Abstract 2094: Correaltions between genome-wide DNA methylation profiles and genomic driver aberrations during multistage lung adenocaricinogenesis
Authors: Hamada Kenichi , Tian Ying , Fujimoto Mao , Yoriko Takahashi , Kohno Takashi , Tsuta Koji , Watanabe Shun-ichi , Yoshida Teruhiko , Asamura Hisao , Kanai Yae , Arai Eri 
Published: July 2021

Abstract
The aim of this study was to clarify correlations between epigenomic and genomic alterations during multistage lung adenocarcinogenesis. Single-CpG resolution genome-wide DNA methylation analysis with the Infinium HumanMethylation27 BeadChip was performed using 162 paired samples of non-cancerous lung tissue (N) and corresponding tumorous tissue (T) from patients with lung adenocarcinomas. Correlations between DNA methylation data on the one hand and clinicopathological parameters and genomic driver mutations, i.e. mutations of EGFR, KRAS, BRAF, and HER2 and fusion involving ALK, RET, and ROS1, were examined. In N samples, which were considered to be at precancerous stages, DNA methylation levels in 12,629 probes were significantly correlated with recurrence-free survival. DNA methylation profiles at the precancerous N stages may determine the prognostic outcome. Principal component analysis revealed that distinct DNA methylation profiles at the precancerous N stage tended not to induce specific genomic driver mutations. Most of the genes showing significant DNA methylation alterations during transition from N to T were shared by two or more driver aberration groups, indicating that, in general, each driver mutation does not induce a specific DNA methylation profile. Commonly shared DNA methylation alterations which could potentially result in expression abnormalities were enriched among transcriptional factors. In contrast, only 67 genes showed EGFR mutation-specific or “pan-negative”-specific DNA methylation alterations. Among the 67 genes, most of the DNA methylation alterations were correlated with clinicopathological parameters reflecting tumor aggressiveness. We further focused on the ZNF132 gene, for which DNA hypermethylation had been observed only in the “pan-negative”-type lung adenocarcinomas and was significantly correlated with their vascular invasion. 5-aza-2'-deoxycytidine treatment restored the expression levels of ZNF132 mRNA in lung adenocarcinoma cell lines, indicating that ZNF132 had been silenced due to DNA hypermethylation. Knockdown of ZNF132 using siRNA transfection led to increased cell migration ability, rather than increased cell growth or reduced apoptosis. We concluded that DNA hypermethylation of the ZNF132 gene participates in the clinicopathological aggressiveness of “pan-negative”-type lung adenocarcinomas. In addition, DNA methylation alterations at the precancerous stage may determine tumor aggressiveness, and such alterations that accumulate after driver mutation may additionally modify clinicopathological features through alterations of gene expression.
Citation Format: Kenichi Hamada, Ying Tian, Mao Fujimoto, Takahashi Yoriko, Takashi Kohno, Koji Tsuta, Shun-ichi Watanabe, Teruhiko Yoshida, Hisao Asamura, Yae Kanai, Eri Arai. Correaltions between genome-wide DNA methylation profiles and genomic driver aberrations during multistage lung adenocaricinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2094.