We examined the effect of PSK, a protein-bound polysaccharide, upon in vivo metastasis and in vitro invasion of the B16-BL6 mouse melanoma cells. (1) PSK suppressed in vivo artificial and spontaneous lung metastases of B16-BL6 in C57BL/6 mice. (2) PSK in a dose-dependent fashion suppressed in vitro invasion and chemotaxis of the tumor cells using filters coated with a reconstituted basement membrane. (3) PSK had little effect on DNA synthesis in tumor cells in vitro, but suppressed tumor cell adhesion to, degradation of, and haptotaxis to components of the basement membrane. (4) PSK suppressed the binding of tumor cells to components of the basement membrane. These findings suggest that PSK may suppress metastasis through inhibition of tumor cell invasion and that this effect is the result of interactions between PSK and components of the basement membrane.
The anticancer effects of PSP purified products, PSP-A, PSP-B, PSP-C and crude product PSP-Cr and KS-2 were compared on four human tumor cell lines in vitro. It was found that the inhibition rate of cell proliferation of PSP-A was higher than that of PSP-Cr, PSP-B and PSP-C (P<0.05). On SPC cells, the inhibition rate of PSP-A at a dosage of 1000ug/ml was 62.7%, being the highest as compared with those on the other three cell lines.
The effect of the inhibition of KS-2 on Mei tumorous cells is obvious. Its inhibition rate is 62.5%.
Morphological changes were seen in all the four cell lines, especially in SPC cells after PSP-A treatment.
The immunomodulating action of two mushroom antitumor polysaccharides, polysaccharide-protein complex (PSPC) and lentinan, was elucidated through analysing the expression profile of cytokines during a time course (0 h to 48 h) after their administration. Among the 5 cytokine genes, the induction of a marked increase in the mRNA levels of IL-la, IL-lp, TNF-a, IFN-)I and M-CSF by PSPC and lentinan was observed in the peritoneal exudate cells and splenocytes. However, the time point of their increased production was different after PSPC and lentinan administration.
To evaluate the efficacy of PSK for adjuvant immuno-chemotherapy in patients who had undergone radical gastrectomy, a randomized controlled trial has been in progress in collaboration with 46 institutions in the Chubu district of Japan. A total of 262 patients were registered for this trial during the two years from July 1985 to June 1987 with a centralized registration system, and were allocated into the 5-FU+PSK group (Group P) and 5-FU alone group (Group C) by the minimization method following the random permuted blocks method. Between the two groups, the parameters of sex, age, serosal invasion (S), lymph-node metastasis (N), and the combination of S . N factor levels were distributed without significant differences. An induction treatment with MMC 6 mg/m2 was given to all patients following curative mastectomy and on the 7th post-operative day. Two weeks after surgery, Group P received alternately PSK 3 g/day for 4 week and 5-FU 150 mg/day for 4 weeks as one course, and 10 courses were given. Group C received 5-FU alone for 4 weeks using alternate rest interval for 4 weeks. Since both experimental and clinical studies suggested that alternate treatments using PSK and anticancer agents were effective, treatment in this trial alternated PSK and 5-FU. A final follow-up study will be completed in June 1992, when all patients shall have survived more than 5 years after surgery. The administration of 5-FU was completed by January. 1989, but PSK has been administered to group P. The period from 18 to 42 months after surgery was reached in all eligible patients (253) at the end of December 1988. The disease-free survival curves and overall survival curves of group P were significantly (p = 0.018 and p = 0.045,) better than those of group C.
A total of 103 patients with advanced gastric carcinoma were randomized after curative surgery to receive an alternate administration of carabzilquinone (CQ) and PSK (Krestin) or carbazilquinone alone. Each course of therapies started 1 week after the surgical operation and therapy schedules consisted of 9 courses. In each course of 6 weeks, CQ was administered on day 0, 8, and 15. In combined immunochemotherapy group, PSK was given orally in 3-divided doses of 2g/m^2/day from the day of the third CQ administration for consecutive 4 weeks. Estimated survival rate and cumulative survival curve were compared untilizing the data up to 7 years after the operation. There was no overall significant difference in survival rates between the CQ plus PSK group and the CQ alone group, but a group of patients survived significantly longer when treated with the combination of CQ and PSK. Neither in more advanced cases nor in cancers of early stages, the addition of PSK provided an additive effect. The favorable result obtained in one subgroup treated with PSK, suggests that the use of this agent in treating gastric cancers should be carefully evaluated in terms of serosal infiltration and nodal metastasis.?
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A total of 103 patients with advanced gastric carcinoma were randomized after curative surgery to receive an alternate administration of carbazilquinone (CQ) and PSK (Krestin) or carbazilquinone alone. Each course of therapies started 1 week after the surgical operation and therapy schedules consisted of 9 courses. In each course of 6 weeks, CQ (2 mg/m2/week) was administered on day 0, 8, and 15. In combined immunochemotherapy group, PSK was given orally in 3-divided doses of 2 g/m2/day from the day of the third CQ administration for consecutive 4 weeks. Estimated survival rate and cumulative survival curve were compared utilizing the data up to 7 years after the operation. There was no overall significant difference in survival rates between the CQ plus PSK group and the CQ alone group, but a group of patients whose disease was classified as S1 + S2(N1-2) survived significantly longer when treated with the combination of CQ and PSK. Neither in more advanced cases (greater than S3 or greater than N3) nor in cancers of early stages, the addition of PSK provided an additive effect. The favorable result obtained in one subgroup treated with PSK, suggests that the use of this agent in treating gastric cancers should be carefully evaluated in terms of serosal infiltration and nodal metastasis.
PURPOSE: Intravenous fluorouracil and leucovorin for six to eight months is currently a standard adjuvant treatment for Stage III colon cancer; however, this regimen is complex, inconvenient, and has a high intolerability. Adjuvant chemotherapies are claimed for objective response rates with an acceptable safety profile and complexity. We investigated the benefits of oral protein-bound polysaccharide K added to oral tegafur/uracil on curatively resected Stage II or III colorectal cancer. METHODS: We prospectively randomized 207 patients to treatments of either oral 3.0 g protein-bound polysaccharide K plus 300 mg tegafur/uracil or 300 mg tegafur/uracil alone for two years following 12 mg/m2 and 8 mg/m2 mitomycin treatment on postoperative Days 1 and 2, respectively. The primary end points were disease-free and overall survival, and recurrence rates. RESULTS: Three (1.4 percent) patients were declared ineligible, and three patients did not start treatment. In total, 201 patients were analyzed. The three-year, disease-free survival rate was 80.6 percent (standard error = 3.4 percent) in the protein-bound polysaccharide K group (P = 0.02) compared with 68.7 percent (SE = 5.7 percent) in the control group after a median follow-up of 3.7 years. The estimated relative risk of recurrence in the control group was 1.87 (95 percent confidence interval, 1.10-3.20) at three years. The three-year, overall survival rate was 87.3 percent (standard error = 2.9 percent) in the protein-bound polysaccharide K group and 80.6 percent (standard error = 4.8 percent) in the control group (P = 0.24). The three-year, overall survival rate in 80 pathological TNM Stage III patients was 83.0 percent (standard error = 5.2 percent) in the protein-bound polysaccharide K group and 59.3 percent (standard error = 9.5 percent) in the control group (P = 0.02). Protein-bound polysaccharide K prevented distant metastases (P = 0.05), particularly lung metastases (P = 0.01). The incidence of adverse effects was minimal, and compliance was good. CONCLUSION: Adjuvant therapy using a combination of oral protein-bound polysaccharide K and tegafur/uracil is highly effective in preventing the recurrence of colorectal cancer in Stage II or III patients, and increases overall survival in pathological TNM Stage III. These results will be a sufficient proof to conduct a larger study to compare tegafur/uracil/protein-bound polysaccharide K with 5-fluorouracil/leucovorin.
A controlled study using adjuvant PSK immunotherapy in patients with nasopharyngeal carcinoma was initiated with the aim of improving survival by enhancing the host immune system against tumour cells. A total of 38 patients were randomly selected, all of whom had previously received radiotherapy with or without chemotherapy. Eight patients in the PSK immunotherapy group (n = 21) developed local recurrence, three of whom later died due to distant metastasis. In the control group (n = 17) three patients developed local recurrence while six patients developed distant metastasis. All of these six patients later died due to disease progression. It seems that PSK exerts its antitumour effect systemically; the risk of distant metastasis occurring is decreased, but it is apparently ineffective in improving local disease control. The estimated median survival time of the PSK-treated group compared with the control was significantly increased (35 months versus 25 months, P = 0.043). The 5-year survival rate was also significantly better in the PSK immunotherapy group (28% versus 15%, P = 0.043). It is concluded that PSK deserves careful consideration as an important immunotherapeutic agent in the management of nasopharyngeal carcinoma.
Intravenous fluorouracil and leucovorin is the standard adjuvant treatment for stage III colon cancer. However, oral adjuvant chemotherapy is attractive because it has low toxicity and greater convenience. We investigated the benefits of oral protein-bound polysaccharide K (PSK) with tegafur/uracil (UFT) as an adjuvant in stage II and III colorectal cancer. Patients were assigned to groups that received either 3 g PSK plus 300 mg UFT, or 300 mg UFT alone orally each day for a 2-year period following intravenous mitomycin C. Of 207 registered patients, 205 with stage II (n¼123) or III (n¼82) were analysed. The 5-year disease-free survival was 73.0% (95% CI 65.6–80.4%) with PSK (n¼137) and 58.8% (95% CI 47.1–70.5%) in the controls (n¼68) (P¼0.016). POLYSACCHARIDE K reduced the recurrence by 43.6% (95% CI 4.5–66.7%) and mortality by 40.2% (95% CI _12.5 to 68.3%). The 5-year survival was 81.8% (95% CI 75.3–88.2%) in the PSK group and 72.1% (95% CI 61.4–82.7%) in the control group (P¼0.056). In stage III patients, disease-free and overall survivals in patients receiving PSK were increased significantly: 60.0% (95% CI 47.1–72.9%) and 74.6% (95% CI 63.0–86.1%) in the PSK group as compared with 32.1% (95% CI 14.8–49.4%) and 46.4% (95% CI 28.0–64.9%) in the controls (P¼0.002 and 0.003, respectively). Polysaccharide K prevented recurrence, particularly lung metastases (P¼0.02; odds ratio 0.27; 95% CI 0.09–0.77). In the models, the presence of regional metastases (relative risk, 2.973; 95% CI 1.712–5.165; Po0.001), omission of PSK (relative risk, 2.106; 95% CI 1.221–3.633; P¼0.007), and higher primary tumour (relative risk, 4.398; 95% CI 1.017–19.014; P¼0.047) were each significant indicators of recurrence. Adverse effects were mild and compliance was good. Oral PSK with UFT reduced recurrence in stage II and III colorectal cancer, and increased survival in stage III.
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 ?g/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.
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