Hd. Halicka et al., APOPTOSIS AND CELL-CYCLE EFFECTS INDUCED BY EXTRACTS OF THE CHINESE HERBAL PREPARATION PC SPES, International journal of oncology, 11(3), 1997, pp. 437-448
A herbal preparation denoted PC SPES(R) is available in 'natural food'
or 'health food' stores in the United States. This mixture (patent pe
nding, US Serial number 08/697,920) consists of extracts from 8 differ
ent herbs, 7 originating from China and one from America, and is sold
as a dietary supplement. Although several components of this herbal mi
xture were reported to have antiproliferative and/or antitumor activit
y little is known about the possible in vitro cytostatic or cytotoxic
properties of the formulation. Composition of PC SPES is standardized
by HPLC; the ethanol extract is characterized by the presence of 6 dis
tinct components, reproducible from batch to batch. This extract suppr
essed cell proliferation and reduced the clonogenicity of a variety of
human tumor cell lines, including PC-3 and LNCaP prostate carcinomas,
MCF-7 and T47-D breast carcinomas, SK-N-MC neuroepithelioma, Cole 38
melanoma, U937 histiomonocytic lymphoma, as well as HL-60 and MOLT-4 l
eukemias. The sensitivity to PC SPES was different for particular cell
lines, with MCF-7 cells being the most sensitive (IC50 = 20 nl/ml) an
d Cole 38 the most resistant (IC50 = 430 nl/ml) in clonogenicity assay
s. The predominant cell cycle effect induced by PC SPES was the prolon
gation of G(1) phase. Apoptosis was observed after exposure of tumor c
ells to PC SPES for 48 h and longer. PC SPES also downregulated expres
sion of bcl-2, the gene protecting cells against apoptosis (studied in
U937 cells) and sensitized these cells to gamma-irradiation. The cell
cycle progression of mitogen stimulated human lymphocytes was not aff
ected at PC SPES concentrations which induced cytotoxic and cytostatic
effects in tumor cells. The data indicate that PC SPES is cytostatic
and cytotoxic for different tumor cell lines and modulates the cell's
propensity to undergo apoptosis.