Department of Zoology, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, P.R. China.
Activation of the cell death program (apoptosis) is a strategy for the treatment of human cancer, and unfortunately a large number of drugs identified as cell cycle-specific agents for killing cancer cells are also toxic to normal cells. The present study demonstrates that the polysaccharide peptide (PSP) extracted from the Chinese medicinal mushroom, Coriolus versicolor, used in combination therapy in China, has the ability to lower the cytotoxicity of certain anti-leukemic drugs via their interaction with cell cycle-dependent and apoptotic pathways. Flow cytometry analysis demonstrated that pre-treatment of PSP (25-100 microg/ml) dose-dependently enhanced the cell cycle perturbation and apoptotic activity of doxorubicin (Doxo) and etoposide (VP-16), but not cytarabine (Ara-C) in human promyelocytic leukemia HL-60 cells. The antagonistic result from combined treatment with Ara-C and PSP may be caused by the removal of HL-60 cells in the G1-S boundary by PSP before exposure to Ara-C. A negative correlation between the increase in apoptotic cell population (pre-G1 peak) with the S-phase cell population expression (R2=0.998), the expression of cyclin E expression (R2=0.872) and caspase 3 activity (R2=0.997) suggests that PSP enhanced the apoptotic machinery of Doxo and VP-16 in a cell cycle-dependent manner and is mediated, at least in part, by the PSP-mediated modulation of the regulatory checkpoint cyclin E and caspase 3. This study is the first to describe the cell cycle mechanistic action of PSP and its interaction with other anticancer agents. Our data support the potential development of PSP as an adjuvant for leukemia treatment, but also imply the importance of understanding its interaction with individual anticancer agents.
Department of Zoology, The University of Hong Kong, Pokfalum Road, Hong Kong, SAR, P.R. China.
The polysaccharide peptide (PSP) isolated from the mycelia of Chinese Medicinal fungus Coriolus versicolor has proven benefits in clinical trials in China but the mechanism of action has not been elucidated. In this study, HL-60 cell line was used to investigate the anti-proliferation and cell death process of PSP. The cytotoxicity of PSP on normal human T-lymphocytes was also evaluated. We show that PSP induced apoptosis of human promyelocytic leukemia HL-60 cells but not of normal human T-lymphocytes. The apoptotic machinery induced by PSP was associated with a decrease in Bcl-2/Bax ratio, drop in mitochondrial transmembrane potential, cytochrome c release, and activation of caspase-3, -8 and -9. Activation of the cellular apoptotic program is a current strategy for the treatment of human cancer, and the selectivity of PSP to induce apoptosis in cancerous and not on normal cells supports its development as a novel anticancer agent.
Department of Pharmacology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China. cslkel@hotmail.com
Polysaccharide peptide (PSP), isolated from Coriolus versicolor COV-1, has been shown to restore the immunological effects against cyclophosphamide-induced immuno-suppression, although the mechanism(s) involved remain uncertain. This study investigated the PSP-cyclophosphamide interaction by studying the effects of PSP on the pharmacokinetic of cyclophosphamide in the rat and the effect of PSP on the cytotoxic effects of cyclophosphamide on a cancer cell line (HepG2 cells). In the pharmacokinetic studies in the rat, acute pre-treatment of PSP (4 micromol/kg/day, i.p.) decreased the clearance (CL) of cyclophosphamide by 31%, with a concomitant increase in the area under concentration-time curve (AUC) by 44%, and prolongation of the plasma half-life (T(1/2)) by 43%. Sub-chronic pre-treatment of PSP (2 micromol/kg/day, i.p., 3 days) decreased the CL of cyclophosphamide by 33%, with a concomitant increase in the AUC by 50%, and prolongation of the plasma T(1/2) by 34%. In cytotoxicity studies using HepG2 cells, non-toxic dose of PSP (1-10 microM) enhanced the cytotoxicity of cyclophosphamide. PSP at 10 microM further decreased HepG2 cell viability by 22% compared to when cyclophosphamide was present alone. In summary, PSP enhanced the cytotoxic effect of cyclophosphamide on a cancer cell line in vitro and altered the pharmacokinetics of cyclophosphamide in vivo in the rat. Both of these effects may be beneficial in the use of PSP as an adjunct to cyclophosphamide treatment.
L.Z. Xu Laboratory of Pathology Cancer Institute, Shanghai Medical University
Abstract
In the present study the anti-cancer effect of polysaccharide peptide of Coriolus versicolor Cov-1 (PSP) was compared with polysaccharide peptide of Coriolus versicolor CM-101 (PSK) on four human tumor cell line targets (SGC 7901, stomach cancer cell; SPC, human lung adenocarcinoma cell; SLY, human monocytic leukemia cell and Mei, human skin histiocytic lymphoma cell) in Vitro.
PSP had similar cytotoxic effects upon human tumor cells as PSK, both inhibiting cell growth. In comparison with control specimens, the SPC cell line treated with PSP (1000ug/ml) for 72 hours at 37oC showed marked morphological changes such as cell swelling, chromatin aggregation, formation of polynuclear cells and sawtooth on the surface of cell nuclei.
PSK as a new immunomodulative drug had been widely used for clinical anticancer therapy in Japan. When combined with chemotherapy, radiotherapy and surgical operation, PSK is found to be able to improve the therapeutic effects. In 1983, a polysaccharide peptide of Coriolus versicolor Cov-1 was isolated from the mycelia by Qing-yao Yang. It is possessed of physio-chemical characteristics similar to PSK and designated as PSP. In the present study the anti-cancer effect of PSP was compared with PSK using four human tumor cell line targets in vitro.
Department of Physiology, Faculty of Medicine, University of Hong Kong, Hong Kong.
Coriolus versicolor polysaccharide peptide (CVP) and the bis-benzylisoquinoline alkaloids, tetrandrine (TET) and berbamine (BER), the active ingredients isolated from Chinese medicinal herbs known to possess antitumor activities, concentration-dependently inhibited the proliferation of human leukemic HL-60 cells. CVP did not affect the growth of normal human peripheral blood lymphocytes (PBL), whereas TET elicited concentration-dependent cytotoxic effects. Morphological observation and DNA analysis revealed that CVP elicited no effect on the morphological features of HL-60 cells and did not cause DNA fragmentation, but TET and BER caused cell shrinkage with the formation of apoptotic bodies, and showed clear evidence of DNA fragmentation. These findings indicate that TET and BER, but not CVP, inhibited the proliferation of HL-60 cells via induction of apoptosis.
W.C. Xue and T.F. Liu
Cancer Hospital, Shanghai Medical University
Abstract
There is no really effective treatment for moderate and advanced stages of esophageal
carcinoma. Although surgery for the earlier cases has been able to give a 5 years survival
rate of 28.7%, such operable cases are relatively few. By far the greater majority are
already in stage III to IV when first seen in the clinic, and radiotherapy alone in these cases
has given a 5 years survival rate of only 8-14%. In order to improve treatment results, a
variety of chemotherapeutic agents have been used in combination surgery, but so far no
really effective drug has been found.
The drug PSP (polysaccharide-peptide of Coriolus versicolor) has been discovered and
produced by Professor Qing-yao Yang of. It is a new anti-cancer and immuno-regulatory
drug, similar to PSK (Krestin) but the effective component has been found to be larger
than PSK. Experimental data has proved these properties of PSP, and in vitro as well as
in vivo studies have all proved that PSP is superior to PSK. Of course, as is the case with
all new drugs, the ultimate proof of its value will have to be shown by clinical application.
Data on Krestin suggest that this family of drugs when used in combination with
radiotherapy, there might be an increase of the biological effects of radiation. To do a
pilot study on such a possibility, the authors have treated 41 moderate to advanced cases of
esophageal carcinoma with a combination of PSP and radiotherapy.
The protein-bound polysaccharide preparation, PS-K, isolated from a mushroom, Coriolus versicolor, was found to stimulate human lymphocytes and induce them into blastogenesis in vitro. This stimulatory effect seemed to be nonspecific since lymphocytes from cord blood of newborn babies were also stimulated by PS-K. The highest lymphocyte blastogenesis by PS-K was observed after 5 days in culture.
The influence of PSK, a protein bound polysaccharide from Coriolus versicolor on various immunological parameters was studied, PSK was found to enhance B cell activity as measured by the spleen plaque-forming cell assay in mice, and to stimulate mouse macrophages as determined by an enhancement of carbon clearance and an increase in the phagocytosis of opsonized sheep red blood cells by peritoneal mouse macrophages in vitro. The activation of mouse macrophages by PSK appeared to correlate with the therapeutic effects of the compound. In mice made granulocytopenic with cyclophosphamide and subsequently infected with a variety of garm-negative pathogens or with Candida albicans, PSK prolonged the average survival time of the animals. The compound also led to a drastic increase in the number of animals surviving such experimental infections as compared to untreated controls. Possible mechanisms responsible for these protective effects by PSK are discussed.
To investigate the mechanism of tumor growth enhancement induced by operative stress in rats, laparo-thoracotomy was performed on day 2 after tumor cell inoculation associated with administrations of various kinds of immunopotentiators. OK-432 (Streptococcal preparation), PS-K (extract from mycelium of Coriolus Versicolor), Lentinan (extract from Lentinus Edodus) and C. parvum were administered intravenously or intraperitoneally in the fractionated form prior to or after inoculation. In general, administration of each immunopotentiator, except for Lentinan, resulted in a recovery from the reduction in survival days after laparo-thoracotomy. In particular, OK-432 administration prior to inoculation showed a significant improvement.
Female C3H/He mice aged 10 weeks with transplanted MM46 tumor were used in an investigation of the timing of administration of immunomodulators, such as PSK (a protein-bound polysaccharide prepared from Coriolus versicolor), OK-432 (streptococcal preparation), bestatin (inhibitor of aminopeptidase B) combined with two fractionated local irradiation with the total dose of 3,000 rad. The daily dose of 250 mg/kg of PSK, 1.0 KE/mouse of OK-432, or 300 micrograms/mouse of bestatin were injected intraperitoneally for 4 consecutive days before or after irradiation. The antitumor effect was evaluated by the changes of tumor volume and survival curves. When PSK or OK-432 was administered after irradiation, tumor growth was decreased and 60-day survival rate and survival curve were significantly elongated compared with the control group and the group to which PSK or OK-432 were administered before irradiation (p less than 0.025, p less than 0.05, respectively). As for bestatin, no remarkable difference was observed irrespective of the timing of administration. These results suggested that some immunomodulators show different antitumor activity depending on the combined timing relative to radiotherapy.