[Therapeutic effect and mechanism of sulfate polysaccharide of algae on lung cancer].

ABSTRACT

OBJECTIVE: To study the effect of sulfate polysaccharide of algae (SPA) on lung carcinoma and it's mechanism. METHODS: (1) C57BL/6 mice implanted with Lewis lung carcinoma were used as experimental animal model. The mice were randomly divided into a control group, SPA groups (3 groups) and a FT-207 group. After inoculation with Lewis lung carcinoma, the control group was treated with NS, the 3 SPA groups were treated with SPA 20 mg, 40 mg, and 80 mg/kg respectively, and the FT-207 group with FT-207 150 mg/kg for 10 days. The inhibiting activity of SPA on Lewis lung carcinoma was assayed, and proliferation of A549 tumor cells treated with SPA was detected by MTT assay. (2) New Zealand rabbits were randomly divided into a control group, a SPA 500 mg/kg group and a CTX 100 mg/kg group. Serum pharmacological method, and both in vivo and in vitro anti-tumor experiments were used in the study. After incubating A549 with SPA containing serum at different concentrations, the growth and apoptosis of cells, cell cycle, apoptosis rate and expression of apoptosis associated genes such as p53 and bcl-2 were detected by flow-cytometric assay. RESULTS: (1) SPA significantly inhibited the growth of implanted Lewis lung carcinoma in vivo and the effect had a dose dependent manner. The inhibitory rates of SPA on C57BL mice implanted Lewis lung carcinoma were 35.27% (P < 0.01), 48.29% (P < 0.01), and 65.41% (P < 0.01) respectively, which showed dose-dependent effects. SPA directly added to the culture medium neither induced A549 lung cancer cell apoptosis nor inhibited its proliferation in vitro. (2) SPA containing serum significantly induced A549 lung cancer cell apoptosis and inhibited its proliferation, with an increased expression of p53 and decreased expression of bcl-2 positive proteins, showing time and dose-dependent relationship. CONCLUSIONS: SPA possessed remarkable inhibitory activity against lung neoplasia in animal models and lung cancer cell strain. The anti tumor activity of SPA was considered to be derived from apoptosis induction, which might be associated with the increased expression of p53 and decreased expression of bcl-2 positive proteins.