Metformin Reprograms Tryptophan Metabolism to Stimulate CD8+ T-cell Function in Colorectal Cancer

Metformin as an immunomodulatory agent in enhancing head and neck squamous cell carcinoma therapies

Head and neck squamous cell carcinoma (HNSCC) remains a significant clinical challenge due to its aggressive behavior and poor prognosis, making the development of novel therapeutics with enhanced efficacy and minimal side effects critical. Metformin, a widely used antidiabetic agent, has recently emerged as a potential adjunctive therapy for HNSCC, exhibiting both direct anti-tumor and immunomodulatory effects. This review comprehensively explores the multifaceted role of metformin in shaping the tumor immune microenvironment within HNSCC. We emphasize its pivotal role in modulating immune cell populations and its potential for synergistic action with immunotherapeutic strategies. Furthermore, we address the current challenges associated with optimizing dosing regimens, identifying predictive biomarkers, and integrating metformin with immunotherapy. By dissecting these aspects, this review aims to pave the way for the development of personalized HNSCC treatment strategies that fully exploit the therapeutic potential of metformin.

Tumor Microenvironment: Obstacles and Opportunities for T Cell-Based Tumor Immunotherapies

The complex composition and dynamic change of the tumor microenvironment (TME), mainly consisting of tumor cells, immune cells, stromal cells, and extracellular components, significantly impede the effector function of cytotoxic T lymphocytes (CTL), thus representing a major obstacle for tumor immunotherapies. In this review, we summarize and discuss the impacts and underlying mechanisms of major elements in the TME (different cell types, extracellular matrix, nutrients and metabolites, etc.) on the infiltration, survival, and effector functions of T cells, mainly CD8+ CTLs. Moreover, we also highlight recent advances that may potentiate endogenous antitumor immunity and improve the efficacy of T cell-based immunotherapies in patients with cancer by manipulating components inside/outside of the TME. A deeper understanding of the effects and action mechanisms of TME components on the tumor-eradicating ability of CTLs may pave the way for discovering new targets to augment endogenous antitumor immunity and for designing combinational therapeutic regimens to enhance the efficacy of tumor immunotherapies in the clinic.

Pan-cancer bioinformatics analysis of TIPRL in human tumors

INTRODUCTION

The TOR signaling pathway regulator-like (TIPRL) gene plays a multifaceted role in cancer, yet its pan-cancer profile remains underexplored. This study investigates TIPRL expression across multiple cancers and its associations with survival, genetic alterations, immune infiltration, and functional pathways, providing insights into TIPRL's role as a potential prognostic and therapeutic target.

METHODS

TIPRL expression and prognostic significance across tumor types were analyzed using TCGA_GTEx and CPTAC data in R software and platforms like GEPIA2 and UALCAN. Genetic alterations and 3D structures were evaluated through cBioPortal. Associations with RNA modifications, immune checkpoints, immune cell infiltration, TMB, MSI, HRD, and enriched pathways were assessed via R and STRING databases, employing survival analysis, ssGSEA, and enrichment analyses.

RESULTS

TIPRL expression was elevated in most cancers, with significant stage-specific associations observed in KICH, KIRP, and LUSC. High TIPRL expression correlated with worse overall survival in ACC, BRCA, HNSC, KICH, LIHC, and MESO, suggesting its role in prognosis. Genetic analysis identified amplifications as the main alteration, with varied clinical relevance across cancers. RNA modifications in TIPRL, particularly m1A, m5C, and m6A, suggested potential regulatory mechanisms. Immune infiltration analysis revealed TIPRL's varied correlations with immune cell types and immune scores, differing by cancer type. TIPRL also positively correlated with TMB, MSI, and HRD in several cancers, indicating its association with genomic instability. Enrichment analyses highlighted TIPRL's involvement in processes like oxidative phosphorylation and autophagy, underscoring its influence in tumorigenesis.

CONCLUSION

These findings establish TIPRL as a significant biomarker in cancer progression and immune regulation, warranting further exploration into its therapeutic implications across diverse tumor types.

Drug functional remapping: a new promise for tumor immunotherapy

The research and development of new anti-cancer drugs face challenges such as high costs, lengthy development cycles, and limited data on side effects. In contrast, the clinical safety and side effects of traditional drugs have been well established through long-term use. The development or repurposing of traditional drugs with potential applications in cancer treatment offers an economical, feasible, and promising strategy for new drug development. This article reviews the novel applications of traditional drugs in tumor immunotherapy, discussing how they can enhance tumor treatment efficacy through functional repositioning, while also reducing development time and costs. Recent advancements in cancer immunotherapy have revolutionized treatment options, but resistance to ICIs remains a significant challenge. Drug repurposing has emerged as a promising strategy to identify novel agents that can enhance the efficacy of immunotherapies by overcoming ICI resistance. A study suggests that drug repositioning has the potential to modulate immune cell activity or alter the tumor microenvironment, thereby circumventing the resistance mechanisms associated with immune checkpoint blockade. This approach provides a rapid and cost-effective pathway for identifying therapeutic candidates that can be quickly transitioned into clinical trials. To improve the effectiveness of tumor immunotherapy, it is crucial to explore systematic methods for identifying repurposed drug candidates. Methods such as high-throughput screening, computational drug repositioning, and bioinformatic analysis have been employed to efficiently identify potential candidates for cancer treatment. Furthermore, leveraging databases related to immunotherapy and drug repurposing can provide valuable resources for drug discovery and facilitate the identification of promising compounds. It focuses on the latest advancements in the use of antidiabetic drugs, antihypertensive agents, weight-loss medications, antifungal agents, and antiviral drugs in tumor immunotherapy, examining their mechanisms of action, clinical application prospects, and associated challenges. In this context, our aim is to explore these strategies and highlight their potential for expanding the therapeutic options available for cancer immunotherapy, providing valuable references for cancer research and treatment.

Metformin-induced RBMS3 expression enhances ferroptosis and suppresses ovarian cancer progression

Metformin (Met), a widely used type II diabetes medication, has shown anti-cancer properties in various cancers. RBMS3 is a tumor suppressor implicated in several cancers, including ovarian cancer. Ferroptosis, a novel form of programmed cell death, is gaining attention in cancer research. This study explores whether metformin induces ferroptosis and inhibits ovarian cancer progression through the RBMS3 pathway. We used a CCK-8 assay to determine the optimal metformin concentration for ovarian cancer cells. Metformin's effects were further evaluated using EdU assay and flow cytometry. To clarify its mechanism, we employed programmed cell death inhibitors and measured levels of MDA (Malondialdehyde), GSH (Glutathione), and Fe²⁺. Ferroptosis-related proteins and RBMS3 expression in ovarian cancer tissues and cells were assessed via RT-qPCR and Western blotting. A xenograft mouse model was used to observe metformin's effects on tumor growth. Metformin inhibited the viability of ovarian cancer A2780 cells, promoted ferroptosis, increased MDA and Fe²⁺ levels, and reduced GSH. It upregulated ferroptosis-related genes while downregulating GPX4 and SLC7A11. Although RBMS3 was reduced in cancer cells, metformin increased its expression, and silencing RBMS3 reversed metformin's effects. In vivo, metformin inhibited tumor growth, which was negated by RBMS3 silencing. Our findings suggest that metformin promotes ferroptosis and inhibits ovarian cancer progression by upregulating RBMS3, offering a promising direction for clinical application in ovarian cancer treatment.

STING in cancer immunoediting: Modeling tumor-immune dynamics throughout cancer development

Cancer immunoediting is a dynamic process of tumor-immune system interaction that plays a critical role in cancer development and progression. Recent studies have highlighted the importance of innate signaling pathways possessed by both cancer cells and immune cells in this process. The STING molecule, a pivotal innate immune signaling molecule, mediates DNA-triggered immune responses in both cancer cells and immune cells, modulating the anti-tumor immune response and shaping the efficacy of immunotherapy. Emerging evidence has shown that the activation of STING signaling has dual opposing effects in cancer progression, simultaneously provoking and restricting anti-tumor immunity, and participating in every phase of cancer immunoediting, including immune elimination, equilibrium, and escape. In this review, we elucidate the roles of STING in the process of cancer immunoediting and discuss the dichotomous effects of STING agonists in the cancer immunotherapy response or resistance. A profound understanding of the sophisticated roles of STING signaling pathway in cancer immunoediting would potentially inspire the development of novel cancer therapeutic approaches and overcome the undesirable protumor effects of STING activation.

The colorectal cancer microenvironment: Preclinical progress in identifying targets for cancer therapy

Colorectal cancer (CRC) is a common cancer with high mortality rates. Despite progress in treatment, it remains an incurable disease for many patients. In CRC, the tumor microenvironment (TME) plays critical roles in tumor growth, progression, patients' prognosis, and response to treatments. Understanding TME complexities is important for developing effective therapies. In vitro and in vivo preclinical models are critical in understanding the disease, discovering potential targets, and developing effective therapeutics. In this review, we focus on preclinical research studies associated with modulation of the TME in CRC. These models give insights into understanding the role of stroma and immune cell components of the TME in CRC and improve clinical responses, providing insights in novel treatment options. Various studies have focused on targeting the TME in CRC to improve responses to different therapeutic approaches. These include identifying targets for cancer therapies, targeting molecular signaling, and enhancing the efficacy of immunotherapeutic modalities. Furthermore, targeting stromal and angiogenic factors in the TME may provide new therapeutic options. Overall, understanding and targeting the TME in CRC is a promising approach for improving therapeutic outcomes.

Metformin blocks BIK1-mediated CPK28 phosphorylation and enhances plant immunity

INTRODUCTION

Metformin (MET), derived from Galega officinalis, stands as the primary first-line medication for the treatment of type 2 diabetes (T2D). Despite its well-documented benefits in mammalian cellular processes, its functions and underlying mechanisms in plants remain unclear.

OBJECTIVES

This study aimed to elucidate MET's role in inducing plant immunity and investigate the associated mechanisms.

METHODS

To investigate the impact of MET on enhancing plant immune responses, we conducted assays measuring defense gene expression, reactive oxygen species (ROS) accumulation, mitogen-activated protein kinase (MAPK) phosphorylation, and pathogen infection. Additionally, surface plasmon resonance (SPR) and microscale thermophoresis (MST) techniques were employed to identify MET targets. Protein-protein interactions were analyzed using a luciferase complementation assay and a co-immunoprecipitation assay.

RESULTS

Our findings revealed that MET boosts plant disease resistance by activating MAPKs, upregulating the expression of downstream defense genes, and fortifying the ROS burst. CALCIUM-DEPENDENT PROTEIN KINASE 28 (CPK28) was identified as a target of MET. It inhibited the interaction between BOTRYTIS-INDUCED KINASE 1 (BIK1) and CPK28, blocking CPK28 threonine 76 (T76) transphosphorylation by BIK1, and alleviating the negative regulation of immune responses by CPK28. Moreover, MET enhanced disease resistance in tomato, pepper, and soybean plants.

CONCLUSION

Collectively, our data suggest that MET enhances plant immunity by blocking BIK1-mediated CPK28 phosphorylation.

Saffron improves the efficacy of immunotherapy for colorectal cancer through the IL-17 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Saffron is one of the traditional medicinal herbs, which contains various active ingredients, such as safranal, crocin, saffron acid, etc. It has anti-inflammatory, antioxidant, and anti-cancer properties, and is widely used in clinical practice. The anti-cancer efficacy of saffron has been previously confirmed, but its anti-cancer mechanism in colorectal cancer remains unclear.

OBJECTIVE

We investigated the effect of active compounds of saffron on the efficacy of immunotherapy for colorectal cancer.

METHODS

TCMSP and liquid chromatography-mass spectrometry analysis (LC-MS), GeneCards, and DisGeNET databases were used to identify the active compounds of saffron, drug targets and the disease targets of colorectal cancer. They were then subjected to Gene Ontology Enrichment (GO) and Signalling Pathway Enrichment (KEGG) analyses. The core targets and corresponding compounds were selected for molecular docking. The effect of active components of saffron on the proliferation of CT26 and HCT116 cells was investigated using the cell counting kit-8 (CCK-8). In vitro experiments were conducted by subcutaneous injection of CT26 cells to establish a colon cancer model. Enzyme-linked immunosorbent assay (ELISA), western blotting (WB), real-time polymerase chain reaction (RT-PCR), immunohistochemistry (IHC), and flow cytometry (FCM) were employed to validate the effects of saffron on colorectal cancer immunotherapy.

RESULTS

1. LC-MS analysis revealed that the main active component of saffron extract was crocin. The active chemicals of saffron intersected with 170 colorectal cancer targets, with 17 predicting targets for saffron treatment. GO and KEGG enrichment analyses revealed that the active components of saffron can prevent colorectal cancer development by enhancing Th17 cell differentiation and the IL-17 signaling pathway. 2. In vitro studies revealed that saffron alcohol extract, crocin, and safranal can suppress the proliferation of CT26 and HCT116 cells. 3. In vivo studies showed that crocin and safranal can increase the body mass and decrease the tumor mass of loaded mice, decrease the serum level of IL-17, and lower the mRNA expression level of IL-17, IL-6, TNF-α, TGF-β, and PD-L1 and IL-17, PD-L1 protein in tumors. This inhibitory effect was strengthened after combined immunotherapy. In addition, saffron modulated CD4+ and CD8+ T cells and the CD4+/CD8+T ratio in mouse spleens.

CONCLUSION

The active components of saffron can reduce the expression of inflammatory factors and ameliorate the immunological microenvironment of tumors via the IL-17 signaling pathway, thereby improving the efficacy of immunotherapy for colorectal cancer. This study provides pharmacological support for the application of saffron in enhancing the efficacy of immunotherapy for colorectal cancer.

Nanomaterial-enabled metabolic reprogramming strategies for boosting antitumor immunity

Immunotherapy has become a crucial strategy in cancer treatment, but its effectiveness is often constrained. Most cancer immunotherapies focus on stimulating T-cell-mediated immunity by driving the cancer-immunity cycle, which includes tumor antigen release, antigen presentation, T cell activation, infiltration, and tumor cell killing. However, metabolism reprogramming in the tumor microenvironment (TME) supports the viability of cancer cells and inhibits the function of immune cells within this cycle, presenting clinical challenges. The distinct metabolic needs of tumor cells and immune cells require precise and selective metabolic interventions to maximize therapeutic outcomes while minimizing adverse effects. Recent advances in nanotherapeutics offer a promising approach to target tumor metabolism reprogramming and enhance the cancer-immunity cycle through tailored metabolic modulation. In this review, we explore cutting-edge nanomaterial strategies for modulating tumor metabolism to improve therapeutic outcomes. We review the design principles of nanoplatforms for immunometabolic modulation, key metabolic pathways and their regulation, recent advances in targeting these pathways for the cancer-immunity cycle enhancement, and future prospects for next-generation metabolic nanomodulators in cancer immunotherapy. We expect that emerging immunometabolic modulatory nanotechnology will establish a new frontier in cancer immunotherapy in the near future.

Bibliometric analysis of metformin as an immunomodulator (2013-2024)

Background

Metformin, the frontline treatment for diabetes, has considerable potential as an immunomodulator; however, detailed bibliometric analyses on this subject are limited.

Methods

This study extracted 640 relevant articles from the Web of Science (WOS) Core Collection and conducted visual analyses using Microsoft Excel, VOSviewer, and CiteSpace.

Results

The findings showed that research on the immunomodulatory function of metformin has grown steadily since 2017, with China and the United States being the leading contributors. These studies have mostly been published in journals such as the International Journal of Molecular Sciences, Cancers, Frontiers in Immunology, and Scientific Reports. Keyword co-occurrence analysis highlighted metformin's role as an immunomodulator, particularly in the context of the tumor immune microenvironment, immunosuppressive checkpoints, and metformin derivatives. Recent research has highlighted metformin's application in aging, autoimmune diseases, COVID-19, and tuberculosis. Additionally, its role in regulating inflammation and gut microbiota is also being investigated.

Conclusion

Overall, the immunomodulatory effects of metformin were investigated in anti-tumor, antiviral, anti-aging, and autoimmune disease research. This highlights the scope of metformin use in these fields, while also significantly enhancing its clinical value as a repurposed drug.

Targeting metabolic pathway enhance CAR-T potency for solid tumor

Chimeric antigen receptor (CAR) T cells have great potential in cancer therapy, particularly in treating hematologic malignancies. However, their efficacy in solid tumors remains limited, with a significant proportion of patients failing to achieve long-term complete remission. One major challenge is the premature exhaustion of CAR-T cells, often due to insufficient metabolic energy. The survival, function and metabolic adaptation of CAR-T cells are key determinants of their therapeutic efficacy. We explore how targeting metabolic pathways in the tumor microenvironment can enhance CAR-T cell therapy by addressing metabolic competition and immunosuppression that impair CAR-T cell function. Tumors undergo metabolically reprogrammed to meet their rapid proliferation, thereby modulating metabolic pathways in immune cells to promote immunosuppression. The distinct metabolic requirements of tumors and T cells create a competitive environment, affecting the efficacy of CAR-T cell therapy. Recent research on glucose, lipid and amino acid metabolism, along with the interactions between tumor and immune cell metabolism, has revealed that targeting these metabolic processes can enhance antitumor immune responses. Combining metabolic interventions with existing antitumor therapies can fulfill the metabolic demands of immune cells, providing new ideas for tumor immunometabolic therapies. This review discusses the latest advances in the immunometabolic mechanisms underlying tumor immunosuppression, their implications for immunotherapy, and summarizes potential metabolic targets to improve the efficacy of CAR-T therapy.

Engineering bacteria for cancer immunotherapy by inhibiting IDO activity and reprogramming CD8+ T cell response

Inhibiting indoleamine 2,3 dioxygenase (IDO) for anticancer therapy has garnered significant attention in recent years. However, current IDO inhibitors face significant challenges which limit their clinical application. Here, we genetically engineered a high tryptophan-expressing Clostridium butyricum (L-Trp CB) strain that can colonize tumors strictly following systemic administration. We revealed that butyrate produced by L-Trp CB can inhibit IDO activity, preventing tryptophan catabolism and kynurenine accumulation in tumors. In addition, the large released tryptophan by L-Trp CB can provide discrete signals that support CD8+ T cell activation and energy metabolism within the tumor microenvironment. We observed that L-Trp CB significantly restored the proportion and function of CD8+ T cells, leading to significantly delayed tumor growth in both mouse and rabbit multiple tumor models with limited side effects. We here provide a synthetic biology treatment strategy for enhanced tumor immunotherapy by inhibiting IDO activity and reprogramming CD8+ T cell response in tumors.

NIT2 dampens BRD1 phase separation and restrains oxidative phosphorylation to enhance chemosensitivity in gastric cancer

5-Fluorouracil (5-FU) chemoresistance contributes to poor therapeutic response and prognosis of gastric cancer (GC), for which effective strategies to overcome chemoresistance are limited. Here, using a CRISPR-Cas9 system, we identified that nitrilase family member 2 (NIT2) reverses chemoresistance independent of its metabolic function. Depletion or low expression of NIT2 led to 5-FU resistance in GC cell lines, patient-derived organoids, and xenografted tumors. Mechanistically, NIT2 interacted with bromodomain-containing protein 1 (BRD1) to inhibit HBO1-mediated acetylation of histone H3 at lysine-14 (H3K14ac) and RELA-targeted oxidative phosphorylation (OXPHOS) gene expression. Upon 5-FU stimulation, NIT2 phosphorylation by Src at Y49 promoted the dissociation of NIT2 from BRD1, followed by binding to E3 ligase CCNB1IP1, causing autophagic degradation of NIT2. Consequently, reduced NIT2 protein resulted in BRD1 forming phase separation and binding to histone H3, as well as increased RELA stability due to suppression of inhibitor of growth family member 4-mediated RELA ubiquitination. In addition, NIT2 expression negatively correlated with H3K14ac and OXPHOS and positively correlated with the chemotherapeutic responses and prognosis of patients with GC. Our findings reveal the moonlighting function of NIT2 in chemoresistance and underscore that OXPHOS blockade by metformin enhances 5-FU chemosensitivity upon NIT2 loss.

Netupitant Inhibits the Proliferation of Breast Cancer Cells by Targeting AGK

Background: Currently, there is a significant lack of effective pharmacological agents for the treatment of breast cancer. Acylglycerol Kinase (AGK), a lipid kinase, has been found to be aberrantly expressed in breast cancer and is closely associated with tumor proliferation, migration, and invasion. However, no clinical anti-tumor drugs specifically targeting this kinase have been developed. Methods: siRNA was utilized to knock down the AGK gene; CCK8 and colony formation assays were employed to evaluate the in vitro proliferative capacity of tumor cells. Molecular dynamics simulations and BIL assays were conducted to analyze drug binding affinity. Annexin V/PI staining was used to assess apoptotic phenomena; subcutaneous xenograft tumor experiments in nude mice were performed to confirm the in vivo anti-tumor efficacy of the drug. Results: Netupitant exhibited stable binding affinity for AGK and interacted with amino acids within the ATP-binding region of the enzyme. The IC50 values for the SK-BR-3 and MDA-MB-231 cell lines were determined as 16.15 ± 4.25 µmol/L and 24.02 ± 4.19 µmol/L, respectively; at a concentration of 2.5 µmol/L, Netupitant effectively inhibited clonogenic capacity in breast cancer cells; furthermore, treatment with 10 µmol/L significantly induced apoptosis in these cells. Doses of 50 mg/kg and 100 mg/kg Netupitant markedly suppressed growth rates of subcutaneous xenograft tumors in nude mice while also promoting apoptotic processes. Both in vivo and in vitro studies indicated that Netupitant could inhibit the activation of the PI3K/AKT/mTOR signaling pathway. Conclusions: By targeting AGK, Netupitant inhibits its kinase activity, which leads to reduced phosphorylation levels of PTEN, thereby suppressing the activation of the PI3K/AKT/mTOR signaling pathway and ultimately resulting in apoptosis in breast cancer cells.

6-Phosphogluconate dehydrogenase promotes glycolysis and fatty acid synthesis by inhibiting the AMPK pathway in lung adenocarcinoma cells

Abnormal metabolism has emerged as a prominent hallmark of cancer and plays a pivotal role in carcinogenesis and progression of lung adenocarcinoma (LUAD). In this study, single-cell sequencing revealed that the metabolic enzyme 6-phosphogluconate dehydrogenase (PGD), which is a critical regulator of the pentose phosphate pathway (PPP), is significantly upregulated in the malignant epithelial cell subpopulation during malignant progression. However, the precise functional significance of PGD in LUAD and its underlying mechanisms remain elusive. Through the integration of TCGA database analysis and LUAD tissue microarray data, it was found that PGD expression was significantly upregulated in LUAD and closely correlated with a poor prognosis in LUAD patients. Moreover, in vitro and in vivo analyses demonstrated that PGD knockout and inhibition of its activity mitigated the proliferation, migration, and invasion of LUAD cells. Mechanistically, immunoprecipitation-mass spectrometry (IP-MS) revealed for the first time that IQGAP1 is a robust novel interacting protein of PGD. PGD decreased p-AMPK levels by competitively interacting with the IQ domain of the known AMPKα binding partner IQGAP1, which promoted glycolysis and fatty acid synthesis in LUAD cells. Furthermore, we demonstrated that the combination of Physcion (a PGD-specific inhibitor) and metformin (an AMPK agonist) could inhibit tumor growth more effectively both in vivo and in vitro. Collectively, these findings suggest that PGD is a potential prognostic biomarker and therapeutic target for LUAD.

NRF2 signaling and amino acid metabolism in cancer

Alterations in amino acid metabolism have emerged as a critical component in cancer biology, influencing various aspects of tumor initiation, progression, and metastasis. This review explores how amino acids, beyond their role as protein building blocks, are essential for redox balance, cell proliferation, metastasis, signaling/epigenetic regulation, and tumor microenvironment modulation in cancer. We particularly focus on the intricate relationship between amino acid metabolism and nuclear factor erythroid 2-related factor 2 (NRF2) signaling, a master regulator of oxidative stress response that frequently hyperactivated in cancer. Increasing evidence indicates that NRF2 is a key player in amino acid metabolism, orchestrating metabolism of cysteine, glutamine, and serine/glycine to promote cancer cell survival and growth. This comprehensive analysis provides insights into potential therapeutic strategies targeting the NRF2-amino acid metabolism axis, offering new avenues for cancer treatment that address multiple aspects of tumor biology.

Metabolic reprogramming and immune evasion: the interplay in the tumor microenvironment

Tumor cells possess complex immune evasion mechanisms to evade immune system attacks, primarily through metabolic reprogramming, which significantly alters the tumor microenvironment (TME) to modulate immune cell functions. When a tumor is sufficiently immunogenic, it can activate cytotoxic T-cells to target and destroy it. However, tumors adapt by manipulating their metabolic pathways, particularly glucose, amino acid, and lipid metabolism, to create an immunosuppressive TME that promotes immune escape. These metabolic alterations impact the function and differentiation of non-tumor cells within the TME, such as inhibiting effector T-cell activity while expanding regulatory T-cells and myeloid-derived suppressor cells. Additionally, these changes lead to an imbalance in cytokine and chemokine secretion, further enhancing the immunosuppressive landscape. Emerging research is increasingly focusing on the regulatory roles of non-tumor cells within the TME, evaluating how their reprogrammed glucose, amino acid, and lipid metabolism influence their functional changes and ultimately aid in tumor immune evasion. Despite our incomplete understanding of the intricate metabolic interactions between tumor and non-tumor cells, the connection between these elements presents significant challenges for cancer immunotherapy. This review highlights the impact of altered glucose, amino acid, and lipid metabolism in the TME on the metabolism and function of non-tumor cells, providing new insights that could facilitate the development of novel cancer immunotherapies.

Metformin induces tumor immunogenic cell death in ovarian cancer by activating AMPK pathway

Inducing immunogenic cell death (ICD) process may be an important antitumor strategy in ovarian cancer (OC). Metformin (Met) has been shown to have antitumor effects in OC, but whether it mediates the ICD to inhibit OC process is unclear. Human OC cell lines (SKOV3 and A2780) were treated with Met. Dendritic cell (DC) and CD8+T cells were isolated from the peripheral blood mononuclear cells of volunteers. Cell counting kit 8 assay was used to measure cell viability, and immunofluorescence staining was performed to detect the percentages of membrane and intracellular calreticulin (CRT). CRT level, DC maturation and effector cell activation were evaluated by flow cytometry. The levels of IL-10 and IFN-γ, as well as the releasements of HMGB1 and ATP, were detected using corresponding kits. The protein levels of heat shock protein 70/90 (HSP70/90) and AMPKα were tested by western blot analysis, and the mRNA levels of CD80, CD86, IL-10, and IFN-γ were measured by quantitative real-time PCR. Colony formation assay was utilized for assessing cell cytotoxicity. Mice transplanted tumor model was constructed to assess the effect of Met on OC tumor growth, and immunohistochemistry staining was used to analyze CD80+ and CD86+ cells in mice tumor tissues. Our data showed that Met inhibited OC cell viability and induced CRT exposure. Besides, Met could promote the release of HMGB1 and ATP, as well as induce DC maturation. In vivo experiments suggested that Met restrained OC tumor growth via activating antitumor immune response. Moreover, Met activated AMPK pathway, and silenced AMPK pathway reversed the promoting effect of Met on CRT exposure and the releasements of HMGB1 and ATP in OC cells. In conclusion, Met induced ICD-mediated immune destruction in OC via activating AMPK pathway, indicating that Met might be used in the immunotherapy of OC.

Immunomodulatory molecules in colorectal cancer liver metastasis

Colorectal cancer (CRC) ranks as the third most common cancer and the second leading cause of cancer-related deaths. According to clinical diagnosis and treatment, liver metastasis occurs in approximately 50 % of CRC patients, indicating a poor prognosis. The unique immune tolerance of the liver fosters an immunosuppressive tumor microenvironment (TME). In the context of tumors, numerous membrane and secreted proteins have been linked to tumor immune evasion as immunomodulatory molecules, but much remains unknown about how these proteins contribute to immune evasion in colorectal cancer liver metastasis (CRLM). This article reviews recently discovered membrane and secreted proteins with roles as both immunostimulatory and immunosuppressive molecules within the TME that influence immune evasion in CRC primary and metastatic lesions, particularly their mechanisms in promoting CRLM. This article also addresses screening strategies for identifying proteins involved in immune evasion in CRLM and provides insights into potential protein targets for treating CRLM.

The significant role of amino acid metabolic reprogramming in cancer

Amino acid metabolism plays a pivotal role in tumor microenvironment, influencing various aspects of cancer progression. The metabolic reprogramming of amino acids in tumor cells is intricately linked to protein synthesis, nucleotide synthesis, modulation of signaling pathways, regulation of tumor cell metabolism, maintenance of oxidative stress homeostasis, and epigenetic modifications. Furthermore, the dysregulation of amino acid metabolism also impacts tumor microenvironment and tumor immunity. Amino acids can act as signaling molecules that modulate immune cell function and immune tolerance within the tumor microenvironment, reshaping the anti-tumor immune response and promoting immune evasion by cancer cells. Moreover, amino acid metabolism can influence the behavior of stromal cells, such as cancer-associated fibroblasts, regulate ECM remodeling and promote angiogenesis, thereby facilitating tumor growth and metastasis. Understanding the intricate interplay between amino acid metabolism and the tumor microenvironment is of crucial significance. Expanding our knowledge of the multifaceted roles of amino acid metabolism in tumor microenvironment holds significant promise for the development of more effective cancer therapies aimed at disrupting the metabolic dependencies of cancer cells and modulating the tumor microenvironment to enhance anti-tumor immune responses and inhibit tumor progression.

Mesoporous manganese nanocarrier target delivery metformin for the co-activation STING pathway to overcome immunotherapy resistance

Targeting the stimulator of interferon genes (STING) pathway is a promising strategy to overcome primary resistance to immune checkpoint inhibitors in non-small cell lung cancer with the STK11 mutation. We previously found metformin enhances the STING pathway and thus promotes immune response. However, its low concentration in tumors limits its clinical use. Here, we constructed high-mesoporous Mn-based nanocarrier loading metformin nanoparticles (Mn-MSN@Met-M NPs) that actively target tumors and respond to release higher concentration of Mn2+ ions and metformin. The NPs significantly enhanced the T cells to kill lung cancer cells with the STK11 mutant. The mechanism shows that enhanced STING pathway activation promotes STING, TBKI, and IRF3 phosphorylation through Mn2+ ions and metformin release from NPs, thus boosting type I interferon production. In vivo, NPs in combination with a PD-1 inhibitor effectively decreased tumor growth. Collectively, we developed a Mn-MSN@Met-M nanoactivator to intensify immune activation for potential cancer immunotherapy.

Will AMPK be a potential therapeutic target for hepatocellular carcinoma?

Cancer is the disease that poses the greatest threat to human health today. Among them, hepatocellular carcinoma (HCC) is particularly prominent due to its high recurrence rate and extremely low five-year postoperative survival rate. In addition to surgical treatment, radiotherapy, chemotherapy, and immunotherapy are the main methods for treating HCC. Due to the natural drug resistance of chemoradiotherapy and targeted drugs, satisfactory results have not been achieved in terms of therapeutic efficacy and cost. AMP-Activated Protein Kinase (AMPK) is a serine/threonine protein kinase. It mainly coordinates the metabolism and transformation of energy between cells, which maintaining a balance between energy supply and demand. The processes of cell growth, proliferation, autophagy, and survival all involve various reaction of cells to energy changes. The regulatory role of AMPK in cellular energy metabolism plays an important role in the occurrence, development, treatment, and prognosis of HCC. Here, we reviewed the latest progress on the regulatory role of AMPK in the occurrence and development of HCC. Firstly, the molecular structure and activation mechanism of AMPK were introduced. Secondly, the emerging regulator related to AMPK and tumors were elaborated. Next, the multitasking roles of AMPK in the occurrence and development mechanism of HCC were discussed separately. Finally, the translational implications and the challenges of AMPK-targeted therapies for HCC treatment were elaborated. In summary, these pieces of information suggest that AMPK can serve as a promising specific therapeutic target for the treatment of HCC.

Action of circulating and infiltrating B cells in the immune microenvironment of colorectal cancer by single-cell sequencing analysis

BACKGROUND

The complexity of the immune microenvironment has an impact on the treatment of colorectal cancer (CRC), one of the most prevalent malignancies worldwide. In this study, multi-omics and single-cell sequencing techniques were used to investigate the mechanism of action of circulating and infiltrating B cells in CRC. By revealing the heterogeneity and functional differences of B cells in cancer immunity, we aim to deepen our understanding of immune regulation and provide a scientific basis for the development of more effective cancer treatment strategies.

AIM

To explore the role of circulating and infiltrating B cell subsets in the immune microenvironment of CRC, explore the potential driving mechanism of B cell development, analyze the interaction between B cells and other immune cells in the immune microenvironment and the functions of communication molecules, and search for possible regulatory pathways to promote the anti-tumor effects of B cells.

METHODS

A total of 69 paracancer (normal), tumor and peripheral blood samples were collected from 23 patients with CRC from The Cancer Genome Atlas database (https://portal.gdc.cancer.gov/). After the immune cells were sorted by multicolor flow cytometry, the single cell transcriptome and B cell receptor group library were sequenced using the 10X Genomics platform, and the data were analyzed using bioinformatics tools such as Seurat. The differences in the number and function of B cell infiltration between tumor and normal tissue, the interaction between B cell subsets and T cells and myeloid cell subsets, and the transcription factor regulatory network of B cell subsets were explored and analyzed.

RESULTS

Compared with normal tissue, the infiltrating number of CD20⁺B cell subsets in tumor tissue increased significantly. Among them, germinal center B cells (GCB) played the most prominent role, with positive clone expansion and heavy chain mutation level increasing, and the trend of differentiation into memory B cells increased. However, the number of plasma cells in the tumor microenvironment decreased significantly, and the plasma cells secreting IgA antibodies decreased most obviously. In addition, compared with the immune microenvironment of normal tissues, GCB cells in tumor tissues became more closely connected with other immune cells such as T cells, and communication molecules that positively regulate immune function were significantly enriched.

CONCLUSION

The role of GCB in CRC tumor microenvironment is greatly enhanced, and its affinity to tumor antigen is enhanced by its significantly increased heavy chain mutation level. Meanwhile, GCB has enhanced its association with immune cells in the microenvironment, which plays a positive anti-tumor effect.

Action of circulating and infiltrating B cells in the immune microenvironment of colorectal cancer by single-cell sequencing analysis

BACKGROUND

The complexity of the immune microenvironment has an impact on the treatment of colorectal cancer (CRC), one of the most prevalent malignancies worldwide. In this study, multi-omics and single-cell sequencing techniques were used to investigate the mechanism of action of circulating and infiltrating B cells in CRC. By revealing the heterogeneity and functional differences of B cells in cancer immunity, we aim to deepen our understanding of immune regulation and provide a scientific basis for the development of more effective cancer treatment strategies.

AIM

To explore the role of circulating and infiltrating B cell subsets in the immune microenvironment of CRC, explore the potential driving mechanism of B cell development, analyze the interaction between B cells and other immune cells in the immune microenvironment and the functions of communication molecules, and search for possible regulatory pathways to promote the anti-tumor effects of B cells.

METHODS

A total of 69 paracancer (normal), tumor and peripheral blood samples were collected from 23 patients with CRC from The Cancer Genome Atlas database (https://portal.gdc.cancer.gov/). After the immune cells were sorted by multicolor flow cytometry, the single cell transcriptome and B cell receptor group library were sequenced using the 10X Genomics platform, and the data were analyzed using bioinformatics tools such as Seurat. The differences in the number and function of B cell infiltration between tumor and normal tissue, the interaction between B cell subsets and T cells and myeloid cell subsets, and the transcription factor regulatory network of B cell subsets were explored and analyzed.

RESULTS

Compared with normal tissue, the infiltrating number of CD20+B cell subsets in tumor tissue increased significantly. Among them, germinal center B cells (GCB) played the most prominent role, with positive clone expansion and heavy chain mutation level increasing, and the trend of differentiation into memory B cells increased. However, the number of plasma cells in the tumor microenvironment decreased significantly, and the plasma cells secreting IgA antibodies decreased most obviously. In addition, compared with the immune microenvironment of normal tissues, GCB cells in tumor tissues became more closely connected with other immune cells such as T cells, and communication molecules that positively regulate immune function were significantly enriched.

CONCLUSION

The role of GCB in CRC tumor microenvironment is greatly enhanced, and its affinity to tumor antigen is enhanced by its significantly increased heavy chain mutation level. Meanwhile, GCB has enhanced its association with immune cells in the microenvironment, which plays a positive anti-tumor effect.

Amino acid transporters within the solute carrier superfamily: Underappreciated proteins and novel opportunities for cancer therapy

BACKGROUND

Solute carrier (SLC) transporters, a diverse family of membrane proteins, are instrumental in orchestrating the intake and efflux of nutrients including amino acids, vitamins, ions, nutrients, etc, across cell membranes. This dynamic process is critical for sustaining the metabolic demands of cancer cells, promoting their survival, proliferation, and adaptation to the tumor microenvironment (TME). Amino acids are fundamental building blocks of cells and play essential roles in protein synthesis, nutrient sensing, and oncogenic signaling pathways. As key transporters of amino acids, SLCs have emerged as crucial players in maintaining cellular amino acid homeostasis, and their dysregulation is implicated in various cancer types. Thus, understanding the intricate connections between amino acids, SLCs, and cancer is pivotal for unraveling novel therapeutic targets and strategies.

SCOPE OF REVIEW

In this review, we delve into the significant impact of amino acid carriers of the SLCs family on the growth and progression of cancer and explore the current state of knowledge in this field, shedding light on the molecular mechanisms that underlie these relationships and highlighting potential avenues for future research and clinical interventions.

MAJOR CONCLUSIONS

Amino acids transportation by SLCs plays a critical role in tumor progression. However, some studies revealed the tumor suppressor function of SLCs. Although several studies evaluated the function of SLC7A11 and SLC1A5, the role of some SLC proteins in cancer is not studied well. To exert their functions, SLCs mediate metabolic rewiring, regulate the maintenance of redox balance, affect main oncogenic pathways, regulate amino acids bioavailability within the TME, and alter the sensitivity of cancer cells to therapeutics. However, different therapeutic methods that prevent the function of SLCs were able to inhibit tumor progression. This comprehensive review provides insights into a rapidly evolving area of cancer biology by focusing on amino acids and their transporters within the SLC superfamily.

New insights into immune cells in cancer immunotherapy: from epigenetic modification, metabolic modulation to cell communication

Cancer is one of the leading causes of death worldwide, and more effective ways of attacking cancer are being sought. Cancer immunotherapy is a new and effective therapeutic method after surgery, radiotherapy, chemotherapy, and targeted therapy. Cancer immunotherapy aims to kill tumor cells by stimulating or rebuilding the body's immune system, with specific efficiency and high safety. However, only few tumor patients respond to immunotherapy and due to the complex and variable characters of cancer immune escape, the behavior and regulatory mechanisms of immune cells need to be deeply explored from more dimensions. Epigenetic modifications, metabolic modulation, and cell-to-cell communication are key factors in immune cell adaptation and response to the complex tumor microenvironment. They collectively determine the state and function of immune cells through modulating gene expression, changing in energy and nutrient demands. In addition, immune cells engage in complex communication networks with other immune components, which are mediated by exosomes, cytokines, and chemokines, and are pivotal in shaping the tumor progression and therapeutic response. Understanding the interactions and combined effects of such multidimensions mechanisms in immune cell modulation is important for revealing the mechanisms of immunotherapy failure and developing new therapeutic targets and strategies.

Mitochondria-Modulating Liposomes Reverse Radio-Resistance for Colorectal Cancer

Complete remission of colorectal cancer (CRC) is still unachievable in the majority of patients by common fractionated radiotherapy, leaving risks of tumor metastasis and recurrence. Herein, clinical CRC samples demonstrated a difference in the phosphorylation of translation initiation factor eIF2α (p-eIF2α) and the activating transcription factor 4 (ATF4), whose increased expression by initial X-ray irradiation led to the resistance to subsequent radiotherapy. The underlying mechanism is studied in radio-resistant CT26 cells, revealing that the incomplete mitochondrial outer membrane permeabilization (iMOMP) triggered by X-ray irradiation is key for the elevated expression of p-eIF2α and ATF4, and therefore radio-resistance. This finding guided to discover that metformin and 2-DG are synergistic in reversing radio resistance by inhibiting p-eIF2α and ATF4. Liposomes loaded with metformin and 2-DG (M/D-Lipo) are thus prepared for enhancing fractionated radiotherapy of CRC, which achieved satisfactory therapeutic efficacy in both local and metastatic CRC tumors by reversing radio-resistance and preventing T lymphocyte exhaustion.

Metabolic Alteration Bridging the Prediabetic State and Colorectal Cancer

Prediabetes and colorectal cancer (CRC) represent compelling health burdens responsible for high mortality and morbidity rates, sharing several modifiable risk factors. It has been hypothesized that metabolic abnormalities linking prediabetes and CRC are hyperglycemia, hyperinsulinemia, and adipokines imbalance. The chronic stimulation related to these metabolic signatures can favor CRC onset and development, as well as negatively influence CRC prognosis. To date, the growing burden of prediabetes and CRC has generated a global interest in defining their epidemiological and molecular relationships. Therefore, a deeper knowledge of the metabolic impairment determinants is compelling to identify the pathological mechanisms promoting the onset of prediabetes and CRC. In this scenario, this review aims to provide a comprehensive overview on the metabolic alterations of prediabetes and CRC as well as an overview of recent preventive and therapeutic approaches for both diseases, focusing on the role of the metabolic state as a pivotal contributor to consider for the development of future preventive and therapeutic strategies.

Metabolic plasticity of T cell fate decision

ABSTRACT

The efficacy of adaptive immune responses in cancer treatment relies heavily on the state of the T cells. Upon antigen exposure, T cells undergo metabolic reprogramming, leading to the development of functional effectors or memory populations. However, within the tumor microenvironment (TME), metabolic stress impairs CD8 + T cell anti-tumor immunity, resulting in exhausted differentiation. Recent studies suggested that targeting T cell metabolism could offer promising therapeutic opportunities to enhance T cell immunotherapy. In this review, we provide a comprehensive summary of the intrinsic and extrinsic factors necessary for metabolic reprogramming during the development of effector and memory T cells in response to acute and chronic inflammatory conditions. Furthermore, we delved into the different metabolic switches that occur during T cell exhaustion, exploring how prolonged metabolic stress within the TME triggers alterations in cellular metabolism and the epigenetic landscape that contribute to T cell exhaustion, ultimately leading to a persistently exhausted state. Understanding the intricate relationship between T cell metabolism and cancer immunotherapy can lead to the development of novel approaches to improve the efficacy of T cell-based treatments against cancer.

ALYREF-JunD-SLC7A5 axis promotes pancreatic ductal adenocarcinoma progression through epitranscriptome-metabolism reprogramming and immune evasion

Pancreatic ductal adenocarcinoma (PDAC) is a kind of tumor lacking nutrients due to its poor vascularity and desmoplasia. Recent studies have shown that cancer cells might achieve growth advantage through epitranscriptome reprogramming. However, the role of m5C in PDAC was not fully understood. We found that Aly/REF export factor (ALYREF), a reader of m5C modification, was overexpressed in PDAC, and associated with bad prognosis. In addition, the ALYREF expression was negatively related to CD8+ T cells infiltration in clinical samples. ALYREF knockdown decreased tumor growth in vivo partly dependent of immunity. ALYREF silencing decreased SLC7A5 expression and subsequently inactivated mTORC1 pathway, resulting in decreased tumor proliferation. Mechanically, ALYREF specifically recognized m5C sites in JunD mRNA, maintained the stabilization of JunD mRNA and subsequently upregulated transcription of SLC7A5. Since SLC7A5 was a key transporter of large neutral amino acids (LNAAs), overexpression of SLC7A5 on tumor cells depleted amino acid in microenvironment and restricted CD8+ T cells function. Moreover, ALYREF-JunD-SLC7A5 axis was overexpressed and negatively related with survival through TMA assays. In conclusion, this research revealed the relationship between m5C modification, amino acid transportation and immune microenvironment. ALYREF might be a novel target for PDAC metabolic vulnerability and immune surveillance.

Metformin Attenuates Neutrophil Recruitment through the H3K18 Lactylation/Reactive Oxygen Species Pathway in Zebrafish

Beyond its well-established role in diabetes management, metformin has gained attention as a promising therapeutic for inflammation-related diseases, largely due to its antioxidant capabilities. However, the mechanistic underpinnings of this effect remain elusive. Using in vivo zebrafish models of inflammation, we explored the impact of metformin on neutrophil recruitment and the underlying mechanisms involved. Our data indicate that metformin reduces histone (H3K18) lactylation, leading to the decreased production of reactive oxygen species (ROS) and a muted neutrophil response to both caudal fin injury and otic vesicle inflammation. To investigate the precise mechanisms through which metformin modulates neutrophil migration via ROS and H3K18 lactylation, we meticulously established the correlation between metformin-induced suppression of H3K18 lactylation and ROS levels. Through supplementary experiments involving the restoration of lactate and ROS, our findings demonstrated that elevated levels of both lactate and ROS significantly promoted the inflammatory response in zebrafish. Collectively, our study illuminates previously unexplored avenues of metformin's antioxidant and anti-inflammatory actions through the downregulation of H3K18 lactylation and ROS production, highlighting the crucial role of epigenetic regulation in inflammation and pointing to metformin's potential in treating inflammation-associated conditions.