Mapping of population disparities in the cholangiocarcinoma urinary metabolome.

Phenotypic diversity in urinary metabolomes of different geographical populations has been recognized recently. In this study, urinary metabolic signatures from Western (United Kingdom) and South-East Asian (Thai) cholangiocarcinoma patients were characterized to understand spectral variability due to host carcinogenic processes and/or exogenous differences (nutritional, environmental and pharmaceutical). Urinary liquid chromatography mass spectroscopy (LC-MS) spectral profiles from Thai (healthy = 20 and cholangiocarcinoma = 14) and UK cohorts (healthy = 22 and cholangiocarcinoma = 10) were obtained and modelled using chemometric data analysis. Healthy metabolome disparities between the two distinct populations were primarily related to differences in dietary practices and body composition. Metabolites excreted due to drug treatment were dominant in urine specimens from cholangiocarcinoma patients, particularly in Western individuals. Urine from participants with sporadic (UK) cholangiocarcinoma contained greater levels of a nucleotide metabolite (uridine/pseudouridine). Higher relative concentrations of 7-methylguanine were observed in urine specimens from Thai cholangiocarcinoma patients. The urinary excretion of hippurate and methyladenine (gut microbial-host co-metabolites) showed a similar pattern of lower levels in patients with malignant biliary tumours from both countries. Intrinsic (body weight and body composition) and extrinsic (xenobiotic metabolism) factors were the main causes of disparities between the two populations. Regardless of the underlying aetiology, biological perturbations associated with cholangiocarcinoma urine metabolome signatures appeared to be influenced by gut microbial community metabolism. Dysregulation in nucleotide metabolism was associated with sporadic cholangiocarcinoma, possibly indicating differences in mitochondrial energy production pathways between cholangiocarcinoma tumour subtypes. Mapping population-specific metabolic disparities may aid in interpretation of disease processes and identification of candidate biomarkers.

Characterisation of the Serum Metabolic Signature of Cholangiocarcinoma in a United Kingdom Cohort.

BACKGROUND: A distinct serum metabonomic pattern has been previously revealed to be associated with various forms of liver disease. Here, we aimed to apply mass spectrometry to obtain serum metabolomic profiles from individuals with cholangiocarcinoma and benign hepatobiliary diseases to gain an insight into pathogenesis and search for potential early-disease biomarkers. METHODS: Serum samples were profiled using a hydrophilic interaction liquid chromatography platform, coupled to a mass spectrometer. A total of 47 serum specimens from 8 cholangiocarcinoma cases, 20 healthy controls, 8 benign disease controls (bile duct strictures) and 11 patients with hepatocellular carcinoma (as malignant disease controls) were included. Data analysis was performed using univariate and multivariate statistics. RESULTS: The serum metabolome disparities between the metabolite profiles from healthy controls and patients with hepatobiliary disease were predominantly related to changes in lipid and lipid-derived compounds (phospholipids, bile acids and steroids) and amino acid metabolites (phenylalanine). A metabolic pattern indicative of inflammatory response due to cirrhosis and cholestasis was associated with the disease groups. The abundance of phospholipid metabolites was altered in individuals with liver disease, particularly cholangiocarcinoma, but no significant difference was seen between profiles from patients with benign biliary strictures and cholangiocarcinoma. CONCLUSION: The serum metabolome in cholangiocarcinoma exhibited changes in metabolites related to inflammation, altered energy production and phospholipid metabolism. This study serves to highlight future avenues for biomarker research in large-scale studies.

Polymorphisms in Natural Killer Cell Receptor Protein 2D (NKG2D) as a Risk Factor for Cholangiocarcinoma.

BACKGROUND AND AIMS: Understanding of the significant genetic risk factors for Cholangiocarcinoma (CC) remains limited. Polymorphisms in the natural killer cell receptor G2D (NKG2D) gene have been shown to increase risk of CC transformation in patients with Primary Sclerosing Cholangitis (PSC). We present a validation study of NKG2D polymorphisms in CC patients without PSC. METHODS: Seven common Single Nucleotide Polymorphisms (SNPs) of the NKG2D gene were genotyped in 164 non-PSC related CC subjects and 257 controls with HaploView. The two SNPs that were positively identified in the previous Scandinavian study, rs11053781 and rs2617167, were included. RESULTS: The seven genotyped SNPs were not associated with risk of CC. Furthermore, haplotype analysis revealed that there was no evidence to suggest that any haplotype differs in frequency between cases and controls (P > 0.1). CONCLUSION: The common genetic variation in NKG2D does not correlate significantly with sporadic CC risk. This is in contrast to the previous positive findings in the Scandinavian study with PSC-patients. The failure to reproduce the association may reflect an important difference between the pathogenesis of sporadic CC and that of PSC-related CC. Given that genetic susceptibility is likely to be multifaceted and complex, further validation studies that include both sporadic and PSC-related CC are required.

Urinary Metabotyping of Hepatocellular Carcinoma in a UK Cohort Using Proton Nuclear Magnetic Resonance Spectroscopy.

BACKGROUND: Discriminatory metabolic profiles have been described in urinary 1H nuclear magnetic resonance (NMR) spectroscopy studies of African patients with hepatocellular carcinoma (HCC). This study aimed to assess similarities in a UK cohort, where there is a greater etiological diversity. METHODS: Urine from cirrhosis and HCC patients was analyzed using a 600 MHz 1H NMR system. Multivariate analysis and median group MR spectra comparison identified metabolite alterations between groups. Metabolite identification was achieved through literature reference and statistical total correlation spectroscopy. Diagnostic accuracy was compared to serum alpha-fetoprotein (AFP). RESULTS: Of the 52 patients recruited, 13 samples from HCC and 25 from cirrhosis patients were selected. At 200 IU mL-1, diagnostic sensitivity of AFP was 27%. Multivariate analysis of urinary spectra generated diagnostic models with a sensitivity/specificity of 53.6%/96%. p-Cresol sulfate (P = 0.04), creatinine (P = 0.03), citrate (P = 0.21) and hippurate (P = 0.52) were reduced in the HCC patients. Carnitine (P = 0.31) and formate (P = 0.44) were elevated. CONCLUSION: Diagnostic sensitivity was lower than previous African studies, but still outperformed serum AFP. Reduced creatinine, citrate and hippurate and elevated carnitine are comparable with the African studies. p-Cresol sulfate alteration is a novel finding and may indicate an altered sulfonation capacity of the liver in patients with HCC.

The challenge of cholangiocarcinoma: dissecting the molecular mechanisms of an insidious cancer.

Cholangiocarcinoma is a fatal cancer of the biliary epithelium and has an incidence that is increasing worldwide. Survival beyond a year of diagnosis is less than 5%, and therapeutic options are few. Known risk factors include biliary diseases such as primary sclerosing cholangitis and parasitic infestation of the biliary tree, but most cases are not associated with any of these underlying diseases. Numerous in vitro and in vivo models, as well as novel analytical techniques for human samples, are helping to delineate the many pathways implicated in this disease, albeit at a frustratingly slow pace. As yet, however, none of these studies has been translated into improved patient outcome and, overall, the pathophysiology of cholangiocarcinoma is still poorly understood. There remains an urgent need for new approaches and models to improve management of this insidious and devastating disease. In this review, we take a bedside-to-bench approach to discussing cholangiocarcinoma and outline research opportunities for the future in this field.

Clinical outcomes, quality of life, advantages and disadvantages of metal stent placement in the upper gastrointestinal tract.

PURPOSE OF REVIEW: This review will discuss the immediate- and long-term success, complications and overall benefits of self-expandable metal stents (SEMSs) in malignant or benign obstruction of the oesophagus, stomach and duodenum. Over recent years, indications such as benign disease have expanded, as has SEMS diversity with self-expandable plastic stents (SEPSs) or fully covered and biodegradable stents, for example. RECENT FINDINGS: SEMSs have been increasingly used in malignant upper gastrointestinal obstruction with many reports confirming efficacy, despite a significant complication rate. Fully covered stents are increasingly used for a variety of benign oesophageal disease, but their place in gastric outlet obstruction is still unclear. Covered and uncovered stents have different functional characteristics and stent type must be selected on an individual basis. Biodegradable stents show promise and the outcome of experience in larger patient cohorts is eagerly awaited. SUMMARY: This area is an evolving field, in which the clinician requires up-to-date knowledge of therapeutic options to make individualized treatment choices in difficult clinical circumstances. Technical and clinical success for oesophageal or gastroduodenal SEMSs are then above 90%. Minor complications are common, but serious complications seldom occur. Biodegradable stents may be useful, especially when stenting is needed for a short period of time.

Elevated levels of neutrophil gelatinase-associated lipocalin in bile from patients with malignant pancreatobiliary disease.

OBJECTIVES: Accurate differentiation between benign and malignant causes of biliary obstruction remains challenging and reliable biomarkers are urgently needed. Bile is a potential source of such biomarkers. Our aim was to apply a proteomic approach to identify a potential biomarker in bile that differentiates between malignant and benign disease, and to assess its diagnostic accuracy. Neutrophil gelatinase-associated lipocalin (NGAL) is multi-functional protein, released from activated neutrophils, with roles in inflammation, immune function, and carcinogenesis. It has not previously been described in bile. METHODS: Bile, urine, and serum were collected prospectively from 38 patients undergoing endoscopic retrograde cholangiopancreatography ("discovery" cohort); 22 had benign and 16 had malignant pancreatobiliary disease. Initially, label-free proteomics and immunoblotting were performed in samples from a subset of these patients. Enzyme-linked immunosorbent assay was then performed for NGAL as a potential biomarker on all samples in this cohort. The diagnostic performance of biliary NGAL was then validated in a second, independent group ("validation" cohort) of 21 patients with pancreatobiliary disease (benign n=14, malignant n=7). RESULTS: NGAL levels were significantly raised in bile from the malignant disease group, compared with bile from the benign disease group in the discovery cohort (median 1,556 vs. 480 ng/ml, P=0.007). Biliary NGAL levels had a receiver operating characteristic area under curve of 0.76, sensitivity 94%, specificity 55%, positive predictive value 60%, and negative predictive value 92% for distinguishing malignant from benign causes. Biliary NGAL was independent of serum biochemistry and carbohydrate antigen 19-9 (CA 19-9) in differentiating between underlying benign and malignant disease. No significant differences in serum and urine NGAL levels were found between benign and malignant disease. Combining biliary NGAL and serum CA 19-9 improved diagnostic accuracy for malignancy (sensitivity 85%, specificity 82%, positive predictive value 79%, and negative predictive value 87%). The diagnostic accuracy of biliary NGAL was confirmed in the second independent validation cohort. CONCLUSIONS: NGAL in bile is a novel potential biomarker to help distinguish benign from malignant biliary obstruction.

A comparison of tumour M2-PK with carcinoembryonic antigen and CA19-9 in patients undergoing liver resection for colorectal metastases.

BACKGROUND: The currently available tumour markers used in the management of patients with colorectal metastases are of limited value. Tumour M2-pyruvate kinase (TuM2-PK), a tumour-associated isoenzyme of pyruvate kinase, is elevated in patients with gastrointestinal cancer. This study has measured TuM2-PK levels in patients before and after resection of colorectal liver metastases (CLM). MATERIALS AND METHODS: Fifty patients with CLM and no local residual disease had TuM2-PK levels measured before liver resection. In 20 patients, TuM2-PK levels were repeated at 2 weeks, 5 weeks and 5 months after resection. Plasma levels were analysed by enzyme-linked immunosorbent assay (ScheBo, Giessen, Germany). Carcinoembryonic antigen (CEA) and CA19-9 levels were measured at the same time periods by electrochemiluminescence immunoassay. CEA, CA19-9 and TuM2-PK levels were compared with the tumour number, volume, differentiation and stage. Cut-off values used for TuM2-PK, CEA and CA19-9 were 15 IU/ml, 10 ng/ml and 39 IU/ml, respectively. RESULTS: TuM2-PK was elevated in 68%, CEA in 62% and CA19-9 in 40% of patients with CLM. TuM2-PK+CEA was elevated in 88% and TuM2-PK+CA19-9 in 78% of patients. A significant correlation was observed between tumour volume and CEA (r=0.34, P<0.05) and CA19-9 (r=0.49, P<0.005). TuM2-PK levels did not show a significant correlation with tumour differentiation, volume or the number of metastases. At 2 weeks after liver resection, CEA and CA19-9 levels had decreased to normal value in 73 and 67% of patients, respectively, but TuM2-PK remained elevated in all patients. At 5 weeks, TuM2-PK, CEA and CA19-9 levels decreased to normal in 64, 93 and 70% of patients, respectively, and at 5 months levels were normal in 58, 92 and 67%. CONCLUSION: Plasma TuM2-PK is commonly elevated in patients with CLM. Levels do not correlate with tumour volume, number or differentiation. Levels remain elevated after liver resection, the cause of which requires further investigation.