The cells transgressed to the lower side of the membrane were fixed in 4% paraformaldehyde, stained with 46-diamidino-2-phenylindole dichlorhydrate (DAPI; Merck Millipore, Darmstadt, Germany) and counted in four randomly selected visual fields per well (magnification, 200)

The cells transgressed to the lower side of the membrane were fixed in 4% paraformaldehyde, stained with 46-diamidino-2-phenylindole dichlorhydrate (DAPI; Merck Millipore, Darmstadt, Germany) and counted in four randomly selected visual fields per well (magnification, 200). and vimentin in HIBECs. Decreased mRNA levels of E-cadherin accompanied by higher mRNA levels of vimentin were observed in the 10, 20, 50, 100g/l IL-6 groups compared to those in the 0g/l group (all P <0. 05). Furthermore, the protein expression of E-cadherin was decreased, while that of vimentin was increased in the 50 and 100g/l IL-6 groups compared to those in the 0, 10 and 20g/l IL-6 groups (all P <0. 05). The present study therefore indicated that IL-6 promoted the process of EMT in HIBECs as characterized by increased migration and invasion of HIBECs and the typical changes in mRNA and protein expression of the EMT markers E-cadherin and vimentin. Keywords: epithelial-mesenchymal transition, interleukin-6, human intrahepatic biliary epithelial cell, morphological changes, migration == Introduction == Epithelial-mesenchymal transition (EMT), the programmed conversion of epithelial into mesenchymal cells, is defined by a loss of epithelial-cell characteristics, including cell-cell adhesion, polarity and organized cytoskeleton (1). The EMT may be involved in several physiological functions and pathological conditions, including normal development, fibrosis and tumor metastasis, through signaling pathways activated by various stimuli (24). A previous study on the EMT in biliary epithelial cells (BECs) in advanced liver fibrosis reported cytoskeletal rearrangements during chronic liver injury, resulting in a mesenchymal phenotype (5). BECs, also known as cholangiocytes, are essential to the formation of bile components in the liver and effective transport of bile into the duodenum, although they comprise only 35% of total cells in the normal liver (6, 7). BECs line the intra-hepatic biliary ducts, which are sites of damage in several diseases, including primary biliary cirrhosis and primary sclerosing cholangitis, and BECs may have active roles in the innate as well as the adaptive immune response by producing interleukin (IL)-6 and IL-8 following injury (810). IL-6 was identified as an important pleiotropic cytokine DP2.5 participating in acute inflammation, and previous molecular and pathological findings showed that intrahepatic BECs are able to synthesize IL-6, which is a critical mediator of the hepatic response to systemic inflammation (11, 12). It has been suggested that stimulation of human intrahepatic (HI) BECs with lipopolysaccharide resulted in increased secretion of IL-6 (8). In addition , previous studies suggested that IL-6 is a potent mitogen to BECs, and the growth of a cholangiocarcinoma cell line was attenuated by inhibition Lazabemide of IL-6-induced mitogen-mediated protein kinase activation, indicating a growth-regulatory function of IL-6 in HIBECs (13, 14). The EMT is associated with elevated E-cadherin and vimentin expression, as well as IL-6 production. Of Lazabemide note, IL-6 has been reported to be a potent inducer of the EMT in a number of tumor cell types (1518). The present study aimed to identify factors regulating EMT in HIBECs, while a possible IL-6-mediated EMT in HIBECs has not yet been reported, to the best of our knowledge. Therefore , the effects of IL-6 stimulation on the EMT of HIBECs Lazabemide were assessedin vitro, and the underlying mechanisms were investigated. == Materials and methods == == Cell Lazabemide culture == HIBEC lines (P5100) were purchased from ScienCell Research Laboratories (San Diego, CA, USA). All HIBEC lines were cultured in a humidified incubator at 37C and 5% CO2and maintained in a mixture of Dulbecco’s modified Eagle’s medium (DMEM)/Ham’s F12 (1: 1) medium Lazabemide (Gibco; Thermo Fisher Scientific, Inc., Waltham, MA, USA) supplemented with 5% fetal bovine serum (FBS), 5 ng/ml epidermal growth factor, 0. 4g/ml succinyl hydrocortisone, 2 nmol/l triiodothyronine, 5g/ml insulin and 10g/ml recombinant human hepatocyte growth factor (Gibco; Thermo Fisher Scientific, Inc. ). Cells were passaged after a confluent monolayer was obtained; subsequently, cells at passage were detached with EDTA/trypsin (1: 1; 0. 2% each) for 58 min (Gibco; Thermo Fisher Scientific, Inc., ) and re-seeded in fresh culture medium. Cells were stained with hematoxylin-eosin (HE; Sigma-Aldrich, St . Louis, MO, USA) using a standard protocol (hematoxylin for.