Global Histone Modifications Predict Prognosis of Resected Non–Small-Cell Lung Cancer

Abstract

Purpose: Epigenetic modifications may contribute to the development and progression of cancer. We investigated whether epigenetic changes involving multiple histones influence prognosis of non–small-cell lung cancer (NSCLC) patients. Patients and Methods: We used immunohistochemistry to assess histone 3 lysine 4 dimethylation (H3K4diMe), and acetylation of histone 2A lysine 5 (H2AK5Ac), histone 2B lysine 12, histone 3 lysine 9 (H3K9Ac), and histone 4 lysine 8 in resected tumor samples of 138 NSCLC patients. Data were analyzed using a recursive partitioning analysis (RPA). Results: The RPA classified the patients into seven distinct prognostic groups based on TNM stage (first node), histology, and histone modifications: H3K4diMe (< or ≥ 85% tumor cells), H3K9Ac (< or ≥ 68% tumor cells), and H2AK5Ac (< or ≥ 5% tumor cells). The seven groups were associated with significantly different disease-free (P < .0001) and overall survival (P < .0001). Interestingly, the four groups determined by stage I patients (below the first node) displayed dramatic differences in survival (median, 10 months in adenocarcinoma patients with H3K9Ac ≥ 68% v 147 months in nonadenocarcinoma patients with H3K4diMe ≥ 85%). A Cox model retained age and RPA groups as the sole independent factors significantly influencing overall survival. Conclusion: The prognostic influence of epigenetic changes involving multiple histones, in particular H2A and H3, is greater in early NSCLC, and evaluation of these changes may help in selecting early-stage NSCLC patients for adjuvant treatment. Our observations provide a rationale for the use of a combination of standard chemotherapy with drugs interacting with histone modifications, such as histone deacetylase inhibitors.