Squaraine dyes as fluorescent turn-on sensors for the detection of porcine gastric mucin: A spectroscopic and kinetic study.

Mucin-type glycoproteins are the principal components of mucus which cover all the mucosal surfaces of the human body. The mucus and mucins are essential mediators of the innate immune system, however in the last decades mucins have been identified even as an important class of cancer biomarkers. Luminogenic materials with fluorescence turn-on behavior are becoming promising materials because of their advantages of label free, relatively inexpensive and simple to use properties for biological detection and imaging. Squaraines are luminogens characterized by high fluorescence in organic media but poor emission in aqueous environments due to their tendency to self-aggregate. Herein we investigate the interaction between porcine gastric mucin (PGM) and several squaraines in aqueous media. While squaraine dyes showed low fluorescence intensity and quantum yield in water, as a result of the formation of aggregates, an enhancement of fluorescence up to 45-fold was achieved when PGM was added. PGM was detected in a linear range of 10-300 µg/mL with a limit of detection of 800 ng/mL. The assay was used to quantify mucin in diluted human serum samples and recoveries of 94.9-116.2% were achieved. To the best of our knowledge, this is the easiest and convenient method for mucin detection in the reported literature.

Exploring the potential of mucin 13 (MUC13) as a biomarker for carcinomas and other diseases.

BACKGROUND: Mucin 13 (MUC13) is a cell surface glycoprotein aberrantly expressed in a variety of epithelial carcinomas. Thus far, the role of MUC13 in various diseases remains elusive. To the best of our knowledge, this is the first study to examine the potential of MUC13 as a serum biomarker in a variety of carcinomas and other conditions. METHODS: We developed a recombinant MUC13 protein, mouse monoclonal antibodies and enzyme immunoassay (ELISA) for MUC13. We used this assay to measure MUC13 levels in the supernatants of cancer cell lines and a large cohort of serum samples from healthy and diseased individuals. RESULTS: MUC13 is secreted from cancer cell lines, with highest levels found in ovarian cancer cell lines. MUC13 levels in human sera were significantly increased in patients with renal failure and 20%-30% of patients with ovarian, liver, lung and other cancers. MUC13 was also elevated in 70% of patients with active cutaneous melanoma, but not uveal melanoma. Furthermore, we identified significant MUC13 elevations in the serum of patients with vasculitis (ANCA-positive) autoantibodies, but not in those with inflammatory bowel disease. CONCLUSIONS: Serum MUC13 is frequently elevated not only in a variety of malignant cases but also in some benign pathologies, thus appearing to be a non-specific disease biomarker. Nonetheless, serum MUC13 is clearly highly elevated in some carcinoma patients, and its relationship with tumor progression in this context warrant further research. Future studies that examine the correlation between serum MUC13 levels to stage of cancer could elucidate prognostic potential.

Potential diagnostic and prognostic biomarkers for cholangiocarcinoma in serum and bile.

Cholangiocarcinoma (CCA) is a devastating malignancy that is difficult to treat because of its insensitivity to conventional therapies and the inability to detect early tumor formation. Novel molecular techniques have enabled the use of serum and bile markers for CCA diagnosis and prognosis. Herein, we summarize the principal characteristics of serum and bile markers of CCA. Biomarkers such as interleukin-6, matrix metalloproteinases, serotonin (5-hydroxytryptamine) and bile acids have shown promise for improving CCA diagnosis. Several markers such as CYFRA 21-1, MK-1 and C-reactive protein were recently shown to be effective for CCA prognosis.

Mucins and Cytokeratins as Serum Tumor Markers in Breast Cancer.

Structural and functional characteristics of mucins and cytokeratins are shortly described. Thereafter, those commonly used in breast cancer as serum tumor markers are considered. First CA15.3, MCA, CA549, CA27.29 mucins and CYFRA21.1, TPA, TPS cytokeratins alone or in association have been examined in different stages and conditions. Then their usefulness in monitoring disease-free breast cancer patients is evaluated. The central role of the established cut-off and critical change, the "early" treatment of recurrent disease and the potential benefit in survival are other issues that have been highlighted and discussed. The successive sections and subsections deal with the monitoring of advanced disease. In them, the current recommendations and the principal findings on using the above mentioned mucins and cytokeratins have been reported. A computer program for interpreting consecutive measurements of serum tumor markers also has been illustrated. The final part of the chapter is devoted to mucins and cytokeratins as markers of circulating and disseminated tumor cells and their usefulness for prognosis.

Serum tumor markers in bile duct cancer--a review.

CONTEXT: Bile duct cancer (BDC) is a disease with a very grave prognosis, often diagnosed too late. OBJECTIVE: The aim of this review is to evaluate available literature on tumor markers in serum from patients with BDC. METHODS: Using the search words "serum markers", "bile duct cancer", "cholangiocarcinoma", "biomarker" and "tumor marker", a search was carried out. RESULTS: Seventy-five studies were included in the review. CONCLUSION: CA19-9 is by far the most studied and most promising diagnostic and/or prognostic marker in BDC. But also the different mucins are interesting as new markers of BDC in serum.

Electrochemical immunosensors in breast and ovarian cancer.

During the last decades the incidence of cancer increased dramatically especially in developed countries. In spite of the fact that the immunochemical methods allowed the diagnosis in early stages, the biopsies are generally invasive methods that create discomfort to patients. The need for fast, sensitive, easy to use and noninvasive diagnosis tools is actually of great interest for many research groups all over the world. Immunosensors (ISs) are miniaturized measuring devices, which selectively detect their targets by means of antibodies (Abs) and provide concentration-dependent signals. Ab binding leads to a variation in electric charge, mass, heat or optical properties, which can be detected directly or indirectly by a variety of transducers. A great number of proteins could be considered as recognition element. In this review the attention was focused on main cancer biomarkers, currently used by immunological methods (immunohistochemistry, ELISA, flow cytometry, Western blot, immunofluorescence etc) and in the development of electrochemical immunoassays that could be used in cancer diagnosis, prognosis and therapy monitoring.

Challenging the limits of detection of sialylated Thomsen-Friedenreich antigens by in-gel deglycosylation and nano-LC-MALDI-TOF-MS.

The identification of sialylated Thomsen-Friedenreich antigens in proteins poses much interest in the context of cancer research. MALDI-TOF-MS is a powerful technique for this purpose; still it shows considerable low sensitivity for sialylated molecules due to in-source and metastable decomposition. Herein, we report a target-driven strategy to identify these antigens in minute amounts of glycoproteins isolated in polyacrylamide gels. The glycans were recovered from gel spots by reductive ß-elimination, permethylated and analyzed by nano-LC-MALDI-TOF-MS. A computational algorithm was developed to filter spectral noise and enhance/isolate the signals of interest. Sialylated antigens were identified in minute amounts of fetuin (0.1 µg) and plasminogen (1.0 µg) by this approach.MS assignments were further validated by enzymatic methods. This methodology allowed a fivefold decrease in the current LOD of fetuin sialylated O-glycans by MALDI-TOF-MS.

An improved lectin-based method for the detection of mucin-type O-glycans in biological samples.

Mucins and mucin-type glycoproteins, collectively referred to as mucin-type O-glycans, are implicated in many important biological functions and pathological conditions, including malignancy. Presently, there is no reliable method to measure the total mucin-type O-glycans of a sample, which may contain one or more of these macromolecules of unknown structures. We report the development of an improved microassay that is based on the binding of lectins to the unique and constant GalNAc-Ser/Thr structural feature of mucin-type O-glycans. Since the sugar-amino acid linkage in the mucin-type O-glycans is invariably cryptic, we first chemically removed the heterogeneous peripheral and core saccharides of model glycoconjugates before examining for their interactions using an enzyme-linked lectin assay (ELLA). Desialylation of the model glycoconjugates led to maximal binding of the lectins but additional treatments such as Smith degradation did not result in increased binding. Of the lectins tested for their ability to probe the desialylated O-glycans, jacalin showed the highest sensitivity followed by champedak galactose binding (CGB) lectin and Vicia villosa agglutinin. Further improvement in the sensitivity of ELLA was achieved by using microtiter plates that were pre-coated with the CGB lectin, which increased the specificity of the assay to mucin-type O-glycans. Finally, the applicability of the developed sandwich ELLA to crude samples was demonstrated by estimating trace quantities of the mucin-type O-glycans in the human serum.

Characterization of cancer associated mucin type O-glycans using the exchange sialylation properties of mammalian sialyltransferase ST3Gal-II.

Our previous studies suggest that the α2,3sialylated T-antigen (NeuAcα2,3Galß1,3GalNac-) and associated glycan structures are likely to be elevated during cancer. An easy and reliable strategy to label mucinous glycans that contain such carbohydrates can enable the identification of novel glycoproteins that are cancer associated. To this end, the present study demonstrates that the exchange sialylation property of mammalian ST3Gal-II can facilitate the labeling of mucin glycoproteins in cancer cells, tumor specimens, and glycoproteins in cancer sera. Results show that (i) the radiolabeled mucin glycoproteins of each of the cancer cell lines studied (T47D, MCF7, LS180, LNCaP, SKOV3, HL60, DU4475, and HepG2) is distinct either in terms of the specific glycans presented or their relative distribution. While some cell lines like T47D had only one single sialylated O-glycan, others like LS180 and DU4475 contained a complex mixture of mucinous carbohydrates. (ii) [14C]sialyl labeling of primary tumor cells identified a 25-35 kDa mucin glycoprotein unique to pancreatic tumor. Labeled glycoproteins for other cancers had higher molecular weight. (iii) Studies of [14C] sialylated human sera showed larger mucin glycopeptides and >2-fold larger mucin-type chains in human serum compared to [14C]sialyl labeled glycans of fetuin. Overall, the exchange sialylation property of ST3Gal-II provides an efficient avenue to identify mucinous proteins for applications in glycoproteomics and cancer research.

Identification of blood-protein carriers of the CA 19-9 antigen and characterization of prevalence in pancreatic diseases.

The current best serum marker for pancreatic cancer, CA 19-9, detects a carbohydrate antigen on multiple protein carriers. Better knowledge of the protein carriers of the CA 19-9 antigen in various disease states may lead to improved diagnostic tests. To identify proteins that carry the CA 19-9 antigen, we immunoprecipitated the CA 19-9 antigen from pooled sera and identified the associated proteins using MS. Among the high-confidence identifications, we confirmed the presence of the CA 19-9 antigen on Apolipoprotein B-100 by antibody arrays and Western blot and on kininogen, ARVCF, and Apolipoprotein E by antibody arrays. We characterized the frequency and levels of the CA 19-9 antigen on the four proteins across various patient groups (pancreatic cancer, pancreatitis, and healthy controls) using antibody arrays. Nearly, 10-25% of the subjects showed elevations of the antigen on each protein, but the elevations were not associated with disease state or total CA 19-9 levels. These results contribute to our knowledge of the carrier proteins of an important functional glycan and the rate at which the glycan is displayed. This work also demonstrates a strategy for using the complementary methods of MS and antibody microarrays to identify protein carriers of glycans and assess the diagnostic value of measuring glycans on individual proteins.

Seromic profiling of colorectal cancer patients with novel glycopeptide microarray.

Cancer-associated autoantibodies hold promise as sensitive biomarkers for early detection of cancer. Aberrant post-translational variants of proteins are likely to induce autoantibodies, and changes in O-linked glycosylation represent one of the most important cancer-associated post-translational modifications (PTMs). Short aberrant O-glycans on proteins may introduce novel glycopeptide epitopes that can elicit autoantibodies because of lack of tolerance. Technical barriers, however, have hampered detection of such glycopeptide-specific autoantibodies. Here, we have constructed an expanded glycopeptide array displaying a comprehensive library of glycopeptides and glycoproteins derived from a panel of human mucins (MUC1, MUC2, MUC4, MUC5AC, MUC6 and MUC7) known to have altered glycosylation and expression in cancer. Seromic profiling of patients with colorectal cancer identified cancer-associated autoantibodies to a set of aberrant glycopeptides derived from MUC1 and MUC4. The cumulative sensitivity of the array analysis was 79% with a specificity of 92%. The most prevalent of the identified autoantibody targets were validated as authentic cancer immunogens by showing expression of the epitopes in cancer using novel monoclonal antibodies. Our study provides evidence for the value of glycopeptides and other PTM-peptide arrays in diagnostic measures.

Carbohydrate markers of pancreatic cancer.

Pancreatic cancer is the fourth most common cause of death from cancer in the world and the sixth in Europe. Pancreatic cancer is more frequent in males than females. Worldwide, following diagnosis of pancreatic cancer, <2% of patients survive for 5 years, 8% survive for 2 years and <50% survive for only approx. 3 months. The biggest risk factor in pancreatic cancer is age, with a peak of morbidity at 65 years. Difficulty in the diagnosis of pancreatic cancer causes a delay in its detection. It is one of the most difficult cancers to diagnose and therefore to treat successfully. Additional detection of carbohydrate markers may offer a better diagnosis of pancreatic cancer. Carbohydrate markers of cancer may be produced by the cancer itself or by the body in response to cancer, whose presence in body fluids suggests the presence and growth of the cancer. The most widely used, and best-recognized, carbohydrate marker of pancreatic cancer is CA 19-9 [CA (carbohydrate antigen) 19-9]. However, the relatively non-specific nature of CA 19-9 limits its routine use in the early diagnosis of pancreatic cancer, but it may be useful in monitoring treatment of pancreatic cancer (e.g. the effectiveness of chemotherapy), as a complement to other diagnostic methods. Some other carbohydrate markers of pancreatic cancer may be considered, such as CEA (carcinoembryonic antigen), CA 50 and CA 242, and the mucins MUC1, MUC2 and MUC5AC, but enzymes involved in the processing of glycoconjugates could also be involved. Our preliminary research shows that the activity of lysosomal exoglycosidases, including HEX (N-acetyl-ß-D-hexosaminidase), GAL (ß-D-galactosidase), FUC (α-L-fucosidase) and MAN (α-D-mannosidase), in serum and urine may be used in the diagnosis of pancreatic cancer.

Role of mucins in the skin during benign and malignant conditions.

Skin-related diseases comprise a major health challenge to the practicing physician, and constitute a significant psychological, social and financial burden to the society. Further, skin cancer, especially non-melanoma skin cancer is currently the leading type of malignancy in the Western world. Given the huge burden of skin diseases, there is growing emphasis on understanding their pathophysiology, and towards their early detection. Mucins are high-molecular weight O- and N-linked glycoproteins that have emerged in recent years as important molecules in maintaining health and in promoting or protecting against inflammation and cancer. They have also begun to emerge as highly specific diagnostic and prognostic markers and novel therapeutic targets in several malignant disorders. However, their role in cutaneous pathologies has remained largely obscured. The present review provides the expression patterns and proposed role of mucins in the healthy skin and various benign and malignant skin diseases. The review has immense clinical significance as the availability of highly specific reagents including monoclonal antibodies against mucins makes them extremely attractive targets for specific diagnosis and/or immunotherapy of benign and malignant cutaneous diseases.

Immunomodulation of monocyte-derived dendritic cells through ligation of tumor-produced mucins to Siglec-9.

Dendritic cells (DCs) play an essential role in the induction and maintenance of an effective immune response and express multiple siglecs. In the present study, we investigated whether or not the ligation of tumor-produced mucins with Siglec-9 expressed on immature DCs is related to escape from immunosurveillance in the tumor-bearing state. Expression of Siglec-9 was up-regulated on the development of monocytes into immature DCs and was decreased in mature DCs. Binding of various mucins and artificial glycopolymers carrying poly (NeuAc α2,6 LacNAc) or poly (NeuAc α2,3 LacNAc) to Siglec-9 was demonstrated by means of a plate assay. These mucins also bound to the surface of immature DCs. When immature DCs were treated with LPS in the presence of these mucins or artificial glycopolymers, the production of IL-12 was significantly reduced, but that of IL-10 was not. Furthermore, IL-12 production was decreased to a similar level on treatment with anti-Siglec-9 mAb. Mucins prepared from serum of cancer patients actually could bind to Siglec-9. These results suggest that Siglec-9 expressed on DCs is involved in immunoregulation through ligation with mucins in an epithelial cancer patient.

MUC4 and MUC5AC are highly specific tumour-associated mucins in biliary tract cancer.

Alterations in epithelial mucin expression are associated with carcinogenesis, but there are few data in biliary tract cancer (BTC). In pancreatic malignancy, MUC4 is a diagnostic and prognostic tumour marker, whereas MUC5AC has been proposed as a sensitive serological marker for BTC. We assessed MUC4 and MUC5AC expression in (i) prospectively collected bile and serum specimens from 72 patients with biliary obstruction (39 BTC) by real-time reverse transcriptase-PCR (qPCR) and western blot analysis, and (ii) 79 archived biliary tissues (69 BTC) by immunohistochemistry. In bile, MUC4 protein was detected in 27% of BTC and 29% of primary sclerosing cholangitis (PSC) cases, but not in other benign and malignant biliary diseases (P<0.01 and P=0.06). qPCR revealed a 1.9-fold increased MUC4 mRNA expression in BTC patients' bile compared with benign disease. In archived tissues, MUC4 protein was detected in 37% of BTC but in none of the benign samples (P=0.03). In serum, MUC5AC was found exclusively in BTC and PSC sera (44% and 13%, respectively; P<0.001 for BTC vs non-BTC) and correlated negatively with BTC survival. Biliary MUC4 and serum MUC5AC are highly specific tumour-associated mucins that may be useful in the diagnosis and formulation of therapeutic strategies in BTC.

Serum KL-6 level is elevated in chronic hepatitis C patients with combination therapy of pegylated interferon and ribavirin.

OBJECTIVES: The aim of this study was to evaluate whether or not combination therapy of pegylated interferon (IFN) and ribavirin for chronic hepatitis (CH) C patients enhances the serum level of KL-6, a sensitive marker for interstitial pneumonia. METHODS: CH C patients proven histologically and treated with combination therapy of pegylated IFN-alpha-2b and ribavirin, IFN monotherapy or untreated for 48 weeks were retrospectively selected in chronological order in groups of 25. Serum levels of KL-6 were measured by enzyme-linked immunosorbent assay by use of serum stored at -80 degrees C before and at 12, 24, 36, 48 weeks after the initiation of treatment or follow up. RESULTS: The average serum KL-6 levels in patients treated with combination therapy of pegylated IFN and ribavirin increased by 21% at 12 weeks after the start, 23% at 24 weeks, and 28% at 48 weeks. In patients treated with combination therapy of pegylated IFN and ribavirin, the serum KL-6 level significantly increased during treatment. Patients achieved an elevated serum KL-6 level of more than 450 U/ml with statistical significance when: 1) combination therapy was given (P=0.011), 2) serum KL-6 level pretreatment was high more than 300 U/ml (P=0.014). CONCLUSION: The present study suggests that onset of interstitial pneumonia should be carefully checked in the combination therapy of pegylated-IFN and ribavirin.

[Outcome of patients with acute exacerbation of idiopathic interstitial fibrosis (IPF) treated with sivelestat and the prognostic value of serum KL-6 and surfactant protein D].

Idiopathic interstitial fibrosis (IPF) is a chronic, usually fatal lung disease of unknown etiology. There are few specific therapies for acute exacerbation of IPF and factors predicting the onset or severity of this syndrome are not clearly understood. A neutrophil elastase inhibitor, sivelestat (ONO-5046) has been commercially available in Japan since 2002. This inhibitor has a potent effect in the treatment of ALI/ARDS. To evaluate the outcome of patients with acute exacerbation of IPF treated with sivelestat and estimate prognostic factors, we investigated 10 patients with acute exacerbation of IPF who were intubated and mechanically ventilated. We analyzed the outcome of patients with acute exacerbation of IPF until day 180 and measured the P/F ratio, PEEP levels, the values of peripheral white blood cell number, and C-reactive protein (CRP) on day 0, 3, 7 after admission. Serum KL-6 and surfactant protein D (SP-D) concentration on day 0 were also analyzed. All patients were treated with sivelestat and methylprednisolone (mPSL) pulse therapy for 3 days from day 0 and maintenance therapy with prednisone (0.5 mg/kg/day) were continued. Of the 10 patients. 4 patients had survived (40%) and 6 patients had died (60%) at day 180 from the onset of acute exacerbation of IPF. In survivors, P/F ratio, PEEP levels, and CRP values significantly improved on day 7 (p<0.05). Serum KL-6 and SP-D were lower in survivors on day 0 (p<0.05). Taken together, serum KL-6 and SP-D may prove valuable as biochemical markers of prognosis in acute exacerbation of IPF. Sivelestat may have potential in the treatment of acute exacerbation of IPF.

Circulating thymus- and activation-regulated chemokine/CCL17 is a useful biomarker for discriminating acute eosinophilic pneumonia from other causes of acute lung injury.

BACKGROUND: The presentation of acute eosinophilic pneumonia (AEP) closely resembles that of acute lung injury (ALI)/ARDS, including its idiopathic form, acute interstitial pneumonia (AIP). AEP usually lacks peripheral eosinophilia at the acute phase; therefore, the establishment of serum biomarkers for AEP would be clinically useful. METHODS: We measured the levels of thymus- and activation-regulated chemokine (TARC)/CCL17, eotaxin/CCL11, KL-6, and surfactant protein-D (SP-D) in serum for patients with acute parenchymal lung diseases including AEP (n = 17), AIP (n = 13), pneumonia-associated ALI/ARDS (n = 12), and alveolar hemorrhage (n = 7). To evaluate diagnostic ability, each marker was estimated by measuring the area under the receiver operating characteristic curve (AUC). RESULTS: Serum TARC/CCL17 levels of AEP patients were much higher than those of patients in other disease groups. More importantly, high circulating TARC/CCL17 levels were observed in AEP even at acute phase when peripheral eosinophilia was absent. TARC/CCL17 showed the largest AUC, and the TARC/CCL17 levels with cutoff points from 6,259 to 7,039 pg/mL discriminated AEP from other syndromes with sensitivity and specificity of 100%. The KL-6 level was low in most patients with AEP, and the sensitivity was 81.6% in cutoff with 100% specificity. The AUC for eotaxin/CCL11 and SP-D was small, with values of 0.73 (95% confidence interval [CI], 0.60 to 0.86) and 0.53 (95% CI, 0.31 to 0.64), respectively. CONCLUSIONS: This study indicates that the measurement of circulating TARC/CCL17 and KL-6 is useful for discriminating AEP from other causes of ALI.

Peripheral T-cell lymphoma with diffuse pulmonary infiltration and an increase in serum KL-6 level.

Peripheral T-cell lymphoma is a subtype of non-Hodgkin's lymphoma. A case of peripheral T-cell lymphoma showing diffuse pulmonary involvement together with a marked increase in the level of serum KL-6 is presented. CXR and CT revealed reticular and ground-glass opacities, which mimicked interstitial pneumonia. Immunopathological findings and an analysis of T-cell receptor gene rearrangements of the lung biopsy specimen led to a definite diagnosis of peripheral T-cell lymphoma. In addition, the extensive proliferation of type II pneumocytes, which stained strongly positive for anti-KL-6 antibody suggested that the pneumocytes were the source of serum KL-6.