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HIF-1α inhibition by siRNA or chetomin in human malignant glioma cells: effects on hypoxic radioresistance and monitoring via CA9 expression.

Kessler J, Hahnel A, Wichmann H, Rot S, Kappler M, Bache M, Vordermark D - BMC Cancer (2010)

Bottom Line: In this study, we investigated the effects of the inhibition of HIF-1α on cell survival and radiosensitivity in U251MG and U343MG glioma cells, using two different strategies.However, siRNA and chetomin showed diverse effects on radiosensitivity under normoxic conditions in U251MG (DMF10: 0.86 and 1.35) and U343MG (DMF10: 1.33 and 1.02) cells.Results from this in vitro study suggest that inhibition of HIF-1α is a promising strategy to sensitize human malignant gliomas to radiotherapy and that CA9 could serve as an indicator of effective HIF-1-related radiosensitization.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Radiotherapy, Faculty of Medicine, Martin-Luther-University Halle-Wittenberg, Ernst-Grube-Straße 40, 06097 Halle, Saale, Germany. jacqueline.kessler@medizin.uni-halle.de

ABSTRACT

Background: Hypoxia induces activation of the HIF-1 pathway and is an essential characteristic of malignant gliomas. Hypoxia has been linked to tumor progression, therapy resistance and poor prognosis. However, little is known about the impact of HIF-1α inhibition on radioresistance of malignant glioma.

Methods: In this study, we investigated the effects of the inhibition of HIF-1α on cell survival and radiosensitivity in U251MG and U343MG glioma cells, using two different strategies. HIF-1α inhibition was achieved by siRNA targeting of HIF-1α or via chetomin, a disruptor of interactions between HIF-1α and p300. The inhibition of the HIF-1 pathway was monitored by quantitative real-time PCR and Western blot analyses of the expression levels of HIF-1α and CA9. CA9 expression was investigated as a potential indicator of the efficacy of HIF-1 inhibition and the resulting radiosensitivity of malignant glioma cell lines was determined by clonogenic assay after irradiation under normoxic (2-10 Gy) or hypoxic (2-15 Gy) conditions.

Results: Although siRNA and chetomin show distinct modes of action, both attenuated the hypoxia-induced radioresistance of malignant glioma cell lines U251MG (DMF10: 1.35 and 1.18) and U343MG (DMF10: 1.78 and 1.48). However, siRNA and chetomin showed diverse effects on radiosensitivity under normoxic conditions in U251MG (DMF10: 0.86 and 1.35) and U343MG (DMF10: 1.33 and 1.02) cells.

Conclusions: Results from this in vitro study suggest that inhibition of HIF-1α is a promising strategy to sensitize human malignant gliomas to radiotherapy and that CA9 could serve as an indicator of effective HIF-1-related radiosensitization.

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Effects of HIF-1α-siRNA or CTM on Clonogenic Survival in U251MG and U343MG Cells (Cytotoxicity). A (U251MG) and B (U343MG), Effects of treatment with the indicated siRNA (75 nM) on the plating efficiency of non-irradiated cells. C (U251MG) and D (U343MG), Effects of treatment with 75 nM CTM on the plating efficiency of non-irradiated cells.
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Figure 4: Effects of HIF-1α-siRNA or CTM on Clonogenic Survival in U251MG and U343MG Cells (Cytotoxicity). A (U251MG) and B (U343MG), Effects of treatment with the indicated siRNA (75 nM) on the plating efficiency of non-irradiated cells. C (U251MG) and D (U343MG), Effects of treatment with 75 nM CTM on the plating efficiency of non-irradiated cells.

Mentions: The clonogenic survival assay is a crucial endpoint read-out that we used to determine the fraction of cells surviving the treatment with the HIF-1α-siRNA or CTM (Figure 4) and the combined treatment of HIF-1α-siRNA or CTM and radiation (Figure 5).


HIF-1α inhibition by siRNA or chetomin in human malignant glioma cells: effects on hypoxic radioresistance and monitoring via CA9 expression.

Kessler J, Hahnel A, Wichmann H, Rot S, Kappler M, Bache M, Vordermark D - BMC Cancer (2010)

Effects of HIF-1α-siRNA or CTM on Clonogenic Survival in U251MG and U343MG Cells (Cytotoxicity). A (U251MG) and B (U343MG), Effects of treatment with the indicated siRNA (75 nM) on the plating efficiency of non-irradiated cells. C (U251MG) and D (U343MG), Effects of treatment with 75 nM CTM on the plating efficiency of non-irradiated cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2992520&req=5

Figure 4: Effects of HIF-1α-siRNA or CTM on Clonogenic Survival in U251MG and U343MG Cells (Cytotoxicity). A (U251MG) and B (U343MG), Effects of treatment with the indicated siRNA (75 nM) on the plating efficiency of non-irradiated cells. C (U251MG) and D (U343MG), Effects of treatment with 75 nM CTM on the plating efficiency of non-irradiated cells.
Mentions: The clonogenic survival assay is a crucial endpoint read-out that we used to determine the fraction of cells surviving the treatment with the HIF-1α-siRNA or CTM (Figure 4) and the combined treatment of HIF-1α-siRNA or CTM and radiation (Figure 5).

Bottom Line: In this study, we investigated the effects of the inhibition of HIF-1α on cell survival and radiosensitivity in U251MG and U343MG glioma cells, using two different strategies.However, siRNA and chetomin showed diverse effects on radiosensitivity under normoxic conditions in U251MG (DMF10: 0.86 and 1.35) and U343MG (DMF10: 1.33 and 1.02) cells.Results from this in vitro study suggest that inhibition of HIF-1α is a promising strategy to sensitize human malignant gliomas to radiotherapy and that CA9 could serve as an indicator of effective HIF-1-related radiosensitization.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Radiotherapy, Faculty of Medicine, Martin-Luther-University Halle-Wittenberg, Ernst-Grube-Straße 40, 06097 Halle, Saale, Germany. jacqueline.kessler@medizin.uni-halle.de

ABSTRACT

Background: Hypoxia induces activation of the HIF-1 pathway and is an essential characteristic of malignant gliomas. Hypoxia has been linked to tumor progression, therapy resistance and poor prognosis. However, little is known about the impact of HIF-1α inhibition on radioresistance of malignant glioma.

Methods: In this study, we investigated the effects of the inhibition of HIF-1α on cell survival and radiosensitivity in U251MG and U343MG glioma cells, using two different strategies. HIF-1α inhibition was achieved by siRNA targeting of HIF-1α or via chetomin, a disruptor of interactions between HIF-1α and p300. The inhibition of the HIF-1 pathway was monitored by quantitative real-time PCR and Western blot analyses of the expression levels of HIF-1α and CA9. CA9 expression was investigated as a potential indicator of the efficacy of HIF-1 inhibition and the resulting radiosensitivity of malignant glioma cell lines was determined by clonogenic assay after irradiation under normoxic (2-10 Gy) or hypoxic (2-15 Gy) conditions.

Results: Although siRNA and chetomin show distinct modes of action, both attenuated the hypoxia-induced radioresistance of malignant glioma cell lines U251MG (DMF10: 1.35 and 1.18) and U343MG (DMF10: 1.78 and 1.48). However, siRNA and chetomin showed diverse effects on radiosensitivity under normoxic conditions in U251MG (DMF10: 0.86 and 1.35) and U343MG (DMF10: 1.33 and 1.02) cells.

Conclusions: Results from this in vitro study suggest that inhibition of HIF-1α is a promising strategy to sensitize human malignant gliomas to radiotherapy and that CA9 could serve as an indicator of effective HIF-1-related radiosensitization.

Show MeSH
Related in: MedlinePlus