Antitumor Effects Of Fucoidan And The Related Mechanism In Vitro And In Vivo

BACKGROUND & OBJECTIVE:Fucoidan is a sulfated polysaccharide derived from brown algae that has been reported to perform multiple biological activities, including antitumor activity. Fucoidan could inhibit the growth of tumors, but the mechanism remains unclear. This study aimed to explore the antitumor effects and the related mechanism of fucoidan in vitro and in vivo with mouse breast cancer cell line 4T1 as target cell.METHODS:In vitro, fluorescent staining, flow cytometry, RT-PCR and Western blot were performed to analyze the cell cycle and apoptosis of mouse breast cancer 4T1 cells after treatment of fucoidan at different concentrations (0,50,100,200μg/ml). In vivo, therapy experiments were conducted on Babl/c mice bearing breast cancer. The tumor volume and weight were measured. The number of apoptotic cells in tumor tissues was assessed by TUNEL immunostaining. Western blot were used to detect the expression of Bcl-2, Bax, and Survivin in excised tumors. Immunohistochemical assays were used to detect the expression of Wnt/β-catenin signaling agents in tissues.RESULTS:When treated with fucoidan for 48h,4T1 cells showed typical apoptotic morphologic changes including chromatin condensation and DNA fragment. Along with the increase of fucoidan concentration, Bcl-2 expression was decreased, Bax expression was increased, and the ratio of Bcl-2 to Bax was significantly decreased (P<0.05). The expression of Survivin in 4T1 Cells was decreased when treated with fucoidan (P<0.05). Mitochondrial transmembrane potential was decreased and cytosyl cyt-C proteins increased in 4T1 cells after 48 h treatment of fucoidan detected by Western blot. When treated with fucoidan (50,100,200μg/ml) for 48 h, the activated Caspase-3 in 4T1 cells were significantly higher than that in control 4T1 cells (P<0.05).Moreover, the expression of VEGF was decreased when treated with fucoidan. In addition, the proportion of 4T1 cells at G1 phase was significantly increased with an apparent G1 phase arrest when treated with fucoidan (50,100,200μg/ml) for 48 h. In the progress of cell cycle arrest induced by fucoidan, the expression of B-catenin, cyclin-D1 and phosphorylated CDK4 were down-regulated (P<0.05).Intraperitoneal injection of fucoidan in subcutaneous breast cancer models reduced the tumor volume, induced apoptosis, inhibited angiogenesis in tumor tissue and decreased pulmonary metastases.CONCLUSION:Fucoidan could induce apoptosis and G1 phase arrest in 4T1 cells, possibly by decreasing the expression of Bcl-2/Bax and Survivin, activating Caspase-3, down-regulating the expression of B-catenin, cyclin-D1 and phosphorylated CDK4. Fucoidan also could inhibit tumor angiogenesis by down-regulating the expression of VEGF. These findings indicate that crude fucoidans inhibited mouse breast cancer growth in vitro and in vivo.These data suggest that fucoidan may serve as a potential therapeutic agent for breast cancer.