P-cadherin promotes liver metastasis and is associated with poor prognosis in colon cancer

P-cadherin belongs to the family of classic cadherins, which is important for maintaining cellular localization and tissue integrity. Recently, it has become evident that P-cadherin contributes to the oncogenesis of many tumor types, including melanoma, prostate, breast, and colon carcinomas. Although cadherin switching is a crucial step in metastasis, the role of P-cadherin in colon cancer metastasis to the liver is unknown. In this study, we performed gene expression analysis and found that the level of P-cadherin was higher in tissue from liver metastases of colon cancer than in the corresponding primary colon cancer tissues. IHC analysis also showed that P-cadherin expression was significantly higher in liver metastases than in paired primary colorectal cancer tumors. Knockdown of P-cadherin in colon cancer cells inhibited wound healing, proliferation, and colony formation and resulted in developing fewer liver metastatic foci and reducing the tumor burden in vivo. Inhibition of P-cadherin expression also induced the up-regulation of E-cadherin and the down-regulation of β-catenin and its downstream target molecules, including survivin and c-Myc. In summary, these results uncover a novel function of P-cadherin in the regulation of colon cancer metastasis to the liver, suggesting that blocking the activity of P-cadherin or its associated signaling may be a valuable target for the treatment of hepatic metastases of colon carcinomas.