Study On The Anti-tumor Effect Of Dendrobium Huoshanense Polysaccharides On Colon Cancer-bearing Mice

Dendrobium huoshanense,which has been approved as a drug and food homologous material by Anhui local food safety standards,is a valuable Chinese herbal medicine recorded in Chinese materia medica,and polysaccharide(c DHPs)as its main active component has been proved to have obvious anti-tumor effects on lung cancer and gastric cancer-bearing mice.To further illustrate the wide spectrum anti-tumor effect of cDHPS on different tumors,colon cancer,whose incidence rate and mortality rate separately rank the third and the second of various tumors in the world,was chosen as a representative to construct CT26-WT colon cancer-bearing mice model and analyze tumor cell proliferation and apoptosis,immune response regulation and intestinal flora change in tumor-bearing mice in this study.The obtained results could lay the foundation for the further study of anti-tumor mechanism of cDHPS and provide theoretical basis for the application of cDHPS in delaying the occurrence and development of tumor.The main results obtained were shown as follows:(1)cDHPS could significantly inhibit tumor growth in tumor-bearing mice.Oral administration of cDHPS could effectively inhibit the increase of tumor volume and weight.With a continuous gavage at 400 mg/kg·d for 30 days,the inhibitory effect of cDHPS on tumor reached(62.14 ± 3.62)%.The analysis of HE staining,immunohistochemistry and TUNEL immunofluorescence showed that cDHPS could inhibit the growth of tumor by repressing the proliferation and angiogenesis of tumor tissues as well as promoting the apoptosis of tumor cells.(2)cDHPS could effectively enhance the anti-tumor immune function of tumor-bearing mice.The results of organ index showed that cDHPS could alleviate the damage of spleen,increase thymus index,and have the effects of enhancing immunity and protecting organs.The flow cytometry analysis of immune cells showed that the cDHPS could significantly inhibit the differentiation of regulatory T cells,and promote the proliferation of CD4+T cells,B cells,dendritic cells and macrophages in tumor,spleen and peripheral blood of tumor-bearing mice.The results of cytokine detection showed that cDHPS could rebalance the level of different immune cytokines in tumor microenvironment of tumorbearing mice to regulate the anti-tumor immune response.(3)cDHPS could obviously improve the intestinal microflora structure of tumorbearing mice.High-throughput 16 S r RNA sequencing of mouse feces showed that cDHPS could significantly increase the abundance and species diversity of intestinal flora in tumor-bearing mice.At the phylum level,cDHPS could up-regulate the abundance of Bacteroidetes and down-regulate the abundance of Proteobacteria as well as the ratio of Firmicutes to Bacteroidetes(F/B),which makes the flora structure closer to the normal group.At the genus level,cDHPS could down-regulate the relative abundance of pathogenic bacteria and opportunistic pathogens including Desulfovibrio,Bacteroides,and Helicobacter,up-regulate the relative abundance of probiotics and short chain fatty acid producing bacteria including Bacteroides＿S24-7＿group＿norank,Lactobacillus,Bifidobacterium,Ruminococcus＿1 and Ruminiclostridium＿9.In conclusion,cDHPS displayed an effective anti-tumor effect in CT26-WT colon cancer-bearing mice,and the responses of immune cells,immune cytokines and intestinal flora composition to cDHPS in cancer-bearing mice could play an important role in inhibiting the proliferation and angiogenesis of tumor tissues and stimulating the apoptosis of tumor cells.