Cholesterol suppresses AMFR-mediated PDL1 ubiquitination and degradation in HCC.

The degradation of proteasomes or lysosomes is emerging as a principal determinant of programmed death ligand 1 (PDL1) expression, which affects the efficacy of immunotherapy in various malignancies. Intracellular cholesterol plays a central role in maintaining the expression of membrane receptors; however, the specific effect of cholesterol on PDL1 expression in cancer cells remains poorly understood. Cholesterol starvation and stimulation were used to modulate the cellular cholesterol levels. Immunohistochemistry and western blotting were used to analyze the protein levels in the samples and cells. Quantitative real-time PCR, co-immunoprecipitation, and confocal co-localization assays were used for mechanistic investigation. A xenograft tumor model was constructed to verify these results in vivo. Our results showed that cholesterol suppressed the ubiquitination and degradation of PDL1 in hepatocellular carcinoma (HCC) cells. Further mechanistic studies revealed that the autocrine motility factor receptor (AMFR) is an E3 ligase that mediated the ubiquitination and degradation of PDL1, which was regulated by the cholesterol/p38 mitogenic activated protein kinase axis. Moreover, lowering cholesterol levels using statins improved the efficacy of programmed death 1 (PD1) inhibition in vivo. Our findings indicate that cholesterol serves as a signal to inhibit AMFR-mediated ubiquitination and degradation of PDL1 and suggest that lowering cholesterol by statins may be a promising combination strategy to improve the efficiency of PD1 inhibition in HCC.

S100 calcium-binding protein A9 from tumor-associated macrophage enhances cancer stem cell-like properties of hepatocellular carcinoma.

Tumor-associated macrophages (TAMs) are crucial components of the tumor microenvironment. They play vital roles in hepatocellular carcinoma (HCC) progression. However, the interactions between TAMs and HCC cells have not been fully characterized. In this study, TAMs were induced using human monocytic cell line THP-1 cells in vitro to investigate their functions in HCC progression. S100 calcium-binding protein A9 (S100A9), an inflammatory microenvironment-related secreted protein, was identified to be significantly upregulated in TAMs. S100A9 expression in tumor tissues was associated with poor survival of HCC patients. It could enhance the stem cell-like properties of HepG2 and MHCC-97H cells by activating nuclear factor-kappa B signaling pathway through advanced glycosylation end product-specific receptor in a Ca2+ -dependent manner. Furthermore, we found that, after treatment with S100A9, HepG2 and MHCC-97H cells recruited more macrophages via chemokine (CC motif) ligand 2, which suggests a positive feedback between TAMs and HCC cells. Taken together, our findings reveal that TAMs could upregulate secreted protein S100A9 and enhance the stem cell-like properties of HCC cells and provide a potential therapeutic target for combating HCC.

Spleen to non-cancerous liver volume ratio predicts liver cirrhosis in hepatocellular carcinoma patients.

PURPOSE: To investigate the performance of spleen to non-cancerous liver volume ratio (STnLR) for diagnosing liver cirrhosis in patients with hepatocellular carcinoma (HCC) during preoperative evaluation. METHODS: Patients were randomly divided into experiment group and validation group. Patients were grouped into cirrhosis group and non-cirrhosis group according to Scheuer staging. Patients' routine image data were reconstructed using a three-dimensional system. STnLR, spleen to liver volume ratio (STLR), spleen volume, aspartate aminotransferase to platelet ratio index (APRI), and fibrosis index based on the four factors (FIB-4) were calculated. Correlations between indices and cirrhosis were measured by Spearman correlation analysis. Diagnostic performance was assessed and compared using receiver operating characteristic analysis. Accuracies of the models were analyzed in validation group. RESULTS: No statistical difference in demographic and clinical characteristics was observed between groups. In experiment group, STnLR had the strongest correlation (r = 0.5399, P < 0.0001), and STLR, spleen volume, APRI, and FIB-4 had moderate correlations (r = 0.4583, 0.4123, 0.3648, and 0.3405, P < 0.0001, < 0.0001, < 0.0001, and = 0.0002) with liver cirrhosis stage. AUROC of STnLR (0.8326) was not statistically higher than that for spleen volume (0.7542, P = 0.09832) and STLR (0.8046, P = 0.3034), but was significantly higher than that for APRI (0.7099, P = 0.02046) and FIB-4 (0.7294, P = 0.03987). In validation group, STnLR showed the highest AUROC value (0.8538) and highest Youden index (0.5869) among all models. CONCLUSION: STnLR is an accurate and stable volumetric model to diagnose hepatic cirrhosis in the HCC population, which is superior to APRI and FIB-4.

Cholesterol suppresses GOLM1-dependent selective autophagy of RTKs in hepatocellular carcinoma.

Aberrant activation of receptor tyrosine kinases (RTKs) and the subsequent metabolic reprogramming play critical roles in cancer progression. Our previous study has shown that Golgi membrane protein 1 (GOLM1) promotes hepatocellular carcinoma (HCC) metastasis by enhancing the recycling of RTKs. However, how this RTK recycling process is regulated and coupled with RTK degradation remains poorly defined. Here, we demonstrate that cholesterol suppresses the autophagic degradation of RTKs in a GOLM1-dependent manner. Further mechanistic studies reveal that GOLM1 mediates the selective autophagy of RTKs by interacting with LC3 through an LC3-interacting region (LIR), which is regulated by a cholesterol-mTORC1 axis. Lowering cholesterol by statins improves the efficacy of multiple tyrosine kinase inhibitors (TKIs) in vivo. Our findings indicate that cholesterol serves as a signal to switch GOLM1-RTK degradation to GOLM1-RTK recycling and suggest that lowering cholesterol by statin may be a promising combination strategy to improve the TKI efficiency in HCC.

ACOT12-Dependent Alteration of Acetyl-CoA Drives Hepatocellular Carcinoma Metastasis by Epigenetic Induction of Epithelial-Mesenchymal Transition.

Metabolic reprogramming plays an important role in supporting tumor growth. However, little is known about the metabolic alterations that promote cancer metastasis. In this study, we identify acyl-CoA thioesterase 12 (ACOT12) as a key player in hepatocellular carcinoma (HCC) metastasis. The expression of ACOT12 is significantly down-regulated in HCC tissues and is closely associated with HCC metastasis and poor survival of HCC patients. Gain- and loss-of-function studies demonstrate that ACOT12 suppresses HCC metastasis both in vitro and in vivo. Further mechanistic studies reveal that ACOT12 regulates the cellular acetyl-CoA levels and histone acetylation in HCC cells and that down-regulation of ACOT12 promotes HCC metastasis by epigenetically inducing TWIST2 expression and the promotion of epithelial-mesenchymal transition. Taken together, our findings link the alteration of acetyl-CoA with HCC metastasis and imply that ACOT12 could be a prognostic marker and a potential therapeutic target for combating HCC metastasis.

Osteopontin deficiency protects mice from cholesterol gallstone formation by reducing expression of intestinal NPC1L1.

Homeostasis of cholesterol is regulated by absorption in the intestine and synthesis in the liver. The authors previously demonstrated that OPN (osteopontin) exhibits the ability to alter hepatic cholesterol metabolism, thus affecting cholesterol gallstone formation in mice. The present study investigated the role of OPN in cholesterol gallstone formation, focusing on its effect on intestinal absorption of cholesterol. OPN gene knockout (OPN­/­) mice and wild­type mice were respectively fed with a chow or lithogenic diet (LD) for 8 weeks. Following an 8­week LD period, the incidence of gallstone, bile composition, level of serum and fecal lipids and the expression of intestinal associated genes were analyzed. OPN­/­ mice were protected from gallstone formation induced by 8 weeks' LD­feeding. This protective effect from OPN deficiency was associated with alterations in bile composition, including a reduced concentration of biliary cholesterol. Additionally, plasma cholesterol level was decreased in LD­fed OPN­/­ mice. The alterations primarily resulted from the decreased expression of intestinal Niemann­Pick C1­like (NPC1 L) 1, which is important in the intestinal absorption of cholesterol. The present study demonstrated that OPN deficiency reduced intestinal absorption of cholesterol by suppressing the expression of NPC1L1, thus protecting mice from cholesterol gallstone formation.

Osteopontin Deficiency Alters Biliary Homeostasis and Protects against Gallstone Formation.

The precipitation of excess biliary cholesterol as solid crystals is a prerequisite for cholesterol gallstone formation, which occurs due to disturbed biliary homeostasis. Biliary homeostasis is regulated by an elaborate network of genes in hepatocytes. If unmanaged, the cholesterol crystals will aggregate, fuse and form gallstones. We have previously observed that the levels of osteopontin (OPN) in bile and gallbladder were reduced in gallstone patients. However, the role and mechanism for hepatic OPN in cholesterol gallstone formation is undetermined. In this study, we found that the expression of hepatic OPN was increased in gallstone patients compared with gallstone-free counterparts. Then, we observed that OPN-deficient mice were less vulnerable to cholesterol gallstone formation than wild type mice. Further mechanistic studies revealed that this protective effect was associated with alterations of bile composition and was caused by the increased hepatic CYP7A1 expression and the reduced expression of hepatic SHP, ATP8B1, SR-B1 and SREBP-2. Finally, the correlations between the expression of hepatic OPN and the expression of these hepatic genes were validated in gallstone patients. Taken together, our findings reveal that hepatic OPN contributes to cholesterol gallstone formation by regulating biliary metabolism and might be developed as a therapeutic target for gallstone treatments.