Drug sensitivity and drug resistance profiles of human intrahepatic cholangiocarcinoma cell lines

Biological and genetic characterization of a newly established human primary multidrug-resistant distal cholangiocarcinoma cell line, CBC3T-6

Distal cholangiocarcinoma is a rare and highly aggressive malignant tumor. The inherent tumor characteristics and growth pattern of cancer cells pose a challenge for diagnosis and treatment. Chemotherapy resistance leads to limited treatment options for patients with advanced cholangiocarcinoma. However, drug resistance studies in cholangiocarcinoma are often limited by the use of preclinical models that do not accurately replicate the essential features of the disease. In this study, we established and characterized a primary multidrug-resistant distal cholangiocarcinoma cell line, CBC3T-6. STR profiling indicated no evidence of cross-contamination. This cell line remains stable during long-term in vitro culture and is characterized by short doubling times and rapid subcutaneous tumor formation in mice. In addition, among the first-line anticancer drugs for cholangiocarcinoma, CBC3T-6 cells showed varying degrees of resistance to gemcitabine, oxaliplatin, cisplatin, and 5-FU. Whole exome sequencing analysis revealed that CBC3T-6 cells contained a variety of potentially pathogenic somatic cell mutations, such as TP53 and KRAS mutations. ABCB1 mutation as a possible therapeutic target for multidrug resistance. In conclusion, CBC3T-6 cells can be used as a useful tool to study the mechanism of cholangiocarcinoma and develop new therapeutic strategies for multidrug resistance.

Sensitizing cholangiocarcinoma to chemotherapy by inhibition of the drug-export pump MRP3

AIMS

Drug export through ABC proteins hinders cancer response to chemotherapy. Here, we have evaluated the relevance of MRP3 (ABCC3) in cholangiocarcinoma (CCA) as a potential target to overcome drug resistance.

METHODS

Gene expression was analyzed in silico using the TCGA-CHOL database and experimentally (mRNA and protein) in resected CCA tumors. The effect of manipulating MRP3 function/expression was evaluated in vitro and in vivo.

RESULTS

High MRP3 expression at the plasma membrane of human CCA cells was found. MRP3 overexpression in HEK293T cells selectively impaired the cytotoxic effect of etoposide, cisplatin, SN-38, and mitoxantrone. Reduced MRP3 activity with shRNAs or pan-MRP blockers enhanced the sensitivity to these drugs. MRP3 interaction with natural and semisynthetic compounds (≈40,000) was evaluated by virtual drug screening and molecular docking. Two identified potential MRP3 inhibitors (EM-114, EM-188), and sorafenib impaired MRP3 transport activity and enhanced sensitivity of CCA cells to etoposide and cisplatin. The antitumor effect of cisplatin in the mouse xenograft model was enhanced by co-treatment with sorafenib, which was accompanied by a higher intratumor accumulation of cisplatin.

CONCLUSIONS

Genetic and pharmacological MRP3 inhibition enhances the anti-CCA effect of several drugs, which constitutes a promising strategy to improve the response to chemotherapy in CCA patients.

Analysis of the Effector Functions of Vδ2 γδ T Cells and NK Cells against Cholangiocarcinoma Cells

Cholangiocarcinoma (CCA) is a rare disease characterized by malignant cells derived from the epithelial cells of the biliary duct system. Despite extensive treatments, the prognosis for CCA remains poor, emphasizing the critical need for the development of novel treatments. Considerable attention has been directed towards innate immune effector cells, which can recognize tumor cells independently of the major histocompatibility complex, laying the foundation for the development of off-the-shelf drugs. In this study, we cultured innate immune cells obtained from the peripheral blood of healthy adults and conducted a comparative analysis of the effector functions against CCA cell lines by Vδ2 γδ T cells and NK cells. This analysis was performed using standard short- and long-term cytotoxicity assays, as well as ELISA for IFN-γ. Vδ2 γδ T cells demonstrated cytotoxicity and IFN-γ production in response to CCA cells in a TCR-dependent manner, particularly in the presence of tetrakis-pivaloyloxymethyl 2-(thiazole-2-ylamino)ethylidene-1,1-bisphosphonate, a bisphosphonate prodrug. In contrast, direct killing and antibody-dependent cellular cytotoxicity were relatively slow and weak. Conversely, NK cells displayed potent, direct cytotoxicity against CCA cells. In summary, both Vδ2 γδ T cells and NK cells show promise as innate immune effector cells for adoptive transfer therapy in the context of CCA.

Precision immunotherapy for cholangiocarcinoma: Pioneering the use of human-derived anti-cMET single chain variable fragment in anti-cMET chimeric antigen receptor (CAR) NK cells

Cholangiocarcinoma (CCA) presents a significant clinical challenge which is often identified in advanced stages, therby restricting the effectiveness of surgical interventions for most patients. The high incidence of cancer recurrence and resistance to chemotherapy further contribute to a bleak prognosis and low survival rates. To address this pressing need for effective therapeutic strategies, our study focuses on the development of an innovative cellular immunotherapy, specifically utilizing chimeric antigen receptor (CAR)-engineered natural killer (NK) cells designed to target the cMET receptor tyrosine kinase. In this investigation, we initiated the screening of a phage library displaying human single-chain variable fragment (ScFv) to identify novel ScFv molecules with specificity for cMET. Remarkably, ScFv11, ScFv72, and ScFv114 demonstrated exceptional binding affinity, confirmed by molecular docking analysis. These selected ScFvs, in addition to the well-established anti-cMET ScFvA, were integrated into a CAR cassette harboring CD28 transmembrane region-41BB-CD3ζ domains. The resulting anti-cMET CAR constructs were transduced into NK-92 cells, generating potent anti-cMET CAR-NK-92 cells. To assess the specificity and efficacy of these engineered cells, we employed KKU213A cells with high cMET expression and KKU055 cells with low cMET levels. Notably, co-culture of anti-cMET CAR-NK-92 cells with KKU213A cells resulted in significantly increased cell death, whereas no such effect was observed with KKU055 cells. In summary, our study identified cMET as a promising therapeutic target for CCA. The NK-92 cells, armed with the anti-cMET CAR molecule, have shown strong ability to kill cancer cells specifically, indicating their potential as a promising treatment for CCA in the future.

PLK1 inhibition leads to mitotic arrest and triggers apoptosis in cholangiocarcinoma cells

Cholangiocarcinoma (CCA) is a lethal cancer originating from the epithelial cells within the bile duct and ranks as the second most prevalent form of liver cancer in Thailand. Polo-like kinase 1 (PLK1), a protein serine/threonine kinase, regulates a number of steps in cell mitosis and is upregulated in several types of cancer, including CCA. Our previous study identified PLK1 as a biomarker of the C1 subtype, correlating with poor prognosis in intrahepatic CCA. The present study aimed to examine the effect of PLK1 inhibition on CCA cells. Different CCA cell lines developed from Thai patients, HuCCA1, KKU055, KKU100 and KKU213A, were treated with two PLK1 inhibitors, BI2536 and BI6727, and were transfected with small interfering RNA, followed by analysis of cell proliferation, cell cycle distribution and cell apoptosis. It was discovered that BI2536 and BI6727 inhibited cell proliferation and caused G2/M-phase arrest in CCA cells. Furthermore, the number of total apoptotic cells was increased in PLK1 inhibitor-treated CCA cells. The expression levels of mitotic proteins, aurora kinase A, phosphorylated PLK1 (T210) and cyclin B1, were augmented in PLK1-inhibited CCA cells. Additionally, inhibition of PLK1 led to increased DNA damage, as determined by the upregulated levels of γH2AX and increased cleavage of poly (ADP-ribose) polymerase, an apoptotic marker. These results suggested that inhibiting PLK1 prolonged mitotic arrest and subsequently triggered cell apoptosis. Validation of the antiproliferative effects of PLK1 inhibition was accomplished through silencing of the PLK1 gene. In conclusion, targeting PLK1 provided promising results for further study as a potential candidate for targeted therapy in CCA.

Microalga Chlorella sp. extract induced apoptotic cell death of cholangiocarcinoma via AKT/mTOR signaling pathway

Cancer is the leading cause of death worldwide. Drug resistance and relapse after current standard treatments frequently occur; thus, alternative and effective treatments are required. Algae and cyanobacteria are abundant organisms that serve as bioresources of nutrients/metabolites, which are attractive sources of numerous bioactive compounds for drug discovery. In the present study, we, therefore, investigated anti-cancer activities of crude polysaccharide and ethanolic extracts from Chlorella sp., Sargassum spp., and Spirulina sp. against cell lines of five top-leading cancers including lung cancer (A549), cervical cancer (Hela), breast cancer (MCF7), hepatocellular carcinoma (Huh7), and cholangiocarcinoma (CCA; KKU213A). Only ethanolic extracts of Chlorella sp. showed consistent inhibition of growth of all cancer cell types. CCA was the most sensitive to Chlorella sp. ethanolic extract with CC50 of 277.4, 400.5, and 313.4 µg/mL for KKU055, KKU100, and KKU213A cells, respectively. Flow cytometric analysis demonstrated that CCA cell death was triggered via apoptosis pathway in accompany with lowering procaspase-3, -8, and -9 and increasing caspase enzymatic activity in addition to reducing anti-apoptosis Bcl-2 protein. Interestingly, the treatment of the extract at 400 µg/mL greatly inhibited the AKT/mTOR survival signaling as evidenced by significant reduction of phosphorylated-AKT and phosphorylated-mTOR proteins. The presence of reported bioactive compounds, gallic acid, and lutein, were confirmed in Chlorella sp. extract by high-performance liquid chromatography. Gallic acid and lutein treatment caused a significant reduction of KKU055, KKU100, and KKU213A cell viability. This study demonstrated the anti-cancer effect of Chlorella sp. ethanolic extract to promote cancer cell death via inhibition of AKT/mTOR pathway.

Development and Characterization of Human Primary Cholangiocarcinoma Cell Lines

Cholangiocarcinoma (CCA) is the second most common primary liver tumor and is associated with late diagnosis, limited treatment options, and a 5-year survival rate of around 30%. CCA cell lines were first established in 1971, and since then, only 70 to 80 CCA cell lines have been established. These cell lines have been essential in basic and translational research to understand and identify novel mechanistic pathways, biomarkers, and disease-specific genes. Each CCA cell line has unique characteristics, reflecting a specific genotype, sex-related properties, and patient-related signatures, making them scientifically and commercially valuable. CCA cell lines are crucial in the use of novel technologies, such as three-dimensional organoid models, which help to model the tumor microenvironment and cell-to-cell crosstalk between tumor-neighboring cells. This review highlights crucial information on CCA cell lines, including: i) type of CCA (eg, intra- or extrahepatic), ii) isolation source (eg, primary tumor or xenograft), iii) chemical digestion method (eg, trypsin or collagenase), iv) cell-sorting method (colony isolation or removal of fibroblasts), v) maintenance-medium choice (eg, RPMI or Dulbecco's modified Eagle's medium), vi) cell morphology (eg, spindle or polygonal shape), and vii) doubling time of cells.

Genistein Sensitizes Human Cholangiocarcinoma Cell Lines to Be Susceptible to Natural Killer Cells

Cholangiocarcinoma (CCA) is a lethal bile duct cancer, which has poor treatment outcomes due to its high resistance to chemotherapy and cancer recurrence. Activation of aberrant anti-apoptotic signaling pathway has been reported to be a mechanism of chemoresistance and immune escape of CCA. Therefore, reversal of anti-apoptotic signaling pathway represents a feasible approach to potentiate effective treatments, especially for CCA with high chemoresistance. In this study, we demonstrated the effects of genistein on reactivation of apoptosis cascade and increase the susceptibility of CCA cells to natural killer (NK-92) cells. Genistein at 50 and 100 µM significantly activated extrinsic apoptotic pathway in CCA cells (KKU055, KKU100, and KKU213A), which was evident by reduction of procaspase-8 and -3 expression. Pretreatment of CCA cells with genistein at 50 µM, but not NK-92 cells, significantly increased NK-92 cell killing ability over the untreated control, suggesting the ability of genistein to sensitize CCA cells. Interestingly, genistein treatment could greatly lower the expression of cFLIP, an anti-apoptotic protein involved in the immune escape pathway, in addition to upregulation of death receptors, Fas- and TRAIL-receptors, in CCA cells, which might be the underlying molecular mechanism of genistein to sensitize CCA to be susceptible to NK-92 cells. Taken together, this finding revealed the benefit of genistein as a sensitizer to enhance the efficiency of NK cell immunotherapy for CCA.

Expression of Chemoresistance-Associated ABC Proteins in Hepatobiliary, Pancreatic and Gastrointestinal Cancers

Simple Summary

One-third of the approximately 10 million deaths yearly caused by cancer worldwide are due to hepatobiliary, pancreatic, and gastrointestinal tumors. One primary reason for this high mortality is the lack of response of these cancers to pharmacological treatment. More than 100 genes have been identified as responsible for seven mechanisms of chemoresistance, but only a few of them play a critical role. These include ABC proteins (mainly MDR1, MRP1-6, and BCRP), whose expression pattern greatly determines the individual sensitivity of each tumor to pharmacotherapy.

Abstract

Hepatobiliary, pancreatic, and gastrointestinal cancers account for 36% of the ten million deaths caused by cancer worldwide every year. The two main reasons for this high mortality are their late diagnosis and their high refractoriness to pharmacological treatments, regardless of whether these are based on classical chemotherapeutic agents, targeted drugs, or newer immunomodulators. Mechanisms of chemoresistance (MOC) defining the multidrug resistance (MDR) phenotype of each tumor depend on the synergic function of proteins encoded by more than one hundred genes classified into seven groups (MOC1-7). Among them, the efflux of active agents from cancer cells across the plasma membrane caused by members of the superfamily of ATP-binding cassette (ABC) proteins (MOC-1b) plays a crucial role in determining tumor MDR. Although seven families of human ABC proteins are known, only a few pumps (mainly MDR1, MRP1-6, and BCRP) have been associated with reducing drug content and hence inducing chemoresistance in hepatobiliary, pancreatic, and gastrointestinal cancer cells. The present descriptive review, which compiles the updated information on the expression of these ABC proteins, will be helpful because there is still some confusion on the actual relevance of these pumps in response to pharmacological regimens currently used in treating these cancers. Moreover, we aim to define the MOC pattern on a tumor-by-tumor basis, even in a dynamic way, because it can vary during tumor progression and in response to chemotherapy. This information is indispensable for developing novel strategies for sensitization.

Overcome Drug Resistance in Cholangiocarcinoma: New Insight Into Mechanisms and Refining the Preclinical Experiment Models

Cholangiocarcinoma (CCA) is an aggressive tumor characterized by a poor prognosis. Therapeutic options are limited in patients with advanced stage of CCA, as a result of the intrinsic or acquired resistance to currently available chemotherapeutic agents, and the lack of new drugs entering into clinical application. The challenge in translating basic research to the clinical setting, caused by preclinical models not being able to recapitulate the tumor characteristics of the patient, seems to be an important reason for the lack of effective and specific therapies for CCA. So, there seems to be two ways to improve patient outcomes. The first one is developing the combination therapies based on a better understanding of the mechanisms contributing to the resistance to currently available chemotherapeutic agents. The second one is developing novel preclinical experimental models that better recapitulate the genetic and histopathological features of the primary tumor, facilitating the screening of new drugs for CCA patients. In this review, we discussed the evidence implicating the mechanisms underlying treatment resistance to currently investigated drugs, and the development of preclinical experiment models for CCA.

Chemoresistance and resistance to targeted therapies in biliary tract cancer: What have we learned?

INTRODUCTION

Biliary tract cancer (BTC), including intra- and extrahepatic cholangiocarcinoma and gallbladder cancer, is a rare and highly difficult to manage human malignancy. Besides late diagnosis and associated unresectability, frequently observed unresponsiveness towards and recurrence following chemotherapy or targeted therapy essentially contribute to the dismal prognosis of BTC patients.

AREAS COVERED

The review provides an update on individual mechanisms involved resistance of BTC towards conventional chemotherapy as well as targeted therapies. We review the distinct mechanisms of pharmacoresistance (MPRs) which have been defined in BTC cells on a molecular basis and examine the specific consequences for the various approaches of chemo-, targeted or immunomodulatory therapies.

EXPERT OPINION

Based on currently available experimental and clinical data, the present knowledge about these MPRs in BTCs are summarized. While some possible tactics for overcoming these mechanisms of resistance have been investigated, a BTC-specific and efficient approach based on comprehensive in vitro and in vivo experimental systems is not yet available. Additionally, a reliable monitoring of therapy-relevant cellular changes needs to be established which allows for choosing the optimal drug (combination) before and/or during pharmacological therapy.

FOXM1 inhibitor, Siomycin A, synergizes and restores 5-FU cytotoxicity in human cholangiocarcinoma cell lines via targeting thymidylate synthase

AIMS

5-Fluorouracil (5-FU), a thymidylate synthase (TS) inhibitor, has been used as the first-line chemotherapeutic drug for cholangiocarcinoma (CCA). The side effects and drug resistance have developed the limits of the clinical application of 5-FU in CCA treatment. Upregulation of Forkhead box M1 (FOXM1) and TS were shown to play a significant role in 5-FU resistance. In this study, the effect of Siomycin A (SioA), a FOXM1 inhibitor, on enhancing 5-FU cytotoxicity and reversing 5-FU resistance in CCA cell lines were demonstrated.

MAIN METHODS

Human CCA cell lines, KKU-100 and KKU-213A were used. Cell viability was determined using MTT assay. Expression of FOXM1 and TS proteins were determined using Western blotting. FOXM1 mRNA expression was quantitated using real-time PCR. The combination and dose reduction (DRI) were analyzed according to the Chou and Talalay method.

KEY FINDING

Single drug treatment of 5-FU and SioA effectively inhibited CCA cell growth in dose and time dependent fashions. The two CCA cell lines had different responses to 5-FU but exhibited similar sensitivity to SioA. FOXM1 and TS expression were increased in the 5-FU treated cells but were suppressed in the SioA treated cells. A direct binding of SioA, to TS and 5,10-methylene-tetrahydrofolate as an inactive ternary complex was simulated. The combined treatment of 5-FU with SioA showed a synergistic effect with a high DRI and restored 5-FU sensitivity in the 5-FU resistant cells.

SIGNIFICANCE

Targeting FOXM1 using SioA in combination with 5-FU might be a strategy to overcome the 5-FU resistance in CCA.

Anticancer effects of the combined Thai noni juice ethanolic extracts and 5-fluorouracil against cholangiocarcinoma cells in vitro and in vivo

Application of 5-fluorouracil (5-FU) in cholangiocarcinoma (CCA) is limited by adverse side effects and chemoresistance. Therefore, the combination therapy of 5-FU with other substances, especially natural products may provide a new strategy for CCA treatment. The aim of this study was to evaluate the combination effects of 5-FU and two ethanolic extracts of Thai noni juice (TNJ) products on CCA cell lines and nude mice xenografts. The results of antiproliferative assay showed the combination treatment of 5-FU and each TNJ ethanolic extract exerted more cytotoxicity on CCA cells than either single agent treatment. Synergistic effects of drug combinations can enable the dose reduction of 5-FU. The mechanism underlying a combination treatment was apoptosis induction through an activation of p53 and Bax proteins. In the nude mouse xenograft model, combination treatments of 5-FU with each TNJ ethanolic extract suppressed the growth of CCA cells implanted mice more than single agent treatments with no effects on mouse body weight, kidney, and spleen. Moreover, low doses of TNJ ethanolic extracts reduced the hepatotoxicity of 5-FU in nude mice. Taken together, these data suggested that the ethanolic extracts of TNJ products can enhance the anti-CCA effect and reduce toxicity of 5-FU.

Role of laminin and cognate receptors in cholangiocarcinoma cell migration

Extensive desmoplasia in cholangiocarcinoma (CCA) is associated with tumor aggressiveness, indicating a need for further understanding of CCA cell-matrix interaction. This study demonstrated laminin as the most potent attractant for CCA cell migration and the vast elevation of its receptor integrin β4 (ITGB4) in CCA cell lines. Besides, their high expressions in CCA tissues were correlated with lymphatic invasion and the presence of ITGB4 was also associated with short survival time. ITGB4 silencing revealed it as the receptor for laminin-induced HuCCA-1 migration, but KKU-213 utilized 37/67-kDa laminin receptor (LAMR) instead. These findings highlight the role of ITGB4 and LAMR in transducing laminin induction of CCA cell migration and the potential of ITGB4 as diagnostic and prognostic biomarkers for CCA.

Cholangiocarcinoma: bridging the translational gap from preclinical to clinical development and implications for future therapy

Introduction: Cholangiocarcinoma (CCA) is a devastating liver tumor with a poor prognosis. While less than 50% of the patients with CCA may benefit from surgical resection, the rest undergoes chemotherapy with disappointing results (mean survival <2 years). Alternative pharmacological treatments are needed to improve the outcomes in patients with CCA.Areas covered: In this review, we discuss CCA-related (1) experimental systems used in preclinical studies; (2) pharmacological targets identified by genetic analysis; (3) results obtained in preliminary trials in human with their pros and cons; and (4) possible targeting of endocrinal modulation. A PubMed bibliographic search matching the term 'cholangiocarcinoma' with 'experimental model', 'preclinical model', 'genetic target', 'targeted therapy', 'clinical trial', or 'translational research' was conducted and manuscripts published between 2010 and 2020 were retrieved for reading and reviewing.Expert opinion: Several factors contribute to the translational gap between bench research and clinical practice in CCA. The tumor heterogeneity, lack of a preclinical model recapitulating the different features of CCA, and difficult patient enrollment in clinical trials are elements to consider for basic and clinical research in CCA. Establishment of international networks formed by experts in the field of CCA may improve future research and its translational findings on patients.

Enhanced gemcitabine cytotoxicity with knockdown of multidrug resistance protein genes in human cholangiocarcinoma cell lines

BACKGROUND AND AIM

Cholangiocarcinoma (CCA) is an often fatal primary cancer of the liver that tends to be resistant to chemotherapy. Multidrug resistance proteins (MRPs) contribute to the chemoresistance of these tumors. The objectives of the study were to document MRP expression profiles in two representative human intrahepatic and extrahepatic CCA cells lines (HuCCT1 and KMBC, respectively) and gemcitabine-induced cytotoxicity prior to and following MRP knockdown.

METHODS

Multidrug resistance protein mRNA and protein expression were documented by real-time reverse transcription-polymerase chain reaction and western blots, respectively. MRP knockdown was achieved with lentivirus small hairpin RNA constructs.

RESULTS

Prior to gemcitabine exposure, MRP1, MRP2, MRP4, MRP5, and MRP6 mRNA were expressed in HuCCT1 cells and MRP1, MRP3, MRP4, and MRP5 in KMBC cells. Following gemcitabine exposure, MRP5 and MRP6 expressions were significantly upregulated in HuCCT1 cells and MRP5 in KMBC cells. In HuCCT1 cells, although MRP5 knockdown had no effect, MRP6 knockdown significantly increased gemcitabine-induced cytotoxicity. In KMBC cells, MRP5 knockdown significantly increased gemcitabine cytotoxicity.

CONCLUSIONS

Inhibition of MRP6 expression in intra-hepatic and MRP5 in extra-hepatic should be explored as potential treatments for CCA in humans.

Sulfasalazine modifies metabolic profiles and enhances cisplatin chemosensitivity on cholangiocarcinoma cells in in vitro and in vivo models

Background

Sulfasalazine (SSZ) is widely known as an xCT inhibitor suppressing CD44v9-expressed cancer stem-like cells (CSCs) being related to redox regulation. Cholangiocarcinoma (CCA) has a high recurrence rate and no effective chemotherapy. A recent report revealed high levels of CD44v9-positive cells in CCA patients. Therefore, a combination of drugs could prove a suitable strategy for CCA treatment via individual metabolic profiling.

Methods

We examined the effect of xCT-targeted CD44v9-CSCs using sulfasalazine combined with cisplatin (CIS) or gemcitabine in CCA in vitro and in vivo models and did NMR-based metabolomics analysis of xenograft mice tumor tissues.

Results

Our findings suggest that combined SSZ and CIS leads to a higher inhibition of cell proliferation and induction of cell death than CIS alone in both in vitro and in vivo models. Xenograft mice showed that the CD44v9-CSC marker and CK-19-CCA proliferative marker were reduced in the combination treatment. Interestingly, different metabolic signatures and significant metabolites were observed in the drug-treated group compared with the control group that revealed the cancer suppression mechanisms.

Conclusions

SSZ could improve CCA therapy by sensitization to CIS through killing CD44v9-positive cells and modifying the metabolic pathways, in particular tryptophan degradation (i.e., kynurenine pathway, serotonin pathway) and nucleic acid metabolism.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40170-021-00249-6.

The antiproliferative effects of ataxia-telangiectasia mutated and ATM- and Rad3-related inhibitions and their enhancements with the cytotoxicity of DNA damaging agents in cholangiocarcinoma cells

OBJECTIVE

To investigate whether the inhibitions of ataxia-telangiectasia mutated (ATM) and ATM- and Rad3-related (ATR) kinases by their specific inhibitors, KU-55933 and VE-821, respectively, are able to promote the cytotoxic activity of genotoxic agents including gemcitabine, 5-Fluorouracil, cisplatin and doxorubicin, in cholangiocarcinoma (CCA) and immortalized cholangiocyte cell lines.

METHODS

Cell viability of cells treated with DNA damaging agents, alone and in combination with KU-55933 and VE-821, was determined by MTT assay. The changes of cell cycle distribution were evaluated by flow cytometry analysis. Colony formation was conducted to assess the effects of KU-55933 and VE-821 on cell proliferation. The levels of protein expression and phosphorylation were examined by western blot analysis.

KEY FINDINGS

The cytotoxic effects of DNA damaging agents varied among CCA cell lines. Each DNA damaging drug induced different phases of the cell cycle in CCA cells. The combinations of both KU-55933 and VE-821 with DNA damaging agents promoted more cytotoxic activity than single inhibition in some CCA cell lines. ATM and ATR inhibitors decreased the effects of DNA damaging agent-induced ATM-Chk2 and ATR-Chk1 activations in CCA cells.

CONCLUSIONS

Inhibitions of ATM and ATR potentiated the cytotoxic effects of DNA damaging agents in CCA cells, especially p53 defective HuCCA1 and RMCC1 cell lines.

Cellular Mechanisms Accounting for the Refractoriness of Colorectal Carcinoma to Pharmacological Treatment

Simple Summary

Colorectal cancer (CRC) causes a high number (more than 800,000) of deaths worldwide each year. Better methods for early diagnosis and the development of strategies to enhance the efficacy of the therapeutic approaches used to complement or substitute surgical removal of the tumor are urgently needed. Currently available pharmacological armamentarium provides very moderate benefits to patients due to the high resistance of tumor cells to respond to anticancer drugs. The present review summarizes and classifies into seven groups the cellular and molecular mechanisms of chemoresistance (MOC) accounting for the failure of CRC response to the pharmacological treatment.

Abstract

The unsatisfactory response of colorectal cancer (CRC) to pharmacological treatment contributes to the substantial global health burden caused by this disease. Over the last few decades, CRC has become the cause of more than 800,000 deaths per year. The reason is a combination of two factors: (i) the late cancer detection, which is being partially solved by the implementation of mass screening of adults over age 50, permitting earlier diagnosis and treatment; (ii) the inadequate response of advanced unresectable tumors (i.e., stages III and IV) to pharmacological therapy. The latter is due to the existence of complex mechanisms of chemoresistance (MOCs) that interact and synergize with each other, rendering CRC cells strongly refractory to the available pharmacological regimens based on conventional chemotherapy, such as pyrimidine analogs (5-fluorouracil, capecitabine, trifluridine, and tipiracil), oxaliplatin, and irinotecan, as well as drugs targeted toward tyrosine kinase receptors (regorafenib, aflibercept, bevacizumab, cetuximab, panitumumab, and ramucirumab), and, more recently, immune checkpoint inhibitors (nivolumab, ipilimumab, and pembrolizumab). In the present review, we have inventoried the genes involved in the lack of CRC response to pharmacological treatment, classifying them into seven groups (from MOC-1 to MOC-7) according to functional criteria to identify cancer cell weaknesses. This classification will be useful to pave the way for developing sensitizing tools consisting of (i) new agents to be co-administered with the active drug; (ii) pharmacological approaches, such as drug encapsulation (e.g., into labeled liposomes or exosomes); (iii) gene therapy interventions aimed at restoring the impaired function of some proteins (e.g., uptake transporters and tumor suppressors) or abolishing that of others (such as export pumps and oncogenes).

Cholangiocarcinoma 2020: the next horizon in mechanisms and management

Cholangiocarcinoma (CCA) includes a cluster of highly heterogeneous biliary malignant tumours that can arise at any point of the biliary tree. Their incidence is increasing globally, currently accounting for ~15% of all primary liver cancers and ~3% of gastrointestinal malignancies. The silent presentation of these tumours combined with their highly aggressive nature and refractoriness to chemotherapy contribute to their alarming mortality, representing ~2% of all cancer-related deaths worldwide yearly. The current diagnosis of CCA by non-invasive approaches is not accurate enough, and histological confirmation is necessary. Furthermore, the high heterogeneity of CCAs at the genomic, epigenetic and molecular levels severely compromises the efficacy of the available therapies. In the past decade, increasing efforts have been made to understand the complexity of these tumours and to develop new diagnostic tools and therapies that might help to improve patient outcomes. In this expert Consensus Statement, which is endorsed by the European Network for the Study of Cholangiocarcinoma, we aim to summarize and critically discuss the latest advances in CCA, mostly focusing on classification, cells of origin, genetic and epigenetic abnormalities, molecular alterations, biomarker discovery and treatments. Furthermore, the horizon of CCA for the next decade from 2020 onwards is highlighted.

MRP3-Mediated Chemoresistance in Cholangiocarcinoma: Target for Chemosensitization Through Restoring SOX17 Expression

BACKGROUND AND AIMS

A limitation for the treatment of unresectable cholangiocarcinoma (CCA) is its poor response to chemotherapy, which is partly due to reduction of intracellular levels of anticancer drugs through ATP-binding cassette (ABC) pumps. Low expression of SOX17 (SRY-box containing gene 17), a transcription factor that promotes biliary differentiation and phenotype maintenance, has been associated with cholangiocyte malignant transformation. Whether SOX17 is also involved in CCA chemoresistance is investigated in this study.

APPROACH AND RESULTS

SOX17 expression in human CCA cells (EGI-1 and TFK-1) selectively potentiated cytotoxicity of SN-38, 5-fluorouracil and mitoxantrone, but not that of gemcitabine, capecitabine, cisplatin, or oxaliplatin. The analysis of the resistome by TaqMan low-density arrays revealed changes affecting primarily ABC pump expression. Single-gene quantitative real-time PCR, immunoblot, and immunofluorescence analyses confirmed that MRP3 (multidrug resistance associated protein 3), which was highly expressed in CCA human tumors, was down-regulated in SOX17-transduced CCA cells. The substrate specificity of this pump matched that of SOX17-induced in vitro selective chemosensitization. Functional studies showed lower ability of SOX17-expressing CCA cells to extrude specific MRP3 substrates. Reporter assay of MRP3 promoter (ABCC3pr) revealed that ABCC3pr activity was inhibited by SOX17 expression and SOX2/SOX9 silencing. The latter was highly expressed in CCA. Moreover, SOX2/9, but not SOX17, induced altered electrophoretic mobility of ABCC3pr, which was prevented by SOX17. The growth of CCA tumors subcutaneously implanted into immunodeficient mice was inhibited by 5-fluorouracil. This effect was enhanced by co-treatment with adenoviral vectors encoding SOX17.

CONCLUSIONS

SOX9/2/17 are involved in MRP3-mediated CCA chemoresistance. Restored SOX17 expression, in addition to its tumor suppression effect, induces selective chemosensitization due to MRP3 down-regulation and subsequent intracellular drug accumulation.

Evolution of the Experimental Models of Cholangiocarcinoma

Cholangiocarcinoma (CCA) is a rare, aggressive disease with poor overall survival. In advanced cases, surgery is often not possible or fails; in addition, there is a lack of effective and specific therapies. Multidisciplinary approaches and advanced technologies have improved the knowledge of CCA molecular pathogenesis, highlighting its extreme heterogeneity and high frequency of genetic and molecular aberrations. Effective preclinical models, therefore, should be based on a comparable level of complexity. In the past years, there has been a consistent increase in the number of available CCA models. The exploitation of even more complex CCA models is rising. Examples are the use of CRISPR/Cas9 or stabilized organoids for in vitro studies, as well as patient-derived xenografts or transgenic mouse models for in vivo applications. Here, we examine the available preclinical CCA models exploited to investigate: (i) carcinogenesis processes from initiation to progression; and (ii) tools for personalized therapy and innovative therapeutic approaches, including chemotherapy and immune/targeted therapies. For each model, we describe the potential applications, highlighting both its advantages and limits.

A review of systemic therapy in biliary tract carcinoma

Biliary tract carcinoma (BTC) has a poor prognosis and is increasing in incidence. Although surgery, chemotherapy and other treatment modalities have improved, surgery remains the only potential curative treatment and is appropriate for only those few patients who present with localized, resectable disease. However, for the majority of patients, unresectable disease is evident at diagnosis and about 95% of patients die within 10 years, despite the majority receiving chemotherapy. Long-term survival is significantly greater for patients with resected BTC compared to those with unresectable disease. In unresected disease, life expectancy is limited, with first-line gemcitabine/cisplatin (GEM/CIS) accepted as standard of care. Currently no standard second-line regimen which provides significant improvement of clinical outcomes exists for those who present with refractory disease or who relapse after first-line treatment. Of particular importance is establishing the impact of best supportive care (BSC) as a benchmark for survival outcomes to which the impact of treatment modalities can be compared. Survival outcome often differs significantly for patients with different prognostic factor profiles even when receiving the same therapy so that it can be difficult to predict which patient subgroup might benefit most from which therapy. Therefore, the influence of prognostic factors on survival under different therapies as well as under BSC needs to be further assessed in order to arrive at truly evidence-based, best therapeutic decisions for individual patients. Encouraging new research into the genomic landscape of BTC may help to further subdivide the BTC population into molecular-genetic clusters likely to be sensitive to different targeted therapy approaches leading to further improvements in survival. Consequently, an unmet need exists not only to develop new and more effective therapies for this devastating disease, but also to integrate original research findings into a more complex, dynamic, individualized therapeutic decision model to aid clinicians in making evidence-based, best therapeutic decisions for individual patients.

Inhibition of topoisomerase IIα and induction of DNA damage in cholangiocarcinoma cells by altholactone and its halogenated benzoate derivatives

Topoisomerase IIα enzyme (Topo IIα) plays a critical function in DNA replication process and is considered to be a promising target of anti-cancer drugs. In the present study, we reported that the altholactone derivatives modified by adding a halogenated benzoate group showed greater inhibitory activity on Topo IIα enzyme in cell-free system concomitant with cytotoxicity against the CCA cell lines (KKU-M055 and KKU-M213) than those of the parent altholactone. However, the cytotoxic activities of four halogenated benzoate altholactone derivatives including iodo-, fluoro-, chloro-, and bromobenzoate derivatives (compound 1, 2, 3, and 4, respectively) were of equal potency. The fluorobenzoate derivative (compound 2) was chosen for investigating the underlying mechanism in CCA cells. Compound 2 arrested CCA cell cycle at sub G1 phase and induced apoptotic cell death. It markedly inhibited Topo IIα protein expression in both KKU-M055 and KKU-M213 cells, which was accompanied by DNA double-strand breaks demonstrated by an increase in phosphorylated H2A.X protein. Interestingly, KKU-M055 cells, which express higher Topo IIα mRNA compared to KKU-M213 cells, showed greater sensitivity to the compound, indicating the selectivity of the compound to Topo IIα enzyme. By computational docking analysis, the binding affinity of altholactone (-52.5 kcal/mol) and compound 2 (-56.7 kcal/mol) were similar to that of the Topo II poison salvicine (-53.7 kcal/mol). The aromatic moiety of both altholactones embedded in a hydrophobic pocket of Topo II ATPase domain. In addition, compound 2 induced the formation of linear DNA in Topo II-mediated cleavage assay. Collectively, our results demonstrate that the addition of fluorobenzoyl group to altholactone enhances potency and selectivity to inhibit type IIα topoisomerases. Atholactone and fluorobenzoate derivative act as Topo II cleavage complexes stabilizing compounds or Topo II poisons preferentially through binding at ATPase domain of Topo IIα, leading to DNA double-strand breaks and apoptosis induction. Such activity of 3-fluorobenzoate derivative of altholactone should be further explored for the development of an anti-cancer drug for CCA.

Functional and genetic characterization of three cell lines derived from a single tumor of an Opisthorchis viverrini-associated cholangiocarcinoma patient

Three cholangiocarcinoma (CCA) cell line-formerly named, M156, M213 and M214 have been intensively used with discrepancy of their tumor origins. They were assumed to be originated from three different donors without authentication. To verify the origins of these cell lines, the short tandem repeat (STR) analysis of the currently used cell lines, the cell stocks from the establisher and the primary tumor of a CCA patient were performed. Their phenotypic and genotypic originality were compared. The currently used 3 CCA cell lines exhibited similar STR as CCA patient ID-M213 indicating the same origin of these cells. The cell stocks from the establisher, however, revealed the same STR of M213 and M214 cells, but not M156. The misidentification of M214 and M156 is probably due to the mislabeling and cross-contamination of M213 cells during culture. These currently used cell lines were renamed as KKU-213A, -213B and -213C, for the formerly M213, M214 and M156 cells, respectively. These cell lines were established from a male with an intrahepatic mass-forming CCA stage-4B. The tumor was an adenosquamous carcinoma with the liver fluke ova granuloma in evidence. All cell lines had positive CK19 with differential CA19-9 expression. They exhibited aneuploidy karyotypes, distinct cell morphology, cell growth, cytogenetic characteristic and progressive phenotypes. KKU-213C formed a adenosquamous carcinoma, whereas KKU-213A and KKU-213B formed poorly- and well-differentiated squamous cell carcinomas in xenografted mice. mRNA microarray revealed different expression profiles among these three cell lines. The three cell lines have unique characteristics and may resemble the heterogeneity of tumor origin.

Plasma Membrane Transporters as Biomarkers and Molecular Targets in Cholangiocarcinoma

The dismal prognosis of patients with advanced cholangiocarcinoma (CCA) is due, in part, to the extreme resistance of this type of liver cancer to available chemotherapeutic agents. Among the complex mechanisms accounting for CCA chemoresistance are those involving the impairment of drug uptake, which mainly occurs through transporters of the superfamily of solute carrier (SLC) proteins, and the active export of drugs from cancer cells, mainly through members of families B, C and G of ATP-binding cassette (ABC) proteins. Both mechanisms result in decreased amounts of active drugs able to reach their intracellular targets. Therefore, the “cancer transportome”, defined as the set of transporters expressed at a given moment in the tumor, is an essential element for defining the multidrug resistance (MDR) phenotype of cancer cells. For this reason, during the last two decades, plasma membrane transporters have been envisaged as targets for the development of strategies aimed at sensitizing cancer cells to chemotherapy, either by increasing the uptake or reducing the export of antitumor agents by modulating the expression/function of SLC and ABC proteins, respectively. Moreover, since some elements of the transportome are differentially expressed in CCA, their usefulness as biomarkers with diagnostic and prognostic purposes in CCA patients has been evaluated.

Adenosine Suppresses Cholangiocarcinoma Cell Growth and Invasion in Equilibrative Nucleoside Transporters-Dependent Pathway

Cholangiocarcinoma (CCA) is a lethal disease with increasing incidence worldwide. Previous study showed that CCA was sensitive to adenosine. Thereby, molecular mechanisms of CCA inhibition by adenosine were examined in this study. Our results showed that adenosine inhibited CCA cells via an uptake of adenosine through equilibrative nucleoside transporters (ENTs), instead of activation of adenosine receptors. The inhibition of ENTs by NBTI caused the inhibitory effect of adenosine to subside, while adenosine receptor antagonists, caffeine and CGS-15943, failed to do so. Intracellular adenosine level was increased after adenosine treatment. Also, a conversion of adenosine to AMP by adenosine kinase is required in this inhibition. On the other hand, inosine, which is a metabolic product of adenosine has very little inhibitory effect on CCA cells. This indicates that a conversion of adenosine to inosine may reduce adenosine inhibitory effect. Furthermore, there was no specific correlation between level of proinflammatory proteins and CCA responses to adenosine. A metabolic stable analog of adenosine, 2Cl-adenosine, exerted higher inhibition on CCA cell growth. The disturbance in intracellular AMP level also led to an activation of 5′ AMP-activated protein kinase (AMPK). Accordingly, we proposed a novel adenosine-mediated cancer cell growth and invasion suppression via a receptor-independent mechanism in CCA.

Genomic Profiling of Biliary Tract Cancer Cell Lines Reveals Molecular Subtypes and Actionable Drug Targets

Biliary tract cancers (BTCs) currently have no approved targeted therapies. Although genomic profiling of primary BTCs has identified multiple potential drug targets, accurate models are needed for their evaluation. Genomic profiling of 22 BTC cell lines revealed they harbor similar mutational signatures, recurrently mutated genes, and genomic alterations to primary tumors. Transcriptomic profiling identified two major subtypes, enriched for epithelial and mesenchymal genes, which were also evident in patient-derived organoids and primary tumors. Interrogating these models revealed multiple mechanisms of MAPK signaling activation in BTC, including co-occurrence of low-activity BRAF and MEK mutations with receptor tyrosine kinase overexpression. Finally, BTC cell lines with altered ERBB2 or FGFRs were exquisitely sensitive to specific targeted agents, whereas surprisingly, IDH1-mutant lines did not respond to IDH1 inhibitors in vitro. These findings establish BTC cell lines as robust models of primary disease, reveal specific molecular disease subsets, and highlight specific molecular vulnerabilities in these cancers.

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BTC cell lines harbor similar genomic alterations to primary tumors

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Transcriptomic profiling of BTC cell lines identified two molecular subtypes

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MAPK signaling is activated in BTC via multiple mechanisms

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BTC lines with deregulated ERBB2 or FGFRs respond to specific targeted therapies

Models for Understanding Resistance to Chemotherapy in Liver Cancer

The lack of response to pharmacological treatment constitutes a substantial limitation in the handling of patients with primary liver cancers (PLCs). The existence of active mechanisms of chemoresistance (MOCs) in hepatocellular carcinoma, cholangiocarcinoma, and hepatoblastoma hampers the usefulness of chemotherapy. A better understanding of MOCs is needed to develop strategies able to overcome drug refractoriness in PLCs. With this aim, several experimental models are commonly used. These include in vitro cell-free assays using subcellular systems; studies with primary cell cultures; cancer cell lines or heterologous expression systems; multicellular models, such as spheroids and organoids; and a variety of in vivo models in rodents, such as subcutaneous and orthotopic tumor xenografts or chemically or genetically induced liver carcinogenesis. Novel methods to perform programmed genomic edition and more efficient techniques to isolate circulating microvesicles offer new opportunities for establishing useful experimental tools for understanding the resistance to chemotherapy in PLCs. In the present review, using three criteria for information organization: (1) level of research; (2) type of MOC; and (3) type of PLC, we have summarized the advantages and limitations of the armamentarium available in the field of pharmacological investigation of PLC chemoresistance.

The combination of BET and PARP inhibitors is synergistic in models of cholangiocarcinoma

Our previous finding that the BET inhibitor (BETi) JQ1 increases levels of the DNA damage marker γH2AX suggested that JQ1 might enhance the sensitivity of tumor cells to PARP inhibitors (PARPi), which are selectively toxic to cells that harbor relatively high levels of DNA damage. To address this hypothesis, we evaluated the effect of a BETi (JQ1 or I-BET762) combined with a PARPi (olaparib or veliparib) in KKU-055 and KKU-100 cholangiocarcinoma (CCA) cell lines and of JQ1 with olaparib in a xenograft model of CCA. Each combination was more effective than any of the four drugs as single agents. Combination indices ranged from 0.1 to 0.8 at the ED50 for all combinations, indicating synergy and demonstrating that synergy was not limited to a specific combination. Mechanistically, downregulation of BETi molecular targets BRD2 or BRD4 by shRNA sensitized CCA cells to BETi as single agents as well as to the combination of a BETi + a PARPi. Our data indicate that combinations of a BETi with a PARPi merit further evaluation as a promising strategy for CCA.

Role of transportome in the pharmacogenomics of hepatocellular carcinoma and hepatobiliary cancer

An important factor determining the pharmacological response to antitumor drugs is their concentrations in cancer cells, which accounts for the net interaction with their intracellular molecular targets. Accordingly, mechanisms leading to reduced intracellular levels of active agents play a crucial role in cancer chemoresistance. These include impaired drug uptake through solute carrier (SLC) proteins and efficient drug export by ATP-dependent pumps belonging to the ATP-binding cassette (ABC) superfamily of proteins. Since the net movement of drugs in-and-out the cells depends on the overall expression of carrier proteins, defining the so-called transportome, special attention has been devoted to the study of transcriptome regarding these proteins. Nevertheless, genetic variants affecting SLC and ABC genes may markedly affect the bioavailability and, hence, the efficacy of anticancer drugs.

Signalling networks in cholangiocarcinoma: Molecular pathogenesis, targeted therapies and drug resistance

Cholangiocarcinoma (CCA) is a deadly disease. While surgery may attain cure in a minor fraction of cases, therapeutic options in either the adjuvant or advanced setting are limited. The possibility of advancing the efficacy of therapeutic approaches to CCA relies on understanding its molecular pathogenesis and developing rational therapies aimed at interfering with oncogenic signalling networks that drive and sustain cholangiocarcinogenesis. These efforts are complicated by the intricate biology of CCA, which integrates not only the driving force of tumour cell-intrinsic alterations at the genetic and epigenetic level but also pro-tumorigenic cues conveyed to CCA cells by different cell types present in the rich tumour stroma. Herein, we review our current understanding of the mechanistic bases underpinning the activation of major oncogenic pathways causative of CCA pathogenesis. We subsequently discuss how this knowledge is being exploited to implement rationale-based and genotype-matched therapeutic approaches that predictably will radically transform CCA clinical management in the next decade. We conclude by highlighting the mechanisms of therapeutic resistance in CCA and reviewing innovative approaches to combat resistance at the preclinical and clinical level.

Mitochondrial division inhibitor-1 potentiates cisplatin-induced apoptosis via the mitochondrial death pathway in cholangiocarcinoma cells

AIMS

Mdivi-1, a selective Drp-1 inhibitor, impedes mitochondrial dynamics and suppresses cancer proliferation and progression. Cholangiocarcinoma (CCA) is a very aggressive malignancy which is refractory to chemotherapy. The study investigated the mechanism of the chemosensitizing effect of mdivi-1 in cholangiocarcinoma.

MAIN METHODS

CCA cells and HEK293 T cells were employed in the study. Cell viability and induction of apoptotic cell death were determined by the MTT and acridine orange-ethidium bromide methods. Cellular glutathione content and reactive oxygen species (ROS) formation were assessed using thiol green and 2',7'-dichlorofluorescin diacetate fluorescent probes, respectively. Mitochondrial transmembrane potential and autophagy were detected by JC-1 dye and autophagy assay. Cell cycle progression was analyzed by flow cytometry. Cell migration was measured using the wound healing assay. Proteins involved in cell proliferation and cell cycle were analyzed by western immunoblotting.

KEY FINDINGS

Mdivi-1 enhanced cisplatin-induced cytotoxicity in CCA cells but not in HEK293 T cells. Mdivi-1 enhanced cisplatin induced glutathione redox stress, ROS formation, and loss of mitochondrial transmembrane potential. Moreover, mdivi-1 also inhibited autophagic flux and suppressed CCA cell migration.

SIGNIFICANCE

Mdivi-1 sensitized CCA cells to cytotoxicity of cisplatin in association with increases of oxidative stress and autophagosomes, and induced cell death via the mitochondrial pathway. Disruption of mitochondrial dynamics may be a novel strategy to improve the efficacy of chemotherapy to treat CCA.

FOXM1 modulates 5-fluorouracil sensitivity in cholangiocarcinoma through thymidylate synthase (TYMS): implications of FOXM1-TYMS axis uncoupling in 5-FU resistance

Fluorouracil (5-FU) is the first-line chemotherapeutic drug for cholangiocarcinoma (CCA), but its efficacy has been compromised by the development of resistance. Development of 5-FU resistance is associated with elevated expression of its cellular target, thymidylate synthase (TYMS). E2F1 transcription factor has previously been shown to modulate the expression of FOXM1 and TYMS. Immunohistochemical (IHC) analysis revealed a strong correlated upregulation of FOXM1 (78%) and TYMS (48%) expression at the protein levels in CCA tissues. In agreement, RT-qPCR and western blot analyses of four human CCA cell lines at the baseline level and in response to high doses of 5-FU revealed good correlations between FOXM1 and TYMS expression in the CCA cell lines tested, except for the highly 5-FU-resistant HuCCA cells. Consistently, siRNA-mediated knockdown of FOXM1 reduced the clonogenicity and TYMS expression in the relatively sensitive KKU-D131 but not in the highly resistant HuCCA cells. Interestingly, silencing of TYMS sensitized both KKU-D131 and HuCCA to 5-FU treatment, suggesting that resistance to very high levels of 5-FU is due to the inability of the genotoxic sensor FOXM1 to modulate TYMS expression. Consistently, ChIP analysis revealed that FOXM1 binds efficiently to the TYMS promoter and modulates TYMS expression at the promoter level upon 5-FU treatment in KKU-D131 but not in HuCCA cells. In addition, E2F1 expression did not correlate with either FOXM1 or TYMS expression and E2F1 depletion has no effects on the clonogenicity and TYMS expression in the CCA cells. In conclusion, our data show that FOXM1 regulates TYMS expression to modulate 5-FU resistance in CCA and that severe 5-FU resistance can be caused by the uncoupling of the regulation of TYMS by FOXM1. Our findings suggest that the FOXM1–TYMS axis can be a novel diagnostic, predictive and prognostic marker as well as a therapeutic target for CCA.

Cytotoxic activity and molecular targets of atractylodin in cholangiocarcinoma cells

Objectives

To evaluate the cytotoxic activity of atractylodin and its potential effects on heme oxygenase (HO)-1 production, STAT1/3 phosporylation and major NF-κB protein expression in the cholangiocarcinoma-associated cell line CL-6.

Methods

Standard MTT assay was used for accessing antiproliferative activity on CL-6 cells. Normal human embryonic fibroblast (OUMS) cell was taken as control cell line. Colony formation and wound healing assay were conducted to access the effects of atractylodin on cell proliferation and directional migration activity of CL-6 cells. Western blot was used for evaluating levels of protein expression and phosphorylation.

Key findings

Atractylodin exhibited selective cytotoxicity towards CL-6 as compared with OUMS with IC50 of 216.8 (212.4-233.8) and 351.2 (345.7-359.5) μm [median (range)], respectively. Exposure to the compound dose-dependently inhibited colony formation ability and decreased wound closure potential of CL-6 cells. Atractylodin treatment suppressed HO-1 production in CL-6 cells. It dose-dependently inhibited STAT1/3 protein phosphorylation and moderately inhibited NF-κB (p50), NF-κB (p52), and NF-κB (p65) protein expression in both dose- and time-dependent manner.

Conclusions

Atractylodin exerts significant cytotoxic activity against CL-6 cells which may be linked to its suppressive effect on HO-1 production, STAT1/3 phosphorylation and expression of key NF-κB proteins.

Dysregulated microRNA expression profiles in cholangiocarcinoma cell-derived exosomes

AIM

Cholangiocarcinoma (CCA) is a malignant tumor of bile duct epithelial cells. The prognosis of CCA is poor due to lack of effective therapeutic targets and detection at an advanced stage. Exosomes are secreted nano-sized vesicles and contribute to the malignancy of several cancers via transferring their miRNAs between cells. Thus, exosomal miRNAs may serve as new therapeutic targets and potential biomarkers for CCA.

MAIN METHODS

Exosomes were isolated from three different CCA cell lines and normal human cholangiocyte cells, followed by miRNA profiling analysis. Potential role of dysregulated miRNA was investigated by knockdown experiment.

KEY FINDINGS

We found that 38 and 460 miRNAs in CCA exosomes were significantly up- and down-regulated, respectively. Of these differentially expressed miRNAs, the hsa-miR-205-5p and miR-200 family members were markedly up-regulated for 600-1500 folds, whereas the miR-199 family members and their clustered miRNA, hsa-miR-214-3p, were down-regulated for 1000-2000 folds. The expression patterns of these representative exosomal miRNAs were similar to those observed in all types of CCA cells. The target genes of the top ten most up- and down-regulated miRNAs are significantly associated with well-characterized cancer-related pathways. Consistently, knockdown of the most up-regulated miRNA, miR-205-5p, reduced KKU-M213 cell invasion and migration.

SIGNIFICANCE

We have demonstrated the distinct miRNA signatures in exosomes released from CCA cells, compared to normal human cholangiocyte cells. These exosomal miRNAs may have the potential to be novel therapeutic targets and biomarkers for CCA.

Anthocyanin complex exerts anti-cholangiocarcinoma activities and improves the efficacy of drug treatment in a gemcitabine-resistant cell line

Cholangiocarcinoma (CCA) is a deleterious bile duct tumor with poor prognosis and is relatively resistant to chemotherapy. Therefore, alternative or supplementary agents with anticancer and chemosensitizing activities may be useful for the treatment of CCA. A novel anthocyanin complex (AC) nanoparticle, developed from extracts of cobs of purple waxy corn and petals of blue butterfly pea, has exhibited chemopreventive potential in vivo. In the present study, the anti-CCA activities of AC and their underlying molecular mechanisms were investigated further in vitro using a CCA cell line (KKU213). The potential use of AC as a chemosensitizer was also evaluated in a gemcitabine-resistant CCA cell line (KKU214GemR). It was demonstrated that AC treatment suppressed proliferation of KKU213 CCA cells in dose- and time-dependent manners. AC treatment also induced apoptosis and mitochondrial superoxide production, decreased clonogenicity of CCA cells, and downregulated forkhead box protein M1 (FOXM1), nuclear factor-κB (NF-κB) and pro-survival protein B-cell lymphoma-2 (Bcl-2). The expression of endoplasmic reticulum (ER) stress-response proteins, including protein kinase RNA-like ER kinase, phosphorylated eIF2α, eukaryotic initiation factor 2α and activating transcription factor 4, also decreased following AC treatment. It was also identified that AC treatment inhibited KKU214GemR cell proliferation in dose- and time-dependent manners. Co-treatment of KKU214GemR cells with low doses of AC together with gemcitabine significantly enhanced efficacy of the latter against this cell line. Therefore, it is suggested that AC treatment is cytotoxic to KKU213 cells, possibly via downregulation of FOXM1, NF-κB, Bcl-2 and the ER stress response, and by induction of mitochondrial superoxide production. AC also sensitizes KKU214GemR to gemcitabine treatment, which may have potential for overcoming drug resistance of CCA.

CG200745, an HDAC inhibitor, induces anti-tumour effects in cholangiocarcinoma cell lines via miRNAs targeting the Hippo pathway

Cholangiocarcinoma is a devastating malignancy with fatal complications that exhibits low response and resistance to chemotherapy. Here, we evaluated the anticancer effects of CG200745, a novel histone deacetylase inhibitor, either alone or in combination with standard chemotherapy drugs in cholangiocarcinoma cells. CG200745 dose-dependently reduced the viability of cholangiocarcinoma cells in vitro and decreased tumour volume and weight in a xenograft model. Administering CG200745 along with other chemotherapeutic agents including gemcitabine, 5-fluorouracil (5-FU), cisplatin, oxaliplatin, or gemcitabine plus cisplatin further decreased cholangiocarcinoma cell viability, with a combination index < 1 that indicated synergistic action. CG200745 also enhanced the sensitivity of gemcitabine-resistant cells to gemcitabine and 5-FU, thereby decreasing cell viability and inducing apoptosis. This was accompanied by downregulation of YAP, TEAD4, TGF-β2, SMAD3, NOTCH3, HES5, Axl, and Gas6 and upregulation of the miRNAs miR-22-3p, miR-22-5p, miR-194-5p, miR-194-3p, miR-194-5p, miR-210-3p, and miR-509-3p. The Ingenuity Pathway Analysis revealed that CG200745 mainly targets the Hippo signalling pathway by inducing miR-509-3p expression. Thus, CG200745 inhibits cholangiocarcinoma growth in vitro and in vivo, and acts synergistically when administered in combination with standard chemotherapeutic agents, enabling dose reduction. CG200745 is therefore expected to improve the outcome of cholangiocarcinoma patients who exhibit resistance to conventional therapies.

Growth inhibitory effect of β-eudesmol on cholangiocarcinoma cells and its potential suppressive effect on heme oxygenase-1 production, STAT1/3 activation, and NF-κB downregulation

Cholangiocarcinoma (CCA) is a progressively fatal form of cancer originating from the malignant transformation of hepatic biliary cholangiocytes. The present study reports for the first time in vitro growth inhibitory activities of β-eudesmol, the bioactive sesquiterpenoid present in the rhizome of Atractylodes lancea (Thunb) DC., with respect to its underlying potential effects on heme oxygenase-1 (HO-1) production, STAT1/3 phosphorylation, and NF-κB protein expression in human CCA cell line CL-6. The cytotoxic effect of β-eudesmol on CL-6 cells was evaluated by MTT assay using normal human embryonic fibroblast (OUMS) as a control cell line. Results indicated that β-eudesmol exhibited selective cytotoxicity towards CL-6 compared to OUMS with mean (±SD) IC₅₀ (concentration that inhibits cell growth by 50%) values of 166.75 ± 3.69 and 240.01 ± 16.54 μmol/L, respectively. In addition, it also significantly suppressed colony forming and wound healing ability of CL-6 cells in a concentration-dependent manner. Western blot analysis indicated that β-eudesmol treatment resulted in significant suppression of HO-1 production in CL-6 cells. Its inhibitory effects on the phosphorylation of STAT1/3 proteins and expression of NF-κB (p65 and p50) proteins were concentration-dependent. Taken together, these results suggest that β-eudesmol exerts significant growth inhibitory activity on CL-6 cells that may be linked to its inhibitory effect on the production of HO-1, phosphorylation of STAT1/3, and expression of major NF-κB proteins.

The search for novel diagnostic and prognostic biomarkers in cholangiocarcinoma

The poor prognosis of cholangiocarcinoma (CCA) is in part due to late diagnosis, which is currently achieved by a combination of clinical, radiological and histological approaches. Available biomarkers determined in serum and biopsy samples to assist in CCA diagnosis are not sufficiently sensitive and specific. Therefore, the identification of new biomarkers, preferably those obtained by minimally invasive methods, such as liquid biopsy, is important. The development of innovative technologies has permitted to identify a significant number of genetic, epigenetic, proteomic and metabolomic CCA features with potential clinical usefulness in early diagnosis, prognosis or prediction of treatment response. Potential new candidates must be rigorously evaluated prior to entering routine clinical application. Unfortunately, to date, no such biomarker has achieved validation for these purposes. This review is an up-to-date of currently used biomarkers and the candidates with promising characteristics that could be included in the clinical practice in the next future. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

Chemoresistance and chemosensitization in cholangiocarcinoma

One of the main difficulties in the management of patients with advanced cholangiocarcinoma (CCA) is their poor response to available chemotherapy. This is the result of powerful mechanisms of chemoresistance (MOC) of quite diverse nature that usually act synergistically. The problem is often worsened by altered MOC gene expression in response to pharmacological treatment. Since CCA includes a heterogeneous group of cancers their genetic signature coding for MOC genes is also diverse; however, several shared traits have been defined. Some of these characteristics are shared with other types of liver cancer, namely hepatocellular carcinoma and hepatoblastoma. An important goal in modern oncologic pharmacology is to develop novel strategies to overcome CCA chemoresistance either by increasing drug specificity, such as in targeted therapies aimed to inhibit receptors with tyrosine kinase activity, or to increase the amounts of active agents inside CCA cells by enhancing drug uptake or reducing efflux through export pumps. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

Targeting hexokinase II as a possible therapy for cholangiocarcinoma

Overexpression of hexokinase 2 (HKII) has been demonstrated in various cancers. A number of in vitro and in vivo studies in several cancers show the significance of HKII in many cellular processes including proliferation, metastasis and apoptosis. However, the role of HKII in Opisthorchis viverrini (Ov) associated cholangiocarcinoma (CCA) is still unknown. In the present study, the expression and roles of HKII were determined in Ov associated CCA. The expression of HKII was investigated in 82 patients with histologically proven CCAs by immunohistochemistry. HKII was distinctively expressed in CCA tissues. It was rarely expressed in normal bile duct epithelium, but was expressed in hyperplastic/dysplastic and in 82% of CCA bile ducts. The observation was confirmed in the Ov associated hamster model. Suppression of HKII expression using siRNA significantly decreased cell proliferation, migration and invasion of CCA cell lines. Similar results were obtained using lonidamine (LND), an inhibitor of HK. LND significantly inhibited growth of 4 CCA cell lines tested in dose and time dependent fashion. Comparison the cytotoxic effects of LND and siRNA-HKII suggests the off target of LND above 100 μM. In addition, LND in non-cytotoxic doses could suppress migration and invasion of CCA cells. These results indicate the association of HKII in cholangiocarcinogenesis and progression and suggest the possibility of HKII as a therapeutic target for CCA.

Identification of biomarkers of intrahepatic cholangiocarcinoma via integrated analysis of mRNA and miRNA microarray data

The present study aimed to identify potential therapeutic targets of intrahepatic cholangiocarcinoma (ICC) via integrated analysis of gene (transcript version) and microRNA (miRNA/miR) expression. The miRNA microarray dataset GSE32957 contained miRNA expression data from 16 ICC, 7 mixed type of combined hepatocellular-cholangiocarcinoma (CHC), 2 hepatic adenoma, 3 focal nodular hyperplasia (FNH) and 5 healthy liver tissue samples, and 2 cholangiocarcinoma cell lines. In addition, the mRNA microarray dataset GSE32879 contained mRNA expression data from 16 ICC, 7 CHC, 2 hepatic adenoma, 5 FNH and 7 healthy liver tissue samples. The datasets were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) and miRNAs (DEMs) in ICC samples compared with healthy liver tissues were identified via the limma package, following data preprocessing. Genes that exhibited alternative splicing (AS) in ICC samples were identified via AltAnalyze software. Functional enrichment analysis of DEGs was performed using the Database for Annotation, Visualization and Integrated Analysis. Target genes of DEMs were identified using the TargetScan database. The regulatory association between DEMs and any overlaps among DEGs, alternative splicing genes (ASGs) and target genes of DEMs were retrieved, and a network was visualized using the Cytoscape software. A total of 2,327 DEGs, 70 DEMs and 623 ASGs were obtained. Functional enrichment analysis indicated that DEGs were primarily enriched in biological processes and pathways associated with cell activity or the immune system. A total of 63 overlaps were obtained among DEGs, ASGs and target genes of DEMs, and a regulation network that contained 243 miRNA-gene regulation pairs was constructed between these overlaps and DEMs. The overlapped genes, including sprouty-related EVH1 domain containing 1, protein phosphate 1 regulatory subunit 12A, chromosome 20 open reading frame 194, and DEMs, including hsa-miR-96, hsa-miR-1 and hsa-miR-25, may be potential therapeutic targets for the future treatment of ICC.

Gold Nanoparticles Enhance the Anticancer Activity of Gallic Acid against Cholangiocarcinoma Cell Lines

Gold nanoparticles (GNPs) were conjugated with gallic acid (GA) at various concentrations between 30 and 150 μM and characterized using transmission electron microscopy (TEM) and UV-Vis spectroscopy (UV-VIS). The anticancer activities of the gallic acid-stabilized gold nanoparticles against well-differentiated (M213) and moderately differentiated (M214) adenocarcinomas were then determined using a neutral red assay. The GA mechanism of action was evaluated using Fourier transform infrared (FTIR) microspectroscopy. Distinctive features of the FTIR spectra between the control and GA-treated cells were confirmed by principal component analysis (PCA). The surface plasmon resonance spectra of the GNPs had a maximum absorption at 520 nm, whereas GNPs-GA shifted the maximum absorption values. In an in vitro study, the complexed GNPs-GA had an increased ability to inhibit the proliferation of cancer cells that was statistically significant (P<0.0001) in both M213 and M214 cells compared to GA alone, indicating that the anticancer activity of GA can be improved by conjugation with GNPs. Moreover, PCA revealed that exposure of the tested cells to GA resulted in significant changes in their cell membrane lipids and fatty acids, which may enhance the efficacy of this anticancer activity regarding apoptosis pathways.

Expert consensus document: Cholangiocarcinoma: current knowledge and future perspectives consensus statement from the European Network for the Study of Cholangiocarcinoma (ENS-CCA)

Cholangiocarcinoma (CCA) is a heterogeneous group of malignancies with features of biliary tract differentiation. CCA is the second most common primary liver tumour and the incidence is increasing worldwide. CCA has high mortality owing to its aggressiveness, late diagnosis and refractory nature. In May 2015, the "European Network for the Study of Cholangiocarcinoma" (ENS-CCA: www.enscca.org or www.cholangiocarcinoma.eu) was created to promote and boost international research collaboration on the study of CCA at basic, translational and clinical level. In this Consensus Statement, we aim to provide valuable information on classifications, pathological features, risk factors, cells of origin, genetic and epigenetic modifications and current therapies available for this cancer. Moreover, future directions on basic and clinical investigations and plans for the ENS-CCA are highlighted.

Corilagin suppresses cholangiocarcinoma progression through Notch signaling pathway in vitro and in vivo

Corilagin is a natural plant polyphenol tannic acid with antitumor, anti-inflammatory, and anti-oxidative properties. However, the mechanisms of its actions are largely unknown. Our group reported that corilagin could induce cell inhibition in human breast cancer cell line MCF-7 and human liver hepatocellular carcinoma cell lines HepG2. We report here that corilagin inhibits cholangiocarcinoma (CCA) development through regulating Notch signaling pathway. We found that, in vitro, corilagin inhibited CCA cell proliferation, migration and invasion, promoted CCA cell apoptosis, and inhibited Notch1 and Notch signaling pathway protein expression. Co-immunoprecipitation was used to establish Notch intracellular domain (NICD) interaction with MAML1 and P300 in CCA. Importantly, corilagin reduced Hes1 mRNA level through inhibiting Hes1 promoter activity. In nude mice, corilagin inhibited CCA growth and repressed the expression of Notch1 and mTOR. These results indicate that corilagin may control CCA cell growth by downregulating the expression of Notch1. Therefore, our findings suggest that corilagin may have the potential to become a new therapeutic drug for human CCA.

Histone deacetylase inhibitor screening identifies HC toxin as the most effective in intrahepatic cholangiocarcinoma cells

Histone deacetylases (HDACs) are highly expressed in intrahepatic cholangiocarcinoma (ICC) and are associated with poor prognosis of these patients. The aim of the present study was to explore the inhibitory effects of HDAC inhibitors on ICC cells and identify effective and sensitive drugs for ICC. Effects of 34 HDAC inhibitors were screened through two rounds of cell viability assays, and HC toxin, a cyclic tetrapeptide first isolated from the secondary metabolite of Helminthosporium carbonum, exhibited an antitumor activity superior to that of the other HDAC inhibitors and gemcitabine. The mechanisms involved in the inhibitory effects of HC toxin on CCLP-1 cells were investigated by cell counting, colony formation assay, cell morphological observation, real-time PCR, western blotting and flow cytometry. It was demonstrated that HC toxin inhibited the cell proliferation and clone formation ability of the CCLP-1 cells. HC toxin increased the acetyl-histone H4 level and this was associated with the inhibitory effect of HC toxin on the CCLP-1 cells. We also found that HC toxin reduced the level of HDAC1 protein in a post-transcriptional manner. Morphological observation showed multiple morphological changes and indicated the possibility of cell differentiation owing to HC toxin. With increasing concentration of HC toxin, the cell cycle was gradually arrested at the G0/G1 stage and the percentage of apoptotic cells increased which was not mainly through the caspase-3-dependent ways. These results indicated that HC toxin was the most effective among the various HDAC inhibitors with multiple functions in the suppression of ICC in vitro. Thus, HC may be a potential chemotherapeutic for ICC.

Gene silencing of galectin-3 changes the biological behavior of Eca109 human esophageal cancer cells

Galectin-3 is a multifunctional β-galactoside-binding lectin that is involved in multiple biological functions which are upregulated in malignancies, including cell growth, adhesion, proliferation, progression and metastasis, as well as apoptosis. A previous study has confirmed the roles of galecin-3 overexpression in the biological behavior of Eca109 human esophageal cancer (EC) cells. In the present study, small interfering (si)RNA-mediated galectin-3 silencing was performed to analyze the effects of decreased galectin-3 expression on the biological behavior of EC cells. Western blot and quantitative polymerase chain reaction analyses were utilized to confirm galectin-3 knockdown at the protein and mRNA level (P<0.05 vs. siRNA-control and untransfected groups). Cell proliferation was assessed using the Cell Counting Kit-8 assay. At 72 and 96 h after transfection, the proliferation of Eca109 cells in the siRNA-Gal-3 group was decreased compared with that in the siRNA-Control and untransfected groups (P<0.001 and P=0.004, respectively). Furthermore, Transwell assays demonstrated that inhibition of galecin-3 significantly reduced the migration and invasion of Eca109 cells compared with that in the other groups (P<0.05). Finally, apoptosis of Eca109 cells was detected using Annexin V/7-amino-actinomycin double-staining and flow cytometric analysis. Galectin-3 knockdown significantly enhanced the apoptotic rate of Eca109 cells compared with that in the siRNA-control and untreated groups (P=0.031 and P=0.047, respectively). In conclusion, following successful knockdown of galecin-3 expression in Eca109 cells, the cell proliferation, migration and invasion were reduced, while the apoptosis was enhanced, which indicates that galectin silencing may represent a therapeutic strategy for EC.