Aim: To develop lymph node metastasis (LNM)-associated biomarkers for colorectal cancer (CRC) using quantitative proteome analysis.
Methods: Differences in protein expression between primary CRC with LNM (LNM CRC) and without LNM (non-LNM CRC) were assessed using methyl esterification stable isotope labeling coupled with 2D liquid chromatography followed by tandem mass spectrometry (2D-LC-MS/MS). The relationship to clinicopathological parameters and prognosis of candidate biomarkers was examined using an independent sample set.
Results: Forty-three proteins were found to be differentially expressed by at least 2.5-fold in two types of CRC. S100A4 was significantly upregulated in LNM CRC compared with non-LNM CRC, which was confirmed by Western blotting, immunohistochemistry and real-time quantitative polymerase chain reaction. Further immunohistochemistry on another 112 CRC cases showed that overexpression of S100A4 frequently existed in LNM CRC compared with non-LNM CRC (P<0.001). Overexpression of S100A4 was significantly associated with LNM (P<0.001), advanced TNM stage (P<0.001), increased 5-year recurrence rate (P<0.001) and decreased 5-year overall survival rate (P<0.001). Univariate and multivariate analyses indicated that S100A4 expression was an independent prognostic factor for recurrence and survival of CRC patients (P<0.05).
Conclusion: S100A4 might serve as a powerful biomarker for LNM and a prognostic factor in CRC.
Keywords: Colorectal cancer; Lymph node metastasis; Prognosis; Proteome analysis; S100A4.