Metabolic reprogramming of arachidonic acid in clear cell renal carcinoma promotes an immunosuppressive microenvironment by activating MDK signaling pathway.

Metabolic reprogramming is a key feature of clear cell renal cell carcinoma (ccRCC), and metabolic abnormality can lead to significant changes in gene expression, resulting in the immunosuppressive microenvironment. In this study, we used a combination of single-cell RNA sequencing and bulk RNA sequencing to investigate the relationships between ccRCC metabolic reprogramming and immune exhaustion. Metabolic subtypes of ccRCC patients were constructed using bulk RNA sequencing. Tumor cells of different metabolic subtypes were analyzed and extracted by the Scissor algorithm, using single-cell RNA sequencing. The molecular mechanisms of abnormal metabolic regulating tumor immunity were explored using cell-cell communication analysis. In addition, the correlations between relevant molecules and immune exhaustion signals were verified in ccRCC by immunohistochemistry. The molecular mechanisms of metabolic abnormalities leading to immune exhaustion were validated via Western blotting, ELISA, cell co-culture and immunotherapy models. ccRCC patients can be divided into MT1 and MT2 metabolic subtypes. The MT2 subtype has a poorer prognosis and lower response to immunotherapy. Abnormal metabolism of arachidonic acid is a prominent feature of the MT2 subtype, and activates the MDK signaling pathway. As a secreted protein, MDK can further recruit immunosuppressive cells, such as Treg, Tex, and TAM. Blocking the arachidonic acid COX metabolic pathway significantly reduces the expression and secretion levels of MDK, thereby reprogramming the tumor microenvironment to promote anti-tumor immunity. Abnormal metabolism of arachidonic acid plays an important role in promoting immune exhaustion by activating the MDK signaling pathway. MDK may serve as an important biomarker for predicting the immune therapy response in ccRCC. By reducing MDK secretion, targeting blockade of arachidonic acid metabolism may be an effective treatment strategy to enhance the efficacy of immunotherapy in ccRCC.