Evaluation of polysaccharopeptide effects against C6 glioma in combinationwith radiation

Long-term control of high-grade brain tumors is rarely achieved with curren t therapeutic regimens. The major goal of this study was to determine wheth er polysaccharopeptide (PSP), a crude polysaccharide peptide extract derive d from Coriolus versicolor, a fungus, could enhance the effects of radiatio n against glioma cells in culture and in xenografted tumors in vivo. PSP si gnificantly augmented radiation-induced damage to C6 rat glioma cells in vi tro. Nude mice injected subcutaneously with the C6 cells were treated with PSP (injected intraperitoneally at 2 mg/injection) and radiation (2 Gy/frac tion, 8 Gy in total) using three different time-dose protocols. Tumor volum es were consistently smaller in all treated groups compared to the non-trea ted tumor-bearing controls except in one group which received PSP prior to tumor implantation. The administration of radiation alone resulted in the s lowest tumor progression, whereas PSP alone had no effect. Furthermore, PSP in combination with radiation treatment did not increase radiation efficac y. Natural killer cell, lymphocyte and granulocyte counts in blood and sple en were significantly higher in PSP-treated animals, demonstrating that PSP has protective effects on immunological function. Collectively, these resu lts warrant further investigation to determine if PSP can be effectively ut ilized to upregulate immune responsiveness in case of neoplasia and other d iseases in which immunosuppression is a prominent feature. Copyright (C) 20 01 S. Karger AG, Basel.