Proteomic profiling of proteins associated with lymph node metastasis in colorectal cancer

Lymph node metastasis (LNM) is associated with poor prognosis in colorectal cancer (CRC). The presence or absence of lymph node metastases is a strong independent prognostic factor for CRC survival. Investigation of proteins associated with the process of lymph node metastasis (LNM) is crucial for understanding of the molecular mechanisms underlying the LNM process and for predicting the CRC prognosis. In the present study, proteins from CRC tissues and adjacent normal mucosa (NMC) were examined using two-dimensional gel electrophoresis coupled with MALDI-TOF-MS. The expression levels of Ferritin Heavy Chain (FHC) were decreased in LNM CRC as compared to those in non-LNM CRC, while the expression of Cathepsin D and Ubiquitin C-terminal hydrolase-L1 (UCH-L1) were increased in LNM CRC. The results were confirmed by Western blotting and immunohistochemical staining. Furthermore, in vitro cell invasion assay showed that the overexpression of UCH-L1 through gene transfection increased the invasive ability of HCT8 cells, suggesting that UCH-L1 is not only a biomarker for LNM in CRC, but also a functional protein that may play a significant role in cell migration. The proteins identified in the present study should further our understanding of the LNM process of CRC and may become useful markers for diagnosis and targets for therapeutic interventions.