Immunohistochemical analysis of the expression of E‐cadherin and ZEB1 in non‐small cell lung cancer

We performed an immunohistochemical analysis of the expression of zinc‐finger E‐box binding homeobox 1 (ZEB1), a master regulator of epithelial‐mesenchymal transition (EMT), and determined its relationship with E‐cadherin in 157 non‐small cell lung carcinomas (93 adenocarcinomas, 36 squamous cell carcinomas, 18 large cell carcinomas, and 10 pleomorphic carcinomas). Although the expression of E‐cadherin was low in the subset of adenocarcinomas (10%) and squamous cell carcinomas (11%), ZEB1 expression was only observed in one case of squamous cell carcinoma and none of the adenocarcinomas. In contrast, the low expression of E‐cadherin (50% and 90%, respectively) and the positive expression of ZEB1 (11% and 50%, respectively) were more frequently observed in poorly differentiated carcinomas (large cell carcinomas and pleomorphic carcinomas). Overall, the expression of ZEB1 was inversely correlated with that of E‐cadherin. Furthermore, the distribution of ZEB1‐positive cancer cells was more restricted than in the area in which the expression of E‐cadherin was lost, and the former was detected within the latter. We concluded that the expression of ZEB1 was not necessarily associated with the low expression of E‐cadherin in lung adenocarcinomas and squamous cell carcinomas. The expression of ZEB1 correlated with an undifferentiated and/or sarcomatoid morphology that may occur in the late stage of EMT.