Wortmannin, a specific inhibitor of phosphatidylinositol-3-kinase, induces accumulation of DNA double-strand breaks.

Wortmannin, a fungal metabolite, is a specific inhibitor of the phosphatidylinositol 3-kinase (PI3K) family, which includes double-stranded DNA dependent protein kinase (DNA-PK) and ataxia telangiectasia mutated kinase (ATM). We investigated the effects of wortmannin on DNA damage in DNA-PK-deficient cells obtained from severe combined immunodeficient mice (SCID cells). Survival of wortmannin-treated cells decreased in a concentration-dependent manner. After treatment with 50 μM wortmannin, survival decreased to 60% of that of untreated cells. We observed that treatment with 20 and 50 μM wortmannin induced DNA damage equivalent to that by 0.37 and 0.69 Gy, respectively, of γ-ray radiation. The accumulation of DNA double-strand breaks (DSBs) in wortmannin-treated SCID cells was assessed using pulsed-field gel electrophoresis. The maximal accumulation was observed 4 h after treatment. Moreover, the presence of DSBs was confirmed by the ability of nuclear extracts from γ-ray-irradiated SCID cells to produce in vitro phosphorylation of histone H2AX. These results suggest that wortmannin induces cellular toxicity by accumulation of spontaneous DSBs through inhibition of ATM. © The Author(s) 2020. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.

Citation

Makoto Ihara, Kazuko Shichijo, Satoshi Takeshita, Takashi Kudo. Wortmannin, a specific inhibitor of phosphatidylinositol-3-kinase, induces accumulation of DNA double-strand breaks. Journal of radiation research. 2020 Mar 23;61(2):171-176

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PMID: 32052028

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