Abstract
BackgroundPancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers. Despite the successful application of immune checkpoint blockade in a range of human cancers, immunotherapy in PDAC remains unsuccessful. PDAC is characterized by a desmoplastic, hypoxic and highly immunosuppressive tumor microenvironment (TME), where T-cell infiltration is often lacking (immune desert), or where T cells are located distant from the tumor islands (immune excluded). Converting the TME to an immune-inflamed state, allowing T-cell infiltration, could increase the success of immunotherapy in PDAC.MethodIn this study, we use the KPC3 subcutaneous PDAC mouse model to investigate the role of tumor-derived sialic acids in shaping the tumor immune landscape. A sialic acid deficient KPC3 line was generated by genetic knock-out of the CMAS (cytidine monophosphate N-acetylneuraminic acid synthetase) enzyme, a critical enzyme in the synthesis of sialic acid-containing glycans. The effect of sialic acid-deficiency on immunotherapy efficacy was assessed by treatment with anti-programmed cell death protein 1 (PD-1) and agonistic CD40.ResultThe absence of sialic acids in KPC3 tumors resulted in increased numbers of CD4+and CD8+T cells in the TME, and reduced frequencies of CD4+regulatory T cells (Tregs) within the T-cell population. Importantly, CD8+T cells were able to infiltrate the tumor islands in sialic acid-deficient tumors. These favorable alterations in the immune landscape sensitized sialic acid-deficient tumors to immunotherapy, which was ineffective in sialic acid-expressing KPC3 tumors. In addition, high expression of sialylation-related genes in human pancreatic cancer correlated with decreased CD8+T-cell infiltration, increased presence of Tregs, and poorer survival probability.ConclusionOur results demonstrate that tumor-derived sialic acids mediate T-cell exclusion within the PDAC TME, thereby impairing immunotherapy efficacy. Targeting sialic acids represents a potential strategy to enhance T-cell infiltration and improve immunotherapy outcomes in PDAC.
Subject
Cancer Research,Pharmacology,Oncology,Molecular Medicine,Immunology,Immunology and Allergy
Cited by
2 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献