Inhibition of colon cancer cells by Ganoderma lucidum triterpenes.

5472 Medicinal mushroom Ganoderma lucidum (Reishi, Lingzhi) has been used in the traditional Chinese medicine for more then two thousand years. Our previous studies have shown that Ganoderma lucidum extract(GLE), which contains 13% of polysaccharides (GLP) and 6% of triterpenes (GLT), is able to inhibit the proliferation, angiogenesis and invasiveness of breast and prostate cancer cells. In the present study we evaluated and correlated in vivo effects of GLT with cells growing under two- and three-dimensional (2D, 3D) cell culture conditions in vitro. Therefore, GLT markedly suppressed tumor growth in xenograft model of human colon cancer HT-29 cells injected into nude mice and inhibited proliferation of HT-29 cells in vitro. This effect was associated with the down-regulation of expression of Ki-67 and cyclin D1 in colon tumors, and cell cycle arrest of HT-29 cells at the G0/G1 phase. In addition, GLT down-regulated expression of cdk4 and suppressed phosphorylation of AKT. Furthermore, GLT induced apoptosis in colon tumors and colon cancer cells and inhibited β-catenin and NF-κB. In summary, our data suggest that mushroom triterpenoids, particularly GLT, could modulate intracellular signaling, which will eventually lead to the inhibition of growth and induction of apoptosis of colon cancer cells in vitro and in vivo. Further studies are necessary to evaluate this mushroom extract for the adjuvant or nutritional preventive or therapeutic interventions against colon cancer.