Loss of FAT Atypical Cadherin 4 Expression Is Associated with High Pathologic T Stage in Radically Resected Gastric Cancer.

Recent studies have revealed recurrent alterations in the cell adhesion gene FAT4, a candidate tumor suppressor gene, in cancer. FAT atypical cadherin 4 (FAT4) is a transmembrane receptor involved in the Hippo signaling pathway, which is involved in the control of organ size. Here, we investigated the loss of FAT4 expression and its association with clinicopathological risk factors in gastric cancer.,We assessed the expression of FAT4 by using immunohistochemistry on three tissue microarrays containing samples from 136 gastric cancer cases, radically resected in the Soonchunhyang University Cheonan Hospital between July 2006 and June 2008. Cytoplasmic immunoexpression of FAT4 was semi-quantitatively scored using the H-score system. An H-score of ≥10 was considered positive for FAT4 expression.,Variable cytoplasmic expressions of FAT4 were observed in gastric cancers, with 33 cases (24.3%) showing loss of expression (H-score <10). Loss of FAT4 expression was associated with an increased rate of perineural invasion (H-score <10 vs. ≥10, 36.4% vs. 16.5%, P=0.015), high pathologic T stage (P=0.015), high tumor-node-metastasis stage (P=0.017), and reduced disease-free survival time (H-score <10 vs. ≥10, mean survival 62.7±7.3 months vs. 79.1±3.1 months, P=0.025). However, no association was found between the loss of FAT4 expression and tumor size, gross type, histologic subtype, Lauren classification, lymphovascular invasion, or overall survival.,Loss of FAT4 expression appears to be associated with invasiveness in gastric cancer.