cell counting, and the left lungs were collected for hydroxyproline measurement or fixed for Masson trichrome staining. The plasm transforming growth factor b ...
Proceedings of the 50th Annual ASTRO Meeting
3174
Acetylated Resveratrol: A New Small Molecule Radioprotector
K. Koide, M. W. Epperly, D. Franicola, T. Dixon, X. Zhang, P. Komanduri, B. Greenberger, J. S. Greenberger University of Pittsburgh Cancer Inst., Pittsburgh, PA Purpose/Objective(s): New small molecules with radioprotective capacity are required for treatment of radiation spills or as countermeasures against radiological terrorism. Small molecules which can be easily stored, easily transported, inexpensive to produce and easily administered are optimal. We have tested the dietary component resveratrol and an acetylated moiety for protection of cells against radiation damage. Materials/Methods: Irradiation survival curves were carried out with resveratrol or acetylated resveratrol. Cells from the murine hematopoietic progenitor cell line 32D cl 3 were incubated with resveratrol or acetylated resveratrol (10 mM) for 1 hr and then were irradiated to doses ranging from 0 to 8 Gy. The cells were suspended in methylcellulose, incubated for 7 days at 37oC, colonies of greater than 50 cells counted and data analyzed by linear quadratic and single-hit, multi-target models. In vivo studies were performed by injecting intraperitoneally female C57BL/6NHsd mice either 10 minutes before or 10 minutes after an LD50/30 dose of 9.5 Gy total body irradiation. We compared resveratrol or acetylated resveratrol (1, 10, or 25 mg/kg). The mice were followed for irradiation induced hematopoietic syndrome. Results: Incubation of 32D cl 3 cells in resveratrol or acetylated resveratrol before irradiation resulted in an increase in radiation resistance by an increased shoulder on the survival curve of 33.2 ± 5.7 or 37.5 ± 9.9, respectively, compared to 6.9 + 1.8 for 32D cl 3 cells (p = 0.0122 or 0.0072, respectively). The mice injected with acetylated-resveratrol had increased survival at 10 and 25 mg/kg compared to control irradiated mice (p\0.0001 or = 0.0004, respectively). In contrast, resveratrol did not increase mouse survival. Neither resveratrol nor acetylated resveratrol were effective mitigators when given after irradiation. Conclusions: Acetylated resveratrol administered before irradiation in a mouse model is radioprotective. Further studies are in progress to determine if acetylated resveratrol can be translated to clinical use as a radioprotective agent. Author Disclosure: K. Koide, None; M.W. Epperly, None; D. Franicola, None; T. Dixon, None; X. Zhang, None; P. Komanduri, None; B. Greenberger, None; J.S. Greenberger, None.
3175
Effects of Pirfenidone on Prevention of Radiation-induced Lung Toxicity - Results of an Animal Experiment
J. Wei, J. Heng, Y. Weizhi, W. Luhua Cancer Hospital, China Purpose/Objective(s): Pirfenidone (5-methyl-1-phenyl-2-[1H]-pyridone), is a novel experimental drug used as anti-fibrotic agent. This study was undertaken to investigate the effect of pirfenidone on prevention of radiation-induced lung toxicity. Materials/Methods: Male BALB/C mice were randomized into 4 groups: Control (group C); Radiation alone (group R); Pirfenidone alone (group P); Radiation + Pirfenidone (group R+P). Either sham irradiation (groups C and P) or single fraction of 12 Gy to whole thorax (groups R and R+P) were given to the animals. The animals were fed with control diet or same diet plus 0.5% Pirfenidone from 3 days prior to irradiation to 12 weeks after irradiation. The animals (6-8 mice per group) were sacrificed 1, 2, 3, 4, 5, 6 months after irradiation. Bronchoalveolar lavage fluid (BALF) from the right lungs was collected for detection of cell counting, and the left lungs were collected for hydroxyproline measurement or fixed for Masson trichrome staining. The plasm transforming growth factor b (TGF-b) was measured with ELISA method. T test and chi-square were used for statistical analysis. Results: Macrophages in BALF were dramatically increased in the R and R+P groups at 4, 5, and 6 months after irradiation, but the number of macrophages were lower in group R than in group R+P (18.51104/ml vs. 4.50 104/ml p = 0.005; 60.61104/ml vs. 23.05104/ml p = 0.046; 46.24104/ml vs. 35.00104/ml p = 0.305). Plasma TGF-b level in group R+P was lower comparing to that in group R at 3, 4, and 5 months after irradiation, but not statistically significant (3.48 pg/ml vs. 5.03 pg/ml p = 0.223; 3.82pg/ml vs. 5.31 pg/ml p = 0.666; 3.31pg/ml vs. 4.27pg/ml p = 0.310). Total lung hydroxyproline content, an index of fibrosis, was gradually increased with time in both group R and group R+P. But the level in R+P group were 21%, 24% lower comparing to group R at 4 and 5 months (86.1 mg/lung vs. 67.7 mg/lung p = 0.007; 104.1 mg/lung vs. 79.2 mg/lung p = 0.001). Based on Masson trichrome staining, we found that pirfenidone can ameliorate the severity of lung fibrosis at 4, 5, and 6 months after irradiation, the mean fibrosis score was higher in group R than in group R+P (47.50 vs. 20.30 p = 0.003; 47.91 vs. 29.15 p = 0.039; 42.50 vs. 19.46 p = 0.000). Conclusions: Pirfenidone has a protective effect on radiation-induced lung toxicity in mice. Author Disclosure: J. Wei, None; J. Heng, None; Y. Weizhi, None; W. Luhua, None.
3176
Valproic Acid Shows Normal Tissue Protection in a Rat Spinal Cord Model
D. Kornguth1, J. Su2, X. Li2, K. Ang1, S. Blaney2, C. Lau2, S. Woo1 1
M.D. Anderson Cancer Center, Houston, TX, 2Texas Children’s Hospital, Houston, TX
Purpose/Objective(s): Valproic Acid (VPA) is a well-tolerated anticonvulsant that has demonstrated growth inhibition properties in some CNS tumor models, yet no studies have yet evaluated what effect VPA has on irradiated normal CNS tissue. This study was designed to what effect, if any, VPA has on irradiated CNS tissue in an established rat spinal cord injury model. Materials/Methods: A total of 48 experimental and 29 control Fisher rats were irradiated in 2 equal fractions over two days to cumulative doses of 30, 32, 34, 36, 38, and 40 Gy to a 1.5 cm segment of the cervical spinal cord using a single AP field. The experimental group had ALZET osmotic pumps 3 days before irradiation, and VPA serum concentrations were measured in a sample of rats on days 4, 5, and 8 after pump implantation. The rats were maintained in our animal care facility and followed for signs of paresis. When veterinary staff deemed that rats paralyzed, they were sacrificed and the spinal cords harvested for histologic evaluation. The time to paralysis was analyzed between the experimental and control group with animals dying of other causes censored.
S697
I. J. Radiation Oncology d Biology d Physics
S698
Volume 72, Number 1, Supplement, 2008
Results: VPA had significantly longer paralysis-free probability compared to the control groups (log rank test p \0.001 for both 38 Gy and 40 Gy). The LD50 for Control group was 36.9 Gy. In the VPA group, we did not reach LD50 with doses that went up to 40 Gy. Conclusions: VPA administered before and during irradiation demonstrates protection from late radiation damage in the rat spinal cord. Author Disclosure: D. Kornguth, None; J. Su, None; X. Li, None; K. Ang, None; S. Blaney, None; C. Lau, None; S. Woo, None.
3177
Serum Amyloid P Inhibits Radiation-induced Mucositis
L. A. Murray1, M. S. Kramer1, B. Watkins2, E. Fey2, D. P. Hesson1, S. T. Sonis3 1
Promedior, Malvern, PA, 2Biomodels, Boston, MA, 3Brigham and Women’s Hospital, Boston, MA
Background: Oral mucositis is a common side effect following chemotherapy and radiotherapy. The ensuing injury significantly impairs the patients’ quality of life and can hamper the scheduled course of therapy, thus reducing efficacy of treatment. Oral mucositis is characterized by a complex pathoetiology in which induction of a series of biologic pathways within the submucosa compliments direct clonogenic epithelial cell death to result in pronounced mucosal ulceration. Fibrotic remodeling of the surrounding tissue often ensues, resulting in a loss of elasticity that produces detrimental functional consequences. Serum amyloid P (SAP) is a serum protein shown previously to reduce experimental models of cardiac and pulmonary fibrosis, in part by reducing the infiltration of bone marrow-derived collagen I+ cells. Purpose/Objective(s): Here we utilized an established hamster cheek pouch model of radiation-induced mucositis to determine if SAP treatment impacts either the clinical or pathological hallmarks of mucositis. Materials/Methods: Hamsters received a single dose of radiation (40 Gy) to the left everted cheek pouch at Day 0. In the SAP treated group, animals received SAP (2 mg/kg, i.p.) every other day from day 0 - Day 12. Beginning on Day 6, and continuing on alternate days until the completion of the experiment (Day 28), photographs of each cheek pouch were taken. At the end of the experiment, photographs were scored for mucositis severity was by observers blinded to the study, using a validated scoring 6 point scheme ranging from 0 (normal tissue, no mucositis) to 5 (complete ulceration). Results: The SAP treatment attenuated the profile of radiation-induced mucositis by delaying the time of onset, reducing the peak value and enhancing the resolution of the pathology. The peak mucositis score was reduced by approximately 0.5 grade in SAPtreated animals. The percentage of animal days with a score of 3 or greater was 21.7% in the SAP treated group compared to 35% in the saline control group (p = 0.002). At the histological level, SAP also inhibited the extent of tissue remodeling, as determined by trichrome staining of collagen. Conclusions: The SAP treatment significantly attenuated radiation-induced injury, suggesting this may be a useful therapy for the palliation of side effects observed during head & neck cancer treatment. Author Disclosure: L.A. Murray, Promedior, A. Employment; M.S. Kramer, Promedior, A. Employment; B. Watkins, None; E. Fey, None; D.P. Hesson, Promedior, A. Employment; S.T. Sonis, Promedior, F. Consultant/Advisory Board.
3178
Radioprotection of Small Intestines and Bone Marrow by Inhibition of Glycogen Synthase Kinase-3 beta (GSK-3b)
D. Thotala, D. Hallahan, E. Yazlovitskaya Vanderbilt University, Nashville, TN Background: Radiation-induced impairments are dose-dependent consequences of cancer therapy. Glycogen Synthase Kinase-3 beta (GSK-3b) has emerged as a key regulator of neuronal, endothelial, hepatocyte, fibroblast, and astrocyte death. We studied GSK-3b inhibitors to determine whether they are suitable radioprotectors in small intestines and bone marrow. Purpose/Objective(s): Development of new treatments is critical to effective protection against radiation-induced injury. The physiopathological aspects of normal tissue toxicity have been widely explored; however, none of these descriptive findings has led to the development of effective therapeutic strategies. Our studies have focused on the radioprotective effects of inhibition of GSK-3b. In the earlier study we have shown that small molecule inhibitors of GSK-3b protect hippocampal neurons from radiation-induced apoptosis. Extending our study here we show protective effect of GSK-3b inhibitors in small intestines and bone marrow of irradiated mouse models. Materials/Methods: Ten-week-old C57BL6 mice were treated with DMSO or 1.0 mg/kg SB415286 intraperitoneally for 3 consecutive days followed by a single dose of 4, 8, or 15 Gy of whole body radiation. The femurs from treated mice were fixed in 10% paraformaldehyde and decalcified in 8% hydrochloric acid/formic acid (1:1). The proximal jejunum of the small intestine was also fixed in 10% paraformaldehyde. The decalcified femurs and the jejunum were embedded in paraffin wax using standard techniques. The four micron femur and intestine sections were either stained using TUNEL kit or with hematoxylin. Apoptosis was evaluated by comparing the average number of TPC (TUNEL positive cells) per HPF. Results: Mice pretreated with SB415286 prior irradiation showed significantly less TUNEL-positive cells (\4 and 8 TPC for 8 Gy; \15 and 10 TPC for 15 Gy; for 4 and 12 h, respectively) as compared to irradiated animals (6 and 15 TPC for 8 Gy; 26 and 28 TPC for 15 Gy; for 4 and 12 h, respectively), indicating possible radioprotective effect of GSK-3b inhibitors from radiation-induced damage of gastrointestinal tract. According to the cell position in mice small intestine crypt, the majority of the affected cells are stem cells. Additionally, density of the bone marrow cells in the cavity of the femur from mice treated with SB415286 prior to radiation was significantly higher as compared to mice treated with radiation alone. Conclusions: Our observations suggest the protective effect of GSK-3b inhibition from radiation-induced death in gastrointestinal tract and bone marrow. We propose that small molecule inhibitors of GSK-3b could have a therapeutic role in protecting from radiation-induced injury. Author Disclosure: D. Thotala, None; D. Hallahan, None; E. Yazlovitskaya, None.
