Abstract 3177: Early detection biomarker for colorectal malignancies identified by a novel comparative proteomic workflow
Authors: Florian T. Unger, Markus Meyer, Monika Spörl, Agnieszka Harasym, Katja Pursche, Hartmut Juhl, Kerstin A. David
Journal: Cancer Research (2011)

Abstract Colorectal cancer (CRC) ranks worldwide at third place for tumor diseases and account for an annual mortality rate of 492.000 cases. Despite the advances in treatment of CRC, patients mostly benefit from an early detection of malignancy. Although several molecular events are known to be associated with tumor development and progression the accuracy of currently practiced early detection of CRC has to be optimized. Therefore, the discovery of new and more reliable biomarker for diagnosis of early stages of cancer is still a challenge. Towards this end, our study was designed to identify protein biomarkers which are closely associated with the molecular events leading from epithelial adenoma to the early stages of carcinoma. Tissues from patients with epithelial adenoma (high dysplasia), carcinoma (stage I) and matched normal tissue (n = 10 for each group) were selected and analysed using our novel biomarker discovery platform. The workflow combines the cell specificity and the selectivity of laser capture microdissection (LCM) with the resolution power and sensitivity of liquid-chromatography (LC)-matrix-assisted-laser-desorption/ionization mass spectrometry (LC-MALDI-MS). According to this LCM-LC-MALDI-MS strategy microdissected cells were lysed and extracted proteins were digested with trypsin. Obtained peptides were separated by capillary reversed phase HPLC. Tryptic fragments were subsequently detected by reflector MALDI-MS measurements. Differential peptide analysis was performed to discover robust and significant expression differences between patient groups. Selected peptides were subsequently fragmented by MS/MS experiments to reveal protein identity. Up to 7000 ion signals ranging from m/z 800 to 4000 per sample were generated and used for statistical analysis. Our targeted biomarker discovery approach resulted in the identification of more than 30 biomarker candidates. The identified early detection biomarker candidates are involved in diverse cellular functions and can be linked to early or late events of tumor progression. Among these hNRPU, HSP90 and SFPQ were so far further analysed. All three biomarker candidates were significantly regulated between groups, showing increasing expression from normal across adenoma to carcinoma tissue. Currently these biomarkers are being validated using antibody based assays. In this study we were able to show that the newly established high resolution proteomic workflow is applicable for the detection and identification of regulated peptides in microdissected tissue compartments. In summary the established comparative proteomic workflow is suitable for the discovery of biomarker for miscellaneous applications (e.g. early detection, prognosis and prediction of response to therapy) 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 3177. doi:10.1158/1538-7445.AM2011-3177