Epigenetic regulation in the carcinogenesis of cholangiocarcinoma

Overexpression of KMT9α is associated with poor outcome in cholangiocarcinoma patients

PURPOSE

The newly discovered histone methyltransferase KMT9 serves as an epigenetic regulator of carcinogenesis in various cancer entities. For the first time, we investigated the presence of KMT9α in cholangiocarcinoma, the association with histologic subtypes, and its impact on survival.

METHODS

A tissue microarray cohort of all CCA patients who underwent surgical resection with curative intent between 08/2005 and 12/2021 at the University Hospital Frankfurt was immunohistochemically analyzed with the KMT9α antibody. For overall survival, Kaplan-Meier curves and Cox-regression analyses were performed.

RESULTS

In total, 174 patients were suitable for IHC analysis. Of the patients, 35.1% (n = 61) overexpressed KMT9α. Kaplan-Meier curves revealed a median OS of 34.75 months (95% CI = 20.23-49.27 months) for all CCA patients positive for KMT9α in comparison to 54.21 months (95% CI = 41.78-66.63 months) for patients lacking KMT9α overexpression (p = 0.004). Subtype analysis revealed strong differences in KMT9α expression. Multivariate Cox regression analysis identified KMT9α as an independent risk factor for shorter OS in CCA.

CONCLUSION

This study demonstrates that a marked subset of CCA patients exhibit overexpression of KMT9α. These findings underscore the prognostic significance of KMT9α and reinforce its potential as a therapeutic target, consistent with its role in other cancer types.

The roles of epigenetic regulation in cholangiocarcinogenesis

Cholangiocarcinoma (CCA), a heterogeneous malignancy of bile duct epithelial cells, is characterized by aggressiveness, difficult diagnosis, and poor prognosis due to limited understanding and lack of effective therapeutic strategies. Genetic and epigenetic alterations accumulated in CCA cells can cause the aberrant regulation of oncogenes and tumor suppressors. Epigenetic alterations with histone modification, DNA methylation, and noncoding RNA modulation are associated with the carcinogenesis of CCA. Mutation or silencing of genes by various mechanisms can be a frequent event during CCA development. Alterations in histone acetylation/deacetylation at the posttranslational level, DNA methylation at promoters, and noncoding RNA regulation contribute to the heterogeneity of CCA and drive tumor development. In this review article, we mainly focus on the roles of epigenetic regulation in cholangiocarcinogenesis. Alterations in epigenetic modification can be potential targets for the therapeutic management of CCA, and epigenetic targets may become diagnostic biomarkers of CCA.

The molecular mechanisms and targeting strategies of transcription factors in cholangiocarcinoma

INTRODUCTION

Cholangiocarcinoma consists of a cluster of malignant biliary tumors that tend to have a poor prognosis, ranking as the second most prevalent type of liver cancer, and their incidence rate has increased globally recently. The high-frequency driving mutations of cholangiocarcinoma, such as KRAS/IDH1/ARID1A/P53, imply the epigenetic instability of cholangiocarcinoma, leading to the dysregulation of various related transcription factors, thus affecting the occurrence and development of cholangiocarcinoma. Increasingly evidence indicates that the high heterogeneity and malignancy of cholangiocarcinoma are closely related to the dysregulation of transcription factors which promote cell proliferation, invasion, migration, angiogenesis, and drug resistance through reprogrammed transcriptional networks. It is of great significance to further explore and summarize the role of transcription factors in cholangiocarcinoma.

AREAS COVERED

This review summarizes the oncogenic or tumor suppressive roles of key transcription factors in regulating cholangiocarcinoma progression and the potential targeting strategies of transcription factors in cholangiocarcinoma.

EXPERT OPINION

Cholangiocarcinoma is a type of cancer highly influenced by transcriptional regulation, specifically transcription factors and epigenetic regulatory factors. Targeting transcription factors could be a potential and important strategy that is likely to impact future cholangiocarcinoma treatment.

Liquid biopsy in cholangiocarcinoma: Current status and future perspectives

Cholangiocarcinoma (CCA) are a heterogeneous group of tumors in terms of aetiology, natural history, morphological subtypes, molecular alterations and management, but all sharing complex diagnosis, management, and poor prognosis. Several mutated genes and epigenetic changes have been detected in CCA, with the potential to identify diagnostic and prognostic biomarkers and therapeutic targets. Accessing tumoral components and genetic material is therefore crucial for the diagnosis, management and selection of targeted therapies; but sampling tumor tissue, when possible, is often risky and difficult to be repeated at different time points. Liquid biopsy (LB) represents a way to overcome these issues and comprises a diverse group of methodologies centering around detection of tumor biomarkers from fluid samples. Compared to the traditional tissue sampling methods LB is less invasive and can be serially repeated, allowing a real-time monitoring of the tumor genetic profile or the response to therapy. In this review, we analysis the current evidence on the possible roles of LB (circulating DNA, circulating RNA, exosomes, cytokines) in the diagnosis and management of patients affected by CCA.

The long noncoding RNA DLGAP1-AS2 facilitates cholangiocarcinoma progression via miR-505 and GALNT10

Cholangiocarcinoma (CCA) is a highly invasive malignant tumor with high mortality. Most cases of CCA are already advanced when they are detected, resulting in poor prognosis. As such, there is an ongoing need for the identification of effective biomarkers for CCA. The long noncoding RNA DLGAP1-AS2 has been reported to have prognostic value in glioma and Wilms' tumor. Here, we investigated the function of DLGAP1-AS2 in CCA. The differential expression of DLGAP1-AS2 in CCA tissues and normal tissues was first examined using data from the The Cancer Genome Atlas database and then in CCA cell lines by quantitative RT-PCR (qRT-PCR). The target gene was predicted by bioinformatics analysis, and the binding sites were confirmed using luciferase assay. DLGAP1-AS2 is up-regulated in CCA, and high DLGAP1-AS2 expression promotes cell viability and is associated with poor prognosis. Notably, DLGAP1-AS2 acts as a sponge to suppress miR-505 expression, and miR-505 reduces the expression of N-acetylgalactosaminyltransferase 10 (GALNT10) in CCA cells. Biofunctional experiments revealed that a miR-505 inhibitor almost completely removed the inhibitory effect of si-DLGAP1-AS2 on CCA cell malignant progression, whereas the malignant phenotype of cells cotransfected with si-DLGAP1-AS2 and si-GALNT10 was significantly reduced as compared with the control. In summary, the DLGAP1-AS2/miR-505/GALNT10 axis may contribute to regulating the malignant progression of CCA and may have potential as a novel target for CCA therapy.

Impact of Wortmannilactone F and G31P on Clonorchis Sinensis-infected mice

Clonorchis sinensis could induce inflammation, epithelial hyperplasia and fibrosis in the intrahepatic bile duct as a food-borne parasite, which was associated with the development of cholangiocarcinoma (CCA). Praziquantel was the most effective drug on treatment of this kind of parasite. However, new drugs with minimal toxicity to the host were urgently needed due to the side effects of Praziquantel and its CCA risk. In this study, helminth mitochondria respiratory chain blocker Wortmannilatone F (WF) and IL-8 analogue CXCL8 (3-72) K11R/G31P were used to treat BALB/C mice infected by Clonorchis sinensis. We investigated the gross and histopathological morphology of the liver, inflammation-associated cytokine IL-6, lipid peroxidation-related proteins cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX), collagen fiber accumulation and fibroblast-specific protein 1 (FSP1), malignant markers proliferating cell nuclear antigen (PCNA) and cytokeratin 19 (CK19), as well as the disinfection effect on these parasites in vitro. WF inhibited and killed the worms dramatically, and the combination of WF with G31P improved the condition of the hepatobiliary duct tissue greatly. These outcomes indicated that the combination of WF and G31P was a potential therapeutic method to treat the Clonorchis sinensis infection.

Cholangiocarcinoma: Classification, Histopathology and Molecular Carcinogenesis

Cholangiocarcinoma (CC) is the second most common tumor of the liver, originating from the biliary system with increasing incidence and mortality worldwide. Several new classifications review the significance of tumor localization, site of origin, proliferation and biomarkers in the intrahepatic, perihilar and distal forms of the lesion. Based on growth pattern mass-forming, periductal-infiltrating, intraductal, undefined and mixed types are differentiated. There are further subclassifications which are applied for the histological features, in particular for intrahepatic CC. Recognition of the precursors and early lesions of CC including biliary intraepithelial neoplasia (BilIN), intraductal papillary neoplasm of the bile ducts (IPNB), biliary mucinous cystic neoplasm (MCNB) and the candidate precursors, such as bile duct adenoma and von Meyenburg complex is of increasing significance. In addition to the previously used biliary markers detected by immunohistochemistry, several new markers have been added to the differentiation of both the benign and malignant lesions, which can be used to aid in the subclassification in association with the outcome of CC. Major aspects of biliary carcinogenesis have been revealed, yet, the exact way of this diverse process is still unclear. The factors contributing to molecular cholangiocarcinogenesis include various risk factors, different anatomical localizations, multiple cellular origins, genetic and epigenetic alterations, tumor microenvironment, heterogeneity and clonal evolution. Driver mutations have been identified, implying that they are optimal candidates for targeted therapy. The most promising therapeutic candidates have entered clinical trials.

Mutation of Isocitrate Dehydrogenase 1 in Cholangiocarcinoma Impairs Tumor Progression by Inhibiting Isocitrate Metabolism

Aim: Isocitrate dehydrogenase 1 (IDH1) is key enzyme involved in cellular metabolism and DNA repair. Mutations in IDH1 occur in up to 25% of cholangiocarcinomas. The present study aimed to explore the features of cellosaurus REB cells with mutant and wide-type IDH1. Methods: To compare the features of IDH1 knockout and mutation in cholangiocarcinoma, we firstly constructed the IDH1 knockout and IDH1 mutation cell lines. We then evaluated the viability of these cell lines using the cell count assay and MTT assay. Next, we determined cell migration and invasion using the Transwell assay. Additionally, to evaluate the effects of IDH1 on cellular metabolism, the levels of α-ketoglutarate (α-KG) and nicotinamide adenine dinucleotide phosphate (NADPH) were determined using enzyme-linked immunosorbent assay. We then applied ChIPbase dataset to explore the genes that were regulated by IDH1. Results: High frequency of mutated IDH1 was observed in the cholangiocarcinoma and IDH1 R132C was presented in more than 80% of mutations. The results showed that IDH1 knockout decreased cell proliferation, migration and invasion, whereas the overexpression of IDH1 in IDH1 knockout cell line recovered its proliferation, migration and invasion capacities. Additionally, IDH1 mutation reduced the levels of NADPH and α-KG. Furthermore, investigation into the underlying mechanisms revealed that IDH1 overexpression induced the expression of aldehyde dehydrogenase 1 thereby promoting cell proliferation, migration and invasion. Conclusion:IDH1 plays an important role in cholangiocarcinoma and its mutation impairs tumor progression in part by inhibition of isocitrate metabolism.

The protein kinase CK2 contributes to the malignant phenotype of cholangiocarcinoma cells

Cholangiocarcinoma (CCA) is a particularly aggressive hepatobiliary malignancy, for which the molecular mechanisms underlying the malignant phenotype are still poorly understood, and novel and effective therapeutic strategies are limited. The pro-survival protein kinase CK2 is frequently overexpressed in cancer and is receiving increasing interest as an anti-tumor drug target. Its precise role in CCA biology is still largely unknown. Here we show that expression of the CK2α and α' catalytic subunits and of the β regulatory subunit is increased in human CCA samples. Increased expression of CK2 subunits was shown in CCA cell lines compared to non-transformed cholangiocytes. We used chemical inhibition of CK2 and genetic modification by CRISPR/Cas9 to explore the contribution of CK2 to the malignant phenotype of CCA cells. Disruption of CK2 activity results in cell death through apoptosis, reduced invasion and migration potential, and G0/G1 cell cycle arrest. Importantly, CCA cells with a reduced CK2 activity are more sensitive to chemotherapy. Altogether, our results demonstrate that CK2 significantly contributes to increased proliferative potential and augmented growth of CCA cells and indicate the rationale for its targeting as a promising pharmacologic strategy for cholangiocarcinoma.

Overexpression of polycomb repressive complex 2 key components EZH2/SUZ12/EED as an unfavorable prognostic marker in cholangiocarcinoma

BACKGROUND

Cholangiocarcinoma (CCA) is a fatal liver cancer arising from bile duct epithelium. Polycomb repressive complex 2 (PRC2) is a histone methyltransferase enzyme that catalyzes trimethylation of histone H3 on lysine 27, resulting transcriptional gene silencing. The key components of PRC2 are EZH2, SUZ12 and EED, which EZH2 is a catalytic subunit. The defect of individual PRC2 components has been shown to enhance carcinogenesis and cancer progression. The aim of this study was to determine the expression of individual PRC2 components and evaluate its association with clinicopathological data in CCA patients.

METHODS

The expression of PRC2 components including EZH2, SUZ12 and EED was determined by immunohistochemistry in 40 CCA tissue samples.

RESULTS

The expression of EZH2 and SUZ12 in CCA tissue was significantly higher than that in adjacent non-cancerous tissue (P < 0.001). The high cytoplasmic EZH2 expression was significantly associated with short overall survival in CCA (P = 0.030). Interestingly, a combined high nuclear and cytoplasmic expression of EZH2 was found to be a worse prognostic marker for overall survival (P = 0.015). Moreover, combined high expression of EZH2 and SUZ12/EED was also associated with short overall survival (P < 0.05).

CONCLUSIONS

Our findings suggest that overexpression of the PRC2 key components especially EZH2 in both nucleus and cytoplasm can be potentially used as a prognostic marker for CCA.

Opisthorchiasis-Induced Cholangiocarcinoma: How Innate Immunity May Cause Cancer

Innate, inflammatory responses towards persistent Opisthorchis viverrini (OV) infection are likely to contribute to the development of cholangiocarcinoma (CCA), a liver cancer that is rare in the West but prevalent in Greater Mekong Subregion countries in Southeast Asia. Infection results in the infiltration of innate immune cells into the bile ducts and subsequent activation of inflammatory immune responses that fail to clear OV but instead may damage local tissues within the bile ducts. Not all patients infected with OV develop CCA, and so tumourigenesis may be dependent on multiple factors including the magnitude of the inflammatory response that is activated in infected individuals. The purpose of this review is to summarize how innate immune responses may promote tumourigenesis following OV infection and if such responses can be used to predict CCA onset in OV-infected individuals. It also hypothesizes on the role that Helicobacterspp., which are associated with liver fluke infections, may play in activation of the innate the immune system to promote tissue damage and persistent inflammation leading to CCA.

Genomic Profiling of Biliary Tract Cancers and Implications for Clinical Practice

OPINION STATEMENT

Biliary tract cancers are relatively uncommon, have an aggressive disease course and a dismal clinical outcome. Until recently, there have been very few clinical advances in the management of these patients and gemcitabine-based chemotherapy has been the only widely accepted systemic therapy. The advent of next generation sequencing technologies can potentially change the treatment paradigm of this disease. Targeted therapy directed against actionable mutations and identification of molecular subsets with distinct prognostic significance is now feasible in clinical practice. Mutation profiling has highlighted the genomic differences between the intra, extrahepatic cholangiocarcinoma, and gallbladder cancer. The mutational spectrum of intrahepatic cholangiocarcinoma differs according to geographic location and ethnicity. There is a higher incidence of chromatin modulating gene mutations in Western patients as compared with Asian patients with liver fluke-associated cholangiocarcinoma. KRAS and p53 mutations are associated with an aggressive disease prognosis while FGFR mutations may signify a relatively indolent disease course of intrahepatic cholangiocarcinoma. FGFR and IDH mutations have promising agents in clinical trials at this time. An estimated 15 % of gallbladder cancers have Her2/neu amplification and can be targeted by trastuzumab. On the other hand, an estimated 10-15 % of cholangiocarcinomas have DNA repair mutations and may be candidates for immune therapies with checkpoint inhibitors. The promise of targeted therapies for biliary tract cancers can be fulfilled with well-designed, prospective, and multi-center clinical trials.

Whole-exome tumor sequencing study in biliary cancer patients with a response to MEK inhibitors

We previously conducted a phase-II study with selumetinib (AZD6244), a small molecule inhibitor of MEK1/2, in advanced biliary tract cancers (BTC), where the primary endpoint was response rate. Several patients experienced objective response. These findings were confirmed with MEK162 in a similar patient population. To assess for tumor-specific genetic variants that mediate sensitivity to MEK inhibition in BTC, we performed whole-exome sequencing in patients with an objective response to selumetinib. Normal and tumor DNA from FFPE tissue from two patients who experienced an objective response underwent whole-exome sequencing. Raw sequence reads were processed with GATK workflow and tumor specific variants were identified using MuTect and VarScan2. Ensemble Variant Effect Predictor was used to determine functional consequences of these variants. Copy number changes and potential gene fusion events were also screened. Findings were compared to assess for any commonality between the two tumor samples, and whether the identified variants were intrinsic to the MAPK pathway. 1169 and 628 tumor-specific variants were identified in the two samples. Further analysis demonstrated 60 and 53 functional and novel variants, respectively. Of the identified tumor-specific variants, fusion events or copy number changes, no commonality was seen. Several variants in genes associated with ERK signaling were present in each tumor sample. Although there were no common tumor-specific variants in the two patients who exhibited an objective response to selumetinib, several genes associated with ERK signaling were identified. Confirmatory studies investigating the role of the identified genes and other potential tumor independent factors need further investigation.

Molecular profiling of biliary tract cancer: a target rich disease

Biliary tract cancers (BTCs) are relatively uncommon orphan tumors that have an aggressive disease course and a poor clinical outcome. Surgery is the only curative treatment, but most patients present with advanced disease and therefore have a limited survival. Gemcitabine and cisplatin based chemotherapy has been the only widely accepted standard systemic therapy regimen in these patients but these tumors can be chemoresistant, further complicating their management. In recent times, there has been considerable research in the genetics of BTC and with the advent of new, advanced technologies like next-generation sequencing (NGS) we are achieving a greater understanding of its disease biology. With the help of NGS, we have now been able to identify actionable mutations such as in the isocitrate dehydrogenase 1 (IDH1), FGFR2, BRAF and HER2/neu genes for targeted therapeutics and correlate the genetic variations with distinct clinical prognoses. This recent genetic information has the potential to make precision medicine a part of routine clinical practice for the management of BTC patients.

Effect of Mir-122 on Human Cholangiocarcinoma Proliferation, Invasion, and Apoptosis Through P53 Expression

Background

Bile duct carcinoma is a common digestive tract tumor with high morbidity and mortality. As a kind of important non-coding RNA, microRNA (miR) plays an important role in post-transcriptional regulation. MiR-122 is the most abundant miR in the liver. Multiple studies have shown that miR-122 level is reduced in a variety of liver tumors and can be used as a specific marker for liver injury. P53 is a classic tumor suppressor gene that can induce tumor cell apoptosis through various pathways. Whether miR-122 affects p53 in bile duct carcinoma still needs investigation.

Material/Methods

miR inhibitor or mimics was transfected to bile duct carcinoma cells to evaluate its function on proliferation, invasion, apoptosis, and p53 expression.

Results

MiR-122 overexpression reduced cell invasion and migration ability, and inhibited cell apoptosis and p53 expression. Inhibiting miR-122 caused the opposite results.

Conclusions

Upregulating miR-122 can suppress bile duct carcinoma cell proliferation and induce apoptosis. MiR-122 could be used as a target for bile duct carcinoma treatment, which provides a new strategy for cholangiocarcinoma patients.

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.