Immunostimulatory And Antiproliferative Effects Of Kenyan Trametes Versicolor Mushroom Extracts On Selected Cancer And Normal Cell Lines

Abstract

Cancer is a major public health burden in both developed and developing countries. The current conventional cancer therapies like chemotherapy are expensive and inaccessible to many cancer patients. Medicinal mushrooms are becoming important as an alternative source of immune modulation and anticancer agents. This study examined the in vitro antiproliferative activity of an aqueous extract of a Kenyan Trametes versicolor (TV) mushroom on breast cancer (4T1), prostate cancer (DU145), hepatocellular carcinoma (HCC), rat normal intestinal epithelial cells (IEC-6) and African green monkey normal kidney (vero) cell lines using MTT assay. Polysaccharide extract of TV was used to evaluate the expression levels of IL-7 mRNA on IEC-6 cells using one step RT-PCR. Statistical methods (student T-test and ANOVA) were used to analyze the significance of antiproliferative activity. Double delta CT analysis was used to evaluate IL-7 mRNA expression fold change relative to GAPDH, a house keeping gene. Two-sample independent T-test was used to assess the significance in IL-7 mRNA expression at 95% confidence interval. The results demonstrated that the TV aqueous extract at 1.37 μg/ml to 1000 μg/ml dose-dependently inhibited the proliferation of DU145 and 4T1cell lines with IC50 values: DU145 (71.2 μg/ml) and 4T1 (188.5 μg/ml). The aqueous extract however did not exert any significant antiproliferative effect on HCC, IEC-6 and vero cell lines (IC50 ˃1000 μg/ml) when compared with an anticancer drug, tamoxifen (P ≤ 0.05). There was a slight increase on the expression of IL-7 mRNA on IEC-6 cells treated with TV extract, with a fold change of 0.17. The increase in expression of IL-7 mRNA was found to be significant when the mean CT value of the treated cells was compared to that of the untreated cells with a P value of 0.035. The antiproliferative activity of the Kenyan TV aqueous extract suggests selective inhibition of cancerous cells while its polysaccharides slightly up regulates IL-7 mRNA expression on IEC-6 cells. Further studies with purified bioactive compounds of Kenyan T. versicolor to assess possible cell death mechanism is recommended. A study on the immunomodulatory potential of purified T. versicolor polysaccharides supplemented with other herbals is also recommended.