Cytotoxic effect of Cuscuta reflexa Roxb. and induction of apoptosis in human promyelocytic leukemia HL-60 cells

The anticancer potential of Cuscuta reflexa (whole plant extract), a holoparasitic plant collected from its host plant Euphorbia royleana was evaluated by testing its in vitro cytotoxicity and induction of cell death by apoptosis. Among three extracts (95% alcoholic, 50% hydro-alcoholic and aqueous extracts) and four fractions (n-hexane, chloroform, n-butanol and water) of alcoholic extract, the 95% alcoholic extract (A001) and its chloroform fraction (F002) showed significant cytotoxic activity human cancer cell lines. Both A001 and F002 inhibited cell proliferation and showed dose-dependent cytotoxicity against cervix (HeLa), prostate (DU-145), promyelocytic leukemia (HL-60), colon (50273) and ovary (OVCAR 5) human cancer cell lines. Both A001 and F002 induced apoptosis in HL-60 (human promyelocytic leukemia) cell line, as revealed by several biological end points viz., DNA ladder formation, annexin-V-FITC binding, cell cycle analysis and caspases induction. The F002 showed better activity than A001 by inducing apoptotic bodies formation, apoptotic DNA fragmentation, enhanced annexin-V-FITC binding of the cells, increase of G2/M phase cell cycle and induction of caspase-9,-8 and-3 activities, indicating the involvement of both intrinsic and extrinsic pathways of apoptosis. The results suggested that both A001 and F002 induced apoptosis through both mitochondrial-dependent and independent pathway in HL-60 cells. Thus, apoptotic effect of F002 against HL-60 cells suggests its potential in development as an anticancer drug.