Targeting Fatty Acid Synthase Modulates Metabolic Pathways and Inhibits Cholangiocarcinoma Cell Progression.

An aberrant regulation of lipid metabolism is involved in the pathogenesis and progression of cancer. Up-regulation of lipid biosynthesis enzymes, including acetyl-CoA carboxylase (ACC), fatty acid synthase (FASN) and HMG-CoA reductase (HMGCR), has been reported in many cancers. Therefore, elucidating lipid metabolism changes in cancer is essential for the development of novel therapeutic targets for various human cancers. The current study aimed to identify the abnormal expression of lipid-metabolizing enzymes in cholangiocarcinoma (CCA) and to evaluate whether they can be used as the targets for CCA treatment. Our study demonstrated that a high expression of FASN was significantly correlated with the advanced stage in CCA patients. In addition, survival analysis showed that high expression of FASN and HMGCR was correlated with shorter survival of CCA patients. Furthermore, FASN knockdown inhibited the growth, migration and invasion in CCA cell lines, KKU055 and KKU213, as well as induced cell cycle arrest and apoptosis in the CCA cell lines. In addition, metabolomics study further revealed that purine metabolism was the most relevant pathway involved in FASN knockdown. Adenosine diphosphate (ADP), glutamine and guanine levels significantly increased in KKU213 cells while guanine and xanthine levels remarkably increased in KKU055 cells showing a marked difference between the control and FASN knockdown groups. These findings provide new insights into the mechanisms associated with FASN knockdown in CCA cell lines and suggest that targeting FASN may serve as a novel CCA therapeutic strategy.

Therapeutic challenges at the preclinical level for targeted drug development for Opisthorchis viverrini-associated cholangiocarcinoma.

INTRODUCTION: Cholangiocarcinoma (CCA) is a malignant tumor of bile duct epithelium with the highest incidence found in Thailand. Some patients are considered suitable for adjuvant therapy and surgical resection is currently the curative treatment for CCA patients. Tumor recurrence is still a hurdle after treatment; hence, finding novel therapeutic strategies to combat CCA is necessary for improving outcome for patients. AREAS COVERED: We discuss targeted therapies and other novel treatment approaches which include protein kinase inhibitors, natural products, amino acid transporter-based inhibitors, immunotherapy, and drug repurposing. We also examine the challenges of tumor heterogeneity, cancer stem cells (CSCs), the tumor microenvironment, exosomes, multiomics studies, and the potential of precision medicine. EXPERT OPINION: Because CCA is difficult to diagnose at the early stage, the traditional treatment approaches are not effective for many patients and most tumors recur. Consequently, researchers are exploring multi-aspect molecular carcinogenesis to uncover molecular targets for further development of novel targeted drugs.

CD44 modulates metabolic pathways and altered ROS-mediated Akt signal promoting cholangiocarcinoma progression.

CD44 is a transmembrane glycoprotein, the phosphorylation of which can directly trigger intracellular signaling, particularly Akt protein, for supporting cell growth, motility and invasion. This study examined the role of CD44 on the progression of Cholangiocarcinoma (CCA) using metabolic profiling to investigate the molecular mechanisms involved in the Akt signaling pathway. Our results show that the silencing of CD44 decreases Akt and mTOR phosphorylation resulting in p21 and Bax accumulation and Bcl-2 suppression that reduces cell proliferation. Moreover, an inhibition of cell migration and invasion regulated by CD44. Similarly, the silencing of CD44 showed an alteration in the epithelial-mesenchymal transition (EMT), e.g. an upregulation of E-cadherin and a downregulation of vimentin, and the reduction of the matrix metalloproteinase (MMP)-9 signal. Interestingly, a depletion of CD44 leads to metabolic pathway changes resulting in redox status modification and Trolox (anti-oxidant) led to the recovery of the cancer cell functions. Based on our findings, the regulation of CCA progression and metastasis via the redox status-related Akt signaling pathway depends on the alteration of metabolic profiling synchronized by CD44.

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.

Metabolic Profiling of Praziquantel-mediated Prevention of Opisthorchis viverrini-induced Cholangiocyte Transformation in the Hamster Model of Cholangiocarcinoma.

BACKGROUND: Opisthorchis viverrini (Ov) infection-induced cholangiocarcinoma (CCA) is a major public health problem in northeastern Thailand. Praziquantel was shown to prevent CCA development in an Ov-infected hamster model; however, the molecular mechanism remains unknown. MATERIALS AND METHODS: In this study, we used a hamster model with Ov and N-nitrosodimethylamine-induced CCA to study the mechanisms of praziquantel action. The liver tissues from the hamsters with and without praziquantel treatment were analyzed using 1H nuclear magnetic resonance spectroscopy. RESULTS: A total of 14 metabolites were found to be significantly different between the two groups. Furthermore, the combination of acetate, inosine and sarcosine was shown to exert an anti-inflammatory effect through interleukin-6 inhibition in a macrophage cell line, suggesting a mechanism by which praziquantel may prevent inflammation caused by Ov, cholangiocyte transformation and further CCA develpoment. CONCLUSION: These findings might avail the development of a preventive strategy for CCA in high-risk populations.

Serum IgG as a Marker for Opisthorchis viverrini-Associated Cholangiocarcinoma Correlated with HER2 Overexpression.

BACKGROUND: Serum antibody for Opisthorchis viverrini (OV) is strong evidence for a history of OV infection in people. Currently, no studies have examined whether varying cholangiocarcinoma (CCA) prevalence levels are linked to previous OV infection nor have they provided comprehensive assessment and characterization of OV-associated CCA. OBJECTIVE: Our study examined the prevalence of serum IgG antibodies for OV-positive CCA cases and determined whether there were correlations of IgG antibodies with histopathologic features, HER2, PD-L1, and FGFR2 expression, as well as their roles on the patients' survival. METHODS: The study involved 221 CCA surgical patients at Khon Kaen University Hospital, Thailand, from 2005 to 2017. Serum specimens were tested for OV IgG by ELISA. CCA tissue microarrays were used to examined for HER2, PD-L1, and FGFR2 expression. Logistic regression was used to investigate an association between factors and IgG. Cox regression was used to determine factors that affected CCA patient survival. RESULTS: IgG for OV were positive in 162 cases, and the prevalence was 73.3% (95% CI=68.0-78.7). About three quarters (78.3%) had large duct type tumors and concomitant intraductal papillary neoplasm of bile ducts (IPNB) occurred in 92 (50%) cases. HER2 expression was positive in 94 (61.4%) cases. Positive PD-L1 and FGFR2 expression occurred in 125 (83.9%) and 100 (67.1%) cases. IgG for OV had no significant correlation to any histological feature but had significant correlation with HER2 overexpression with adjusted OR=2.32 (95% CI=1.09-4.96, P=0.03). Cases of CCA with OV IgG positive had a significantly poor prognosis with adjusted HR=1.66 (95% CI=1.13-2.43, P=0.01). CONCLUSION: We found a high prevalence of serum IgG for OV-positive CCA patients and a correlation with overexpression of HER2. Moreover, IgG for OV and HER2 expression indicated poor survival of CCA. Therefore, future clinical studies for anti-HER2 treatments should focus on OV-associated CCA.

In vitro and in vivo Anti-Tumor Effects of Pan-HER Inhibitor Varlitinib on Cholangiocarcinoma Cell Lines.

BACKGROUND: Cholangiocarcinoma (CCA) is a slowly progressing but highly aggressive malignancy. Targeting the HER protein family represents a potential therapeutic strategy for CCA treatment. The pan-HER inhibitor varlitinib is being developed for the treatment of breast cancer, gastric cancer, and biliary tract cancer, which includes CCA. This study aims to evaluate the anti-tumor effect of varlitinib on CCA using both in vitro and in vivo models. MATERIALS AND METHODS: HER family expression profiles and the cytotoxic activity of varlitinib were determined in CCA cell lines (KKU-214, KKU-213, KKU-156 and KKU-100) and cholangiocyte (MMNK-1). Anti-proliferation and apoptosis induction were examined in KKU-214 and KKU-100 cell lines. A combination of varlitinib with PI3K inhibitor, BKM-120, was explored for efficacy in the KKU-100 cell line. In addition, the anti-tumor activity of varlitinib on CCA and the key metabolites were evaluated in tumor tissues from CCA xenograft model. RESULTS: Elevated expressions of EGFR and HER2 were observed in KKU-214 and KKU-100 cells and varlitinib can suppress CCA cell growth in the micromolar range. Varlitinib inhibits cell proliferation and enhances cell death via the suppression of Akt and Erk1/2 activity in the KKU-214 cell line. While KKU-100 cells showed a poor response to varlitinib, a combination of varlitinib with BKM-120 improved anti-tumor activity. Varlitinib can significantly suppress tumor growth in the CCA xenograft model after oral administration for 15 days without noticeable toxicity, and aspartate can be the key metabolite to correlate with varlitinib response. CONCLUSION: Our study indicates that varlitinib is a promising therapeutic agent for CCA treatment via the inhibition of EGFR/HER2. The anti-tumor effect of varlitinib on CCA also showed synergism in combination with PI3K inhibition. Aspartate metabolite level was correlated with varlitinib response. Combination of varlitinib with targeted drug or cytotoxic drug was recommended.

Inhibitory effect of NVP-BKM120 on cholangiocarcinoma cell growth.

Abnormal activation of the phosphatidylinositol 3-kinase (PI3K) pathway has been demonstrated in certain types of cancer, including cholangiocarcinoma (CCA). This pathway may therefore be a promising target for CCA treatment. The present study assessed the inhibitory effect of NVP-BKM120, a pan-class I PI3K inhibitor, on CCA cell growth. This inhibitory effect was determined using CCA cell lines and in CCA-inoculated mice. The result from sulforhodamine B (SRB) assay demonstrated that NVP-BKM120 treatment inhibited CCA cell growth in a dose-dependent manner, even at the lowest tested concentration. The in vivo study revealed that oral administration of NVP-BKM120 (10 or 30 mg/kg) to CCA-inoculated nude mice led to a reduction in tumor growth when compared with controls, which was indicated by an immunohistochemical assay for Ki67 expression. In addition, the result from TUNEL assay demonstrated that NVP-BKM120 induced cancer cell death without any signs of toxicity, which indicated by the body weight of mice (data not shown). Western blot analysis demonstrated that NVP-BKM120 inhibited CCA cell growth by suppressing RAC serine/threonine protein kinase/mechanistic target of rapamycin activation and inhibiting the phosphorylation of phosphatase and tensin homolog, which is the inactivation form of the negative regulator of this pathway. Therefore, the results of the present study indicated that NVP-BKM120 should be considered as a therapeutic agent against CCA that could be used to improve treatment.

Protein Kinases as Targets for Opisthorchis viverrini- Associated Cholangiocarcinoma Therapy.

Protein kinases are enzymes that catalyze the transfer of phosphate from ATP to the serine/threonine or tyrosine residues of target molecules. These are key important mediators in a signaling cascade involved in several biological processes. Dysregulation of their activity has been found in various tumors. From the increased understanding of kinase structure and activation mechanisms emerged new strategies for targeting kinase in cancer treatment. Nowadays, kinase specific inhibitors are developed and widely used for clinical cancer treatment. In this review, we focus on protein kinases that are involved in cholangiocarcinoma (CCA). CCA is a slow progression tumor that is recognized as a major public health issue in northeastern Thailand. The standard regimen for CCA treatment is surgical resection. However, the patient's clinical outcome is still problematic. Therefore, the search to identify molecular mechanisms and molecules that are involved in carcinogenesis and the progression of CCA that can be used as therapeutic targets is urgently required. Aberrant expression and activation, as well as the functions of protein kinases in CCA, have been extensively studied in order to apply them as therapeutic targets. This review provides the information on protein kinases and their activity in CCA, as well as the preclinical data on kinase inhibitors that have been evaluated for this cancer.

Inhibition of l-type amino acid transporter 1 activity as a new therapeutic target for cholangiocarcinoma treatment.

Unlike normal cells, cancer cells undergo unlimited growth and multiplication, causing them to require massive amounts of amino acid to support their continuous metabolism. Among the amino acid transporters expressed on the plasma membrane, l-type amino acid transporter-1, a Na+-independent neutral amino acid transporter, is highly expressed in many types of human cancer including cholangiocarcinoma. Our previous study reported that l-type amino acid transporter-1 and its co-functional protein CD98 were highly expressed and implicated in cholangiocarcinoma progression and carcinogenesis. Therefore, this study determined the effect of JPH203, a selective inhibitor of l-type amino acid transporter-1 activity, on cholangiocarcinoma cell inhibition both in vitro and in vivo. JPH203 dramatically suppressed [14C]l-leucine uptake as well as cell growth in cholangiocarcinoma cell lines along with altering the expression of l-type amino acid transporter-1 and CD98 in response to amino acid depletion. We also demonstrated that JPH203 induced both G2/M and G0/G1 cell cycle arrest, as well as reduced the S phase accompanied by altered expression of the proteins in cell cycle progression: cyclin D1, CDK4, and CDK6. There was also cell cycle arrest of the related proteins, P21 and P27, in KKU-055 and KKU-213 cholangiocarcinoma cells. Apoptosis induction, detected by an increase in trypan blue-stained cells along with a cleaved caspase-3/caspase-3 ratio, occurred in JPH203-treated cholangiocarcinoma cells at the highest concentration tested (100 µM). As expected, daily intravenous administration of JPH203 (12.5 and 25 mg/kg) significantly inhibited tumor growth in KKU-213 cholangiocarcinoma cell xenografts in the nude mice model in a dose-dependent manner with no statistically significant change in the animal's body weight and with no differences in the histology and appearance of the internal organs compared with the control group. Our study demonstrates that suppression of l-type amino acid transporter-1 activity using JPH203 might be used as a new therapeutic strategy for cholangiocarcinoma treatment.

Potential of Selenium Compounds as New Anticancer Agents for Cholangiocarcinoma.

We examined the in vitro effects of the selenium compounds sodium selenite (Se) and selenomethionine (SeMet) on cholangiocarcima (CCA) cell growth and migration to determine their potential usefulness as anticancer agents. The effect of both compounds on the selenoprotein M level was investigated, as well as the association between the expression level of selenoprotein M and the patients' clinicopathological data. Se and SeMet inhibited CCA cell growth with half-maximal inhibitory concentration values of 1.7-2.1 µM and 18.8-37.9 µM, respectively. Both compounds increased the ratio of B-cell lymphoma 2 (BCL2) to BCL2-associated X (BAX), triggering apoptotic cell death, and inhibited cell migration by reducing the ratio of N-cadherin to E-cadherin, an epithelial-mesenchymal transition marker. In addition, Se and SeMet increased selenoprotein M protein in CCA cells. Low expression of selenoprotein M in CCA tissues was significantly associated with shorter patient survival. In conclusion, selenium may potentially be an alternative anticancer agent that might lead to a better prognosis in patients with CCA.

Xanthohumol inhibits STAT3 activation pathway leading to growth suppression and apoptosis induction in human cholangiocarcinoma cells.

STAT3 plays a significant role in the development of cholangiocarcinoma (CCA) associated with the liver fluke (Opisthorchis viverrini; Ov). Xanthohumol (XN), a prenylated flavonoid extracted from hops, has known anticancer activity and could potentially target STAT3. The present study determined the effect of XN on STAT3, as well as ascertained its usefulness against CCA. The CCA cell proliferation at 20 µM and 50 µM of XN was shown to inhibited, while 20 µM partially inhibited IL-6-induced STAT3 activation. At 50 µM, the inhibition was complete. The reduction in STAT3 activity at 20 and 50 µM was associated with a significant reduction of CCA cell growth and apoptosis. We also found that the administration of 50 µM XN orally in drinking water to nude mice inoculated with CCA led to a reduction in tumor growth in comparison with controls. In addition, apoptosis of cancer cells increased although there was no visible toxicity. The present study shows that XN can inhibit STAT3 activation both in vivo and in vitro due to suppression of the Akt-NFκB signaling pathway. XN should be considered as a possible therapeutic agent against CCA.

Chloroquine exerts anti-metastatic activities under hypoxic conditions in cholangiocarcinoma cells.

Intra-tumoral hypoxia is an environment that promotes tumor cell migration, angiogenesis and epithelial- mesenchymal transition that accounts for a major mechanism of metastasis. Chloroquine potentially offers a new therapeutic approach with an 'old' drug for effective and safe cancer therapies, as it exerts anti-metastatic activity. We investigated the inhibitory effect of chloroquine on cholangiocarcinoma (CCA) cell migration under cobalt chloride (CoCl2)-stimulated hypoxia. We showed that chloroquine suppressed CCA cell migration under hypoxic-mimicking conditions on exposure to 100 µM CoCl2. Moreover, chloroquine stabilized the protein level of prolyl hydroxylase domain proteins (PHD-2) but reduced the levels of hypoxic responsive proteins such as hypoxia-inducible factor (HIF-1α) and vascular endothelial growth factor (VEGF). It also suppressed epithelial mesenchymal transition (EMT) by increasing the ratio of E-cadherin to N-cadherin under hypoxic conditions. In conclusion, chloroquine can inhibit hypoxia-stimulated metastasis via HIF-1α/VEGF/EMT which may serve as a useful additional strategy for CCA therapy.

STATs profiling reveals predominantly-activated STAT3 in cholangiocarcinoma genesis and progression.

BACKGROUND: We investigated the aberrant expression of the STAT family in humans and liver fluke (Opisthorchis viverrini, Ov)-induced hamster cholangiocarcinoma (CCA) tissues. METHODS: The expression and phosphorylation of STAT1, STAT2, STAT3, STAT4, STAT5a, STAT5b and STAT6 in human hamster CCA tissues were immunohistochemistry-profiled. Localizations of STAT5 in macrophages and lipopolysaccharide (LPS)-induced macrophage-conditioned media mediated STAT3 activation in CCA cells were demonstrated. RESULTS: The expressions of STAT 1-4 and 6 were detected in the cytoplasm of hyperplastic bile ducts and tumor cells, whereas STAT5a and STAT5b were observed in macrophages and connective tissues surrounding tumor, respectively. The expressions of STAT3 and STAT5b were significantly observed in tumors with a poorer histological differentiation. STAT3 expression was significantly associated with shorter survival of CCA patients and was predominately activated in CCA cell lines. In the CCA-hamsters, STATs expression was gradually increased along the carcinogenesis, especially at 30 days post-infection in which the inflammatory response was markedly observed, showing the correlation between the inflammation and STATs activation. Moreover, LPS-induced macrophage-conditioned media could mediate STAT3 activation in CCA cells. CONCLUSIONS: STAT3 is the major STAT, which plays roles in the inflammation that contributes to CCA carcinogenesis and progression and may serve as a marker for a poor prognosis of CCA.

Increased activation of PI3K/AKT signaling pathway is associated with cholangiocarcinoma metastasis and PI3K/mTOR inhibition presents a possible therapeutic strategy.

Phosphatidylinositol 3-kinase (PI3K) signaling plays a critical role in cholangiocarcinoma (CCA), as well as anti-cancer drug resistance and autophagy, the type II program cell death regulation. In this work, we aimed to: (1) determine the expression levels of several key components of PI3K signaling and (2) evaluate whether NVP-BEZ235, a novel dual PI3K/mTOR inhibitor, could inhibit CCA cell growth. Immunohistochemistry for p85α, p110α, AKT, p-AKT (T308), mTOR, p-mTOR (S2448), GSK-3ß, p-GSK-3ß (S9), PTEN, and p-PTEN (S380, T382/383) was performed in 30 CCA patients. Western blotting was used to analyze PTEN and p-PTEN expression in the cell lines (KKU-OCA17, KKU-100, KKU-M055, KKU-M139, KKU-M156, KKU-M213, and KKU-M214). The effects of NVP-BEZ235 on CCA cells were evaluated using a growth inhibition assay, flow cytometer and migration assay. Increased activation of PI3K/AKT signaling was reproducibly observed in the CCA tissues. The expression of p85α, mTOR, and GSK-3ß was significantly correlated with metastasis. Interestingly, PTEN suppression by loss of expression or inactivation by phosphorylation was observed in the majority of patients. Furthermore, NVP-BEZ235 effectively inhibited CCA cell growth and migration through reduced AKT and mTOR phosphorylation and significantly induced G1 arrest without apoptosis induction, although increase autophagy response was observed. In conclusion, the constitutive activation of PI3K/AKT pathway in CCA is mainly due to PTEN inactivation by either loss of expression or phosphorylation along with an increased expression in its pathway components heralding a poor prognosis for CCA patients. This work also indicates that inhibition of PI3K and mTOR activity by the inhibitor NVP-BEZ235 has anti-cancer activity against CCA cells which might be further tested for CCA treatment.

Survey of activated kinase proteins reveals potential targets for cholangiocarcinoma treatment.

Improving therapy for patients with cholangiocarcinoma (CCA) presents a significant challenge. This is made more difficult by a lack of a clear understanding of potential molecular targets, such as deregulated kinases. In this work, we profiled the activated kinases in CCA in order to apply them as the targets for CCA therapy. Human phospho-receptor tyrosine kinases (RTKs) and phospho-kinase array analyses revealed that multiple kinases are activated in both CCA cell lines and human CCA tissues that included cell growth, apoptosis, cell to cell interaction, movement, and angiogenesis RTKs. Predominately, the kinases activated downstream were those in the PI3K/Akt, Ras/MAPK, JAK/STAT, and Wnt/ß-catenin signaling pathways. Western blot analysis confirms that Erk1/2 and Akt activation were increased in CCA tissues when compared with their normal adjacent tissue. The inhibition of kinase activation using multi-targeted kinase inhibitors, sorafenib and sunitinib led to significant cell growth inhibition and apoptosis induction via suppression of Erk1/2 and Akt activation, whereas drugs with specificity to a single kinase showed less potency. In conclusion, our study reveals the involvement of multiple kinase proteins in CCA growth that might serve as therapeutic targets for combined kinase inhibition.

Cytokines released from activated human macrophages induce epithelial mesenchymal transition markers of cholangiocarcinoma cells.

Stromal-epithelial interactions are important for carcinogenesis. Once cancerous lesions develop, a chronically inflamed tumor microenvironment promotes migration and invasion of tumor cells. Multiple immune cell populations are involved in inflammatory processes, including tumor-associated macrophages (TAMs) which have been proposed as major contributors to tumor progression. The epithelial-mesenchymal transition (EMT) is a process in which epithelial cells trans-differentiate and acquire an invasive mesenchymal phenotype. As EMT represents a crucial step in disease progression, it is important to investigate the mechanisms regulating this step. We aimed to identify the profiles of cytokines produced by activated human macrophages and to demonstrate effects on the expression of EMT-related genes in human cholangiocarcinoma (CCA) cell lines. Our results showed that LPS-activated macrophages produced and secreted IL4, IL6, IL10, TNF-α and TGF-ß1. After addition of macrophage conditioning media to CCA cells, expression of epithelial markers E-cadherin and CK-19 was significantly reduced, whereas the expression of mesenchymal markers, S100A4 and MMP9 was strongly induced. Taken together, various cytokines secreted by activated macrophages could induce EMT by altering the expression of EMT-related genes in CCA.