| Objective: Breast cancer is the most frequently diagnosed cancer worldwide and one of the leading causes of cancer deaths in women.At present,the clinical treatment of breast cancer is still mainly surgery,and combined with chemical drug treatment(chemotherapy)and radiotherapy for comprehensive treatment,of which chemical drug treatment plays an important role in the treatment of breast cancer.However,chemotherapy has a significant toxic effect on normal cells,and many healthy tissues are affected,with potentially fatal side effects,which can sometimes lead to lifelong illness.These shortcomings make it urgent for us to develop alternative treatment /management strategies with fewer side effects.In recent years,as a natural source of marine sulfated polysaccharides,fucoidan has attracted great attention from many scientists and has become a hot spot in the research of marine natural medicine.More and more evidence has shown that fucoidan has various biological functions such as anti-tumor,anti-oxidation,anti-coagulation,and immune regulation,and resists the toxic effects associated with radiotherapy and chemotherapy.However,the specific mechanism by which fucoidan inhibits the growth of tumor cells needs further study.Therefore,in this study,we observed the effect of fucoidan on the activity of human breast cancer cells MDA-MB-231 and MCF-7,and further studied the growth inhibitory effect of fucoidan on human breast cancer cells based on autophagy At the same time,the effect of fucoidan on the chemotherapy sensitivity of human breast cancer cells was explored,which may develop a new effective and low-toxic natural drug pathway for future clinical treatment of breast cancer.Methods: The effects of fucoidan MDA-MB-231?MCF-7,on human breast cancer cell viability were detected by MTT method;The effects of fucoidan on human breast cancer cell apoptosis were detected by flow cytometry;The changes of autophagy index LC3BII/LC3 BI and autophagy substrate p62 protein expression were detected;The changes of autophagosome and protein expression were observed by fucoidan combined with autophagy inhibitor;the ultrastructure of autophagy was observed by transmission electron microscope(TEM);And the changes of autophagy flux in different experimental groups were observed by mCherry-EGFP-LC3 transfection.Effects of fucoidan on chemosensitivity of human breast cancer cells were studied by flow cytometry and MTT cell viability of human breast cancer cells.Results: The growth of human breast cancer cells was significantly inhibited by fucoidan in a certain concentration range,and the cell viability decreased with increasing fucoidan concentration in a dose-dependent manner(P<0.05 or P<0.01 or P<0.001).Fucoidan can promote the apoptosis of two kinds of human breast cancer cells,and the apoptosis rate will increase with the increase of Fucoidan concentration(P<0.05 or P<0.01 or P<0.001).Flow cytometric analysis showed that the apoptosis rate of MDA-MB-231 cells was 12.1%,18%,23.3% and 35.8% in blank control group and fucoidan(100 ?g/mL?200 ?g/mL?400 ?g/mL)group.MCF-7 apoptosis rates were 5.7%,8.5%,10.5% and 13.8%,respectively.The apoptosis rate of MDA-MB-231 cells at the same concentration was higher than that of MCF-7(TEM).The results showed that there were more vesicle-like structures and autophagosomes in the cells of fucoidan group,and the autophagosome structure formed by fusion with lysosome was more obvious than that of control group.The LC3 of lysosome co-dyeing in brown algal gum group was more dot-like than that in blank control group.The results of Western blot experiment showed that the expression of LC3 BII in brown algal gum group was more and less than that in blank control group(P<0.05 or P<0.01 or P<0.001).The combination of fucoidan and adriamycin and cisplatin can enhance the sensitivity of human breast cancer cells to the two chemotherapeutic agents,and make the cell viability decrease significantly and the apoptosis rate increase(P<0.05 or P<0.01 or P<0.001).Conclusion: Experiments showed that fucoidan inhibited the growth of human breast cancer cells and promoted apoptosis.Based on autophagy further studies found that fucoidan inhibited the growth of human breast cancer cells by inducing increased autophagy formation and enhanced autophagy tide.At the same time,we also found that when fucoidan was combined with adriamycin and cisplatin,it could enhance the sensitivity of human breast cancer cells to the two chemotherapeutic agents and increase the apoptosis rate.This study provides a theoretical basis for further elucidating the mechanism of fucoidan in inhibiting the growth of human breast cancer cells and finding an effective way to enhance the chemosensitivity of human breast cancer cells. |
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