Abstract
Abstract Purpose: Differentiating Crohn's colitis (CC) and ulcerative colitis (UC) can be challenging even in combination of clinical, endoscopic, radiologic and histopathology examination. Biomarker studies have thus far been unsuccessful for disease delineation. We aim to use unique tissue proteomic methods to evaluate colonic tissue layers for potential biomarkers to identify CC vs. UC. Methods: Fresh-frozen colon specimens from resections for IBD and/or colorectal cancer were retrospectively retrieved. Colitis diagnoses were histologically re-confirmed by a blinded gastrointestinal pathologist. Three sample groups (n=5 each group) were examined: normal colon from CRC specimens (control), UC & CC. MALDI-MS was used to profile mucosal and submucosal compartments individually. Frozen tissues were sectioned at ∼10–15 μm for mounting onto either metal or conductive glass target plates (the glass plates allowing for histologic and MALDI-MS analysis on the same section). Sinapinic acid (20 mg/mL in 50:50 acetonitrile: 0.1% TFA in water) was used to give the best combination of uniform crystal coverage and signal quality for direct tissue protein analysis. Results: MALDI-MS achieved high mass accuracy (±0.01 Daltons) in the lower mass range (<15 kDa). There was distinguishable isotopic resolution of mass-to-charge ratio (m/z) values between normal vs the IBD and more strikingly between CC vs. UC (p< 0.0009) of SAM and FDR tests. There were 5 statistically significant discriminative m/z peaks observed in CC vs UC submucosa. The mucosa did not yield such distinctive peaks. Both the mucosa and submucosa provided signatures that differentiated IBD (CC or UC)) from control tissues (p< 0.001). Conclusions: MALDI-MS tissue profiling as described distinguished the colitides. The methodology revealed 5 m/z peaks of interest. Analyses are underway to identify these IBD discriminative proteins. We hypothesize that these biomarker candidates that distinguish UC from CC will allow delineation of indeterminate colitis into UC or CC. Whether these protein fingerprints play a role in colonic carcinogenesis remains to be elucidated. 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 LB-463. doi:10.1158/1538-7445.AM2011-LB-463
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