metabolic regulation of intestinal homeostasis: molecular and cellular mechanisms and diseases

Metabolism serves not only as the organism's energy source but also yields metabolites crucial for maintaining tissue homeostasis and overall health. Intestinal stem cells (ISCs) maintain intestinal homeostasis through continuous self-renewal and differentiation divisions. The intricate relationship between metabolic pathways and intestinal homeostasis underscores their crucial interplay. Metabolic pathways have been shown to directly regulate ISC self-renewal and influence ISC fate decisions under homeostatic conditions, but the cellular and molecular mechanisms remain incompletely understood. Understanding the intricate involvement of various pathways in maintaining intestinal homeostasis holds promise for devising innovative strategies to address intestinal diseases. Here, we provide a comprehensive review of recent advances in the regulation of intestinal homeostasis. We describe the regulation of intestinal homeostasis from multiple perspectives, including the regulation of intestinal epithelial cells, the regulation of the tissue microenvironment, and the key role of nutrient metabolism. We highlight the regulation of intestinal homeostasis and ISC by nutrient metabolism. This review provides a multifaceted perspective on how intestinal homeostasis is regulated and provides ideas for intestinal diseases and repair of intestinal damage.

Glutathione Depletion and Stalwart Anticancer Activity of Metallotherapeutics Inducing Programmed Cell Death: Opening a New Window for Cancer Therapy

The cellular defense system against exogenous substances makes therapeutics inefficient as intracellular glutathione (GSH) exhibits an astounding antioxidant activity in scavenging reactive oxygen species (ROS) or reactive nitrogen species (RNS) or other free radicals produced by the therapeutics. In the cancer cell microenvironment, the intracellular GSH level becomes exceptionally high to fight against oxidative stress created by the production of ROS/RNS or any free radicals, which are the byproducts of intracellular redox reactions or cellular respiration processes. Thus, in order to maintain redox homeostasis for survival of cancer cells and their rapid proliferation, the GSH level starts to escalate. In this circumstance, the administration of anticancer therapeutics is in vain, as the elevated GSH level reduces their potential by reduction or by scavenging the ROS/RNS they produce. Therefore, in order to augment the therapeutic potential of anticancer agents against elevated GSH condition, the GSH level must be depleted by hook or by crook. Hence, this Review aims to compile precisely the role of GSH in cancer cells, the importance of its depletion for cancer therapy and examples of anticancer activity of a few selected metal complexes which are able to trigger cancer cell death by depleting the GSH level.

The effect of genetic variants of SLC22A18 on proliferation, migration, and invasion of colon cancer cells

Solute carrier family (SLC) transporters are expressed in the digestive system and play important roles in maintaining physiological functions in the body. In addition, SLC transporters act as oncoproteins or tumor-suppressor proteins during the development, progression, and metastasis of various digestive system cancers. SLC22A18, a member of the SLC22 gene family, is an orphan transporter with an unknown endogenous substrate. Previous study revealed that SLC22A18 is downregulated in colorectal cancer tissues and that it acts as a suppressor in colorectal cancer, although the effects of SLC22A18 variants on colon cancer cell proliferation, migration, and invasion are unknown. Therefore, in this study, we identified SLC22A18 variants found in multiple populations by searching public databases and determined the in vitro effects of these missense variations on transporter expression and cancer progression. Our results indicated that three missense SLC22A18 variants-p.Ala6Thr, p.Arg12Gln, and p.Arg86His-had significantly lower cell expression than the wild type, possibly owing to intracellular degradation. Furthermore, these three variants caused significantly higher proliferation, migration, and invasion of colon cancer cells than the wild type. Our findings suggest that missense variants of SLC22A18 can potentially serve as biomarkers or prognostic tools that enable clinicians to predict colorectal cancer progression.

Integrative analysis of co-expression pattern of solute carrier transporters reveals molecular subtypes associated with tumor microenvironment hallmarks and clinical outcomes in colon cancer

Recent findings have suggested that solute carrier (SLC) transporters play an important role in tumor development and progression, and alterations in the expression of individual SLC genes are critical for fulfilling the heightened metabolic requirements of cancerous cells. However, the global influence of the co-expression pattern of SLC transporters on the clinical stratification and characteristics of the tumor microenvironment (TME) remains unexplored. In this study, we identified five SLC gene subtypes based on transcriptome co-expression patterns of 187 SLC transporters by consensus clustering analysis. These subtypes, which were characterized by distinct TME and biological characteristics, were successfully employed for prognostic and chemotherapy response prediction in colon cancer patients, as well as demonstrated associations with immunotherapy benefits. Then, we generated an SLC score model comprising 113 genes to quantify SLC gene co-expression patterns and validated it as an independent prognostic factor and drug response predictor in several independent colon cancer cohorts. Patients with a high SLC score possessed distinct characteristics of copy number variation, genomic mutations, DNA methylation, and indicated an SLC-S2 subtype, which was characterized by strong stromal cell infiltration, stromal pathway activation, poor prognosis, and low predicted fluorouracil and immunotherapeutic responses. Furthermore, the analysis of the Cancer Therapeutics Response Portal database revealed that inhibitors targeting PI3K catalytic subunits could serve as promising chemosensitizing agents for individuals exhibiting high SLC scores. In conclusion, the co-expression patterns of SLC transporters aided the disease classification, and the SLC score proved to be a reliable tool for distinguishing SLC gene subtypes and guiding precise treatment in patients with colon cancer.

Cancer Therapeutic Potential and Prognostic Value of the SLC25 Mitochondrial Carrier Family: A Review

Transporters of the solute carrier family 25 (SLC25) regulate the intracellular distribution and concentration of nucleotides, amino acids, dicarboxylates, and vitamins within the mitochondrial and cytoplasmic matrices. This mechanism involves changes in mitochondrial function, regulation of cellular metabolism, and the ability to provide energy. In this review, important members of the SLC25 family and their pathways affecting tumorigenesis and progression are elucidated, highlighting the diversity and complexity of these pathways. Furthermore, the significant potential of the members of SLC25 as both cancer therapeutic targets and biomarkers will be emphasized.

A novel TNKS/USP25 inhibitor blocks the Wnt pathway to overcome multi-drug resistance in TNKS-overexpressing colorectal cancer

Modulating Tankyrases (TNKS), interactions with USP25 to promote TNKS degradation, rather than inhibiting their enzymatic activities, is emerging as an alternative/specific approach to inhibit the Wnt/β-catenin pathway. Here, we identified UAT-B, a novel neoantimycin analog isolated from Streptomyces conglobatus, as a small-molecule inhibitor of TNKS-USP25 protein-protein interaction (PPI) to overcome multi-drug resistance in colorectal cancer (CRC). The disruption of TNKS-USP25 complex formation by UAT-B led to a significant decrease in TNKS levels, triggering cell apoptosis through modulation of the Wnt/β-catenin pathway. Importantly, UAT-B successfully inhibited the CRC cells growth that harbored high TNKS levels, as demonstrated in various in vitro and in vivo studies utilizing cell line-based and patient-derived xenografts, as well as APCmin/+ spontaneous CRC models. Collectively, these findings suggest that targeting the TNKS-USP25 PPI using a small-molecule inhibitor represents a compelling therapeutic strategy for CRC treatment, and UAT-B emerges as a promising candidate for further preclinical and clinical investigations.

Mitochondrial glutamate transporter SLC25A22 uni-directionally export glutamate for metabolic rewiring in radioresistant glioblastoma

Glioblastoma Multiforme (GBM) is a malignant primary brain tumor. Radiotherapy, one of the standard treatments for GBM patients, could induce GBM radioresistance via rewiring cellular metabolism. However, the precise mechanism attributing to GBM radioresistance or targeting strategies to overcome GBM radioresistance are lacking. Here, we demonstrate that SLC25A22, a mitochondrial bi-directional glutamate transporter, is upregulated and showed uni-directionality from mitochondria to cytosol in radioresistant GBM cells, resulting in accumulating cytosolic glutamate. However, mitochondrial glutaminolysis-mediated TCA cycle metabolites and OCR are maintained constantly. The accumulated cytosolic glutamate enhances the glutathione (GSH) production and proline synthesis in radioresistant GBM cells. Increased GSH protects cells against ionizing radiation (IR)-induced reactive oxygen species (ROS) whereas increased proline, a rate-limiting substrate for collagen biosynthesis, induces extracellular matrix (ECM) remodeling, leading to GBM invasive phenotypes. Finally, we discover that genetic inhibition of SLC25A22 using miR-184 mimic decreases GBM radioresistance and aggressiveness both in vitro and in vivo. Collectively, our study suggests that SLC25A22 upregulation confers GBM radioresistance by rewiring glutamate metabolism, and SLC25A22 could be a significant therapeutic target to overcome GBM radioresistance.

Autonomous metabolic reprogramming and oxidative stress characterize endothelial dysfunction in acute myocardial infarction

Compelling evidence has accumulated on the role of oxidative stress on the endothelial cell (EC) dysfunction in acute coronary syndrome. Unveiling the underlying metabolic determinants has been hampered by the scarcity of appropriate cell models to address cell-autonomous mechanisms of EC dysfunction. We have generated endothelial cells derived from thrombectomy specimens from patients affected with acute myocardial infarction (AMI) and conducted phenotypical and metabolic characterizations. AMI-derived endothelial cells (AMIECs) display impaired growth, migration, and tubulogenesis. Metabolically, AMIECs displayed augmented ROS and glutathione intracellular content, with a diminished glucose consumption coupled to high lactate production. In AMIECs, while PFKFB3 protein levels of were downregulated, PFKFB4 levels were upregulated, suggesting a shunting of glycolysis towards the pentose phosphate pathway, supported by upregulation of G6PD. Furthermore, the glutaminolytic enzyme GLS was upregulated in AMIECs, providing an explanation for the increase in glutathione content. Finally, AMIECs displayed a significantly higher mitochondrial membrane potential than control ECs, which, together with high ROS levels, suggests a coupled mitochondrial activity. We suggest that high mitochondrial proton coupling underlies the high production of ROS, balanced by PPP- and glutaminolysis-driven synthesis of glutathione, as a primary, cell-autonomous abnormality driving EC dysfunction in AMI.

SLC25A21 downregulation promotes KRAS-mutant colorectal cancer progression by increasing glutamine anaplerosis

Emerging evidence shows that KRAS-mutant colorectal cancer (CRC) depends on glutamine (Gln) for survival and progression, indicating that targeting Gln metabolism may be a promising therapeutic strategy for KRAS-mutant CRC. However, the precise mechanism by which Gln metabolism reprogramming promotes and coordinates KRAS-mutant CRC progression remains to be fully investigated. Here, we discovered that solute carrier 25 member 21 (SLC25A21) expression was downregulated in KRAS-mutant CRC, and that SLC25A21 downregulation was correlated with poor survival of KRAS-mutant CRC patients. SLC25A21 depletion selectively accelerated the growth, invasion, migration, and metastasis of KRAS-mutant CRC cells in vitro and in vivo, and inhibited Gln-derived α-ketoglutarate (α-KG) efflux from mitochondria, thereby potentiating Gln replenishment, accompanied by increased GTP availability for persistent KRAS activation in KRAS-mutant CRC. The restoration of SLC25A21 expression impaired the KRAS-mutation-mediated resistance to cetuximab in KRAS-mutant CRC. Moreover, the arrested α-KG efflux that occurred in response to SLC25A21 depletion inhibited the activity of α-KG-dependent DNA demethylases, resulting in a further decrease in SLC25A21 expression. Our studies demonstrate that SLC25A21 plays a significant role as a tumor suppressor in KRAS-mutant CRC by antagonizing Gln-dependent anaplerosis to limit GTP availability for KRAS activation, which suggests potential alternative therapeutic strategies for KRAS-mutant CRC.

New emerging targets in osteosarcoma therapy: PTEN and PI3K/Akt crosstalk in carcinogenesis

Osteosarcoma (OS) is a malignant bone carcinoma that affects people in childhood and adulthood. The heterogeneous nature and chromosomal instability represent certain characteristics of OS cells. These cancer cells grow and migrate abnormally, making the prognosis undesirable for patients. Conventional and current treatments fail to completely eradicate tumor cells, so new therapeutics targeting genes may be considered. PI3K/Akt is a regulator of events such as growth, cell death, migration, and differentiation, and its expression changes during cancer progression. PTEN reduces PI3K/Akt expression, and its mutations and depletions have been reported in various tumors. Experimental evidence shows that there is upregulation of PI3K/Akt and downregulation of PTEN in OS. Increasing PTEN expression may suppress PI3K/Akt to minimize tumorigenesis. In addition, PI3K/Akt shows a positive association with growth, metastasis, EMT and metabolism of OS cells and inhibits apoptosis. Importantly, overexpression of PI3K/Akt causes drug resistance and radio-resistance and its level can be modulated by miRNAs, lncRNAs and circRNAs. Silencing PI3K/Akt by compounds and drugs can suppress OS. Here, we review in detail the function of the PTEN/PI3K/Akt in OS, revealing its biological function, function in tumor progression, resistance to therapy, and pharmacological significance.

The regulation of amino acid metabolism in tumor cell death: from the perspective of physiological functions

Amino acids (AAs) are crucial molecules for the synthesis of mammalian proteins as well as a source of energy and redox equilibrium maintenance. The development of tumors also requires AAs as nutrients. Increased AAs metabolism is frequently seen in tumor cells to produce enough biomass, energy, and reduction agents. However, increased AA demand may result in auxotrophy in some cancer cells, highlighting the vulnerabilities of cancers and exposing the AA metabolism as a potential target for cancer therapy. The dynamic balance of cell survival and death is required for cellular homeostasis, growth, and development. Malignant cells manage to avoid cell death through a range of mechanisms, such as developing an addiction to amino acids through metabolic adaptation. In order to offer some guidance for AA-targeted cancer therapy, we have outlined the function of AA metabolism in tumor progression, the modalities of cell death, and the regulation of AA metabolism on tumor cell death in this review.

Amino acid metabolism in health and disease

Amino acids are the building blocks of protein synthesis. They are structural elements and energy sources of cells necessary for normal cell growth, differentiation and function. Amino acid metabolism disorders have been linked with a number of pathological conditions, including metabolic diseases, cardiovascular diseases, immune diseases, and cancer. In the case of tumors, alterations in amino acid metabolism can be used not only as clinical indicators of cancer progression but also as therapeutic strategies. Since the growth and development of tumors depend on the intake of foreign amino acids, more and more studies have targeted the metabolism of tumor-related amino acids to selectively kill tumor cells. Furthermore, immune-related studies have confirmed that amino acid metabolism regulates the function of effector T cells and regulatory T cells, affecting the function of immune cells. Therefore, studying amino acid metabolism associated with disease and identifying targets in amino acid metabolic pathways may be helpful for disease treatment. This article mainly focuses on the research of amino acid metabolism in tumor-oriented diseases, and reviews the research and clinical research progress of metabolic diseases, cardiovascular diseases and immune-related diseases related to amino acid metabolism, in order to provide theoretical basis for targeted therapy of amino acid metabolism.

Targeting of SLC25A22 boosts the immunotherapeutic response in KRAS-mutant colorectal cancer

KRAS is an important tumor intrinsic factor driving immune suppression in colorectal cancer (CRC). In this study, we demonstrate that SLC25A22 underlies mutant KRAS-induced immune suppression in CRC. In immunocompetent male mice and humanized male mice models, SLC25A22 knockout inhibits KRAS-mutant CRC tumor growth with reduced myeloid derived suppressor cells (MDSC) but increased CD8+ T-cells, implying the reversion of mutant KRAS-driven immunosuppression. Mechanistically, we find that SLC25A22 plays a central role in promoting asparagine, which binds and activates SRC phosphorylation. Asparagine-mediated SRC promotes ERK/ETS2 signaling, which drives CXCL1 transcription. Secreted CXCL1 functions as a chemoattractant for MDSC via CXCR2, leading to an immunosuppressive microenvironment. Targeting SLC25A22 or asparagine impairs KRAS-induced MDSC infiltration in CRC. Finally, we demonstrate that the targeting of SLC25A22 in combination with anti-PD1 therapy synergizes to inhibit MDSC and activate CD8+ T cells to suppress KRAS-mutant CRC growth in vivo. We thus identify a metabolic pathway that drives immunosuppression in KRAS-mutant CRC.

SLC25A22 as a Key Mitochondrial Transporter Against Ferroptosis by Producing Glutathione and Monounsaturated Fatty Acids

Aims: Ferroptosis, a type of oxidative cell death driven by unlimited lipid peroxidation, is emerging as a target for cancer therapy. Although mitochondrial dysfunction may lead to ferroptosis, the underlying molecular mechanisms and metabolic pathways for ferroptosis are incompletely understood. Here, we identify solute carrier family 25 member 22 (SLC25A22), a mitochondrial glutamate transporter, as a driver of ferroptosis resistance in pancreatic ductal adenocarcinoma (PDAC) cells. Results: The downregulation of SLC25A22 expression was associated with increased sensitivity to ferroptosis, but not to apoptosis. Mechanistically, on the one hand, SLC25A22-dependent NAPDH synthesis blocks ferroptotic cell death in PDAC cells through mediating the production of glutathione (GSH), the most important hydrophilic antioxidant. On the other hand, SLC25A22 promotes the expression of stearoyl-CoA desaturase in PDAC cells in an AMP-activated protein kinase-dependent manner, resulting in the production of antiferroptotic monounsaturated fatty acids (MUFAs). The animal study further confirms that SLC25A22 inhibits ferroptosis-mediated tumor suppression. Innovation: SLC25A22 is a novel metabolic repressor of ferroptosis by producing GSH and MUFAs. Conclusion: These findings establish a previously unrecognized metabolic defense pathway to limit ferroptotic cell death in vitro and in vivo. Antioxid. Redox Signal. 39, 166-185.

Identification of Some Glutamic Acid Derivatives with Biological Potential by Computational Methods

Glutamic acid is a non-essential amino acid involved in multiple metabolic pathways. Of high importance is its relationship with glutamine, an essential fuel for cancer cell development. Compounds that can modify glutamine or glutamic acid behaviour in cancer cells have resulted in attractive anticancer therapeutic alternatives. Based on this idea, we theoretically formulated 123 glutamic acid derivatives using Biovia Draw. Suitable candidates for our research were selected among them. For this, online platforms and programs were used to describe specific properties and their behaviour in the human organism. Nine compounds proved to have suitable or easy to optimise properties. The selected compounds showed cytotoxicity against breast adenocarcinoma, lung cancer cell lines, colon carcinoma, and T cells from acute leukaemia. Compound 2Ba5 exhibited the lowest toxicity, and derivative 4Db6 exhibited the most intense bioactivity. Molecular docking studies were also performed. The binding site of the 4Db6 compound in the glutamine synthetase structure was determined, with the D subunit and cluster 1 being the most promising. In conclusion, glutamic acid is an amino acid that can be manipulated very easily. Therefore, molecules derived from its structure have great potential to become innovative drugs, and further research on these will be conducted.

Single-cell metabolic fingerprints discover a cluster of circulating tumor cells with distinct metastatic potential

Circulating tumor cells (CTCs) are recognized as direct seeds of metastasis. However, CTC count may not be the "best" indicator of metastatic risk because their heterogeneity is generally neglected. In this study, we develop a molecular typing system to predict colorectal cancer metastasis potential based on the metabolic fingerprints of single CTCs. After identification of the metabolites potentially related to metastasis using mass spectrometry-based untargeted metabolomics, setup of a home-built single-cell quantitative mass spectrometric platform for target metabolite analysis in individual CTCs and use of a machine learning method composed of non-negative matrix factorization and logistic regression, CTCs are divided into two subgroups, C1 and C2, based on a 4-metabolite fingerprint. Both in vitro and in vivo experiments demonstrate that CTC count in C2 subgroup is closely associated with metastasis incidence. This is an interesting report on the presence of a specific population of CTCs with distinct metastatic potential at the single-cell metabolite level.

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.

Glutathione-responsive and -exhausting metal nanomedicines for robust synergistic cancer therapy

Due to their rapid and uncontrolled proliferation, cancer cells are characterized by overexpression of glutathione (GSH), which impairs reactive oxygen species (ROS)-based therapy and weakens the chemotherapeutic agent-induced toxification. Extensive efforts have been made in the past few years to improve therapeutic outcomes by depleting intracellular GSH. Special focus has been given to the anticancer applications of varieties of metal nanomedicines with GSH responsiveness and exhaustion capacity. In this review, we introduce several GSH-responsive and -exhausting metal nanomedicines that can specifically ablate tumors based on the high concentration of intracellular GSH in cancer cells. These include inorganic nanomaterials, metal-organic frameworks (MOFs), and platinum-based nanomaterials. We then discuss in detail the metal nanomedicines that have been extensively applied in synergistic cancer therapy, including chemotherapy, photodynamic therapy (PDT), sonodynamic therapy (SDT), chemodynamic therapy (CDT), ferroptotic therapy, and radiotherapy. Finally, we present the horizons and challenges in the field for future development.

Nutrient transporters: connecting cancer metabolism to therapeutic opportunities

Cancer cells rely on certain extracellular nutrients to sustain their metabolism and growth. Solute carrier (SLC) transporters enable cells to acquire extracellular nutrients or shuttle intracellular nutrients across organelles. However, the function of many SLC transporters in cancer is unknown. Determining the key SLC transporters promoting cancer growth could reveal important therapeutic opportunities. Here we summarize recent findings and knowledge gaps on SLC transporters in cancer. We highlight existing inhibitors for studying these transporters, clinical trials on treating cancer by blocking transporters, and compensatory transporters used by cancer cells to evade treatment. We propose targeting transporters simultaneously or in combination with targeted therapy or immunotherapy as alternative strategies for effective cancer therapy.

Cancer-associated fibroblasts potentiate colorectal cancer progression by crosstalk of the IGF2-IGF1R and Hippo-YAP1 signaling pathways

Colorectal cancer (CRC) is one of the most common cancers worldwide. The tumor microenvironment exerts crucial effects in driving CRC progression. Cancer-associated fibroblasts (CAFs) serve as one of the most important tumor microenvironment components promoting CRC progression. This study aimed to elucidate the novel molecular mechanisms of CAF-secreted insulin-like growth factor (IGF) 2 in colorectal carcinogenesis. Our results indicated that IGF2 was a prominent factor upregulated in CAFs compared with normal fibroblasts. CAF-derived conditioned media (CM) promoted tumor growth, migration, and invasion of HCT 116 and DLD-1 cells. IGF1R expression is significantly increased in CRC, serving as a potent receptor in response to IGF2 stimulation and predicting unfavorable outcomes for CRC patients. Apart from the PI3K-AKT pathway, RNA-seq analysis revealed that the YAP1-target signature serves as a prominent downstream effector to mediate the oncogenic signaling of IGF2-IGF1R. By single-cell RNA sequencing (scRNA-seq) and immunohistochemical validation, IGF2 was found to be predominantly secreted by CAFs, whereas IGF1R was expressed mainly by cancer cells. IGF2 triggers the nuclear accumulation of YAP1 and upregulates YAP1 target signatures; however, these effects were abolished by either IGF1R knockdown or inhibition with picropodophyllin (PPP), an IGF1R inhibitor. Using CRC organoid and in vivo studies, we found that cotargeting IGF1R and YAP1 with PPP and verteporfin (VP), a YAP1 inhibitor, enhanced antitumor effects compared with PPP treatment alone. In conclusion, this study revealed a novel molecular mechanism by which CAFs promote CRC progression. The findings highlight the translational potential of the IGF2-IGF1R-YAP1 axis as a prognostic biomarker and therapeutic target for CRC. © 2022 The Pathological Society of Great Britain and Ireland.

Role of Mitochondrial Transporters on Metabolic Rewiring of Pancreatic Adenocarcinoma: A Comprehensive Review

Pancreatic cancer is among the deadliest cancers worldwide and commonly presents as pancreatic ductal adenocarcinoma (PDAC). Metabolic reprogramming is a hallmark of PDAC. Glucose and glutamine metabolism are extensively rewired in order to fulfil both energetic and synthetic demands of this aggressive tumour and maintain favorable redox homeostasis. The mitochondrial pyruvate carrier (MPC), the glutamine carrier (SLC1A5_Var), the glutamate carrier (GC), the aspartate/glutamate carrier (AGC), and the uncoupling protein 2 (UCP2) have all been shown to influence PDAC cell growth and progression. The expression of MPC is downregulated in PDAC and its overexpression reduces cell growth rate, whereas the other four transporters are usually overexpressed and the loss of one or more of them renders PDAC cells unable to grow and proliferate by altering the levels of crucial metabolites such as aspartate. The aim of this review is to comprehensively evaluate the current experimental evidence about the function of these carriers in PDAC metabolic rewiring. Dissecting the precise role of these transporters in the context of the tumour microenvironment is necessary for targeted drug development.

The sodium channel subunit SCNN1B suppresses colorectal cancer via suppression of active c-Raf and MAPK signaling cascade

The incidence of colorectal cancer (CRC) is rising worldwide. Here, we identified SCNN1B as an outlier down-regulated in CRC and it functions as a tumor suppressor. SCNN1B mRNA and protein expression were down-regulated in primary CRC and CRC cells. In a tissue microarray cohort (N = 153), SCNN1B protein was an independent prognostic factor for favorable outcomes in CRC. Ectopic expression of SCNN1B in CRC cell lines suppressed cell proliferation, induced apoptosis, and cell cycle arrest, and suppressed cell migration in vitro. Xenograft models validated tumor suppressive function of SCNN1B in vivo. Mechanistically, Gene Set Enrichment Analysis (GSEA) showed that SCNN1B correlates with KRAS signaling. Consistently, MAPK qPCR and kinase arrays revealed that SCNN1B suppressed MAPK signaling. In particular, SCNN1B overexpression suppressed p-MEK/p-ERK expression and SRE-mediated transcription activities, confirming blockade of Ras-Raf-MEK-ERK cascade. Mechanistically, SCNN1B did not affect KRAS activation, instead impairing activation of c-Raf by inducing its inhibitory phosphorylation and targeting active c-Raf for degradation. The ectopic expression of c-Raf fully rescued cell proliferation and colony formation in SCNN1B-overexpressing CRC cells, confirming c-Raf as the principal molecular target of SCNN1B. In summary, we identified SCNN1B as a tumor suppressor by functioning as a c-Raf antagonist, which in turn suppressed oncogenic MEK-ERK signaling.

Interaction between glycolysis‒cholesterol synthesis axis and tumor microenvironment reveal that gamma-glutamyl hydrolase suppresses glycolysis in colon cancer

Background

Metabolic reprogramming is a feature of cancer. However, colon cancer subtypes based on the glycolysis‒cholesterol synthesis axis have not been identified, and little is known about connections between metabolic features and the tumor microenvironment.

Methods

Data for 430 colon cancer cases were extracted from The Cancer Genome Atlas, including transcriptome data, clinical information, and survival outcomes. Glycolysis and cholesterol synthesis-related gene sets were obtained from the Molecular Signatures Database for a gene set variation analysis. The relationship between the genomic landscape and immune landscape were investigated among four metabolic subtypes. Hub genes were determined. The clinical significance of candidate hub gene was evaluated in 264 clinical samples and potential functions were validated in vitro and in vivo.

Results

Colon cancer cases were clustered into four metabolic subtypes: quiescent, glycolytic, cholesterogenic, and mixed. The metabolic subtypes differed with respect to the immune score, stromal score, and estimate score using the ESTIMATE algorithm, cancer-immunity cycle, immunomodulator signatures, and signatures of immunotherapy responses. Patients in the cholesterogenic group had better survival outcomes than those for other subtypes, especially glycolytic. The glycolytic subtype was related to unfavorable clinical characteristics, including high mutation rates in TTN, APC, and TP53, high mutation burden, vascular invasion, right colon cancer, and low-frequency microsatellite instability. GGH, CACNG4, MME, SLC30A2, CKMT2, SYN3, and SLC22A31 were identified as differentially expressed both in glycolytic-cholesterogenic subgroups as well as between colon cancers and healthy samples, and were involved in glycolysis‒cholesterol synthesis. GGH was upregulated in colon cancer; its high expression was correlated with CD4⁺ T cell infiltration and longer overall survival and it was identified as a favorable independent prognostic factor. The overexpression of GGH in colon cancer-derived cell lines (SW48 and SW480) inhibited PKM, GLUT1, and LDHA expression and decreased the extracellular lactate content and intracellular ATP level. The opposite effects were obtained by GGH silencing. The phenotype associated with GGH was also validated in a xenograft nude mouse model.

Conclusions

Our results provide insight into the connection between metabolism and the tumor microenvironment in colon cancer and provides preliminary evidence for the role of GGH, providing a basis for subsequent studies.

Glutathione peroxidase 2 overexpression promotes malignant progression and cisplatin resistance of KRAS‑mutated lung cancer cells

Kirsten rat sarcoma viral oncogene homolog (KRAS) aberrations frequently occur in patients with lung cancer. Oncogenic KRAS is characterized by excessive reactive oxygen species (ROS) accumulation, thus, ROS detoxification may contribute to KRAS‑driven lung tumorigenesis. In the present study, the influence of glutathione peroxidase 2 (GPX2) on malignant progression and cisplatin resistance of KRAS‑driven lung cancer was explored. The RNA sequencing data from TCGA lung cancer samples and GEO database were downloaded and analyzed. The effects of GPX2 on KRAS‑driven lung tumorigenesis were evaluated by western blotting, cell viability assay, soft agar assay, Transwell assay, tumor xenograft model, flow cytometry, BrdU incorporation assay, transcriptome RNA sequencing, luciferase reporter assay and RNA immunoprecipitation. In the present study, GPX2 was upregulated in patients with non‑small cell lung carcinoma (NSCLC), and positively correlated with poor overall survival. Ectopic GPX2 expression facilitated malignant progression of KRASG12C‑transformed BEAS‑2B cells. Moreover, GPX2 overexpression promoted growth, migration, invasion, tumor xenograft growth and cisplatin resistance of KRAS‑mutated NSCLC cells, while GPX2 knockdown exhibited the opposite effects. GPX2 overexpression reduced ROS accumulation and increased matrix metalloproteinase‑1 (MMP1) expression in KRAS‑mutated NSCLC cells. In addition, GPX2 was directly targeted by miR‑325‑3p, while MMP1 knockdown or miR‑325‑3p overexpression partially abrogated the effects of GPX2 in NSCLC cells. In conclusion, the results indicated that GPX2 facilitated malignant progression and cisplatin resistance of KRAS‑driven lung cancer, and inhibition of GPX2 may be a feasible strategy for lung cancer treatment, particularly in patients with active KRAS mutations.

Rerouting the drug response: Overcoming metabolic adaptation in KRAS-mutant cancers

Mutations in guanosine triphosphatase KRAS are common in lung, colorectal, and pancreatic cancers. The constitutive activity of mutant KRAS and its downstream signaling pathways induces metabolic rewiring in tumor cells that can promote resistance to existing therapeutics. In this review, we discuss the metabolic pathways that are altered in response to treatment and those that can, in turn, alter treatment efficacy, as well as the role of metabolism in the tumor microenvironment (TME) in dictating the therapeutic response in KRAS-driven cancers. We highlight metabolic targets that may provide clinical opportunities to overcome therapeutic resistance and improve survival in patients with these aggressive cancers.

Interplay between the m6A Epitranscriptome and Tumor Metabolism: Mechanisms and Therapeutic Implications

N⁶-methyladenosine (m⁶A) modification of messenger RNA (mRNA) influences the stability and translation of the transcripts into functional proteins. Recent studies reveal the role of m⁶A modifications in regulating the metabolism of basic biomolecules such as glucose, lipids and amino acids. Such mechanisms are not only important for physiological functions of normal cells but also prove to be pivotal for the pathogenesis of cancers by driving dysregulated metabolism. M⁶A writers, readers and erasers function co-operatively to promote aberrant glucose, lipid and amino acid metabolism in cancer cells, which in turn support increased proliferative and metastatic potential. Better understanding of the relationship between m⁶A and metabolism in malignancy may unravel novel therapeutic targets as well as biomarkers in cancer. In this review, we summarize the recent evidence demonstrating the interplay between m⁶A modification and cancer metabolism and their therapeutic implications.

Metabolism-Based Molecular Subtyping Endows Effective Ketogenic Therapy in p53-Mutant Colon Cancer

Although targeting cancer metabolism is a promising therapeutic strategy, clinical success depends on accurate molecular and metabolic subtyping. Here, this study reports two metabolism-based molecular subtypes associated with the ketogenic treatment of colon cancer: glycolytic (glycolysis+ /ketolysis- ) and ketolytic (glycolysis+ /ketolysis+ ), which are manifested by distinct profiles of metabolic enzymes and mitochondrial dysfunction, and by different responses to ketone-containing interventions in vitro and in vivo. Notably, the glycolytic subtype is able to be transformed into the ketolytic subtype in p53-mutated tumors upon glucose limitation, rendering resistance to ketogenic therapy associated with upregulation of ketolytic enzymes, such as OXCT1 by mutant p53. The allosteric activator of mutant p53 effectively blocks the rewired molecular expression and the reprogrammed metabolism, leading to the suppression of tumor growth. The findings highlight the utility of metabolic subtyping to guide ketogenic therapy in colon cancer and identify mutant p53 as a synthetic lethality target for ketogenic treatment.

Asparagine, colorectal cancer, and the role of sex, genes, microbes, and diet: A narrative review

Asparagine (Asn) and enzymes that catalyze the metabolism of Asn have been linked to the regulation and propagation of colorectal cancer (CRC). Increased Asn and asparagine synthetase (ASNS) expression, both contribute to CRC progression and metastasis. In contradistinction, L-asparaginase (ASNase) which breaks down Asn, exhibits an anti-tumor effect. Metabolic pathways such as KRAS/PI3K/AKT/mTORC1 signaling and high SOX12 expression can positively regulate endogenous Asn production. Conversely, the tumor suppressor, TP53, negatively impacts ASNS, thus limiting Asn synthesis and reducing tumor burden. Asn abundance can be altered by factors extrinsic to the cancer cell such as diet, the microbiome, and therapeutic use of ASNase. Recent studies have shown that sex-related factors can also influence the regulation of Asn, and high Asn production results in poorer prognosis for female CRC patients but not males. In this narrative review, we critically review studies that have examined endogenous and exogenous modulators of Asn bioavailability and summarize the key metabolic networks that regulate Asn metabolism. We also provide new hypotheses regarding sex-related influences on Asn, including the involvement of the sex-steroid hormone estrogen and estrogen receptors. Further, we hypothesize that sex-specific factors that influence Asn metabolism can influence clinical outcomes in CRC patients.

Analysis of the Prognostic Significance and Immune Infiltration of the Amino Acid Metabolism-Related Genes in Colon Adenocarcinoma

Amino acid metabolization is verified to be a part in the progression of cancer. However, genes related to the amino acid metabolism have not been identified in colon adenocarcinoma (COAD). A systematic prognostic model of COAD becomes a pressing need. Among genes related to the amino acid metabolism, RIMKLB, ASPG, TH, MTAP, AZIN2, PSMB2, HDC, ACMSD, and PSMA8 were identified to construct a risk model. Kaplan–Meier (K–M) analyses demonstrated that the high-risk group achieved a poor prognosis. Area under the respective ROC (AUC) values indicated the robustness of the model. To highlight its clinical value, multivariate Cox was used to obtain the optimal variables to construct a nomogram. A higher tumor mutation burden was observed in the high-risk group. However, the low-risk group had a stronger immune infiltration. Seven molecular subtypes were found by consensus cluster. Twenty-two hub genes were identified related to the ESTIMATE score using WGCNA. In brief, our research constructed a stable prognostic model related to the amino acid metabolism in COAD, revealing its connection to the immune microenvironment. The model guided the outcome of COAD and the direction of immunotherapy.

The cholesterol uptake regulator PCSK9 promotes and is a therapeutic target in APC/KRAS-mutant colorectal cancer

Therapeutic targeting of KRAS-mutant colorectal cancer (CRC) is an unmet need. Here, we show that Proprotein Convertase Subtilisin/Kexin type 9 (PSCK9) promotes APC/KRAS-mutant CRC and is a therapeutic target. Using CRC patient cohorts, isogenic cell lines and transgenic mice, we identify that de novo cholesterol biosynthesis is induced in APC/KRAS mutant CRC, accompanied by increased geranylgeranyl diphosphate (GGPP)─a metabolite necessary for KRAS activation. PCSK9 is the top up-regulated cholesterol-related gene. PCSK9 depletion represses APC/KRAS-mutant CRC cell growth in vitro and in vivo, whereas PCSK9 overexpression induces oncogenesis. Mechanistically, PCSK9 reduces cholesterol uptake but induces cholesterol de novo biosynthesis and GGPP accumulation. GGPP is a pivotal metabolite downstream of PCSK9 by activating KRAS/MEK/ERK signaling. PCSK9 inhibitors suppress growth of APC/KRAS-mutant CRC cells, organoids and xenografts, especially in combination with simvastatin. PCSK9 overexpression predicts poor survival of APC/KRAS-mutant CRC patients. Together, cholesterol homeostasis regulator PCSK9 promotes APC/KRAS-mutant CRC via GGPP-KRAS/MEK/ERK axis and is a therapeutic target.

A Biscuit Containing Fucoxanthin Prevents Colorectal Carcinogenesis in Mice

Fucoxanthin (Fx) is a critical pigment required for photosynthesis in brown algae and microalgae. Fx is also a dietary marine carotenoid that with potent anticancer activity in vitro and in vivo. Some popular light meals for increased satiety, such as biscuits, cereals, and crackers, are frequently fortified with micronutrients for human health benefits. However, data on the anticancer potential of Fx-supplemented light meals in humans and animal models remain limited. In the present study, we investigated the anticancer effects of a Fx-supplemented biscuit using a carcinogenic murine azoxymethane/dextran sodium sulfate (AOM/DSS) model. We observed that periodic administration of biscuits containing 0.3% Fx (Fx-biscuit) at an interval of 3 days (each 15 h) per week for 15 weeks significantly inhibited colorectal carcinogenesis in AOM/DSS mice. Comprehensive gene analysis demonstrated that the Fx-biscuit significantly altered the expression of 138 genes in the colorectal mucosal tissue of the mice. In particular, the expression of heat shock protein 70 (HSP70) genes, Hspa1b (-35.7-fold) and Hspa1a (-34.9-fold), was markedly downregulated. HSP70 is a polyfunctional chaperone protein that is involved in cancer development. Compared to the control-biscuit group, the number of cells with markedly high fluorescence for HSP70 protein (HSP70^high) in colorectal mucosal crypts and adenocarcinomas significantly reduced by 0.3- and 0.2-fold, respectively, in the Fx-biscuit group. Our results suggested that Fx-biscuit possesses chemopreventive potential in the colorectal cancer of AOM/DSS mice via the downregulation of HSP70.

The Overexpression of SLC25A13 Predicts Poor Prognosis and Is Correlated with Immune Cell Infiltration in Patients with Skin Cutaneous Melanoma

Purpose

Skin cutaneous melanoma (SKCM) is one of the most malignant and aggressive cancers with poor prognosis due to its rapid progression towards metastasis. Thus, finding clinically relevant biomarkers for early diagnosis, prognosis, and therapy prediction is essential. This study focused on the identification of SLC25A13 as a novel biomarker for SKCM and is aimed at investigating the biological functions of solute carrier family 25 member 13 (SLC25A13) in the development of SKCM.

Methods

GEPIA was used to analyze the diagnostic and prognostic values of SLC25A13 in SKCM using the TCGA dataset. PrognoScan was used to validate the prognostic value of SLC25A13 and its coexpressed genes in SKCM. TISIDB was established to reveal the relationship between the expression of SLC25A13 and immune infiltration in SKCM. The protein expression of SLC25A13 in SKCM was evaluated by the Human Protein Atlas. The signaling pathways and biological functions of SLC25A13 in SKCM were analyzed by LinkOmics. Metascape was applied to analyze the functional enrichment analysis of SLC25A13. Protein-protein interaction analysis of SLC25A13 was performed by GeneMANIA.

Results

The mRNA and protein levels of SLC25A13 in the SKCM were much higher than those in the normal tissue. Furthermore, the overexpression of SLC25A13 predicts worse outcomes of SKCM patients. Moreover, the SLC25A13 expression was negatively correlated with the immune infiltration level of SKCM. The overexpression of SLC25A13 coexpressed genes, such as ACLY and AFG3L2, and SCL25A13 interacting genes also predicted the unfavorable prognosis of SKCM patients. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of SLC25A13 coexpressed genes showed that these genes are enriched in ATPase activity, cell cycle, mTOR, and VEGFA-VEGFR2 signaling pathways, which were relevant to tumor development and angiogenesis. Gene set enrichment analysis (GSEA) demonstrated that the SLC25A13 expression was related to infiltrating immune cells in SKCM.

Conclusion

Our findings revealed that SLC25A13 might be a potential prognostic and therapeutic biomarker for SKCM.

Targeting cellular energy metabolism- mediated ferroptosis by small molecule compounds for colorectal cancer therapy

Alterations in cellular energy metabolism, including glycolysis, glutamine and lipid metabolism that affects ferroptosis in the tumour microenvironment (TME), play a critical role in the development and progression of colorectal cancer (CRC) and offer evolutionary advantages to tumour cells and even enhance their aggressive phenotype. This review summarises the findings on the dysregulated energy metabolism pathways, including lipid and fatty acid metabolism especially for regulating the ferroptosis in TME. Moreover, the cellular energy metabolism and tumour ferroptosis to be regulated by small molecule compounds, which targeting the different aspects of metabolic pathways of energy production as well as metabolic enzymes that connect with the tumour cell growth and ferroptosis in CRC are also discussed. In this review, we will provide a comprehensive summary on small molecule compounds regulatory function of different energy metabolic routes on ferroptosis in tumour cells and discuss those metabolic vulnerabilities for the development of potential ferroptosis-based tumour therapies for colorectal cancer.

Glutamic oxaloacetic transaminase 1 as a potential target in human cancer

Glutamic Oxaloacetic Transaminase 1 (GOT1) is one distinct isoenzyme of glutamic oxaloacetic transaminase in eukaryotic cells, which is located in the cytoplasm. To date, several studies have shown that GOT1 plays a critical role in regulating cell proliferation by participating in amino acid metabolism, especially in glutamine metabolism. In addition, GOT1 is overexpressed in many cancer, so GOT1 has been identified as a potentially therapeutic target. Herein, this review summarizes the structure and function of GOT1 and the important roles of GOT1 in some tumor progress, as well as the characterization of GOT1 inhibitors. It may provide new insight into the discovery of small compounds as potential anti-GOT1 drugs for treatment of cancer.

Asparagine Metabolism in Tumors Is Linked to Poor Survival in Females with Colorectal Cancer: A Cohort Study

The interplay between the sex-specific differences in tumor metabolome and colorectal cancer (CRC) prognosis has never been studied and represents an opportunity to improve patient outcomes. This study examines the link between tumor metabolome and prognosis by sex for CRC patients. Using untargeted metabolomics analysis, abundances of 91 metabolites were obtained from primary tumor tissues from 197 patients (N = 95 females, N = 102 males) after surgical colectomy for stage I-III CRC. Cox Proportional hazard (PH) regression models estimated the associations between tumor metabolome and 5-year overall survival (OS) and recurrence-free survival (RFS), and their interactions with sex. Eleven metabolites had significant sex differences in their associations with 5-year OS, and five metabolites for 5-year RFS. The metabolites asparagine and serine had sex interactions for both OS and RFS. Furthermore, in the asparagine synthetase (ASNS)-catalyzed asparagine synthesis pathway, asparagine was associated with substantially poorer OS (HR (95% CI): 6.39 (1.78–22.91)) and RFS (HR (95% CI): 4.36 (1.39–13.68)) for female patients only. Similar prognostic disadvantages in females were seen in lysophospholipid and polyamine synthesis. Unique metabolite profiles indicated that increased asparagine synthesis was associated with poorer prognosis for females only, providing insight into precision medicine for CRC treatment stratified by sex.

Extracellular Vesicles Derived-LAT1 mRNA as a Powerful Inducer of Colorectal Cancer Aggressive Phenotype

Colorectal cancer (CRC) is the third most common cancer in the world and represents the third most deadly tumor worldwide. About 15–25% of patients present metastasis in the moment of diagnosis, the liver being the most common site of metastization. Therefore, the development of new therapeutic agents is needed, to improve the patients’ prognosis. Amino acids transporters, LAT1 and ASCT2, are described as upregulated in CRC, being associated with a poor prognosis. Extracellular vesicles have emerged as key players in cell-to-cell communication due to their ability to transfer biomolecules between cells, with a phenotypic impact on the recipient cells. Thus, this study analyzes the presence of LAT1 and ASCT2 mRNAs in CRC-EVs and evaluates their role in phenotype modulation in a panel of four recipient cell lines (HCA-7, HEPG-2, SK-HEP-1, HKC-8). We found that HCT 116-EVs carry LAT1, ASCT2 and other oncogenic mRNAs being taken up by recipient cells. Moreover, the HCT 116-EVs’ internalization was associated with the increase of LAT1 mRNA in SK-HEP-1 cells. We also observed that HCT 116-EVs induce a higher cell migration capacity and proliferation of SK-HEP-1 and HKC-8 cells. The present study supports the LAT1-EVs’ mRNA involvement in cell phenotype modulation, conferring advantages in cell migration and proliferation.

Glutamine-Derived Aspartate Biosynthesis in Cancer Cells: Role of Mitochondrial Transporters and New Therapeutic Perspectives

Simple Summary

In recent years, aspartate has been increasingly acknowledged as a critical player in the metabolism of cancer cells which use this metabolite for nucleotide and protein synthesis and for redox homeostasis. Most intracellular aspartate derives from the mitochondrial catabolism of glutamine. To date at least four mitochondrial transporters have been involved in this metabolic pathway. Their involvement appears to be cancer type-specific and dependent on glutamine availability. Targeting these mitochondrial transporters may represent a new attractive strategy to fight cancer. The aim of this review is to dissect the role of each of these transporters in relation to the type of cancer and the availability of nutrients in the tumoral microenvironment.

Abstract

Aspartate has a central role in cancer cell metabolism. Aspartate cytosolic availability is crucial for protein and nucleotide biosynthesis as well as for redox homeostasis. Since tumor cells display poor aspartate uptake from the external environment, most of the cellular pool of aspartate derives from mitochondrial catabolism of glutamine. At least four transporters are involved in this metabolic pathway: the glutamine (SLC1A5_var), the aspartate/glutamate (AGC), the aspartate/phosphate (uncoupling protein 2, UCP2), and the glutamate (GC) carriers, the last three belonging to the mitochondrial carrier family (MCF). The loss of one of these transporters causes a paucity of cytosolic aspartate and an arrest of cell proliferation in many different cancer types. The aim of this review is to clarify why different cancers have varying dependencies on metabolite transporters to support cytosolic glutamine-derived aspartate availability. Dissecting the precise metabolic routes that glutamine undergoes in specific tumor types is of upmost importance as it promises to unveil the best metabolic target for therapeutic intervention.

The Crosstalk Between Signaling Pathways and Cancer Metabolism in Colorectal Cancer

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide. Metabolic reprogramming represents an important cancer hallmark in CRC. Reprogramming core metabolic pathways in cancer cells, such as glycolysis, glutaminolysis, oxidative phosphorylation, and lipid metabolism, is essential to increase energy production and biosynthesis of precursors required to support tumor initiation and progression. Accumulating evidence demonstrates that activation of oncogenes and loss of tumor suppressor genes regulate metabolic reprogramming through the downstream signaling pathways. Protein kinases, such as AKT and c-MYC, are the integral components that facilitate the crosstalk between signaling pathways and metabolic pathways in CRC. This review provides an insight into the crosstalk between signaling pathways and metabolic reprogramming in CRC. Targeting CRC metabolism could open a new avenue for developing CRC therapy by discovering metabolic inhibitors and repurposing protein kinase inhibitors/monoclonal antibodies.

SLC25A21 Suppresses Cell Growth in Bladder Cancer via an Oxidative Stress-Mediated Mechanism

Background

Bladder cancer (BCa) is a commonly diagnosed malignancy worldwide that has poor survival depending on its intrinsic biologic aggressiveness and a peculiar radio- and chemoresistance features. Gaining a better understanding of tumorigenesis and developing new diagnosis and treatment strategies for BCa is important for improving BCa clinical outcome. SLC25 family member 21 (SLC25A21), a carrier transporting C5-C7 oxodicarboxylates, has been reported to contribute to oxoadipate acidemia. However, the potential role of SLC25A21 in cancer remains absolutely unknown.

Methods

The expression levels of SLC25A21 in BCa and normal tissues were examined by real-time PCR and immunohistochemistry. Gain-of- and loss-of-function experiments were performed to detect the biological functions of SLC25A21 in vitro and in vivo by CCK-8 assay, plate colony formation assay, cell migration, invasion assay and experimental animal models. The subcellular distribution of substrate mediated by SLC25A21, mitochondrial membrane potential and ROS production were assessed to explore the potential mechanism of SLC25A21 in BCa.

Results

We found that the expression of SLC25A21 was downregulated in BCa tissues compared to normal tissues. A significant positive correlation between decreased SLC25A21 expression and poor prognosis was observed in BCa patients. Overexpression of SLC25A21 significantly inhibited cell proliferation, migration and invasion and induced apoptosis in vitro. Moreover, the enhanced SLC25A21 expression significantly suppressed tumor growth in a xenograft mouse model. Furthermore, we revealed that SLC25A21 suppressed BCa growth by inducing the efflux of mitochondrial α-KG to the cytosol, decreasing to against oxidative stress, and activating the ROS-mediated mitochondrion-dependent apoptosis pathway.

Conclusions

Our findings provide the first link between SLC25A21 expression and BCa and demonstrate that SLC25A21 acts as a crucial suppressor in BCa progression, which may help to provide new targets for BCa intervention.

Identification of prognostic long intergenic non-coding RNAs as competing endogenous RNAs with KRAS mutations in colorectal cancer

Colorectal cancer (CRC) is recognized as a common type of human cancer, and KRAS mutations are correlated with poor CRC survival outcomes. The evaluation and prediction of CRC results remain challenging. In the present study, RNA sequencing and clinical data from The Cancer Genome Atlas were used to identify KRAS mutation-related prognostic long intergenic non-coding RNAs (lincRNAs) in CRC. Significantly dysregulated lincRNAs and independent prognostic lincRNAs with KRAS mutations in CRC were identified. Two lincRNAs with KRAS mutations, LINC00265 and AL390719.2, were selected as key prognostic lincRNAs for both 10- and 5-year survival rates. In addition, competing endogenous (ce)RNA models were constructed to comprehensively assess the oncogenic performance of the two key lincRNAs. The ceRNA models suggested that LINC00265 and AL390719.2 are critical for the cell cycle and cancer pathways. Finally, reverse transcription-quantitative PCR was used to validate the ceRNA models in 12 pairs of CRC tissue samples. These prognostic lincRNAs may provide novel biomarkers for the prognostic prediction of CRC. The ceRNA model may also demonstrate the underlying mechanism of these lincRNAs in CRC.