Glutamine metabolic competition drives immunosuppressive reprogramming of intratumour GPR109A+ myeloid cells to promote liver cancer progression

Harnessing amino acid pathways to influence myeloid cell function in tumor immunity

Amino acids are pivotal regulators of immune cell metabolism, signaling pathways, and gene expression. In myeloid cells, these processes underlie their functional plasticity, enabling shifts between pro-inflammatory, anti-inflammatory, pro-tumor, and anti-tumor activities. Within the tumor microenvironment, amino acid metabolism plays a crucial role in mediating the immunosuppressive functions of myeloid cells, contributing to tumor progression. This review delves into the mechanisms by which specific amino acids-glutamine, serine, arginine, and tryptophan-regulate myeloid cell function and polarization. Furthermore, we explore the therapeutic potential of targeting amino acid metabolism to enhance anti-tumor immunity, offering insights into novel strategies for cancer treatment.

Targeting glutamine metabolism crosstalk with tumor immune response

Glutamine, akin to glucose, is a fundamental nutrient for human physiology. Tumor progression is often accompanied by elevated glutamine consumption, resulting in a disrupted nutritional balance and metabolic reprogramming within the tumor microenvironment. Furthermore, immune cells, which depend on glutamine for metabolic support, may experience functional impairments and dysregulation. Although the role of glutamine in tumors has been extensively studied, the specific impact of glutamine competition on immune responses, as well as the precise cellular alterations within immune cells, remains incompletely understood. In this review, we summarize the consequences of glutamine deprivation induced by tumor-driven glutamine uptake on immune cells, assessing the underlying mechanisms from the perspective of various components of the immune microenvironment. Additionally, we discuss the potential synergistic effects of glutamine supplementation and immunotherapy, offering insights into future research directions. This review provides compelling evidence for the integration of glutamine metabolism and immunotherapy as a promising strategy in cancer therapy.

Tumor-induced metabolic immunosuppression: Mechanisms and therapeutic targets

Metabolic reprogramming in both immune and cancer cells plays a crucial role in the antitumor immune response. Recent studies indicate that cancer metabolism not only sustains carcinogenesis and survival via altered signaling but also modulates immune cell function. Metabolic crosstalk within the tumor microenvironment results in nutrient competition and acidosis, thereby hindering immune cell functionality. Interestingly, immune cells also undergo metabolic reprogramming that enables their proliferation, differentiation, and effector functions. This review highlights the regulation of antitumor immune responses through metabolic reprogramming in cancer and immune cells and explores therapeutic strategies that target these metabolic pathways in cancer immunotherapy, including using chimeric antigen receptor (CAR)-T cells. We discuss innovative combinations of immunotherapy, cellular therapies, and metabolic interventions that could optimize the efficacy of existing treatment protocols.

Single-cell profiling of SLC family transporters: uncovering the role of SLC7A1 in osteosarcoma

BACKGROUND

Osteosarcoma is the most common malignant bone tumor in children and adolescents, characterized by high disability and mortality rates. Over the past three decades, therapeutic outcomes have plateaued, underscoring the critical need for innovative therapeutic targets. Solute carrier (SLC) family transporters have been implicated in the malignant progression of a variety of tumors, however, their specific role in osteosarcoma remains poorly understood.

METHODS

The single-cell sequencing data from GSE152048 and GSE162454, along with RNA-seq from the TARGET and GSE21257 cohorts, were utilized for the analysis in this study. LASSO regression analysis was conducted to identify prognostic genes and construct an SLC-related prognostic signature. Survival analysis and ROC analysis evaluated the validity of the prognostic signature. The ESTIMATE and CIBERSORT Packages were utilized to assess the immune infiltration status. Pseudotime and CellChat analyses were performed to investigate the relationship between SLC7A1, malignant phenotypes, and the immune microenvironment. CCK8 assays, EdU staining, colony formation assays, Transwell assays, and co-culture systems were used to assess the effects of SLC7A1 on cell proliferation, metastasis, and macrophage polarization. Finally, virtual docking identified potential drugs targeting SLC7A1.

RESULTS

SLCs displayed distinct expression patterns across various cell types within the osteosarcoma microenvironment, with myeloid cells exhibiting a preference for amino acid uptake. A prognostic model comprising nine genes was constructed via LASSO regression, with SLC7A1 showing the highest hazard ratio. Multiple analytical algorithms indicated that SLCs were associated with immune cell infiltration and immune checkpoint gene expression. Single-cell analysis indicated that SLC7A1 was predominantly expressed in osteosarcoma cells and correlated with various malignant tumor characteristics. SLC7A1 also regulate interactions between tumor cells and macrophages, as well as modulate macrophage function through multiple pathways. In vitro assays and survival analysis demonstrated that inhibition of SLC7A1 suppressed the malignant phenotype of osteosarcoma cells, with SLC7A1 expression correlating with poor prognosis. Co-culture models confirmed the involvement of SLC7A1 in macrophage polarization. Finally, virtual screening and CETSA identified Cepharanthine as potential inhibitors of SLC7A1.

CONCLUSION

SLC-related prognostic signatures can be utilized for the prognostic evaluation of osteosarcoma. Pharmacological inhibition of SLC7A1 may be a feasible therapeutic approach for osteosarcoma.

Photothermal nanocomposite reactivate "immune-hot" for triple-negative breast cancer treatment via glutamine metabolism reprograming

Herein, a photothermal nanocomposite PAI@CB839 nanoparticles (NPs) was constructed to perform a heat-immune therapy for triple-negative breast cancer (TNBC). Firstly, a photothermal agent animated IR780 was modified on a mPEG-NH2 using 4,4'-dicarboxylazobenzene as a linker. The synthesized PAI exhibited superior photothermal efficiency of the IR780 even after assembling in water. As a functional carrier, PAI was used to load and deliver the glutaminase inhibitor CB839 to tumor tissue. In the hypoxic environment of tumor cells, the azo bond would break, triggering the release of cargo. Upon irradiation, the outstanding photothermal properties of IR780 resulted in tumor cell damage. This process could promote immunogenic cell death and program tumor to "immune-hot" condition. Concurrently, CB839 strengthened the antitumor immune response by remodulating the immunosuppressive TME through disturbing Glu abnormal metabolism, which further inhibited TNBC growth and metastasis. In conclusion, PAI@CB839 NPs exhibited great antitumor efficiency, which pave a new way for TNBC therapeutic regimen development.

Hepatocellular carcinoma cells induce γδ T cells through metabolic reprogramming into tumor-progressive subpopulation

Tumor immune microenvironment (TIME) is a tiny structure that contains multiple immune cell components around tumor cells, which plays an important role in tumorigenesis, and is also the potential core area of activated immunotherapy. How immune cells with tumor-killing capacity in TIME are hijacked by tumor cells during the progression of tumorigenesis and transformed into subpopulations that facilitate cancer advancement is a question that needs to be urgently addressed nowadays. γδ T cells (their T cell receptors are composed of γ and δ chains), a unique T cell subpopulation distinguished from conventional αβ T cells, are involved in a variety of immune response processes through direct tumor-killing effects and/or indirectly influencing the activity of other immune cells. However, the presence of γδ T cells in the tumor microenvironment (TME) has been reported to be associated with poor prognosis in some tumors, suggesting that certain γδ T cell subsets may also have pro-tumorigenic effects. Recent studies have revealed that metabolic pathways such as activation of glycolysis, increase of lipid metabolism, enhancement of mitochondrial biosynthesis, alterations of fatty acid metabolism reshape the local TME, and immune cells trigger metabolic adaptation through metabolic reprogramming to meet their own needs and play the role of anti-tumor or immunosuppression. Combining previous studies and our bioinformatics results, we hypothesize that γδT cells compete for resources with hepatocellular carcinoma (HCC) cells by means of fatty acid metabolic regulation in the TME, which results in the weakening or loss of their ability to recognize and kill HCC cells through genetic and epigenetic alterations, thus allowing γδT cells to be hijacked by HCC cells as a subpopulation that promotes HCC progression.