XAV939 impairs the clonogenic and proliferative capacity and enhances MB cells radio-sensitivity.

<p><b>A.</b><i>Growth curves assay</i>. XAV939 (5 μM) treated cells and IR (2 Gy) treated cells showed a similar growth rate with about 40% (DAOY) and 30% (ONS-76) reductions compared to DMSO control cells (<i>p</i> <. 01). In both cell lines, the co-administration of XAV939 and IR induces a massive cell proliferation inhibition with a decrease of about 70% (<i>p</i> <. 001). Each point represents the mean ± s.e. of three independent assays. <b>B.</b><i>Clonogenic forming assay</i>. XAV939 alone (5 μM) inhibits a clone-forming ability in both MB cell lines as well as IR treatment (2 Gy), with a clonogenic capability reduction of about 38% (<i>p</i> <. 01). The IR and drug co-administration induces a drastic inhibition of clone-forming in both cell lines (70% reduction in DAOY cells and 81% in ONS-76 compared with control cells, <i>p</i> <. 001).</p

XAV939 affects the DNA repair efficacy of MB cell lines.

<p>Neutral Comet Assay was performed on IR treated cells (10 Gy), with or without XAV939 administration, at different time points post radiations (0, 16, and 24 h). Histograms represent mean ± s.e. of TM measured in at least three independent experiments for each treatment and time point. The greatest TM was observed immediately after IR treatment in both cell lines (A: DAOY, B: ONS-76). XAV939 induces enhanced TM values at 16 h and 24 h after IR compared to DMSO irradiated cells indicating a minor DNA repair capacity. On the right of the figure, a representative example of comets for each treatment obtained in DAOY (upper) and ONS-76 (down) cells.</p

XAV939 inhibits TNKS PARP-activity in MB cell lines.

<p>WB analysis and densitometry of total and nuclear MB cells extracts after XAV939 treatment: MB cell lines (DAOY, ONS-76) were treated with 5 μM XAV939 or with an equal volume of DMSO. <b>A.</b> Both cell lines showed an increase in total Axin protein levels at 8 h after treatment (80% and 70% respectively in ONS-76 and DAOY compared to DMSO treated control, <i>p</i> <. 05), followed by a β-catenin decrease in total (30%, <i>p</i> <. 05) and, in particular, in nuclear extracts, at 16 h after drug administration (80% reduction compared with control, <i>p</i> <. 001). <b>B.</b> XAV939 induced a DNA-PKcs protein level reduction of about 40% at 8 h and 16 h after treatment compared to non-treated control cells (<i>p</i> <. 05 in A, <i>p</i> <. 01 in B). Densitometry data (mean ± s.e.) were normalized with β-actin (for total extracts) and lamin-b (for nuclear extracts) and are representative of the results derived from three independent experiments.</p