A phthalimidoalkanamide derived novel DNMT inhibitor enhanced radiosensitivity of A549 cells by inhibition of homologous recombination of DNA damage
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Purpose To elucidate the radiosensitizing effect and underlying mechanism of a new kind of DNA methyltransferase (DNMT) inhibitor with biological availability. Methods A novel non-nucleoside compound, designated as MA-17, was recently derived from a phthalimido alkanamide structure. DNMT expressions were confirmed in cultured human lung cancer (A549) and normal astrocyte (NHA) cells, radiosensitivity was measured using clonogenic assay, and assays of cell cycle alteration, apoptosis, DNA damage repair, and differential gene expression were undertaken. Results MA-17 significantly radiosensitized A549 cells with a mean dose enhancement ratio (DER) of 1.43 at the surviving fraction of 0.2 (p < 0.05 by one-tailed ratio paired t-test). MA-17 did not affect normal astrocytes (mean DER0.2, 1.016; p = 0.420). MA-17 demonstrated a mean half-life of 1.0 h in vivo and a relatively even distribution in various tissues. Pretreatment with MA-17 increased sub-G1 fractions and inhibited the repair of DNA double-strand breaks, which are induced by irradiation. We found that MA-17 also down-regulated DNA homologous recombination and the Fanconi anemia pathway (FANCA, BRCA1, and RAD51C) in A549 cells. This bioinformatics finding was confirmed in validation Western blot to evaluate the expression of vital proteins. Conclusions A novel phthalimido alkanamide derivative, a DNMT inhibitor, possessed both biostability and favorable and substantial radiosensitizing effects by augmenting apoptosis or inhibiting DNA damage repair.
KeywordsRadiosensitization DNMT inhibitor Epigenetics Cancer
We’d like to thank Ms. Soo Yeon Seo, for her precise in vitro work.
This research was supported by grant no 04–2016-0620, 04–2016-0830, 05–2016-0010 and 03–2017-0080 from the SNUH Research Fund and NRF-2013M2A2A7043683, NRF-2015M2B2A9029247. The funding source had no role in the design of this study, in data collection and interpretation, in the decision to publish, or in writing the manuscript.
Compliance with ethical standards
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. This article does not contain any studies with human participants performed by any of the authors.
Conflict of interest
The authors declare that they have no conflict of interest.
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