Expression and prognostic value of epithelial-to-mesenchymal transition and cancer stem cellmarkersin primary lesions and liver metastases of colorectal cancers

Cancer stem cells (CSCs) and epithelial mesenchymal transition (EMT) markers are considered useful indicators associated with metastasis and prognosis of colorectal cancers (CRCs). However, only a few studies have focused on the expression of these useful markers in metastases. Metastasectomy is widely used in advanced CRCs, and thus the postoperative prognostic factors are worth investigating. The present study investigated the consistency and differences of target proteins between primary and metastatic lesions of colorectal cancer, and discussed the prognostic indicators following resection of colorectal liver metastases. Clinical data of 56 patients with liver metastases from colorectal cancer were collected and the expression levels of target proteins (Ki-67, CD133, CD44, Snail, E-cadherin and β-catenin) were detected in primary tumor and matched liver metastases via immunohistochemistry analysis. Paired comparison between both tissue types was performed. The prognostic values of the target proteins for resectable colorectal cancer liver metastases were assessed. No significant differences were observed between the primary tissues and metastatic tissues. The consistency rates of these protein expression levels ranged from 51.8–78.6%. The maximum diameter of the liver metastases was <5 cm. Low Snail expression in metastases was associated with a longer overall survival (OS) time following resection of colorectal liver metastases. Furthermore, N0 stage and low carcinoembryonic antigen levels were associated with a longer progression-free survival time. Notably, no significant differences were observed in expression levels of the target proteins between the primary tumors and liver metastases. Taken together, the results of the present study suggest that Snail expression in liver metastases may be used as a novel independent prognostic factor for OS following resection of colorectal liver metastases.