HDAC inhibition increases H3K4me3 at the promoters of the BTK-targeting miRs, induces their expression, and results in a reciprocal decrease in BTK protein in CLL. (A) Accumulation of the transcriptionally permissive marks H3K4me2 and H3K4me3 after HDAC inhibition at the miR-147b, miR-210, miR-425, miR-1253, miR-4269, miR-4667-3p, CNDN1a (positive control), and miR-622 promoters (negative control) in CLL samples with adverse cytogenetics. Data are representative of 3 individual CLL samples analyzed by ChIP-Seq. (B) Accumulation of the transcriptionally permissive mark H3K9Ac3 after HDAC inhibition at the miR-147b, miR-210, miR-425, miR-1253, miR-4269, miR-4667-3p promoters using primers specific or nonspecific to the promoters for these miRs. Data represent mean ± SEM of 4 CLL samples. (C) Induction of miR-147b, miR-210, miR-425, miR-1253, miR-4269, miR-4667-3p in 79 CLL samples after HDAC inhibition. Expression of the BTK-targeting miRs were normalized to the expression of snRNA48, which did not change after HDAC inhibition (P < .001, mixed effects model). (D) Effect of abexinostat for 24 or 36 hours on BTK mRNA. Data represent mean ± SEM of 22 CLL samples (P < .001, paired Student t test). (E) Effect of abexinostat for 36 hours on BTK protein levels. Data represent mean ± SEM of 60 CLL samples (P < .001, Wilcoxon signed rank test). ***P ≤ .001.