Severe hypoxia increases expression of ATM and DNA-PKcs and it increases their activities through Src and AMPK signaling pathways.
Biochem Biophys Res Commun
; 505(1): 13-19, 2018 10 20.
Article
en En
| MEDLINE
| ID: mdl-30224064
ABSTRACT
BACKGROUND:
Solid tumors often contain hypoxic regions because an abnormal and inefficient tumor vasculature is unable to supply sufficient oxygen. Tissue hypoxia is generally defined as a low oxygen concentration of less than 2%. It is well known that tumor cells under severe hypoxia, where oxygen concentration is less than 0.1%, show radioresistance. It has been reported that cells under severe hypoxia show different responses from those under mild hypoxia, where oxygen concentration is 0.5-2.0%. In the present study, we investigated the effects of severe hypoxia on expression and activities of ATM and DNA-dependent protein kinase catalytic subunit (DNA-PKcs), both of which regulate DNA double-strand breaks (DSBs) repair and radiation sensitivity. Signaling pathways for increasing expression and activities of ATM and DNA-PKcs under severe hypoxia were also investigated.METHODS:
SV40-transformed human fibroblast cell lines, LM217 and LM205, and normal human dermal fibroblasts (NHDF) were used. Cells were cultured at an oxygen concentration of less than 0.05% for 12 or 24â¯h. Activities and/or expression of ATM, DNA-PKcs, Src, Caveolin-1, EGFR, HIF-1α, PDK1, Akt, AMPKα, and mTOR were estimated by Western blot analyses.RESULTS:
Severe hypoxia increased expression and activities of ATM, DNA-PKcs, Src, Caveolin-1, EGFR, PDK1, Akt, and AMPKα, and decreased expression and activity of mTOR. A specific Src inhibitor, PP2 suppressed activation of ATM, DNA-PKcs, Caveolin-1, EGFR, and Akt under severe hypoxia. Treatment with siRNA for AMPKα suppressed activation of ATM and DNA-PKcs and increase of ATM expression under severe hypoxia.CONCLUSION:
Our data show that severe hypoxia increases activities of ATM and DNA-PKcs through Src and AMPK signaling pathways, and that activation of AMPK under hypoxia causes increase of ATM expression. Since ATM and DNA-PKcs play important roles in DSBs repair induced by ionizing radiation, those data provide novel insights on the molecular mechanism of the cellular radioresistance under severe hypoxia.Palabras clave
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Proteínas Nucleares
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Transducción de Señal
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Familia-src Quinasas
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Proteína Quinasa Activada por ADN
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Proteínas Quinasas Activadas por AMP
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Proteínas de la Ataxia Telangiectasia Mutada
Límite:
Humans
Idioma:
En
Revista:
Biochem Biophys Res Commun
Año:
2018
Tipo del documento:
Article
País de afiliación:
Japón