Hypoxia-inducible transcription factor-1α promotes hypoxia-induced A549 apoptosis via a mechanism that involves the glycolysis pathway
<p>Abstract</p> <p>Background</p> <p>Hypoxia-inducible transcription factor-1α (HIF-1α), which plays an important role in controlling the hypoxia-induced glycolysis pathway, is a "master" gene in the tissue hypoxia response during tumor development. However, i...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
BMC
2006-01-01
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| Series: | BMC Cancer |
| Online Access: | http://www.biomedcentral.com/1471-2407/6/26 |
| _version_ | 1811315047747551232 |
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| author | Cao GuiQun Li ShuangQing Yan NaiHong Liu XiaoJing Luo FengMing Cheng QingYing Xia QingJie Wang HongJing |
| author_facet | Cao GuiQun Li ShuangQing Yan NaiHong Liu XiaoJing Luo FengMing Cheng QingYing Xia QingJie Wang HongJing |
| author_sort | Cao GuiQun |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Hypoxia-inducible transcription factor-1α (HIF-1α), which plays an important role in controlling the hypoxia-induced glycolysis pathway, is a "master" gene in the tissue hypoxia response during tumor development. However, its role in the apoptosis of non-small cell lung cancer remains unknown. Here, we have studied the effects of HIF-1α on apoptosis by modulating HIF-1α gene expression in A549 cells through both siRNA knock-down and over-expression.</p> <p>Methods</p> <p>A549 cells were transfected with a HIF-1α siRNA plasmid or a HIF-1α expression vector. Transfected cells were exposed to a normoxic or hypoxic environment in the presence or absence of 25 mM HEPES and 2-deoxyglucose (2-DG) (5 mM). The expression of three key genes of the glycolysis pathway, glucose transporter type 1(GLUT1), phosphoglycerate kinase 1(PGK1), and hexokinase 1(HK1), were measured using real-time RT-PCR. Glycolysis was monitored by measuring changes of pH and lactate concentration in the culture medium. Apoptosis was detected by TUNEL assay and flow cytometry.</p> <p>Results</p> <p>Knocking down expression of HIF-1α inhibited the glycolysis pathway, increased the pH of the culture medium, and protected the cells from hypoxia-induced apoptosis. In contrast, over-expression of HIF-1α accelerated glycolysis in A549 cells, decreased the pH of the culture medium, and enhanced hypoxia-induced apoptosis. These effects of HIF-1α on glycolysis, pH of the medium, and apoptosis were reversed by treatment with the glycolytic inhibitor, 2-DG. Apoptosis induced by HIF-1α over-expression was partially inhibited by increasing the buffering capacity of the culture medium by adding HEPES.</p> <p>Conclusion</p> <p>During hypoxia in A549 cells, HIF-1α promotes activity of the glycolysis pathway and decreases the pH of the culture medium, resulting in increased cellular apoptosis.</p> |
| first_indexed | 2024-04-13T11:23:17Z |
| format | Article |
| id | doaj.art-8d9284c1c2e749ceacd43a87218cbd5a |
| institution | Directory Open Access Journal |
| issn | 1471-2407 |
| language | English |
| last_indexed | 2024-04-13T11:23:17Z |
| publishDate | 2006-01-01 |
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| series | BMC Cancer |
| spelling | doaj.art-8d9284c1c2e749ceacd43a87218cbd5a2022-12-22T02:48:46ZengBMCBMC Cancer1471-24072006-01-01612610.1186/1471-2407-6-26Hypoxia-inducible transcription factor-1α promotes hypoxia-induced A549 apoptosis via a mechanism that involves the glycolysis pathwayCao GuiQunLi ShuangQingYan NaiHongLiu XiaoJingLuo FengMingCheng QingYingXia QingJieWang HongJing<p>Abstract</p> <p>Background</p> <p>Hypoxia-inducible transcription factor-1α (HIF-1α), which plays an important role in controlling the hypoxia-induced glycolysis pathway, is a "master" gene in the tissue hypoxia response during tumor development. However, its role in the apoptosis of non-small cell lung cancer remains unknown. Here, we have studied the effects of HIF-1α on apoptosis by modulating HIF-1α gene expression in A549 cells through both siRNA knock-down and over-expression.</p> <p>Methods</p> <p>A549 cells were transfected with a HIF-1α siRNA plasmid or a HIF-1α expression vector. Transfected cells were exposed to a normoxic or hypoxic environment in the presence or absence of 25 mM HEPES and 2-deoxyglucose (2-DG) (5 mM). The expression of three key genes of the glycolysis pathway, glucose transporter type 1(GLUT1), phosphoglycerate kinase 1(PGK1), and hexokinase 1(HK1), were measured using real-time RT-PCR. Glycolysis was monitored by measuring changes of pH and lactate concentration in the culture medium. Apoptosis was detected by TUNEL assay and flow cytometry.</p> <p>Results</p> <p>Knocking down expression of HIF-1α inhibited the glycolysis pathway, increased the pH of the culture medium, and protected the cells from hypoxia-induced apoptosis. In contrast, over-expression of HIF-1α accelerated glycolysis in A549 cells, decreased the pH of the culture medium, and enhanced hypoxia-induced apoptosis. These effects of HIF-1α on glycolysis, pH of the medium, and apoptosis were reversed by treatment with the glycolytic inhibitor, 2-DG. Apoptosis induced by HIF-1α over-expression was partially inhibited by increasing the buffering capacity of the culture medium by adding HEPES.</p> <p>Conclusion</p> <p>During hypoxia in A549 cells, HIF-1α promotes activity of the glycolysis pathway and decreases the pH of the culture medium, resulting in increased cellular apoptosis.</p>http://www.biomedcentral.com/1471-2407/6/26 |
| spellingShingle | Cao GuiQun Li ShuangQing Yan NaiHong Liu XiaoJing Luo FengMing Cheng QingYing Xia QingJie Wang HongJing Hypoxia-inducible transcription factor-1α promotes hypoxia-induced A549 apoptosis via a mechanism that involves the glycolysis pathway BMC Cancer |
| title | Hypoxia-inducible transcription factor-1α promotes hypoxia-induced A549 apoptosis via a mechanism that involves the glycolysis pathway |
| title_full | Hypoxia-inducible transcription factor-1α promotes hypoxia-induced A549 apoptosis via a mechanism that involves the glycolysis pathway |
| title_fullStr | Hypoxia-inducible transcription factor-1α promotes hypoxia-induced A549 apoptosis via a mechanism that involves the glycolysis pathway |
| title_full_unstemmed | Hypoxia-inducible transcription factor-1α promotes hypoxia-induced A549 apoptosis via a mechanism that involves the glycolysis pathway |
| title_short | Hypoxia-inducible transcription factor-1α promotes hypoxia-induced A549 apoptosis via a mechanism that involves the glycolysis pathway |
| title_sort | hypoxia inducible transcription factor 1α promotes hypoxia induced a549 apoptosis via a mechanism that involves the glycolysis pathway |
| url | http://www.biomedcentral.com/1471-2407/6/26 |
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