• Sebahat Ocak, David B Friedman, Heidi Chen, Jamie A Ausborn, Mohamed Hassanein, Bruno Detry, Birgit Weynand, Frank Aboubakar, Charles Pilette, Yves Sibille, and Pierre P Massion.
• *Pôle Pneumologie, ORL et Dermatologie, PNEU, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain (UCL), Brussels, Belgium; †Division of Pneumology, Department of Internal Medicine, CHU Mont-Godinne, UCL, Yvoir, Belgium; ‡Department of Biochemistry, Vanderbilt University, Nashville, Tennessee; §Department of Biostatistics, Cancer Biostatistics Center, Vanderbilt University, Nashville, Tennessee; ‖Department of Cancer Biology, Vanderbilt University, Nashville, Tennessee; ¶Division of Allergy, Pulmonary, and Critical Care Medicine, Department of Medicine, Vanderbilt University, Nashville, Tennessee; #Department of Pathology, CHU Mont-Godinne, UCL, Yvoir, Belgium; ***Division of Pneumology, Department of Internal Medicine, Cliniques Universitaires St-Luc, UCL, Brussels, Belgium; ††Thoracic Program, Vanderbilt-Ingram Comprehensive Cancer Center, Nashville, Tennessee; and ‡‡Section of Pulmonary and Critical Care Medicine, Veterans Affairs Medical Center, Nashville, Tennessee.
• J Thorac Oncol. 2014 Mar 1; 9 (3): 324-36.

IntroductionSmall-cell lung cancer (SCLC) is the most aggressive subtype of lung cancer, with no early detection strategy or targeted therapy currently available. We hypothesized that difference gel electrophoresis (DIGE) may identify membrane-associated proteins (MAPs) specific to SCLC, advance our understanding of SCLC biology, and discover new biomarkers of SCLC.MethodsMAP lysates were prepared from three SCLCs, three non-small-cell lung cancers, and three immortalized normal bronchial epithelial cell lines and coanalyzed by DIGE. Subsequent protein identification was performed by mass spectrometry. Proteins were submitted to Ingenuity Pathway Analysis. Candidate biomarkers were validated by Western blotting (WB) and immunohistochemistry (IHC).ResultsPrincipal component analysis on the global DIGE data set demonstrated that the four replicates derived from each of the nine cell lines clustered closely, as did samples within the same histological group. One hundred thirty-seven proteins were differentially expressed in SCLC compared with non-small-cell lung cancer and immortalized normal bronchial epithelial cells. These proteins were overrepresented in cellular/tissue morphology networks. Dihydropyrimidinase-related protein 2, guanine nucleotide-binding protein alpha-q, laminin receptor 1, pontin, and stathmin 1 were selected as candidate biomarkers among MAPs overexpressed in SCLC. Overexpression of all candidates but RSSA in SCLC was verified by WB and/or IHC on tissue microarrays. These proteins were significantly associated with SCLC histology and survival in univariables analyses.ConclusionDIGE analysis of a membrane-associated subproteome discovered overexpression of dihydropyrimidinase-related protein 2, guanine nucleotide-binding protein alpha-q, RUVB1, and stathmin 1 in SCLC. Results were verified by WB and/or IHC in primary tumors, suggesting that investigating their functional relevance in SCLC progression is warranted. Association with survival requires further validation in larger clinical data sets.

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