Fig. 2

Estrogen induces DNA damage in both G1 and S phases of OvCa cells. a-b, Indicated cells were pre-treated with estrogen (E2, 50 nM) for 12 h. DSBs were detected by IF staining of 53BP1 (a) and γH2AX (b). Estrogen triggers elevation of endogenous DNA damage in OVCAR-8TR instead of A549 and L02 cells. c, Comparison of ER gene expression by semi-quantitative PCR in indicated cell lines. The images were cropped and full-length gels are presented in Supplementary Figure 1. d, Parallel quantification of 53BP1 foci in OVCAR-8TR cells pre-treated with estrogen (E2) or tamoxifen (TAM, 50 nM) for 3 h. There was no DSB induction by TAM. e, Quantification of 53BP1 foci in cyclin A-positive (G1) and negative (non-G1) cells, respectively. f-g, Enumeration of E2-induced 53BP1 foci in OVCAR-8TR cells pre-treated with serum starvation for 24 h (f) or hydroxyurea (g) for 2 h (g). Statistic analysis in this Figure: p values were calculated by unpaired t-test between two groups in 3 biological repeats; NS: non-significant