Chaisiri Wongkham

Exome sequencing of liver fluke-associated cholangiocarcinoma

Opisthorchis viverrini–related cholangiocarcinoma (CCA), a fatal bile duct cancer, is a major public health concern in areas endemic for this parasite. We report here whole-exome sequencing of eight O. viverrini–related tumors and matched normal tissue. We identified and validated 206 somatic mutations in 187 genes using Sanger sequencing and selected 15 genes for mutation prevalence screening in an additional 46 individuals with CCA (cases). In addition to the known cancer-related genes TP53 (mutated in 44.4% of cases), KRAS (16.7%) and SMAD4 (16.7%), we identified somatic mutations in 10 newly implicated genes in 14.8–3.7% of cases. These included inactivating mutations in MLL3 (in 14.8% of cases), ROBO2 (9.3%), RNF43 (9.3%) and PEG3 (5.6%), and activating mutations in the GNAS oncogene (9.3%). These genes have functions that can be broadly grouped into three biological classes: (i) deactivation of histone modifiers, (ii) activation of G protein signaling and (iii) loss of genome stability. This study provides insight into the mutational landscape contributing to O. viverrini–related CCA.

The Opisthorchis viverrini genome provides insights into life in the bile duct

Opisthorchiasis is a neglected, tropical disease caused by the carcinogenic Asian liver fluke, Opisthorchis viverrini. This hepatobiliary disease is linked to malignant cancer (cholangiocarcinoma, CCA) and affects millions of people in Asia. No vaccine is available, and only one drug (praziquantel) is used against the parasite. Little is known about O. viverrini biology and the diseases that it causes. Here we characterize the draft genome (634.5 Mb) and transcriptomes of O. viverrini, elucidate how this fluke survives in the hostile environment within the bile duct and show that metabolic pathways in the parasite are highly adapted to a lipid-rich diet from bile and/or cholangiocytes. We also provide additional evidence that O. viverrini and other flukes secrete proteins that directly modulate host cell proliferation. Our molecular resources now underpin profound explorations of opisthorchiasis/CCA and the design of new interventions.

Altered gene expression in Opisthorchis viverrini‐associated cholangiocarcinoma in hamster model

Cholangiocarcinoma (CCA) induced by liver fluke (Opisthorchis viverrini, Ov) infection is one of the most common and serious disease in northeast Thailand. To elucidate the molecular mechanism of cholangiocarcinogenesis induced by Ov infection, we employed a hamster model of CCA induced by Ov and N‐nitrosodimethylamine and analyzed candidate genes involved in CCA using fluorescence differential display‐PCR. Of 149 differentially amplified bands we identified, the upregulation of 23 transcripts and downregulation of 1 transcript related to CCA hamsters were confirmed by a reverse northern macroarray blot. The upregulated genes include signal transduction protein kinase A regulatory subunit Iα (Prkar1a), myristoylated alanine‐rich protein kinase C substrate, transcriptional factor LIM‐4‐only domain, oxysterol‐binding protein involved in lipid metabolism, splicing regulatory protein 9, ubiquitin conjugating enzyme involved in protein degradation, β tubulin, β actin, and collagen type VI. Quantitative real‐time PCR confirmed that the expression of Prkar1a was significantly higher in CCA and its precursor lesion when compared with normal liver and normal gall bladder epithelia (P < 0.05). Prkar1a expression tended to increase along with the progression of biliary transformation from hyperplasia and precancerous lesions to carcinoma. These findings contribute to our understanding of the processes involved in the molecular carcinogenesis of CCA in order to provide a unique perspective on the development of new chemotherapeutics in future.

Prognostic value of serum MUC5AC mucin in patients with cholangiocarcinoma

The authors recently showed that MUC5AC mucin, which is expressed aberrantly in tumor tissue, is present in significant concentrations in serum from patients with cholangiocarcinoma. Subsequently, determination of serum MUC5AC had high sensitivity and specificity for cholangiocarcinoma. In this study, the possible association between serum MUC5AC mucin and the clinical findings of the patients and their prognostic value were explored.

A novel serum carbohydrate marker on mucin 5AC: Values for diagnostic and prognostic indicators for cholangiocarcinoma

The incidence of cholangiocarcinoma (CCA) is increasing globally. Currently, there is no powerful marker for the diagnosis of CCA, which has led to late diagnosis and poor patient outcome. This study was designed to establish a new monoclonal antibody (MoAb) for detecting a serum marker associated with CCA.

Overexpression of vitamin D receptor indicates a good prognosis for cholangiocarcinoma: implications for therapeutics.

Up‐regulation of vitamin D receptor (VDR) expression has been shown in several tumors and is thought to represent an important endogenous response to tumor progression. The authors aimed to verify the expression of VDR and its clinical significance in histologically proven cholangiocarcinoma (CCA).

Serum MUC5AC mucin as a potential marker for cholangiocarcinoma

Aberrant expression of MUC5AC mucin is obvious in cholangiocarcinoma tissues, however, this mucin has never been detected in the serum. Using immunoblotting marked with antibody vs. MUC5AC core protein, we could detect MUC5AC mucin in the serum of 112 from 179 cholangiocarcinoma patients (62.6% sensitivity), two of the 62 with benign hepatobiliary diseases, six of the 60 with hepato-gastrointestinal cancer, and none in either the 60 active opisthorchiasis or 74 healthy persons. Detection of serum mucin in the serum of cholangiocarcinoma patients corresponded well to the MUC5AC expressed in individual tissues. Serum MUC5AC may be used to enhance the diagnostic accuracy of cholangiocarcinoma.

Inflammation-related DNA damage and expression of CD133 and Oct3/4 in cholangiocarcinoma patients with poor prognosis

Nitrative and oxidative DNA damage plays an important role in inflammation-related carcinogenesis. Chronic inflammation such as parasite infection and primary sclerosing cholangitis can be an etiological factor of cholangiocarcinoma. Using a proteomic approach and double-fluorescent staining, we identified high expression and colocalization of albumin and cytokeratin-19 in liver fluke-associated cholangiocarcinoma tissues, compared with normal livers from cholangiocarcinoma patients and cadaveric donors, respectively. Albumin was detected not only in cells of hyperplastic bile ducts and cholangiocarcinoma, but also in liver stem/progenitor cell origin, such as canal of Hering, ductules, and ductular reactions, suggesting the involvement of stem/progenitor cells in cholangiocarcinoma development. To clarify the involvement of liver stem/progenitor cells in cholangiocarcinoma, we examined several stem/progenitor cell markers (CD133, CD44, OV6, and Oct3/4) in cholangiocarcinoma tissues analyzed by immunohistochemical staining, and measured 8-oxodG levels by using HPLC-ECD as an inflammation-related DNA lesion. In addition, a stem/progenitor cell factor Bmi1, 8-nitroguanine (formed during nitrative DNA damage), DNA damage response (DDR) proteins (phosphorylated ATM and γ-H2AX), and manganese-SOD (Mn-SOD) were analyzed by immunohistochemistry. Stem/progenitor cell markers (CD133, OV6, CD44, and Oct3/4) were positively stained in 56, 38, 47, and 56% of 34 cholangiocarcinoma cases, respectively. Quantitative analysis of 8-oxodG revealed significantly increased levels in CD133- and/or Oct3/4-positive tumor tissues compared to negative tumor tissues, as well as 8-nitroguanine formation detected by immunohistochemistry. In the cases of CD44- and/or OV6-positive tissue, no significant difference was observed. Cholangiocarcinoma patients with CD133- and/or Oct3/4-positive tumor tissues showed significantly lower expression of Mn-SOD and higher DDR protein, γ-H2AX. Moreover, CD133- and/or Oct3/4-positive cholangiocarcinoma patients had significant associations with tumor histology types, tumor stage, and poor prognoses. Our results suggest that CD133 and Oct3/4 in cholangiocarcinoma are associated with increased formation of DNA lesions and the DDR protein, which may be involved in genetic instability and lead to cholangiocarcinoma development with aggressive clinical features.

Inflammation-induced protein carbonylation contributes to poor prognosis for cholangiocarcinoma

Carbonylation is an irreversible and irreparable protein modification induced by oxidative stress. Cholangiocarcinoma (CCA) is associated with chronic inflammation caused by liver fluke infection. To investigate the relationship between protein carbonylation and CCA progression, carbonylated proteins were detected by 2D OxyBlot and identified by MALDI-TOF/TOF analyses in pooled CCA tissues in comparison to adjacent nontumor tissues and normal liver tissues. We identified 14 highly carbonylated proteins in CCA tissues. Immunoprecipitation and Western blot analyses of individual samples confirmed significantly greater carbonylation of serotransferrin, heat shock protein 70-kDa protein 1 (HSP70.1), and α1-antitrypsin (A1AT) in tumor tissues compared to normal tissues. The oxidative modification of these proteins was significantly associated with poor prognoses as determined by the Kaplan-Meier method. LC-MALDI-TOF/TOF mass spectrometry identified R50, K327, and P357 as carbonylated sites in serotransferrin, HSP70.1, and A1AT, respectively. Moreover, iron accumulation was significantly higher in CCA tissues with, compared to those without, carbonylated serotransferrin. We conclude that carbonylated serotransferrin-associated iron accumulation may induce oxidative stress via the Fenton reaction, and the carbonylation of HSP70.1 with antioxidative property and A1AT with protease inhibitory capacity may cause them to become dysfunctional, leading to CCA progression.

Decreased expression of galectin-3 is associated with metastatic potential of liver fluke-associated cholangiocarcinoma.

Galectin-3, a beta-galactoside-binding lectin, is a multifunctional protein implicated in a variety of biological functions, including tumour cell adhesion, proliferation, differentiation, cancer progression and metastasis. The present study was performed to clarify the impact of galectin-3 expression on patients with liver fluke-associated cholangiocarcinoma. Galectin-3 expression was examined immunohistochemically in 53 patients with intrahepatic cholangiocarcinoma, who had undergone surgery without pre-operative therapy. All bile duct epithelium expressed galectin-3 with different intensities, according to the different histological subtypes. The poorly-differentiated type expressed galectin-3 less intensely than the papillary, well- to moderately-differentiated types (P=0.012). We observed the association of low galectin-3 expression with lymphatic invasion (P=0.002). Suppression of galectin-3 expression in two human cholangiocarcinoma cell lines using siRNA targeted to galectin-3 significantly increased cell migration and invasion without alterations in cell proliferation. Regulation of galectin-3 expression may therefore be an alternative therapeutic approach to control metastasis of cholangiocarcinoma.