Project description:The tumor's metabolic landscape significantly influences anti-tumor immunity, but it remains unclear how metabolic pathways commonly active in the organ of tumor-origin influence immunosurveillance. This study focused on the liver and identified accumulation of primary conjugated and secondary bile acids (BAs) as metabolic features associated with hepatocellular carcinoma and liver cancer models. Inhibiting conjugated BA synthesis through BAAT-deletion in hepatocytes enhanced tumor-specific T cell responses, reduced growth, and sensitized tumors to immune checkpoint blockade. BAs regulated CD8+ T cells differently; primary BAs like TCDCA induced oxidative stress and secondary BAs like LCA impaired T cell function through ER stress, which was countered by UDCA. Indeed, dietary UDCA provision suppressed tumor progression. These findings demonstrate how manipulating organ-specific metabolites affects antitumor immunity and modifying BA synthesis or dietary intake could enhance immunotherapy in liver cancer.
Project description:The tumor's metabolic landscape significantly influences anti-tumor immunity, but it remains unclear how metabolic pathways commonly active in the organ of tumor-origin influence immunosurveillance. This study focused on the liver and identified accumulation of primary conjugated and secondary bile acids (BAs) as metabolic features associated with hepatocellular carcinoma and liver cancer models. Inhibiting conjugated BA synthesis through BAAT-deletion in hepatocytes enhanced tumor-specific T cell responses, reduced growth, and sensitized tumors to immune checkpoint blockade. BAs regulated CD8+ T cells differently; primary BAs like TCDCA induced oxidative stress and secondary BAs like LCA impaired T cell function through ER stress, which was countered by UDCA. Indeed, dietary UDCA provision suppressed tumor progression. These findings demonstrate how manipulating organ-specific metabolites affects antitumor immunity and modifying BA synthesis or dietary intake could enhance immunotherapy in liver cancer.
Project description:The tumor's metabolic landscape significantly influences anti-tumor immunity, but it remains unclear how metabolic pathways commonly active in the organ of tumor-origin influence immunosurveillance. This study focused on the liver and identified accumulation of primary conjugated and secondary bile acids (BAs) as metabolic features associated with hepatocellular carcinoma and liver cancer models. Inhibiting conjugated BA synthesis through BAAT-deletion in hepatocytes enhanced tumor-specific T cell responses, reduced growth, and sensitized tumors to immune checkpoint blockade. BAs regulated CD8+ T cells differently; primary BAs like TCDCA induced oxidative stress and secondary BAs like LCA impaired T cell function through ER stress, which was countered by UDCA. Indeed, dietary UDCA provision suppressed tumor progression. These findings demonstrate how manipulating organ-specific metabolites affects antitumor immunity and modifying BA synthesis or dietary intake could enhance immunotherapy in liver cancer.
Project description:Specific bile acids are potent signaling molecules that modulate metabolic pathways affecting lipid, glucose and bile acid homeostasis, and the microbiota. Bile acids are synthesized from cholesterol in the liver, and the key enzymes involved in bile acid synthesis (Cyp7a1, Cyp8b1) are regulated transcriptionally by the nuclear receptor FXR. We have identified an FXR-regulated pathway upstream of a transcriptional repressor that controls multiple bile acid metabolism genes. We identify MafG as an FXR target gene and show that hepatic MAFG overexpression represses genes of the bile acid synthetic pathway and modifies the biliary bile acid composition. In contrast, loss-of-function studies using MafG(+/-) mice causes de-repression of the same genes with concordant changes in biliary bile acid levels. Finally, we identify functional MafG response elements in bile acid metabolism genes using ChIP-seq analysis. Our studies identify a molecular mechanism for the complex feedback regulation of bile acid synthesis controlled by FXR.
Project description:The disruption of cholesterol homeostasis leads to an increase in cholesterol levels which results in the development of cardiovascular disease. Mitogen Inducible Gene 6 (Mig-6) is an immediate early response gene that can be induced by various mitogens, stresses, and hormones. To identify the metabolic role of Mig-6 in the liver, we conditionally ablated Mig-6 in the liver using the Albumin-Cre mouse model (Albcre/+Mig-6f/f; Mig-6d/d). Mig-6d/d mice exhibit hepatomegaly and fatty liver. Serum levels of total, LDL, and HDL cholesterol and hepatic lipid were significantly increased in the Mig-6d/d mice. The daily excretion of fecal bile acids was significantly decreased in the Mig-6d/d mice. DNA microarray analysis of mRNA isolated from the livers of these mice showed alterations in genes that regulate lipid metabolism, bile acid, and cholesterol synthesis, while the expression of genes that regulate biliary excretion of bile acid and triglyceride synthesis showed no difference in the Mig-6d/d mice compared to Mig-6f/f controls. These results indicate that Mig-6 plays an important role in cholesterol homeostasis and bile acid synthesis. Mice with liver specific conditional ablation of Mig-6 develop hepatomegaly and increased intrahepatic lipid and provide a novel model system to investigate the genetic and molecular events involved in the regulation of cholesterol homeostasis and bile acid synthesis. Defining the molecular mechanisms by which Mig-6 regulates cholesterol homeostasis will provide new insights into the development of more effective ways for the treatment and prevention of cardiovascular disease. Eight week old Mig-6f/f vs Mig-6d/d male mice after undergoing a 24 hour fast
Project description:The disruption of cholesterol homeostasis leads to an increase in cholesterol levels which results in the development of cardiovascular disease. Mitogen Inducible Gene 6 (Mig-6) is an immediate early response gene that can be induced by various mitogens, stresses, and hormones. To identify the metabolic role of Mig-6 in the liver, we conditionally ablated Mig-6 in the liver using the Albumin-Cre mouse model (Albcre/+Mig-6f/f; Mig-6d/d). Mig-6d/d mice exhibit hepatomegaly and fatty liver. Serum levels of total, LDL, and HDL cholesterol and hepatic lipid were significantly increased in the Mig-6d/d mice. The daily excretion of fecal bile acids was significantly decreased in the Mig-6d/d mice. DNA microarray analysis of mRNA isolated from the livers of these mice showed alterations in genes that regulate lipid metabolism, bile acid, and cholesterol synthesis, while the expression of genes that regulate biliary excretion of bile acid and triglyceride synthesis showed no difference in the Mig-6d/d mice compared to Mig-6f/f controls. These results indicate that Mig-6 plays an important role in cholesterol homeostasis and bile acid synthesis. Mice with liver specific conditional ablation of Mig-6 develop hepatomegaly and increased intrahepatic lipid and provide a novel model system to investigate the genetic and molecular events involved in the regulation of cholesterol homeostasis and bile acid synthesis. Defining the molecular mechanisms by which Mig-6 regulates cholesterol homeostasis will provide new insights into the development of more effective ways for the treatment and prevention of cardiovascular disease.