High Pin1 expression is associated with tumor progression in colorectal cancer

Background and Objectives: Peptidyl prolyl cis-trans isomerase (Pin1) isomerizes only phosphorylated serine or threonine residues preceding proline in certain proteins and affects the protein function. Pin1 interacts with many signaling pathways, including Writ signaling pathway that is crucial for colorectal tumorigenesis. Pin1 promotes cyclin D1 over-expression directly or through the stabilization of beta-catenin. Pin1 is over-expressed in some cancers such as prostate and breast cancers. This study aimed to determine whether Pin1 plays a role in colorectal tumorigenesis through the upregulation of beta-catenin and cyclin D1. Methods: Immunohistochemical analyses were performed on 105 colorectal cancer tissue samples using anti-Pin1, anti-beta-catenin, and anti-cyclin D1 antibodies. We examined the relationships between Pin1 expression and clinicopathological factors, prognosis, and beta-catenin/cyclin D1 expression. Results: High Pin1 expression was observed in 40 cases (38%) and positively correlated with histological type (P=0.0240), depth of invasion (P=0.0051), and staging (P = 0.0027) of colorectal tumors. High Pin l expression was also correlated with the over-expressions of both beta-catenin (P = 0.0225) and cyclin D1 (P = 0.0137). Conclusions: These results suggest that Pin1 plays an important role in colorectal tumorigenesis, presumably by increasing beta-catenin and cyclin D1 expressions.