Polysaccharide-K
Encyclopedia
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
-bound polysaccharide
Polysaccharide
Polysaccharides are long carbohydrate molecules, of repeated monomer units joined together by glycosidic bonds. They range in structure from linear to highly branched. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure,...
, which is used as an immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
boosting agent in the treatment of cancer in some countries in Europe as well as China and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. In Japan, PSK is approved as an adjuvant for cancer therapy and is covered by government health insurance.
PSK is isolated from the mushroom Trametes versicolor
Trametes versicolor
Trametes versicolor — formerly known as Coriolus versicolor and Polyporus versicolor — is an extremely common polypore mushroom which can be found throughout the world. Versicolor means 'of several colours' and it is true that this mushroom is found in a wide variety of different colours. T...
. Preliminary evidence indicates PSK may have anticancer activity in vitro
In vitro
In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...
, in vivo
In vivo
In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...
and in human clinical trials. Preliminary research has also demonstrated that PSK may inhibit various cancer onset mechanisms. Preliminary evidence indicates PSK may have use as an adjuvant in the treatment of gastric, esophageal, colorectal, breast and lung cancers. Human clinical trials suggest PSK may affect cancer recurrence when used as an adjuvant, and basic research has demonstrated it inhibited certain human cancer cell lines in vitro.
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." In fact, the Therapeutic Goods Administration
Therapeutic Goods Administration
The Therapeutic Goods Administration is the regulatory body for therapeutic goods in Australia . It is a Division of the Australian Department of Health and Ageing established under the Therapeutic Goods Act 1989 ...
in Australia reported that the WHO
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
has only eight records of adverse effects with PSK and none reported for PSP.
Observed anti-cancer mechanisms
A 1995 review by Kobayashi et al. found the anti-cancer mechanism of action of PSK is as follows- Suppressing tumor detachment (in vitro and in vivo), intravasationIntravasationAs a part of the process of metastasis, intravasation refers to the invasion of a cancer through the basal membrane and into blood vessels.In radiology, intravasation is used to describe penetration of radiographic contrast into the soft tissue lymphatics and veins of a hollow organ as a result of...
(in vitro), and extravasationExtravasationExtravasation is the accidental administration of intravenously infused medicinal drugs into the surrounding tissue, either by leakage , or direct exposure...
(in vitro). - Suppressing cell matrixExtracellular matrixIn biology, the extracellular matrix is the extracellular part of animal tissue that usually provides structural support to the animal cells in addition to performing various other important functions. The extracellular matrix is the defining feature of connective tissue in animals.Extracellular...
degrading enzymes. - Suppressing tumor induced platelet aggregation (in vitro).
- Suppressing tumor's movement (in vitro and in vivo).
- Suppressing tumor growth (via inhibition of angiogenesisAngiogenesisAngiogenesis is the physiological process involving the growth of new blood vessels from pre-existing vessels. Though there has been some debate over terminology, vasculogenesis is the term used for spontaneous blood-vessel formation, and intussusception is the term for the formation of new blood...
(in vivo) and up-regulation of the immune systemImmune systemAn immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
) (in vitro and in vivo). - Suppressing expression of oncogeneOncogeneAn oncogene is a gene that has the potential to cause cancer. In tumor cells, they are often mutated or expressed at high levels.An oncogene is a gene found in the chromosomes of tumor cells whose activation is associated with the initial and continuing conversion of normal cells into cancer...
c-Ha-ras (in vivo). - Reducing free radicals (in vitro and in vivo).
In addition, In vitro research suggests PSK may enhance the activity of doxorubicin
Doxorubicin
Doxorubicin INN is a drug used in cancer chemotherapy. It is an anthracycline antibiotic, closely related to the natural product daunomycin, and like all anthracyclines, it works by intercalating DNA....
and etoposide
Etoposide
Etoposide phosphate is an anti-cancer agent. It is known in the laboratory as a topoisomerase poison. Etoposide is often incorrectly referred to as a topoisomerase inhibitor in order to avoid using the term "poison" in a clinical setting...
.
Randomized clinical controlled studies
Used in conjunction with chemotherapyChemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
, PSK has increased the survival time of cancer patients in randomized, control studies, with the following types of cancer
- Stomach cancerStomach cancerGastric cancer, commonly referred to as stomach cancer, can develop in any part of the stomach and may spread throughout the stomach and to other organs; particularly the esophagus, lungs, lymph nodes, and the liver...
(meta-analysis of 8,009 patients) - Colorectal cancerColorectal cancerColorectal cancer, commonly known as bowel cancer, is a cancer caused by uncontrolled cell growth , in the colon, rectum, or vermiform appendix. Colorectal cancer is clinically distinct from anal cancer, which affects the anus....
(randomized, controlled study of 448 patients) - Small cell carcinomaSmall cell carcinomaSmall cell carcinoma is a type of highly malignant cancer that most commonly arises within the lung, although it can occasionally arise in other body sites, such as the cervix and prostate....
of the lungs - Non-small cell lung carcinoma
PSK has produced mixed results with the following cancer types.
- Breast cancerBreast cancerBreast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...
- Liver cancerLiver cancerLiver tumors or hepatic tumors are tumors or growths on or in the liver . Several distinct types of tumors can develop in the liver because the liver is made up of various cell types. These growths can be benign or malignant...
- LeukemiaLeukemiaLeukemia or leukaemia is a type of cancer of the blood or bone marrow characterized by an abnormal increase of immature white blood cells called "blasts". Leukemia is a broad term covering a spectrum of diseases...
PSK and PSP
In Japan, the PSK that is used is derived from the "CM-101" strain of Trametes versicolor.In China however, a highly similar PSK formulation is used. The slightly different formulation is known as Polysaccharide Peptide
Polysaccharide Peptide
Polysaccharide peptide is a protein-bound polysaccharide extracted from the edible mushroom Coriolus versicolor. PSP is currently in the animal-testing phase of research in many countries for use as an anti-tumor drug. It appears to work as a Biological Response Modifier, enhancing the body's own...
or PSP, and is derived from a strain of Trametes versicolor known as "COV-1".
Countries that use PSK as an adjuvant for cancer treatment
AustraliaAustralia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
(As part of a commercial pharmacological blend MC-S)
China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
(Approved by Japan's Ministry of Health, Labour and Welfare
Ministry of Health, Labour and Welfare (Japan)
The ' is a cabinet level ministry of the Japanese government. It is commonly known as Kōrō-shō in Japan. This ministry provides regulations on maximum residue limits for agricultural chemicals in foods, basic food and drug regulations, standards for foods, food additives, etc.It was formed with...
in the 1980s)
Partial summary of animal research
Presented below, is a partial list of animal research conducted with PSK| Organ in which cancer is developed | Cancer cell type/line | Result of PSK application |
|---|---|---|
| Lung (spontaneous metastasis) | autochthonous tumor | Increased survival time |
| Lung (spontaneous metastasis) | human prostate cancer (DU-145M, PC-3M) | Increased survival time |
| Lung (spontaneous metastasis) | mouse melanoma (B16-BL6) | Increased survival time |
| Lung (spontaneous metastasis) | rat lung cancer | Increased survival time |
| Liver (spontaneous metastasis) | human lung cancer (AOI) | Suppressed lesion growth |
| Lymph nodes (spontaneous metastasis) | mouse leukemia (P388) | Increased survival time |
| Lymph nodes (spontaneous metastasis) | mouse liver cancer (MH134) | Suppressed lesion growth |
| Liver (artificial metastasis) | rat liver cancer (AH60C) | Suppressed lesion growth |
| Liver (artificial metastasis) | mouse leukemia | Suppressed lesion growth |
| Liver (artificial metastasis) | mouse colon cancer | Suppressed lesion growth, increased survival time |
Research has also demonstrated PSK can help to restore the immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
of immuno-deficient animals.
PSK chemistry
Since PSK is an isolated component of Trametes versicolor, and not an isolated compound, the main structure can only be summarized by close approximations. The approximate molecular weight of PSK is 94,000–100,000 DaAtomic mass unit
The unified atomic mass unit or dalton is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of...
and its main polysaccharide chain consists of a beta-glucan
Beta-glucan
β-Glucans are polysaccharides of D-glucose monomers linked by β-glycosidic bonds. β-glucans are a diverse group of molecules that can vary with respect to molecular mass, solubility, viscosity, and three-dimensional configuration...
linked via β-1,4 bonds. There are also β-1,3 side chains present, as well as β-1,6 side chains. The β-1,6 side chain regions are where the protein structure is attached on PSK (either through a O- or N- glycosidic bond
Glycosidic bond
In chemistry, a glycosidic bond is a type of covalent bond that joins a carbohydrate molecule to another group, which may or may not be another carbohydrate....
).
See also
- Polysaccharide PeptidePolysaccharide PeptidePolysaccharide peptide is a protein-bound polysaccharide extracted from the edible mushroom Coriolus versicolor. PSP is currently in the animal-testing phase of research in many countries for use as an anti-tumor drug. It appears to work as a Biological Response Modifier, enhancing the body's own...
- Coriolus versicolor
- Medicinal mushroomsMedicinal mushroomsMedicinal mushrooms are mushrooms, or mushroom extracts, that are used or studied as possible treatments for diseases. Lentinula edodes , Grifola frondosa , Ganoderma lucidum , and Cordyceps, have a history of medicinal use spanning millennia in parts of Asia...
- MC-S
External links
- American Cancer Society's page for Trametes versicolor and Polysaccharide-K.
- Memorial Sloan-Kettering Cancer Center's page for Trametes versicolor and Polysaccharide-K.
- A "Detailed Scientific Review of Trametes versicolor and Polysaccharide-K" by the MD Anderson Cancer Center.
- Trametes versicolor and Polysaccharide-K information from Drugs.com.