Abstract
Effect of egg lectin from Rana japonica (RJ-lectin) on the growth of Ehrlich solid tumor was examined in male ddY mice, using the temporary circulation-stop method as an in vitro model. Lectin was injected intravenously 24 hr after inoculation of Ehrlich ascites carcinoma (1×106 cells) into the right thigh. The upper thigh was tightly ligated to stop blood circulation, and the animals were kept without movement with warming of the leg at 37° for 30 min. The antitumor activity was estimated by weihing the solid tumor on the 10th day after cell inoculation. Intravenous administration of RJ-lectin in the temporary circulation-stop method more strongly suppressed the tumor growth than by intravenous injection of the lectin without any treatment. The inhibitory action of RJ-lectin in the temporary circulation-stop method depended on the number of administrations. The inhibition rate of the lectin at 10 or 20 mg/kg (three intravenous administrations) was 93 and 77%, respectively. In this method the lectin may easily contact with tumor cell as observed in vitro and is able to react with the cells directly for a long time. It is suggested that RJ-lectin suppresses the tumor growth by direct cytotoxic effect on tumor cells.
