Differential gel-based proteomic approach for cancer biomarker discovery using human plasma

Plasma protein biomarkers of hepatocellular carcinoma in HCV-infected alcoholic patients with cirrhosis

Hepatocellular carcinoma (HCC) is one of the most common and lethal cancers in the world, with limited options for treatment unless timely diagnosed. Chronic hepatitis C virus (HCV) infection and persistent heavy alcohol consumption are independent risk factors for HCC development, which may induce a specific protein expression pattern different from those caused separately. The aim of the study was to identify protein biomarkers for the detection of HCC in HCV-infected alcoholic patients with cirrhosis in order to improve survival. We compared protein expression profiles of plasma samples from 52 HCV-infected alcoholic patients with and without HCC, using 2-D DIGE coupled with MALDI-TOF/TOF mass spectrometry. The 2-D DIGE results were analyzed statistically using Decyder software, and verified by western-blot and ELISA. In plasma samples from HCV-infected alcoholic patients, we found significantly differential expression profiles of carboxypeptidase-N, ceruloplasmin (CP), complement component 4a (C4a), fibrinogen-alpha (FGA), immunoglobulin mu chain C region, serum albumin, and serum paraoxonase/arylesterase 1 (PON1). Deregulation of plasma/serum levels of the identified proteins was associated to HCV, ethanol consumption, and/or HCC progression. In the validation through ELISA, C4a serum concentration was increased in HCC patients (2.4±1 ng/mg vs 1.8±0.6 ng/mg; p = 0.029), being the only independent predictor of HCC in the multivariate analysis (OR = 2.15; p = 0.015), with an AUROC = 0.70. The combination of C4a, FGA, CP and PON1 improved slightly the predictive ability of C4a alone (AUROC 0.81). In conclusion, we identified proteins related to acute-phase response, oxidative stress, or immune response, whose differential expression in plasma may be attributed to the presence of HCC. Among them, C4a, and its combination with CP, FGA and PON1, could be considered as potentially reliable biomarkers for the detection of HCC in HCV-infected alcoholic patients.

Identification of candidate biomarkers for hepatocellular carcinoma in plasma of HCV-infected cirrhotic patients by 2-D DIGE

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.