Clinical and prognostic significance of Yes-associated protein in colorectal cancer.

The Hippo signaling pathway is a critical regulator of organ size control during development, and its deregulation is associated with cancers. Acting downstream of this pathway, Yes-associated protein (YAP) was implicated in tumorigenesis. The present study aimed to explore the expression patterns and clinical significance of YAP in human colorectal cancer (CRC). In addition, we investigated the relationship between YAP expression and Wnt/β-catenin pathway activation in CRC. A total of 139 cases of CRC tissues were investigated by immunohistochemistry for the expression of YAP, cyclin D1, and β-catenin. The association between YAP expression and clinicopathologic features was analyzed. Our results showed that YAP was overexpressed in 52.5 % (73/139) cases of CRC and predominantly presented in the nucleus. There was an excellent correlation between YAP expression and pTNM stage (p = 0.0024). YAP expression in CRC was significantly correlated with nodal status (p = 0.0034), tumor status (p = 0.0382), and cyclin D1 overexpression (p < 0.0001). Importantly, YAP expression was associated with short overall survival (p < 0.001). Furthermore, patients with YAP-positive and nuclear β-catenin-positive profiles had worse overall survival. Univariate and multivariate analyses revealed that YAP expression was an independent prognostic indicator of CRC (p = 0.0207). Our results indicated that YAP overexpression contributed to the tumorigenesis and played a pivotal role in the progression in CRC, and the interaction of YAP and Wnt/β-catenin pathways needs further exploration.