The role of glycolysis and lactate in the induction of tumor-associated macrophages immunosuppressive phenotype

Depressive Disorder Affects TME and Hormonal Changes Promoting Tumour Deterioration Development

Cancer patients often suffer from depression, the presence of which promotes the deterioration of the cancer patient's condition and thus affects the patient's survival. However, the exact mechanisms underlying the relationship between depression and tumour progression remain unclear, and this complexity involves multi-system and multi-level interactions, with several key challenges remaining in current research. First, the extreme complexity of biological systems. Depression and tumors involve multiple pathways such as neuroendocrine, immune system, and metabolism, respectively, and there are nonlinear interactions between these pathways (e.g., HPA axis activation affects both immunosuppression and tumor angiogenesis), so it is difficult to isolate the predominant role of a single mechanism, and there are feedback loops (e.g., inflammatory factors (e.g., IL-6) can both induce depressive symptoms and promote tumor growth) form a "feedback loop between depression and tumors" that makes it difficult to determine the direction of causality. Second, the potential blind spot of mechanism research. There is insufficient direct evidence for the brain-tumor axis, and it is known that the vagus nerve or sympathetic nerves can directly modulate the tumor microenvironment (TME) (e.g., via β-adrenergic receptors), but there is a lack of technical support for in vivo imaging on how the CNS remotely affects tumors through the neural circuits; whereas depression-associated disturbances of the intestinal flora or in certain stages of tumor development (e.g., metastatic) or specific microenvironments (e.g., areas of hyper-infiltrating T-cells) may have long-term effects on the tumors, but such changes are difficult to capture in short-term experiments and cannot be precisely temporally resolved by existing technologies. However, there are limitations in current research methods. Existing studies have relied on mouse models of chronic stress (e.g., chronic unpredictable stress), but the "depression-like behaviour" of mice is fundamentally different from the clinical manifestations of depression in humans, and the TME (e.g., immune composition) is different from that of humans. Finally, for patients with cancer-associated depression, clinical treatment is usually a two-pronged strategy, but the combination of anticancer and antidepressant drugs has limitations, such as drug-drug interactions, safety issues, and the challenge of individualised treatment in clinical practice. Therefore, by elucidating the relationship between depression and tumour bidirectional effects, this review relatively clarifies how depression affects TME to promote tumour progression by influencing changes in immunosuppression, hormonal changes, glutamate/glutamate receptors, and intestinal flora. Further, some potential therapeutic strategies are proposed for the clinical treatment of this group of patients through the above pathological mechanism; at the same time, it was found that antidepressant drugs have potential antitumor activity, and their dual pharmacological effects may provide synergistic therapeutic benefits for patients with cancer-associated depressive disorders. This finding not only expands the choice of drugs for tumour therapy but also provides a new theoretical basis for comprehensive treatment strategies in the field of psycho-oncology.

Lactate released by lung adenocarcinoma (LUAD) cells promotes M2 macrophage polarization via the GPR132/cAMP/PKA pathway

BACKGROUND

Increasing evidence suggests that lactate is an essential compound in the tumor microenvironment, and especially for macrophage cells. However, the mechanism by which lactate affects macrophages remains unclear.

OBJECTIVE

This study investigated whether and how lactate affects macrophage polarization in lung adenocarcinoma (LUAD).

METHODS

Clinical samples of LUAD and paracancerous tissue were obtained for evaluation of lactate dehydrogenase A (LDHA) expression. LUAD cell lines and THP-1 induced macrophages were used in this study. Quantitative real-time PCR (QPCR), western blotting, and immunohistochemical (IHC) staining were performed to detect gene expression. Flow cytometry and ELISA assays were used to detect the levels of M1 macrophage and M2 macrophage biomarkers.

RESULTS

LDHA was highly expressed in the LUAD tissues. Culture medium supernatants derived from LUAD cells (CM) promoted macrophage M2 polarization, and lactate levels were elevated in the CM. Inhibition of LDHA in LUAD cells decreased lactate levels and suppressed M2 macrophage polarization. Moreover, overexpression of GPR132 in macrophages promoted, while GPR132 knockdown in macrophages suppressed M2 macrophage polarization and cAMP (Cyclic Adenosine 3',5'-Monophosphate)/PKA (Protein Kinase) pathway activation induced by lactate. The effect of GPR132 overexpression was reversed by a PKA inhibitor (H-89).

CONCLUSION

Collectively, our results confirmed that lactate released by LUAD cells promoted M2 macrophage polarization via the GPR132/cAMP/PKA pathway.

Unraveling the triad of immunotherapy, tumor microenvironment, and skeletal muscle biomechanics in oncology

The intricate interaction between skeletal muscle biomechanics, the tumor microenvironment, and immunotherapy constitutes a pivotal research focus oncology. This work provides a comprehensive review of methodologies for evaluating skeletal muscle biomechanics, including handheld dynamometry, advanced imaging techniques, electrical impedance myography, elastography, and single-fiber experiments to assess muscle quality and performance. Furthermore, it elucidates the mechanisms, applications, and limitations of various immunotherapy modalities, including immune checkpoint inhibitors, adoptive cell therapy, cancer vaccines, and combined chemoimmunotherapy, while examining their effects on skeletal muscle function and systemic immune responses. Key findings indicate that although immunotherapy is effective in augmenting antitumor immunity, it frequently induces muscle-related adverse effects such as weakness, fatigue, or damage, primarily mediated by cytokine release and immune activation. This work underscores the significance of immune niches within the tumor microenvironment in influencing treatment outcomes and proposes strategies to optimize therapy through personalized regimens and combinatorial approaches. This review highlights the need for further research on the formation of immune niches and interactions muscle-tumor. Our work is crucial for advancing the efficacy of immunotherapy, reducing adverse effects, and ultimately improving survival rates and quality of life of patients with cancer.

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

BACKGROUND

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

AIM OF REVIEW

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

KEY SCIENTIFIC CONCEPTS OF REVIEW

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

Anti-Tumor Strategies Targeting Nutritional Deprivation: Challenges and Opportunities

Higher and richer nutrient requirements are typical features that distinguish tumor cells from AU: cells, ensuring adequate substrates and energy sources for tumor cell proliferation and migration. Therefore, nutrient deprivation strategies based on targeted technologies can induce impaired cell viability in tumor cells, which are more sensitive than normal cells. In this review, nutrients that are required by tumor cells and related metabolic pathways are introduced, and anti-tumor strategies developed to target nutrient deprivation are described. In addition to tumor cells, the nutritional and metabolic characteristics of other cells in the tumor microenvironment (including macrophages, neutrophils, natural killer cells, T cells, and cancer-associated fibroblasts) and related new anti-tumor strategies are also summarized. In conclusion, recent advances in anti-tumor strategies targeting nutrient blockade are reviewed, and the challenges and prospects of these anti-tumor strategies are discussed, which are of theoretical significance for optimizing the clinical application of tumor nutrition deprivation strategies.

Subcellular Organelle Targeting as a Novel Approach to Combat Tumor Metastasis

Tumor metastasis, the spread of cancer cells from the primary site to distant organs, remains a formidable challenge in oncology. Central to this process is the involvement of subcellular organelles, which undergo significant functional and structural changes during metastasis. Targeting these specific organelles offers a promising avenue for enhanced drug delivery and metastasis therapeutic efficacy. This precision increases the potency and reduces potential off-target effects. Moreover, by understanding the role of each organelle in metastasis, treatments can be designed to disrupt the metastatic process at multiple stages, from cell migration to the establishment of secondary tumors. This review delves deeply into tumor metastasis processes and their connection with subcellular organelles. In order to target these organelles, biomembranes, cell-penetrating peptides, localization signal peptides, aptamers, specific small molecules, and various other strategies have been developed. In this review, we will elucidate targeting delivery strategies for each subcellular organelle and look forward to prospects in this domain.

The role of macrophages in chronic pain

Chronic pain typically lasts or recurs for more than three months and is an unpleasant sensory and emotional experience, including neuropathic pain, long-term tissue damage, tumors, and viral or bacterial infections.The unpleasantness associated with pain affects the basic life of patients and has become a truly global problem. Macrophages, a powerful immune effector cell whose functional plasticity leads to polarization into different subtypes and opposite effects in different environments, are also indispensable in the development of pain.In recent years, there has been an increasing number of studies on the effects of macrophages on pain, and there are multiple pathways that regulate macrophage polarization, including lipopolysaccharide induction and IL-4/IL-13 stimulation.In addition, pathways involving macrophages and macrophage polarization have been found to have an exacerbating or mitigating role in the progression of chronic pain, with M1 macrophages generally exacerbating pain progression and M2 macrophages mitigating pain progression.Therefore, modulating macrophage polarization holds great promise as an intervention in chronic pain. In this paper, we synthesize multiple macrophage pathways as well as mechanisms affecting their pain processes in the context of different types of chronic pain, providing new avenues for chronic pain relief.

Multi-omics-driven discovery of invasive patterns and treatment strategies in CA19-9 positive intrahepatic cholangiocarcinoma

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) is a malignant tumor with a poor prognosis, predominantly CA19-9 positive. High CA19-9 levels correlate with increased aggressiveness and worse outcomes. This study employs multi-omics analysis to reveal molecular features and identify therapeutic targets of CA19-9 positive ICC, aiming to support individualized treatment.

METHODS

Data from seven clinical cohorts, two whole-exome sequencing cohorts, six RNA sequencing/microarray cohorts, one proteomic cohort, 20 single-cell RNA sequencing samples, and one spatial transcriptome sample were analyzed. Key findings were validated on tissue microarrays from 52 ICC samples.

RESULTS

CA19-9 positive ICC exhibited poorer OS (median 24.1 v.s. 51.5 months) and RFS (median 11.7 v.s. 28.2 months) compared to negative group (all P < 0.05). Genomic analysis revealed a higher KRAS mutation frequency in the positive group and a greater prevalence of IDH1/2 mutations in the negative group (all P < 0.05). Transcriptomic analysis indicated upregulated glycolysis pathways in CA19-9 positive ICC. Single-cell analysis identified specific glycolysis-related cell subclusters associated with poor prognosis, including Epi_SLC2A1, CAF_VEGFA, and Mph_SPP1. Higher hypoxia in the CA19-9 positive group led to metabolic reprogramming and promoted these cells' formation. These cells formed interactive communities promoting epithelial-mesenchymal transition (EMT) and angiogenesis. Drug sensitivity analysis identified six potential therapeutic drugs.

CONCLUSIONS

This study systematically elucidated the clinical, genomic, transcriptomic, and immune features of CA19-9 positive ICC. It reveals glycolysis-associated cellular communities and their cancer-promoting mechanisms, enhancing our understanding of ICC and laying the groundwork for individualized therapeutic strategies.

Unveiling the contribution of tumor-associated macrophages in driving epithelial-mesenchymal transition: a review of mechanisms and therapeutic Strategies

Tumor-associated macrophages (TAMs), fundamental constituents of the tumor microenvironment (TME), significantly influence cancer development, primarily by promoting epithelial-mesenchymal transition (EMT). EMT endows cancer cells with increased motility, invasiveness, and resistance to therapies, marking a pivotal juncture in cancer progression. The review begins with a detailed exposition on the origins of TAMs and their functional heterogeneity, providing a foundational understanding of TAM characteristics. Next, it delves into the specific molecular mechanisms through which TAMs induce EMT, including cytokines, chemokines and stromal cross-talking. Following this, the review explores TAM-induced EMT features in select cancer types with notable EMT characteristics, highlighting recent insights and the impact of TAMs on cancer progression. Finally, the review concludes with a discussion of potential therapeutic targets and strategies aimed at mitigating TAM infiltration and disrupting the EMT signaling network, thereby underscoring the potential of emerging treatments to combat TAM-mediated EMT in cancer. This comprehensive analysis reaffirms the necessity for continued exploration into TAMs' regulatory roles within cancer biology to refine therapeutic approaches and improve patient outcomes.

Enhanced Osteosarcoma Immunotherapy via CaCO3 Nanoparticles: Remodeling Tumor Acidic and Immune Microenvironment for Photodynamic Therapy

Osteosarcoma (OS) is a "cold" tumor enriched in noninflammatory M2 phenotype tumor-associated macrophages (TAMs), which limits the efficacy of immunotherapy. The acidic tumor microenvironment (TME), generated by factors such as excess hydrogen (H+) ions and high lactate levels, activates immunosuppressive cells, further promoting a suppressive tumor immune microenvironment (TIME). Therefore, a multitarget synergistic combination strategy that neutralizes the acidic TME and reprograms TAMs can be beneficial for OS therapy. Here, a calcium carbonate (CaCO3)/polydopamine (PDA)-based nanosystem (A-NPs@(SHK+Ce6)) is developed. CaCO3 nanoparticles are used to neutralize H+ ions and alleviate the suppressive TIME, and the loaded SHK not only synergizes with photodynamic therapy (PDT) but also inhibits lactate production, further reversing the acidic TME and repolarizing TAMs to consequently lead to enhanced PDT-induced tumor suppression and comprehensive beneficial effects on antitumor immune responses. Importantly, A-NPs@(SHK+Ce6), in combination with programmed cell death protein 1 (PD-1) checkpoint blockade, shows a remarkable ability to eliminate distant tumors and promote long-term immune memory function to protect against rechallenged tumors. This work presents a novel multiple-component combination strategy that coregulates the acidic TME and TAM polarization to reprogram the TIME.

Tumor-associated macrophages derived exosomes; from pathogenesis to therapeutic opportunities

Tumor-associated macrophages (TAMs) exert profound influences on cancer progression, orchestrating a dynamic interplay within the tumor microenvironment. Recent attention has focused on the role of TAM-derived exosomes, small extracellular vesicles containing bioactive molecules, in mediating this intricate communication. This review comprehensively synthesizes current knowledge, emphasizing the diverse functions of TAM-derived exosomes across various cancer types. The review delves into the impact of TAM-derived exosomes on fundamental cancer hallmarks, elucidating their involvement in promoting cancer cell proliferation, migration, invasion, and apoptosis evasion. By dissecting the molecular cargo encapsulated within these exosomes, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and proteins, the review uncovers key regulatory mechanisms governing these effects. Noteworthy miRNAs, such as miR-155, miR-196a-5p, and miR-221-3p, are highlighted for their pivotal roles in mediating TAM-derived exosomal communication and influencing downstream targets. Moreover, the review explores the impact of TAM-derived exosomes on the immune microenvironment, particularly their ability to modulate immune cell function and foster immune evasion. The discussion encompasses the regulation of programmed cell death ligand 1 (PD-L1) expression and subsequent impairment of CD8 + T cell activity, unraveling the immunosuppressive effects of TAM-derived exosomes. With an eye toward clinical implications, the review underscores the potential of TAM-derived exosomes as diagnostic markers and therapeutic targets. Their involvement in cancer progression, metastasis, and therapy resistance positions TAM-derived exosomes as key players in reshaping treatment strategies. Finally, the review outlines future directions, proposing avenues for targeted therapies aimed at disrupting TAM-derived exosomal functions and redefining the tumor microenvironment.

Single-cell and spatial transcriptomics reveal a high glycolysis B cell and tumor-associated macrophages cluster correlated with poor prognosis and exhausted immune microenvironment in diffuse large B-cell lymphoma

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous malignancy characterized by varied responses to treatment and prognoses. Understanding the metabolic characteristics driving DLBCL progression is crucial for developing personalized therapies.

METHODS

This study utilized multiple omics technologies including single-cell transcriptomics (n = 5), bulk transcriptomics (n = 966), spatial transcriptomics (n = 10), immunohistochemistry (n = 34), multiple immunofluorescence (n = 20) and to elucidate the metabolic features of highly malignant DLBCL cells and tumor-associated macrophages (TAMs), along with their associated tumor microenvironment. Metabolic pathway analysis facilitated by scMetabolism, and integrated analysis via hdWGCNA, identified glycolysis genes correlating with malignancy, and the prognostic value of glycolysis genes (STMN1, ENO1, PKM, and CDK1) and TAMs were verified.

RESULTS

High-glycolysis malignant DLBCL tissues exhibited an immunosuppressive microenvironment characterized by abundant IFN_TAMs (CD68+CXCL10+PD-L1+) and diminished CD8+ T cell infiltration. Glycolysis genes were positively correlated with malignancy degree. IFN_TAMs exhibited high glycolysis activity and closely communicating with high-malignancy DLBCL cells identified within datasets. The glycolysis score, evaluated by seven genes, emerged as an independent prognostic factor (HR = 1.796, 95% CI: 1.077-2.995, p = 0.025 and HR = 2.631, 95% CI: 1.207-5.735, p = 0.015) along with IFN_TAMs were positively correlated with poor survival (p < 0.05) in DLBCL. Immunohistochemical validation of glycolysis markers (STMN1, ENO1, PKM, and CDK1) and multiple immunofluorescence validation of IFN_TAMs underscored their prognostic value (p < 0.05) in DLBCL.

CONCLUSIONS

This study underscores the significance of glycolysis in tumor progression and modulation of the immune microenvironment. The identified glycolysis genes and IFN_TAMs represent potential prognostic markers and therapeutic targets in DLBCL.

Triple Negative Breast Cancer: Molecular Subtype-Specific Immune Landscapes with Therapeutic Implications

Triple Negative Breast Cancer (TNBC) is characterized by distinct molecular subtypes with unique biological and clinical features. This systematic review aimed to identify articles examining the differences in the tumor immune microenvironment (TIME) across different TNBC molecular subtypes. Six studies meeting inclusion criteria were analyzed, utilizing gene expression profiling and bioinformatic analyses to classify TNBC samples into molecular subtypes, as well as immunohistochemistry and cell deconvolution methods to characterize the TIME. Results revealed significant heterogeneity in immune cell composition among TNBC subtypes, with the immunomodulatory (IM) subtype demonstrating robust immune infiltration, composed mainly of adaptive immune cells along with an increased density of CTLA-4+ and PD-1+ TILs, high PD-L1 tumor cell expression, and upregulation of FOXP3+ Tregs. A more immunosuppressive TIME with a predominance of innate immune cells and lower levels of tumor-infiltrating lymphocytes (TILs) was observed in luminal androgen receptor (LAR) tumors. In mesenchymal stem-like (MSL) tumors, the TIME was mainly composed of innate immune cells, with a high number of M2 tumor-associated macrophages (TAMs), while the BL and M tumors displayed poor adaptive and innate immune responses, indicating an "immune-cold" phenotype. Differential activation of signaling pathways, genomic diversity, and metabolic reprogramming were identified as contributors to TIME heterogeneity. Understanding this interplay is crucial for tailoring therapeutic strategies, especially regarding immunotherapy.

Siglec9 + tumor-associated macrophages predict prognosis and therapeutic vulnerability in patients with colon cancer

BACKGROUND

Siglec9 has been identified as an immune checkpoint molecule on tumor-associated macrophages (TAMs). Nevertheless, the expression profile and clinical significance of Siglec9 + TAMs in colon cancer (CC) are still not fully understood.

METHODS

Two clinical cohorts from distinct medical centers were retrospectively enrolled. Immunohistochemistry and immunofluorescence were conducted to evaluate the infiltration of immune cells. Single-cell RNA sequencing and flow cytometry were utilized to identify the impact of Siglec9 + TAMs on the tumor immune environment, which was subsequently validated through bioinformatics analysis of the TCGA database. Prognosis and the benefit of adjuvant chemotherapy (ACT) were also evaluated using Cox regression analysis and the Kaplan-Meier method.

RESULTS

High infiltration of Siglec9 + TAMs was associated with worse prognosis and better benefit from 6-month ACT. Siglec9 + TAMs contributed to immunoevasion by promoting the infiltration of immunosuppressive cells and the dysfunction process of CD8 + T cells. Additionally, high infiltration of Siglec9 + TAMs was associated with the mesenchymal-featured subtype and overexpression of the VEGF signaling pathway, which was validated by the strongest communication between Siglec9 + TAMs and vascular endothelial cells.

CONCLUSIONS

Siglec9 + TAMs may serve as a biomarker for prognosis and response to ACT in CC. Furthermore, the immunoevasive contexture and angiogenesis stimulated by Siglec9 + TAMs suggest potential treatment combinations for CC patients.

PARP14 Contributes to the Development of the Tumor-Associated Macrophage Phenotype

Cancers reprogram macrophages (MΦs) to a tumor-growth-promoting TAM (tumor-associated MΦ) phenotype that is similar to the anti-inflammatory M2 phenotype. Poly(ADP-ribose) polymerase (PARP) enzymes regulate various aspects of MΦ biology, but their role in the development of TAM phenotype has not yet been investigated. Here, we show that the multispectral PARP inhibitor (PARPi) PJ34 and the PARP14 specific inhibitor MCD113 suppress the expression of M2 marker genes in IL-4-polarized primary murine MΦs, in THP-1 monocytic human MΦs, and in primary human monocyte-derived MΦs. MΦs isolated from PARP14 knockout mice showed a limited ability to differentiate to M2 cells. In a murine model of TAM polarization (4T1 breast carcinoma cell supernatant transfer to primary MΦs) and in a human TAM model (spheroids formed from JIMT-1 breast carcinoma cells and THP-1-MΦs), both PARPis and the PARP14 KO phenotype caused weaker TAM polarization. Increased JIMT-1 cell apoptosis in co-culture spheroids treated with PARPis suggested reduced functional TAM reprogramming. Protein profiling arrays identified lipocalin-2, macrophage migration inhibitory factor, and plasminogen activator inhibitor-1 as potential (ADP-ribosyl)ation-dependent mediators of TAM differentiation. Our data suggest that PARP14 inhibition might be a viable anticancer strategy with a potential to boost anticancer immune responses by reprogramming TAMs.

Formaldehyde promotes tumor-associated macrophage polarizations and functions through induction of HIF-1α-mediated glycolysis

Formaldehyde (FA) exposure has been positively correlated with many diseases including various types of cancers. However, the mechanisms of FA-related carcinogenesis are still unclear. Tumor-associated macrophages (TAMs) are the most abundant immune cells in tumor microenvironment, which is a heterogeneous population consist of both pro-inflammatory (M1) and immunosuppressive (M2) cells. TAMs are deeply involved in tumor development and progression. Our previous studies demonstrated that FA enhanced M1 polarization of macrophages through induction of HIF-1α-mediated glycolysis. To examine if TAM polarizations are also potentiated by FA, BALB/c nude mice were inoculated with A549 cells to develop subcutaneous tumors and exposed to 2.0 mg/m3 FA for 14 days. Significant increases of both M1 and M2 polarizations of TAMs were observed in tumor tissues of FA-exposed mice. After confirmation of the potentiation effects in RAW264.7 and THP-1-derived in vitro TAM models, FA at 25 and 50 μM was found to enhance TAM immunosuppressive functions and glycolytic metabolism. In addition, FA-induced glycolysis in TAMs was reversed by a specific HIF-1α inhibitor PX-478 at 5 μM, and suppression of glycolytic metabolism with a glucose analog 2-DG at 1 mM also alleviated FA-potentiated TAM functions, which indicated that FA induced TAM polarizations through the upregulation of HIF-1α-mediated glycolysis. These results illustrated a potential carcinogenic mechanism of FA through metabolic disturbance of tumor immunity, which could be utilized to develop preventative or therapeutic agents for FA-induced carcinogenesis and immune disorders.

The transcription factor ELF4 alleviates inflammatory bowel disease by activating IL1RN transcription, suppressing inflammatory TH17 cell activity, and inducing macrophage M2 polarization

Background

Inflammatory bowel disease (IBD) is a chronic immune-mediated disorder affecting millions worldwide. Due to the complexity of its pathogenesis, the treatment options for IBD are limited. This study focuses on ELF4, a member of the ETS transcription factor family, as a target to elucidate its role in IBD and investigate its mechanism of action in alleviating IBD symptoms by activating IL1RN transcription to suppress the activity of inflammatory TH17 cells.

Methods

Using the GEO database, this study examined LPS-induced intestinal inflammatory genes and their regulation mechanisms. We examined the colon length of LPS-treated mice and derived the Disease Activity Index (DAI). H&E staining, ELISA, and flow cytometry were used to detect mice colon tissue damage, inflammatory factor levels in mouse serum, mouse macrophage types and inflammatory TH17 cell activity. RT-qPCR and Western blot detected ELF4, IL1RN, M1, and M2 polarization markers. In Vitro, using dual-luciferase and ChIP assays, we tested mouse bone marrow-derived macrophages (BMDMs) and mouse intestinal epithelial cells for IL1RN promoter activity and ELF4 enrichment.

Results

Bioinformatics showed that LPS-induced colitis animals have reduced ELF4 expression in their colon tissue. In vivo tests confirmed reduced ELF4 expression in mice with LPS-induced colitis. ELF4 overexpression reduced mouse intestinal inflammation. ELF4 activated IL1RN transcription in bioinformatics and in vitro tests. ELF4 promoted IL1RN transcription and macrophage M2 polarization to limit intestinal epithelial cell death and inflammation and reduce mouse intestinal inflammation in vitro. ELF4 also reduced the Th17/Treg ratio by increasing IL1RN transcription.

Conclusion

ELF4 activates IL1RN transcription, suppresses inflammatory TH17 cells, and induces macrophage M2 polarization to treat IBD.

A feed-forward loop based on aerobic glycolysis and TGF-β between tumor-associated macrophages and bladder cancer cells promoted malignant progression and immune escape

PURPOSE

Immunotherapy with programmed cell death 1/ligand 1 (PD-1/PD-L1) checkpoint inhibitors has revolutionized the systemic treatment of solid tumors, including bladder cancer. Previous studies have shown that enhanced glycolysis, tumor-associated macrophage (TAM) infiltration, and TGF-β secretion in the tumor microenvironment (TME) are closely related to PD-1/PD-L1 inhibitor immunotherapy resistance. However, the potential mechanism of their interaction in bladder cancer has not been fully uncovered.

METHODS

By coculturing bladder cancer cells and TAMs, we studied the relationship and interaction mechanism between tumor cell glycolysis, TAM functional remodeling, TGF-β positive feedback secretion, and PD-L1 mRNA m6A methylation in the bladder cancer microenvironment.

RESULTS

Bioinformatics analysis and IHC staining found a close correlation between tumor glycolysis, M2 TAM infiltration, and the prognosis of bladder cancer patients. In Vitro experiments demonstrated that bladder cancer cells could re-educate M2 TAMs through lactate and promote TGF-β secretion via the HIF-1α signaling pathway. Reciprocally, in vitro, and in vivo experiments validated that M2 TAMs could promote glycolysis in bladder cancer cells by TGF-β via the Smad2/3 signaling pathways. Furthermore, M2 TAMs could also promote CSCs and EMT of bladder cancer cells. More importantly, we found M2 TAMs enhance PD-L1 mRNA m6A methylation by promoting METLL3 expression in bladder cancer via the TGF-β/Smad2/3 pathway in the TME.

CONCLUSIONS

Our study highlights a feed-forward loop based on aerobic glycolysis and TGF-β between M2 TAMs and bladder cancer cells, which may be a potential mechanism of malignant progression and immunotherapy resistance in bladder cancer.

Overexpression of miR-4669 Enhances Tumor Aggressiveness and Generates an Immunosuppressive Tumor Microenvironment in Hepatocellular Carcinoma: Its Clinical Value as a Predictive Biomarker

Accumulating evidence suggests the involvement of tumor-derived exosomes in the development and recurrence of hepatocellular carcinoma (HCC). We previously identified miR-4669 as a highly expressed microRNA in circulating exosomes obtained from patients with post-transplant HCC recurrence. This study aimed to explore how overexpression of miR-4669 affects HCC development and recurrence. The impact of miR-4669 overexpression in Hep3B cells on tumor cell behavior and the tumor microenvironment was evaluated in vitro. In addition, the clinical value of exosomal miR-4669 for the prediction of treatment response to HCC downstaging therapies and following post-transplant HCC recurrence was explored. Overexpression of miR-4669 enhanced migration ability and led to acquired sorafenib resistance with an elevation of sirtuin 1 and long noncoding RNA associated with microvascular invasion. Active release of tumor-derived exosomes and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) contributed to generating an immunosuppressive tumor microenvironment through the induction of M2 macrophage polarization. The retrospective analysis demonstrated the clinical value of exosomal miR-4669 for predicting treatment response to HCC downstaging therapies and for risk assessment of post-transplant HCC recurrence. In summary, the present data demonstrate the impact of exosomal miR-4669 on HCC recurrence through the enhancement of tumor aggressiveness and generation of an immunosuppressive tumor microenvironment.