Biomedical Research Laboratories, Kureha Chemical Industry, Co., Ltd., Tokyo, Japan.
Abstract
We investigated the effect of PSK, a protein-bound polysaccharide obtained from Coriolus versicolor of basidiomycetes, on antitumor immunity in tumor-bearing mice. PSK prolonged significantly the life span of C3H/He mice bearing syngeneic plasmacytoma X5563 in a schedule- and dose-dependent manner. PSK was most effective when administered at 100 mg/kg every other day ten times starting from the day after tumor inoculation. The administration of PSK enhanced significantly the cytostatic activity of peritoneal exudate plastic-adherent cells and the cytolytic activity of spleen cells after in vitro incubation with mitomycin C-treated tumor cells. In addition, PSK restored the cytokine-producing capacity of spleen cells suppressed in tumor-bearing mice after in vitro incubation with mitogen. Sera from tumor-bearing mice suppressed the activity of such effector cells as well as the interleukin 2-producing capacity of spleen cells, but sera from PSK-treated tumor-bearing mice prevented this suppression. These results suggest that PSK enhances antitumor immunity by reducing immunosuppressive activity of serum from tumor-bearing mice.
Department of Anatomy, Faculty of Medicine, Chinese University of Hong Kong, Shatin.
Abstract
Polysaccharopeptide (PSP) is a substance produced by an edible mushroom, Coriolus versicolor which has been claimed to possess antitumor activity. However, neither tumoricidal activity nor cytotoxicity was observed when five tumor cell lines and mouse peritoneal macrophages were cultured in vitro in the presence of 2.5-10 micrograms/ml PSP. An increase in the production of reactive nitrogen intermediates, reactive oxygen intermediates (superoxide anions) and tumor necrosis factor was measured in peritoneal macrophages collected from inbred C57 mice which had received PSP in the drinking water for 2 weeks. Northern blot analysis also demonstrated that PSP activated the transcription of tumor necrosis factor gene in these cells, indicating that PSP exerted an immunomodulatory effect on the defensive cells.
Third Department of Internal Medicine, Asahikawa Medical College, Japan.
Abstract
Granulocyte-colony-stimulating factor (G-CSF), granulocyte/macrophage-colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) were used in combination with PSK, a protein-bound polysaccharide extracted from mycelium of Coriolus versicolor (strain CM101), in myelosuppressed mice. The myelosuppression model consisted of BDF1 mice who received 150 mg/kg 5-fluorouracil (5-FU) intravenously. The peripheral blood leukocyte count during the recovery stage was significantly increased when these cytokines were administered with PSK compared to when the cytokines were used individually. In vitro colony assay revealed that the combination of PSK and any of GM-CSF, IL-3 or stem cell factor (SCF) showed a greater increase in colony numbers than when these materials were administered individually, although G-CSF did not show a synergistic effect with PSK. When bone marrow cells were obtained from mice which had been given PSK or IL-3, the colony assays were made in the presence of PSK or IL-3 in vitro. The greatest increase in the numbers was observed in colonies of the cultured group in the presence of IL-3 after the PSK priming. However, the colony formation potential of PSK was not inhibited by addition of anti-SCF antibody. The above results indicate that the combined administration of PSK with G-CSF, GM-CSF or IL-3 increased the hematological recovery of myelosuppressed mice. Moreover, the phase at which PSK has effects on hematopoietic cells seems to be at a more immature level than with IL-3. The combined administration of PSK and the above cytokines may improve myelosuppression after chemotherapy in patients with malignancy.
Molecular Biology Laboratory, Kitasato University School of Medicine, Kanagawa, Japan.
Abstract
The protein-bound polysaccharide of Coriolus versicolor QUEL (PS_K) expresses superoxide dismutase (SOD) mimicking activity. Examination was made of the effects of PS-K on cancer cell lines following administration of the anti-cancer drug cisdiaminedichloroplatinum (cisplatin). Cell proliferation of each cell line was inhibited markedly by cisplatin from 0.5 to 5 micrograms/0.5 ml per well. Fifty percent of the inhibitory concentration (IC50) was 0.33 micrograms/0.5 ml per well in NRK-49F and human ovarian cancer cells, and 1.5 micrograms/0.5 ml per well in H4-II-E. PS-K 50 micrograms/0.5 ml per well prevented cytotoxicity due to cisplatin toward NRK-49F, but enhanced the cytotoxicity on H4-II-E and human ovarian cancer cells. Increase in lipid peroxide and decrease in SOD activity were observed following an IC50 dose of cisplatin. With PS-K 50 micrograms/0.5 ml per well, all the above were augmented in H4-II-E and ovarian cancer cells, but diminished in NRK-49F cell line. PS-K may have effect on cancer patients through its combining with cisplatin.
Molecular Biology Laboratory, Kotasato University School of Medicine, Kanagawa, Japan.
Abstract
The protein-bound polysaccharide of Coriolus versicolor QUEL (PS-K) expresses the mimicking activity of superoxide dismutase (SOD). Examination was made of the suppressive effects of PS-K on cancer cell lines cultured in vitro. The SOD activity of LLC-WRC-256 (Walker 256 fibrosarcoma) cell lines was less than that of NRK-49F (rat normal kidney fibroblast), H4-II-E (rat hepatoma) and H4-II-E-C3 (rat hepatoma) cell lines. This activity in Walker 256 fibrosarcoma cells increased by 3.6 times and H2O2 concentration, by 2.56 times by PS-K 500 micrograms/ml. Cell proliferation was consequently suppressed and living cells decreased to less than 50% of the cells cultured without PS-K. Catalase and glutathione peroxidase activity changed little by PS-K. The sensitivity of cancer cells to PS-K can be predetermined based on SOD activity in tumor tissue.
Molecular Biology Laboratory, Kitasato University School of Medicine, Kanagawa, Japan.
Abstract
The protein-bound polysaccharide of Coriolus versicolor QUEL (PS-K) expresses superoxide dismutase (SOD) mimicking activity. Examination was made of the suppressive effects of PS-K on cancer cell lines cultured in vitro. SOD activity of incorporated PS-K was 5.88 u/mg in LLC-WRC-256 (Walker 256 fibrosarcoma) cells and 4.73 u/mg in NRK-49F (rat normal kidney fibroblast) cells. SOD activity in both cell types was enhanced about 7-8 times that of the original PS-K. PS-K was not incorporated into H4-11-E or H4-11-E-C3 (rat hepatoma) cells. SOD activity of 1 mg/ml PS-K incubated with cell homogenates of LLC-WRC-256 cells for 6 hours increased from 0.68 u/mg to 1.35 u/mg. SOD activity of PS-K 1 mg/ml in 0.05 M phosphate buffer incubated with 50 microM NADPH increased from 0.68 u/mg. The consumption of NADPH at the same concentration was confirmed spectrophotometically by incubation with PS-K. The mechanism for the enhancement of SOD activity associated with PS-K is considered to be collaboration with NADPH as an electron donor in the cytoplasm of cancer cells whose SOD and coupling enzyme activities are significantly lower than in normal cells.
Kureha Chemical Ind. Co., Ltd., Biomedical Research Laboratories, Tokyo, Japan.
Abstract
The antitumor effects of a monoclonal antibody against a human cancer cell line and a protein-bound polysaccharide, PSK, obtained from cultured mycelia of Coriolus versicolor in basidiomycetes were examined. The IgG2a monoclonal antibody against the human colon cancer cell line colo 205 induced in vitro antibody-dependent macrophage-mediated cytotoxicity against the cancer cells, but only slightly suppressed the in vivo growth of the cancer cells. Concurrent use of PSK with the antibody enhanced the in vitro antibody-dependent macrophage-mediated cytotoxicity as well as the in vivo antitumor activity. These findings suggest that the combined use of a monoclonal antibody and PSK, which have different modes of action, may be useful in the treatment of cancer.
Department of Forest Products, Faculty of Agriculture, Kyushu University, Fukuoka 812, Japan.
Abstract
To clarify the role of excreted extracellular enzymes during long-term incubation in a pulp biobleaching system with white rot fungi, we developed a cultivation system in which a membrane filter is used; this membrane filter can prevent direct contact between hyphae and kraft pulp, but allows extracellular enzymes to attack the kraft pulp. Phanerochaete sordida YK-624 brightened the pulp 21.4 points to 54.0% brightness after a 5-day in vitro treatment; this value was significantly higher than the values obtained with Phanerochaete chrysosporium and Coriolus versicolor after a 7-day treatment. Our results indicate that cell-free, membrane-filtered components from the in vitro bleaching system are capable of delignifying unbleached kraft pulp. Obvious candidates for filterable reagents capable of delignifying and bleaching kraft pulp are peroxidase and phenoloxidase proteins. The level of secreted manganese peroxidase activity in the filterable components was substantial during strain YK-624 in vitro bleaching. A positive correlation between the level of manganese peroxidase and brightening of the pulp was observed.
Department of Physiology, Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong.
Abstract
RPSP, a refined polysaccharide peptide fraction isolated by fast performance liquid chromatography (FPLC) from the crude powder of total peptide-bound polysaccharides of cultivated Coriolus versicolor Cov-1 dose-dependently inhibited the proliferation of a human hepatoma cell line (HEPG2). The effective dose causing 50% inhibition following 3-day exposure to RPSP was 243 +/- 36 micrograms/ml for HEPG2. However, little or no inhibitory effects were detected in normal human foetal hepatocytes. On the other hand, in the pretreatment group, in which RPSP was administered i.p. for two weeks before sarcoma 180 inoculation in nude mice, the incidence of tumor growth was less (2 out of 5 mice) than that of the control group (all 5 mice). The tumor size of the control group was about 3-5 times bigger than that of the pretreatment group. In tumor-bearing nude mice, 5 days after sarcoma 180 inoculation, i.v. administration of RPSP significantly suppressed the growth of tumor mass. The inhibition rate was 93.6% on day 13. Furthermore, administration of RPSP did not cause any pathological lesions in vital organs of rabbits such as heart, liver, spleen, lung and kidney. In conclusion, these results indicate that RPSP acts by directly suppressing tumor cell growth in vitro and the prevention of in vivo growth of tumor mass is probably mediated also via its immunomodulating effects.
Second Department of Surgery, Gunma University School of Medicine, Maebashi, Japan.
Abstract
OK-432 (picibanil), a streptococcal preparation, has a strong biological response modifier (BRM) function and is expected to produce clinical improvement and prolongation of survival in treated cancer patients in Japan. We were interested in whether OK-432 augments estrogen receptor (ER) levels in breast cancer. To investigate the effect of the BRMs on cellular growth and the characteristics of ER and progesterone receptors (PgR) in the human breast cancer cell line MCF-7, we used OK-432, Krestin (PSK), a protein-bound polysaccharide extracted from Coriolus versicolor, and lentinan, a fungal branched (1…3)-beta-D-glycan. OK432 and PSK dose dependently inhibited DNA synthesis of MCF-7 cells, and the 50% inhibitory concentrations of OK-432 and PSK were 1.2 KE (klinische Einheit, clinical unit)/ml and 200 micrograms/ml, respectively. Lentinan showed no direct anticancer effect in vitro. We found that OK-432 induced a 2-fold increase in ER levels in MCF-7 cells at 0.005 KE/ml, but not in PgR. Lentinan and low-dose PSK did not change ER or PgR levels, but high-dose PSK decreased ER and PgR. We also studied the combined effect of OK-432 and antiestrogens, tamoxifen (TAM) and DP-TAT-59. The combined treatment with OK-432 and TAM showed an additive inhibitory effect on MCF-7 cells. These results suggest that OK-432 may augment the therapeutic effect of TAM in breast cancer.