EZH2 Protein Expression Associates with the Early Pathogenesis, Tumor Progression, and Prognosis of Non–Small Cell Lung Carcinoma

Purpose: Enhancer of zeste homolog 2 (EZH2) promotes carcinogenesis by epigenetically silencing tumor suppressor genes. We studied EZH2 expression by immunohistochemistry in a large series of non–small cell lung carcinomas (NSCLC) in association with tumor characteristics and patient outcomes. Experimental Design: EZH2 immunohistochemistry expression was analyzed in 265 normal and premalignant bronchial epithelia, 541 primary NSCLCs [221 squamous cell carcinomas (SCC) and 320 adenocarcinomas] and 36 NSCLCs with paired brain metastases. An independent set of 91 adenocarcinomas was also examined. EZH2 expression was statistically correlated with clinico-pathological information, and EGFR / KRAS mutation status. Results: EZH2 expression was significantly ( P P = 0.0013). EZH2 expression was significantly ( P P = 0.02 to P P = 0.025; HR = 1.54) and overall survival (OS; P = 0.0002; HR = 1.96). Furthermore, lung adenocarcinomas with low EZH2 levels and high expression of the lineage-specific transcription factor, TTF-1, exhibited significantly improved RFS ( P = 0.009; HR = 0.51) and OS ( P = 0.0011; HR = 0.45), which was confirmed in the independent set of 91 adenocarcinomas. Conclusion: In lung, EZH2 expression is involved in early pathogenesis of SCC and correlates with a more aggressive tumor behavior of adenocarcinoma. When EZH2 and TTF-1 expressions are considered together, they serve as a prognostic marker in patients with surgically resected lung adenocarcinomas. Clin Cancer Res; 19(23); 6556–65. ©2013 AACR .