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Trametes versicolor, the mushroom from which PSK was isolated.

Polysaccharide-K (Krestin, PSK) is a protein-bound polysaccharide, which is used as an anticancer immunologic adjuvant in some countries.

PSK is isolated from the fruitbody of Trametes versicolor. Preliminary evidence indicates PSK has anticancer activity in vitro,[1] in vivo[2] and in human clinical trials.[3] Preliminary research has also demonstrated that PSK may inhibit various cancer onset mechanisms.[4] Preliminary evidence indicates PSK may have use as an adjuvant in the treatment of gastric, esophageal, colorectal, breast and lung cancers.[5] Human clinical trials suggest PSK may affect cancer recurrence when used as an adjuvant,[3][6] and basic research has demonstrated it inhibited certain human cancer cell lines in vitro.[7][8][9]

The MD Anderson Cancer Center reported that it is a "promising candidate for chemoprevention due to the multiple effects on the malignant process, limited side effects and safety of daily oral doses for extended periods of time."[10] The Therapeutic Goods Administration in Australia reported that the WHO has only eight records of adverse effects with PSK and none reported for PSP.[11]

Research summary[edit]

In conjunction with chemotherapy, PSK has increased the survival time of cancer patients in randomized, control studies, with stomach cancer (meta-analysis of 8,009 patients),[3] colorectal cancer (randomized, controlled study of 448 patients),[12] non-small cell lung carcinoma,[13][unreliable medical source?] and small cell carcinoma of the lungs.[citation needed] PSK has produced mixed results with breast cancer,[14][unreliable medical source?] liver cancer,[15] and leukemia.[16][original research?]

PSK chemistry[edit]

PSK is a protein polysaccharide consisting of a beta-glucan β-1,4 main chain with β-1,3 and β-1,6 side chains. The approximate molecular weight of PSK is 100,000 Da, and the protein component is reported at the β-1,6 side chain.[4] PSK is isolated from the "CM-101" strain of Trametes versicolor. The analogous compound PSP, is derived from the "COV-1" strain of Trametes versicolor.[5]

See also[edit]


  1. ^ Jiménez-Medina E, Berruguilla E, Romero I, et al. (2008). "The immunomodulator PSK induces in vitro cytotoxic activity in tumour cell lines via arrest of cell cycle and induction of apoptosis". BMC Cancer. 8: 78. doi:10.1186/1471-2407-8-78. PMC 2291471Freely accessible. PMID 18366723. 
  2. ^ Yamasaki A, Shoda M, Iijima H, et al. (March 2009). "A protein-bound polysaccharide, PSK, enhances tumor suppression induced by docetaxel in a gastric cancer xenograft model". Anticancer Research. 29 (3): 843–50. PMID 19414318. 
  3. ^ a b c Oba K, Teramukai S, Kobayashi M, Matsui T, Kodera Y, Sakamoto J (June 2007). "Efficacy of adjuvant immunochemotherapy with polysaccharide K for patients with curative resections of gastric cancer". Cancer Immunology, Immunotherapy. 56 (6): 905–11. doi:10.1007/s00262-006-0248-1. PMID 17106715. 
  4. ^ a b Kobayashi H, Matsunaga K, Oguchi Y (1995). "Antimetastatic effects of PSK (Krestin), a protein-bound polysaccharide obtained from basidiomycetes: an overview". Cancer Epidemiology, Biomarkers & Prevention. 4 (3): 275–81. PMID 7606203. 
  5. ^ a b Fisher M, Yang LX (2002). "Anticancer effects and mechanisms of polysaccharide-K (PSK): implications of cancer immunotherapy". Anticancer Research. 22 (3): 1737–54. PMID 12168863. 
  6. ^ Sugimachi K, Maehara Y, Ogawa M, Kakegawa T, Tomita M (1997). "Dose intensity of uracil and tegafur in postoperative chemotherapy for patients with poorly differentiated gastric cancer". Cancer Chemotherapy and Pharmacology. 40 (3): 233–8. doi:10.1007/s002800050652. PMID 9219507. 
  7. ^ Hsieh TC, Wu JM (January 2001). "Cell growth and gene modulatory activities of Yunzhi (Windsor Wunxi) from mushroom Trametes versicolor in androgen-dependent and androgen-insensitive human prostate cancer cells". International Journal of Oncology. 18 (1): 81–8. doi:10.3892/ijo.18.1.81. PMID 11115542. 
  8. ^ Dong Y, Yang MM, Kwan CY (1997). "In vitro inhibition of proliferation of HL-60 cells by tetrandrine and coriolus versicolor peptide derived from Chinese medicinal herbs". Life Sciences. 60 (8): PL135–40. doi:10.1016/S0024-3205(96)00695-9. PMID 9042394. 
  9. ^ Yang MM, Chen Z, Kwok JS (1992). "The anti-tumor effect of a small polypeptide from Coriolus versicolor (SPCV)". The American Journal of Chinese Medicine. 20 (3–4): 221–32. doi:10.1142/S0192415X92000230. PMID 1471606. 
  10. ^ "Coriolus versicolor". Complementary and alternative therapies for cancer patients. San Diego: University of California. 
  11. ^ http://www.tga.gov.au/docs/pdf/cmec/cmecmi55.pdf
  12. ^ Mitomi T, Tsuchiya S, Iijima N, et al. (February 1992). "Randomized, controlled study on adjuvant immunochemotherapy with PSK in curatively resected colorectal cancer. The Cooperative Study Group of Surgical Adjuvant Immunochemotherapy for Cancer of Colon and Rectum (Kanagawa)". Diseases of the Colon and Rectum. 35 (2): 123–30. doi:10.1007/BF02050666. PMID 1735313. 
  13. ^ Hayakawa K, Mitsuhashi N, Saito Y, et al. (1997). "Effect of Krestin as adjuvant treatment following radical radiotherapy in non-small cell lung cancer patients". Cancer Detection and Prevention. 21 (1): 71–7. PMID 9043766. 
  14. ^ Iino Y, Yokoe T, Maemura M, et al. (1995). "Immunochemotherapies versus chemotherapy as adjuvant treatment after curative resection of operable breast cancer". Anticancer Research. 15 (6B): 2907–11. PMID 8669887. 
  15. ^ Suto T, Fukuda S, Moriya N, et al. (1994). "Clinical study of biological response modifiers as maintenance therapy for hepatocellular carcinoma". Cancer Chemotherapy and Pharmacology. 33 Suppl: S145–8. doi:10.1007/BF00686688. PMID 8137477. 
  16. ^ Ohno R, Yamada K, Masaoka T, et al. (1984). "A randomized trial of chemoimmunotherapy of acute nonlymphocytic leukemia in adults using a protein-bound polysaccharide preparation". Cancer Immunology, Immunotherapy. 18 (3): 149–54. doi:10.1007/BF00205503. PMID 6391658. 

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