Induction of Non-Targeted Stress Responses in Mammary Tissues by Heavy Ions

• Published in: PloS one 2015-08, Vol.10 (8), p.e0136307-e0136307
• Main Authors: Wang, Tony J C, Wu, Cheng-Chia, Chai, Yunfei, Lam, Roy K K, Hamada, Nobuyuki, Kakinuma, Shizuko, Uchihori, Yukio, Yu, Peter K N, Hei, Tom K
• Format: Article
• Language: English
• Subjects: 8-Hydroxydeoxyguanosine; Animals; Antibodies; Apoptosis; Argon; Argon ions; Biological effects; Breast; Cancer therapies; Carbon; Caspase; Caspase 3 - genetics; Caspase 3 - metabolism; Caspase-3; Cyclooxygenase 2 - genetics; Cyclooxygenase 2 - metabolism; Cyclooxygenase-2; Cysteine proteinase; Damage assessment; Deoxyguanosine - analogs & derivatives; Deoxyguanosine - metabolism; Deoxyribonucleic acid; DNA; DNA Damage; Exposure; Female; Fibroblasts; Heavy Ions; Histone H2A; Histones - metabolism; In vivo methods and tests; Ionizing radiation; Ions; Irradiation; Mammary Glands, Animal - radiation effects; Materials science; Medical research; Mice; Mutagenesis; Oncology; Radiation; Radiation damage; Radiation effects; Radiation shielding; Radiation therapy; Relative biological effectiveness (RBE); Side effects; Stress, Physiological; Tissues; Transgenic animals; Transgenic mice; X-rays
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0136307

Side effects related to radiation exposures are based primarily on the assumption that the detrimental effects of radiation occur in directly irradiated cells. However, several studies have reported over the years of radiation-induced non-targeted/ abscopal effects in vivo that challenge this paradigm. There is evidence that Cyclooxygenase-2 (COX2) plays an important role in modulating non-targeted effects, including DNA damages in vitro and mutagenesis in vivo. While most reports on radiation-induced non-targeted response utilize x-rays, there is little information available for heavy ions. Adult female transgenic gpt delta mice were exposed to an equitoxic dose of either carbon or argon particles using the Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences (NIRS) in Japan. The mice were stratified into 4 groups of 5 animals each: Control; animals irradiated under full shielding (Sham-irradiated); animals receiving whole body irradiation (WBIR); and animals receiving partial body irradiation (PBIR) to the lower abdomen with a 1 x 1 cm2 field. The doses used in the carbon ion group (4.5 Gy) and in argon particle group (1.5 Gy) have a relative biological effectiveness equivalent to a 5 Gy dose of x-rays. 24 hours after irradiation, breast tissues in and out of the irradiated field were harvested for analysis. Induction of COX2, 8-hydroxydeoxyguanosine (8-OHdG), phosphorylated histone H2AX (γ-H2AX), and apoptosis-related cysteine protease-3 (Caspase-3) antibodies were examined in the four categories of breast tissues using immunohistochemical techniques. Analysis was performed by measuring the intensity of more than 20 individual microscopic fields and comparing the relative fold difference. In the carbon ion group, the relative fold increase in COX2 expression was 1.01 in sham-irradiated group (p > 0.05), 3.07 in PBIR (p < 0.05) and 2.50 in WBIR (p < 0.05), respectively, when compared with controls. The relative fold increase in 8-OHdG expression was 1.29 in sham-irradiated (p > 0.05), 11.31 in PBIR (p < 0.05) and 11.79 in WBIR (p < 0.05), respectively, when compared with controls. A similar increase in γ-H2AX expression was found in that, compared to controls, the increase was 1.41 fold in sham-irradiated (p > 0.05), 8.41 in PBIR (p < 0.05) and 10.59 in WBIR (p < 0.05). Results for the argon particle therapy group showed a similar magnitude of changes in the various biological endpoints examined. There was no