Glycoproteomics using fluid-based specimens in the discovery of lung cancer protein biomarkers: Promise and challenge
Department of Pathology, the Johns Hopkins Medical Institutions, Baltimore, MD, 21287. PROTEOMICS - CLINICAL APPLICATIONS
(Impact Factor: 2.96).
10/2012; 7(1-2). DOI: 10.1002/prca.201200105
Lung cancer is the number one cancer in the US and worldwide. In spite of the rapid progression in personalized treatments, the overall survival rate of lung cancer patients is still suboptimal. Over the past decade, tremendous efforts have been focused on the discovery of protein biomarkers to facilitate the early detection and monitoring lung cancer progression during treatment. In addition to tumor tissues and cancer cell lines, a variety of biological material has been studied. Particularly in recent years, studies using fluid-based specimen or so-called "fluid-biopsy" specimen have progressed rapidly. Fluid specimens are relatively easier to collect than tumor tissue, and they can be repeatedly sampled during the disease progression. Glycoproteins have long been recognized to play fundamental roles in many physiological and pathological processes. In this review, we focus the discussion on recent advances of glycoproteomics, particularly in the identification of potential protein biomarkers using so-called fluid-based specimens in lung cancer. The purpose of this review is to summarize current strategies, achievements and perspectives in the field. This insight will highlight the discovery of tumor-associated glycoprotein biomarkers in lung cancer and their potential clinical applications.
Figures in this publication
Available from: Hui Zhang
- "In lung tissue, protein expression directly reflects the physiological and/or pathological status of the lung parenchyma
[9-12]. Several recent studies have discovered that many proteins are differentially expressed in lung cancers
[13-18]. The complex protein changes and/or signature of protein expression, particularly those associated with NSCLC, still need to be further defined. "
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ABSTRACT: Lung cancer is the number one cause of cancer-related deaths in the United States and worldwide. The complex protein changes and/or signature of protein expression in lung cancer, particularly in non-small cell lung cancer (NSCLC) has not been well defined. Although several studies have investigated the protein profile in lung cancers, the knowledge is far from complete. Among early studies, mucin5B (MUC5B) has been suggested to play an important role in the tumor progression. MUC5B is the major gel-forming mucin in the airway. In this study, we investigated the overall protein profile and MUC5B expression in lung adenocarcinomas, the most common type of NSCLCs.
Lung adenocarcinoma tissue in formalin-fixed paraffin-embedded (FFPE) blocks was collected and microdissected. Peptides from 8 tumors and 8 tumor-matched normal lung tissue were extracted and labeled with 8-channel iTRAQ reagents. The labeled peptides were identified and quantified by LC-MS/MS using an LTQ Orbitrap Velos mass spectrometer. MUC5B expression identified by iTRAQ labeling was further validated using immunohistochemistry (IHC) on tumor tissue microarray (TMA).
A total of 1288 peptides from 210 proteins were identified and quantified in tumor tissues. Twenty-two proteins showed a greater than 1.5-fold differences between tumor and tumor-matched normal lung tissues. Fifteen proteins, including MUC5B, showed significant changes in tumor tissues. The aberrant expression of MUC5B was further identified in 71.1% of lung adenocarcinomas in the TMA.Discussions: A subset of tumor-associated proteins was differentially expressed in lung adenocarcinomas. The differential expression of MUC5B in lung adenocarcinomas suggests its role as a potential biomarker in the detection of adenocarcinomas.
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ABSTRACT: Several recent studies have suggested that EGFR and KRAS mutations may be different in primary and metastatic tumors. It is also not well studied whether or not conventional chemotherapy has any effect on EGFR or KRAS mutations. In this study, we compared EGFR and KRAS mutations in primary and unrelated metastatic lung adenocarcinomas from retrospectively collected clinical cases. We also examined the potential effect of chemotherapy on EGFR and KRAS mutations in these 2 groups based on available clinical information. Using Johns Hopkins Hospital archives, 379 lung adenocarcinomas with EGFR and KRAS mutational analyses were included. Mutational status was determined by sequencing exons 18 to 21 of EGFR and codons 12 and 13 of KRAS. Clinical information was correlated. The overall mutational rates in primary and metastatic tumors were comparable. In 213 primary tumors, there was no significant difference of EGFR and KRAS mutational rates in the prechemotherapy and postchemotherapy groups (P > .05), whereas in 166 metastatic tumors, EGFR and KRAS mutations were 12.8% and 36.1% in the prechemotherapy group and 27.3% and 18.2% in the postchemotherapy group (P < .05). Although our study is an unpaired study, it suggests that mutational status in metastatic tumors may need to be tested, especially if the patient had chemotherapy before the test. Additional studies are needed to further investigate the mechanism and clinical significance of the findings.
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ABSTRACT: Cytological examination of cells from bronchoalveolar lavage (BAL) is commonly used for the diagnosis of lung cancer. Proteins released from lung cancer cells into BAL may serve as biomarkers for cancer detection. In this study, N-glycoproteins in 8 cases of BAL fluid, as well as 8 lung adenocarcinoma tissues and 8 tumor-matched normal lung tissues, were analyzed using the solid-phase extraction of N-glycoprotein (SPEG), iTRAQ labeling and liquid chromatography tandem mass spectrometry (LC-MS/MS). Of 80 glycoproteins found in BAL specimens, 32 were identified in both cancer BAL and cancer tissues with levels of 25 glycoproteins showing at least a 2-fold difference between cancer and benign BAL. Among them, 8 glycoproteins showed greater than 2-fold elevations in cancer BAL, including Neutrophil elastase (NE), Integrin alpha-M, Cullin-4B, Napsin A, Lysosome-associaed membrane protein 2 (LAMP2), Cathepsin D, BPI fold-containing family B member 2, and Neutrophil gelatinase-associated lipocalin. The levels of Napsin A in cancer BAL were further verified in an independently collected 39 BAL specimens using an ELISA assay. Our study demonstrates that potential protein biomarkers in BAL fluid can be detected and quantified.
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