PC-SPES (PDQ®): Complementary and alternative medicine - Health Professional Information [NCI] - Laboratory / Animal / Preclinical Studies
In another study evaluating regulation of PSA expression and androgen receptor (AR) activity, LNCaP prostate cancer cell lines showed downregulation of both proliferating cell nuclear antigen (PCNA) and PSA expression. PSA changes occurred concurrently with the decrease of PCNA. The results suggest that PC-SPES modulates cell growth by changing PCNA expression and may decrease PSA levels indirectly by suppressing AR expression.
None of the studies above indicated lot number or year of manufacture of the PC-SPES used. Therefore, it is not possible to assess the amount of contamination of the mixtures used in the studies or whether the mixtures used were not in fact contaminated.
A 1998 study that evaluated estrogenic activity of extracts of PC-SPES, ginseng (Panax ginseng C.A. Meyer), saw palmetto, DES, and estrone (estradiol -17 beta) in vitro reported on the estrogenic response of ovariectomized CD-1 mice to PC-SPES extract as well as the response to PC-SPES capsules in eight prostate cancer patients who had received previous therapy.  This study used four samples of PC-SPES ordered in separate purchases from BotanicLab. No lot numbers were supplied in the study. Lot numbers from October 1996 through July 1998 were later tested for contamination and had DES levels of 114.74 μg/g to 159.27 μg/g, as well as the highest detected levels of indomethacin of the PC-SPES lots tested.In vitro tests of PC-SPES extract or estradiol showed estrogenic activity similar to 1 nM estradiol on estrogen receptor Y253 yeast strain. Transcriptional activation assays in yeast strain PL3 Saccharomyces cerevisiae with ethanolic extract of PC-SPES exhibited estrogen-like effects. In the eight prostate cancer patients, serum testosterone concentrations decreased during the use of PC-SPES and increased within 3 weeks after treatment was discontinued. PSA levels decreased in all eight patients. Side effects in all eight patients were similar to those seen after treatment with estrogen: breast tenderness and loss of libido. One patient had superficial venous thrombosis. In addition to baicalin, two other compounds purified from PC-SPES, isoliquiritigenin and wogonin, have been shown to reduce PSA levels and downregulate AR.