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DNA-PK inhibition by NU7441 sensitizes breast cancer cells to ionizing radiation and doxorubicin

Lookup NU author(s): Wojciech Ciszewski, Dr Michele Tavecchio, Professor Nicola CurtinORCiD

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Abstract

DNA-dependent protein kinase (DNA-PK) plays a key role in the repair of DNA double-strand breaks (DSBs) that are probably the most deleterious form of DNA damage. Inhibition of DNA-PK has been considered as an attractive approach to decrease resistance to therapeutically induced DNA DSBs. Ionizing radiation (IR) and doxorubicin, which induce DSBs, are used in the treatment of breast cancer. We determined the cellular concentration of DNA-PK and other DSB-activated kinases: ATM and ATR and the effect of DNA-PK inhibition by NU7441 on DNA repair, cell cycle, and survival after IR or doxorubicin treatment in three human breast cancer cell lines (MCF-7, MDA-MB-231, and T47D) representing different breast cancer subtypes. T47D cells had the highest expression of DNA-PKcs, ATM, and ATR and the most rapid rate of DNA DSB repair. IR caused a 10- to 16-fold increase in DNA-PK activity and two to threefold induction of ATM in all 3 cell lines. NU7441 inhibited IR-induced DNA-PK activity in all cell lines with IC(50)s in the range 0.17-0.25 mu M. NU7441 retarded the repair of DSB and significantly increased the sensitivity of all cell lines to IR (4- to 12-fold) and doxorubicin (3- to 13-fold). The greatest sensitiziation by NU7441 was observed in MDA-MB-231 cells. NU7441 affected the cell cycle distribution in all studied cell lines; increasing accumulation of cells in G2/M phase after DNA damage. Our data indicate that DNA-PK might be an effective target for chemo- and radio-potentiation in breast cancer and suggest that further development of DNA-PK inhibitors for clinical use is warranted.

Publication metadata

Author(s): Ciszewski WM, Tavecchio M, Dastych J, Curtin NJ

Publication type: Article

Publication status: Published

Journal: Breast Cancer Research and Treatment

Year: 2014

Volume: 143

Issue: 1

Pages: 47-55

Print publication date: 29/11/2013

ISSN (print): 0167-6806

ISSN (electronic): 1573-7217

Publisher: Springer

URL: http://dx.doi.org/10.1007/s10549-013-2785-6

DOI: 10.1007/s10549-013-2785-6

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