Induction of apoptosis and down-regulation of bcl-6 in Mutu I cells treated with ethanolic extracts of the Chinese herbal supplement PC-SPES

PC-SPES, an HPLC-standardized 8-herb dietary supplement prepared by proprie tary extraction/mixing technologies, appears to have a number of health ben efits when given to cancer patients. These include reduction of serum PSA ( prostate specific antigen) in individuals diagnosed with advanced prostate carcinoma, and overall improvement of morbidity and immune status in termin al cancer cases. Since the expression of bcl-6 in T and B lymphocytes has b een reported to be significantly down regulated by mitogens, we reason that the immune boosting effects of PC-SPES could involve the modulation of bcl -6 expression.;Such a hypothesis was tested in the bcl-6 abundant Mutu I ce lls. Specifically, we investigated the effects of PC-SPES in regulating cel l growth, induction of apoptosis, effecting changes in the retinoblastoma g ene RE and the modulation of expression of the bcl-6. Herein we report that proliferation of Mutu I cells was inhibited by a 3-7 day incubation with e thanolic extracts of PC-SPES, with concurrent induction of apoptosis. In ad dition, a dose-dependent reduction of bcl-6 was observed, with no concomita nt change in either the phosphorylated or the unphosphorylated forms of RE. These data raise the possibility that PC-SPES may enhance immune functions in vivo by down-regulating bcl-6 expression. Alternatively, decrease in bc l-6 could serve as a biomarker for testing the efficaciousness of PC-SPES i n vivo.