Differences in the expression of epithelial-mesenchymal transition related molecules between primary tumors and pulmonary metastatic tumors in colorectal cancer

Purpose: Epithelial-mesenchymal transition (EMT) is a key event in cancer metastasis. This study immunohistochemically examined the expression of EMT-related molecules in both primary colorectal cancer and pulmonary metastases, and analyzed the expression pattern. Methods: Ten patients with colorectal cancer that underwent surgical resections for both the primary tumor and metastatic pulmonary tumors were included. The expression status of EMT-related molecules was examined using immunohistochemical staining. Results: Nine of the 10 cases maintained the expression of both E-cadherin and β-catenin in the primary site. The expression of E-cadherin and β-catenin in the pulmonary metastatic site was preserved in 10 and 12 out of 15 metastatic lesions, respectively. The EMT-related transcription factor, Twist, was positively expressed in all 10 cases, Smad interacting protein 1 (Sip1) in 9, Snail in 4 and Slug in 3 of the primary sites. On the other hand, staining for Twist, Sip1 and Snail at the metastatic pulmonary site, was negative in all 10 cases. Conclusion: The expression of EMT-related transcription factors in metastatic pulmonary tumors from colorectal cancer decreased in comparison to the primary tumors. These findings suggested that the expression status of EMT-related transcription factors might play an important role in the implantation of metastatic foci.