Figure 2.

SMYD3 Mediates DSB Repair in BC Cells

(A) High-SMYD3 MDA-MB-231 cells were transfected with control (siCTRL) or SMYD3-specific (siSMYD3) siRNAs, exposed to 0.8 nM neocarzinostatin (NCS) after 48 h, and fixed at the indicated time points. Upper panel: Number of 53BP1 foci/cell based on immunostaining for 53BP1. At least 100 cells were analyzed for each time point. Means and standard deviations obtained from at least three independent experiments are shown in the graph on the left. The graph in the middle shows the number of 53BP1 foci/cell before NCS addition (endogenous damage). The graph on the right shows the percentage of 53BP1 foci/cell induced by NCS and detectable 24 h after drug exposure (residual damage NCS 24h). Lower panel: double immunostaining for 53BP1 (red) and γH2AX (green). Nuclei were stained with DAPI (blue). Representative images are shown. The scale bar represents 5 μm.

(B) MDA-MB-231 cells were treated with 10 μM BCI-121 2.5 h before NCS addition. Immunostaining for 53BP1 and foci counting were performed and are graphically shown as in (A).

(C) Same as in (B) but cells were treated with 1 μM EPZ031686.

(D and E) Same as in (B), but experiments were performed on high-SMYD3 MCF7 cells (D) and low-SMYD3 MDA-MB-468 cells (E).

Data are presented as mean (SD), and significance was calculated using Student's t-test; ∗p < 0.05, ∗∗p < 0.01, and ∗∗∗p < 0.001. Results are representative of at least three independent experiments.

See also Figure S3.