Acta Med. 2012, 55: 66-73

Radio-Sensitization of Human Leukaemic MOLT-4 Cells by DNA-Dependent Protein Kinase Inhibitor, NU7026

Aleš Tichýa,b, Eva Novotnáb, Kamila Ďurišováb, Barbora Šalovskáa,b, Radka Sedlaříkováb, Jaroslav Pejchalc, Lenka Zárybnickáb, Jiřina Vávrováb, Zuzana Šinkorováb, Martina Řezáčováa

aCharles University in Prague, Faculty of Medicine in Hradec Králové, Czech Republic: Institute of Medical Biochemistry
bUniversity of Defence in Brno, Faculty of Health Sciences in Hradec Králové, Czech Republic: Department of Radiobiology
cUniversity of Defence in Brno, Faculty of Health Sciences in Hradec Králové, Czech Republic: Centrum of Advanced Studies

Received October 26, 2011
Accepted May 9, 2012

In this paper we describe the influence of NU7026, a specific inhibitor of DNA-dependent protein kinase, phosphoinositide 3-kinase, and ATM-kinase on molecular and cellular mechanisms triggered by ionising irradiation in human T-lymphocyte leukaemic MOLT-4 cells. We studied the effect of this inhibitor (10 μM) combined with gammaradiation (1 Gy) leading to DNA damage response and induction of apoptosis. We used methods for apoptosis assessment (cell viability count and flow-cytometric analysis) and cell cycle analysis (DNA content measurement) and we detected expression and post-translational modifications (Western blotting) of proteins involved in DNA repair signalling pathways. Pre-treatment with NU7026 resulted into decreased activation of checkpoint kinase-2 (Thr68), p53 (Ser15 and Ser392), and histone H2A.X (Ser139) 2 hours after irradiation. Subsequently, combination of radiation and inhibitor led to decreased amount of cells in G2-phase arrest and into increased apoptosis after 72 hours. Our results indicate that in leukaemic cells the pre-incubation with inhibitor NU7026 followed by low doses of ionising radiation results in radio-sensitising of MOLT-4 cells via diminished DNA repair and delayed but pronounced apoptosis. This novel approach might offer new strategies in combined treatment of leukaemia diseases.


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