Background of Coriolus Versicolor (Turkey Tail) Mushroom
Coriolus versicolor is a mushroom used in traditional Asian herbal remedies. Two substances extracted from the mushroom, polysaccharide K (PSK) and polysaccharide-peptide (PSP), are being studied as possible complementary cancer treatments. Verisicolor polysaccharide (VPS), another extract from the mushroom that is sold as a dietary supplement in the United States, is also being studied.
Coriolus versicolor has been a component of traditional Asian medicine for centuries. In the 1980s, the Japanese government approved the use of PSK for treating several types of cancer. In Japan, PSK is a best-selling anti-cancer drug where it is currently used as a cancer treatment along with surgery, chemotherapy, and radiation therapy. PSP was discovered more recently and has been studied mainly in China.
Coriolus versicolor is thought to be a biological response modifier. The proteoglycan constituents are responsible for its immunostimulant and anticancer activities.
RESEARCH: Many different mechanisms of action have been proposed for the activity of these components. PSK has been found to induce cytokine expression in human peripheral blood mononuclear cells in vitro. In another studies, PSP, as well as Coriolus extract, selectively induced apoptosis of human promyelocytic leukemia HL-60 cells42,43. It also increased apoptotic cell death in cells that had been treated with the chemotherapeutic agent, camptothecin. In these cells, PSP reduced cellular proliferation, inhibited cell progression through both the S and G2 phases of DNA replication, reduced 3H – thymidine uptake, and prolonged DNA synthesis time44. An additional in vitro study showed that a medicinal mushroom blend that included Coriolus Versicolor inhibited cell proliferation and induced cell cycle arrest at the G2/M phase in the invasive human breast cancer cell line MDA-MB-23145. DNA-microarray analysis indicated that the mushroom extract inhibited the expression of cell cycle regulatory genes and suppressed metastatic behavior through the inhibition of cell adhesion, cell migration, and cell invasion . The inhibition of metastatic behavior was linked to the suppression of urokinase plasminogen activator (uPA)46. PSP has also been shown to inhibit the interaction between HIV-1 gp120 and CD4 receptor, HIV-1 transcriptase activity, and glycohydrolase enzyme activity associated with viral glycosylation47.
Researchers have found that PSK, one of the substances that can be extracted from Coriolus versicolor, has several anti-cancer properties. In some animal studies, it slows the spread of cancer cells. PSK also appears to have some immune system–boosting properties in people undergoing chemotherapy and may lessen some side effects of chemotherapy and radiation therapy48. PSK is also believed to be a strong anti-oxidant, a compound that blocks the action of free radicals, activated oxygen molecules that can damage cells49.
More than 2 dozen human studies of PSK have been reviewed by experts at the University of Texas MD Anderson Cancer Center. Almost all of these studies were done in Japan and focused on cancer of the esophagus, stomach, colon, or breast. Most of them found that people with cancer were helped by PSK. People who received PSK with other treatments, such as surgery, chemotherapy, or radiation therapy, generally had longer periods of time without disease and had increased survival rates compared with patients who received only standard treatment. Side effects from PSK in these studies were very mild. Smaller studies have suggested PSK may not be as effective against liver cancer or leukemia50-53.
