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Fig. 4 | Journal of Experimental & Clinical Cancer Research

Fig. 4

From: Fisetin induces DNA double-strand break and interferes with the repair of radiation-induced damage to radiosensitize triple negative breast cancer cells

Fig. 4

Fisetin inhibits the repair of IR-induced DSB, which leads to chromosomal aberration in TNBC cells. A, B The cells were treated with the indicated concentrations of fisetin for 24 h and irradiated with 4 Gy. Twenty-four hours after irradiation γH2AX foci assay was performed as described in the Methods section. A The representative immunofluorescent images of γH2AX foci used for analyses. B Asterisks indicate significant inhibition of DSB repair shown by increased mean residual γH2AX ± SD after fisetin treatment compared to DMSO treated/ 4 Gy irradiated control (Ctrl) condition in 500 nuclei in MDA-MB-231 cells, 700 nuclei in MDA-MB-453 cells, 600 nuclei in MDA-MB-468 cells, 500 nuclei in HS 578T cells and 440 nuclei in HSF-7 cells, from 3 independent experiments. C MDA-MB-231 were transfected with 50 nM indicated siRNA and protein samples were isolated 72 h after transfection to analyze knockdown efficiency by Western blotting. In the parallel cultures, 24 h after transfection cells were treated with DMSO or fisetin (75 µM) for additional 24 h and irradiated with 4 Gy. γH2AX was performed 24 h after irradiation (72 h after transfection) and counted using FoCo software. The asterisks indicate significant difference in mean γH2AX ± SD between the indicated conditions (*p < 0.05, **p < 0.01, ***p < 0.001), ****p < 0.0001; students t-test) analyzed in 444 cells, from 3 independent experiments. The DMSO concentration in the cells treated with different concentrations of fisetin was kept similar. D The mean number of chromosomal aberrations analyzed in at least 50 metaphases 48 h after irradiation (2 Gy) or 72 h after treatment with fisetin (75 µM). (*p < 0.05, Mann–Whitney U test): n.s. = non-significant. Chr.: Chromosome

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