Tumorous cholesterol biosynthesis curtails anti-tumor immunity by preventing MTOR-TFEB-mediated lysosomal degradation of CD274/PD-L1

Enhanced cholesterol biosynthesis is a hallmark metabolic characteristic of cancer, exerting an oncogenic role by supplying intermediate metabolites that regulate intracellular signaling pathways. The pharmacological blockade of cholesterol biosynthesis has been well documented as a promising therapeutic approach in cancer. Particularly, cholesterol biosynthesis is linked to macroautophagy/autophagy and lysosome metabolism, with the engagement of the critical autophagy regulators like MTOR to be fully activated by lysosomal cholesterol trafficking and accumulation. Previous studies have primarily focused on the role of cholesterol biosynthesis in tumor cell-intrinsic biological processes, whereas its involvement in tumor immune evasion and the underlying mechanisms related to autophagy or lysosome metabolism remain elusive. Herein, through bioinformatics analysis we discovered a negative correlation between cholesterol biosynthesis and the score of tumor-infiltrating lymphocytes in cancers. Inhibition of tumor cell cholesterol biosynthesis leads to increased infiltration and activation of CD8⁺ T cells in the tumor microenvironment, which is largely responsible for the impairment of tumor growth. Mechanistically, cholesterol biosynthesis inhibition impairs the activation of MTOR at lysosomes, thereby promoting the nuclear translocation of TFEB and downstream lysosome biosynthesis, facilitating the degradation of CD274/PD-L1 within lysosomes in tumor cells. Ultimately, the HMGCR-MTOR-LAMP1 axis that connects cholesterol, lysosome and tumor immunology, predicts poor response to immunotherapy and worse prognosis of patients with melanoma. These findings unveil an immunomodulatory role of tumorous cholesterol biosynthesis via the regulation of CD274 lysosomal degradation. Targeting cholesterol biosynthesis holds promise as a potential therapeutic strategy in cancer, particularly when combined with immune checkpoint blockade. <b>Abbreviations:</b> ATG5, autophagy related 5; CD274/PD-L1, CD274 molecule; CQ, chloroquine; CTLA4, cytotoxic T-lymphocyte associated protein 4; CHX, cycloheximide; EIF4EBP1, eukaryotic translation initiation factor 4E binding protein 1; GSVA, gene set variation analysis; GZMB, granzyme B; HMGCR, 3-hydroxy-3-methylglutaryl-CoA reductase; IFNG/IFN-γ, Interferon gamma; IHC, Immunohistochemistry; LAMP1, lysosomal associated membrane protein 1; MITF, melanocyte inducing transcription factor; MTOR, mechanistic target of rapamycin kinase; NK, natural killer; NSCLC, non-small cell lung cancer; PBMC, peripheral blood mononuclear cell; PDCD1/PD-1, programmed cell death 1; qRT-PCR, quantitative real-time polymerase chain reaction; SKCM, skin cutaneous melanoma; TCGA, The Cancer Genome Atlas; TFE3, transcription factor binding to IGHM enhancer 3; TFEB, transcription factor EB; TIL, tumor infiltrated lymphocyte; TME, tumor microenvironment; T_reg, regulatory T.