INHIBITORY EFFECT OF A TRADITIONAL CHINESE MEDICINE, JUZEN-TAIHO-TO, ON PROGRESSIVE GROWTH OF WEAKLY MALIGNANT CLONE CELLS DERIVED FROM MURINE FIBROSARCOMA

We have investigated the inhibitory effect of oral administration of J uzen-taiho-to, a Kampo (Chinese herbal) medicine, on progressive growt h of a mouse fibrosarcoma. spontaneously regressive QR-32 tumor cells were able to grow progressively in vivo when coimplanted s.c. with a f oreign body, gelatin sponge, whereas QR-32 cells alone gradually grew for over 15 days after inoculation and thereafter regressed for up to 25 days. Oral administration of Juzen-taiho-to (40 mg/day/mouse) for 7 days after inoculation of QR-32 cells with gelatin sponge resulted in significant inhibition of tumor growth and prolongation of the surviv al of the tumor-bearing mice, This growth-inhibitory effect of Juzen-t aiho-to observed on day 25 was dose-dependent over the dose range from 4 to 40 mg/day. Treatment with Juzen-taiho-to for 7 days before tumor inoculation with gelatin sponge also significantly suppressed tumor g rowth examined on day 25, as did the administration of bismuth subnitr ate, which is well known to induce metallothionein, an antioxidant. On the other hand, inoculation of progressed tumor cells (QRsP) resulted in growth without gelatin sponge, leading to death in syngeneic mice, Administration of Juzen-taiho-to for 7 days after inoculation of QRsP cells resulted in a decrease of the tumor growth and prolongation of the survival of mice, but the effect was less than that on the growth of QR-32 regressor tumor after coimplantation with gelatin sponge. The se results suggest that the inhibitory effect of Juzen-taiho-to is par tly associated with prevention of gelatin sponge-elicited progressive growth, probably mediated by endogenous factors including antioxidant substances, in addition to the augmentation of host-mediated antitumor activity.