miR-24 Inhibition Increases Menin Expression and Decreases Cholangiocarcinoma Proliferation.

Menin (MEN1) is a tumor-suppressor protein in neuroendocrine tissue. Therefore, we tested the novel hypothesis that menin regulates cholangiocarcinoma proliferation. Menin and miR-24 expression levels were measured in the following intrahepatic and extrahepatic cholangiocarcinoma (CCA) cell lines, Mz-ChA-1, TFK-1, SG231, CCLP, HuCCT-1, and HuH-28, as well as the nonmalignant human intrahepatic biliary line, H69. miR-24 miRNA and menin protein levels were manipulated in vitro in Mz-ChA-1 cell lines. Markers of proliferation and angiogenesis (Ki-67, vascular endothelial growth factors A/C, vascular endothelial growth factor receptors 2/3, angiopoietin 1/2, and angiopoietin receptors 1/2) were evaluated. Mz-ChA-1 cells were injected into the flanks of nude mice and treated with miR-24 inhibitor or inhibitor scramble. Menin expression was decreased in advanced CCA specimens, whereas miR-24 expression was increased in CCA. Menin overexpression decreased proliferation, angiogenesis, migration, and invasion. Inhibition of miR-24 increased menin protein expression while decreasing proliferation, angiogenesis, migration, and invasion. miR-24 was shown to negatively regulate menin expression by luciferase assay. Tumor burden and expression of proliferative and angiogenic markers was decreased in the miR-24 inhibited tumor group compared to controls. Interestingly, treated tumors were more fibrotic than the control group. miR-24-dependent expression of menin may be important in the regulation of nonmalignant and CCA proliferation and may be an additional therapeutic tool for managing CCA progression.

Nicotine Promotes Cholangiocarcinoma Growth in Xenograft Mice.

Nicotine, the main addictive substance in tobacco, is known to play a role in the development and/or progression of a number of malignant tumors. However, nicotine's involvement in the pathogenesis of cholangiocarcinoma is controversial. Therefore, we studied the effects of nicotine on the growth of cholangiocarcinoma cells in vitro and the progression of cholangiocarcinoma in a mouse xenograft model. The predominant subunit responsible for nicotine-mediated proliferation in normal and cancer cells, the α7 nicotinic acetylcholine receptor (α7-nAChR), was more highly expressed in human cholangiocarcinoma cell lines compared with normal human cholangiocytes. Nicotine also stimulated the proliferation of cholangiocarcinoma cell lines and promoted α7-nAChR-dependent activation of proliferation and phosphorylation of extracellular-regulated kinase in Mz-ChA-1 cells. In addition, nicotine and PNU282987 (α7-nAChR agonist) accelerated the growth of the cholangiocarcinoma tumors in our xenograft mouse model and increased fibrosis, proliferation of the tumor cells, and phosphorylation of extracellular-regulated kinase activation. Finally, α7-nAChR was expressed at significantly higher levels in human cholangiocarcinoma compared with normal human control liver samples. Taken together, results of this study suggest that nicotine acts through α7-nAChR and plays a novel role in the pathogenesis of cholangiocarcinoma. Furthermore, nicotine may act as a mitogen in cholestatic liver disease processes, thereby facilitating malignant transformation.

α7-nAChR Knockout Mice Decreases Biliary Hyperplasia and Liver Fibrosis in Cholestatic Bile Duct-Ligated Mice.

α7-nAChR is a nicotinic acetylcholine receptor [specifically expressed on hepatic stellate cells (HSCs), Kupffer cells, and cholangiocytes] that regulates inflammation and apoptosis in the liver. Thus, targeting α7-nAChR may be therapeutic in biliary diseases. Bile duct ligation (BDL) was performed on wild-type (WT) and α7-nAChR-/- mice. We first evaluated the expression of α7-nAChR by immunohistochemistry (IHC) in liver sections. IHC was also performed to assess intrahepatic bile duct mass (IBDM), and Sirius Red staining was performed to quantify the amount of collagen deposition. Immunofluorescence was performed to assess colocalization of α7-nAChR with bile ducts (costained with CK-19) and HSCs (costained with desmin). The mRNA expression of α7-nAChR, Ki-67/PCNA (proliferation), fibrosis genes (TGF-ß1, fibronectin-1, Col1α1, and α-SMA), and inflammatory markers (IL-6, IL-1ß, and TNF-α) was measured by real-time PCR. Biliary TGF-ß1 and hepatic CD68 (Kupffer cell marker) expression was assessed using IHC. α7-nAChR immunoreactivity was observed in both bile ducts and HSCs and increased following BDL. α7-nAChR-/- BDL mice exhibited decreased (i) bile duct mass, liver fibrosis, and inflammation, and (ii) immunoreactivity of TGF-ß1 as well as expression of fibrosis genes compared to WT BDL mice. α7-nAChR activation triggers biliary proliferation and liver fibrosis and may be a therapeutic target in managing extrahepatic biliary obstruction.

Inhibition of microRNA-24 increases liver fibrosis by enhanced menin expression in Mdr2-/- mice.

BACKGROUND: Liver transplantation remains the primary treatment for primary sclerosing cholangitis (PSC). Mdr2-/- mice provide a reliable in vivo model of PSC and develop characteristic biliary inflammation and fibrosis. We tested the hypothesis that the tumor suppressor protein menin is implicated in the progression of liver fibrosis and that menin expression can be regulated in the liver via microRNA-24 (miR-24). MATERIALS AND METHODS: Menin expression was measured in human PSC and Mdr2-/- mice. Twelve-week-old FVB/NJ wild-type (WT) and Mdr2-/- mice were treated with miR-24 Vivo-Morpholino to knockdown miR-24 expression levels. Liver fibrosis was evaluated by Sirius Red staining and quantitative polymerase chain reaction (qPCR) for genes associated with liver fibrosis, such as fibronectin 1, collagen type 1 alpha 1, transforming growth factor-ß1 (TGF-ß1), and α-smooth muscle actin. Studies were also performed in vitro using immortalized murine cholangiocyte lines treated with miR-24 hairpin inhibitor and mimic. RESULTS: Menin gene expression was increased in Mdr2-/- mice and late-stage human PSC samples. Treatment of FVB/NJ WT and Mdr2-/- mice with miR-24 Vivo-Morpholino increased menin expression, which correlated with increased expression of fibrosis genes. In vitro, inhibition of miR-24 also significantly increased the expression of fibrosis genes. CONCLUSIONS: Inhibition of miR-24 increases menin and TGF-ß1 expression, subsequently increasing hepatic fibrosis in FVB/NJ WT and Mdr2-/- mice. Modulation of the menin/miR-24 axis may provide novel targeted therapies to slow the progression of hepatic fibrosis into cirrhosis in PSC patients by altering TGF-ß1 expression.

A Review of the Scaffold Protein Menin and its Role in Hepatobiliary Pathology.

Multiple endocrine neoplasia type 1 (MEN1) is a familial cancer syndrome with neuroendocrine tumorigenesis of the parathyroid glands, pituitary gland, and pancreatic islet cells. The MEN1 gene codes for the canonical tumor suppressor protein, menin. Its protein structure has recently been crystallized, and it has been investigated in a multitude of other tissues. In this review, we summarize recent advancements in understanding the structure of the menin protein and its function as a scaffold protein in histone modification and epigenetic gene regulation. Furthermore, we explore its role in hepatobiliary autoimmune diseases, cancers, and metabolic diseases. In particular, we discuss how menin expression and function are regulated by extracellular signaling factors and nuclear receptor activation in various hepatic cell types. How the many signaling pathways and tissue types affect menin's diverse functions is not fully understood. We show that small-molecule inhibitors affecting menin function can shed light on menin's broad role in pathophysiology and elucidate distinct menin-dependent processes. This review reveals menin's often dichotomous function through analysis of its role in multiple disease processes and could potentially lead to novel small-molecule therapies in the treatment of cholangiocarcinoma or biliary autoimmune diseases.

miR-34a-dependent overexpression of Per1 decreases cholangiocarcinoma growth.

BACKGROUND & AIMS: Disruption of circadian rhythm is associated with cancer development and progression. MicroRNAs (miRNAs) are a class of small non-coding RNAs that trigger mRNA translation inhibition. We aimed to evaluate the role of Per1 and related miRNAs in cholangiocarcinoma growth. METHODS: The expression of clock genes was evaluated in human cholangiocarcinoma tissue arrays and cholangiocarcinoma lines. The rhythmic expression of clock genes was evaluated in cholangiocarcinoma cells and H69 (non-malignant cholangiocytes) by qPCR. We measured cell proliferation, cell cycle and apoptosis in Mz-ChA-1 cells after Per1 overexpression. We examined tumor growth in vivo after injection of Per1 overexpressing cells. We verified miRNAs that targets Per1. The circadian rhythm of miR-34a was evaluated in cholangiocarcinoma and H69 cells. We evaluated cell proliferation, apoptosis and invasion after inhibition of miR-34a in vitro, and the potential molecular mechanisms by mRNA profiling after overexpression of Per1. RESULTS: Expression of Per1 was decreased in cholangiocarcinoma. The circadian rhythm of Per1 expression was lost in cholangiocarcinoma cells. Decreased cell proliferation, lower G2/M arrest, and enhanced apoptosis were shown in Per1 overexpressing cells. An in vivo study revealed decreased tumor growth, decreased proliferation, angiogenesis and metastasis after overexpressing Per1. Per1 was verified as a target of miR-34a. miR-34a was rhythmically expressed in cholangiocarcinoma cells and H69. The inhibition of miR-34a decreased proliferation, migration and invasion in cholangiocarcinoma cells. mRNA profiling has shown that overexpression of Per1 inhibits cell growth through regulation of multiple cancer-related pathways, such as cell cycle, cell growth and apoptosis pathways. CONCLUSIONS: Disruption of circadian rhythms of clock genes contribute to the malignant phenotypes of human cholangiocarcinoma. LAY SUMMARY: The current study is about how biological clock and its regulators affect the bile duct tumor growth. The disruption of biological clock has a negative impact in different cancers. Per1 is a gene that is involved in maintaining the biological clock and show 24h oscillation. Reduced levels of Per1 and disruption of 24h circadian rhythm was found in bile duct cancer cells. Therefore, a genetic modified bile duct cancer cells was created. It has a higher level of Per1 expression and partially recovered circadian rhythm. Those genetic modified cells also displayed slower cell growth or higher rate of cell death. We also used mice model that lack of immune system to show that our genetic modified bile duct cells form smaller tumor. In addition, we tried to see how Per1 is communicating with other genes in regarding of controlling the tumor growth. We found Per1 is regulated by microRNA-34a, a small non-coding RNA that directly binds to genes and inhibit gene expression. Decreased level of miR-34a has also significantly reduced tumor growth through controlling the cell growth and cell death balance. Therefore bile duct cancer patients may be treated with miR-34a inhibitor or Per1 stimulator in the future.

Weakly hydrated surfaces and the binding interactions of small biological solutes.

Extended planar hydrophobic surfaces, such as are found in the side chains of the amino acids histidine, phenylalanine, tyrosine, and tryptophan, exhibit an affinity for the weakly hydrated faces of glucopyranose. In addition, molecular species such as these, including indole, caffeine, and imidazole, exhibit a weak tendency to pair together by hydrophobic stacking in aqueous solution. These interactions can be partially understood in terms of recent models for the hydration of extended hydrophobic faces and should provide insight into the architecture of sugar-binding sites in proteins.

Copy-number variation in congenital heart disease.

Genomic copy-number variants (CNVs) contribute to as many congenital heart disease (CHD) cases (10-15%) as chromosomal aberrations or single-gene mutations and influence clinical outcomes. CNVs in a few genomic hotspots (1q21.1, 2q13, 8p23.1, 11q24, 15q11.2, 16p11.2, and 22q11.2) are recurrently enriched in CHD cohorts and affect dosage-sensitive transcriptional regulators that are required for cardiac development. Reduced penetrance and pleiotropic effects on brain and heart development are common features of these CNVs. Therefore, additional genetic 'hits,' such as a second CNV or gene mutation, are probably required to cause CHD in most cases. Integrative analysis of CNVs, genome sequence, epigenetic alterations, and gene function will be required to delineate the complete genetic landscape of CHD.

Biliary epithelium: A neuroendocrine compartment in cholestatic liver disease.

Hepatic fibrosis is characterized by abnormal accumulation of extracellular matrix (ECM) that can lead to ductopenia, cirrhosis, and even malignant transformation. In this review, we examine cholestatic liver diseases characterized by extensive biliary fibrosis such as primary sclerosing cholangitis (PSC), primary biliary cholangitis (PBC), polycystic liver disease (PLD), and MDR2-/- and BDL mouse models. Following biliary injury, cholangiocytes, the epithelial cells that line the bile ducts, become reactive and adopt a neuroendocrine phenotype in which they secrete and respond to neurohormones and neuropeptides in an autocrine and paracrine fashion. Emerging evidence indicates that cholangiocytes influence and respond to changes in the ECM and stromal cells in the microenvironment. For example, activated myofibroblasts and hepatic stellate cells are major drivers of collagen deposition and biliary fibrosis. Additionally, the liver is richly innervated with adrenergic, cholinergic, and peptidergic fibers that release neurohormones and peptides to maintain homeostasis and can be deranged in disease states. This review summarizes how cholangiocytes interact with their surrounding environment, with particular focus on how autonomic and sensory regulation affects fibrotic pathophysiology.

Inhibition of the apelin/apelin receptor axis decreases cholangiocarcinoma growth.

PURPOSE: Cholangiocarcinoma (CCA) is a malignancy of the biliary epithelium that is associated with low five-year survival. The apelin receptor (APLNR), which is activated by the apelin peptide, has not been studied in CCA. The purpose of this study is to determine if inhibition of the apelin/APLNR axis can inhibit CCA growth. METHODS: Immunohistochemistry, rtPCR, immunofluorescence, flow cytometry, and ELISA was used to measure APLNR expression in human CCA cells and tissues. Mz-ChA-1 cells were treated with increasing concentrations of apelin and ML221, an APLNR antagonist. Expression of proliferative and angiogenic genes were measured via rtPCR. In vivo, Mz-ChA-1 cells were injected into the flanks of nu/nu mice, which were treated with ML221 (150 µg/kg) via tail vein injection. RESULTS: Expression of the apelin/APLNR axis was increased in CCA. In vitro, CCA proliferation and angiogenesis was inhibited by ML221 treatment. ML221 treatment significantly decreased tumor growth in nu/nu mice. CONCLUSION: The apelin/APLNR axis regulates CCA proliferation and angiogenesis. Inhibition of the apelin/APLNR axis decreases tumor growth in our xenograft model. Targeting APLNR signaling has the potential to serve as a novel, tumor directed therapy for CCA.