Identification of transgelin as a potential novel biomarker for gastric adenocarcinoma based on proteomics technology

Purpose To find a biomarker for gastric adenocarcinomas (GA). Methods Ten protein expression profiles of GA and paired non-neoplastic mucosa tissues were analyzed by two-dimensional gel electrophoresis. Forty-two protein spots that were differentially expressed by twofold or greater between cancer and normal mucosa tissue were excised and identified by MALDI-TOF/TOF MS. One of the over-expressed proteins identified in GA was transgelin, which was chosen for further verification by immunohistochemistry and western blotting. Results Forty-two distinct proteins that were differentially expressed at least twofold between the tissues were identified. Expression of 29 of these proteins was decreased (ratio >= 2, P < 0.01), including adenosine deaminase; and 13 proteins displayed over-expression in cancer tissue (ratio >= 2, P < 0.01), including transgelin. The results of immunohistochemistry confirmed that transgelin was indeed over-expressed in 22 cases of GA (22/41, 53.66%), with strong cytoplasmic staining in cancer cells of positive samples, this was absent in most paired non-neoplastic mucosa cells or gastric ulcer tissues (n = 20). Transgelin was found over-expressed in 21 samples of cancer tissue (21/41, 51.22%) when detected by western blot. Conclusion This work demonstrates that differentially expressed proteins can be identified by proteomics technology combined with immunohistochemistry and western blot analyses. We have identified one such protein, transgelin, as a novel biomarker for GA.