Usefulness of acute phase proteins for monitoring development of hepatocellular carcinoma in hepatitis B virus carriers

Identification of circulating protein biomarkers in patients with hepatocellular carcinoma concomitantly infected with chronic hepatitis C virus

CONTEXT

The incidence rate of hepatocellular carcinoma (HCC) is higher in developing countries, and most cases are associated with chronic hepatitis C virus (HCV) infection.

OBJECTIVE

To evaluate the circulating proteins as liver biomarkers for the identification of HCC associated with HCV infection in Egyptian patients using LC-MS/MS analysis.

METHODS

Blood sera were collected from 31 HCC patients and the fractionated proteins were subjected to LC-MS/MS analysis. Protein candidates were validated by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Thirty-three proteins were significantly identified in the sera of HCC patients with persistent HCV infection. These proteins are involved in several biological processes including acute phase response, complement activation, hemostasis process and lipid metabolism. The level of lectin galactoside-binding soluble 3 binding protein (LGALS3BP), Kininogen-1 (KNG1), serum amyloid A2 (SAA2) and paraoxonase 1 (PON1) and alpha-fetoprtoein (AFP) were elevated in serum.

CONCLUSION

In HCC patients with chronic HCV infection, we identified a group of differentially expressed circulating proteins involved in regulating different cellular mechanisms.

Identification of Candidate Serum Biomarkers for Schistosoma mansoni Infected Mice Using Multiple Proteomic Platforms

BACKGROUND

Schistosomiasis is an important helminth infection of humans. There are few reliable diagnostic biomarkers for early infection, for recurrent infection or to document successful treatment. In this study, we compared serum protein profiles in uninfected and infected mice to identify disease stage-specific biomarkers.

METHODS

Serum collected from CD1 mice infected with 50-200 Schistosoma mansoni cercariae were analyzed before infection and at 3, 6 and 12 weeks post-infection using three mass spectrometric (MS) platforms.

RESULTS

Using SELDI-TOF MS, 66 discriminating m/z peaks were detected between S. mansoni infected mice and healthy controls. Used in various combinations, these peaks could 1) reliably diagnose early-stage disease, 2) distinguish between acute and chronic infection and 3) diagnose S. mansoni infection regardless the parasite burden. The most important contributors to these diagnostic algorithms were peaks at 3.7, 13 and 46 kDa. Employing sample fractionation and differential gel electrophoresis, we analyzed gel slices either by MALDI-TOF MS or Velos Orbitrap MS. The former yielded eight differentially-expressed host proteins in the serum at different disease stages including transferrin and alpha 1- antitrypsin. The latter suggested the presence of a surprising number of parasite-origin proteins in the serum during both the acute (n = 200) and chronic (n = 105) stages. The Orbitrap platform also identified many differentially-expressed host-origin serum proteins during the acute and chronic stages (296 and 220 respectively). The presence of one of the schistosome proteins, glutathione S transferase (GST: 25 KDa), was confirmed by Western Blot. This study provides proof-of-principle for an approach that can yield a large number of novel candidate biomarkers for Schistosoma infection.

Differential patterns of liver proteins in experimental murine hepatosplenic schistosomiasis

Schistosoma mansoni eggs produced by adult worms in the mesenteric vasculature become trapped in the liver, where they induce granulomatous lesions and strong immune responses. Infected individuals suffer from intestinal schistosomiasis (INT) in 90% of cases, whereas the remaining 10% present with severe hepatosplenic schistosomiasis (HS). The CBA/J mouse model mimics human disease, with 20% of infected mice developing hypersplenomegaly syndrome (HSS) that resembles HS and 80% developing moderate splenomegaly syndrome (MSS) similar to INT. We studied differential patterns of protein expression in livers of 20-week-infected CBA/J mice with MSS or HSS to understand the molecular changes that underlie these two disease forms. Using differential in-gel electrophoresis to identify differentially expressed protein spots, we found 80 protein spots significantly changed with infection and 35 changes specific to severe disease. In particular, the abundances of prohibitin 2, transferrin isoforms, and major urinary protein isoforms were significantly altered in HSS mice. Furthermore, annexin 5, glutathione S-transferase pi class, and S. mansoni phosphoenolpyruvate carboxykinase expression levels changed significantly with schistosome infection. Additionally, levels of major urinary protein decreased and levels of transferrin increased significantly in the sera of HSS mice compared to levels in sera of MSS or control mice, and these differences correlated to the degree of splenomegaly. These findings indicate that the liver protein abundances differ between MSS and HSS mice and may be used for the development of diagnostic markers for the early detection of hepatosplenic schistosomiasis.

Plasma and urine biomarkers in acute viral hepatitis E

Background

Hepatitis E, caused by the hepatitis E virus (HEV), is endemic to developing countries where it manifests as waterborne outbreaks and sporadic cases. Though generally self-limited with a low mortality rate, some cases progress to fulminant hepatic failure (FHF) with high mortality. With no identified predictive or diagnostic markers, the events leading to disease exacerbation are not known. Our aim is to use proteomic tools to identify biomarkers of acute and fulminant hepatitis E.

Results

We analyzed proteins in the plasma and urine of hepatitis E patients and healthy controls by two-dimensional Differential Imaging Gel Electrophoresis (DIGE) and mass spectrometry, and identified over 30 proteins to be differentially expressed during acute hepatitis E. The levels of one plasma protein, transthyretin, and one urine protein, alpha-1-microglobulin (α1m), were then quantitated by enzyme immunoassay (EIA) in clinical samples from a larger group of patients and controls. The results showed decreased plasma transthyretin levels (p < 0.005) and increased urine α1m levels (p < 0.001) in acute hepatitis E patients, compared to healthy controls. Preliminary results also showed lower urine zinc alpha glycoprotein levels in fulminant hepatitis E compared to acute disease; this remains to be confirmed with more fulminant cases.

Conclusion

Our results demonstrate the utility of characterizing plasma and urine proteomes for signatures of the host response to HEV infection. We predict that plasma transthyretin and urine α1m could be reliable biomarkers of acute hepatitis E. Besides the utility of this approach to biomarker discovery, proteome-level changes in human biofluids would also guide towards a better understanding of host-virus interaction and disease.

Modulation of Iron-Regulatory Genes in Human Hepatocellular Carcinoma and Its Physiological Consequences

Hepatocellular carcinoma (HCC) commonly develops in patients with underlying chronic liver disease. Additionally, the tumorous lesions of HCC patients are consistently characterized by the lack of iron accumulation even when arising in iron-loaded liver. However, the molecular mechanism leading to this observed phenomenon is currently poorly understood. In this study, all tumorous tissues from 24 HCC patients with chronic HBV infection were stained negative for iron when histologically assessed by Perls’ Prussian blue stain, whereas excess iron deposits were present in 17 of the 24 adjacent non-tumorous liver tissues. To elucidate the concerted regulation of iron homeostasis in these patients, we studied the gene expression profiling of 42 relevant iron-regulatory genes in the tumorous and adjacent non-tumorous liver tissues of these HCC patients along with 10 normal liver controls. Expression for most of the iron-regulatory genes, including hepcidin, transferrin receptor 2 (TfR2), transferrin (Tf), ceruloplasmin (Cp) and iron regulatory protein 1 (IRP1), were significantly down-regulated in the tumorous tissues of these patients compared to the adjacent non-tumorous liver tissues and normal liver controls. On the other hand, expression of hepcidin, TfR2, ferroportin 1 and DMT1 were significantly up-regulated in iron-loaded non-cirrhotic non-tumorous liver tissues as compared with normal liver controls. Hence, the reduction of hepcidin expression within the iron-depleted tumorous lesions likely reflects the physiological consequence of the obligate demand for iron in the rapidly growing neoplastic cells, whereas the up-regulation of hepcidin expression in the iron-loaded adjacent non-tumorous liver tissues is likely a physiological response.

O Labeling for a Quantitative Proteomic Analysis of Glycoproteins in Hepatocellular Carcinoma

INTRODUCTION: Quantitative proteomics using tandem mass spectrometry is an attractive approach for identification of potential cancer biomarkers. Fractionation of complex tissue samples into subproteomes prior to mass spectrometric analyses increases the likelihood of identifying cancer-specific proteins that might be present in low abundance. In this regard, glycosylated proteins are an interesting class of proteins that are already established as biomarkers for several cancers. MATERIALS AND METHODS: In this study, we carried out proteomic profiling of tumor and adjacent non-cancer liver tissues from hepatocellular carcinoma (HCC) patients. Glycoprotein enrichment from liver samples using lectin affinity chromatography and subsequent (18)O/(16)O labeling of peptides allowed us to obtain relative abundance levels of lectin-bound proteins. As a complementary approach, we also examined the relative expression of proteins in HCC without glycoprotein enrichment. Lectin affinity enrichment was found to be advantageous to quantitate several interesting proteins, which were not detected in the whole proteome screening approach. We identified and quantitated over 200 proteins from the lectin-based approach. Interesting among these were fetuin, cysteine-rich protein 1, serpin peptidase inhibitor, leucine-rich alpha-2-glycoprotein 1, melanoma cell adhesion molecule, and heparan sulfate proteoglycan-2. Using lectin affinity followed by PNGase F digestion coupled to (18)O labeling, we identified 34 glycosylation sites with consensus sequence N-X-T/S. Western blotting and immunohistochemical staining were carried out for several proteins to confirm mass spectrometry results. CONCLUSION: This study indicates that quantitative proteomic profiling of tumor tissue versus non-cancerous tissue is a promising approach for the identification of potential biomarkers for HCC.