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Oncol Rep. 2014 May;31(5):2147-56. doi: 10.3892/or.2014.3089. Epub 2014 Mar 13.

MicroRNA expression profiles in human breast cancer cells after multifraction and single-dose radiation treatment.

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Department of Radiation Oncology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, R.O.C.
Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan, R.O.C.
Genomics and Proteomics Core Laboratory, Department of Medical Research, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan, R.O.C.
Biodiversity Research Center, Academia Sinica, Taipei, Taiwan, R.O.C.
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, R.O.C.
Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, R.O.C.
Department of Safety, Health and Environmental Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung, Taiwan, R.O.C.
Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, R.O.C.


MicroRNAs (miRNAs) are small non-coding RNAs that contribute to modulating signaling pathways after radiation exposure and have emerged as a potential therapeutic target or biomarker in the radiation response of cancer. Exposing breast cancer cells to single-dose (SD) or multifractionated (MF) radiation may affect the cells differently. However, the roles of miRNAs in breast cancer cells after the response to SD or MF is not thoroughly understood. Therefore, the purpose of the present study was to comprehensively investigate the response of miRNAs in MDA-MB-361 by using various radiation exposing protocols. Our results revealed that only a small fraction of miRNAs exhibiting differential expressions (>1.5‑fold) was identified after MDA-MB-361 cells were exposed to SD (10 Gy) or MF radiation (2 Gy x 5 MF). In addition, we observed that several miRNAs in the MDA-MB-361 cells frequently exhibited differential responses to various types of radiation treatment. Among these miRNAs, the expression levels of an oncogenic miR-17-92 cluster increased following SD radiation treatment. Conversely, miR-19a-3p, miR-20a-5p, and miR-19b-3p expressions were inhibited by >1.5-fold in the following MF treatment. Further analysis of the miR-17-92 cluster expression levels revealed that miR-17, miR-18a, miR-19a/b and miR-20a were significantly overexpressed and miR-92a was downregulated in breast cancer. Functional annotation demonstrated that target genes of the miR-17-92 cluster were predominantly involved in the regulation of radiation-associated signal pathways such as mitogen-activated protein kinase (MAPK), ErbB, p53, Wnt, transforming growth factor-β (TGF-β), mTOR signaling pathways and cell cycles with an FDR <0.05. Overall, the results of the present study revealed distinct differences in the response of miRNAs to SD and MF radiation exposure, and these radiation-associated miRNAs may contribute to radiosensitivity and can be used as biomarkers for radiotherapy.

[Indexed for MEDLINE]

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