OBJECTIVETo study glycyrrhizin's anticancer effect and its mechanism.

METHODS3-methylcholanthrene were injected into mice's submandibular glands to induce tumor, then transplanted the tumor pieces (1 mm3) to mice. The transplanted tumors were measured, and flow cytometry analysis and cytomorphology observation were conducted.

RESULTSGlycyrrhizin (GL) inhibited the transplanted mandibular gland fibro-sarcoma of mice and the suitable GL dose for inhibiting fibrosarcoma of mice was 1.61 mg per 20 g weight. The GL dose below 3.22 mg per 20 g weight didn't produce remarkable toxicity and side effects. GL induced cytomorphological changes of tumor cells and enhanced immunosuppression of macrophage on fibrosarcoma. The result of flow cytometry showed that tumor cell counts of GL1 and GL2 groups increased remarkably in DNA synthetic prophase, and decreased in DNA synthetic phase.

CONCLUSIONGL can inhibit transplanted mandibular gland fibro-sarcoma of mice. The anticancer mechanism of GL may be acting on related enzymes with phagocytosis. The result of flow cytometry showed that the shift of fibrosarcoma cells from G1 phase to S phase was blocked. This suggests that the anticancer action of GL is related to its inhibition of ribonucleotide reductase, a rate-limiting enzyme in DNA synthesis.