Identification of proteins expressed differently among surgically resected stage I lung adenocarcinomas

Abstract

Rationale: Among patients with surgically resected stage I lung adenocarcinoma, some succumb to early recurrence, while others survive for more than 5 years. Few markers to predict prognoses in these patients have been accepted. Recent advances in proteomic methodologies offer a unique chance to identify new candidate biomarkers. The aim of this study is to find differences in protein expression in resected lung cancer tissue of stage I adenocarcinoma from patients with no recurrence for more than 5 years and from those with early recurrence. Methods: Lung cancer tissues were obtained from 15 patients with pathologically confirmed stage I adenocarcinoma. The patients were divided into two groups, those with recurrence within 36 months (early recurrence group, n = 9) and those that were disease-free for over 5 years (disease free group, n = 6). Tissue proteins were separated by a two-dimensional electrophoresis long gel system (30 x 40 cm) with set ranges (3-10NL) and examined by nano-LC-ESI-MS/MS. Western blot assays were performed to validate these proteins. Results: Twelve protein spots were up-regulated and 8 were down-regulated in the disease-free group as compared with the recurrence group. Of the 12 up-regulated proteins, haptoglubin, tau-tubulin kinase-2 (TTBK2), thymidine phosphorylase, annexin-1, PIN1, CAPG, and SEC23 were validated by Western blot Among the 8 down-regulated proteins, serpinB6 and trangelin-2 were validated. Conclusions: A total of 9 differentially expressed proteins were successfully extracted, identified, and confirmed from stage I lung adenocarcinoma tissues. The increased or decreased expression of these proteins according to prognosis may be the basis for further studies of proteomics in developing prognostic biomarkers. (c) 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.