The association of the expression level of protein tyrosine phosphatase PRL-3 protein with liver metastasis and prognosis of patients with colorectal cancer

Purpose. To investigate PRL-3 protein expression in normal colorectal epithelia and colorectal cancers with monoclonal antibody (MAb) against PRL-3. Methods. MAb against PRL-3 was prepared with the hybridoma technique, and its specificity was confirmed with ELISA and Western blotting assays. The expression of PRL-3 protein in normal colorectal epithelia and colorectal cancers was examined by immunohistochemistry assay. Logistic regression and survival analysis were performed to determine the clinical significance of PRL-3 expression. Results. MAb 3B6 against PRL-3 was obtained and showed high specificity. PRL-3 protein was expressed in two of 28 (7.1%) normal colorectal epithelia, 21 of 88 (23.9%) primary colorectal cancers, 22 of 41 (53.7%) metastatic lymph nodes and eight of 12 (66.7%) liver metastases, respectively. The PRL-3 expression rates of metastases were significantly higher than those of primary colorectal cancers and normal colorectal epithelia (P <0.05). PRL-3 expression was significantly associated with the liver metastasis of colorectal cancer (P = 0.004) and tended to shorten survival time (P = 0.0145). Conclusions. This is the first study demonstrating that PRL-3 is a potential marker for liver metastasis of colorectal cancer and negatively influences the prognosis of colorectal cancer patients.