Effect of androgen on activation of ATM/ATR DNA damage checkpoint in LNCaP cells.

<p>(A) Levels of phosphor-ATM (Ser 1981), phosphor-ATR (Ser 428), phosphor-Chk2 (Thr 68), phosphor-Chk1 (Ser317) and γH2AX in LNCaP cells after 24 hrs of R1881 treatment. (B) Androgen induces G1 arrest in LNCaP cells. LNCaP cells supplemented with R1881 alone (upper panel) or together with nocodazole (lower panel) for 24 hours were harvested and fixed for cell cycle analysis using flow cytometry. The percentages represent cell population at different phases of the cell cycle. (C) Protein expression of ATM and ATR in LNCaP-shCon, shATM and shATR transfectants were examined by Western blotting. (D) Androgen fails to induce G1 arrest in shATM transfectants. shCon, shATM and shATR transfectants were treated with different doses of R1881 for 24 hours and cells were fixed for flow cytometry analysis. Table showed the percentage change of G1 phase and S phase LNCaP cells after supplemented with 1 nM R1881 for 24 hours. Androgen fails to suppress cell proliferation in shATM LNcaP transfectant.