Journal
MOLECULAR CANCER THERAPEUTICS
Volume 7, Issue 7, Pages 1772-1781Publisher
AMER ASSOC CANCER RESEARCH
DOI: 10.1158/1535-7163.MCT-07-2200
Keywords
-
Categories
Ask authors/readers for more resources
We have already reported that epidermal growth factor receptor/phosphaticlylinositol 3-kinase/AKT signaling is an important pathway in regulating radiation sensitivity and DNA double-strand break (DNA-dsb) repair of human tumor cells. In the present study, we investigated the effect of AKT1 on DNA-dependent protein kinase catalytic subunit (DNA-PKcs) activity and DNA-dsb repair in irradiated non-small cell lung cancer cell lines A549 and H460. Treatment of cells with the specific AKT pathway inhibitor API-59CJ-OH (API; 1-5 mu mol/L) reduced clonogenic survival between 40% and 85% and enhanced radiation sensitivity of both cell lines significantly. As indicated by fluorescence-activated cell sorting analysis (sub-G, cells) and poly(ADP-ribose) polymerase cleavage, API treatment or transfection with AKT1-small interfering RNA (siRNA) induced apoptosis of H460 but not of A549 cells. However, in either apoptosis-resistant A549 or apoptosis-sensitive H460 cells, API and/or AKT1-siRNA did not enhance poly(ADP-ribose) polymerase cleavage and apoptosis following irradiation. Pretreatment of cells with API or transfection with AKT1-siRNA strongly inhibited radiation-induced phosphorylation of DNA-PKcs at T2609 and S2056 as well as repair of DNA-dsb as measured by the gamma-H2AX foci assay. Coimmunoprecipitation experiments showed a complex formation of activated AKT and DNA-PKcs, supporting the assumption that AKT plays an important regulatory role in the activation of DNA-PKcs in irradiated cells. Thus, targeting of AKT enhances radiation sensitivity of lung cancer cell lines A549 and H460 most likely through specific inhibition of DNA-PKcs-dependent DNA-dsb repair but not through enhancement of radiation-induced apoptosis.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available