Protodioscin (NSC-698 796): Its spectrum of cytotoxicity against sixty human cancer cell lines in an anticancer drug screen panel

Protodioscin (NSC-698796) is a furostanol saponin isolated from the rhizome of Dioscorea collettii var. hypoglauca (Dioscoreaceae), a Chinese herbal remedy for the treatment of cervical carcinoma, carcinoma of urinary bladder and renal tumor for centuries. To systematically evaluate its potential anticancer activity, protodioscin was tested for cytotoxicity in vitro against 60 human cancer cell lines in the NCI's (National Cancer Institute, USA) anticancer drug screen. As a result, protodioscin was cytotoxic against most cell lines from leukemia and solid tumors in the NCI's human cancer panel, especially selectively against one leukemia line (MOLT-4), one NSCLC line (A549/ATCC), two colon cancer lines (HCT-116 and SW-620), one CNS cancer line (SNB-75), one melanoma line (LOX IMVI), and one renal cancer line (7860) with GI(50) less than or equal to 2.0 muM. In the general view of mean graphs, leukemia, colon cancer and prostate cancer are the most sensitive subpanels, while ovarian cancer is the least sensitive subpanel. Based on an analysis of COMPARE computer program with protodioscin as a seed compound, no compounds in the NCI's anticancer drug screen database have cytotoxicity patterns (mean graphs) similar to those of protodioscin, indicating that a potential novel mechanism of anticancer action is involved.