Page 243 - 2014 Printable Abstract Book
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treated with 1 μM VE-821 were irradiated with either 290 MeV/n accelerated carbon ions using the Heavy
Ion Medical Accelerator in Chiba (HIMAC) or X-ray using a TITAN irradiator at 200 kVp and 20 mA, at a
dose rate of 1 Gy/min. Cells were pre-incubated with 1 μM VE-821 for 1 hour before irradiation. Cell cycle
analysis, DNA DSBs, and cell survival were evaluated with a flow cytometer (BD FACSCalibur), an
immunofluorescence, and a colony formation assay, respectively. ATR kinase inhibitor, VE-821 showed
abrogation of G2 cell cycle checkpoint and decreased cellular survival after both carbon and X-ray
irradiation; this was particularly notable in HeLa cells. Remaining number of γH2AX foci, DNA DSB marker,
24 hours after irradiation was higher in these cancer cells treated with VE-821 than that with radiation
alone. In normal cells, the remaining number of foci was not as high as cancer cells after the combined
treatment. These results suggest that VE-821 forces irradiated cells to enter M phase and attempt to
divide into daughter cells with remaining DNA damages. Consequently, their cellular radio-sensitivities
were enhanced, presumably because of mitotic catastrophe. In conclusion, ATR inhibitor would be an
effective tumor radio-sensitizer with carbon ion irradiation.
(PS4-15) Granulocyte colony-stimulating factor improves hepatic and renal mitochondrial functions
after whole body irradiation. Steven B. Zhang, DVM, PhD; Mei Zhang, MD; Amy Zhang, RN; Steven G.
Swarts, PhD; Zhenhuan Zhang, MD, PhD; Shanmin Yang, MD; and Paul Okunieff, MD, UF Health Cancer
Center, Gainesville, FL
Objective: Acute radiation syndrome occurs in humans following whole-body or significant
partial-body irradiation of greater than 1 Gy when delivered over a short period of time. Granulocyte
colony-stimulating factor (G-CSF) is a glycoprotein that stimulates the hematopoietic system to produce
granulocytes and stem cells and release them into the bloodstream. G-CSF also allows greater survival,
proliferation, differentiation, and function of neutrophil precursors and mature neutrophils with or
without radiation. G-CSF has been used therapeutically to accelerate recovery from cytopenia after
chemotherapy, radiotherapy, and accidental irradiation. The many mechanisms by which G-CSF might
protect against radiotoxicity are still to be elucidated. As mitochondrial function plays an important role
in cell health and apoptosis, we studied the effect of G-CSF on irradiated mitochondria. Methods: G-CSF
was administered intramuscularly to C57BL/6 and NIH Swiss mice at a single dose (20 µg/kg) 2 hours after
irradiation. Organs were collected at various times ranging from 9 hr to 35 days after irradiation. Swelling
of hepatic and renal mitochondria was assessed by changes in light absorbance at 540 nm.
Results: (1) The hepatic and renal mitochondria in C57BL/6 and NIH Swiss mice exhibited significant
baseline differences in swelling. Hepatic mitochondria were significantly more sensitive than renal
mitochondria to calcium at various concentrations. (2) Radiation-damaged mitochondrial permeability
transition (mPT) of hepatic and renal mitochondria was observed 9 hr after irradiation.
(3) Radiation-induced mPT damage was dose dependent. (4) G-CSF decreased radiation-induced mPT
damage in hepatic and renal mitochondria (9 and 24 hr after irradiation). (5) G-CSF improved recovery of
radiation-induced mPT in hepatic and renal mitochondria 28 and 35 days after irradiation. (6) Cyclosporin
A (a specific mPT blocker) reduced calcium responses in hepatic and renal mitochondria.
Conclusion: Radiation-induced mitochondrial damage was reduced in the kidneys and livers of mice that
received G-CSF. Mitochondrial functional stabilization may have a role in the mitigation of multi-organ
damage after whole-body irradiation.
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Ion Medical Accelerator in Chiba (HIMAC) or X-ray using a TITAN irradiator at 200 kVp and 20 mA, at a
dose rate of 1 Gy/min. Cells were pre-incubated with 1 μM VE-821 for 1 hour before irradiation. Cell cycle
analysis, DNA DSBs, and cell survival were evaluated with a flow cytometer (BD FACSCalibur), an
immunofluorescence, and a colony formation assay, respectively. ATR kinase inhibitor, VE-821 showed
abrogation of G2 cell cycle checkpoint and decreased cellular survival after both carbon and X-ray
irradiation; this was particularly notable in HeLa cells. Remaining number of γH2AX foci, DNA DSB marker,
24 hours after irradiation was higher in these cancer cells treated with VE-821 than that with radiation
alone. In normal cells, the remaining number of foci was not as high as cancer cells after the combined
treatment. These results suggest that VE-821 forces irradiated cells to enter M phase and attempt to
divide into daughter cells with remaining DNA damages. Consequently, their cellular radio-sensitivities
were enhanced, presumably because of mitotic catastrophe. In conclusion, ATR inhibitor would be an
effective tumor radio-sensitizer with carbon ion irradiation.
(PS4-15) Granulocyte colony-stimulating factor improves hepatic and renal mitochondrial functions
after whole body irradiation. Steven B. Zhang, DVM, PhD; Mei Zhang, MD; Amy Zhang, RN; Steven G.
Swarts, PhD; Zhenhuan Zhang, MD, PhD; Shanmin Yang, MD; and Paul Okunieff, MD, UF Health Cancer
Center, Gainesville, FL
Objective: Acute radiation syndrome occurs in humans following whole-body or significant
partial-body irradiation of greater than 1 Gy when delivered over a short period of time. Granulocyte
colony-stimulating factor (G-CSF) is a glycoprotein that stimulates the hematopoietic system to produce
granulocytes and stem cells and release them into the bloodstream. G-CSF also allows greater survival,
proliferation, differentiation, and function of neutrophil precursors and mature neutrophils with or
without radiation. G-CSF has been used therapeutically to accelerate recovery from cytopenia after
chemotherapy, radiotherapy, and accidental irradiation. The many mechanisms by which G-CSF might
protect against radiotoxicity are still to be elucidated. As mitochondrial function plays an important role
in cell health and apoptosis, we studied the effect of G-CSF on irradiated mitochondria. Methods: G-CSF
was administered intramuscularly to C57BL/6 and NIH Swiss mice at a single dose (20 µg/kg) 2 hours after
irradiation. Organs were collected at various times ranging from 9 hr to 35 days after irradiation. Swelling
of hepatic and renal mitochondria was assessed by changes in light absorbance at 540 nm.
Results: (1) The hepatic and renal mitochondria in C57BL/6 and NIH Swiss mice exhibited significant
baseline differences in swelling. Hepatic mitochondria were significantly more sensitive than renal
mitochondria to calcium at various concentrations. (2) Radiation-damaged mitochondrial permeability
transition (mPT) of hepatic and renal mitochondria was observed 9 hr after irradiation.
(3) Radiation-induced mPT damage was dose dependent. (4) G-CSF decreased radiation-induced mPT
damage in hepatic and renal mitochondria (9 and 24 hr after irradiation). (5) G-CSF improved recovery of
radiation-induced mPT in hepatic and renal mitochondria 28 and 35 days after irradiation. (6) Cyclosporin
A (a specific mPT blocker) reduced calcium responses in hepatic and renal mitochondria.
Conclusion: Radiation-induced mitochondrial damage was reduced in the kidneys and livers of mice that
received G-CSF. Mitochondrial functional stabilization may have a role in the mitigation of multi-organ
damage after whole-body irradiation.
241 | P a g e
