Molecular pathogenesis of cholangiocarcinoma

Gastrointestinal tumors and infectious agents: A wide field to explore

Infection is currently one of the main contributors to carcinogenesis. In fact, the International Agency for Research on Cancer has categorized eleven biological agents as group I carcinogens. It is estimated that around 16% of the 12.7 million new cancers diagnosed in 2008 were attributable to infectious agents. Although underdeveloped regions carry the highest incidence rates, about 7.4% of infection-related cancer cases occur in developed areas. Physicians are increasingly aware of the potential carcinogenic role of common virus like the Human Papilloma virus in cervical cancer, or the hepatitis B and C viruses in hepatocarcinoma. However, the carcinogenic role of several other infectious agents is less recognized. Given that gastrointestinal malignancies carry an overall poor prognosis, a better understanding of the carcinogenic mechanisms triggered by infectious agents is key to decrease the rate of cancer related deaths. Preventive measures directed to such infections would ideally impact survival. In this paper we review the main pathogenic mechanisms related to the development of gastrointestinal malignancies induced by infectious microorganisms and other pathogens which are currently under investigation.

Microbiome in human cancers

A microbiome is defined as the aggregate of all microbiota that reside in human digestive system and other tissues. This microbiota includes viruses, bacteria, fungi that live in various human organs and tissues like stomach, guts, oesophagus, mouth cavity, urinary tract, vagina, lungs, and skin. Almost 20 % of malignant cancers worldwide are related to microbial infections including bacteria, parasites, and viruses. The human body is constantly being attacked by microbes during its lifetime and microbial pathogens that have tumorigenic effects in 15-20 % of reported cancer cases. Recent scientific advances and the discovery of the effect of microbes on cancer as a pathogen or as a drug have significantly contributed to our understanding of the complex relationship between microbiome and cancer. The aim of this study is to overview some microbiomes that reside in the human body and their roles in cancer.

Transcriptomic profiling of three-dimensional cholangiocyte spheroids long term exposed to repetitive Clonorchis sinensis excretory-secretory products

Background

Biliary tract infection with the carcinogenic human liver fluke, Clonorchis sinensis, provokes chronic inflammation, epithelial hyperplasia, periductal fibrosis, and even cholangiocarcinoma. Complications are proportional to the intensity and duration of the infection. In addition to mechanical irritation of the biliary epithelia from worms, their excretory-secretory products (ESPs) cause chemical irritation, which leads to inflammation, proliferation, and free radical generation.

Methods

A three-dimensional in vitro cholangiocyte spheroid culture model was established, followed by ESP treatment. This allowed us to examine the intrinsic pathological mechanisms of clonorchiasis via the imitation of prolonged and repetitive in vivo infection.

Results

Microarray and RNA-Seq analysis revealed that ESP-treated cholangiocyte H69 spheroids displayed global changes in gene expression compared to untreated spheroids. In ESP-treated H69 spheroids, 185 and 63 probes were found to be significantly upregulated and downregulated, respectively, corresponding to 209 genes (p < 0.01, fold change > 2). RNA-Seq was performed for the validation of the microarray results, and the gene expression patterns in both transcriptome platforms were well matched for 209 significant genes. Gene ontology analysis demonstrated that differentially expressed genes were mainly classified into immune system processes, the extracellular region, and the extracellular matrix. Among the upregulated genes, four genes (XAF1, TRIM22, CXCL10, and BST2) were selected for confirmation using quantitative RT-PCR, resulting in 100% similar expression patterns in microarray and RNA-Seq.

Conclusions

These findings broaden our understanding of the pathological pathways of liver fluke-associated hepatobiliary disorders and suggest a novel therapeutic strategy for this infectious cancer.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04717-2.

Anti-Proliferative Effects of Compound A and Its Effect in Combination with Cisplatin in Cholangiocarcinoma Cells

BACKGROUND

Cholangiocarcinoma (CCA) is a fatal cancer with high resistance to anticancer drugs.  The development of new drugs or compounds to be used alone or in combination with currently available chemotherapeutic agents to improve the treatment of CCA is needed. Compound A (CpdA), which is a small plant-derived glucocorticoid receptor modulator, strongly inhibited the growth and survival of several cancers.  However, the effect of CpdA on cholangiocarcinoma has not been elucidated. The aim of this study was to investigate the effect of CpdA on CCA.

METHODS

Cytotoxicity of CpdA was tested in primary cells including peripheral blood mononuclear cells (PBMCs), fibroblasts, and human umbilical vein endothelial cells (HUVECs), as well as on CCA cell lines (KKU-100, KKU-055, and KKU-213) was examined. Cell cycle distribution and IL-6 expression was assessed by flow cytometry and real-time polymerase chain reaction, respectively.  The effect of combination CpdA and cisplatin was evaluated by cell viability assay.

RESULTS

CpdA significantly inhibited cell cycle at G1 phase in CCA cell lines, and reduced IL-6 mRNA expression.  However, combination CpdA and cisplatin did not enhance the inhibitory effect. TGFβR-II expression was increased in CCA cells after the combination treatment.

CONCLUSIONS

These results indicate the potential of CpdA for CCA treatment. However, combination treatment with CpdA and cisplatin increased CCA cell survival. The molecular mechanism is likely attributable to promotes cell survival via the TGFβR-II signaling pathway. The combination of CpdA with other anticancer drugs for CCA treatment should be further examined.

Long Non-Coding RNAs in Biliary Tract Cancer-An Up-to-Date Review

The term long non-coding RNA (lncRNA) describes non protein-coding transcripts with a length greater than 200 base pairs. The ongoing discovery, characterization and functional categorization of lncRNAs has led to a better understanding of the involvement of lncRNAs in diverse biological and pathological processes including cancer. Aberrant expression of specific lncRNA species was demonstrated in various cancer types and associated with unfavorable clinical characteristics. Recent studies suggest that lncRNAs are also involved in the development and progression of biliary tract cancer, a rare disease with high mortality and limited therapeutic options. In this review, we summarize current findings regarding the manifold roles of lncRNAs in biliary tract cancer and give an overview of the clinical and molecular consequences of aberrant lncRNA expression as well as of underlying regulatory functions of selected lncRNA species in the context of biliary tract cancer.

Clonorchis sinensis excretory-secretory products increase malignant characteristics of cholangiocarcinoma cells in three-dimensional co-culture with biliary ductal plates

Clonorchis sinensis is a carcinogenic human liver fluke, prolonged infection which provokes chronic inflammation, epithelial hyperplasia, periductal fibrosis, and even cholangiocarcinoma (CCA). These effects are driven by direct physical damage caused by the worms, as well as chemical irritation from their excretory-secretory products (ESPs) in the bile duct and surrounding liver tissues. We investigated the C. sinensis ESP-mediated malignant features of CCA cells (HuCCT1) in a three-dimensional microfluidic culture model that mimics an in vitro tumor microenvironment. This system consisted of a type I collagen extracellular matrix, applied ESPs, GFP-labeled HuCCT1 cells and quiescent biliary ductal plates formed by normal cholangiocytes (H69 cells). HuCCT1 cells were attracted by a gradient of ESPs in a concentration-dependent manner and migrated in the direction of the ESPs. Meanwhile, single cell invasion by HuCCT1 cells increased independently of the direction of the ESP gradient. ESP treatment resulted in elevated secretion of interleukin-6 (IL-6) and transforming growth factor-beta1 (TGF-β1) by H69 cells and a cadherin switch (decrease in E-cadherin/increase in N-cadherin expression) in HuCCT1 cells, indicating an increase in epithelial-mesenchymal transition-like changes by HuCCT1 cells. Our findings suggest that C. sinensis ESPs promote the progression of CCA in a tumor microenvironment via the interaction between normal cholangiocytes and CCA cells. These observations broaden our understanding of the progression of CCA caused by liver fluke infection and suggest a new approach for the development of chemotherapeutic for this infectious cancer.

The oriental liver fluke, Clonorchis sinensis, is a biological carcinogen of humans and is the cause of death of infectious cancer patients in China and Korea. Its chronic infection promotes cholangiocarcinogenesis due to direct contact of host tissues with the worms and their excretory-secretory products (ESPs); however, the specific mechanisms underlying this pathology remain unclear. To assess its contribution to the progression of cholangiocarcinoma (CCA), we developed a 3-dimensional (3D) in vitro culture model that consists of CCA cells (HuCCT1) in direct contact with normal cholangiocytes (H69), which are subsequently exposed to C. sinensis ESPs; therefore, this model represents a C. sinensis-associated CCA microenvironment. Co-cultured HuCCT1 cells exhibited increased motility in response to C. sinensis ESPs, suggesting that this model may recapitulate some aspects of tumor microenvironment complexity. Proinflammatory cytokines such as IL-6 and TGF-β1 secreted by H69 cells exhibited a crosstalk effect regarding the epithelial-mesenchymal transition of HuCCT1 cells, thus, promoting an increase in the metastatic characteristics of CCA cells. Our findings enable an understanding of the mechanisms underlying the etiology of C. sinensis-associated CCA, and, therefore, this approach will contribute to the development of new strategies for the reduction of its high mortality rate.

The immune milieu of cholangiocarcinoma: From molecular pathogenesis to precision medicine

Cholangiocarcinoma (CCA) is a deadly cancer of the biliary epithelium with limited therapeutic options. It is a heterogeneous group of cancer that could develop at any level from the biliary tree and is currently classified into intrahepatic, perihilar and distal based on its anatomical location. With incidence and mortality rates currently increasing, it is now the second most common type of primary liver cancer and represents up to 3% of all gastrointestinal malignancies. High-throughput genomics and epigenomics have greatly increased our understanding of CCA underlying biology, however its pathogenesis remains largely unknown. CCA is characterized by a highly desmoplastic microenvironment containing stromal cells, mainly cancer-associated fibroblasts, infiltrating tumor epithelium. Tumor microenvironment in CCA is a highly dynamic environment that, besides stromal and endothelial cells, encompass also an abundance of immune cells, of both the innate and adaptive immune system (including tumor-associated macrophages, neutrophils, natural killer cells, and T and B lymphocytes) and abundant proliferative factors. It is orchestrated by multiple soluble factors and signals, that eventually define a tumor growth-permissive microenvironment. Through complicate interactions with CCA cells, tumor microenvironment profoundly affects the proliferative and invasive abilities of epithelial cancer cells and plays an important role in accelerating neovascularization and preventing apoptosis of neoplastic cells. In this review, we discuss recent developments regarding the characteristics of the tumor microenvironment, the role of each cellular population, and their multiarticulate interaction with the malignant population. Further we discuss innovative treatment approaches, including immunotherapy, and how identification of CCA secreted factors by both the stromal component and immune cell subsets are leading towards a precision medicine in CCA.

Molecular Pathogenesis of Cholangiocarcinoma

BACKGROUND

Cholangiocarcinomas are a heterogeneous group of malignancies arising from a number of cells of origin along the biliary tree. Although most cases in Western countries are sporadic, large population-based studies have identified a number of risk factors. This review summarises the evidence behind reported risk factors and current understanding of the molecular pathogenesis of cholangiocarcinoma, with a focus on inflammation and cholestasis as the driving forces in cholangiocarcinoma development.

RISK FACTORS FOR CHOLANGIOCARCINOGENESIS

Cholestatic liver diseases (e.g. primary sclerosing cholangitis and fibropolycystic liver diseases), liver cirrhosis, and biliary stone disease all increase the risk of cholangiocarcinoma. Certain bacterial, viral or parasitic infections such as hepatitis B and C and liver flukes also increase cholangiocarcinoma risk. Other risk factors include inflammatory disorders (such as inflammatory bowel disease and chronic pancreatitis), toxins (e.g. alcohol and tobacco), metabolic conditions (diabetes, obesity and non-alcoholic fatty liver disease) and a number of genetic disorders.

MOLECULAR PATHOGENESIS OF CHOLANGIOCARCINOMA

Regardless of aetiology, most risk factors cause chronic inflammation or cholestasis. Chronic inflammation leads to increased exposure of cholangiocytes to the inflammatory mediators interleukin-6, Tumour Necrosis Factor-ɑ, Cyclo-oxygenase-2 and Wnt, resulting in progressive mutations in tumour suppressor genes, proto-oncogenes and DNA mismatch-repair genes. Accumulating bile acids from cholestasis lead to reduced pH, increased apoptosis and activation of ERK1/2, Akt and NF-κB pathways that encourage cell proliferation, migration and survival. Other mediators upregulated in cholangiocarcinoma include Transforming Growth Factor-β, Vascular Endothelial Growth Factor, Hepatocyte Growth Factor and several microRNAs. Increased expression of the cell surface receptor c-Met, the glucose transporter GLUT-1 and the sodium iodide symporter lead to tumour growth, angiogenesis and cell migration. Stromal changes are also observed, resulting in alterations to the extracellular matrix composition and recruitment of fibroblasts and macrophages that create a microenvironment promoting cell survival, invasion and metastasis.

CONCLUSION

Regardless of aetiology, most risk factors for cholangiocarcinoma cause chronic inflammation and/or cholestasis, leading to the activation of common intracellular pathways that result in reactive cell proliferation, genetic/epigenetic mutations and cholangiocarcinogenesis. An understanding of the molecular pathogenesis of cholangiocarcinoma is vital when developing new diagnostic biomarkers and targeted therapies for this disease.

Fibroinflammatory Liver Injuries as Preneoplastic Condition in Cholangiopathies

The cholangipathies are a class of liver diseases that specifically affects the biliary tree. These pathologies may have different etiologies (genetic, autoimmune, viral, or toxic) but all of them are characterized by a stark inflammatory infiltrate, increasing overtime, accompanied by an excess of periportal fibrosis. The cellular types that mount the regenerative/reparative hepatic response to the damage belong to different lineages, including cholagiocytes, mesenchymal and inflammatory cells, which dynamically interact with each other, exchanging different signals acting in autocrine and paracrine fashion. Those messengers may be proinflammatory cytokines and profibrotic chemokines (IL-1, and 6; CXCL1, 10 and 12, or MCP-1), morphogens (Notch, Hedgehog, and WNT/β-catenin signal pathways) and finally growth factors (VEGF, PDGF, and TGFβ, among others). In this review we will focus on the main molecular mechanisms mediating the establishment of a fibroinflammatory liver response that, if perpetuated, can lead not only to organ dysfunction but also to neoplastic transformation. Primary Sclerosing Cholangitis and Congenital Hepatic Fibrosis/Caroli’s disease, two chronic cholangiopathies, known to be prodrome of cholangiocarcinoma, for which several murine models are also available, were also used to further dissect the mechanisms of fibroinflammation leading to tumor development.

Global identification and characterization of lncRNAs that control inflammation in malignant cholangiocytes

BACKGROUND

Long noncoding RNAs (lncRNAs) are known to play important roles in different cell contexts, including cancers. However, little is known about lncRNAs in cholangiocarcinoma (CCA), a cholangiocyte malignancy with poor prognosis, and associated with chronic inflammation and damage to the biliary epithelium. This study determined whether lncRNAs were dysregulated and participated in disease diagnosis or pivotal inflammation pathways through a genome-wide lncRNA screening and functional analysis.

RESULTS

We firstly identified a large number of lncRNAs abnormally expressed between 9 pairs of cancerous and adjacent tissues of CCA, and between intra-hepatic CCA and extra-hepatic CCA through a genome-wide profiling. A set of aberrant differentially expressed lncRNAs were further validated in a training set (16 pairs) and a test set (11 pairs) of CCA patient samples. Following assessment of the diagnostic value of the 7 differentially expressed lncRNAs, we confirmed the optimal combination of H19, C3P1, AC005550.3, PVT1, and LPAL2 with area under the curve of 0.8828 [95% CI: 0.7441-1.021, P < 0.001], with 93.75% sensitivity and 81.25% specificity, at the cutoff point of - 0.2884 to distinguish the CCA tissue from the normal ones, suggesting that specific lncRNAs may have potential for detecting CCA. More importantly, the genome-wide locus and lncRNA/mRNA co-expression analyses revealed a set of lncRNAs that participated in inflammation and oxidative stress response pathways by regulating genes in cis or in trans. Finally, APOC1P1, PVT1, and LPAL2 were validated to regulate the migration and some pivotal inflammation genes under the CCA pathogenesis.

CONCLUSIONS

Our findings are the first to show that lncRNAs may not only be potential biomarkers of CCA progression but also respond to inflammation in CCA.

The Role of Stroma in Cholangiocarcinoma: The Intriguing Interplay between Fibroblastic Component, Immune Cell Subsets and Tumor Epithelium

Cholangiocarcinoma (CCA) is a severe and mostly intractable adenocarcinoma of biliary epithelial cells. A typical feature of CCA is its highly desmoplastic microenvironment containing fibrogenic connective tissue and an abundance of immune cells (T lymphocytes, Natural Killer (NK) cells, and macrophages) infiltrating tumor epithelium. This strong desmoplasia is orchestrated by various soluble factors and signals, suggesting a critical role in shaping a tumor growth-permissive microenvironment that is responsible for CCA poor clinical outcome. Indeed stroma not only provides an abundance of factors that facilitate CCA initiation, growth and progression, but also a prejudicial impact on therapeutic outcome. This review will give an overview of tumor-stroma signaling in a microenvironment critically regulating CCA development and progression. Identification of CCA secreted factors by both the fibroblast component and immune cell subsets might provide ample opportunities for pharmacological targeting of this type of cancer.

MiR-124 induces autophagy-related cell death in cholangiocarcinoma cells through direct targeting of the EZH2-STAT3 signaling axis

Cholangiocarcinoma (CCA) is a lethal cancer associated with chronic inflammation that has increased in prevalence in recent decades. The dysregulated expression of microRNAs (miRNAs) has been detected in various types of malignancies, and depending on the target genes this can result in miRNAs functioning as tumor suppressors or oncogenes. In this study, we investigated the role of miR-124 in cholangiocarcinoma (CCA) and found that its expression was significantly downregulated in the tumor tissue of patients and in CCA cell lines. Our results provided evidence that miR-124 induces apoptotic cell death and triggers the autophagic flux in CCA cells. EZH2 and STAT3 were identified as direct targets of miR-124. The effect of miR-124 on EZH2 expression in CCA cells was evaluated using cell transfection, xenotransplantation into nude mice and a luciferase reporter assay. Silencing of EZH2 restored the effects of miR-124, whereas overexpression of EZH2 abrogated the effects of miR-124. Silencing of Beclin1 or ATG5 abrogated the effects of miR-124 or siEZH2. In vivo, overexpression of miR-124 dramatically induced autophagy-related cell death and suppressed tumorigenicity. Taken together, our findings indicated that downregulation of miR-124 expression was associated with disease progression in human CCA and we revealed that miR-124 exerts a tumor suppressive function in CCA by inducing autophagy-related cell death via direct targeting of the EZH2-STAT3 signaling axis.

Clonorchis sinensis excretory-secretory products promote the migration and invasion of cholangiocarcinoma cells by activating the integrin β4-FAK/Src signaling pathway

Cholangiocarcinoma (CCA) is a slow-growing but highly metastatic cancer. Its metastatic potential largely explains its high mortality rate. A recognized risk factor for CCA development is infection with the liver flukes Opisthorchis viverrini and Clonorchis sinensis. We previously reported that the excretory-secretory products (ESPs) of C. sinensis promoted the three-dimensional aggregation and invasion of CCA cells. In the present study, a quantitative real-time PCR array of extracellular matrix (ECM) and adhesion molecules was used to examine the regulatory mechanism of ESP-mediated CCA cell migration and invasion. In particular, the expression levels of integrin α isoforms and β4 were upregulated in response to ESPs. Increased expression of integrin β4 was probably correlated with activation of focal adhesion kinase (FAK) and the steroid receptor coactivator (Src) family kinase and the subsequent activation of two downstream focal adhesion molecules, paxillin and vinculin. Moreover, inhibition of FAK/Src activation reduced paxillin and vinculin phosphorylation and attenuated ESP-induced CCA cell migration and invasion. These findings suggest that the integrin β4-FAK/Src signaling axis may play a crucial role in clonorchiasis-associated CCA metastasis during tumor progression.

Intrahepatic cholangiocarcinoma: current perspectives

Intrahepatic cholangiocarcinoma (ICC) is the second most common malignancy arising from the liver. ICC makes up about 10% of all cholangiocarcinomas. It arises from the peripheral bile ducts within the liver parenchyma, proximal to the secondary biliary radicals. Histologically, the majority of ICCs are adenocarcinomas. Only a minority of patients (15%) present with resectable disease, with a median survival of less than 3 years. Multidisciplinary management of ICC is complicated by large differences in disease course for individual patients both across and within tumor stages. Risk models and nomograms have been developed to more accurately predict survival of individual patients based on clinical parameters. Predictive risk factors are necessary to improve patient selection for systemic treatments. Molecular differences between tumors, such as in the epidermal growth factor receptor status, are promising, but their clinical applicability should be validated. For patients with locally advanced disease, several treatment strategies are being evaluated. Both hepatic arterial infusion chemotherapy with floxuridine and yttrium-90 embolization aim to downstage locally advanced ICC. Selected patients have resectable disease after downstaging, and other patients might benefit because of postponing widespread dissemination and biliary obstruction.

Clonorchis sinensis, an oriental liver fluke, as a human biological agent of cholangiocarcinoma: a brief review

Parasitic diseases remain an unarguable public health problem worldwide. Liver fluke Clonorchis sinensis is a high risk pathogenic parasitic helminth which is endemic predominantly in Asian countries, including Korea, China, Taiwan, Vietnam, and the far eastern parts of Russia, and is still actively transmitted. According to the earlier 8^th National Survey on the Prevalence of Intestinal Parasitic Infections in 2012, C. sinensis was revealed as the parasite with highest prevalence of 1.86% in general population among all parasite species surveyed in Korea. This fluke is now classified under one of the definite Group 1 human biological agents (carcinogens) by International Agency of Research on Cancer (IARC) along with two other parasites, Opisthorchis viverrini and Schistosoma haematobium. C. sinensis infestation is mainly linked to liver and biliary disorders, especially cholangiocarcinoma (CCA). For the purposes of this mini-review, we will only focus on C. sinensis and review pathogenesis and carcinogenesis of clonorchiasis, disease condition by C. sinensis infestation, and association between C. sinensis infestation and CCA. In this presentation, we briefly consider the current scientific status for progression of CCA by heavy C. sinensis infestation from the food-borne trematode and development of CCA.

LncRNAs H19 and HULC, activated by oxidative stress, promote cell migration and invasion in cholangiocarcinoma through a ceRNA manner

Background

Long non-coding RNAs (lncRNAs) are known to play important roles in different cell contexts, including cancers. However, little is known about lncRNAs in cholangiocarcinoma (CCA), a cholangiocyte malignancy with poor prognosis, associated with chronic inflammation and damage to the biliary epithelium. The aim of the study is to identify if any lncRNA might associate with inflammation or oxidative stress in CCA and regulate the disease progression.

Methods

In this study, RNA-seqs datasets were used to identify aberrantly expressed lncRNAs. Small interfering RNA and overexpressed plasmids were used to modulate the expression of lncRNAs, and luciferase target assay RNA immunoprecipitation (RIP) was performed to explore the mechanism of miRNA-lncRNA sponging.

Results

We firstly analyzed five available RNA-seqs datasets to investigate aberrantly expressed lncRNAs which might associate with inflammation or oxidative stress. We identified that two lncRNAs, H19 and HULC, were differentially expressed among all the samples under the treatment of hypoxic or inflammatory factors, and they were shown to be stimulated by short-term oxidative stress responses to H₂O₂ and glucose oxidase in CCA cell lines. Further studies revealed that these two lncRNAs promoted cholangiocyte migration and invasion via the inflammation pathway. H19 and HULC functioned as competing endogenous RNAs (ceRNAs) by sponging let-7a/let-7b and miR-372/miR-373, respectively, which activate pivotal inflammation cytokine IL-6 and chemokine receptor CXCR4.

Conclusions

Our study revealed that H19 and HULC, up-regulated by oxidative stress, regulate CCA cell migration and invasion by targeting IL-6 and CXCR4 via ceRNA patterns of sponging let-7a/let-7b and miR-372/miR-373, respectively. The results suggest that these lncRNAs might be the chief culprits of CCA pathogenesis and progression. The study provides new insight into the mechanism linking lncRNA function with CCA and may serve as novel targets for the development of new countermeasures of CCA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0348-0) contains supplementary material, which is available to authorized users.

miR-17-92 cluster promotes cholangiocarcinoma growth: evidence for PTEN as downstream target and IL-6/Stat3 as upstream activator

miR-17-92 is an oncogenic miRNA cluster implicated in the development of several cancers; however, it remains unknown whether the miR-17-92 cluster is able to regulate cholangiocarcinogenesis. This study was designed to investigate the biological functions and molecular mechanisms of the miR-17-92 cluster in cholangiocarcinoma. In situ hybridization and quantitative RT-PCR analysis showed that the miR-17-92 cluster is highly expressed in human cholangiocarcinoma cells compared with the nonneoplastic biliary epithelial cells. Forced overexpression of the miR-17-92 cluster or its members, miR-92a and miR-19a, in cultured human cholangiocarcinoma cells enhanced tumor cell proliferation, colony formation, and invasiveness, in vitro. Overexpression of the miR-17-92 cluster or miR-92a also enhanced cholangiocarcinoma growth in vivo in hairless outbred mice with severe combined immunodeficiency (SHO-Prkdc(scid)Hr(hr)). The tumor-suppressor, phosphatase and tensin homolog deleted on chromosome 10 (PTEN), was identified as a bona fide target of both miR-92a and miR-19a in cholangiocarcinoma cells via sequence prediction, 3' untranslated region luciferase activity assay, and Western blot analysis. Accordingly, overexpression of the PTEN open reading frame protein (devoid of 3' untranslated region) prevented miR-92a- or miR-19a-induced cholangiocarcinoma cell growth. Microarray analysis revealed additional targets of the miR-17-92 cluster in human cholangiocarcinoma cells, including APAF-1 and PRDM2. Moreover, we observed that the expression of the miR-17-92 cluster is regulated by IL-6/Stat3, a key oncogenic signaling pathway pivotal in cholangiocarcinogenesis. Taken together, our findings disclose a novel IL-6/Stat3-miR-17-92 cluster-PTEN signaling axis that is crucial for cholangiocarcinogenesis and tumor progression.

Sox9 expression in carcinogenesis and its clinical significance in intrahepatic cholangiocarcinoma

BACKGROUND

Intrahepatic cholangiocarcinomas develop through a multi-step carcinogenesis. Precancerous lesions are defined as biliary intraepithelial neoplasia. Sex determining region Y-box9 (Sox9) is required for the normal differentiation of the biliary tract.

AIMS

To evaluate the Sox9 expression in carcinogenesis and its correlation with clinicopathological features in intrahepatic cholangiocarcinoma.

METHODS

Sox9 expression in normal epithelium, biliary intraepithelial neoplasia, and intrahepatic cholangiocarcinoma were investigated immunohistochemically using 43 specimens of intrahepatic cholangiocarcinoma. Sox9 expression in intrahepatic cholangiocarcinoma was compared with the clinicopathological features. The molecular effects of Sox9 were investigated by gene transfection to intrahepatic cholangiocarcinoma cell lines.

RESULTS

Sox9 expression was decreased from the normal epithelium to the biliary intraepithelial neoplasia in a stepwise fashion. In 51.2% (22/43) of the patients with intrahepatic cholangiocarcinoma, Sox9 expression was positive, and Sox9 expression was significantly associated with the biliary infiltration (P=0.034) and poor overall survival (P=0.039). Upregulation of Sox9 promoted the cell migration and invasion, and decreased the E-cadherin expression and increased the vimentin and α-SMA expression in cell lines.

CONCLUSIONS

Decreased Sox9 expression may be related to the early stage of the carcinogenesis of intrahepatic cholangiocarcinoma. Sox9 overexpression in intrahepatic cholangiocarcinoma is related to biliary infiltration and poorer prognosis, and it promotes cell migration and invasion, via the epithelial-to-mesenchymal transition.

Synergistic anticancer effects of cisplatin and histone deacetylase inhibitors (SAHA and TSA) on cholangiocarcinoma cell lines

Clinical application of cisplatin against cholangiocarcinoma is often associated with resistance and toxicity posing urgent demand for combination therapy. In this study, we evaluated the combined anticancer effect of cisplatin and histone deacetylase inhibitors (HDACIs), suberoylanilide hydroxamic acid (SAHA) and trichostatin A (TSA), on the cholangiocarcinoma KKU-100 and KKU-M214 cell lines. Antiproliferative activity was evaluated using MTT assay. Apoptosis induction and cell cycle arrest were analyzed by flow cytometry. Cell cycle and apoptosis regulating proteins were evaluated by western blot analysis. MTT assay showed that cisplatin, SAHA and TSA dose-dependently reduced the viability of KKU-100 and KKU-M214 cells. The combination of cisplatin and HDACIs exerted significantly more cytotoxicity than the single drugs. Combination indices below 1.0 reflect synergism between cisplatin and HDACIs, leading to positive dose reductions of cisplatin and HDACIs. Cisplatin and HDACIs alone induced G0/G1 phase arrest in KKU-100 cells, but the drug combinations increased sub-G1 percent more than either drug. However, cisplatin and HDACIs alone or in combination increased only the sub-G1 percent in KKU-M214 cells. Annexin V-FITC staining revealed that cisplatin and HDACIs combinations induced more apoptotic cell death of both KKU-100 and KKU-M214 cells than the single drug. In KKU-100 cells, growth inhibition was accompanied by upregulation of p53 and p21 and downregulation of CDK4 and Bcl-2 due to exposure to cisplatin, SAHA and TSA alone or in combination. Moreover, combination of agents exerted higher impacts on protein expression. Single agents or combination did not affect p53 expression, however, combination of cisplatin and HDACIs increased the expression of p21 in KKU-M214 cells. Taken together, cisplatin and HDACIs combination may improve the therapeutic outcome in cholangiocarcinoma patients.

Genome-wide screen identified let-7c/miR-99a/miR-125b regulating tumor progression and stem-like properties in cholangiocarcinoma

Cholangiocarcinoma (CCA), which is a poor prognosis malignancy that arises from the malignant transformation of cholangiocytes, is associated with chronic inflammation of the biliary epithelium. Thus far, the molecular mechanisms of the origin and neoplastic processes of CCA that are promoted by inflammation are still unclear and need to be fully elucidated. Here using small RNA sequencing to determine the microRNA (miRNA) expression profiles in CCA, we found that let-7c, miR-99a and miR-125b, which are three miRNAs of the same cluster, were downregulated in CCA and targeted interleukin 6 (IL-6), IL-6R and type 1 insulin-like growth factor, which are important cytokines and receptors of the IL-6/signal transducer and activator 3 (STAT3) pathway and have key roles in inflammation and CCA initiation. We also found that enforced expression of let-7c, miR-99a or miR-125b could reduce the activity of STAT3 and further suppress CCA tumorigenicity in vivo and inhibit the migration and invasion of CCA cells in vitro. Surprisingly, let-7c/miR-99a/miR-125b cluster also significantly decreased the ability of CCA cells for cancer stem cell-like mammosphere generation by downregulating CD133 and CD44, which suggests the pivotal roles of let-7c, miR-99a and miR-125b in CCA by regulating both inflammation and stem-like properties. Our findings showed potential links between miRNAs and inflammation, and provide a potential treatment strategy for developing an miRNA-based therapy via IL-6/STAT3 targeting for CCA.

The Role of Endoscopy in the Diagnosis and Management of Cholangiocarcinoma

Cholangiocarcinomas (CCAs) are associated with poor overall survival, and majority of the tumors are unresectable at the time of diagnosis. Early diagnosis at a resectable stage is essential for improved outcomes. Noninvasive imaging plays an important role in evaluating patients with biliary obstruction, but is limited due to the lack of tissue sampling and in many cases due to the absence of a mass, especially for extrahepatic CCAs. Endoscopic diagnosis is needed in majority of patients with CCA and the diagnostic yield depends on the tumor location as well as the expertise and experience of the endoscopist. Endoscopic retrograde cholangiopancreatography and endoscopic ultrasound remain the most common endoscopic diagnostic tools although newer technologies including fluorescence in situ hybridization, single-operator cholangioscopy, confocal laser endomicroscopy, and intraductal ultrasound are being increasing used. Traditionally, the role of endoscopy has been mainly palliative and limited to biliary drainage in patients with obstructive jaundice, however, newer treatment options like photodynamic therapy and radiofrequency ablation have shown promise toward improved patient survival. Multidisciplinary approach that involves medical oncology, gastroenterology, radiology, and surgical oncology teams is imperative for improved outcomes. In this review, we will first review the diagnostic approach to CCAs including imaging and endoscopic methods followed by a discussion of different endoscopic techniques in management of patients after a diagnosis of CCA.

Cholangiocarcinoma: from molecular biology to treatment

Cholangiocarcinoma is a rare tumor originating in the bile ducts, which, according to their anatomical location, is classified as intrahepatic, extrahepatic and hilar. Nevertheless, incidence rates have increased markedly in recent decades. With respect to tumor biology, several genetic alterations correlated with resistance to chemotherapy and radiotherapy have been identified. Here, we highlight changes in KRAS and TP53 genes that are normally associated with a more aggressive phenotype. Also IL-6 and some proteins of the BCL-2 family appear to be involved in the resistance that the cholangiocarcinoma presents toward conventional therapies. With regard to diagnosis, tumor markers most commonly used are CEA and CA 19-9, and although its use isolated appears controversial, their combined value has been increasingly advocated. In imaging terms, various methods are needed, such as abdominal ultrasound, computed tomography and cholangiopancreatography. Regarding therapy, surgical modalities are the only ones that offer chance of cure; however, due to late diagnosis, most patients cannot take advantage of them. Thus, the majority of patients are directed to other therapeutic modalities like chemotherapy, which, in this context, assumes a purely palliative role. Thus, it becomes urgent to investigate new therapeutic options for this highly aggressive type of tumor.

Defensive mechanism in cholangiocarcinoma cells against oxidative stress induced by chlorin e6-based photodynamic therapy

In this study, the effect of chlorin e6-based photodynamic therapy (Ce6-PDT) was investigated in human intrahepatic (HuCC-T1) and extrahepatic (SNU1196) cholangiocarcinoma (CCA) cells. The amount of intracellular Ce6 increased with increasing Ce6 concentration administered, or with incubation time, in both cell lines. The ability to take up Ce6 and generate reactive oxygen species after irradiation at 1.0 J/cm² did not significantly differ between the two CCA cell types. However, after irradiation, marked differences were observed for photodamage and apoptotic/necrotic signals. HuCC-T1 cells are more sensitive to Ce6-PDT than SNU1196 cells. Total glutathione (GSH) levels, glutathione peroxidase and glutathione reductase activities in SNU1196 cells were significantly higher than in HuCC-T1 cells. With inhibition of enzyme activity or addition of GSH, the phototoxic effect could be controlled in CCA cells. The intracellular level of GSH is the most important determining factor in the curative action of Ce6-PDT against tumor cells.

miR-101 inhibits cholangiocarcinoma angiogenesis through targeting vascular endothelial growth factor (VEGF)

Recent evidence has suggested an important role of miRNAs in liver biology and diseases, although the implication of miRNAs in cholangiocarcinoma remains to be defined further. This study was designed to examine the biological function and molecular mechanism of miR-101 in cholangiocarcinogenesis and tumor progression. In situ hybridization and quantitative RT-PCR were performed to determine the expression of miR-101 in human cholangiocarcinoma tissues and cell lines. Compared with noncancerous biliary epithelial cells, the expression of miR-101 is decreased in 43.5% of human cholangiocarcinoma specimens and in all three cholangiocarcinoma cell lines used in this study. Forced overexpression of miR-101 significantly inhibited cholangiocarcinoma growth in severe combined immunodeficiency mice. miR-101-overexpressed xenograft tumor tissues showed decreased capillary densities and decreased levels of vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2). The VEGF and COX-2 mRNAs were identified as the bona fide targets of miR-101 in cholangiocarcinoma cells by both computational analysis and experimental assays. miR-101 inhibits cholangiocarcinoma angiogenesis by direct targeting of VEGF mRNA 3'untranslated region and by repression of VEGF gene transcription through inhibition of COX-2. This study established a novel tumor-suppressor role of miR-101 in cholangiocarcinoma and it suggests the possibility of targeting miR-101 and related signaling pathways for future therapy.

Cholangiocarcinoma: treatment with sorafenib extended life expectancy to greater than four years

INTRODUCTION

Cholangiocarcinomas arise from the epithelial cells of intrahepatic and extrahepatic bile ducts. They generally have a very poor prognosis. Many studies report a dismal median survival of approximately 6 months. In this case, we have a patient diagnosed with cholangiocarcinoma who has remarkably exceeded life expectancy to greater than 4 years with a fourth line agent Sorafenib.

CASE DESCRIPTION

This is a 51 y/o male who was diagnosed with cholangiocarcinoma approximately 
4.5 years ago. After initial work up suggested locally advanced carcinoma, the patient was started on systemic chemotherapy. Despite multiple cycles with GEMOX, capecitabine and 5-FU, the carcinoma progressed. A fourth line agent, Sorafenib, was initiated. This multikinase inhibitor drug is FDA approved for hepatocellular carcinoma and renal cell carcinoma, however the potential efficacy of this agent for treating cholangiocarcinoma is largely unknown. Despite some latest trials suggesting a median survival of 
4.4 months, our patient has survived on this chemotherapy agent for almost 4 years now.

DISCUSSION

This case illustrates the potential benefit of using Sorafenib in locally advanced cholangiocarcinoma. This provides hope for more trials, to establish selection criteria for administration of this drug.

New and emerging treatment options for biliary tract cancer

Biliary tract cancer (BTC) is a group of relatively rare tumors with a poor prognosis. The current standard of care consists of doublet chemotherapy (platinum plus gemcitabine); however, even with cytotoxic therapy, the median overall survival is less than 1 year. The genetic basis of BTC is now more clearly understood, allowing for the investigation of targeted therapy. Combinations of doublet chemotherapy with antiepidermal growth factor receptor agents have provided modest results in Phase II and Phase III setting, and responses with small molecule inhibitors are limited. Moving forward as we continue to characterize the genetic hallmarks of BTC, a stepwise, strategic, and cooperative approach will allow us to make progress when developing new treatments.

Ursodeoxycholic acid-conjugated chitosan for photodynamic treatment of HuCC-T1 human cholangiocarcinoma cells

Chitosan was hydrophobically modified with ursodeoxycholic acid (UDCA) to fabricate nano-photosensitizer for photodynamic therapy (PDT) of HuCC-T1 cholangiocarcinoma cells. Synthesis of UDCA-conjugated chitosan (ChitoUDCA) was confirmed using (1)H NMR spectra. Chlorin E6 (Ce6) was used as a photosensitizer and incorporated into ChitoUDCA nanoparticles through formation of ion complexes. Morphology of Ce6-incorporated ChitoUDCA nanoparticles was observed using TEM and their shapes were spherical with sizes around 200-400 nm. The PDT potential of Ce6-incorporated ChitoUDCA nanoparticles were studied with HuCC-T1 human cholangiocarcinoma cells. The results showed that ChitoUDCA nanoparticles enhances of Ce6 uptake into tumor cells, phototoxicity, and ROS generation compared to Ce6 itself. Furthermore, Ce6-incorporated ChitoUDCA nanoparticles showed quenching in aqueous solution and sensing at tumor cells. We suggest that Ce6-incorporated ChitoUDCA nanoparticles are promising candidates for PDT of cholangiocarcinoma cells.

Resection for hilar cholangiocarcinoma: analysis of prognostic factors and the impact of systemic inflammation on long-term outcome

INTRODUCTION

Resection for hilar cholangiocarcinoma is the single hope for long-term survival.

METHODS

Ninety patients underwent curative intent surgery for hilar cholangiocarcinoma between 1996 and 2012. The potential prognostic factors were assessed by univariate (Kaplan-Meier curves and log-rank test) and multivariate analyses (Cox proportional hazards model).

RESULTS

The median overall and disease-free survivals were 26 and 17 months, respectively. The multivariate analysis identified R0 resection (HR = 0.03, 95 % CI 0-0.19, p < 0.001), caudate lobe invasion (HR = 6.33, 95 % CI 1.31-30.46, p = 0.021), adjuvant gemcitabine-based chemotherapy (HR = 0.38, 95 % CI 0.15-0.94, p = 0.037), and the neutrophil-to-lymphocyte ratio (HR = 0.78, 95 % CI 0.62-0.98, p = 0.036) as independent prognostic factors for disease-free survival. The independent prognostic factors for overall survival were R0 resection (HR = 0.03, 95 % CI 0-0.22, p < 0.001), caudate lobe invasion (HR = 11.75, 95 % CI 1.65-83.33, p = 0.014), and adjuvant gemcitabine-based chemotherapy (HR = 0.19, 95 % CI 0.06-0.56, p = 0.003).

CONCLUSIONS

The negative resection margin represents the most important prognostic factor. Adjuvant gemcitabine-based chemotherapy appears to benefit survival. The neutrophil-to-lymphocyte ratio may potentially be used to stratify patients for future clinical trials.

Primary sclerosing cholangitis: a review and update on therapeutic developments

Primary sclerosing cholangitis (PSC) is a chronic, cholestatic, idiopathic liver disease characterized by fibro-obliterative inflammation of the hepatic bile ducts. In a clinically significant proportion of patients, PSC progresses to cirrhosis, end-stage liver disease, and in some cases, cholangiocarcinoma. Despite clinical trials of nearly 20 different pharmacotherapies over several decades, safe and effective medical therapy, albeit critically needed, remains to be established. PSC is pathogenically complex, with genetic, immune, enteric microbial, environmental and other factors being potentially involved and, thus, not surprisingly, it manifests as a clinically heterogeneous disease with a relatively unpredictable course. It is likely that this complexity and clinical heterogeneity are responsible for the negative results of clinical trials, but novel insights about and approaches to PSC may shift this trend. The authors herein provide a review of previously tested pharmacologic agents, discuss emerging fundamental concepts and present viewpoints regarding how identifying therapies for PSC may evolve over the next several years.

Obesity and cholangiocarcinoma

It is estimated that about half of the population in developed countries are either overweight or obese. In some developing nations obesity rates have increased to surpass those seen in Western countries. This rate increase in obesity has many implications as obesity has been associated with numerous negative health effects including increased risks of hypertension, diabetes, cardiovascular disease, stroke, liver disease, apnea, and some cancer types. Obesity is now considered to be one of the major public health concerns facing the society. Cholangiocarcinomas (bile duct cancers) are malignant tumors arising from cholangiocytes inside or outside of the liver. Although cholangiocarcinomas are relatively rare, they are highly lethal. The low survival rate associated with cholangiocarcinoma is due to the advanced stage of the disease at the time of diagnosis. Prevention is therefore especially important in this cancer type. Some data suggest that the incidence of cholangiocarcinoma in the western world is on the rise. Increasing rate of obesity may be one of the factors responsible for this increase. Determining whether obesity is a risk factor for cholangiocarcinoma has significant clinical and societal implications as obesity is both prevalent and modifiable. This paper seeks to provide a summary of the current knowledge linking obesity and cholangiocarcinoma, and encourage further research on this topic.

Adenoma-carcinoma sequence in intrahepatic cholangiocarcinoma

INTRODUCTION

Cholangiocarcinoma is a rare tumor but recent data report a worldwide increase in incidence and mortality. There are several risk factors associated with cholangiocarcinoma, and chronic inflammation of billiary tree seems to be implied in the cholangiocarcinogenesis, but little is known about this process.

PRESENTATION OF CASE

We present a 56-year-old female with a bile duct adenoma incidentally discovered in the follow up of breast cancer that 18 months later progress to intrahepatic cholangiocarcinoma.

DISCUSSION

This is a rare presentation of intrahepatic cholangiocarcinoma that suggests the classic adenoma-carcinoma sequence in cholangiocarcinogenesis. Furthermore this case gives rise to some questions about the possible common ground on intrahepatic cholangiocarcinoma and breast cancer.

CONCLUSION

Cholangiocarcinogenesis is a complex multi-step mechanism and further investigations are needed to fully understand this process.