P0159 Bidens pilosa extract induces apoptosis through up-regulation of death receptor 5 in human colon carcinoma cell lines

Background Bidens pilosa Linn. var. radiata is a tropical weed widely present in tropical and subtropical regions, including Miyako Island, Okinawa, Japan. The whole plant or its leaves and stem are used in various folk medicines and as a popular ingredient in herbal tea for its anti-inflammatory, anti-septic, liver-protective, blood-pressure lowering, and hypoglycaemic effects. There are no reports of the effects of B. pilosa on human colorectal cancer cells. Methods We investigated the effects of B pilosa on the human carcinoma cell lines HCT116 and Caco-2. The former has wild-type p53, the latter has mutant p53. B pilosa was provided as an extract powder from Musashi Immune laboratory Co. (Miyako Island, Okinawa, Japan). Findings B pilosa (0.25, 0.5, and 1 mg/ml in medium) demonstrated dose-dependent growth inhibition on both cell lines, assessed by WST-8 assay (Nacalai Tesque, Kyoto, Japan). B pilosa induced apoptosis in both HCT116 and Caco-2 cell lines, assessed by DNA ladder. In addition, a cleaved caspase-8 was expressed in both cell lines, as assessed by western blot. In both cell lines, in spite of the p53-genetic status, B pilosa also increased the expression death receptor 5 (DR5), a TRAIL receptor that activates caspase-8, leading directly to the activation of caspase-3. Interpretation Our results suggest that B pilosa has the potential to prevent or treat for colon cancers through induction of apoptosis by a p53-independent pathway.