Telomere damage induced by the G-quadruplex ligand RHPS4 has an antitumor effect
J. Clin. Invest. Erica Salvati, et al. 117:3236 doi:10.1172/JCI32461 [
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Figure 3RHPS4-induced DNA damage at the telomeres depends on ATR kinase. Human transformed BJ-EHLT cells exposed to the PI3K inhibitor caffeine or transfected with
siATM or
siATR SMARTpool or
siGFP (as control) and treated with RHPS4 were fixed and processed for immunofluorescence using antibodies against γ-H2AX and TRF1. (
A) TIF index was calculated as the percentage of TIF-positive cells under the indicated conditions. Cells with 4 or more γ-H2AX foci were scored as TIF positive (
n = 72). The mean of 3 independent experiments is reported. Error bars indicate SD. (
B) Western blot analysis of ATR and ATM protein expression in
siGFP and
siATR- or
siATM-transfected cells. (
C) Representative confocal images of merged TRF1 (green) and γ-H2AX (red) staining of the indicated samples. Original magnification, ×63.
