2‐D difference gel electrophoresis of the lung squamous cell carcinoma versus normal sera demonstrates consistent alterations in the levels of ten specific proteins

Abstract

Research Article 2-D difference gel electrophoresis of the lung squamous cell carcinoma versus normal sera demonstrates consistent alterations in the levels of ten specific proteinsMost lung cancers are diagnosed too late for curative treatment to be possible, therefore early detection is crucial. Serum proteins are a rich source of biomarkers and have the potential to be used as diagnostic and prognostic indicators for lung cancer. In order to examine differences in serum levels of specific proteins associated with human lung squamous carcinoma, immunodepletion of albumin and five other high-abundant serum proteins followed by 2-D difference gel electrophoresis (DIGE) analysis and subsequent MS was used to generate a panel of proteins found to be differentially expressed between the cancer and normal samples. Proteins found to have increased abundance levels in squamous cell carcinoma sera compared to normal sera included apolipoprotein A-IV precursor, chain F; human complement component C3c, haptoglobin, serum amyloid A protein precursor and Ras-related protein Rab-7b. Proteins found to have lower abundance levels in squamous cell carcinoma sera compared to normal sera included alpha-2-HS glycoprotein, hemopexin precursor, proapolipoprotein, antithrombin III and SP40; 40. The data presented here demonstrate that high-abundant protein removal combined with 2-D DIGE is a powerful strategy for the discovery of potential biomarkers. The identification of lung cancer-specific biomarkers is crucial to early detection, which in turn could lead to a dramatic increase in survival rates. IntroductionOver 1 million people are diagnosed with lung cancer each year [1]. Most lung cancer is diagnosed too late for curative treatment to be possible. Efforts at early detection and treatment have had little success to date and hence the overall prognosis remains poor. In the majority of those diagnosed with lung cancer, the disease has already metastasised at the time of diagnosis. Lung cancer comprises broadly of two groups, small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC). NSCLC comprises more than 80% of lung cancers including squamous cell carcinoma, adenocarcinoma and large cell carcinoma, with squamous carcinoma being the most common type.A major factor in the high mortality of lung cancer patients is the presence of metastatic tumours in approximately two-thirds of patients at time of diagnosis [2]. Detection of cancer in these patients at earlier stages would increase survival rates dramatically. The identification of lung cancer-specific biomarkers is critical to early detection. The pathophysiology of lung squamous cell carcinoma development is complex and incompletely understood. Genetic alterations involved in the pathogenesis of lung cancer produce proteins involved in cell growth, invasion/ metastasis, differentiation, cell cycle processes, apoptosis and angiogenesis. Discovering these mechanisms and pathways will undoubtedly lead to new ways in dealing with prevention, early detection an...

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“…Samples were prepared as outlined previously [11]. Briefly, diluted samples (Buffer A) were centrifuged to remove lipids and particulates.…”

“…The protein pellets were resuspended in icecold DIGE lysis buffer (20 mM Tris, 7 M Urea, 2 M Thiourea, 4% CHAPS, pH 8.5). Protein quantification was performed using the Quick Start Bradford Protein Assay (Biorad) using BSA as a protein standard [11].…”

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