The ethyl acetate extract of Phellinus linteus grown on germinated brown rice induces G_0/G_1 cell cycle arrest and apoptosis in human colon carcinoma HT29 cells

摘要

It is well known that Phellinus linteus has a variety of biological functions, such as antitumor and immunomodulating activities. In our previous studies, we developed a P. linteus grown on germinated brown rice (PBR) and found that organic solvent extracts of PBR possessed immunomodulating activity to regulate a balance of cytokine network in mice. The components of PBR are ergosterol peroxide, γ-aminobutyric acid (GABA) and β-glucan. In this study, we demonstrate that an organic solvent extract of P. linteus grown on PBR induced apoptotic cell death through the induction of G_0/G _1 arrest of cell cycle and the apoptosis via DNA fragmentation in human colon carcinoma HT-29 cells. Cell death induced by the extract of P. linteus grown on PBR was shown to be associated with the upregulation of p21~(CIP1/WAF1), the downregulation of cyclin D1, anti-apoptotic protein, Bcl-2, the release of cytochrome c, and the activation of caspase-9, caspase-3 and caspase-8. This study suggests that the ethyl acetate extract of P. linteus grown on PBR induces apoptosis accompanied by cell cycle arrest at G_0/G_1 phase and regulates apoptosis-regulatory proteins, which may be applicable to anticancer therapy.