Journal article

Differential effect of parity on rat mammary carcinogenesis after pre- or post-pubertal exposure to radiation

Masaru Takabatake, Kazuhiro Daino, Tatsuhiko Imaoka, Benjamin J Blyth, Toshiaki Kokubo, Yukiko Nishimura, Kaye Showler, Ayaka Hosoki, Hitomi Moriyama, Mayumi Nishimura, Shizuko Kakinuma, Masahiro Fukushi, Yoshiya Shimada

Scientific Reports | Nature Publishing Group | Published : 2018


Radiation exposure during the peri-pubertal period is a proven risk factor for breast cancer, whereas parity is an established protective factor. The present study investigated whether parity imposes differential protective effects against radiation-induced rat mammary carcinoma depending on the age at exposure. Pre- and post-pubertal female rats, irradiated or left unirradiated, were mated and allowed to nurse until weaning or left unmated. Appearance of mammary tumors was monitored, and serum concentrations of estradiol and progesterone were measured following weaning. Carcinomas were evaluated by immunohistochemistry for estrogen receptor, progesterone receptor, and the cell proliferation..

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Awarded by Japan Society for the Promotion of Science

Funding Acknowledgements

The authors thank Dr. Eric J. Grant for critical reading of the manuscript and making helpful suggestions. The authors also thank Dr. Airo Tsubura and Dr. Jose Russo for their kindly informing us about the protocols for Ki-67 and HER2 staining, respectively. We are very grateful to all laboratory members for their assistance and the Laboratory Animal and Genome Sciences Section of National Institute of Radiological Sciences for animal management. The animal tissues used in this study are part of the J-SHARE Project (Japan-StoreHouse of Animal Radiobiology Experiments) under construction by the National Institute of Radiological Sciences. This work was supported in part by a Grant-in-Aid from the Japan Society for the Promotion of Science Fellows (No. 24-7555) to M.T., a Grant-in-Aid for Young Scientists (No. 16K19876) to M.T., and the Program of the Network-type Joint Usage/Research Center for Radiation Disaster Medical Science of Hiroshima University, Nagasaki University, and Fukushima Medical University.