bims-tumime Biomed News
on Tumor microenvironment and metabolism
Issue of 2024–01–14
seven papers selected by
Alex Muir, University of Chicago



  1. bioRxiv. 2023 Dec 24. pii: 2023.12.24.573250. [Epub ahead of print]
      The tumor microenvironment is a determinant of cancer progression and therapeutic efficacy, with nutrient availability playing an important role. Although it is established that the local abundance of specific nutrients defines the metabolic parameters for tumor growth, the factors guiding nutrient availability in tumor compared to normal tissue and blood remain poorly understood. To define these factors in renal cell carcinoma (RCC), we performed quantitative metabolomic and comprehensive lipidomic analyses of tumor interstitial fluid (TIF), adjacent normal kidney interstitial fluid (KIF), and plasma samples collected from patients. TIF nutrient composition closely resembles KIF, suggesting that tissue-specific factors unrelated to the presence of cancer exert a stronger influence on nutrient levels than tumor-driven alterations. Notably, select metabolite changes consistent with known features of RCC metabolism are found in RCC TIF, while glucose levels in TIF are not depleted to levels that are lower than those found in KIF. These findings inform tissue nutrient dynamics in RCC, highlighting a dominant role of non-cancer driven tissue factors in shaping nutrient availability in these tumors.
    DOI:  https://doi.org/10.1101/2023.12.24.573250
  2. EMBO Rep. 2024 Jan 12.
      Tumor cells reprogram nutrient acquisition and metabolic pathways to meet their energetic, biosynthetic, and redox demands. Similarly, metabolic processes in immune cells support host immunity against cancer and determine differentiation and fate of leukocytes. Thus, metabolic deregulation and imbalance in immune cells within the tumor microenvironment have been reported to drive immune evasion and to compromise therapeutic outcomes. Interestingly, emerging evidence indicates that anti-tumor immunity could modulate tumor heterogeneity, aggressiveness, and metabolic reprogramming, suggesting that immunosurveillance can instruct cancer progression in multiple dimensions. This review summarizes our current understanding of how metabolic crosstalk within tumors affects immunogenicity of tumor cells and promotes cancer progression. Furthermore, we explain how defects in the metabolic cascade can contribute to developing dysfunctional immune responses against cancers and discuss the contribution of immunosurveillance to these defects as a feedback mechanism. Finally, we highlight ongoing clinical trials and new therapeutic strategies targeting cellular metabolism in cancer.
    Keywords:  Cancer Evolution; Immunoediting; Immunometabolism
    DOI:  https://doi.org/10.1038/s44319-023-00038-w
  3. Trends Endocrinol Metab. 2024 Jan 10. pii: S1043-2760(23)00250-3. [Epub ahead of print]
      Tumours are heterogeneous tissues containing diverse populations of cells and an abundant extracellular matrix (ECM). This tumour microenvironment prompts cancer cells to adapt their metabolism to survive and grow. Besides epigenetic factors, the metabolism of cancer cells is shaped by crosstalk with stromal cells and extracellular components. To date, most experimental models neglect the complexity of the tumour microenvironment and its relevance in regulating the dynamics of the metabolism in cancer. We discuss emerging strategies to model cellular and extracellular aspects of cancer metabolism. We highlight cancer models based on bioengineering, animal, and mathematical approaches to recreate cell-cell and cell-matrix interactions and patient-specific metabolism. Combining these approaches will improve our understanding of cancer metabolism and support the development of metabolism-targeting therapies.
    Keywords:  cancer metabolism; cancer models; mathematical models; tumour microenvironment
    DOI:  https://doi.org/10.1016/j.tem.2023.12.005
  4. Res Sq. 2023 Dec 20. pii: rs.3.rs-3664129. [Epub ahead of print]
      BACKGROUND Many tumors contain hypoxic microenvironments caused by inefficient tumor vascularization. Hypoxic tumors have been shown to resist conventional cancer therapies. Hypoxic cancer cells rely on glucose to meet their energetic and anabolic needs to fuel uncontrolled proliferation and metastasis. This glucose dependency is linked to a metabolic shift in response to hypoxic conditions. METHODS To leverage the glucose dependency of hypoxic tumor cells, we assessed the effects of a controlled reduction in systemic glucose by combining dietary carbohydrate restriction, using a ketogenic diet, with gluconeogenesis inhibition, using metformin, on two mouse models of triple-negative breast cancer (TNBC). RESULTS We confirmed that MET - 1 breast cancer cells require abnormally high glucose concentrations to survive in a hypoxic environment in vitro. Then, we showed that, compared to a ketogenic diet or metformin alone, animals treated with the combination regimen showed significantly lower tumor burden, higher tumor latency and slower tumor growth. As a result, lowering systemic glucose by this combined dietary and pharmacologic approach improved overall survival in our mouse model by 31 days, which is approximately equivalent to 3 human years. CONCLUSION This is the first preclinical study to demonstrate that reducing systemic glucose by combining a ketogenic diet and metformin significantly inhibits tumor proliferation and increases overall survival. Our findings suggest a possible treatment for a broad range of hypoxic and glycolytic tumor types, one that can also augment existing treatment options to improve patient outcomes.
    DOI:  https://doi.org/10.21203/rs.3.rs-3664129/v1
  5. J Exp Clin Cancer Res. 2024 Jan 13. 43(1): 19
      Ferroptosis, a novel form of cell death triggered by iron-dependent phospholipid peroxidation, presents significant therapeutic potential across diverse cancer types. Central to cellular metabolism, the metabolic pathways associated with ferroptosis are discernible in both cancerous and immune cells. This review begins by delving into the intricate reciprocal regulation of ferroptosis between cancer and immune cells. It subsequently details how factors within the tumor microenvironment (TME) such as nutrient scarcity, hypoxia, and cellular density modulate ferroptosis sensitivity. We conclude by offering a comprehensive examination of distinct immunophenotypes and environmental and metabolic targets geared towards enhancing ferroptosis responsiveness within the TME. In sum, tailoring precise ferroptosis interventions and combination strategies to suit the unique TME of specific cancers may herald improved patient outcomes.
    Keywords:  Cellular metabolism; Ferroptosis; Tumor Microenvironment; Tumor immunity
    DOI:  https://doi.org/10.1186/s13046-023-02925-5
  6. bioRxiv. 2023 Dec 23. pii: 2023.12.22.573073. [Epub ahead of print]
      Breast-cancer brain metastasis (BCBM) poses a significant clinical challenge, resulting in an end-stage diagnosis and hindered by limited therapeutic options. The blood-brain barrier (BBB) acts as an anatomical and physiological hurdle for therapeutic compounds, restricting the effective delivery of therapies to the brain. In order to grow and survive in a nutrient-poor environment, tumors in the brain must adapt to their metabolic needs, becoming highly dependent on acetate. These tumors rely on the conversion of acetate to acetyl-CoA by the enzyme Acetyl-CoA synthetase 2 (ACSS2), a key metabolic enzyme involved in regulating fatty acid synthesis and protein acetylation in tumor cells. ACSS2 has emerged as a crucial enzyme required for the growth of tumors in the brain. Here, we utilized a computational pipeline, combining pharmacophore-based shape screen methodology with ADME property predictions to identify novel brain-permeable ACSS2 inhibitors. From a small molecule library, this approach identified 30 potential ACSS2 binders, from which two candidates, AD-5584 and AD-8007, were validated for their binding affinity, predicted metabolic stability, and, notably, their ability to traverse the BBB. We show that treatment of BCBM cells, MDA-MB-231BR, with AD-5584 and AD-8007 leads to a significant reduction in lipid storage, reduction in colony formation, and increase in cell death in vitro . Utilizing an ex vivo orthotopic brain-slice tumor model, we show that treatment with AD-8007 and AD-5584 significantly reduces tumor size and synergizes with radiation in blocking BCBM tumor growth ex vivo. Importantly, we show that following intraperitoneal injections with AD-5584 and AD-8007, we can detect these compounds in the brain, confirming their BBB permeability. Thus, we have identified and validated novel ACSS2 inhibitor candidates for further drug development and optimization as agents for treating patients with breast cancer brain metastasis.
    DOI:  https://doi.org/10.1101/2023.12.22.573073
  7. Nat Commun. 2024 Jan 11. 15(1): 451
      Immune cells must adapt to different environments during the course of an immune response. Here we study the adaptation of CD8+ T cells to the intestinal microenvironment and how this process shapes the establishment of the CD8+ T cell pool. CD8+ T cells progressively remodel their transcriptome and surface phenotype as they enter the gut wall, and downregulate expression of mitochondrial genes. Human and mouse intestinal CD8+ T cells have reduced mitochondrial mass, but maintain a viable energy balance to sustain their function. We find that the intestinal microenvironment is rich in prostaglandin E2 (PGE2), which drives mitochondrial depolarization in CD8+ T cells. Consequently, these cells engage autophagy to clear depolarized mitochondria, and enhance glutathione synthesis to scavenge reactive oxygen species (ROS) that result from mitochondrial depolarization. Impairing PGE2 sensing promotes CD8+ T cell accumulation in the gut, while tampering with autophagy and glutathione negatively impacts the T cell pool. Thus, a PGE2-autophagy-glutathione axis defines the metabolic adaptation of CD8+ T cells to the intestinal microenvironment, to ultimately influence the T cell pool.
    DOI:  https://doi.org/10.1038/s41467-024-44689-2