Fig. 4. CREB Inhibition In Vivo.

A) Bioluminescent imaging revealed significantly less disease burden in mice treated with daily intravenous injections of XX-650-23 on treatment days 10, 14 and 17 (DMSO-treated mice, left; XX-650-23-treated mice, right). B) Kaplan-Meier curve analysis demonstrated a significant survival advantage in NSG mice treated with 2.3 mg/kg/day intravenously once a day XX-650-23 (n=10) compared to those treated with vehicle alone (n=10) beginning one day after AML cell injection (p = 0.0027, log-rank tests). C) Kaplan-Meier curve analysis also demonstrated a survival advantage for mice given XX-650-23 (n=10) compared to those treated with vehicle alone (n=8) beginning 7 days after AML cell injection (p=0.0211, log-rank tests). D) RT-PCR showed XX-650-23 elicits the same transcriptional alterations in vivo as observed in vitro. To directly evaluate the effects of XX-650-23 on CREB transcriptional activity in vivo, six NSG mice were injected with 2x10⁶ HL-60 expressing GFP. After a ten-day engraftment period, the mice received three once-daily treatments of either 2.3 mg/kg XX-650-23 or DMSO. The mice were then sacrificed and GFP⁺ bone marrow cells were sorted and analyzed for transcriptional changes in validated CREB target genes. XX-650-23 treatment significantly reduced expression of all genes. Data are graphed as mean ± SEM (n = 3), *p < 0.05; **p < 0.01, t-test.