Laurent Ehrlich

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.

Novel β‐catenin/farnesoid X receptor interaction regulates hepatic bile acid metabolism during cholestasis

b -Catenin, a 781–amino acid, 85.5-kDa scaffold protein, serves a range of molecular functions including cell-to-cell adhesion to gene transcription. It is highly evolutionarily conserved and indispensable for embryonic development. bCatenin is a binding partner of adenomatous polyposis coli protein, responsible for degrading b-catenin to prevent its nuclear accumulation and gene transcriptional function (Fig. 1A). Adenomatous polyposis coli is mutated in 80% of colon cancers and is the hereditary mutated gene in familial adenomatous polyposis disorder. b-Catenin is also important for liver development and carcinogenesis. As a key binding partner of Ecadherin in adherens junctions, b-catenin links the cytoskeleton of adjacent epithelial cells. How b-catenin carries out both cytoplasmic and nuclear functions, and the consequences of its dysregulation, remain a subject of much debate. In this original article by Thompson and colleagues, the authors describe a finely tuned interplay between b-catenin and farnesoid X receptor (FXR) in response to cholestatic injury.

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.

The Role of Cholangiocyte Cell Death in the Development of Biliary Diseases

Cholangiocytes are the targets of several liver diseases termed cholangiopathies that result in cholestasis and the development of hepatic fibrosis and carcinogenesis. There are numerous studies investigating the role of cholangiocyte death during the progression of cholangiopathies to end-stage liver disease. This chapter reviews the pathophysiology of primary sclerosing cholangitis, primary biliary cholangitis, autosomal dominant polycystic kidney disease, and biliary atresia. We will also discuss current animal models used to study these cholangiopathies and review the mechanisms of cell death in these disease processes, including the roles of innate immune system, apoptosis, senescence, autophagy, and lipoapoptosis. A thorough understanding of cholangiocyte death during cholestatic liver disease is critical to develop targeted therapies against these disease processes.

Novel β-catenin/FXR Interaction Regulates Hepatic Bile Acid Metabolism During Cholestasis

b -Catenin, a 781–amino acid, 85.5-kDa scaffold protein, serves a range of molecular functions including cell-to-cell adhesion to gene transcription. It is highly evolutionarily conserved and indispensable for embryonic development. bCatenin is a binding partner of adenomatous polyposis coli protein, responsible for degrading b-catenin to prevent its nuclear accumulation and gene transcriptional function (Fig. 1A). Adenomatous polyposis coli is mutated in 80% of colon cancers and is the hereditary mutated gene in familial adenomatous polyposis disorder. b-Catenin is also important for liver development and carcinogenesis. As a key binding partner of Ecadherin in adherens junctions, b-catenin links the cytoskeleton of adjacent epithelial cells. How b-catenin carries out both cytoplasmic and nuclear functions, and the consequences of its dysregulation, remain a subject of much debate. In this original article by Thompson and colleagues, the authors describe a finely tuned interplay between b-catenin and farnesoid X receptor (FXR) in response to cholestatic injury.

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 menins diverse functions is not fully understood. We show that small-molecule inhibitors affecting menin function can shed light on menins broad role in pathophysiology and elucidate distinct menin-dependent processes. This review reveals menins 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.