Antitumor effects of the partially purified polysaccharides from Antrodia camphorata and the mechanism of its action

Antrodia camphorata is a popular folk medicine that has attracted great attention due to its fame for antitumor activity against cancer. However, there is little information available about its action. In the present study, we purified a unique polysaccharide component from A. camphorata mycelia (AC-PS) and found that it has pronounced anti-tumor effects on both in vitro and in vivo model. Our results showed that AC-PS alone did not show any direct cytotoxic effect to human leukemic U937 cells, even at high concentration (200 microg/ml). However, it could inhibit the proliferation of U937 cells via activation of mononuclear cells (MNCs). Treatment of U937 cells with AC-PS-stimulated-MNC-CM could significantly inhibit its proliferation with 55.3% growth inhibition rate. The in vitro antitumor activity was substantiated by the in vivo therapeutical study of AC-PS in sarcoma 180-bearing mice. Intraperitoneal and oral administration of AC-PS, 100 and 200 mg/kg significantly suppressed the tumor growth with the inhibition rate of 69.1% and 58.8%, respectively. In vivo studies also showed that several immunoparameters, such as the spontaneous proliferation of spleen cells, after AC-PS administration, were two-fold higher than in control mice. Furthermore, the cytolytic activity of spleen cells also increased from 9.8 +/- 1.1% in control mice to 34.2 +/- 5.5% and 48.2 +/- 2.5%, after oral and intraperitoneal treatment, respectively. Besides, the mice serum interleukin-12 levels increased significantly by AC-PS treatment. Considering all these results, it is suggested that AC-PS elicit its anti-tumor effect by promoting a Th1-dominant state and killer activities.