1. HIF-1 Alpha Regulates the Response of Primary Sarcomas to Radiation Therapy through a Cell Autonomous Mechanism.
- Author
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Zhang M, Qiu Q, Li Z, Sachdeva M, Min H, Cardona DM, DeLaney TF, Han T, Ma Y, Luo L, Ilkayeva OR, Lui K, Nichols AG, Newgard CB, Kastan MB, Rathmell JC, Dewhirst MW, and Kirsch DG
- Subjects
- Animals, Cell Line, Tumor, Chemoradiotherapy, Gene Knockdown Techniques, Humans, Hypoxia-Inducible Factor 1, alpha Subunit deficiency, Hypoxia-Inducible Factor 1, alpha Subunit genetics, Mice, Mitochondria metabolism, Mitochondria radiation effects, Mitochondrial Size genetics, Mitochondrial Size radiation effects, Radiation Tolerance genetics, Radiation Tolerance radiation effects, Sarcoma genetics, Sarcoma pathology, Treatment Outcome, Up-Regulation drug effects, Up-Regulation radiation effects, Hypoxia-Inducible Factor 1, alpha Subunit metabolism, Sarcoma metabolism, Sarcoma radiotherapy
- Abstract
Hypoxia is a major cause of radiation resistance, which may predispose to local recurrence after radiation therapy. While hypoxia increases tumor cell survival after radiation exposure because there is less oxygen to oxidize damaged DNA, it remains unclear whether signaling pathways triggered by hypoxia contribute to radiation resistance. For example, intratumoral hypoxia can increase hypoxia inducible factor 1 alpha (HIF-1α), which may regulate pathways that contribute to radiation sensitization or radiation resistance. To clarify the role of HIF-1α in regulating tumor response to radiation, we generated a novel genetically engineered mouse model of soft tissue sarcoma with an intact or deleted HIF-1α. Deletion of HIF-1α sensitized primary sarcomas to radiation exposure in vivo. Moreover, cell lines derived from primary sarcomas lacking HIF-1α, or in which HIF-1α was knocked down, had decreased clonogenic survival in vitro, demonstrating that HIF-1α can promote radiation resistance in a cell autonomous manner. In HIF-1α-intact and -deleted sarcoma cells, radiation-induced reactive oxygen species, DNA damage repair and activation of autophagy were similar. However, sarcoma cells lacking HIF-1α had impaired mitochondrial biogenesis and metabolic response after irradiation, which might contribute to radiation resistance. These results show that HIF-1α promotes radiation resistance in a cell autonomous manner.
- Published
- 2015
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