PKB/Akt promotes DSB repair in cancer cells through upregulating Mre11 expression following ionizing radiation
Autor: | Wen Jun Zhou, Dan Dan Li, Jun Tang, Yi Xin Zeng, Guo Kai Feng, Jun Ma, Shu-Na Chen, R. Deng, Xiao Feng Zhu, Liang Ping Xia |
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Rok vydání: | 2010 |
Předmět: |
Cancer Research
Small interfering RNA animal structures DNA Repair Lymphoid Enhancer-Binding Factor 1 Gene Expression Biology Transfection medicine.disease_cause Radiation Tolerance Glycogen Synthase Kinase 3 Neoplasms Radiation Ionizing Genetics medicine Humans DNA Breaks Double-Stranded Molecular Biology Protein kinase B beta Catenin PI3K/AKT/mTOR pathway Oligonucleotide Array Sequence Analysis MRE11 Homologue Protein Gene knockdown Glycogen Synthase Kinase 3 beta fungi Molecular biology DNA-Binding Proteins Enzyme Activation Gene Expression Regulation Neoplastic enzymes and coenzymes (carbohydrates) Cell culture Gene Knockdown Techniques embryonic structures Cancer cell Carcinogenesis Proto-Oncogene Proteins c-akt HeLa Cells Signal Transduction |
Zdroj: | Oncogene. 30:944-955 |
ISSN: | 1476-5594 0950-9232 |
Popis: | An elevated DNA-repair capacity in cancer cells leads to radiation resistance and severely limits the efficacy of radiation therapy. Activation of Akt is tightly associated with resistance to radiotherapy, and Mre11 protein has important role during the repair of DNA double-strand breaks (DSBs). In this report, our results showed that inhibition of Akt activity impaired the repair of DSBs in CNE2 cells, whereas activated Akt promoted the repair of DSBs in HeLa cells. Knockdown of Mre11 also impaired the process of DSB repair in both these two cell lines. More importantly, we found that Akt could regulate Mre11 expression. Inhibition of Akt activity by small interfering RNA or LY294002 efficiently downregulated the Mre11 expression in CNE2 cells, and transfection with myr-Akt plasmid in HeLa cells upregulated the Mre11 expression. In addition, luciferase reporter analysis revealed that Mre11 reporter activity increased after transfection with myr-Akt1 plasmids, and this myr-Akt1-induced transcriptional activity was blocked in the presence of LY294002. Further study showed GSK3β/β-catenin/LEF-1 pathway was involved in this regulation. Knockdown of β-catenin or LEF-1 led to the downregulation of Mre11, whereas overexpression of β-catenin led to upregulation of Mre11. The chromatin immunoprecipitation assay assay showed β-catenin/LEF-1 heterodimer could directly bind to the promoter of Mre11 in vivo. And the luciferase activity of the pGL3-Mre11 and pGL3-Lef increased in HeLa cells following β-catenin plasmid co-transfected, but was abolished when the LEF-1-binding conserved sequences of Mre11 promoter were mutated. These results together support Akt can upregulate the expression of Mre11 through GSK3β/ β-catenin/LEF pathway to elevate DSB-repair capacity in cancer cells. |
Databáze: | OpenAIRE |
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