Aberrant cholesterol metabolic signaling impairs antitumor immunosurveillance through natural killer T cell dysfunction in obese liver

摘要

Obesity is a major risk factor for cancers including hepatocellular carcinoma(HCC)that develops from a background of non-alcoholic fatty liver disease(NAFLD).Hypercholesterolemia is a common comorbidity of obesity.Although cholesterol biosynthesis mainly occurs in the liver,its role in HCC development of obese people remains obscure.Using high-fat high-carbohydrate diet-associated orthotopic and spontaneous NAFLD-HCC mouse models,we found that hepatic cholesterol accumulation in obesity selectively suppressed natural killer T(NKT)cell-mediated antitumor immunosurveillance.Transcriptome analysis of human liver revealed aberrant cholesterol metabolism and NKT cell dysfunction in NAFLD patients.Notably,cholesterol-lowering rosuvastatin restored NKT expansion and cytotoxicity to prevent obesogenic diet-promoted HCC development.Moreover,suppression of hepatic cholesterol biosynthesis by a mammalian target of rapamycin(mTOR)inhibitor vistusertib preceded tumor regression,which was abolished by NKT inactivation but not CD8^(+)T cell depletion.Mechanistically,sterol regulatory element-binding protein 2(SREBP2)-driven excessive cholesterol production from hepatocytes induced lipid peroxide accumulation and deficient cytotoxicity in NKT cells,which were supported by findings in people with obesity,NAFLD and NAFLD-HCC.This study highlights mTORC1/SREBP2/cholesterol-mediated NKT dysfunction in the tumor-promoting NAFLD liver microenvironment,providing intervention strategies that invigorating NKT cells to control HCC in the obesity epidemic.