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Int. J. Mol. Sci. 2017, 18(11), 2473; https://doi.org/10.3390/ijms18112473

Akt1 Stimulates Homologous Recombination Repair of DNA Double-Strand Breaks in a Rad51-Dependent Manner

1
Division of Radiobiology and Molecular Environmental Research, Department of Radiation Oncology, University of Tuebingen, 72076 Tuebingen, Germany
2
German Cancer Consortium (DKTK), Partner site Tuebingen, and German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
*
Authors to whom correspondence should be addressed.
Received: 10 October 2017 / Revised: 3 November 2017 / Accepted: 3 November 2017 / Published: 20 November 2017
(This article belongs to the Section Molecular Pathology, Diagnostics, and Therapeutics)
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Abstract

Akt1 is known to promote non-homologous end-joining (NHEJ)-mediated DNA double-strand break (DSB) repair by stimulation of DNA-PKcs. In the present study, we investigated the effect of Akt1 on homologous recombination (HR)-dependent repair of radiation-induced DSBs in non-small cell lung cancer (NSCLC) cells A549 and H460. Akt1-knockdown (Akt1-KD) significantly reduced Rad51 protein level, Rad51 foci formation and its colocalization with γH2AX foci after irradiation. Moreover, Akt1-KD decreased clonogenicity after treatment with Mitomycin C and HR repair, as tested by an HR-reporter assay. Double knockdown of Akt1 and Rad51 did not lead to a further decrease in HR compared to the single knockdown of Rad51. Consequently, Akt1-KD significantly increased the number of residual DSBs after irradiation partially independent of the kinase activity of DNA-PKcs. Likewise, the number of residual BRCA1 foci, indicating unsuccessful HR events, also significantly increased in the irradiated cells after Akt1-KD. Together, the results of the study indicate that Akt1 seems to be a regulatory component in the HR repair of DSBs in a Rad51-dependent manner. Thus, based on this novel role of Akt1 in HR and the previously described role of Akt1 in NHEJ, we propose that targeting Akt1 could be an effective approach to selectively improve the killing of tumor cells by DSB-inducing cytotoxic agents, such as ionizing radiation. View Full-Text
Keywords: homologous recombination; Akt1; Rad51; DNA double-strand break repair; non-small cell lung cancer homologous recombination; Akt1; Rad51; DNA double-strand break repair; non-small cell lung cancer
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Mueck, K.; Rebholz, S.; Harati, M.D.; Rodemann, H.P.; Toulany, M. Akt1 Stimulates Homologous Recombination Repair of DNA Double-Strand Breaks in a Rad51-Dependent Manner. Int. J. Mol. Sci. 2017, 18, 2473.

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