Figure 1.
The induction of PIAS1 and Smad2 expression and the formation of PIAS1/Smad2/4 complex induced by zinc. (a) Zinc promoted cell apoptosis of either androgen-dependent LNCaP or androgen-independent PC3 prostate cancer cells. LNCaP and PC3 cells were treated with indicated concentrations of ZnSO4 for 24 h. Sub-G1 populations were detected using flow cytometry. Columns, mean (n=3); bars, S.D.; ***P<0.001 (one-way ANOVA). (b) Zinc selectively increased Smad2 and PIAS1 expression. LNCaP cells were treated with 150 μM ZnSO4 for indicated periods (0, 4, 8, 12 and 24 h). Immunoblot analyses were performed with antibodies of Smad3, Smad2, Smad4 or β-actin and PIAS1, PIAS2 and (c) PIAS3 or β-actin. (d and e) The immunoprecipitation experiments with anti-Smad4 or anti-PIAS1 were carried out in LNCaP cells with or without 150 μM zinc treatment and then analyzed by immunoblot analysis using the indicated antibodies against Smad4, Smad3, Smad2, phosphorylated Smad2, PIAS1, PIAS2, or PIAS3 (d), or against PIAS1, Smad4, or Smad2/3 (e)