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.

SREBP2 inhibitor betulin sensitizes hepatocellular carcinoma to lenvatinib by inhibiting the mTOR/IL-1ß pathway.

Lenvatinib has become the first-line therapy in advanced hepatocellular carcinoma (HCC), but its efficacy is still limited because of the inevitable development of resistance. It has been reported that cellular cholesterol levels are associated with tyrosine kinase inhibitor (TKI) efficacy. Here, we show that betulin, a sterol regulatory element-binding protein 2 (SREBP2) inhibitor, markedly enhances the anti-tumor effect of lenvatinib in HCC both in vitro and in vivo. Our results also show that the combination treatment of lenvatinib and betulin synergistically inhibits the proliferation and clonogenicity of HCC cells. The mRNA and protein expressions of IL-1ß are markedly decreased in HCC cells treated with betulin, while the sensitivity of HCC cells to lenvatinib is enhanced. Moreover, we find that the knockdown of IL-1ß also enhances the efficacy of lenvatinib, and recombinant IL-1ß protein rescues cell viability, which is reduced by lenvatinib in HCC cells. Further mechanistic studies indicate that betulin decreases the level of IL-1ß in HCC cells by inhibiting the mTOR signaling pathway. Finally, the growth of the tumors in xenograft mouse models subjected to combination treatment is significantly suppressed. In summary, our study reveals that the SREBP2 inhibitor betulin sensitizes hepatocellular carcinoma to lenvatinib by inhibiting the mTOR/IL-1ß pathway, which may be a promising therapeutic strategy for patients with HCC.

27-Hydroxycholesterol promotes metastasis by SULT2A1-dependent alteration in hepatocellular carcinoma.

Oxysterol metabolism plays an important role in the initiation and development of various tumors. However, little is known that the metabolic alternation can promote the metastasis of hepatocellular carcinoma (HCC). In this study, we identify the sulfotransferase family 2A member 1 (SULT2A1) to 27-hydroxycholesterol (27-OHC) metabolic axis as playing a critical role in HCC metastasis. The level of 27-OHC closely corresponded with HCC metastasis instead of proliferation in vitro and in vivo. Also, the expression of SULT2A1 is extremely downregulated in human HCC tissues and is correlated with poor prognosis and tumor metastasis. Gain- and loss-of-function studies reveal that SULT2A1 suppresses the metastasis of HCC by regulating the level of 27-OHC. Further mechanistic studies indicated that SULT2A1-dependent alternation of 27-OHC activates the nuclear factor-κB signaling pathway and promotes HCC metastasis by enhancing Twist1 expression and epithelial-mesenchymal transition. In conclusion, our findings indicate the relationship between the metabolism of 27-OHC and the metastasis of HCC. Moreover, SULT2A1 could act as a potential prognostic biomarker and a therapeutic target for preventing HCC metastasis.

Lenvatinib Targets FGF Receptor 4 to Enhance Antitumor Immune Response of Anti-Programmed Cell Death-1 in HCC.

BACKGROUND AND AIMS: Recently, clinical trials of lenvatinib plus pembrolizumab in HCC have displayed an impressive objective response rate. This study aimed to clarify the mechanism for optimal patient selection. APPROACH AND RESULTS: First, in patients with HCC, lenvatinib-treated recurrent tumors had lower programmed death ligand 1 (PD-L1) expression and regulatory T cell (Treg) infiltration compared with matched primary tumors. Consistently, in C57BL/6 wild-type mice receiving anti-programmed cell death 1 (PD-1) therapy, PD-L1 expression and Treg infiltration in s.c. tumors were reduced when adding lenvatinib to the scheme. Mechanistically, on the one hand, FGF receptor 4 (FGFR4) was the most pivotal target in PD-L1 down-regulation by lenvatinib in vitro. Furthermore, lenvatinib reinforced the proteasomal degradation of PD-L1 by blocking the FGFR4-glycogen synthase kinase 3ß axis and rescued the sensitivity of interferon-γ-pretreated HCC cells to T-cell killing by targeting FGFR4. On the other hand, the level of IL-2 increased after anti-PD-1 treatment, but IL-2-mediated Treg differentiation was blocked by lenvatinib through targeting FGFR4 to restrain signal transducer and activator of transcription 5 (STAT5) phosphorylation. By regulating the variations in the number of Tregs and the tumor FGFR4 level in C57BL/6-forkhead box protein P3 (Foxp3DTR ) mice, we found that high levels of FGFR4 and Treg infiltration sensitized tumors to the combination treatment. Finally, high levels of FGFR4 and Foxp3 conferred immune tolerance but better response to the combined therapy in patient cohorts. CONCLUSIONS: Lenvatinib reduced tumor PD-L1 level and Treg differentiation to improve anti-PD-1 efficacy by blocking FGFR4. Levels of FGFR4 expression and Treg infiltration in tumor could serve as biomarkers for screening patients with HCC using lenvatinib plus anti-PD-1 combination therapy.

m6A target microRNAs in serum for cancer detection.

Recent studies have revealed the significant dysregulation of m6A level in peripheral blood in several cancer types and its value in diagnosis. Nonetheless, a biomarker for accurate screening of multiple cancer types has not been established based on the perspective of m6A modification. In this study, we aimed to develop a serum diagnostic signature based on the m6A target miRNAs for the mass detection of cancer. A total of 14965 serum samples with 12 cancer types were included. Based on training cohort (n=7299), we developed the m6A-miRNAs signature using a support vector machine algorithm for cancer detection. The m6A-miRNAs signature showed high accuracy, and its area under the curve (AUC) in the training, internal validation and external validation cohort reached 0.979 (95%CI 0.976 - 0.982), 0.976 (95%CI 0.973 - 0.979) and 0.936 (95%CI 0.922 - 0.951), respectively. In the performance of distinguishing cancer types, the m6A-miRNAs signature showed superior sensitivity in each cancer type and presented a satisfactory AUC in identifying lung cancer, gastric cancer and hepatocellular carcinoma. Additionally, the diagnostic performance of m6A-miRNAs was not interfered by the gender, age and benign disease. In short, this study revealed the value of serum circulating m6A miRNAs in cancer detection and provided a new direction and strategy for the development of novel biomarkers with high accuracy, low cost and less invasiveness for mass cancer screening, such as RNA modification.

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.

Proscillaridin A inhibits hepatocellular carcinoma progression through inducing mitochondrial damage and autophagy.

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths globally. At present, drug options for systemic treatment of HCC are very limited. There is an urgent need to develop additional effective drugs for HCC treatment. In the present study, we found that proscillaridin A (ProA), a cardiac glycoside, exerted a strong anticancer effect on multiple HCC cell lines. ProA significantly inhibited the cell proliferation, migration, and invasion of HCC cells. ProA also had a marked inhibitory effect on the progression of HCC in the MHCC97H xenograft nude mouse model. ProA-mediated suppression of HCC was closely related to cell apoptosis. ProA-treated HCC cells displayed significant mitochondrial damage and elevated reactive oxygen species production, resulting in profound cell apoptosis. Meanwhile, ProA also played a role in autophagy induction in HCC cells. Defects in autophagy partially relieved ProA's anticancer effect in HCC cells. Our findings demonstrate that ProA can effectively inhibit HCC progression and may serve as a potential therapeutic agent for HCC treatment.

Inhibition of PCSK9 prevents and alleviates cholesterol gallstones through PPARα-mediated CYP7A1 activation.

BACKGROUND & AIMS: Dysregulated cholesterol metabolism is the major factor responsible for cholesterol gallstones (CGS). Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a critical role in cholesterol homeostasis and its inhibitors secure approval for treating various cholesterol metabolic disorders such as hypercholesterolemia and cardiovascular diseases, but its role in CGS remains unclear. Our study aims to clarify mechanisms by which PCSK9 promotes CGS formation and explore the application of the PCSK9 inhibitor, alirocumab, in preventing and treating CGS. APPROACH & RESULTS: The expressions of PCSK9 were notably increased in CGS patients' serum, bile, and liver tissues compared to those without gallstones. Moreover, among CGS patients, hepatic PCSK9 was positively correlated with hepatic cholesterol and negatively correlated with hepatic bile acids (BAs), suggesting PCSK9 was involved in disrupted hepatic cholesterol metabolism related to CGS. Mechanistically, in vitro experiments demonstrated that inhibition of PCSK9 enhanced nuclear expression of PPARα by diminishing its lysosomal degradation and subsequently activated CYP7A1 transcription. Finally, inhibition of PCSK9 prevented CGS formation and dissolved the existing stones in CGS mice by elevating the conversion of cholesterol into BAs through PPARα-mediated CYP7A1 activation. Additionally, serum PCSK9 level may function as a prognostic signature to evaluate the therapeutic efficacy of PCSK9 inhibitors. CONCLUSIONS: Inhibition of PCSK9 exerts preventive and therapeutic effects on CGS by activating PPARα-mediated CYP7A1 expression and facilitating the conversion of cholesterol into BAs, which highlights the potential of PCSK9 inhibition as a promising candidate for preventing and treating CGS in clinical applications. IMPACT AND IMPLICATIONS: PCSK9 plays a pivotal role in cholesterol metabolism and its inhibitors are approved for clinical use in cardiovascular diseases. Our study observes inhibition of PCSK9 prevents and dissolves CGS by activating PPARα-mediated CYP7A1 expression and facilitating the conversion of cholesterol into BAs. Mechanistically, PCSK9 inhibition enhanced the nuclear expression of PPARα by diminishing its lysosomal degradation and subsequently activated CYP7A1 transcription. Our study sheds light on the new function and mechanism of PCSK9 in CGS, providing a novel preventive and therapeutic target with potential clinical applications.

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.

Dual immune checkpoint inhibitors or combined with anti-VEGF agents in advanced, unresectable hepatocellular carcinoma.

BACKGROUND: Immune checkpoint inhibitor monotherapy did not show superiority of survival over standard therapy in advanced hepatocellular carcinoma. The combination immunotherapy including dual immune checkpoint inhibitors or combined with anti-VEGF agents have become a trend, but not fully evaluated. This study aimed to evaluate and compare distinct combination immunotherapy on efficacy in advanced hepatocellular carcinoma. METHODS: PubMed, Embase, Web of Science and Cochrane databases were systematically searched from inception to January 31, 2022. The primary endpoints were overall objective response rate (ORR), disease control rate (DCR), six-month progression-free survival rate (PFSR6m) and one-year overall survival rate (OSR1y). RESULTS: 11 studies with 16 independent cohorts and 3342 patients were included in the meta-analysis. Compared with first-line sorafenib, combination immunotherapy resulted in a significant improvement in ORR (RR, 2.74; 95%CI, 1.55-4.85; p = 0.0006), PFS (HR, 0.57; 95%CI, 0.49-0.65; p<0.0001) and OS (HR, 0.65; 95%CI, 0.52-0.82; p = 0.0002). Based on RECIST 1.1, the pooled ORR, PFSR6m and OSR1y for combination immunotherapy were 24.6% (95%CI: 20.3%-29.6%), 42.0% (95%CI: 34.2%-50.3%) and 61.8% (95%CI: 57.7%-65.7%), respectively. In distinct combination regimens, PD-1/L1 inhibitors plus anti-VEGF agents showed a significant superiority of clinical benefit than PD-1/L1 inhibitors plus CTLA-4 inhibitors (ORR: 25.2% vs 23.4%, p = 0.033; PFSR6m: 47.4% vs 23.2%, p<0.001; OSR1y: 65.1% vs 55.0%, p = 0.001). CONCLUSIONS: This study was the first meta-analysis to demonstrate the better survival benefit and tolerable toxicity of combination immunotherapy than standard therapy in advanced hepatocellular carcinoma. Compared with PD-1/L1 inhibitors plus CTLA-4 inhibitors, the regimens of PD-1/L1 inhibitors plus anti-VEGF agents may be associated with a significantly better clinical benefit. The difference in long-term survival and response population between two distinct combination regimens required further exploration.

ACOT12-mediated acetyl-CoA hydrolysis suppresses intrahepatic cholangiocarcinoma metastasis by inhibiting epithelial-mesenchymal transition.

Intrahepatic cholangiocarcinoma (ICC) is the most common malignant bile duct tumor in the liver and the second most common primary liver cancer with increasing morbidity and poor prognosis. Metabolic aberration plays key roles in cancer progression. As a key metabolic intermediate, acetyl-CoA accumulation shows close association with cancer metastasis. However, the role of acetyl-CoA metabolic aberration in ICC is still undetermined. Here, by investigating tissue samples from ICC patients and ICC cell lines, we found that acyl-CoA thioesterase 12 (ACOT12) expression is significantly down-regulated in ICC tissues, and is associated with poor prognosis of ICC. In vitro and in vivo studies demonstrated that ACOT12 suppressed ICC cells metastasis. Further mechanistic studies revealed that down-regulation of ACOT12 promoted ICC metastasis by inducing Slug expression and epithelial-mesenchymal transition (EMT). Our findings link ACOT12-regulated-acetyl-coA metabolic aberration with ICC metastasis and imply that ACOT12 could be a prognostic marker and a potential therapeutic target for ICC metastasis.

Rapamycin enhances the anti-tumor activity of cabozantinib in cMet inhibitor-resistant hepatocellular carcinoma.

Cabozantinib, mainly targeting cMet and vascular endothelial growth factor receptor 2, is the second-line treatment for patients with advanced hepatocellular carcinoma (HCC). However, the lower response rate and resistance limit its enduring clinical benefit. In this study, we found that cMet-low HCC cells showed primary resistance to cMet inhibitors, and the combination of cabozantinib and mammalian target of rapamycin (mTOR) inhibitor, rapamycin, exhibited a synergistic inhibitory effect on the in vitro cell proliferation and in vivo tumor growth of these cells. Mechanically, the combination of rapamycin with cabozantinib resulted in the remarkable inhibition of AKT, extracellular signal-regulated protein kinases, mTOR, and common downstream signal molecules of receptor tyrosine kinases; decreased cyclin D1 expression; and induced cell cycle arrest. Meanwhile, rapamycin enhanced the inhibitory effects of cabozantinib on the migration and tubule formation of human umbilical vascular endothelial cells and human growth factor-induced invasion of cMet inhibitor-resistant HCC cells under hypoxia condition. These effects were further validated in xenograft models. In conclusion, our findings uncover a potential combination therapy of cabozantinib and rapamycin to combat cabozantinib-resistant HCC.

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.

Epidemiology characteristics of ethnic minority colorectal cancer in Yunnan in Southwestern China.

BACKGROUND: Colorectal cancer (CRC) is one of the world's deadliest cancers, and its mortality rate has been on the rise in China. Yunnan is a region with a higher concentration of ethnic minorities. CRC affects many people from ethnic minority groups, which differ from Han in terms of their age and gender compositions. METHODS: We collected samples from 1,016 cases of CRC patients along with their case files at Yunnan Provincial Cancer Hospital from the period between January 2013 and December 2018. RESULTS: In total, 7.1% (n=72) of all lung cancer cases diagnosed from 2013 to 2018 in Yunnan Provincial Cancer Hospital occurred in patients 40 years old or younger, 44% (n=447) were 40 to 60 years old, and 48.9% (n=497) were 60 years old or above. The composition ratio of CRC patients in the different age groups differed significantly and enhanced significantly with age, with a statistical significance of P<0.05. A total of 33.6% (n=38) of 113 minority patients and 16.8% (n=152) of 903 Han patients reported a history of smoking, and 23.0% (n=26) of 113 minority patients and 14.6% (n=132) of Han patients had a history of drinking. Long-term smoking and drinking are significantly associated with the incidence of CRC, and this was more significant among ethnic minorities (P<0.05). CONCLUSIONS: The high incidence of CRC in Yunnan is strongly related to patients' lifestyles, and diet should be a core focus of efforts to prevent and treat CRC. Early screening and regular check for common tumor markers can also help to reduce the incidence of CRC and provide a basis for improvements in CRC treatment and prognosis in Yunnan.

Liver X Receptor Agonism Sensitizes a Subset of Hepatocellular Carcinoma to Sorafenib by Dual-Inhibiting MET and EGFR.

Sorafenib is the first approved systemic therapy for advanced hepatocellular carcinoma (HCC) and is the first-line choice in clinic. Sustained activation of receptor tyrosine kinases (RTKs) is associated with low efficacy of sorafenib in HCC. Activation of liver X receptor (LXR) has been reported to inhibit some RTKs. In this study, we found that the LXR agonist enhanced the anti-tumor activity of sorafenib in a subset of HCC cells with high LXR-ß/α gene expression ratio. Mechanically, the activation of LXR suppressed sorafenib dependent recruitment of MET and epidermal growth factor receptor (EGFR) in lipid rafts through cholesterol efflux. Our findings imply that LXR agonist can serve as a potential sensitizer to enhance the anti-tumor effect of sorafenib.

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.