Fig. 1.

Arsenic trioxide inhibits bladder cancer cell and tumor growth and downregulates Sp1, Sp3 and Sp4. [A] Inhibition of cell growth and Sp downregulation. Cells were treated with arsenic trioxide for 24 hr and cell growth and Sp proteins were determined as outlined in the Materials and Methods. [B] Prolonged treatment of KU7 cells. Cells were treated with 0.75 or 1.0 μM arsenic trioxide for 120 or 144 hr and cell proliferation and expression of Sp1, Sp3 and Sp4 proteins were determined by cell counting and western blots as described in the Materials and Methods. High and low molecular weight forms of Sp3 protein were detected as previously described in other cancer cell lines [28,34–37,39,40]. [C] Arsenic trioxide inhibits bladder tumor growth and downregulates Sp proteins. Athymic nude mice were treated with PBS/KOH (solvent control) or arsenic trioxide (5 mg/kg/day) in PBS/KOH for 24 days. Tumor volumes were determined every second day and tumor weights were determined at sacrifice as described in the Materials and Methods. Expression of Sp proteins was determined in triplicate (3 animals/group) by western blot analysis of tumor lysates as described in the Materials and Methods, and significant (p < 0.05) decreases in Sp1, Sp3 and Sp4 proteins were observed in the arsenic trioxide-treated tumors.