ArchiveSenescent macrophages have emerged as dynamic cells within the tumor microenvironment that significantly promote tumor progression through complex cellular and molecular functional alterations. This review explores the multifaceted roles of macrophage senescence in cancer, and establishes links between senescent macrophages and tumor progression from multiple perspectives, on the basis of the first comprehensive analysis of the molecular mechanisms and pathways involved. By systematically examining the diverse changes in senescent macrophages, this review integrates and analyzes their effects on tumors, thus offering a comprehensive and novel theoretical foundation, and practical insights for cancer treatment. Notably, by integrating current molecular research and therapeutic advancements, we summarize novel therapeutic strategies targeting senescent macrophages, including senolytics, senescence modulators, and cutting-edge immunotherapies, thereby highlighting the potential of senescent macrophages as a therapeutic target and introducing new opportunities for cancer treatment.
CD8+ T cell exhaustion, a critical challenge in the immune response to cancer, is characterized by a profound decline in the functionality of effector CD8+ T cells. This state of exhaustion is accompanied by the upregulation of various inhibitory receptors and significant shifts in both transcriptional and epigenetic profiles, thus ultimately leading to inadequate tumor control. Therapeutic strategies aimed at reversing CD8+ T cell exhaustion have the potential to rejuvenate immune responses and enhance treatment efficacy. This review compiles current knowledge regarding the molecular mechanisms underlying CD8+ T cell exhaustion, including the roles of immune checkpoint molecules, the tumor microenvironment, metabolic reprogramming, transcription factors, and epigenetic modifications. Emerging therapeutic approaches designed to combat CD8+ T cell exhaustion are evaluated, with emphasis on the modulation of immune checkpoints; targeting of metabolic and transcriptional changes; and exploration of other innovative strategies, such as epigenetic editing and engineered CAR-T cells. Importantly, we expand the exhaustion concept to immune cells beyond CD8+ T cells, such as CD4+ T cells, natural killer cells, and myeloid populations, thereby highlighting the broader implications of systemic immunosuppression in the cancer context. Finally, we propose avenues for future research aimed at further elucidating the factors and molecular mechanisms associated with CD8+ T cell exhaustion, thereby underscoring the critical need for strategies aimed at reversing this state to improve outcomes in cancer immunotherapy.
Tumor-associated macrophages (TAMs) exhibit heterogeneous properties including anti-tumorigenic and pro-tumorigenic phenotypes. The rate-limiting enzyme in de novo serine biosynthesis, 3-phosphoglycerate dehydrogenase (PHGDH), has a well-established role in cellular metabolism, yet its specific role in macrophages remains unknown.
Metabolomics assays were conducted to assess metabolite composition and dynamics in macrophages. Changes in polarization and immunosuppressive markers were validated with qRT-PCR. Bioinformatics was used to analyze immune cell subsets and associated metabolic pathways. Finally, ChIP-qPCR and co-immunoprecipitation assays were performed to elucidate the downstream regulatory mechanisms of PHGDH.
Serine metabolism was found to be downregulated in TAMs in breast cancer. Functional studies revealed that PHGDH inhibition promotes an M2-like phenotype and immunosuppressive functions in macrophages. Furthermore, PHGDH was found to undergo nuclear translocation during macrophage polarization. Mechanistically, nuclear PHGDH was found to regulate GLUD1 and GLS2 transcription via interaction with the transcription factor STAT3. Rescue experiments demonstrated that glutamine supplementation and STAT3 inhibition reversed the effects of PHGDH on macrophage function.
Our findings reveal a previously unrecognized non-canonical metabolic function of PHGDH, thus providing potential therapeutic targets in the tumor microenvironment for reversing malignant progression.
Based on multistage metabolomic profiling and Mendelian randomization analyses, the current study identified plasma metabolites that predicted the risk of developing gastric cancer (GC) and determined whether key metabolite levels modified the GC primary prevention effects.
Plasma metabolites associated with GC risk were identified through a case-control study. Bi-directional two-sample Mendelian randomization analyses were performed to determine potential causal relationships utilizing the Shandong Intervention Trial (SIT), a nested case-control study of the Mass Intervention Trial in Linqu, Shandong province (MITS), China, the UK Biobank, and the FinnGen project.
A higher genetic risk score for plasma L-aspartic acid was significantly associated with an increased GC risk in the northern Chinese population (SIT: HR = 1.26 per 1 SD change, 95% CI: 1.07–1.49; MITS: HR = 1.07, 95% CI: 1.00–1.14) and an increased gastric adenocarcinoma risk in FinnGen (OR = 1.68, 95% CI: 1.16–2.45). Genetically predicted plasma L-aspartic acid levels also modified the GC primary prevention effects with the beneficial effect of Helicobacter pylori eradication notably observed among individuals within the top quartile of L-aspartic acid level (P-interaction = 0.098) and the beneficial effect of garlic supplementation only for those within the lowest quartile of L-aspartic acid level (P-interaction = 0.02).
Elevated plasma L-aspartic acid levels significantly increased the risk of developing GC and modified the effects of GC primary prevention. Further studies from other populations are warranted to validate the modification effect of plasma L-aspartic acid levels on GC prevention and to elucidate the underlying mechanisms.
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