Surface glycoproteomic analysis of hepatocellular carcinoma cells by affinity enrichment and mass spectrometric identification

Cell surface glycoproteins are one of the most frequently observed phenomena correlated with malignant growth. Hepatocellular carcinoma (HCC) is one of the most malignant tumors in the world. The majority of hepatocellular carcinoma cell surface proteins are modified by glycosylation in the process of tumor invasion and metastasis. Therefore, characterization of cell surface glycoproteins can provide important information for diagnosis and treatment of liver cancer, and also represent a promising source of potential diagnostic biomarkers and therapeutic targets for hepatocellular carcinoma. However, cell surface glycoproteins of HCC have been seldom identified by proteomics approaches because of their hydrophobic nature, poor solubility, and low abundance. The recently developed cell surface-capturing (CSC) technique was an approach specifically targeted at membrane glycoproteins involving the affinity capture of membrane glycoproteins using glycan biotinylation labeling on intact cell surfaces. To characterize the cell surface glycoproteome and probe the mechanism of tumor invasion and metastasis of HCC, we have modified and evaluated the cell surface-capturing strategy, and applied it for surface glycoproteomic analysis of hepatocellular carcinoma cells. In total, 119 glycosylation sites on 116 unique glycopeptides were identified, corresponding to 79 different protein species. Of these, 65 (54.6?%) new predicted glycosylation sites were identified that had not previously been determined experimentally. Among the identified glycoproteins, 82?% were classified as membrane proteins by a database search, 68?% had transmembrane domains (TMDs), and 24?% were predicted to contain 2-13 TMDs. Moreover, a total of 26 CD antigens with 50 glycopeptides were detected in the membrane glycoproteins of hepatocellular carcinoma cells, comprising 43?% of the total glycopeptides identified. Many of these identified glycoproteins are associated with cancer such as CD44, CD147 and EGFR. This is a systematic characterization of cell surface glycoproteins of HCC. The membrane glycoproteins identified in this study provide very useful information for probing the mechanism of liver cancer invasion and metastasis.     

Fine needle aspiration biopsy of hepatocellular carcinoma and hepatocellular nodular lesions: role,controversies and approach to diagnosis

A. Wee
Fine needle aspiration biopsy of hepatocellular carcinoma and hepatocellular nodular lesions: role, controversies and appr oach to diagnosis The role of fine needle aspiration (FNA) biopsy of the liver has evolved. Advances in imaging modalities have obviated the need for tissue confirmation in clinically classic hepatocellular carcinoma (HCC). The risks of needle tract seeding and haematogenous dissemination have been actively debated. Nowadays, cytopathologists are confronted by smaller and smaller nodules, detected due to increased surveillance of high‐risk cirrhotic patients. Tissue characterization of small well‐differentiated hepatocellular nodular lesions (size less than and equal to 2 cm) is extremely challenging and has therapeutic implications. Major issues in the cytodiagnosis of HCC include: (i) distinguishing benign hepatocellular nodular lesions, namely, large regenerative nodules, dysplastic nodules, focal nodular hyperplasia and hepatocellular adenoma from reactive hepatocytes; (ii) distinguishing well‐differentiated HCC from benign hepatocellular nodular lesions; (iii) distinguishing poorly differentiated HCC from intrahepatic cholangiocarcinoma and metastatic carcinomas; (iv) determining the histogenesis of a malignant tumour; and (v) determining the site of origin of a malignant tumour. An overview of the biological evolution and histopathological aspects of dysplastic nodules, small HCCs and ‘nodule‐in‐nodule’ lesions is presented in tandem with clinically relevant nomenclature. An algorithmic approach to FNA diagnosis of HCC and hepatocellular nodular lesions is outlined. Optimal results depend on (i) a dedicated radiologist‐cytopathologist team; (ii) an on‐site cytology service, (iii) a combined cytohistological approach, (iv) immunohistochemistry, and (v) clinicopathological correlation. As we move towards personalized medicine, it is envisaged that hepatic FNA is likely to become a point of care in the management protocol as it takes on the additional role of procurement of tumour and peritumoural tissues for genomic and proteomic profiling to enable targeted molecular therapy.     

Pattern analysis of serum alpha-fetoprotein in the early diagnosis of hepatocellular carcinoma in liver cirrhosis

In a surveillance program for hepatocellular carcinoma (HCC), serum alpha-fetoprotein (AFP) was determined every 4 months in 164 patients with liver cirrhosis. Ultrasonography (US) was performed yearly or as dictated by abnormal AFP levels. During a follow-up of 32.5 +/- 20.8 months HCC was identified by US in 16 patients. In 9 of them the AFP levels rose steadily over 4 months, increasing 7, 8 and 12 months in 3 cases before the lesion became detectable by US. In 4 patients tumors developed despite persistently normal AFP levels. Nine more patients showed abnormal fluctuations of AFP but HCC was not detected. AFP sensitivity was higher at a low cut-off point (40 ng/ml) while specificity of the test appeared higher at the 200 ng/ml cut-off point. An AFP value rising steeply over a few months appeared more reliable than a fixed preset threshold in indicating carcinomatous transformation. Screening for AFP can be expected to uncover about 3/4 of HCC developing in cirrhotics with few false-positive reactions. The test may have a unique role in identifying a subset of liver tumors whose early expression is AFP production.     

Expression of serum miR-221 in human hepatocellular carcinoma and its prognostic significance

Objective

To investigate whether the serum miR-221 expression correlates with clinicopathologic features and the prognosis of hepatocellular carcinoma (HCC) patients.

Methods

Four miRNAs (miR-221, miR-222, miR-21 and miR-224) related to HCC were selected in the present study. Serum miRNA expression was investigated in 46 HCC patients and 20 healthy normal controls by using real-time PCR technique, and then correlations between miR-221 expression and the clinicopathological features and prognosis of HCC patients were evaluated.

Results

The four miRNAs were found to be differentially overexpressed in HCC serum samples, and high level of miR-221 expression was correlated with tumor size (P < 0.001), cirrhosis (P = 0.003) and tumor stage (P = 0.016). In addition, Kaplan–Meier survival analysis showed that the overall survival rate of the high miR-221 expression group (27.6%) was significantly lower than that of the low miR-221 expression group (62.3%, P < 0.05).

Conclusions

Serum miR-221, upregulated in HCC, can provide predictive significance for prognosis of HCC patients.     

Elucidation of N-glycosylation sites on human platelet proteins: a glycoproteomic approach

Among known platelet proteins, a prominent and functionally important group is represented by glycoprotein isoforms. They account e.g. for secretory proteins and plasma membrane receptors including integrins and glycoprotein VI as well as intracellular components of cytosol and organelles including storage proteins (multimerin 1 etc.). Although many of those proteins have been studied for some time with regard to their function, little attention has been paid with respect to their glycosylation sites. Here we report the analysis of N-glycosylation sites of human platelet proteins. For the enrichment of glycopeptides, lectin affinity chromatography as well as chemical trapping of protein bound oligosaccharides was used. Therefore, concanavalin A was used for specific interaction with carbohydrate species along with periodic acid oxidation and hydrazide bead trapping of glycosylated proteins. Derivatization by peptide:N-glycosidase F yielded deglycosylated peptides, which provided the basis for the elucidation of proteins and their sites of modification. Using both methods in combination with nano-LC-ESI-MS/MS analysis 70 different glycosylation sites within 41 different proteins were identified. Comparison with the Swiss-Prot database established that the majority of these 70 sites have not been specifically determined by previous research projects. With this approach including hydrazide bead affinity trapping, the immunoglobulin receptor G6f, which is known to couple to the Ras-mitogen-activated protein kinase pathway in the immune system, was shown here for the first time to be present in human platelets.     

Altered glycosylation,expression of serum haptoglobin and alpha-1-antitrypsin in chronic hepatitis C,hepatitis C induced liver cirrhosis and hepatocellular carcinoma patients

Liver cirrhosis with hepatitis C viral infection (HCV-LC) causes high risk to develop hepatocellular carcinoma (HCC). Besides diagnosis of liver cirrhosis by biochemical test, imaging techniques, assessment of structural liver damage by biopsy shows several disadvantages. Our aim was to monitor the changes in the expression level of serum proteins and their glycosylation pattern among chronic hepatitis C (HCV-CH), HCV-LC and HCC patients with respect to controls. 2D gel electrophoresis of HCV-CH, HCV-LC and HCC patients’ sera showed several protein spots, which were identified by LC-MS. The change in the expression of two prominent protein spots, haptoglobin (Hp) and alpha 1-antitrypsin (AAT) was evaluated by western blot and ELISA. The changes in glycosylation pattern of these serum proteins were assayed using different lectins. Increased level of Hp and AAT was observed in HCV-LC and HCC patients’ group whereas those were found to be present less in HCV-CH patient groups with respect to control as determined by ELISA using monoclonal antibodies. Decreased level of sialylation in both Hp and AAT was observed in HCV-LC and HCV-CH patients’ group whereas increased level of sialylation was observed in HCC patient groups by ELISA using Sambucus nigra agglutinin. On the other hand increased level of fucosylation in two serum glycoproteins was observed in HCV-LC and HCC patients’ group using Lens culinarris agglutinin. High glycan branching was found in HCV-LC and HCC patient groups in Hp but not in HCV-CH as determined by Datura stramonium agglutinin. However, there was no such change observed in glycan branching in AAT of HCV-CH and HCV-LC patients’ groups, to the contrary high glycan branching was observed in HCC patients’ group. Increased level of exposed galactose in both serum proteins was observed in both HCC patients’ group as determined by Ricinus communis agglutinin. The present glycoproteomics study could predict the progression of HCV-CH, HCV-LC and HCC without the need of liver biopsy.     

The diagnostic value of serum DSA-TRF in hepatocellular carcinoma

TRF is a glycoprotein mainly secreted by hepatocytes, The aim of this study was to explore the diagnostic value of aberrant glycosylated serum transferrin (TRF) especially containing multi-antennary glycans in hepatocellular carcinoma (HCC).A total of 581 subjects including HCC patients, liver cirrhosis (LC) patients, chronic hepatitis (CHB) patients and healthy controls (HC) were recruited. All the subjects were randomly assigned to training group (n?=?411) and validation group (n?=?170). We firstly analyzed the serum protein N-glycome profiling of HCC, LC, and HC by DNA sequencer–assisted fluorophore-assisted carbohydrate electrophoresis (DSA-FACE) technology. We established a lectin-antibody sandwich ELISA (Lectin-ELISA) method to detect multi-antennary glycans-contained TRF (DSA-TRF) in serum, in which Datura stramonium Agglutinin (DSA) was used for specific recognition. Levels of serum DSA-TRF and TRF were analyzed respectively. The diagnostic efficacies of DSA-TRF and TRF of differentiating HCC patients from CHB, LC patients and HC within the training group were evaluated using receiver operating characteristic (ROC) curve and tested in the validation group.The result found that in training group, serum TRF and DSA-TRF levels differed significantly between HCC (1.86?±?0.50, g/L, 0.285?±?0.06), CHB?+?LC (2.39?±?0.74, g/L, 0.189?±?0.07) and HC (1.92?±?0.69, g/L, 0.249?±?0.09) (HCC vs. CHB?+?LC, P?<?0.001; HCC vs. HC, P?<?0.001; CHB?+?LC vs. HC, P?<?0.001). The area under the ROC curve (AUC) of DSA-TRF was significantly superior to AFP (0.880, 95%CI: 0.834–0.925 vs. 0.776, 95%CI: 0.725–0.827, P?=?0.003) in differentiating HCC from CHB?+?LC. The AUC of diagnostic model GlycoTRF1 (0.981, 95%CI: 0.969–0.993) was higher than DSA-TRF and AFP alone (P<0.001) in differentiating HCC from CHB?+?LC, which was verified in validation group.The results indicated that the serum DSA-TRF might serve as a potential glycan biomarker for distinguishing HCC from CHB and LC.

     

甲胎蛋白在肝癌的诊断和治疗中的研究进展

肝细胞癌(Hepatocellular carcinoma,HCC)是致死率第3的恶性肿瘤,也是全球第5大常见癌症。肝癌在临床上的治疗手段非常有限,患者的总生存率也很低。因此,肝癌的早期诊断和治疗对于患者总生存率有着重要的影响。甲胎蛋白(Alpha-fetoprotein,AFP)是最早发现也是目前应用最广泛的肝癌标志物之一。目前,多项研究表明,作为一个特异性的癌基因,AFP在肝癌的发生、发展、诊断和治疗中有巨大的研究价值。文中简述了AFP在肝癌发生发展中的分子调控机制以及在肝癌细胞逃避免疫监视中的作用,着重阐述AFP作为重要的肝癌靶标分子在肝癌的临床诊断和治疗研究中的应用。     

肠道微生态在肝癌诊疗应用中的研究进展

肠道微生态是由数量巨大且结构复杂的肠道菌群与肠黏膜屏障组成,参与机体多种重要生理功能,与多种疾病密切相关。由于肠道与肝脏有着密切而特殊的关系,肠道微生态可通过肠―肝循环及其与宿主的相互作用来调节肝脏疾病的进展。肠道微生态失调与肝癌进展密切相关,肠道中关键功能菌可作为肝癌早期预防、诊断和治疗的新的预测标记物与新的治疗靶点。本文将对肠道微生态在肝癌发病机制中的作用以及基于肠道微生态理论的多种肝癌防治策略进行综述。     

Comparative diagnostic efficacy of serum squamous cell carcinoma antigen in hepatocellular carcinoma

ABSTRACT: Hepatocellular carcinoma (HCC) is a common liver malignancy in Nigeria. Hepatitis B and C viruses, alcohol and Aflatoxin B are among the various aetiology. More work needs to be done in the search for markers that will aid early detection of this condition as it is uniformly fatal once advanced. Alphafetoprotein (AFP) remains the most widely used tumour marker of HCC detection in spite of its known shortcomings. The objective of this study was to determine the efficacy of serum squamous cell carcinoma antigen (SCCA) , in comparison to alphafetoprotein in the detection of HCC. METHOD: Sixty patients with HCC and thirty apparently healthy controls attending the Medical Outpatient Department(MOPD) of the University College Hospital Ibadan(UCH) Nigeria were selected for the study. Questionnaire was used to collect clinical data while AFP, SCCA levels,serum HBsAg and anti-HCV were determined using ELISA method- ( Diagnostic Automation Inc. Canada),Abdominal ultrasound scan was also done. Result:Thirty one(51.7%) out of 60 selected cases were positive for HBsAg while six(20%) out of 30 controls were positive for HBsAg(p= 0.004) .Out of the 60 cases selected for this study only 2 (3.3.%) cases were positive for hepatitis C virus, while only 1(3.3%) out of 30 control was positive for hepatitis C virus(p= 0.74). The mean AFP value for cases with HCC was 393.21ng/ml +/-386.97 compared to the control group which was 5.60 +/- 13.03 ng/ml (P value 0.001).The mean SCCA level was 0.64 +/- 0.56ng/ml and 0.71+/-0.65ng/ml for cases and controls respectively (p=0.631) CONCLUSION: Alphafetoprotein remains a good tumour marker for the diagnosis of HCC. Serum squamous cell carcinoma antigen(SCCA) has no discriminatory power and may not be useful as a tumour marker for Nigerians with hepatocellular carcinoma.     

Carbohydrate-based measurements on alpha-fetoprotein in the early diagnosis of hepatocellular carcinoma

Serum alpha-fetoprotein (AFP) is a useful marker for the diagnosis of hepatocellular carcinoma (HCC), although this protein also increases moderately in benign liver diseases. The serum concentration of AFP in HCC at the time of initial diagnosis is now lower than before because of advancements in techniques for imaging the liver. The AFP concentration alone cannot distinguish between HCC and benign liver diseases, especially when it is less than 1000 ng ml^–1. These circumstances lead to the need to discriminate between these diseases. This has been achieved by determining the carbohydrate structures of AFP by its reactivity withLens culinaris agglutinin (LCA). The percentage of LCA-reactive species of AFP is significantly higher in HCC than in benign liver diseases. The fucosylation of the sugar chain at the innermostN-acetylglucosamine is the molecular basis of this variation. Therefore, the term fucosylation index has been introduced to express the percentage of LCA-reactive species of AFP. This index is useful for the diagnosis of HCC even if the carcinoma is at an early stage. Furthermore, it can predict the development of HCC in the follow-up of chronic liver diseases. Thus, the qualitative and quantitative measurements of carbohydrate in AFP provide us with very valuable information for the differential diagnosis of various liver diseases.     

Fucosylation of serum alpha-fetoprotein in patients with primary hepatocellular carcinoma

alpha-Fetoprotein specimens were prepared from the sera of four patients with hepatocellular carcinoma. The lentil lectin-reactive and lectin-nonreactive variants of this glycoprotein were also prepared from the serum of one of the four patients by affinity chromatography with immobilized lectin. The correlation between the carbohydrate structure of these compounds and their reactivity in crossed immuno-affinoelectrophoresis with lentil lectin was studied by chemical analysis and affinity chromatography of the glycopeptides with lectin columns. It was found that the lentil lectin-reactive variant contained a carbohydrate chain of the fucosylated biantennary complex type. These data together with previous findings indicate that most of the patients with hepatocellular carcinoma have an elevated serum concentration of fucosylated alpha-fetoprotein.     

Galectin-1-binding glycoforms of haptoglobin with altered intracellular trafficking, and increase in metastatic breast cancer patients

Sera from 25 metastatic breast cancer patients and 25 healthy controls were subjected to affinity chromatography using immobilized galectin-1. Serum from the healthy subjects contained on average 1.2 mg per ml (range 0.7-2.2) galectin-1 binding glycoproteins, whereas serum from the breast cancer patients contained on average 2.2 mg/ml (range 0.8-3.9), with a higher average for large primary tumours. The major bound glycoproteins were α-2-macroglobulin, IgM and haptoglobin. Both the IgM and haptoglobin concentrations were similar in cancer compared to control sera, but the percentage bound to galectin-1 was lower for IgM and higher for haptoglobin: about 50% (range 20-80) in cancer sera and about 30% (range 25-50) in healthy sera. Galectin-1 binding and non-binding fractions were separated by affinity chromatography from pooled haptoglobin from healthy sera. The N-glycans of each fraction were analyzed by mass spectrometry, and the structural differences and galectin-1 mutants were used to identify possible galectin-1 binding sites. Galectin-1 binding and non-binding fractions were also analyzed regarding their haptoglobin function. Both were similar in forming complex with haemoglobin and mediate its uptake into alternatively activated macrophages. However, after uptake there was a dramatic difference in intracellular targeting, with the galectin-1 non-binding fraction going to a LAMP-2 positive compartment (lysosomes), while the galectin-1 binding fraction went to larger galectin-1 positive granules. In conclusion, galectin-1 detects a new type of functional biomarker for cancer: a specific type of glycoform of haptoglobin, and possibly other serum glycoproteins, with a different function after uptake into tissue cells.     

Differential susceptibility of transferrin glycoforms to chymotrypsin: a proteomics approach to the detection of carbohydrate-deficient transferrin

Transferrin exhibits heterogeneity in glycosylation characteristic of pathological changes in alcohol abuse and congenital disorders in glycosylation. This study investigated an alternative approach in the detection of carbohydrate-deficient transferrin based on the premise that glycosylation may afford some degree of protection to proteolytic action. Differential susceptibility to proteolysis by chymotrypsin was demonstrated for normal glycosylated and nonglycosylated recombinant human transferrin, using reverse-phase (RP) HPLC, matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, and LC-tandem mass spectrometry (MS/MS). Peptide fragmentation profiles were consistent with a predominantly high-specificity cleavage pattern of chymotrypsin. The observed peptide fragmentation profile showed that the C-lobe of recombinant full-length nonglycosylated transferrin (rhTf-NG) appeared to be preferentially cleaved, while cleavage of the N-lobe was restricted to the N-terminal and link sequence regions. Although chymotryptic cleavage sites abound in the N-lobe, their resistance to cleavage was independent of glycosylation. Compared to previous studies of lactoferrin, our data suggest disparity in the role by which glycosylation exerts a protective effect in the siderophilin family. It was clear from the transferrin digestions analyzed by HPLC that N-linked glycosylation did confer protection from proteolysis by chymotrypsin. After fragmentation, a range of peptides representing previously cryptic epitopes were identified as potential candidates for an immunological approach to differentiate between the different transferrin glycoforms. Based on its proximity to the Asn413 glycosylation site, a 15-mer peptide, m/z 1690.472 (NKSDNCEDTPEAGYF), was identified as a suitable candidate for raising anti-peptide antibodies for subsequent immunological detection. This novel approach could form the basis for an alternative assay or reference method for the detection of carbohydrate-deficient transferrin.     

Tim-3 expression and its role in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common tumors in the world, and its mortality is still on the rise. Limited treatments and low chemotherapy sensitivity of HCC make new therapeutic strategies urgently needed. With the rise of immune checkpoint blockade, anti-CTLA-4 antibodies and anti-PD-1 antibodies have shown therapeutic effects in various tumors. T cell immunoglobulin mucin-3 (Tim-3), a newly discovered immune checkpoint molecule, plays a major role in the development of HCC. Tim-3 can be used to evaluate the prognosis and therapeutic effects in HCC, and Tim-3 intervention has shown anti-tumor effects in preclinical experiments. This review summarizes findings regarding Tim-3 and HCC in recent years and discusses the rationale of Tim-3 as a therapeutic target for HCC.     

原发性肝癌的表观遗传学及其治疗

肝癌是一种严重危害人类健康的恶性疾病,在全世界患癌人群中,肝癌的发生率排第五,死亡率排第二。原发性肝癌(Hepatocellular carcinoma, HCC)是最普遍的肝癌组织学亚型,属于异质性疾病,对其治疗涉及遗传学、基因组学、环境毒理学等多个领域。尽管许多分子靶向治疗药物如索拉菲尼等已经进入临床应用并证明有效,但细胞毒性等负效应不容忽视,目前迫切需要新的治疗靶点和药物高效并选择性的杀伤肝癌细胞。大量证据表明,肝脏肿瘤的发生和发展与表观遗传学密切相关,DNA甲基化、组蛋白修饰、miRNA表达的异常及表观遗传相关基因表达的异常都是HCC中显著的表观遗传异常现象。表观治疗药物可能会逆转异常基因的表达,从而使HCC的发生和发展得以控制。文章综述了HCC表观遗传学治疗方面的研究进展,展望了未来利用类似的疗法治疗肝癌的潜力。     

Heat-shock protein 27: a potential biomarker for hepatocellular carcinoma identified by serum proteome analysis

Hepatocellular carcinoma (HCC) is the third leading cause of cancer mortality worldwide and ranks second in China. The prognosis of HCC remains dismal mainly because of its late diagnosis, especially in patients with coexisting chronic liver diseases. To identify serum biomarkers for HCC, sera from 20 healthy volunteers, 20 hepatitis B virus (HBV) infected patients and 20 HCC patients were selected for screening study and same number of sera into the same three groups were used for validation study. A strategy including sonication, albumin and immunoglobulin G (IgG) depletion and desalting was optimized for screening differentially expressed proteins of low abundance in serum. By 2-DE image analysis and MALDI-TOF-MS/MS identification, eight proteins including heat-shock protein 27 (HSP27), alpha-fetoprotein (AFP), alpha-1 antitrypsin, clusterin, caeruloplasmin, haptoglobin alpha2 chain, tranferrin and transthyretin were found significantly changed among the healthy, HBV and HCC groups. Further validation study by Western blot showed the detection of HSP27 in 90% HCC sera and two HBV sera, but in none of normal sera. Thus, 2-DE based serum proteome analysis can be useful in the screening of serum biomarkers for HCC and HSP27 could aid in the diagnosis of HCC though further validation is needed.     

The O-GlcNAcylation and its promotion to hepatocellular carcinoma

O-GlcNAcylation is a posttranslational modification that attaches O-linked β-N-acetylglucosamine (O-GlcNAc) to the serine and threonine residues of proteins. Such a glycosylation would alter the activities, stabilities, and interactions of target proteins that are functional in a wide range of biological processes and diseases. Accumulating evidence indicates that O-GlcNAcylation is tightly associated with hepatocellular carcinoma (HCC) in its onset, growth, invasion and metastasis, drug resistance, and stemness. Here we summarize the discoveries of the role of O-GlcNAcylation in HCC and its function mechanism, aiming to deepen our understanding of HCC pathology, generate more biomarkers for its diagnosis and prognosis, and offer novel molecular targets for its treatment.