Cell survival or apoptosis: rooperol's role as anticancer agent.

Nontoxic hypoxoside, isolated from Hypoxis, is converted to cytotoxic rooperol in the presence of beta-glucosidase. In this study, we investigated rooperol's mechanism of action. IC50 values of hypoxoside and rooperol were determined against the HeLa, HT-29, and MCF-7 cancer cell lines, and peripheral blood mononuclear cells. DNA cell cycle arrest occurred in late G1 and/or early S phases, associated with increased p21(Waf1/Cip1) levels. Apoptosis was shown by caspase-3 and/or caspase-7 activation, phosphatidylserine translocation, DNA fragmentation, cell blebbing, and apoptotic body formation. Increased phospho-Akt, phospho-Bcl-2, and p21(Waf1/Cip1) proteins, and cell size correspond to cell survival strategies (associated with endoreduplication).