Comparative analysis of histone H3 and H4 post-translational modifications of esophageal squamous cell carcinoma with different invasive capabilities.

Eukaryotic DNA is packaged into a chromatin with the help of four core histones (H2A, H2B, H3, and H4). Diverse histone post-translational modifications (PTMs) are hence involved in the regulation of gene transcription. However, how this regulation does work is still poorly understood and lacks details. Here we used the mass spectrometry-based proteomics approach to perform a comparative analysis of histone marks at a global level in two phenotypes of esophageal squamous cell carcinoma (ESCC) with different invasiveness. We obtained a comprehensive profiling of histone H3 and H4 PTMs including lysine methylation, acetylation and novel butyrylation. The correlation between histone marks and cancer invasive capabilities was further characterized and one distinguishable PTM, H4K79me2 was discovered and verified in this study. Immunohistochemistry analysis suggests that abnormal level of H4K79me2 may be related to poor survival of ESCC patients. Our results enrich the dataset of the feature pattern of global histone PTMs in ESCC cell lines. BIOLOGICAL SIGNIFICANCE: Core histone proteins, decorated by multiple biological significant protein post-translational modifications (PTMs) such as lysine acetylation and lysine methylation, are considered to regulate gene transcription and be associated with the development of cancer. Recent studies have further shown that global level of histone modifications is the potential hallmark of cancer to predict the clinical outcomes of human cancers. However, the regulation mechanism is largely unknown. Here we used the mass spectrometry based proteomics coupled with stable isotope labeling with amino acids in cell culture (SILAC) to characterize the global levels of histone marks in two phenotypes of esophageal squamous cell carcinoma (ESCC) cell lines with different invasive capabilities. To the best of our knowledge, it is the first report about the comparative analysis for histone marks of the different invasive ESCC cell lines. A significantly differential level of histone modification, H4K79me2, was determined and verified. Immunohistochemistry analysis further suggests that abnormal level of H4K79me2 may be related to poor survival of ESCC patients. Our results could contribute to understanding the different expressions of global histone PTMs in different invasive ESCC cell lines.