Genome‐wide chromatin analysis of ffpe tissues using a dual‐arm robot with clinical potential

Although chromatin immunoprecipitation and next‐generation sequencing (ChIP‐seq) using formalin‐fixed paraffin‐embedded tissue (FFPE) has been reported, it remained elusive whether they retained accurate transcription factor binding. Here, we developed a method to identify the binding sites of the insulator transcription factor CTCF and the genome‐wide distribution of histone modifications involved in transcriptional activation. Importantly, we provide evidence that the ChIP‐seq datasets obtained from FFPE samples are similar to or even better than the data for corre-sponding fresh‐frozen samples, indicating that FFPE samples are compatible with ChIP‐seq analy-sis. H3K27ac ChIP‐seq analyses of 69 FFPE samples using a dual‐arm robot revealed that driver mutations in EGFR were distinguishable from pan‐negative cases and were relatively homogeneous as a group in lung adenocarcinomas. Thus, our results demonstrate that FFPE samples are an important source for epigenomic research, enabling the study of histone modifications, nuclear chromatin structure, and clinical data.