Effects of lipids and inhibitors of SREBF1 activation on the expression of
MEF2D-fusion protein and the therapeutic efficacies of inhibitors. A,
Incubation of MEF2D-ALL cells with cholesterol diminished the expression of
MEF2D-fusion protein. Cells were cultured in the presence (+) or absence (−) of
cholesterol (10 μg/mL cholesterol and 2 μg/mL 25-hydroxycholesterol) for 3 days.
Expression of the indicated proteins was analyzed by Western blotting. B,
Treatment of five MEF2D-ALL cell lines with fatostatin, FGH10019, and betulin reduced
the protein expression of MEF2D-fusion and SREBF1. Cells were treated with fatostatin
(3 μmol/L), FGH10019 (3 μmol/L), or betulin (10 μmol/L) for 3 days. All treatments
reduced SREBF1 expression. + and – denote treatment with the indicated drug and
vehicle, respectively. C, Treatment of Kasumi-7 cells with the indicated
inhibitors of SREBF1 activation, as in B, reduced the expression of BCL6,
FOS, and EGR1. D, Fatostatin, FGH10019, and betulin selectively inhibited
MEF2D-ALL cell growth. Cells were treated with varying concentrations of the drugs for
3 days as indicated. Cell growth was monitored and compared with vehicle treatment as
a control. The values relative to the control are presented as means ± SDs
(n = 3). E, FGH10019 retards Kasumi-7 cell growth and
prolongssurvival in mice. Immunodeficient mice were transplanted with Kasumi-7 cells
engineered to express GFP and subsequently treated with FGH10019 (25 mg/kg/day, 6 days
per week) or vehicle (n = 5 each). Peripheral blood was collected at
8 and 11 weeks after transplantation and analyzed to determine the %GFP-expressing
cells (left). The difference in %GFP between samples from FGH10019- and
vehicle-treated mice was statistically significantly different (Wilcoxon rank-sum
test; top right). The estimated Kaplan–Meier survival curves of FGH10019- and
vehicle-treated mice were also statistically significantly different (log-rank test;
bottom right). F, Pre-BCR expression in the indicated cells after
treatment with FGH10019 (3 μmol/L) or vehicle for 3 days in culture.