Shiitake (Lentinus edodes) mushrooms have been reported to have cancer-preventing properties. However, little research has been conducted verifying the antitumor activities of "mycochemicals" in shiitake mushrooms. In this study, potential roles of an ethyl acetate fraction from shiitake mushrooms were investigated by in vitro bioassays.
The activities of an ethyl acetate fraction were evaluated by [3-(4,5-dimethylthiazol-yl)-2,5-diphenyltetrazolium bromide] (MTT), apoptosis bioassay, cell cycle analysis, and Western blot analysis using two human breast carcinoma cell lines (MDA-MB-453 and MCF-7), one human nonmalignant breast epithelial cell line (MCF-10F), and two myeloma cell lines (RPMI-8226 and IM-9).
Concentration-dependent antiproliferative effects of the fraction were observed in all cell lines using the MTT assay. Approximately 50 mg/L concentration of the fraction induced apoptosis in 50% of the population of four human tumor cell lines and the fraction-induced apoptosis may have been mediated through the pro-apoptotic bax protein which was up-regulated. Cell cycle analysis revealed that the fraction induced cell cycle arrest by significant decrease of S phase, which was associated with the induction of cdk inhibitors p21 and the suppression of cdk4 and cyclin D1 activity. Compared to malignant tumor cells, nonmalignant cells were less sensitive to the fraction for the suppression of cell growth and regulation of bax, p21, cyclin D1, and cdk4 expression. A 51% antiproliferative effect occurred at the highest concentration of the fraction (800 mg/L).
These data suggest that inhibition of growth in tumor cells by "mycochemicals" in shiitake mushrooms may result from induction of apoptosis.
J Altern Complement Med. 2006 Mar;12(2):125-32.
Inhibition of human colon carcinoma development by lentinan from shiitake mushrooms (Lentinus edodes).
Lentinan was extracted from shiitake mushrooms (Lentinus edodes) via a new cost-effective procedure that resulted in high purity (88%) and yield. Unlike previous reports whereby the lentinan was given parenterally, in this study the emphasis was on the oral administration of lentinan. The goal is to document whether the efficacy of the antitumor property is still expressed through this route of administration.
Initial study on the action of lentinan was conducted using murine lymphoma (K36) cells in a AKR mouse model. Further investigation on the effectiveness of the extracted lentinan was then performed using human colon-carcinoma cell lines in mice. Six established human colon-carcinoma cell lines segregated into three groups of different degrees of differentiation were used in this study. One group was not fed (control) and the second group was prefed with lentinan for 7 days prior to inoculations with the cancer cells. The size of the tumors that developed was rated after 1 month.
Significant regression in tumor formation was observed in prefed mice compared to control (unfed) mice when K36 or human colon-carcinoma cells were used. Significant reductions in the size of the tumors were observed in mice prefed with lentinan. Follow-up investigation proceeded with the use of nude mice (athymic). Lymphocytes extracted from AKR mice prefed with lentinan for 7 days were inoculated into the nude mice. This was then followed by inoculation of the human colon-carcinoma cell lines into these mice. Much smaller tumors were formed in nude mice inoculated with lymphocytes, in contrast to the larger tumor formed in nude mice without lymphocytes inoculation.
This study showed that the antitumor property of lentinan was maintained with oral administration. In addition, "primed" lymphocytes, when given passively to immunodeficient mice, were able to retard the development of tumors in these mice.
1Department of Microbiology, National University of Singapore, Singapore. email@example.com
J Altern Complement Med. 2002 Oct;8(5):581-9.
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