玉皇菇中一種新免疫調節蛋白之純化與其生理活性之研究

Abstract

菇類已成為受歡迎的抗腫瘤、抗病毒、抗菌、抗氧化和免疫調節劑的天然來源。Pleurotus citrinopileatusu別名玉皇菇為東方國家中常見的一種食用菇類,我們從其新鮮子實體分離出一種非凝集素的功能性醣蛋白(PCP-3A)並評估其免疫調節和抗腫瘤活性。電泳分析證實，PCP- 3A是一種由10個次單體所組成的醣蛋白，每個次單體大小約45 kDa。在體外培養細胞實驗發現，PCP- 3A能夠抑制U937增生且具有時間依存性。藉由流式細胞儀分析其抑制之機制，發現PCP-3A可藉由誘導U937細胞之S期停滯和細胞凋亡而抑制細胞增生。而在免疫調節活性方面， PCP-3A能刺激人類單核球細胞分泌細胞激素TNF-α、INF-γ、IL - 2和IL -10。此外，在抗發炎之活性作用上，PCP-3A能抑制經LPS誘導的RAW 264.7細胞之NO生成，分析PCP3 A對LPS誘導的RAW 264.7細胞中 iNOS和COX – 2之表現量，其中NO之減少和iNOS表現量之降低具有正相關性。

Mushrooms have become popular sources of natural antitumor, antiviral, antibacterial, antioxidative, and immunomodulatory agents. Golden oyster mushroom, Pleurotus citrinopileatus, is a common mushroom in oriental countries for human consumption. In this study, we isolated a non-lectin functional protein (PCP-3A) from the fresh fruiting body of this mushroom and investigated its immunomodulatory and antitumor activities. Electrophoresis demonstrated that PCP-3A is a glycoprotein composed of 10 subunits, each approximately 45.0 kDa in size. In vitro cell study showed that PCP-3A inhibits the proliferation of human tumor cell line U937 in a time-dependent manner. To elucidate the mechanism of growth inhibition, flow cytometry revealed that it is capable of inhibiting the growth of U937 cells by way of S phase arrest and apoptotic induction. In addition, evaluation of the immunomodulatory effect showed that PCP-3A stimulated the secretion of cytokines TNF-α, INF-γ, IL-2, and IL-10 from human peripheral blood mononuclear cells. The anti-inflammatory of PCP-3A was also evaluated. PCP-3A was found to effectively inhibit NO generation on LPS-Induced RAW 264.7 cells. To elucidate the mechanism of NO reduction, the effects of PCP3-A on LPS-induced iNOS and COX-2 expression in RAW 264.7 cells were examined.There is positive correlation between the inhibition on the generation of NO and the expression of inducible nitric oxide synthase in macrophage.