Abstract 5108: Quantitative proteomic analysis of cell-surface membrane proteins: Biomarker discovery in endometrial cancer
Authors: Yokoyama Takuhei , Enomoto Takayuki , Serada Satoshi , Matsuzaki Shinya , Kimura Toshihiro , Ueda Yutaka , Fujita Masami , Yoshino Kiyoshi , Kim Ayako , Fujimoto Minoru , Kimura Tadashi , Naka Tetsuji 
Published: June 2012

Abstract
Background. Endometrial cancer is one of the most common malignancies of the female genital tract. The identification of proteins for prognostic assessment and therapeutic targets in this disease is of significant clinical importance. Quantitative proteomic analysis provides a powerful approach in screening for alterations in protein levels and post-translational modifications that are associated with tumors. To date, proteomic studies of cancer have focused particularly on sub-cellular compartments or post-translational modifications. An analysis of the differential expression of cell-surface membrane proteins would be of particular interest, since these proteins play key roles in cell function including cell migration and drug resistance.
Purpose of study. To identify membrane proteins overexpressed in endometrial cancer which may represent novel biomarkers of disease and therapeutic targets.
Procedures. We developed a biotinylation-based approach for cell membrane enrichment combined with iTRAQ (isobaric tags for relative and absolute quantitation) technology using nano-LC-MS/MS analysis, to identify cell surface proteins overexpressed in seven endometrial cancer cell lines compared with a control normal endometrial cell line.
Results. 365 proteins were identified, of which, 65 proteins (18%) possessed a trans-membrane domain. We identified overexpression of 24 membrane proteins in endometrial cancer cell lines compared with a normal endometrial cell line. By this proteomic approach, we identified several tumor antigens which included antigens previously associated with endometrial cancer and antigens not previously reported in this disease. Tumorigenic proteins such as neural cell adhesion molecule L1 (NCAML1), previously reported to be overexpressed in endometrial cancer, were identified. Interestingly we also identified Claudin-4, a protein associated with poor prognosis in various cancers, but not previously reported in the pathogenesis of cancer. In addition, we also successfully identified novel antigens associated with endometrial cancer.
Conclusions. We developed a high throughput cell-surface membrane proteomic analysis combining biotinylation of cell-surface membrane protein and iTRAQ technology. In addition to the identification of previously reported tumor antigens such as NCAML1 and Claudin-4, we also identified novel tumor antigens in endometrial cancer by this methodology. This iTRAQ based quantitative proteomic analysis represented a useful approach in screening for novel disease biomarkers and therapeutic targets. Further studies on the physiological role of novel tumor antigens overexpressed in endometrial cancer and their application as biomarkers/therapeutic targets are underway.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5108. doi:10.1158/1538-7445.AM2011-5108