Identification of proteins associated with lymph node metastasis of gastric cancer

Abstract

Purpose: The aim of this study was to identify proteins associated with gastric cancer lymph node metastasis and explore the clinicopathological significance of these proteins.

Methods: Gastric cancer tissues were obtained from 24 patients with high or low lymph node metastatic potential. Total cellular proteins were separated by two-dimensional gel electrophoresis (2-DE), analyzed by MALDI/TOF-TOF MS, and identified by a database search. Expression of 14-3-3β and profilin-1 was then immunohistochemically verified in paraffin-embedded gastric cancer tissues from 128 patients and analyzed by multivariate logistic regression models, Kaplan-Meier curves, and Cox proportional hazard models.

Results: A total of 26 differentially expressed proteins were identified, 20 of which were overexpressed and 6 of which were underexpressed. 14-3-3β and profilin-1 were upregulated in gastric cancer tissues with and without lymph node metastasis, respectively. Expression of 14-3-3β protein was associated, but profilin-1 expression was inversely associated with gastric cancer lymph node metastasis. Multivariate analysis showed that overexpression of 14-3-3β and reduced expression of profilin-1 were independent risk factors for gastric cancer lymph node metastasis, while 14-3-3β overexpression was an independent prognostic factor for gastric cancer patients.

Conclusions: The current study identified 26 differentially expressed proteins. Further studies showed that both 14-3-3β and profilin-1 protein may be useful biomarkers for prediction of gastric cancer lymph node metastasis and that expression of 14-3-3β was a prognostic marker for gastric cancer patients.

Fig. 1

The MALDI–TOF/TOF mass spectra for the identification of 14-3-3β and profilin-1 proteins. a The 2-DE images of spot 1 (14-3-3β protein). b The PMF mass spectrum generated from the digested peptides of spot 1, the MS/MS spectrum derived from the parent ion 1205.6213, in which the amino acid sequence DSTLIMQLLR was deduced. c The 2-DE images of spot 21 (profilin-1). d The PMF mass spectrum generated from the digested peptides of 2-DE spot 21, the MS/MS spectrum derived from the parent ion 1625.6292, in which the amino acid sequence DSLLQDGEFSMDLR was deduced

Fig. 2

Immunohistochemical staining of 14-3-3β protein in gastric cancer tissues. a Gastric cancer tissues (H&E, ×400 magnification); b negative expression of 14-3-3β in gastric cancer tissues (×400 magnification); c, d low expression of 14-3-3β in gastric cancer tissues (×100 and ×400 magnification, respectively); e, f high expression of 14-3-3β in gastric cancer tissues (×100 and ×400 magnification, respectively)

Fig. 3

Immunohistochemical staining of profilin-1 protein in gastric cancer tissues. a Gastric cancer tissues (H&E, ×400 magnification); b negative expression of profilin-1 in gastric cancer tissues (×400 magnification); c, d low expression of profilin-1 in gastric cancer tissues (×100 and ×400 magnification, respectively); e, f high expression of profilin-1 in gastric cancer tissues (×100 and ×400 magnification, respectively)

Fig. 4

Overall survival of gastric cancer patients stratified by 14-3-3β and profilin-1 expression. a Kaplan–Meier curves for overall survival of patients according to 14-3-3β expression. b Kaplan–Meier curves for overall survival of gastric cancer patients according to profilin-1 expression