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

Recent Advancement in Diagnosis of Biliary Tract Cancer through Pathological and Molecular Classifications

Biliary tract cancers (BTCs), including intrahepatic, perihilar, and distal cholangiocarcinomas, as well as gallbladder cancer, are a diverse group of cancers that exhibit unique molecular characteristics in each of their anatomic and pathological subtypes. The pathological classification of BTCs compromises distinct growth patterns, including mass forming, periductal infiltrating, and intraductal growing types, which can be identified through gross examination. The small-duct and large-duct types of intrahepatic cholangiocarcinoma have been recently introduced into the WHO classification. The presentation of typical clinical symptoms, as well as the extensive utilization of radiological, endoscopic, and molecular diagnostic methods, is thoroughly detailed in the description. To overcome the limitations of traditional tissue acquisition methods, new diagnostic modalities are being explored. The treatment landscape is also rapidly evolving owing to the emergence of distinct subgroups with unique molecular alterations and corresponding targeted therapies. Furthermore, we emphasize the crucial aspects of diagnosing BTC in practical clinical settings.

Bile liquid biopsy in biliary tract cancer

Biliary tract cancers are heterogeneous in etiology, morphology and molecular characteristics thus impacting disease management. Diagnosis is complex and prognosis poor. The advent of liquid biopsy has provided a unique approach to more thoroughly understand tumor biology in general and biliary tract cancers specifically. Due to their minimally invasive nature, liquid biopsy can be used to serially monitor disease progression and allow real-time monitoring of tumor genetic profiles as well as therapeutic response. Due to the unique anatomic location of biliary tract cancer, bile provides a promising biologic fluid for this purpose. This review focuses on the composition of bile and the use of these various components, ie, cells, extracellular vesicles, nucleic acids, proteins and metabolites as potential biomarkers. Based on the disease characteristics and research status of biliary tract cancer, considerable effort should be made to increase understanding of this disease, promote research and development into early diagnosis, develop efficient diagnostic, therapeutic and prognostic markers.

Pathological and molecular diagnoses of early cancer with bile and pancreatic juice

The dismal prognosis of pancreaticobiliary malignancies is mainly attributed to the extremely difficult detection of early-stage lesions, including intraepithelial neoplasia. To improve prognosis, several studies on the early detection of cancer have been conducted using bile and pancreatic juices for pathological or molecular analyses. One approach is liquid biopsy that includes information about the tumor, such as circulating tumor cells, circulating tumor DNA, microRNAs, and exosomes released by the tumor. Another approach is proteomics/metabolomics that reflects specific conditions in the tumor. These two approaches lead to artificial intelligence-based multiomics analyses that comprises genomics, proteomics/metabolomics, and transcriptomics. Based on the findings of molecular analysis, pathological analysis using immunohistochemical staining/fluorescence in situ hybridization has also been developed. Moreover, there have been reports of new methods/ingenuities for obtaining appropriate samples for the diagnosis of early-stage cancer. Here we review the knowledge on cutting-edge pathological and molecular analyses of bile and pancreatic juices, introduce some ingenuities in sampling and sample processing to promote effective clinical practice, and provide a basis for future studies.

Research progress of bile biomarkers and their immunoregulatory role in biliary tract cancers

Biliary tract cancers (BTCs), including cholangiocarcinoma and gallbladder carcinoma, originate from the biliary epithelium and have a poor prognosis. Surgery is the only choice for cure in the early stage of disease. However, most patients are diagnosed in the advanced stage and lose the chance for surgery. Early diagnosis could significantly improve the prognosis of patients. Bile has complex components and is in direct contact with biliary tract tumors. Bile components are closely related to the occurrence and development of biliary tract tumors and may be applied as biomarkers for BTCs. Meanwhile, arising evidence has confirmed the immunoregulatory role of bile components. In this review, we aim to summarize and discuss the relationship between bile components and biliary tract cancers and their ability as biomarkers for BTCs, highlighting the role of bile components in regulating immune response, and their promising application prospects.

Diagnosis Biomarkers of Cholangiocarcinoma in Human Bile: An Evidence-Based Study

Simple Summary

A liquid biopsy has the characteristics of low trauma and easy acquisition in the diagnosis of cholangiocarcinoma. Many researchers try to find diagnostic or prognostic biomarkers of CCA through blood, urine, bile and other body fluids. Due to the close proximity of bile to the lesion and the stable nature, bile gradually comes into people’s view. The evaluation of human bile diagnostic biomarkers is not only to the benefit of screening more suitable clinical markers but also of exploring the pathological changes of the disease.

Abstract

Cholangiocarcinoma (CCA) is a multifactorial malignant tumor of the biliary tract, and the incidence of CCA is increasing in recent years. At present, the diagnosis of CCA mainly depends on imaging and invasive examination, with limited specificity and sensitivity and late detection. The early diagnosis of CCA always faces the dilemma of lacking specific diagnostic biomarkers. Non-invasive methods to assess the degree of CAA have been developed throughout the last decades. Among the many specimens looking for CCA biomarkers, bile has gotten a lot of attention lately. This paper mainly summarizes the recent developments in the current research on the diagnostic biomarkers for CCA in human bile at the levels of the gene, protein, metabolite, extracellular vesicles and volatile organic compounds.

Antibody array-based proteomic screening of novel biomarkers in malignant biliary stricture

BACKGROUND

Distinguishing between benign and malignant bile duct strictures has long been a diagnostic challenge in clinical practice.

OBJECTIVE

This study aimed to discover novel biomarkers in bile to improve the diagnostic accuracy of malignant biliary strictures.

METHODS

Bile samples were collected from 6 patients with malignant or benign biliary stricture, respectively. Protein profiles of the bile were analyzed with a semi-quantitative human antibody array of 440 proteins. Then the differential expressed proteins were screened by Venn diagram analysis. Following this, the accuracy of these potential biomarkers for discriminating between malignant and non-malignant biliary strictures was validated in a larger (n= 40) group of patients using lasso analysis.

RESULTS

Twenty proteins were found differentially expressed in malignant versus benign biliary strictures, 6 of which were identified by Venn diagram analysis to be up-regulated regardless of the location of biliary strictures. Among the 6 biomarkers, bile lipocalin-2, P-cadherin, and adipsin showed better diagnostic utility than that of bile CA19-9. Lasso analysis identified that lipocalin-2, P-cadherin and CA19-9 as a group of makers best distinguished malignant from benign strictures.

CONCLUSIONS

Lipocalin-2 and P-cadherin measurements in bile could be clinically useful for the detection of malignant biliary strictures.

Liquid Biopsy from Bile-Circulating Tumor DNA in Patients with Biliary Tract Cancer

Simple Summary

Utilization of cell free DNA for diagnosing and monitoring patients with biliary tract cancers is emerging and promising. The strength of the present study is in its description of a novel approach using bile rather than blood or tissue samples, which is particularly relevant in biliary tract cancers. This paper largely serves as a proof of concept that ctDNA from bile is potentially feasible.

Abstract

Although liquid biopsy of blood is useful for cancer diagnosis and prediction of prognosis, diagnostic and prognostic value of ctDNA in bile fluid for BTCs are not clear yet. To determine whether liquid biopsy for circulating tumor DNA (ctDNA) can replace tissue biopsy when assessing somatic mutations in biliary tract cancers (BTCs). Bile samples were obtained from 42 patients with BTC. Matched formalin-fixed paraffin-embedded (FFPE) samples were obtained from 20 of these patients and matched plasma samples from 16 of them. Droplet digital PCR (ddPCR) was used for detection KRAS somatic mutation. KRAS mutations were identified in the bile ctDNA of 20 of 42 (48%) patients. Patients with mutant KRAS showed significantly worse survival than those with wild-type KRAS (2-year survival rates: 0% vs. 55.5%, respectively; p = 0.018). There was 80.0% mutational concordance between the paired bile ctDNA and FFPE samples, and 42.9% between the plasma and FFPE samples. On transcriptomic sequencing of one set of paired bile and FFPE samples, expression level of KRAS-associated signaling oncogenes in the bile and tissue samples showed a strong positive correlation (r = 0.991, p < 0.001). Liquid biopsy of bile reliably detect mutational variants within the bile ctDNA of BTC patients. These results suggest that bile is an effective biopsy fluid for ctDNA analysis.

Biomarkers in the diagnosis of pancreatic cancer: Are we closer to finding the golden ticket?

Pancreatic cancer (PC) is a leading cause of cancer related mortality on a global scale. The disease itself is associated with a dismal prognosis, partly due to its silent nature resulting in patients presenting with advanced disease at the time of diagnosis. To combat this, there has been an explosion in the last decade of potential candidate biomarkers in the research setting in the hope that a diagnostic biomarker may provide a glimmer of hope in what is otherwise quite a substantial clinical dilemma. Currently, serum carbohydrate antigen 19-9 is utilized in the diagnostic work-up of patients diagnosed with PC however this biomarker lacks the sensitivity and specificity associated with a gold-standard marker. In the search for a biomarker that is both sensitive and specific for the diagnosis of PC, there has been a paradigm shift towards a focus on liquid biopsy and the use of diagnostic panels which has subsequently proved to have efficacy in the diagnosis of PC. Currently, promising developments in the field of early detection on PC using diagnostic biomarkers include the detection of microRNA (miRNA) in serum and circulating tumour cells. Both these modalities, although in their infancy and yet to be widely accepted into routine clinical practice, possess merit in the early detection of PC. We reviewed over 300 biomarkers with the aim to provide an in-depth summary of the current state-of-play regarding diagnostic biomarkers in PC (serum, urinary, salivary, faecal, pancreatic juice and biliary fluid).

Role of neutrophil gelatinase-associated lipocalin in renal cell carcinoma

Human neutrophil gelatinase-associated lipocalin (NGAL) is a glycoprotein present in a wide variety of tissues and cell types. It exists as a monomer of 25 kDa, a homodimer of 45 kDa or a heterodimer of 135 kDa (disulfide bound to latent matrix metalloproteinase-9). NGAL is considered the biochemical gold standard for the early diagnosis of acute kidney injury and has attracted much attention as a diagnostic biomarker. NGAL has controversial (i.e. both beneficial and detrimental) effects on cellular processes associated with tumor development, such as cell proliferation, survival, migration, invasion and drug resistance. Therefore, the present review aimed at clarifying the role of NGAL in renal cell carcinoma (RCC). Relevant studies of NGAL and RCC were searched in PubMed and relevant information about the structure, expression, function and mechanism of NGAL in RCC were summarized. Finally, the following conclusions could be drawn from the literature: i) NGAL can be detected in cancer tissues, serum and urine of patients with RCC; ii) NGAL is not a suitable diagnostic marker for early screening of RCC; iii) NGAL expression may be used to predict the prognosis of patients with RCC; and iv) Further research on NGAL may be helpful to decrease sunitinib resistance and find new treatment strategies for RCC.

Pilot Multi-Omic Analysis of Human Bile from Benign and Malignant Biliary Strictures: A Machine-Learning Approach

Cholangiocarcinoma (CCA) and pancreatic adenocarcinoma (PDAC) may lead to the development of extrahepatic obstructive cholestasis. However, biliary stenoses can also be caused by benign conditions, and the identification of their etiology still remains a clinical challenge. We performed metabolomic and proteomic analyses of bile from patients with benign (n = 36) and malignant conditions, CCA (n = 36) or PDAC (n = 57), undergoing endoscopic retrograde cholangiopancreatography with the aim of characterizing bile composition in biliopancreatic disease and identifying biomarkers for the differential diagnosis of biliary strictures. Comprehensive analyses of lipids, bile acids and small molecules were carried out using mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (¹H-NMR) in all patients. MS analysis of bile proteome was performed in five patients per group. We implemented artificial intelligence tools for the selection of biomarkers and algorithms with predictive capacity. Our machine-learning pipeline included the generation of synthetic data with properties of real data, the selection of potential biomarkers (metabolites or proteins) and their analysis with neural networks (NN). Selected biomarkers were then validated with real data. We identified panels of lipids (n = 10) and proteins (n = 5) that when analyzed with NN algorithms discriminated between patients with and without cancer with an unprecedented accuracy.

Usefulness of bile as a biomarker via ferroptosis and cysteine prenylation in cholangiocarcinoma; role of diagnosis and differentiation from benign biliary disease

BACKGROUND

Cholangiocarcinoma (CCA) is a malignant cancer of the biliary tract with a poor prognosis. Herein, we investigated possible mechanism of extrahepatic CCA (eCCA) by dysregulated iron metabolism and post-translational modifications (PTMs). Further, we evaluated potential biomarkers in the bile fluid for diagnosis of eCCA and differentiation between eCCA and benign biliary disease.

METHODS

From August 2018 to April 2019, we obtained bile fluids from 46 patients; 28 patients with eCCA (eCCA group) and 18 patients with common bile duct stone (Control group) via percutaneous transhepatic biliary drainage. We examined the levels of reduced glutathione (GSH), peroxide, ferrous iron [Fe⁺²], glutathione peroxidase (GP_X) and farnesyl transferase/geranylgeranyl transferase type-1 subunit alpha (FNTA) concentration in bile fluids to clarify the mechanism of ferroptosis and prenylation.

RESULTS

The remarkable difference of PTMs was that FNTA which means prenylated cysteine as regulator was significantly decreased in eCCA than that of control. In addition, level of GSH, peroxide, GP_X and ferrous iron [Fe⁺²] were significantly depleted in eCCA than control. These results demonstrate that PTM, dysregulated iron metabolism and GP_X-regulated ferroptosis with GSH depletion through cysteine modification in bile are possible mechanisms of eCCA. Liquid Chromatography (LC)-Mass Spectrometry (MS) analysis, several oncogenic pathways including MYC target, apoptosis, fatty acid metabolism, P53 and mTORC1 were enriched in eCCA.

CONCLUSIONS

In conclusion, redox-dependent modification of cysteine and ferroptosis in bile fluids are possible mechanisms of eCCA. Several protein and oncogenic pathways related to PTM which are seen in eCCA tissues were also enriched in bile fluids. It suggests that bile fluid represents the oncogenic characteristics of eCCA tissues. Therefore, bile fluids have a role of a biomarker for diagnosis in eCCA, especially, differentiation of eCCA from benign biliary stricture.

Lipocalin-2 expression and function in pancreatic diseases

Lipocalin-2 (LCN2) is a secreted molecule, expressed in various cell types, that is involved in the progression of numerous diseases and disorders. The biological functions and expression levels of LCN2 in diseases including pancreatic cancer, pancreatitis (acute and chronic), and diabetes mellitus, suggest the potential role of LCN2 as a biomarker and/or therapeutic target. However, findings on the role of LCN2 in pancreatic diseases have been contradictory. In pancreatic cancer and pancreatitis, LCN2 has been identified as a potential biomarker; increased expression levels in various biological specimens correlate with the presence of the disease and may be able to differentiate cancer and chronic pancreatitis from healthy subjects. LCN2 is also known to be an adipokine; it is upregulated in obesity and is a common co-factor in the development of pancreatic diseases. Emerging research suggests LCN2 is elevated in type 2 diabetes mellitus, but the exact role of LCN2 in this disease is not clear. In this review, we summarize research on LCN2 as it relates to pancreatic diseases, highlighting the discrepancies in the literature. By explaining and clarifying the role of LCN2 in these disorders, we aim to promote research in developing novel diagnostic and treatment strategies to reduce the burden of pancreatic diseases.

Does Whole-Blood Neutrophil Gelatinase-Associated Lipocalin Stratify Acute Kidney Injury in Critically Ill Patients?

Purpose

To analyse the capacity of whole-blood NGAL (wbNGAL) to stratify AKI in critically ill patients with and without sepsis.

Methods

Whole-blood NGAL was measured with a point-of-care device at admission and 48 hours later in patients admitted to a general ICU. Patients were classified by the AKIN and KDIGO classifications at admission and 24 and 48 hours. We performed an ROC curve analysis. wbNGAL values at admission were compared in patients with sepsis and septic shock.

Results

The study included 100 consecutively admitted patients (40 female) with mean age 59.1 ± 17.8 years. Thirty-three patients presented AKI at admission, and 10 more developed it in the next 48 h. Eighteen patients had AKI stage 3, 14 of them at admission. Nine patients required renal replacement therapy. According to KDIGO at admission, wbNGAL values were 78 μg/L (60-187) in stage 0 (n = 67), 263 μg/L (89-314) in stage 1 (n = 8), 484 μg/L (333-708) in stage 2 (n = 11), and 623 μg/L (231-911) in stage 3 (n = 14), p = 0.0001 for trend. Ten patients did not complete 48 hours of study: 6 of 10 were discharged (initial wbNGAL 130 μg/L (60-514)) and 4 died (773 μg/L (311-1010)). The AUROC curve of wbNGAL to predict AKI was 0.838 (95% confidence interval 0.76-0.92, p = 0.0001), with optimal cut-off value of 178 μg/L (sensitivity 76.7%, specificity 78.9%, p < 0.0001). At admission, twenty-nine patients had sepsis, of whom 20 were in septic shock. wbNGAL concentrations were 81 μg/L (60-187) in patients without sepsis, 481 (247-687) in those with sepsis, and 623.5 μg/L (361-798) in the subgroup of septic shock (p < 0.0001).

Conclusions

Whole-blood NGAL concentration at ICU admission was a good stratifier of AKI in critically ill patients. However, wbNGAL concentrations were higher in septic patients irrespective of AKI occurrence.

Diagnosis of cholangiocarcinoma in primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic inflammatory disease of the hepatobiliary system characterized by chronic inflammation, progressive fibrosis, stricture formation and destruction of extrahepatic and intrahepatic bile ducts. Areas covered: The increased incidence of cholangiocarcinoma (CCA) in PSC has been well documented and can be explained by the continuous inflammation in the biliary tree leading to an enhanced dysplasia-carcinoma sequence. Although PSC patients may progress to liver cirrhosis; CCA most commonly occurs between the ages of 30 and 45 years when cirrhosis has not yet developed. Therefore, CCA in patients with PSC occurs earlier than in patients without PSC. Expert commentary: Despite improvement in diagnostic methods and devices, the dilemma of diagnosing CCA in patients with PSC has not been solved yet and needs further investigation.

Cystic fluid neutrophil gelatinase-associated lipocalin (NGAL) concentration in differential diagnosis of pancreatic cystic lesions: a new factor enters the scene?

Introduction

Neutrophil gelatinase-associated lipocalin – 25 kDa peptide – is at present one of the most fascinating and unrecognised proteins implicated in the process of tumour development. Precise assessment of pancreatic cystic lesions is crucial for selecting available treatment options, such as conservative therapy or surgical resection.

Aim

To determine the utility of NGAL concentration in cyst fluid obtained by endoscopic ultrasound (EUS) with EUS-guided fine-needle aspiration (EUS-FNA) to distinguish neoplastic pancreatic cysts from pseudocysts.

Material and methods

Twenty-two patients underwent EUS and FNA of a pancreatic cystic lesion; 9 of these patients underwent surgical resection, providing a histologic diagnosis of the cystic lesion. Furthermore, the final diagnosis was based on cyst fluid cytology, cyst fluid tumour markers (CEA, CA 72-4, CA 19-9), and medical history. Patients were divided in two groups: cystic neoplasms and inflammatory cysts (pseudocysts).

Results

The final diagnosis was pseudocyst in 7 patients, serous cystadenoma in 4, mucinous cystadenoma in 3, intraductal papillary mucinous neoplasms in 6 patients, and cystic form of pancreatic adenocarcinoma in 2. Cyst fluid analysis of these patients showed that median cyst fluid NGAL for the cystic neoplasm group (211 ng/ml; n = 15) was significantly lower (p = 0.02) than the inflammatory cystic group (4689 ng/ml; n = 7). Correlation analysis showed that only fluid CA 72-4 was positively related to NGAL (r = 0.8, p < 0.01).

Conclusions

In this single-centre study, pancreatic cyst fluid NGAL concentration appeared to be useful in distinguishing neoplastic pancreatic cysts from pseudocysts. Larger studies are recommended to evaluate this role further.

A comparative proteomic analysis of bile for biomarkers of cholangiocarcinoma

Cholangiocarcinoma is a primary malignant tumor of the bile duct epithelium. Cholangiocarcinoma is usually detected at an advanced stage when successful treatment is no longer possible. As the tumor originates from the bile duct epithelium, bile is an ideal source of tumor biomarkers for cholangiocarcinoma. In this study, we used a quantitative proteomics approach to identify potential tumor-associated proteins in the bile fluid of six cholangiocarcinoma patients. Three different gross-appearance tumor types were used in the analysis: mass-forming type ( n = 2), periductal infiltrating type ( n = 2), and intraductal growth type ( n = 2). Two bile samples from non-cancerous patients were used as controls. Isobaric labeling, coupled with Tandem mass spectrometry, was used to quantify protein levels in the bile of cholangiocarcinoma and control patients. In all, 63 proteins were significantly increased in cholangiocarcinoma bile compared to normal bile. Alpha-1-antitrypsin was one of the overexpressed proteins that increased in cholangiocarcinoma bile samples. Immunohistochemical analysis revealed that alpha-1-antitrypsin was detected in 177 (50%) of 354 cholangiocarcinoma tissues from our Tissue Bank. Immunoblotting of 54 cholangiocarcinoma bile samples showed that alpha-1-antitrypsin was positive in 38 (70%) samples. Fecal enzyme-linked immunosorbent assay showed that alpha-1-antitrypsin level was able to distinguish cholangiocarcinoma patients from normal individuals. In conclusion, alpha-1-antitrypsin is a potential marker for early diagnosis of cholangiocarcinoma.

Can NGAL be employed as prognostic and diagnostic biomarker in human cancers? A systematic review of current evidence

BACKGROUND

Some studies have reported differentially altered neutrophil gelatinase-associated lipocalin (NGAL) levels in several malignancies. We evaluated NGAL measured in plasma or urine as both prognostic and diagnostic marker for different types of human tumors.

METHODS

We performed systematic electronic searches in Medline, Embase and CRDTAS. Studies were included if they evaluated NGAL as a prognostic or diagnostic marker for human cancers. The selection of the studies, screening of the full texts and data extraction were conducted independently by 2 authors. We used the random-effects model for the meta-analyses. A methodological assessment was completed.

RESULTS

We included 35 studies dedicated to colorectal, pancreas, breast, thyroid, gastric, kidney, endometrial, brain, liver, lung, esophageal, oral and ovarian cancers. Our meta-analyses showed that, in patients with colorectal and breast cancer, positive NGAL expression was associated with a decrease of disease-free survival (hazard ratio [HR] = 2.27, 95% confidence interval [95% CI], 1.54-3.36; HR = 1.78, 95% CI, 1.33-2.38, respectively). NGAL was a negative prognostic marker of overall survival in colorectal (HR = 2.37, 95% CI, 1.68-3.34) and endometrial (HR = 4.38, 95% CI, 1.9-10.12) cancers. Discriminative power of NGAL between cancer patients and control was moderate in colorectal cancer (area under the curve [AUC] = 0.6; pooled sensitivity 0.56; pooled specificity 0.72), acceptable in pancreatic cancer (AUC = 0.8; pooled sensitivity 0.6; pooled specificity 0.8) and good in thyroid cancer (AUC = 0.9; pooled sensitivity 0.85; pooled specificity 0.96).

CONCLUSIONS

NGAL determination in plasma and urine could be useful in the prognosis of colorectal and breast cancer, but its prognostic accuracy remains uncertain for other human tumors.

Neutrophil Gelatinase-Associated Lipocalin (NGAL) concentration in urine is superior to CA19-9 and Ca 125 in differentiation of pancreatic mass: Preliminary report

BACKGROUND

Currently pancreatic cancer is the fourth leading cause of cancer-related death worldwide. Because of its late manifestation and consequent dismal prognosis, there is an urgent need to develop highly sensitive and specific marker. Neutrophil Gelatinase-Associated Lipocalin (NGAL) recently emerged as a protein playing an important role in carcinogenesis of various neoplasms.

OBJECTIVE

Our aim was to assess the potential of urine and bile concentration of NGAL in differentiating pancreatic adenocarcinoma from chronic pancreatitis.

METHODS

Forty-two patients operated on due to pancreatobiliary lesions were enrolled in this study. All enrolled patients had eGFR within reference range. Levels of CEA, CA 125 and Ca19-9 were assessed using standard laboratory protocols. A sample of urine was collected prior to the surgery. Intraoperatively a 5 ml sample of bile was collected directly from the common bile duct. Bile and urine levels of NGAL were measured using a ELISA kit. After standard pathological examination of specimens obtained during surgery, patients were divided into 2 groups: 21 patients with pancreatic adenocarcinoma and 15 patients with focal chronic pancreatitis.

RESULTS

NGAL concentration in bile in patients with PDAC vs CP was 75.72 ± 16.05 ng/mL vs 62.62 ± 18.6 ng/mL respectively (p= 0,011). NGAL concentration in urine was 43.26 ± 21.21 ng/mL vs 17.96 ± 14.58 ng/mL (p= 0.002) respectively. In order to compare these markers with routinely used ones, ROC curve was built for Ca125 to establish cutoff point and in case of CA19-9 clinically used cutoff (≥ 37U/mL) was applied. Sensitivity and specificity for NGALurine with cutoff value of 27 ng/mL was 80.95% and 80% respectively, while these values for NGALbile were 71.43% and 80% respectively. Ca19-9 measured in plasma with clinically used cutoff value had sensitivity of 71.43% and specificity of 73.33%. Sensitivity and specificity for Ca 125 measured in plasma with cutoff value of 13 U/mL were 85.71% and 66.67% respectively.

CONCLUSIONS

In conclusion, NGAL in urine and bile are remarkably accurate in differentiating pancreatic mass due to chronic pancreatitis from pancreatic adenocarcinoma. Therefore, NGAL concentrations in bile and urine should be further investigated in order to assess their usefulness in early pancreatic adenocarcinoma diagnosis.

Lipocalin 2 (LCN2) is a promising target for cholangiocarcinoma treatment and bile LCN2 level is a potential cholangiocarcinoma diagnostic marker

Cholangiocarcinoma (CCA) is a devastating disease due to resistance to traditional chemotherapies and radiotherapies. New therapeutic strategies against CCA are urgently needed. This study investigated the role of lipocalin-2 (LCN2) in human cholangiocarcinoma as a potential therapeutic target and diagnostic marker. So far, the role of LCN2 in cancer is still controversial and studies regarding the role of LCN2 in CCA are limited. LCN2 knockdown inhibited CCA cell growth in vitro and in vivo through induction of cell cycle arrest at G0/G1 phases and decreased metastatic potential due to repression of epithelial-mesenchymal transition (EMT). Overexpression of LCN2 in CCA cells increased cell metastatic potential. We showed for the first time that the N-myc downstream regulated gene 1 (NDRG1) and NDRG2, known as tumor suppressor genes, are negatively regulated by LCN2 in CCA cells. LCN2 concentration in bile was higher in patients with CCA than that in patients with gallstones, with a cutoff value of 20.08 ng/ml making this a potential diagnostic marker. Higher LCN2 expression was associated with worse survival in patients with CCA. LCN2 is a promising target for CCA treatment and bile LCN2 level is a potential diagnostic marker for CCA.

Performance of bile aspiration plus brushing to diagnose malignant biliary strictures during endoscopic retrograde cholangiopancreatography

BACKGROUND AND STUDY AIMS

Endobiliary brushing during endoscopic retrograde cholangiopancreatography (ERCP) is the main technique used to diagnose a malignant stricture, but has a poor sensitivity. This study evaluated the diagnostic performance of bile aspiration associated with biliary brushing during ERCP to diagnose a malignant stricture, compared to brushing alone.

PATIENTS AND METHODS

Between January 2007 and December 2012, all consecutive patients undergoing ERCP to treat a biliary stricture were included. After a biliary sphincterotomy, 3 mL to 10 mL of bile was aspirated into the brush catheter and collected in a dry sterile tube before and after brushing (to yield three samples). Brushing was performed as commonly recommended.

RESULTS

One hundred eleven patients (68 males, 43 females) were included; mean age 67 ± 15.4 years. A final diagnosis of malignant stricture was established in 51 patients, including 43 cholangiocarcinomas; 60 patients had benign strictures. Specificity (Sp) and positive predictive values were 100% for all samples. The diagnostic performance of the three-sample combination of bile aspiration + brushing + bile aspiration was significantly greater than brushing alone (P = 0.004): sensitivity (Se) = 84.3 % vs. Se = 66.7 %. The three-sample combination gave a negative predictive value of 88.2 %, and a diagnostic accuracy of 92.8 %. When suspicious results were added to malignant results as positive results, the three-sample combination gave Sp = 91.7 % and Se = 94.1 %.

CONCLUSIONS

In cases of biliary stricture, conducting bile aspiration before and after brushing significantly increased the ability to diagnose a malignant stricture with a sensitivity of 84.3 % (P = 0.004).

Clinical proteomics-driven precision medicine for targeted cancer therapy: current overview and future perspectives

Cancer is a common disease that is a leading cause of death worldwide. Currently, early detection and novel therapeutic strategies are urgently needed for more effective management of cancer. Importantly, protein profiling using clinical proteomic strategies, with spectacular sensitivity and precision, offer excellent promise for the identification of potential biomarkers that would direct the development of targeted therapeutic anticancer drugs for precision medicine. In particular, clinical sample sources, including tumor tissues and body fluids (blood, feces, urine and saliva), have been widely investigated using modern high-throughput mass spectrometry-based proteomic approaches combined with bioinformatic analysis, to pursue the possibilities of precision medicine for targeted cancer therapy. Discussed in this review are the current advantages and limitations of clinical proteomics, the available strategies of clinical proteomics for the management of precision medicine, as well as the challenges and future perspectives of clinical proteomics-driven precision medicine for targeted cancer therapy.

Cholangiocarcinoma: Current opinion on clinical practice diagnostic and therapeutic algorithms: A review of the literature and a long-standing experience of a referral center

In the oncology landscape, cholangiocarcinoma is a challenging disease in terms of both diagnosis and treatment. Besides anamnesis and clinical examination, a definitive diagnosis of cholangiocarcinoma should be supported by imaging techniques (US, CT, MRI) and invasive investigations (ERC or EUS with brushing and FNA or US or CT-guided biopsy) followed by pathological confirmation. Surgery is the main curative option, so resectability of the tumour should be promptly assessed. Moreover, jaundice must be evaluated at the outset because biliary tract decompression with drainage and stent placement may be required. If the patient is resectable, pre-operative assessment of postoperative liver function is mandatory. After a curative resection, an adjuvant therapy may be administered. Otherwise, in cases with macroscopic residual disease after surgery or locally recurrent or unresectable cholangiocarcinoma at the diagnosis, first-line chemotherapy is the preferred strategy, possibly associated with radiotherapy and/or locoregional treatments. As the diagnostic and therapeutic pathway for cholangiocarcinoma can be declined in different modalities, patients should be promptly referred to a multidisciplinary team in a tertiary centre, familiar with this rare but lethal disease. Hence, the aim of the present paper is to focus on diagnostic and therapeutic algorithms based on the common guidelines and also on the clinical practice of multispecialist expert groups.

Bile proteomics for differentiation of malignant from benign biliary strictures: a pilot study

BACKGROUND

Determining the etiology of biliary strictures is challenging, and the sensitivities of the current tests to diagnose them are low. Protein biomarkers in bile, in combination with other tests, may improve sensitivity in diagnosing biliary strictures.

OBJECTIVE

To analyse the differential abundance of proteins in benign and malignant biliary strictures through proteomic analysis of bile.

METHODS

In this prospective, cross-sectional study, bile was aspirated in 24 patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) including six patients with primary sclerosing cholangitis (PSC), three with cholangiocarcinoma (CCA), ten with pancreatic cancer, and five with benign biliary conditions. Liquid chromatography/mass spectrometry was used to examine the bile for differential abundance of protein biomarkers. The relative abundance of various proteins was compared in the malignant vs. benign groups and in CCA vs. PSC.

RESULTS

The majority of the proteins identified in bile were similar to those of the plasma (plasma proteins) and certain proteins were differentially expressed among the different groups (CCA, pancreatic cancer, PSC or benign). A total of 18 proteins were identified as being more abundant in the malignant group (CCA and pancreatic cancer) than in the benign strictures group, including myeloperoxidase, complement C3, inter-alpha-trypsin inhibitor heavy chain H4, apolipoprotein B-100, and kininogen-1 isoform 2. A total of 30 proteins were identified to be less abundant in the malignant group than in the benign group, including trefoil factor 2, superoxide dismutase [Cu-Zn], kallikrein-1, carboxypeptidase B and trefoil factor 1.

CONCLUSIONS

Protein biomarkers in bile may differentiate malignant from benign biliary strictures. Larger studies are warranted to validate these observations.

Biomarkers in bile-complementing advanced endoscopic imaging in the diagnosis of indeterminate biliary strictures

Biliary strictures present a diagnostic challenge and a conundrum, particularly when an initial work up including abdominal imaging and endoscopic retrograde cholangiopancreatography based sampling are non-diagnostic. Advances in endoscopic imaging have helped us diagnose these strictures better. However, even with modern technology, some strictures remain a diagnostic challenge. The proximity of bile fluid to the bile duct epithelia makes it an attractive option to investigate for bio-markers, which might be representative of the functions/abnormal changes taking place in the biliary system. A number of biomarkers in bile have been discovered recently in approaching biliary strictures with their potential future diagnostic utility, further supported by the immunohistochemical analysis of the resected tissue specimens. Novel biliary biomarkers especially carcinoembryonic cell adhesion molecule 6 and neutrophil gelatinase-associated lipocalin seem promising in differentiating malignant from benign biliary strictures. Recent developments in lipidomic profiling of bile are also very promising. Biliary biomarkers appear to complement endoscopic imaging in diagnosing malignant etiologies of biliary stricture. Future studies addressing these biomarkers need to be incorporated to the current endoscopic techniques to determine the best approach in determining the etiology of biliary strictures.

Roles of neutrophil gelatinase-associated lipocalin (NGAL) in human cancer

Cancer remains one of the major cause of death in the Western world. Although, it has been demonstrated that new therapies can improve the outcome of cancer patients, still many patients relapse after treatment. Therefore, there is a need to identify novel factors involved in cancer development and/or progression. Recently, neutrophil gelatinase-associated lipocalin (NGAL) has been suggested as a key player in different cancer types. Its oncogenic effect may be related to the complex NGAL/MMP-9. In the present study, NGAL was analyzed at both transcript and protein levels in different cancer types by analysing 38 public available microarray datasets and the Human Protein Atlas tool.

NGAL transcripts were significantly higher in the majority of solid tumors compared to the relative normal tissues for every dataset analyzed. Furthermore, concordance of NGAL at both mRNA and protein levels was observed for 6 cancer types including bladder, colorectal, liver, lung, ovarian, and pancreatic. All metastatic tumors showed a decrease of NGAL expression when compared to matched primary lesions.

According to these results, NGAL is a candidate marker for tumor growth in a fraction of solid tumors. Further investigations are required to elucidate the function of NGAL in tumor development and metastatic processes.

Bile proteome in health and disease

The study of bile proteins could improve the understanding of physiological processes involved in the regulation of the hepato-biliary system. Researchers have tried for years to investigate the bile proteome but, until recently, only a few tens of proteins were known. The advent of proteomics, availing of large-scale analytical devices paired with potent bioinformatic resources, lately allowed the identification of thousands of proteins in bile. Nevertheless, the knowledge of their role in the hepato-biliary system still represents almost a "blank page in the book of physiology." In this review, we first guide the reader through the historical phases of the analysis of bile protein content, emphasizing the recent progresses achieved through the use of proteomic techniques. Thereafter, we deeply explore the involvement of bile proteins in health and disease, with a particular focus on the discovery of biomarkers for biliary tract malignancies.

Neutrophil gelatinase-associated lipocalin in cancer

Neutrophil gelatinase-associated lipocalin (NGAL), also known as lipocalin-2, is a 178-amino acid protein which exists in three molecular forms, including a 25-kDa monomer, a 45-kDa homodimer, and a 135-kDa heterodimer complexed with matrix metalloproteinase 9 (MMP-9). Polymorphonuclear neutrophils and tubular cells of the kidney are the most representative cellular sources. As such, NGAL is now considered the biochemical gold standard for early diagnosis of acute kidney injury. Recent evidence suggests, however, that ectopic or enhanced expression of NGAL may occur in many other pathologic conditions including cancer. Several epidemiologic studies, as reviewed in this chapter, showed that a variety of malignant tumors consistently overexpressed NGAL with increased concentration in blood, urine, and other biologic fluids. In addition, NGAL was frequently associated with tumor size, stage, and invasiveness. These features thus make it a potential biomarker for malignancy. A number of experimental studies also demonstrated that the ability to bind MMP-9, to scavenge iron into cancer cells along with the effect on subcellular localization of transmembrane proteins such as cadherins and catenins, confers this protein the potential to enhance can cer aggressiveness and makes it an appealing target of future anticancer research.

Identification of potential serum peptide biomarkers of biliary tract cancer using MALDI MS profiling

BACKGROUND

The aim of this discovery study was the identification of peptide serum biomarkers for detecting biliary tract cancer (BTC) using samples from healthy volunteers and benign cases of biliary disease as control groups. This work was based on the hypothesis that cancer-specific exopeptidases exist and that their activities in serum can generate cancer-predictive peptide fragments from circulating proteins during coagulation.

METHODS

This case control study used a semi-automated platform incorporating polypeptide extraction linked to matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) to profile 92 patient serum samples. Predictive models were generated to test a validation serum set from BTC cases and healthy volunteers.

RESULTS

Several peptide peaks were found that could significantly differentiate BTC patients from healthy controls and benign biliary disease. A predictive model resulted in a sensitivity of 100% and a specificity of 93.8% in detecting BTC in the validation set, whilst another model gave a sensitivity of 79.5% and a specificity of 83.9% in discriminating BTC from benign biliary disease samples in the training set. Discriminatory peaks were identified by tandem MS as fragments of abundant clotting proteins.

CONCLUSIONS

Serum MALDI MS peptide signatures can accurately discriminate patients with BTC from healthy volunteers.

Serum and bile NGAL for clinically distinguishing malignant biliary strictures from benign biliary strictures

AIM: To investigate the value of serum and bile neutrophil gelatinase associated lipocalin (NGAL) for distinguishing malignant strictures caused by cholangiocarcinoma (CCA) or pancreatic cancer from benign biliary strictures.

METHODS: The study was performed prospectively on patients admitted for endoscopic retrograde cholangiopancreatography biliary decompression. Forty-four patients with dilated biliary ducts, including 12 cases of CCA, 8 cases of pancreatic cancer, 1 case of carcinoma of the ampulla, and 23 cases of benign biliary strictures, were enrolled. Their sera and bile were collected to measure NGAL. Routine biochemistry including liver function test and routine blood examination was also performed. Enzyme-linked immunosorbent assay was performed to measure the contents of NGAL in serum and bile samples.

RESULTS: Serum NGAL had no significant value for discriminating malignant and benign biliary strictures (mean, 31.10 ng/mL vs 118.35 ng/mL, P = 0.0825). Biliary NGAL levels were significantly raised in the malignant disease group compared with the benign disease group (mean, 199.0 ng/mL vs 466.7 ng/mL, P = 0.0215).

CONCLUSION: Measurement of biliary NGAL, not serum NGAL, may differentiate malignant biliary strictures from benign biliary strictures.

A review of the clinical diagnosis and therapy of cholangiocarcinoma

Cholangiocarcinoma (CCA) is the second most common primary hepatic malignancy worldwide. The incidence of intrahepatic CCA is increasing, whereas that of extrahepatic CCA is decreasing. This review looks at the new advances that have been made in the management of CCA, based on a PubMed and Science Citation Index search of results from randomized controlled trials, reviews, and cohort, prospective and retrospective studies. Aggressive interventional approaches and new histopathological techniques have been developed to make a histological diagnosis in patients with high risk factors or suspected CCA. Resectability of the tumour can now be assessed using multiple radiological imaging studies; the main prognostic factor after surgery is a histologically negative resection margin. Biliary drainage and/or portal vein embolization may be performed before extended radical resection, or liver transplantation may be undertaken in combination with neoadjuvant chemotherapy or chemoradiotherapy. Though many advances have been made in the management of CCA, the standard modality of treatment has not yet been established. This review focuses on the clinical options for different stages of CCA.

An integrated approach for comparative proteomic analysis of human bile reveals overexpressed cancer-associated proteins in malignant biliary stenosis

Proteomics is a key tool in the identification of new bile biomarkers for differentiating malignant and nonmalignant biliary stenoses. Unfortunately, the complexity of bile and the presence of molecules interfering with protein analysis represent an obstacle for quantitative proteomic studies in bile samples. The simultaneous need to introduce purification steps and minimize the use of pre-fractionation methods inevitably leads to protein loss and limited quantifications. This dramatically reduces the chance of identifying new potential biomarkers. In the present study, we included differential centrifugation as a preliminary step in a quantitative proteomic workflow involving iTRAQ labeling, peptide fractionation by OFFGEL electrophoresis and LC-MS/MS, to compare protein expression in bile samples collected from patients with malignant or nonmalignant biliary stenoses. A total of 1267 proteins were identified, including a set of 322 newly described bile proteins, mainly belonging to high-density cellular fractions. The subsequent comparative analysis led to a 5-fold increase in the number of quantified proteins over previously published studies and highlighted 104 proteins overexpressed in malignant samples. Finally, immunoblot verifications performed on a cohort of 8 malignant (pancreatic adenocarcinoma, n=4; cholangiocarcinoma, n=4) and 5 nonmalignant samples (chronic pancreatitis, n=3; biliary stones, n=2) confirmed the results of proteomic analysis for three proteins: olfactomedin-4, syntenin-2 and Ras-related C3 botulinum toxin substrate 1. This article is part of a Special Issue entitled: Biomarkers: A Proteomic Challenge.

Bile carcinoembryonic cell adhesion molecule 6 (CEAM6) as a biomarker of malignant biliary stenoses

Differentiating malignant from nonmalignant biliary stenoses is challenging. This could be facilitated by the measurement of cancer biomarkers in bile. We aimed at (i) identifying new cancer biomarkers by comparative proteomic analysis of bile collected from patients with a malignant or benign biliary stenosis (exploratory phase) and (ii) verifying the accuracy of the newly identified potential biomarkers for discriminating malignant versus nonmalignant biliary stenoses in a larger group of patients (confirmation phase). Overall, 66 proteins were found overexpressed (ratio>1.5) in at least one cancer condition using proteomic analysis and 7 proteins were increased in all malignant/nonmalignant disease comparisons. Preliminary screening by immunoblot highlighted carcinoembryonic cell adhesion molecule 6 (CEAM6), a cell surface protein overexpressed in many human cancers, as an interesting candidate biomarker. ELISA subsequently confirmed CEAM6 as a potential bile biomarker for distinguishing malignant from benign biliary stenoses with a receiver operating characteristic (ROC) area under the curve (AUC) of 0.92 (specificity 83%, sensitivity 93%, positive predictive value 93%, and negative predictive value 83%). No significant difference in serum CEAM6 level was found between malignant and nonmalignant samples. Combining bile CEAM6 and serum CA19-9 in a panel further improved diagnostic accuracy for malignant stenoses (AUC 0.96, specificity 83%, sensitivity 97%, positive predictive value 93%, and negative predictive value 91%). CEAM6 measurement in bile could be clinically useful to discriminate between malignant and nonmalignant causes of biliary stenosis. This article is part of a Special Issue entitled: Biomarkers: A Proteomic Challenge.

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.

Advances in proteomics of digestive juices for the diagnosis of digestive system malignancies

Body fluid proteomic analysis is a new technology and strategy for disease diagnosis and treatment. Blood is the most commonly used specimen in body fluid proteomics, but as a systemic fluid, it has limitations because of complex composition and low abundance of disease-related proteins. In contrast, local body fluids are closest to the lesions, contain more pathological information, and therefore are more valuable in clinical proteomics. In the digestive system, there are a variety of body fluids which are considered potential reservoirs of biomarkers for their quality and quantity of proteins will alter during lesions occurring in corresponding organs. In recent years, more and more clinical proteomic analyses of saliva, gastric juice, bile and pancreatic juice has been reported and the proteins related to digestive cancers have been found, and some proteins show application potentials in cancer diagnosis. However, the proteomic analyses of digestive juices are facing technical challenges in terms of the reproducibility of results and standardization of specimen handling.

The multifaceted roles of neutrophil gelatinase associated lipocalin (NGAL) in inflammation and cancer

Neutrophil gelatinase associated lipocalin (NGAL), also known as oncogene 24p3, uterocalin, siderocalin or lipocalin 2, is a 24kDa secreted glycoprotein originally purified from a culture of mouse kidney cells infected with simian virus 40 (SV-40). Subsequent investigations have revealed that it is a member of the lipocalin family of proteins that transport small, hydrophobic ligands. Since then, NGAL expression has been reported in several normal tissues where it serves to provide protection against bacterial infection and modulate oxidative stress. Its expression is also dysregulated in several benign and malignant diseases. Its small size, secreted nature and relative stability have led to it being investigated as a diagnostic and prognostic biomarker in numerous diseases including inflammation and cancer. Functional studies, conducted primarily on lipocalin 2 (Lcn2), the mouse homologue of human NGAL have revealed that Lcn2 has a strong affinity for iron complexed to both bacterial siderophores (iron-binding proteins) and certain human proteins like norepinephrine. By sequestering iron-laden siderophores, Lcn2 deprives bacteria of a vital nutrient and thus inhibits their growth (bacteriostatic effect). In malignant cells, its proposed functions range from inhibiting apoptosis (in thyroid cancer cells), invasion and angiogenesis (in pancreatic cancer) to increasing proliferation and metastasis (in breast and colon cancer). Ectopic expression of Lcn2 also promotes BCR-ABL induced chronic myelogenous leukemia in murine models. By transporting iron into and out of the cell, NGAL also regulates iron responsive genes. Further, it stabilizes the proteolytic enzyme matrix metalloprotease-9 (MMP-9) by forming a complex with it, and thereby prevents its autodegradation. The factors regulating NGAL expression are numerous and range from pro-inflammatory cytokines like interleukins, tumor necrosis factor-α and interferons to vitamins like retinoic acid. The purpose of this review article is to examine the expression, structure, regulation and biological role of NGAL and critically assess its potential as a novel diagnostic and prognostic marker in both benign and malignant human diseases.

Endoscopic diagnosis of biliary tract disease

PURPOSE OF REVIEW

Endoscopic diagnosis of biliary disease is challenging due to difficulties in access, visualization, and sampling. Recent advances in endoscopic technology, ancillary diagnostic methods, and our understanding of autoimmune pancreatitis (AIP) and IgG4-related cholangitis (IRC) have led to improvements in the endoscopic diagnosis of pancreaticobiliary disease.

RECENT FINDINGS

Single-operator cholangioscopy overcomes several of the limitations of mother-baby cholangioscopy enhancing the diagnostic accuracy in indeterminate pancreaticobiliary disease. Probe-based confocal laser endomicroscopy has been recently shown to provide a significantly higher accuracy for the diagnosis of malignant biliary strictures than achieved by endoscopic retrograde cholangiopancreatogram and standard tissue acquisition, and has the potential to develop into a useful adjunct method of cholangioscopy. Fluorescence in-situ hybridization increases the sensitivity of routine brush cytology without compromising specificity in patients with indeterminate biliary strictures. The diagnosis of AIP/IRC remains challenging. The recently published international consensus criteria for AIP have included data on the potential diagnostic utility of endoscopic retrograde pancreatogram and endoscopic ampullary biopsies.

SUMMARY

Recent technical advances as well as ancillary diagnostic methods have improved the diagnostic accuracy of conventional endoscopic techniques. Future refinement of endoscopic methods may further improve diagnostic approaches to biliary disease.