Anti-tumor activity of polysaccharides extracted from Senecio scandens   Buch, -Ham root on hepatocellular carcinoma

Purpose: To optimize the extraction conditions of polysaccharides from the root of Senecio scandens Buch,-Ham. (PRS) and evaluate its anti-tumor effect on hepatocellular carcinoma.
Methods: Response surface methodology (RSM) applied with a Box-Behnken design (BBD, three levels and three factors) was employed to determine the effect of extraction time, number of extraction and ratio of water to raw material on the yield of PRS. The anti-tumor effect of PRS on A549, HL60, S180 and H22 cell lines was evaluated in vitro by 3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide (MTT) assay, while in vivo anti-tumor effect was evaluated in H22 tumor transplanted mice. Furthermore, expressions of proteins including caspase-3, caspase-9, Bcl-2 and Bax were determined by western blotting assay.
Results: The established BBD model was highly significant and the optimal conditions were: extraction time, 3.06 h; number of extractions, 2; and ratio of water to raw material, 16.17 mL/g. PRS showed significant inhibitory effect on H22 cells (IC₅₀ = 42.4 μg/mL), and significantly inhibited the growth of transplanted H22 tumors in mice at the doses of 20, 40 and 80 mg/kg (p < 0.05, p < 0.05 and p < 0.01, respectively). Treatment with PRS (20, 40 and 80 μg/mL) significantly up-regulated the expressions of Bax, caspase-3 and caspase-9 in H22 cells, whereas Bcl-2 protein was significantly down-regulated.
Conclusion: The results suggest that PRS possesses significant anti-tumor activity on H22 cell line in vitro and in vivo, and the mechanism may be closely related to the induction of mitochondria-mediated apoptosis.

Keywords
Senecio scandens; Polysaccharides; Hepatocellular carcinoma; Response surface methodology; Anti-tumor activity; Apoptosis