Page 179 - 2014 Printable Abstract Book
P. 179
administered prior to irradiation. ABS3. Filgrastim improves survival after lethal irradiation by improving
myelopoiesis and neutrophil recovery, and ABS4. Filgrastim is equally effective across all species. We
tested a few of these absolutes with the following outcome. ABS1. A single dose of filgrastim can
significantly improve survival of lethally (9.25 Gy) irradiated CD2F1 mice (0.34 mg/kg, 71% survival for
filgrastim-treated group Vs 38% in control). The optimum post-irradiation schedule is 0.17 mg/kg
filgrastim administered subcutaneously on days 1, 2 and 3 post-TBI. Unlike conventional studies, we did
not see an improvement in survival when dosing is continued for 10 or 14 days post-TBI. This schedule
has demonstrable efficacy in multiple mouse strains (C57BL/6 and B6C3F1), denoting that the effect is not
strain-specific. ABS2. Pre-treatment (24 h before exposure) with a single dose of 0.34 mg/kg filgrastim
protects against radiation lethality. ABS3. Improvement in 30 d survival is observed between 9-15 d for
LD-70/30 irradiated mice, while hematopoietic recovery is observed between 14 and 20 days even in
sublethally irradiated mice (7 Gy), showing a disparity between hematopoiesis and survival; suggesting
that filgrastim may play a non-hematopoietic role in ARS. ABS4. While filgrastim is effective in mice, dogs,
mini-pigs and primates, we observe a negative effect with longer dosing schedules in our mouse model
(10 doses, 0.17 mg/kg filgrastim); this effect is abrogated by the use of rodent specific G-CSF (mouse
specific G-CSF, 0.17 mg/kg, 10 once daily dose after exposure to 9.25 Gy).
These data demonstrate the necessity to further optimize filgrastim schedules for maximum survival
benefit and to pursue non-conventional, non-hematopoietic markers for likely targets of mitigation by the
drug.
(PS2-75) Delta-tocotrienol protects mice and human CD34+ cells from radiation injury through
suppression of IL-1β-induced NFκB/miR-30 signaling. Xiang-Hong Li, Master; Cam T. Ha, Doctoral; Dadin
Fu, Doctoral; Mang Xiao, MD, Armed Forces Radiation Research Institute, Bethesda, MD
MicroRNAs (miRNAs) are short, non-coding RNA molecules which regulate specific target
messenger RNA (mRNA) and result in translational repression or target mRNA degradation and gene
silencing. We have reported that miR-30c plays a key role in radiation-induced human hematopoietic cell
damage through repression of survival factor REDDI expression. Here, we further evaluated radiation-
induced miR-30 expression and mechanisms of delta-tocotrienol (DT3), a radiation countermeasure
candidate, for regulating miR-30 in a mouse model and human hematopoietic CD34+ cells. CD2FI mice
were exposed to 0 (control), 7, 8, 10, 11, or 12 Gy and CD34+ cells were irradiated with 0 or 2 Gy of gamma
radiation. Single doses of DT3 (75 mg/kg, subcutaneous injection for mouse and 2 µM for CD34+ cell
culture) were administrated 24 h before irradiation. Mouse bone marrow (BM), jejunum, kidney, liver and
serum as well as CD34+ cells were collected at 1, 4, 8 and 24 h after irradiation to determine apoptotic
markers (TUNEL assay and γ-H2AX), pro-inflammatory cytokine and miRNA expression, clonogenicity and
stress response protein expression. The Results demonstrated that radiation-induced cell damage and
pro-inflammatory cytokine interleukin (IL)-1β release are pathological states that lead to an increase of
miR-30b and miR-30c expression and secretion in mouse tissues and serum and in human CD34+ cells. In
addition, acute secretion of extracellular miR-30b and miR-30c in mouse serum after radiation was stable
and tightly correlated with total-body gamma radiation-induced tissue injury. DT3 suppressed IL-1β and
miR-30 expression in mouse tissues and serum, and inhibited radiation-induced apoptosis in mouse BM
and jejunum cells. Addition of DT3 in CD34+ cell culture before radiation resulted in significantly increased
colony numbers compared with vehicle-treated controls. Furthermore, anti-IL-1β antibody
downregulated NFkBp65 phosphorylation, inhibited miR-30 expression and protected CD34+ cells from
177 | P a g e
myelopoiesis and neutrophil recovery, and ABS4. Filgrastim is equally effective across all species. We
tested a few of these absolutes with the following outcome. ABS1. A single dose of filgrastim can
significantly improve survival of lethally (9.25 Gy) irradiated CD2F1 mice (0.34 mg/kg, 71% survival for
filgrastim-treated group Vs 38% in control). The optimum post-irradiation schedule is 0.17 mg/kg
filgrastim administered subcutaneously on days 1, 2 and 3 post-TBI. Unlike conventional studies, we did
not see an improvement in survival when dosing is continued for 10 or 14 days post-TBI. This schedule
has demonstrable efficacy in multiple mouse strains (C57BL/6 and B6C3F1), denoting that the effect is not
strain-specific. ABS2. Pre-treatment (24 h before exposure) with a single dose of 0.34 mg/kg filgrastim
protects against radiation lethality. ABS3. Improvement in 30 d survival is observed between 9-15 d for
LD-70/30 irradiated mice, while hematopoietic recovery is observed between 14 and 20 days even in
sublethally irradiated mice (7 Gy), showing a disparity between hematopoiesis and survival; suggesting
that filgrastim may play a non-hematopoietic role in ARS. ABS4. While filgrastim is effective in mice, dogs,
mini-pigs and primates, we observe a negative effect with longer dosing schedules in our mouse model
(10 doses, 0.17 mg/kg filgrastim); this effect is abrogated by the use of rodent specific G-CSF (mouse
specific G-CSF, 0.17 mg/kg, 10 once daily dose after exposure to 9.25 Gy).
These data demonstrate the necessity to further optimize filgrastim schedules for maximum survival
benefit and to pursue non-conventional, non-hematopoietic markers for likely targets of mitigation by the
drug.
(PS2-75) Delta-tocotrienol protects mice and human CD34+ cells from radiation injury through
suppression of IL-1β-induced NFκB/miR-30 signaling. Xiang-Hong Li, Master; Cam T. Ha, Doctoral; Dadin
Fu, Doctoral; Mang Xiao, MD, Armed Forces Radiation Research Institute, Bethesda, MD
MicroRNAs (miRNAs) are short, non-coding RNA molecules which regulate specific target
messenger RNA (mRNA) and result in translational repression or target mRNA degradation and gene
silencing. We have reported that miR-30c plays a key role in radiation-induced human hematopoietic cell
damage through repression of survival factor REDDI expression. Here, we further evaluated radiation-
induced miR-30 expression and mechanisms of delta-tocotrienol (DT3), a radiation countermeasure
candidate, for regulating miR-30 in a mouse model and human hematopoietic CD34+ cells. CD2FI mice
were exposed to 0 (control), 7, 8, 10, 11, or 12 Gy and CD34+ cells were irradiated with 0 or 2 Gy of gamma
radiation. Single doses of DT3 (75 mg/kg, subcutaneous injection for mouse and 2 µM for CD34+ cell
culture) were administrated 24 h before irradiation. Mouse bone marrow (BM), jejunum, kidney, liver and
serum as well as CD34+ cells were collected at 1, 4, 8 and 24 h after irradiation to determine apoptotic
markers (TUNEL assay and γ-H2AX), pro-inflammatory cytokine and miRNA expression, clonogenicity and
stress response protein expression. The Results demonstrated that radiation-induced cell damage and
pro-inflammatory cytokine interleukin (IL)-1β release are pathological states that lead to an increase of
miR-30b and miR-30c expression and secretion in mouse tissues and serum and in human CD34+ cells. In
addition, acute secretion of extracellular miR-30b and miR-30c in mouse serum after radiation was stable
and tightly correlated with total-body gamma radiation-induced tissue injury. DT3 suppressed IL-1β and
miR-30 expression in mouse tissues and serum, and inhibited radiation-induced apoptosis in mouse BM
and jejunum cells. Addition of DT3 in CD34+ cell culture before radiation resulted in significantly increased
colony numbers compared with vehicle-treated controls. Furthermore, anti-IL-1β antibody
downregulated NFkBp65 phosphorylation, inhibited miR-30 expression and protected CD34+ cells from
177 | P a g e
