Inhibition of hypoxia-inducible factor-1 alpha radiosensitized MG-63 human osteosarcoma cells in vitro.
OBJECTIVE
Hypoxia is a fundamental microenvironmental component of osteosarcoma which induces activation of the hypoxia-inducible factor-1 (HIF-1) pathway. Overexpression of HIF-1α has been linked to tumor resistance to radio- or chemotherapy. However, little is known about the effects of HIF-1α inhibition on hypoxic radioresistance of human osteosarcoma cells. Here, we investigated the effects of HIF-1α inhibition on cell survival and radiosensitivity in the MG-63 human osteosarcoma cell line.


METHODS
HIF-1α inhibition was achieved by small interfering RNA (siRNA) targeting of HIF-1α or via chetomin. Inhibition of the HIF-1 pathway was determined by monitoring the expression levels of HIF-1α, carbonic anhydrase 9 (CA9) and vascular endothelial growth factor (VEGF) using quantitative real-time PCR and Western blot analyses. Clonogenic assay was performed after irradiation (2-10 Gy) to investigate the effect of HIF-1α inhibition on the radiosensitivity of human osteosarcoma cells under normoxic and hypoxic conditions.


RESULTS
Compared to the control groups, treatment with HIF-1α siRNA or chetomin significantly reduced the hypoxia-inducible radioresistance of MG-63 cells. However, siRNA and chetomin showed different effects on the radiosensitivity under normoxic conditions.


CONCLUSIONS
Our results indicate that inhibition of HIF-1α effectively decreases hypoxia-induced transcription and radiosensitizes hypoxic MG-63 human osteosarcoma cells in vitro.
Department of Micro-Orthopedics, Zhongnan Hospital of Wuhan University, Wuhan - China.
Zhu
Z
Jin
Department of Micro-Orthopedics, Zhongnan Hospital of Wuhan University, Wuhan - China.
Yu
Y
Aixi
Department of Micro-Orthopedics, Zhongnan Hospital of Wuhan University, Wuhan - China.
Qi
Q
Baiwen
Department of Micro-Orthopedics, Zhongnan Hospital of Wuhan University, Wuhan - China.
Li
L
Zonghuan
Department of Micro-Orthopedics, Zhongnan Hospital of Wuhan University, Wuhan - China.
Hu
H
Xiang
D015153:Blotting, Western; D001859:Bone Neoplasms / Q000503:physiopathology* / Q000532:radiotherapy; D045744:Cell Line, Tumor; D002470:Cell Survival; D004220:Disulfides / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D026121:Indole Alkaloids / Q000494:pharmacology*; D012516:Osteosarcoma / Q000503:physiopathology* / Q000532:radiotherapy; D034741:RNA, Small Interfering / Q000494:pharmacology*; D011836:Radiation Tolerance / Q000187:drug effects; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D015854:Up-Regulation
D004220:Disulfides; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D026121:Indole Alkaloids; D034741:RNA, Small Interfering; D011838:Radiation-Sensitizing Agents; C001598:chetomin