1,720,991 research outputs found
The influence of fatty acid metabolism on T cell function in lung cancer
Full text linkThe tumor microenvironment (TME) is a complex ecosystem, encompassing a variety of cellular and non-cellular elements surrounding and interacting with cancer cells, overall promoting tumor growth, immune evasion, and therapy resistance. In the context of solid tumors, factors, such as hypoxia, nutritional competition, increased stress responses, glucose demand, and PD-1 signals strongly influence metabolic alterations in the TME, highly contributing to the maintenance of a tumor-supportive and immune-suppressive milieu. Cancer cell-induced metabolic alterations partly result in an increased fatty acid (FA) metabolism within the TME, which strongly favors the recruitment of immune-suppressive M2 macrophages and myeloid-derived suppressor cells, crucial contributors to T-cell exhaustion, tumor exclusion, and decreased effector functions. The drastic pro-tumoral changes induced by the tumor metabolic rewiring result in signaling loops that support tumor progression and metastatic spreading, and negatively impact therapy efficacy. As tumor- and immune metabolism are increasingly gaining attention due to their potential therapeutic implications, we discuss the effects of altered lipid metabolism on tumor progression, immune response, and therapeutic efficacy in the context of lung cancer. In particular, we focus our analysis on the tumor-induced metabolic alterations experienced by T lymphocytes and the possible strategies to overcome immunotherapy resistance by targeting specific metabolic pathways in T cells
Glutamine Synthetase: Localization Dictates Outcome
Full text linkGlutamine synthetase (GS) is the adenosine triphosphate (ATP)-dependent enzyme that catalyses the synthesis of glutamine by condensing ammonium to glutamate. In the circulatory system, glutamine carries ammonia from muscle and brain to the kidney and liver. In brain reduction of GS activity has been suggested as a mechanism mediating neurotoxicity in neurodegenerative disorders. In cancer, the delicate balance between glutamine synthesis and catabolism is a critical event. In vitro evidence, confirmed in vivo in some cases, suggests that reduced GS activity in cancer cells associates with a more invasive and aggressive phenotype. However, GS is known to be highly expressed in cells of the tumor microenvironment, such as fibroblasts, adipocytes and immune cells, and their ability to synthesize glutamine is responsible for the acquisition of protumoral phenotypes. This has opened a new window into the complex scenario of the tumor microenvironment, in which the balance of glutamine consumption versus glutamine synthesis influences cellular function. Since GS expression responds to glutamine starvation, a lower glutamine synthesizing power due to the absence of GS in cancer cells might apply a metabolic pressure on stromal cells. This event might push stroma towards a GS-high/protumoral phenotype. When referred to stromal cells, GS expression might acquire a 'bad' significance to the point that GS inhibition might be considered a conceivable strategy against cancer metastasis
Editorial: Metabolism Meets Function: Untangling the Cross-Talk Between Signaling and Metabolism
Full text linkTumor metabolism is a long established field in cancer biology, as the seminal findings of Otto Warburg date back to the 1920s. Since then, the discovery that oncogenes, besides promoting the Warburg effect, modulate anabolic pathways, has prompted scientists to re-evaluate the role that tumor metabolism plays in the neoplastic process. Today, metabolic reprogramming of neoplastic cells is considered a hallmark of cancer, with the discovery that flexibility in the acquisition of various cellular characteristics is supported by specific metabolic pathways. Clinical and pharmacological advances, for example the application of FDG-PET in the clinical setting (1) and the development of novel pharmacological strategies based on antimetabolites (2), provide further support and validation of the role of metabolism in cancer. Here, we present a collection of works with the aim of bringing together work from a variety of scientists across the field of tumor metabolism toward an understanding of how different metabolic pathways are activated in neoplastic and surrounding cells, the mechanisms linking altered metabolism to tumorigenesis and the potential for pharmacological applications
ATP-citrate lyase is essential for macrophage inflammatory response
Full text linkGrowing evidence suggests that energy metabolism and inflammation are closely linked and that
cross-talk between these processes is fundamental to the pathogenesis of many human diseases.
However, the molecular mechanisms underlying these observations are still poorly understood. Here
we describe the key role of ATP-citrate lyase (ACLY) in inflammation. We find that ACLY mRNA and pro-
tein levels markedly and quickly increase in activated macrophages. Importantly, ACLY activity inhibition
as well as ACLY gene silencing lead to reduced nitric oxide, reactive oxygen species and prostaglandin E2
inflammatory mediators. In conclusion, we present a direct role for ACLY in macrophage inflammatory
metabolism
MEF2C exon α: role in gene activation and differentiation
Full text linkMyocyte enhancer factor 2C (MEF2C) belongs to theMEF2 transcription factors. All products ofMEF2 genes have
a common amino-terminal DNA binding and dimerization domain. All four vertebrateMEF2 gene transcripts are
also alternatively spliced. In the present study we identify two novel MEF2C splice variants, named VP and VP2.
These variants are generated by the skipping of exon α. The identified α− variants are ubiquitously expressed,
although at very low levels compared to the α+ variants. The existence of MEF2C α− variants gave us the
opportunity to study for the first time the function of exon α. Transactivation experiments show that the
presence of exon α induces a reduction of transcription levels.Moreover, α−variants are significantly expressed
during neuronal cell differentiation, indicating a putative role of these variants in development
Metabolism and TAM functions: it takes two to tango
Full text linkFrom the evidence on clinical studies and experimental mouse models we now know that tumor associated macrophages (TAMs) sustain tumor development in many different ways. They play a role in angiogenesis, tumor cell invasion and metastasis formation. Additionally, TAMs interfere with natural killer and T cell antitumoral activities, producing an immune suppressive environment that protects tumor cell growth. This indicates that the tumoricidal activity of macrophages within the tumor microenviroment is lost due to an imbalance of the regulatory mechanisms underpinning these cells' function. Since metabolism is emerging as a major modulator of macrophage function, metabolic changes in response to signals coming from cancer or other immune cells might promote this imbalance, enhancing the tumorigenic activities of TAMs. In this review we describe the novel, most recent findings on how metabolism shapes TAM functions or conversely, how TAMs influence the activity of other cells through metabolic mechanisms. The complete elucidation of the metabolic switches between pro- and anti-tumoral properties of macrophages, now still in its infancy, is destined to provide scientists with new instruments not only to understand but also to combat cancer
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Pharmacological targets of metabolism in disease: Opportunities from macrophages
Full text linkFrom advances in the knowledge of the immune system, it is emerging that the specialized functions displayed by macrophages during the course of an immune response are supported by specific and dynamically-connected metabolic programs. The study of immunometabolism is demonstrating that metabolic adaptations play a critical role in modulating inflammation and, conversely, inflammation deeply influences the acquisition of specific metabolic settings. This strict connection has been proven to be crucial for the execution of defined immune functional programs and it is now under investigation with respect to several human disorders, such as diabetes, sepsis, cancer, and autoimmunity. The abnormal remodelling of the metabolic pathways in macrophages is now emerging as both marker of disease and potential target of therapeutic intervention. By focusing on key pathological conditions, namely obesity and diabetes, rheumatoid arthritis, atherosclerosis and cancer, we will review the metabolic targets suitable for therapeutic intervention in macrophages. In addition, we will discuss the major obstacles and challenges related to the development of therapeutic strategies for a pharmacological targeting of macrophage's metabolism
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