Depression of histone acetylation by alkylating antitumor agents in murine cells.

Treatment of Ehrlich ascites tumor cells with the alkylating agent triaziquone [2,3,5-tris(ethyleneimino)benzoquinone-1,4] and nitrogen mustard leads to a reduction of the posttranslational acetylation of histones. Acetylation of all core histones is affected. The reduction of labeling of acetylated sites is accompanied by a dose-dependent decrease in the extent of acetylation as indicated by the level of acetylation of H4. The depression of histone acetylation is expressed at all concentrations of the alkylating agents which cause significant inhibition of tumor cell proliferation. It could be excluded that the observed effects are caused by an impairment of acetyl coenzyme A synthesis.