The apoptotic effect of polysaccharides with specific molecular weight extracted from Inonotus obliquus on HT-29 colon cancer cells

Abstract

Background: Recently, natural products, particularly Inonotus obliquus (I. obliquus), have attracted lots of attention due to their effective anticancer effects with relatively low toxicity. Results: I. obliquus polysaccharides (IOP) with different molecular weights were obtained by filtering the aqueous extract through fractional membrane. IOP60b (10 kDa ≤ molecular weight ≤ 30 kDa) with the highest yield and inhibition ratio of HT-29 cancer cells was chosen to evaluate the apoptotic effect on HT-29 cancer cells. After treated with different concentrations of IOP60b, morphological changes including cell shrinkage and nuclear condensation and DNA fragmentation of HT-29 cancer cells were observed. In addition, the proportions of cells in early apoptosis and late apoptosis were significantly (p<0.05) increased in a dose-dependent manner. To further explore the underlying mechanism, RT-PCR and Western blotting were employed. Results indicated that both Bcl-2 family and Caspase family were involved in the regulation process of apoptosis and IOP60b induced cellular apoptosis via upregulation of Bax/Bcl-2 ratio and activation of Caspase-3.Conclusion: These data suggested that IOP60b could be a potential candidate for the clinical prevention and treatment of colorectal cancer.