Biliary Cells Research Articles

Abstract 2110: WEE1 inhibition could reverse trastuzumab resistance by downregulation of PD-L1 in HER2-positive cancers

Abstract Background: Trastuzumab in combination with chemotherapy is a standard of care for patients with HER2-positive breast and gastric cancer. Resistance mechanism to trastuzumab, anti-HER2 therapy, includes multiple pathways. Cancer cells could evade immune surveillance through high expression of programmed cell death ligand 1 (PD-L1) on cancer or immune cells. Among resistance mechanisms to trastuzumab, the role of PD-L1 modulation has not yet been discovered in HER2-positive cancers. WEE1 is involved in cell cycle progression and DNA damage response (DDR), and, interestingly, beyond DDR, it could modulate immunes. We aimed to evaluate the role of PD-L1 in trastuzumab resistance in HER2-positive cancers with/without immune cells and to explore WEE1 inhibitor as a trastuzumab resistance overcoming strategy by modulation of PD-L1. Methods: Four trastuzumab-resistant (HR) cells (SNU216HR, N87HR, SNU2670HR, SNU2773HR) were established from 2 HER2-amplified gastric cancer cells (SNU216, NCI-N87) and 2 HER2-amplified biliary tract cancer cells (SNU2670, SNU2773). For WEE1 inhibition, AZD1775 was used. MTT assay, colony formation assay, cell cycle analysis by FACS Calibur flow cytometer, and western blot were done. Results: All four HR cells showed PD-L1 upregulation compared with parental cells. When PD-L1 was knocked-down by transfection with si-PD-L1, anti-growth/proliferation effects were observed in MTT assay and colony forming assay. PD-L1 itself may promote cancer cell growth without interacting with immune cells. AZD1775 downregulated PD-L1 expression and induced cell cycle arrest at sub-G1 and G2/M phases in all 4 HR cells. The synergistic anti-proliferative effects were found in all 4 HR cells with co-treatment of trastuzumab and AZD1775. Conclusion: PD-L1 upregulation may contribute to trastuzumab resistance in HER2-positive cancer cells. Targeting WEE1-PD-L1 pathway might be a candidate strategy to overcome trastuzumab resistance in HER2-positive cancers. Citation Format: Meihua Jin, Ah-Rong Nam, Ji-Eun Park, Ju-Hee Bang, Kyoung-Seok Oh, Do-Youn Oh, Yung-Jue Bang. WEE1 inhibition could reverse trastuzumab resistance by downregulation of PD-L1 in HER2-positive cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2110.

Abstract 4875: Clinical importance and clarification of the WHO subclassification of combined hepatocellular and cholangiocarcinoma

Abstract Introduction: Combined hepatocellular and cholangiocarcinoma, classical type (Comb HCC-CCC) is defined as a single tumor, in which hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) are clearly differentiated. However, combined hepatocellular-cholangiocarcinoma with stem-cell features, cholangiolocellular type (CoCC) was added to the WHO Classification in 2010. This has caused a great deal of confusion and raised many questions for clinicians and pathologists. The aim of this study was to answer these questions and evaluate the clinical importance of the WHO classification. Subjects: The subjects were 1,002 patients with primary liver cancer who underwent hepatectomy from 2010 to 2016, including 931 with HCC, 6 with Comb HCC-CCC, 50 with ICC, and 15 with CoCC. Pathological evaluation using immunohistochemical staining was mainly used for CoCC. Results: The CoCC cases had similar serum total bilirubin and serum albumin to those in other types of hepatic cancer, but with a low ICGR15 level. AFP, PIVKA-II, and CEA were 4.4 (1.3 - 3,689) ng/mL, 18 (9 - 15,933) mAU/mL, and 3.8 (0.2 - 33) ng/mL, respectively. In preoperative CT diagnosis of CoCC, HCC, Comb HCC-CCC, and ICC were diagnosed in 20%, 40%, and 40% of the cases, respectively, suggesting difficulty with this diagnosis. The resected specimen showed the number of tumors (1 [1 - 16]), tumor diameter (4 [1.7 - 12] cm), microscopic-portal venous invasion (43%), microscopic venous invasion (36%), and cirrhosis (22%), suggesting a higher level of invasion to vascular channels compared to other types of cancer. In pathological findings, both transitional HCC and cholangiocarcinoma were found in HE staining, in addition to fibrosis and necrosis in the tumor. Among the subjects, 40%, 100%, 100%, and 100% had biliary cell markers of positive CD117 (c-Kit), positive CD56 (NCAM), positive CK7, and positive CK19, respectively, in addition to high expression of neural cell adhesion molecules. Levels of hepatocytes (10%) and glypican 3 (25%) were low. Cumulative survival was lower than that in other types of liver cancer, with 1- and 3-year survival rates of 67% and 57%, respectively. [Conclusion] The development mechanism of Comb HCC-CCC is thought to be genetic transformation of HCC or ICC, while that of CoCC with stem-cell features is believed to be cancerization of stem cells. However, stem-cell features are just characteristics, and thus do not serve as definitive evidence for stem cell-derived cancer. In addition, since there are various types of CoCC in Comb HCC-CCC, actual classification is extremely difficult in many cases. The clinical importance of clear differentiation between Comb HCC-CCC and CoCC is unclear, and thus the WHO classification of these tumors may be in a transition period. Citation Format: Hisashi NAKAYAMA, Tadatoshi TAKAYAMA, Yutaka Midorikawa, Masahiko Sugitani. Clinical importance and clarification of the WHO subclassification of combined hepatocellular and cholangiocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4875.

The descending pathophysiology model of cholestatic liver disease

Intrahepatic cholestasis is a pathological condition in which the synthesis, secretion, and excretion of bile are blocked, and thus the bile does not flow normally into the duodenum and bloodstream. According to cytological damage site, it can be divided into hepatocellular cholestasis, biliary duct cell cholestasis and mixed cell cholestasis. The two kinds of pathophysiological models [ascending or upstream (damage begins with cholangiocytes and then extends to the hepatocytes) and descending or downstream (the damage starts from the liver cells and then extends to the bile duct cells)] has distinct features in the process of disease occurrence and development. This article mainly elaborates the "descending" pathophysiological model of cholestatic liver disease (hepatocytic damage progresses to biliary duct cell), and further explores its etiology, pathogenesis and treatment methods.

Novel biomarkers for primary biliary cholangitis to improve diagnosis and understand underlying regulatory mechanisms.

Primary biliary cholangitis is an autoimmune biliary disease characterized by injury of bile ducts, eventually leading to cirrhosis and death. In most cases, anti-mitochondrial antibodies and persistently elevated serum alkaline phosphatase are the basis for the serological diagnosis.Anti-nuclear antibodies are also useful and may indicate a more aggressive diseases course. In patients in which anti-mitochondrial antibodies are not detected, an accurate diagnosis requires liver histology. This study aims at identifying specific biomarkers for the serological diagnosis of primary biliary cholangitis. Sera from patients affected by primary biliary cholangitis, primary sclerosing cholangitis, hepatitis C virus (with and without cryoglobulinemia), hepatocarcinoma and healthy donors were tested on a protein array representing 1658 human proteins. The most reactive autoantigens were confirmed by DELFIA analysis on expanded cohorts of the same mentioned serum classes, and on autoimmune hepatitis sera, using anti-PDC-E2 as reference biomarker. Two autoantigens, SPATA31A3 and GARP, showed high reactivity with primary biliary cholangitis sera, containing or not anti-mitochondrial antibodies. Their combination with PDC-E2 allowed to discriminate primary biliary cholangitis from all tested control classes with high sensitivity and specificity. We found that GARP expression is upregulated upon exposure to biliary salts in human cholangiocytes, an event involving EGFR and insulin pathways. GARP expression was also detected in biliary duct cells of PBC patients. This study highlighted SPATA31A3 and GARP as new biomarkers for primary biliary cholangitis and unravelled molecular stimuli underlying GARP expression in human cholangiocytes.

Generation of Organoids from Mouse Extrahepatic Bile Ducts.

Cholangiopathies, which affect extrahepatic bile ducts (EHBDs), include biliary atresia, primary sclerosing cholangitis, and cholangiocarcinoma. They have no effective therapeutic options. Tools to study EHBD are very limited. Our purpose was to develop an organ-specific, versatile, adult stem cell-derived, preclinical cholangiocyte model that can be easily generated from wild type and genetically engineered mice. Thus, we report on the novel technique of developing an EHBD organoid (EHBDO) culture system from adult mouse EHBDs. The model is cost-efficient, able to be readily analyzed, and has multiple downstream applications. Specifically, we describe the methodology of mouse EHBD isolation and single cell dissociation, organoid culture initiation, propagation, and long-term maintenance and storage. This manuscript also describes EHBDO processing for immunohistochemistry, fluorescent microscopy, and mRNA abundance quantitation by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). This protocol has significant advantages in addition to producing EHBD-specific organoids. The use of a conditioned medium from L-WRN cells significantly reduces the cost of this model. The use of mouse EHBDs provides almost unlimited tissue for culture generation, unlike human tissue. Generated mouse EHBDOs contain a pure population of epithelial cells with markers of endodermal progenitor and differentiated biliary cells. Cultured organoids maintain homogenous morphology through multiple passages and can be recovered after a long-term storage period in liquid nitrogen. The model allows for the study of biliary progenitor cell proliferation, can be manipulated pharmacologically, and may be generated from genetically engineered mice. Future studies are needed to optimize culture conditions in order to increase plating efficiency, evaluate functional cell maturity, and direct cell differentiation. Development of co-culture models and a more biologically neutral extracellular matrix are also desirable.

An integrin-based nanoparticle that targets activated hepatic stellate cells and alleviates liver fibrosis

Activation of hepatic stellate cells (HSCs) contributes to the development of liver fibrosis. Because of a relatively small population of HSCs in the liver and the lack of specific membrane targeting proteins, HSC-targeted therapy remains a major clinical challenge. Here we first showed that a hallmark of activated HSC (aHSC) is their increased expression of integrin αvβ3. Thus we established sterically stable liposomes that contain the cyclic peptides (cRGDyK) with a high affinity to αvβ3 to achieve aHSC-specific delivery. Our results showed that the cRGDyK-guided liposomes were preferentially internalized by activated HSCs in vitro and in vivo, and the internalization was abolished by excess free cRGDyK or knockdown of αvβ3. In contrast, quiescent HSCs, hepatocytes, Kupffer cells, sinusoidal endothelial cells, or biliary cells showed minimal uptake of the cRGDyK-guided liposomes. When loaded with the hedgehog inhibitor vismodegib, the cRGDyK-guided liposomes inhibited hedgehog pathway signaling specifically in activated HSCs. Moreover, treatment of mice with vismodegib-loaded cRGDyK-liposomes markedly inhibited the fibrogenic phenotype in bile duct ligation- or thioacetamide-treated mice. We conclude that the cRGDyK-guided liposomes can specifically target the activated HSCs, but not quiescent HSCs. This nanoparticle system showed great promise to deliver therapeutic agents to aHSC to treat liver fibrosis.

Secretin/Secretin Receptor (Sct/SR) Signaling Promotes Biliary Senescence and Liver Fibrosis During Alcoholic Liver Disease

Chronic alcohol consumption can cause alcoholic liver disease (ALD) which evolves to cirrhosis at later stages. Ductular reaction characterized by extensive biliary cell proliferation, portal inflammation and fibrosis is observed in such conditions. Biliary senescence is increased during cholangiopathies, and leads to paracrine activation of hepatic stellate cells (HSCs) and increased liver fibrosis by changes in the Sct/MicroRNA (miR)‐125b‐dependent biliary release of TGF‐b1. Sct and SR are only expressed by cholangiocytes and the Sct/SR axis promotes biliary senescence through increased TGF‐b1 signaling. Damage to cholangiocytes and the role of Sct/SR signaling during ALD is unknown. Our aim is to characterize biliary cell damage, fibrosis, and the potential implications of biliary Sct/SR signaling during ALD.MethodsHuman samples from healthy and alcoholic steatohepatitis (ASH) patients were evaluated for: (i) Sct/SR/miR‐125b/TGF‐b1 axis and Sct serum levels, (ii) bile duct mass (IBDM), (iii) biliary senescence, (iv) Kupffer cell number, and (v) liver fibrosis as described below. In human samples, serum Sct levels were correlated with serum levels of total bilirubin (TBIL) and aspartate aminotransferase (AST), and MELD score. For in vivo studies, female wild‐type (WT), Sct−/−, SR−/− and Sct−/−/SR−/− (DKO) were ad libitum fed a 5% ethanol (EtOH) diet for 8 wks with a 31.5% EtOH gavage 1X/wk. Liver damage and steatosis were evaluated by H&E and Oil Red O staining. Biliary Sct/SR expression was visualized by immunostaining, and serum Sct levels by EIA. IBDM was evaluated by CK‐19 (biliary‐specific marker) staining. Biliary senescence was determined by immunostaining for p16, p21 and SA‐b‐Galactosidase. Kupffer cell number was evaluated by staining for F4/80. Liver fibrosis was determined by Sirius Red staining, and immunostaining for Collagen‐1a. HSC activation was visualized by staining for desmin (HSC marker) and a‐smooth muscle actin (a‐SMA, increased in activated HSCs). Biliary miR‐125b levels were determined by qPCR, and TGF‐b1 expression by staining.ResultsHuman ASH had increased biliary Sct/SR/miR‐125b/TGF‐b1 signaling, Sct secretion, IBDM, Kupffer cell number and liver fibrosis. Increased Sct serum levels positively correlated with serum TBIL and AST levels, and MELD score in ASH patients. WT EtOH mice had increased (i) liver damage/steatosis, (ii) biliary Sct/SR/miR‐125b/TGF‐b1 signaling and Sct secretion, (iii) IBDM and biliary senescence, (iv) Kupffer cell number, and (v) liver fibrosis/HSC activation compared to pair‐fed animals. These parameters were decreased in Sct−/−, SR−/− and DKO EtOH mice.ConclusionEnhanced biliary Sct/SR expression promotes biliary senescence and subsequent liver fibrosis during ALD progression via miR‐125b/TGF‐b1 signaling. Increased biliary Sct/SR expression correlates with increased liver damage in patients with ASH, eluding to the importance of biliary activation during ALD. Blocking Sct/SR signaling may be a therapeutic option for patients with ALD.Support or Funding InformationNIH NIDDK, NIH NIAAA, VA MeritThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A Role for Low Density Lipoprotein Receptor Related Protein 1 (LRP1) and Hepatocyte Nuclear Factor 4α (HNF4α) in Regulating Lipid Metabolism

IntroductionLiver is essential for maintaining healthy lipid, carbohydrate, and protein levels. The low density lipoprotein receptor related protein 1 (LRP1) is a multifunctional cell surface receptor that is expressed ubiquitously throughout the body on a variety of cell types. In liver, LRP1 is present on stellate cells, Kupffer cells, biliary cells, and hepatocytes (HEPs), where it is known to be one of the most abundant hepatocellular proteins. Among its many roles, LRP1 is believed to participate in lipoprotein metabolism. Recently, we found that aged mice with a conditional knockout (cKO) for hepatocellular LRP1 (LRP1−) are positive for LRP1 in HEPs that surround the periportal region. Further studies determined that a minor population of LRP1+ cells from younger cKO mice likely repopulates the aged livers over time; the number of periportal positive LRP1+ HEPs increases as the animals age. To determine if these LRP1+ and LRP1− HEPs are functionally different, we stained livers from aged animals for several different proteins and found that the hepatocellular transcription factor, HNF4α, a master regulator of hepatic function, was specifically absent in the LRP1− HEPs where lipids are abundant. Upon further investigation, we determined that in WT animals, LRP1 and HNF4α can form a complex that is present in both the nucleus and cytoplasm, leading us to hypothesize that LRP1 is capable of trafficking HNF4α as a means of regulating lipid metabolism. To begin to investigate this hypothesis, we took advantage of the plasminogen activator inhibitor type 1 (PAI‐1) knockout (KO) mouse as PAI‐1 is known to regulate the internalization of LRP1.MethodsTo confirm complex formation, immunoprecipitation (IP) was performed using total cell lysates from livers of PAI‐1 wild type (WT) and KO mice that were fed either normal chow (NC) or high fat diet (HFD). Next, cytoplasmic‐ and nuclear‐enriched extracts were prepared from these livers and probed by western blot to determine if diet affected complex location. Finally, immunohistochemistry (IHC) was used to localize the proteins.ResultsOverall complex formation was increased in the animals on the HFD, regardless of genotype. Similarly, less complex was found in the cytoplasms of animals on HFD, relative to their NC counterparts, regardless of genotype. Finally, localization of HNF4α was found to be regionalized in the PAI‐1 KOs on HFD, but not in their WT counterparts; HNF4α was present in areas of fat deposition in the PAI‐1 WT animals, but absent in the KOs, further implicating LRP1 in HNF4α trafficking.ConclusionThese findings confirm that LRP1 and HNF4α can form a complex, that diet affects quantity and location of the complex, and further indicates that LRP1 has a role in regulating nuclear localization of HNF4α. Further studies will be needed to elucidate the exact function of the complex, as well as its possible implications for lipid regulation and metabolism.Support or Funding InformationSarah Hoskings was supported by an SROPP award from ASIP as well as SURP funding from the family of Dr. William Zeiler.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Aging-Related Expression of Twinfilin-1 Regulates Cholangiocyte Biological Response to Injury.

Disorders of the biliary tree develop and progress differently according to patient age. It is currently not known whether the aging process affects the response to injury of cholangiocytes. The aim of this study was to identify molecular pathways associated with cholangiocyte aging and to determine their effects in the biological response to injury of biliary cells. A panel of microRNAs (miRs) involved in aging processes was evaluated in cholangiocytes of young and old mice (2 months and 22 months of age, respectively) and subjected to a model of sclerosing cholangitis. Intracellular pathways that are common to elevated miRs were identified by in silico analysis. Cell proliferation and senescence were evaluated in Twinfilin-1 (Twf1) knocked-down cells. In vivo, senescence-accelerated prone mice (Samp8, a model for accelerated aging), Twf1-/- , or their respective controls were subjected to DDC (3,5-diethoxycarbonyl-1,4-dihydrocollidine). Cholangiocytes from DDC-treated mice showed up-regulation of a panel of aging-related miRs. Twf1 was identified by in silico analysis as a common target of the up-regulated miRs. Twf1 expression was increased both in aged and diseased cholangiocytes, and in human cholangiopathies. Knock-down of Twf1 in cholangiocytes reduced cell proliferation. Senescence and senescence-associated secretory phenotype marker expression increased in Twf1 knocked-down cholangiocytes following pro-proliferative and pro-senescent (10-day lipopolysaccharide) stimulation. In vivo, Samp8 mice showed increased biliary proliferation, fibrosis, and Twf1 protein expression level, whereas Twf1-/- had a tendency toward lower biliary proliferation and fibrosis following DDC administration compared with control animals. Conclusion: We identified Twf1 as an important mediator of both cholangiocyte adaptation to aging processes and response to injury. Our data suggest that disease and aging might share common intracellular pathways.

Peribiliary Glands Are Key in Regeneration of the Human Biliary Epithelium After Severe Bile Duct Injury.

Peribiliary glands (PBG) are a source of stem/progenitor cells organized in a cellular network encircling large bile ducts. Severe cholangiopathy with loss of luminal biliary epithelium has been proposed to activate PBG, resulting in cell proliferation and differentiation to restore biliary epithelial integrity. However, formal evidence for this concept in human livers is lacking. We therefore developed an ex vivo model using precision‐cut slices of extrahepatic human bile ducts obtained from discarded donor livers, providing an intact anatomical organization of cell structures, to study spatiotemporal differentiation and migration of PBG cells after severe biliary injury. Postischemic bile duct slices were incubated in oxygenated culture medium for up to a week. At baseline, severe tissue injury was evident with loss of luminal epithelial lining and mural stroma necrosis. In contrast, PBG remained relatively well preserved and different reactions of PBG were noted, including PBG dilatation, cell proliferation, and maturation. Proliferation of PBG cells increased after 24 hours of oxygenated incubation, reaching a peak after 72 hours. Proliferation of PBG cells was paralleled by a reduction in PBG apoptosis and differentiation from a primitive and pluripotent (homeobox protein Nanog+/ sex‐determining region Y‐box 9+) to a mature (cystic fibrosis transmembrane conductance regulator+/secretin receptor+) and activated phenotype (increased expression of hypoxia‐inducible factor 1 alpha, glucose transporter 1, and vascular endothelial growth factor A). Migration of proliferating PBG cells in our ex vivo model was unorganized, but resulted in generation of epithelial monolayers at stromal surfaces. Conclusion: Human PBG contain biliary progenitor cells and are able to respond to bile duct epithelial loss with proliferation, differentiation, and maturation to restore epithelial integrity. The ex vivo spatiotemporal behavior of human PBG cells provides evidence for a pivotal role of PBG in biliary regeneration after severe injury.

The Cancer Stem Cell Inhibitor Napabucasin (BBI608) Shows General Cytotoxicity in Biliary Tract Cancer Cells and Reduces Cancer Stem Cell Characteristics.

Biliary tract cancer is a devastating disease with limited therapeutic options. The involvement of cancer stem cells in biliary tract cancer is likely. Napabucasin is a previously described cancer stem cell inhibitor that is currently being used in clinical trials. However, data regarding napabucasin and biliary tract cancer are not available yet. We tested the general cytotoxic effect of napabucasin on a comprehensive biliary tract cancer in vitro model, using resazurin assay and Annexin V/7-AAD staining. The effect of napabucasin on functional cancer stem cell characteristics was analyzed via soft agar assay, aldehyde-dehydrogenase-1 assay, measurement of surface CD326 expression, and measurement of clonogenic growth. The evaluation of the effect of napabucasin on cancer stem cell protein and gene expression was performed using Western blot and reverse transcription-PCR-based human cancer stem cell array. Napabucasin showed a concentration- and cell line-dependent cytotoxic effect, and increased the apoptotic and necrotic cell fractions. Treatment with napabucasin significantly reduced the formation of tumor spheres and clonogenic growth, as well as CD326 surface expression. Expression of cancer stem cell markers were reduced following napabucasin treatment on the protein and mRNA levels. Our study provides first data regarding napabucasin as a promising substance for the treatment of biliary tract cancer.

The FXR agonist obeticholic acid inhibits the cancerogenic potential of human cholangiocarcinoma.

Cholangiocarcinoma (CCA) is an aggressive cancer with high resistance to chemotherapeutics. CCA is enriched in cancer stem cells, which correlate with aggressiveness and prognosis. FXR, a member of the metabolic nuclear receptor family, is markedly down-regulated in human CCA. Our aim was to evaluate, in primary cultures of human intrahepatic CCA (iCCA), the effects of the FXR agonist obeticholic acid (OCA), a semisynthetic bile acid derivative, on their cancerogenic potential. Primary human iCCA cell cultures were prepared from surgical specimens of mucinous or mixed iCCA subtypes. Increasing concentrations (0–2.5 μM) of OCA were added to culture media and, after 3–10 days, effects on proliferation (MTS assay, cell population doubling time), apoptosis (annexin V-FITC/propidium iodide), cell migration and invasion (wound healing response and Matrigel invasion assay), and cancerogenic potential (spheroid formation, clonogenic assay, colony formation capacity) were evaluated. Results: FXR gene expression was downregulated (RT-qPCR) in iCCA cells vs normal human biliary tree stem cells (p < 0.05) and in mucinous iCCA vs mixed iCCA cells (p < 0.05) but was upregulated by addition of OCA. OCA significantly (p < 0.05) inhibited proliferation of both mucinous and mixed iCCA cells, starting at a concentration as low as 0.05 μM. Also, CDCA (but not UDCA) inhibited cell proliferation, although to a much lower extent than OCA, consistent with its different affinity for FXR. OCA significantly induced apoptosis of both iCCA subtypes and decreased their in vitro cancerogenic potential, as evaluated by impairment of colony and spheroid formation capacity and delayed wound healing and Matrigel invasion. In general, these effects were more evident in mixed than mucinous iCCA cells. When tested together with Gemcitabine and Cisplatin, OCA potentiated the anti-proliferative and pro-apoptotic effects of these chemotherapeutics, but mainly in mixed iCCA cells. OCA abolished the capacity of both mucinous and mixed iCCA cells to form colonies when administered together with Gemcitabine and Cisplatin. In subcutaneous xenografts of mixed iCCA cells, OCA alone or combined with Gemcitabine or Cisplatin markedly reduced the tumor size after 5 weeks of treatment by inducing necrosis of tumor mass and inhibiting cell proliferation. In conclusion, FXR is down-regulated in iCCA cells, and its activation by OCA results in anti-cancerogenic effects against mucinous and mixed iCCA cells, both in vitro and in vivo. The effects of OCA predominated in mixed iCCA cells, consistent with the lower aggressiveness and the higher FXR expression in this CCA subtype. These results, showing the FXR-mediated capacity of OCA to inhibit cholangiocarcinogenesis, represent the basis for testing OCA in clinical trials of CCA patients.

Molecular targeting of HER2-overexpressing biliary tract cancer cells with trastuzumab emtansine, an antibody-cytotoxic drug conjugate.

Trastuzumab emtansine (T-DM1) provides clinical benefit in breast cancers overexpressing human epidermal growth factor receptor 2 (HER2). However, its efficacy against biliary tract cancers (BTC) has not been evaluated. In this study, the effectiveness of T-DM1 in various BTC cell lines and xenograft models with different levels of HER2 expression was investigated. HER2 expression status in xenografts and patient tissue microarrays was assessed by immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH). Cell-surface HER2 expression levels and cell growth inhibition in response to T-DM1 were examined in 17 BTC cell lines. The antitumor activity of T-DM1 was evaluated in four xenograft mouse models with different levels of HER2 expression. The effects of T-DM1 on HER2 signaling, antibody-dependent cell-mediated cytotoxicity (ADCC), cell cycle, and apoptosis were assessed in vitro. Cell-surface expression of HER2 was observed in both gallbladder carcinoma and cholangiocarcinoma tissues. The anti-proliferative activity of T-DM1 was higher in BTC cell lines and breast cancer cell lines with higher levels of HER2 expression. The HER2 status (IHC score|HER2-to-CEP17 ratio by FISH testing) of each BTC xenograft was 3 +|8.3 for KMCH-1, 2 +|4.7 for Mz-ChA-1, 1 +/0|1.4 for OCUG-1, and 0|1.1 for KKU-100, and T-DM1 showed antitumor activity in proportion to the HER2 status. T-DM1 inhibited HER2 signaling and induced ADCC, mitotic arrest, and apoptosis in KMCH-1 cells. T-DM1 exhibited preclinical activity in HER2-overexpressing BTC. Further evaluation in clinical studies is warranted.

Downregulation of SPARC Is Associated with Epithelial-Mesenchymal Transition and Low Differentiation State of Biliary Tract Cancer Cells

Background: Biliary tract cancers (BTCs) have a poor prognosis. BTCs are characterized by a prominent desmoplastic reaction which possibly contributes to the aggressive phenotype of this tumor. The desmoplastic reaction includes excessive production and deposition of extracellular matrix proteins such as periostin, secreted protein acidic and rich in cysteine (SPARC), thrombospondin-1, as well as accumulation of α-smooth muscle actin-positive cancer-associated fibroblasts and immune cells, secreting growth factors and cytokines including transforming growth factor (TGF)-β. In the present study, we investigated the expression of SPARC in BTC as well as its possible regulation by TGF-β. Methods: Expression levels of Sparc, TGF-β1 and its receptor ALK5 were evaluated by quantitative real-time PCR in 6 biliary tract cell lines as well as 1 immortalized cholangiocyte cell line (MMNK-1). RNAs from tumor samples of 7 biliary tract cancer patients were analyzed for expression of Sparc, TGF-β type II receptor (TbRII) as well as Twist and ZO-1. MMNK-1 cells were stimulated with TGF-β for 24 h, and Sparc, ZO-1 and E-Cadherin expressions were determined. The presence of SPARC protein was analyzed by immunohistochemistry in tumor specimens from 10 patients. Results: When comparing basal Sparc transcript levels in diverse BTC cell lines to MMNK-1 cells, we found that it was strongly downregulated in all cancer cell lines. The remaining expression levels were higher in highly differentiated cell lines (CCSW1, MZChA1, MZChA2 and TFK-1) than in less differentiated and undifferentiated ones (BDC, SKChA1). Expression of Sparc in BTC patient samples showed a significant positive correlation with expression of the epithelial marker ZO-1. In contrast, the mesenchymal marker Twist and the TbRII showed a trend of negative correlation with expression of Sparc in these samples. TGF-β exposure significantly downregulated Sparc expression in MMNK-1 cholangiocytes in vitro in parallel to downregulation of epithelial markers (E-Cadherin and ZO-1). Finally, SPARC immunostaining was performed in 10 patient samples, and the correlation between absence of SPARC and survival times was analyzed. Conclusions: These data imply that a decrease in SPARC expression is correlated with dedifferentiation of BTC cells resulting in enhanced EMT being possibly mediated by TGF-β. Thereby SPARC levels might be a marker for individual prognosis of a patient, and strategies aiming at inhibition of SPARC downregulation might have potential for new future therapies.

An improved and easy protocol for primary epithelial cell culture from atretic tissue in biliary atresia.

Biliary atresia (BA) is a lethal disease of infancy with obscure etiology. Insight into the pathogenesis of this disorder is limited by lack of availability of adequate epithelial tissue. Primary culture of human biliary epithelium may help to provide material for diagnostic and research purposes. However, culture of these cells from atretic tissue is a challenging task. We aimed to develop a reliable and easier protocol for culture of human biliary epithelial cells from excised atretic extrahepatic bile duct. An explant culture was performed using tissue obtained from 30 children with diseases of biliary tract. The culture showed florid cell growth in less than 3 weeks. Epithelial nature and biliary origin of cultured cells was confirmed using pancytokeratin and cytokeratin -7 antibodies. The protocol showed 100% success rate as cells could be cultured in all 30 patients. Moreover, the cells remained viable for a duration of over 3 months in most of the cases. This easier culture technique is likely to have an impact on the study of biliary cell pathophysiology, particularly in BA.

Patient-Derived Organoids from Human Bile: An In Vitro Method to Study Cholangiopathies.

Cholangiopathies, including primary sclerosing cholangitis, are a group of heterogeneous diseases characterized by inflammation and fibrosis of the intrahepatic and extrahepatic bile duct epithelium. Studies, especially of primary sclerosing cholangitis, have been hampered by the difficulty in accessing the cholangiocyte, instability of in vitro culture systems, and reliance on (limited) samples from end-stage disease. Here we describe a novel method of culturing biliary cells from bile of primary sclerosing cholangitis patients undergoing endoscopic retrograde cholangiopancreatography for clinical indications. These 3D organoid cultures demonstrate a biliary phenotype, can be maintained in vitro, and biobanked for future analyses. Given the need for diagnostic and therapeutic endoscopic retrograde cholangiopancreatography throughout the disease in many primary sclerosing cholangitis patients, this method can provide longitudinal studies in individual patients, allowing for a correlation of gene expression with disease status. These organoids can react to inflammatory stimuli, resulting in the secretion of chemo/cytokines indicative of the reactive immune phenotype characteristic of primary sclerosing cholangitis. Therefore, bile-derived organoids provide a model to study the pathogenesis and pharmacotherapeutic treatment of cholangiopathies.

Spatial patterning of liver progenitor cell differentiation mediated by cellular contractility and Notch signaling.

The progenitor cells of the developing liver can differentiate toward both hepatocyte and biliary cell fates. In addition to the established roles of TGFβ and Notch signaling in this fate specification process, there is increasing evidence that liver progenitors are sensitive to mechanical cues. Here, we utilized microarrayed patterns to provide a controlled biochemical and biomechanical microenvironment for mouse liver progenitor cell differentiation. In these defined circular geometries, we observed biliary differentiation at the periphery and hepatocytic differentiation in the center. Parallel measurements obtained by traction force microscopy showed substantial stresses at the periphery, coincident with maximal biliary differentiation. We investigated the impact of downstream signaling, showing that peripheral biliary differentiation is dependent not only on Notch and TGFβ but also E-cadherin, myosin-mediated cell contractility, and ERK. We have therefore identified distinct combinations of microenvironmental cues which guide fate specification of mouse liver progenitors toward both hepatocyte and biliary fates.

Liver Regeneration: Different Sub-Populations of Parenchymal Cells at Play Choreographed by an Injury-Specific Microenvironment.

Liver regeneration is crucial for the maintenance of liver functional mass during homeostasis and diseases. In a disease context-dependent manner, liver regeneration is contributed to by hepatocytes or progenitor cells. As long as they are replicatively competent, hepatocytes are the main cell type responsible for supporting liver size homeostasisand regeneration. The concept that all hepatocytes within the lobule have the same proliferative capacity but are differentially recruited according to the localization of the wound, or whether a yet to be defined sub-population of hepatocytes supports regeneration is still debated. In a chronically or severely injured liver, hepatocytes may enter a state of replicative senescence. In such conditions, small biliary cells activate and expand, a process called ductular reaction (DR). Work in the last few decades has demonstrated that DR cells can differentiate into hepatocytes and thereby contribute to parenchymal reconstitution. In this study we will review the molecular mechanisms supporting these two processes to determine potential targets that would be amenable for therapeutic manipulation to enhance liver regeneration.

Hedgehog Signaling Modulates Interleukin-33-Dependent Extrahepatic Bile Duct Cell Proliferation in Mice.

Hedgehog (HH) signaling participates in hepatobiliary repair after injury and is activated in patients with cholangiopathies. Cholangiopathies are associated with bile duct (BD) hyperplasia, including expansion of peribiliary glands, the niche for biliary progenitor cells. The inflammation‐associated cytokine interleukin (IL)‐33 is also up‐regulated in cholangiopathies, including cholangiocarcinoma. We hypothesized that HH signaling synergizes with IL‐33 in acute inflammation‐induced BD hyperplasia. We measured extrahepatic BD (EHBD) thickness and cell proliferation with and without an IL‐33 challenge in wild‐type mice, mice overexpressing Sonic HH (pCMV‐Shh), and mice with loss of the HH pathway effector glioma‐associated oncogene 1 (Gli1lacZ/lacZ). LacZ reporter mice were used to map the expression of HH effector genes in mouse EHBDs. An EHBD organoid (BDO) system was developed to study biliary progenitor cells in vitro. EHBDs from the HH overexpressing pCMV‐Shh mice showed increased epithelial cell proliferation and hyperplasia when challenged with IL‐33. In Gli1lacZ/lacZ mice, we observed a decreased proliferative response to IL‐33 and decreased expression of Il6. The HH ligands Shh and Indian HH (Ihh) were expressed in epithelial cells, whereas the transcriptional effectors Gli1, Gli2, and Gli3 and the HH receptor Patched1 (Ptch1) were expressed in stromal cells, as assessed by in situ hybridization and lacZ reporter mice. Although BDO cells lacked canonical HH signaling, they expressed the IL‐33 receptor suppression of tumorigenicity 2. Accordingly, IL‐33 treatment directly induced BDO cell proliferation in a nuclear factor κB‐dependent manner. Conclusion: HH ligand overexpression enhances EHBD epithelial cell proliferation induced by IL‐33. This proproliferative synergism of HH and IL‐33 involves crosstalk between HH ligand‐producing epithelial cells and HH‐responding stromal cells.

Loss of trefoil factor 1 inhibits biliary regeneration but accelerates the hepatic differentiation of progenitor cells in mice

Although the regeneration of the adult liver depends on hepatic progenitor cells (HPCs), many uncertainties regarding hepatic regeneration in the injured liver remain. Trefoil factor family 1 (TFF1), a secretory protein predominantly expressed in the gastrointestinal tract, is responsible for mucosal restitution. Here, we investigated the role of TFF1 in liver regeneration using a mouse model of hepatic injury (choline-deficient ethionine-supplemented diet and carbon tetrachloride administration) and genetically engineered mice (TFF1 knockout (TFF1−/−)). Immunohistochemistry analysis of human liver samples revealed TFF1 expression in the hepatocytes close to ductular reaction and the regenerating biliary epithelium in injured liver. The number of cytokeratin 19 (CK19)-positive bile ducts was significantly decreased in the TFF1−/− mice after liver injury. Notch pathway in the TFF1−/− mice was also downregulated. HPCs in the control mice differentiated into biliary cells (CK19+/SRY HMG box 9 (SOX9)+) more frequently. In contrast, HPCs in the TFF1−/− mice more frequently differentiated into a hepatic lineage (alpha fetoprotein+/SOX9+) after acute liver damage. Hepatocyte proliferation was upregulated, and the liver weight was increased in TFF1−/− mice in response to chronic liver damage. Thus, TFF1 is responsible for liver regeneration after liver injury by promoting HPC differentiation into a biliary lineage and inhibiting HPC differentiation into a hepatic lineage.