The post-translational modification of the core
histones is critical to the regulation of
chromatin structure. Traditional methods for the determination of
histone modification utilize immunoassay techniques to determine the extent and site of post-translational modification. These methods, though sensitive, require site-specific
antibodies. This manuscript describes the application of reverse-phase high-pressure liquid chromatography and mass spectrometry (LC-MS) to analyze global modification levels of core
histones. The method is fast, sensitive, and easily automated. Furthermore, the technique gives the global patterns of modification for all four core
histones in a single experiment. The LC-MS method was optimized using
histones extracted from bovine thymus. These methods were then applied to the characterization of changes in
histone modification in
acute myeloid leukemia (AML) cell lines treated with
histone deacetylase (
HDAC) inhibitors. Dose-dependent changes in the distribution of modified core
histones were observed. These results were validated in primary
leukemia cells from patients with refractory or relapsed AML or
chronic lymphocytic leukemia (CLL) treated on a Phase I clinical trial of the
HDAC inhibitor depsipeptide. An increase in the relative abundance of specific acetylated forms of
histone H4 was readily observable in these patients at intervals of 4 and 24 h
after treatment.