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Vitronectin is a glycoprotein present in plasma and the extracellular matrix that is implicated in cell migration. The high amount of vitronectin found in neuroblastoma biopsies has been associated with poor prognosis. Moreover, increased vitronectin levels have been described in the plasma of patients with different cancers. Our aim was to assess vitronectin as a potential circulating biomarker of neuroblastoma prognosis. Vitronectin concentration was quantified using ELISA in culture media of four neuroblastoma cell lines grown in a monolayer and in 3D models, and in the plasma of 114 neuroblastoma patients. Three of the neuroblastoma cell lines secreted vitronectin to culture media when cultured in a monolayer and 3D models. Vitronectin release was higher by neuroblastoma cells cultured in 3D models than in the monolayer and was still elevated when cells were grown in 3D scaffolds with cross-linked vitronectin. Vitronectin secretion occurred independently of cell numbers in cultures. Its concentration in the plasma of neuroblastoma patients ranged between 52.4 and 870 µg/mL (median, 218 µg/mL). A ROC curve was used to establish a cutoff of 361 µg/mL, above which patients over 18 months old had worse prognosis ( p = 0.0018). Vitronectin could be considered a new plasma prognostic biomarker in neuroblastoma and warrants confirmation in collaborative studies. Drugs inhibiting vitronectin interactions with cells and/or the extracellular matrix could represent a significant improvement in survival for neuroblastoma patients.

Background: This study aimed to evaluate the relationship of serum vitronectin and integrin alpha V beta 3 (αvβ3) levels with various clinicopathological parameters of breast cancer and to assess the diagnostic value of these markers alone or in combination with the conventional breast cancer biomarker CA15.3., Methods: This study included 50 early diagnosed stage I - II primary breast cancer patients, 20 patients with fibroadenoma benign lesions, and 20 apparently normal healthy controls. Integrin αVβ3, vitronectin, and CA15.3 levels were measured using ELISA technique., Results: Serum levels of integrin αVβ3 and vitronectin were significantly higher in the malignant group than those in the benign group and the control group with (p < 0.001). Significant positive correlation between integrin αvβ3 and vitronectin concentrations was found. Both markers showed significant statistically difference with lymph node, histological grade, tumor stage, and tumor size (p < 0.05). Integrin αvβ3 exhibited the highest sensitivity (70%) and specificity (68%), then vitronectin with 67% and 68%, respectively, followed by CA15.3 showing the least sensitivity and specificity (65% and 62%, respectively). All assessed parameters revealed comparable area under the receiver-operating characteristic curve (AUC) 95% confidence interval (CI) range of 0.581 - 0.822., Conclusions: Integrin αvβ3 is a promising biomarker alone or in combination with vitronectin and CA15.3 for diagnosis and prognosis of early stage breast cancer.

The N-glycosylation of proteins is one of the most important post-translational modifications relevant to various biological functions. The identification and quantification of N-glycoproteins in liquid chromatography-mass spectrometry (LC-MS) is challenging because of their low analytical sensitivity and selectivity. This is due to their microheterogeneity and the difficulty of synthesizing N-glycopeptides as an internal standard. Parallel reaction monitoring (PRM) is widely used in targeted LC-MS. The key advantage of LC-PRM is that it can identify N-glycopeptides using tandem mass spectrometry (MS/MS) fragmentation, even without an internal standard. We investigated the feasibility of analyzing N-glycoproteins using multiplex immunoprecipitation to improve sensitivity and selectivity. We targeted N-glycoproteins [α-fetoprotein (AFP), vitronectin (VTN), and α-1-antichymotrypsin (AACT)] that are abnormally glycosylated in hepatocellular carcinoma (HCC). Their tryptic N-glycopeptides were selected to determine the percentages of fucosylated N-glycopeptides using Y ions, which include glycopeptide fragments with amino acid sequences. Finally, we confirmed that the area under the receiver operating characteristic curve (AUC = 0.944) for the combination of AFP and VTN increased more so than for a single glycopeptide (AUC = 0.889 for AFP and 0.792 for VTN) with respect to discriminating between HCC and cirrhosis serum. This study shows that an LC-PRM method using multiplex N-glycoproteins immunoprecipitated from serum could be applied to develop and verify cancer biomarkers. Graphical abstract.

Like many cancers, an early diagnosis of melanoma is fundamental to ensure a good prognosis, although an important proportion of stage I-II patients may still develop metastasis during follow-up. The aim of this work was to discover serum biomarkers in patients diagnosed with primary melanoma that identify those at a high risk of developing metastasis during the follow-up period. Proteomic and mass spectrophotometry analysis was performed on serum obtained from patients who developed metastasis during the first years after surgery for primary tumors and compared with that from patients who remained disease-free for more than 10 years after surgery. Five proteins were selected for validation as prognostic factors in 348 melanoma patients and 100 controls by ELISA: serum amyloid A and clusterin; immune system proteins; the cell adhesion molecules plakoglobin and vitronectin and the antimicrobial protein dermcidin. Compared to healthy controls, melanoma patients have high serum levels of these proteins at the moment of melanoma diagnosis, although the specific values were not related to the histopathological stage of the tumors. However, an analysis based on classification together with multivariate statistics showed that tumor stage, vitronectin and dermcidin levels were associated with the metastatic progression of patients with early-stage melanoma. Although melanoma patients have increased serum dermcidin levels, the REPTree classifier showed that levels of dermcidin <2.98 μg/ml predict metastasis in AJCC stage II patients. These data suggest that vitronectin and dermcidin are potent biomarkers of prognosis, which may help to improve the personalized medical care of melanoma patients and their survival., (© 2016 UICC.)

Background: Vitronectin (VN) might be involved in the progression of hepatocellular carcinoma (HCC)., Objective: This study was designed to evaluate the diagnostic and prognostic value of serum vitronectin among HCC patients., Methods: A total of 105 patients with HCC, 91 with liver cirrhosis, 102 with chronic hepatitis, and 100 healthy subjects were recruited. Serum VN and alpha-fetoprotein (AFP) levels were measured., Results: Serum VN levels were significantly higher in HCC patients than in the other groups. Based on area under receiver operating characteristic curve, serum VN had similar diagnostic value, compared with serum AFP, in distinguishing HCC from the groups, and also improved the diagnostic value of AFP alone. Serum VN levels were associated with the degree of histological differentiation, multiple foci, vascular tumor thrombosis and tumor node metastasis stage. Serum VN was an independent predictor for early recurrence and disease-free survival. Moreover, serum VN possessed similar prognostic predictive performance as compared to serum AFP and also significantly enhanced the prognostic value of AFP alone., Conclusions: Elevated serum VN levels represented high diagnostic value and had close relation to clinicopathological factors and early recurrence, suggesting that serum VN might be a useful diagnostic and prognostic marker for HCC.

Breast cancer is the most common cancer in women worldwide, identification of new biomarkers for early diagnosis and detection will improve the clinical outcome of breast cancer patients. In the present study, we determined serum levels of vitronectin (VN) in 93 breast cancer patients, 30 benign breast lesions, 9 precancerous lesions, and 30 healthy individuals by enzyme-linked immunosorbent assays. Serum VN level was significantly higher in patients with stage 0-I primary breast cancer than in healthy individuals, patients with benign breast lesion or precancerous lesions, as well as those with breast cancer of higher stages. Serum VN level was significantly and negatively correlated with tumor size, lymph node status, and clinical stage (p < 0.05 in all cases). In addition, VN displayed higher area under curve (AUC) value (0.73, 95 % confidence interval (CI) [0.62-0.84]) than carcinoembryonic antigen (CEA) (0.64, 95 % CI [0.52-0.77]) and cancer antigen 15-3 (CA 15-3) (0.69, 95 % CI [0.58-0.81]) when used to distinguish stage 0-I cancer and normal control. Importantly, the combined use of three biomarkers yielded an improvement in receiver operating characteristic curve with an AUC of 0.83, 95 % CI [0.74-0.92]. Taken together, our current study showed for the first time that serum VN is a promising biomarker for early diagnosis of breast cancer when combined with CEA and CA15-3.

Background: The current methods available for screening and detecting hepatocellular carcinoma (HCC) have insufficient sensitivity and specificity, and only a low percentage of diagnosis of small tumours is based on these assays. Because HCC is usually asymptomatic at potentially curative stages, identification of biomarkers for the early detection of HCC is essential to improve patient survival., Aim: The aim of this study was to identify candidate markers for HCC development in the plasma from hepatitis C virus (HCV)-infected cirrhotic patients., Methods: We compared protein expression profiles of plasma samples from HCV-infected cirrhotic patients with and without HCC, using two-dimensional fluorescence difference gel electrophoresis (2-D DIGE) coupled with MALDI-TOF/TOF mass spectrometry. The 2-D DIGE results were analysed statistically using Decyder™ software, and verified by western blot and enzyme-linked immunosorbent assay (ELISA)., Results: In the plasma of HCV-infected HCC patients, we observed decreased expression of complement component 9, ficolin-3 (FCN3), serum amyloid P component (SAP), fibrinogen-gamma and immunoglobulin gamma-1 chain, and increased expression of vitronectin (VTN) and galectin-3 binding protein (G3BP) by DIGE analysis. ELISA confirmed DIGE results for VTN and G3BP but not for SAP or FCN3 in a larger patient population., Conclusions: The proteins VTN and SAP are candidate biomarkers for HCC development in HCV-infected cirrhotic patients., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

A simple mass spectrometric approach for the discovery and validation of biomarkers in human plasma was developed by targeting nonglycosylated tryptic peptides adjacent to glycosylation sites in an N-linked glycoprotein, one of the most important biomarkers for early detection, prognoses, and disease therapies. The discovery and validation of novel biomarkers requires complex sample pretreatment steps, such as depletion of highly abundant proteins, enrichment of desired proteins, or the development of new antibodies. The current study exploited the steric hindrance of glycan units in N-linked glycoproteins, which significantly affects the efficiency of proteolytic digestion if an enzymatically active amino acid is adjacent to the N-linked glycosylation site. Proteolytic digestion then results in quantitatively different peptide products in accordance with the degree of glycosylation. The effect of glycan steric hindrance on tryptic digestion was first demonstrated using alpha-1-acid glycoprotein (AGP) as a model compound versus deglycosylated alpha-1-acid glycoprotein. Second, nonglycosylated tryptic peptide biomarkers, which generally show much higher sensitivity in mass spectrometric analyses than their glycosylated counterparts, were quantified in human hepatocellular carcinoma plasma using a label-free method with no need for N-linked glycoprotein enrichment. Finally, the method was validated using a multiple reaction monitoring analysis, demonstrating that the newly discovered nonglycosylated tryptic peptide targets were present at different levels in normal and hepatocellular carcinoma plasmas. The area under the receiver operating characteristic curve generated through analyses of nonglycosylated tryptic peptide from vitronectin precursor protein was 0.978, the highest observed in a group of patients with hepatocellular carcinoma. This work provides a targeted means of discovering and validating nonglycosylated tryptic peptides as biomarkers in human plasma, without the need for complex enrichment processes or expensive antibody preparations.

Purpose: Breast cancer is the most frequent malignancy in women. However, no useful serum markers with high sensitivity and specificity for the detection of early breast cancer have been identified. The search for biological markers of early breast cancer is of continual interest in experimental and clinical breast cancer research. We recently described a simple and highly reproducible three-step proteome analysis for identifying potential disease-marker candidates among the low-abundance serum proteins., Methods: Serum samples from breast ductal carcinoma in situ (DCIS) patients and normal controls were subjected to a three-step serum proteome analysis. The steps were the following: first, immunodepletion of most abundant proteins; second, fractionation using reverse-phase high-performance liquid chromatography; and third, separation using two-dimensional electrophoresis (2-DE). Differences revealed by protein staining were further confirmed by Western blotting, immunohistochemical staining, and enzyme-linked immunosorbent assays (ELISA)., Results: Twenty-two upregulated and 26 downregulated spots were detected on the 2-DE gels, and a total of 33 proteins were identified by liquid chromatography and tandem mass spectrometry. Western blotting confirmed that the level of vitronectin was significantly increased in DCIS patients compared with that of normal controls. Immunohistochemical staining of vitronectin in breast cancer tissue revealed high expression in small vessel walls surrounding cancer cells and the extracellular matrix of stroma. Moreover, vitronectin serum concentrations, as measured by ELISA, were significantly increased in patients with DCIS or more advanced breast cancer compared with those of normal controls., Conclusions: Vitronectin could serve as a promising serum marker for the detection of primary breast cancer.

Stable isotope dilution-multiple reaction monitoring-mass spectrometry (SID-MRM-MS), which is an alternative to immunoassay methods such as ELISA and Western blotting, has been used to alleviate the bottlenecks of high-throughput verification of biomarker candidates recently. However, the inconvenience and high isotope consumption required to obtain stably labeled peptide impedes the broad application of this method. In our study, the (18)O-labeling method was introduced to generate stable isotope-labeled peptides instead of the Fmoc chemical synthesis and Qconcat recombinant protein synthesis methods. To make (18)O-labeling suitable for absolute quantification, we have added the following procedures: (1) RapiGest SF and microwave heating were added to increase the labeling efficiency; (2) trypsin was deactivated completely by chemical modification using tris(2-carboxyethyl)phosphine (TCEP) and iodoacetamide (IAA) to prevent back-exchange of (18)O to (16)O, and (3) MRM parameters were optimized to maximize specificity and better distinguish between (18)O-labeled and unlabeled peptides. As a result, the (18)O-labeled peptides can be prepared in less than 1 h with satisfactory efficiency (>97%) and remained stable for 1 week, compared to traditional protocols that require 5 h for labeling with poor stability. Excellent separation of (18)O-labeled and unlabeled peptides was achieved by the MRM-MS spectrum. Finally, through the combined improvement in (18)O-labeling with multiple reaction monitoring, an absolute quantification strategy was developed to quantitatively verify hepatocellular carcinoma-related biomarker candidates, namely, vitronectin and clusterin, in undepleted serum samples. Sample preparation and capillary-HPLC analysis were optimized for high-throughput applications. The reliability of this strategy was further evaluated by method validation, with accuracy (%RE) and precision (%RSD) of less than 20% and good linearity (r(2) > 0.99), and clinical validation, which were consistent with previously reported results. In summary, our strategy can promote broader application of SID-MRM-MS for biomarkers from discovery to verification regarding the significant advantages of the convenient and flexible generation of internal standards, the reduction in the sample labeling steps, and the simple transition.

Changes in N-linked glycan structures are related to the initiation and progression of hepatocellular carcinoma (HCC), one of the most common fatal cancers worldwide. In this study, we describe a simple and an efficient strategy for the selective identification and quantitation of N-linked glycoproteins that does not require extensive enrichment steps prior to MS/MS analysis. With this approach, N-linked glycoprotein differences between the plasma of healthy and HCC patients were selectively quantified after iTRAQ labeling. We identified a total of 14 N-linked glycopeptides with higher expression in HCC patient plasma than in healthy controls (>or=1.5 fold). Additionally, we characterized alterations in the glycan structures of vitronectin (Asn-169, 242) and antithrombin III (Asn-225) that were identified in HCC patient plasma. The intact glycopeptides with native glycan structures were also elevated in HCC tumor tissue. Taken together, these data support the utility of our approach for high throughput global profiling and quantification of the N-linked glycopeptides to identify disease biomarkers.

Surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF MS) is a proteomic technique that enables the profiling of proteins present in any biological material studied. We used this approach to identify new biomarkers of hepatocellular carcinoma (HCC) in the sera of patients with cirrhosis. Sera from 82 patients with cirrhosis, either without (n = 38) or with (n = 44) HCC, were analyzed by SELDI-TOF MS, and the results of the two groups were compared. The most efficient protein peaks leading to discrimination of patients with HCC were selected (receiver operative characteristic curves). The highest-scoring peak combination was established in a first group of serum samples (multinomial regression) and was tested in an independent group. The protein corresponding to the highest discrimination was purified and characterized further. The intensity of 30 protein peaks significantly differed between cirrhotic patients with and without HCC. An algorithm including the six highest-scoring peaks allowed correct classification (presence or absence of HCC) of 92.5% of patients in the test sample set and 90% in the validation sample set. The highest discriminating peak (8900 Da) was purified further and was characterized as the C-terminal part of the V10 fragment of vitronectin. An in vitro study suggested that the increase of the 8900-Da fragment in the serum of patients with HCC may proceed from the cleavage of native vitronectin with metalloproteases, a family of enzymes whose activity is enhanced in HCC. In conclusion, global protein profiling is an efficient approach that enabled us to identify a catalytic fragment ofvitronectin as a new serum marker of HCC in patients with chronic liver diseases.