ANTITUMOR EFFECTS OF A REFINED POLYSACCHARIDE PEPTIDE FRACTION ISOLATED FROM CORIOLUS-VERSICOLOR - IN-VITRO AND IN-VIVO STUDIES

RPSP, a refined polysaccharide peptide fraction isolated by fast perfo rmance liquid chromatography (FPLC) from the crude powder of total pep tide-bound polysaccharides of cultivated Coriolus versicolor Cov-1 dos e-dependently inhibited the proliferation of a human hepatoma cell lin e (HEPG2). The effective dose causing 50% inhibition following 3-day e xposure to RPSP was 243 +/- 36 mu g/ml for HEPG2. However, little or n o inhibitory effects were detected in normal human foetal hepatocytes. On the other hand, in the pretreatment group, in which RPSP was admin istered i.p. for two weeks before sarcoma 180 inoculation in nude mice , the incidence of tumor growth was less (2 out of 5 mice) than that o f the control group (all 5 mice). The tumor size of the control group was about 3-5 times bigger than that of the pretreatment group. In tum or-bearing nude mice, 5 days after sarcoma 180 inoculation, i.v. admin istration of RPSP significantly suppressed the growth of tumor mass. T he inhibition rate was 93.6% on day 13. Furthermore, administration of RPSP did not cause any pathological lesions in vital organs of rabbit s such as heart, liver, spleen, lung and kidney, In conclusion, these results indicate that RPSP acts by directly suppressing tumor cell gro wth in vitro and the prevention of in vivo growth of tumor mass is pro bably mediated also via its immunomodulating effects.