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Experimental Metastasis and CTL Adoptive Transfer Immunotherapy Mouse Model
Published on: November 26, 2010
Immune suppression in MTAP-deficient cancers via glutamate metabolism and CXCL10 downregulation
Wen-Hsin Chang1,2,3,4, Jun Zhang2,3, Qi-Sheng Hong1,2
1Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, University of California, Davis, Davis, CA, United States.
Background:
Immune checkpoint inhibitors (ICIs) have transformed cancer therapy; however, their efficacy remains limited in certain tumor subtypes, including those deficient in methylthioadenosine phosphorylase (MTAP). MTAP-deficient cancers are characterized by immunosuppressive tumor microenvironments (TMEs) and poor T cell infiltration, as suggested by large-scale transcriptomic analyses. Yet, the underlying mechanisms and therapeutic vulnerabilities remain poorly defined.
Methods:
We employed murine tumor models and transcriptomic profiling to investigate the immunosuppressive features of MTAP-deficient tumors. To identify actionable vulnerabilities, we conducted a high-throughput screen using the LOPAC1280 compound library. Functional assays were performed to evaluate the effects of candidate compounds on tumor growth and immune signaling.
Results:
MTAP-deficient tumors exhibited significantly reduced CD45+ immune cell infiltration and resistance to ICI therapy. Transcriptomic analyses revealed that MTAP-deficient cancer cells reprogram immune signaling pathways and suppress the expression of CXCL10, a key chemokine for T cell recruitment, thereby contributing to a non-inflamed, "cold" TME. High-throughput screening revealed an increased dependence on glutamate metabolism in MTAP-deficient cells. Several glutamate pathway inhibitors, including the clinically tested glutaminase inhibitor CB-839, selectively impaired their growth. Remarkably, CB-839 also restored CXCL10 expression, particularly under immune co-culture conditions, indicating a dual effect of direct cytotoxicity and immune activation.
Conclusion:
These findings uncover a novel link between glutamate metabolism and immune modulation in MTAP-deficient tumors. Our study provides mechanistic and preclinical support for targeting glutamate pathways to both suppress tumor growth and convert immune-cold tumors into more immunoresponsive states, offering a promising strategy to enhance ICI efficacy in this challenging cancer subtype.
Insights
Targeting glutamate metabolism in MTAP-deficient cancers can overcome resistance to immune checkpoint inhibitors (ICIs). This approach not only suppresses tumor growth but also enhances immune cell infiltration, turning "cold" tumors into responsive ones.
Area of Science:
- Oncology
- Immunology
- Cancer Metabolism
Background:
- Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment but show limited efficacy in certain tumors, such as those lacking methylthioadenosine phosphorylase (MTAP).
- MTAP-deficient cancers often feature immunosuppressive tumor microenvironments (TMEs) and reduced T cell infiltration, hindering therapeutic responses.
- The precise mechanisms driving these immunosuppressive characteristics and potential vulnerabilities in MTAP-deficient tumors are not well understood.
Purpose of the Study:
- To investigate the immunosuppressive mechanisms in MTAP-deficient tumors and identify therapeutic vulnerabilities.
- To explore the potential of targeting metabolic pathways to enhance anti-tumor immunity and ICI efficacy.
Main Methods:
- Utilized murine tumor models and transcriptomic profiling to analyze MTAP-deficient tumors.
- Conducted high-throughput screening of a compound library to identify actionable vulnerabilities.
- Performed functional assays to assess the impact of candidate compounds on tumor growth and immune signaling.
Main Results:
- MTAP-deficient tumors showed decreased immune cell infiltration and resistance to ICI therapy.
- Transcriptomic analysis revealed suppressed CXCL10 expression, contributing to a "cold" TME.
- MTAP-deficient cells demonstrated an increased reliance on glutamate metabolism, with inhibitors like CB-839 selectively impairing growth and restoring CXCL10 expression.
Conclusions:
- Established a link between glutamate metabolism and immune modulation in MTAP-deficient tumors.
- Targeting glutamate pathways offers a dual strategy to inhibit tumor growth and enhance immune response.
- Provides preclinical evidence for using glutamate pathway inhibitors to improve ICI efficacy in MTAP-deficient cancers.
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