The effects of knockdown of wild-type survivin, survivin-2B or survivin-delta3 on the radiosensitization in a soft tissue sarcoma cells in vitro under different oxygen conditions.
The inhibitor of apoptosis wild-type survivin is a multifunctional protein that suppresses apoptosis and regulates cell cycle progression. An association between wild-type survivin expression and radiosensitivity has been described in different tumor cells. The effects of siRNA-induced knockdown of wild-type survivin and survivin-splice variants survivin-2B and survivin-Delta3 were investigated under normoxic and hypoxic conditions in the human sarcoma cell line US 8-93 (mutant p53). Inhibition of the survivin isoforms by siRNA resulted in a decrease of target mRNA down to 14-70% compared to cells treated with control siRNA independent of the oxygen level. The mRNA expression of survivin isoforms was decreased by the factor of 1-12 when the cells were cultivated under hypoxic conditions. Moreover, the knockdown of wild-type survivin reduced colony formation independent of oxygen concentration down to 70% and induced formation of polyploid cells. Less reduction of plating efficiency was observed after specific knockdown of survivin-2B and survivin-Delta3 under hypoxic or normoxic conditions. A knockdown of wild-type survivin, survivin-Delta3 and survivin-2B isoforms in combination with irradiation caused no radiosensitization in cell line US 8-93, neither under hypoxic nor under normoxic conditions tested in the colony-forming assay. However, knockdown of wild-type survivin caused radiosensitization in the megacolony assay.
Kappler
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M
Department of Radiotherapy, Faculty of Medicine, University of Halle-Wittenberg, Halle/Saale, Germany. matthias.kappler@medizin.uni-halle.de
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Taubert
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Greither
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Bartel
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Dellas
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Hänsgen
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Trott
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Bache
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D002453:Cell Cycle / Q000235:genetics* / Q000528:radiation effects*; D015687:Cell Hypoxia / Q000235:genetics / Q000528:radiation effects; D045744:Cell Line, Tumor; D005720:Gamma Rays; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D010100:Oxygen / Q000378:metabolism*; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000235:genetics*; D011836:Radiation Tolerance / Q000235:genetics*; D012509:Sarcoma / Q000235:genetics* / Q000378:metabolism / Q000532:radiotherapy; D000077022:Survivin
C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000077022:Survivin; D010100:Oxygen