PC SPES (BotanicLab, Brea, California) an herbal supplement for patients with
prostate cancer, is composed of 7 highly concentrated Chinese herbs and 1 US herb. It was developed in seeking positive attributes of Chinese and Western medicine for
cancer treatment. Chemical standardization of this composition showed that
baicalin is the most abundant active compound. Several reports on phase 2 clinical studies of
PC SPES suggest that it is a well-tolerated active treatment for
androgen-independent
prostate cancer. In this report, data obtained from various laboratory experiments will be presented to elucidate the in vitro mechanism. Profound
biologic effects of
PC SPES on
prostate cancer cells were observed on both
androgen-dependent (LNCap) and
androgen-independent (DU-145) cell lines. These effects include the following: (1) induction of cell apoptosis and cell cycle modulation; (2) inhibition of cell proliferation; (3) downregulation of bcl-2, bcl-6,
proliferating cell nuclear antigen, and
prostate-specific antigen proteins; (4) downregulation of
androgen receptor (AR); and (5) upregulation of p53, bax, and p21
proteins. Concurrent animal studies using 2 different models, Copenhagen rats and nude mice, confirmed a dose-dependent suppressive effect of
PC SPES on
tumor volumes and
tumor progression. Our results show that the cytotoxic and
cytostatic properties of
PC SPES are not entirely dependent on the presence of AR. The antitumor mechanism of
PC SPES is complex. It involves multiple metabolic pathways, such that the whole extract acts on redundant mechanisms, which otherwise will permit cell survival if a single-target agent is used.