Objectives. To investigate the antitumor effects of Scutellariae radix and its components baicalein, baicalin, and wogonin on human bladder cancer cell lines (KU-1 and EJ-1) and a murine bladder cancer cell line (MBT-2).

Methods. Bladder cancer cells were incubated with various concentrations of the agents. Antiproliferative activity against the bladder cancer cell lines was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diplenyl tetrazolium bromide assay. In an in vivo experiment, the mice were subcutaneously injected with MBT-2 cells, and Scutellariae radix was orally administered at a dose of 2 or 10 mg per mouse one time daily for 10 days from day 11 to day 20.

Results. All the drugs inhibited cell proliferation in a dose-dependent manner, but baicalin exhibited the greatest antiproliferative activity. The concentration of baicalin necessary to obtain 50% inhibition was 3.4 μg/mL for KU-1, 4.4 μg/mL for EJ-1, and 0.93 μg/mL for MBT-2. For KU-1 and MBT-2, the percentage of cell survival significantly decreased (P <0.05) at a baicalin concentration of 1 μg/mL. In an in vivo experiment, antitumor effects of Scutellariae radix on C3H/HeN mice implanted with MBT-2 were investigated. All the control mice showed a progressive increase in tumor volume, reaching 2.81 ± 0.18 cm³ on day 20 and 5.36 ± 0.44 cm³ on day 25. However, when Scutellariae radix was orally administered at a dose of 10 mg per mouse one time daily for 10 days from day 11 to day 20, the tumor volume was 1.99 ± 0.19 cm³ on day 20 and 3.86 ± 0.26 cm³ on day 25, a significant inhibition of tumor growth (P <0.05).

Conclusions. These results suggest that Chinese herbal medicines may become an attractive and promising treatment for bladder cancer.