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. 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. 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 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.