OBJECTIVETo explore the potential markers of colorectal cancer metastasis and the influence of 5-FU on differentially expressed proteins by using proteomic technology, and to elucidate the mechanism of colorectal cancer metastasis.

METHODSHuman colorectal carcinoma cell lines of different metastatic potential, Lovo and SW480 were conventionally cultured, and the protein was extracted. 50% inhibitory concentration (IC(50)) of 5-FU to these two cell lines was measured by MTT assay. Proteins of these two cell lines after intervention by 5-FU at IC(50) were extracted, then 2-dimensional gel electrophoresis was conducted for the proteins. The differential protein spots were examined by mass spectrometry and analyzed by bioinformatics. Difference of expressed proteins in two cell lines before and after the intervention of 5-FU was validated by Western blot and immunofluorescence.

RESULTSEleven differentially expressed proteins were identified by 2-dimensional gel electrophoresis and mass spectrometry. The hnRNP K protein and PDI were selected to be examined by Western blot and immunofluorescence. Results revealed that the expression of hnRNP K in Lovo was higher than that in SW480, while the expression of PDI was lower in Lovo. After intervention by 5-FU at IC(50), the expression of hnRNP K in Lovo decreased more as compared to SW480, while the expression of PDI in SW480 increased more as compared to Lovo.

CONCLUSIONThere are significant differences in expression of hnRNP K and PDI proteins between Lovo and SW480 cell lines, and the proteins alter regularly after 5-FU intervention.