SB939 corrects pre-mRNA splicing of <i>BIM</i> and induces apoptosis in CML cell lines with the <i>BIM</i> deletion polymorphism.

<p>(A) Ratio of exon 3- to exon 4-containing <i>BIM</i> transcripts, as assayed by qPCR, in K562 CML cell lines without the <i>BIM</i> deletion polymorphism (<i>BIM</i>^<i>i2+/+</i>), as well as those which were heterozygous (<i>BIM</i>^<i>i2+/-</i>) and homozygous for the deletion polymorphism (<i>BIM</i>^<i>i2-/-</i>). Cells were treated for 18 hours with SB939 at the indicated concentrations. (B) Immunoblots showing induction of apoptosis in K562 <i>BIM</i>^<i>i2+/+</i>, <i>BIM</i>^<i>i2+/-</i> <i>and BIM</i>^<i>i2-/-</i>. The data shown are representative of 3 experiments with similar results. Cells were treated for 48hours with SB939 at the indicated concentrations. p-BCR-ABL, phosphorylated BCR-ABL; STAT5, signal transducer and activator of transcription 5; p-STAT5, phosphorylated STAT5; BIMEL, BIM extra long isoform; BIML, BIM long isoform; Cl. CASP3, cleaved CASPASE3; Cl. PARP, cleaved PARP. 48-hour treatment as in A. (C) Apoptotic cell death, as assessed by flow cytometry-based Annexin V assay, in K562 <i>BIM</i>^<i>i2+/+</i>, <i>BIM</i>^<i>i2+/-</i> <i>and BIM</i>^<i>i2-/-</i> cells after 48-hour treatment with SB939. All results are given as the mean ± s.e.m (n = 3). The P values were based on Student’s <i>t</i> test. For (A) and (C), the indicated P values were calculated by comparing to the corresponding DMSO control samples. (A): *P = 0.002, **P = 0.004, ^P = 0.019. (C): *P = 0.0031, **P = 0.02, ***P = 4.4 X 10⁻⁷, ⁺P = 0.037, ⁺⁺P = 3.2 X 10⁻⁶, ^P = 0.0094, ^^P = 7.1 X 10⁻⁴.