Screening The Fermentation Products Of Lactobacillus Helveticus And Fungi With Anti-Colon Cancer Cell Activity And Preliminary Study On The Anti-tumor Mechanism

In order to screen and find microbial fermentation products with anti-tumor activity,we selected Lactobacillus helveticus and four edible and medicinal fungi,applying their fermentation products on colon cancer cell SW480 to investigate the anti-tumor effect of these fermentation products and preliminary study on the anti-tumor mechanism.In the first part of this thesis,we investigated the effect of L.helveticus extracellular polysaccharide on the cell viability of colon cancer cell SW480.After treatment with L.helveticus extracellular polysaccharide at different concentration for 12 and 24 hr,the cell viability of colon cancer cells SW480 did not have significantly changed?After treatment with L.helveticus extracellular polysaccharide at a concentration of 1mg/mL for 48 hr,the cell viability of colon cancer cells SW480 was significantly reduced to 80.5% of the control.When the treating concentration increased to 10mg/mL,the cell viability of SW480 was reduced to 72% of control after 12 hr,and to 33.5% of the control after 48 hr.This indicates that the L.helveticus extracellular polysaccharide can reduce the cell viability of colon cancer cells SW480,in time and concentration dependent manner.Secondly,we studied the effect of L.helveticus extracellular polysaccharide on apoptosis and migration of SW480.The results showed that the proportion of apoptosis in colon cancer cells SW480 was not significantly changed after treatment with 10mg/mL of extracellular polysaccharide for 48 hr.However,SW480 cells treated with 2.5 and 5mg/mL extracellular polysaccharide for 24 hr showed a significant decrease in migration ability compared with the control group.This indicates that the extracellular polysaccharide can not induce the apoptosis of colon cancer cell SW480,but it significantly inhibited the migration activity of SW480.In the second part of this thesis,we mainly studies anti-tumor effect of the fermentation products of Ganoderma lucidum,Pleurotus ostreatus,Irpex lacteus,and Schizophyllum commune cultured in Potato dextrose broth,with addition of 2% citrus sinensis osbeck powder,2% maize straw powder,2% sweet potato residue powder or not.Firstly,the effects of different fermentation products of four fungi on the cell viability of SW480 were studied by CCK8 experiment.It was found that the anti-tumor activity of thefermentation products of Schizophyllum commune was the strongest among the four fungi;and adding maize straw powder during fermentation can effectively enhance the anti-tumor activity of fungal fermentation products.We chose the fermentation products of Schizophyllum commune with maize straw powder to further study the mechanism of its anti-tumor activity on colon cancer cell SW480.By detecting with flow cytometry,we found that the fermentation products of Schizophyllum with maize straw powder could induce apoptosis of colon cancer cell SW480.The results of protein immunoblotting showed that Caspase3 and PARP protein were cleaved,further proving the effect of the fermentation products on apoptosis of colon cancer cell SW480.Next,in order to determine the specific pathway of apoptosis induced by the fermentation product of Schizophyllum with corn straw powder,we detected the mitochondrial membrane potential of colon cancer cell SW480 after fermentation product treatment,and found that the fermentation product significantly reduced the mitochondrial membrane potential and increased the ROS level in colon cancer cell SW480,indicating that the fermentation products could induce apoptosis of SW480 by activating mitochondria-mediated apoptosis pathway.In summary,this study found that L.helveticus extracellular polysaccharide can reduce the cell viability of colon cancer cell SW480 and inhibit its migration but fail to induce apoptosis.Among the four fungal fermentation products,the anti-tumor activity of the fermentation products of Schizophyllum commune is the strongest.and among the three different powder,the addition of 2% maize straw powder can effectively enhance the anti-tumor activity of different fungal fermentation products and found that the fermentation products of Schizophyllum commune with maize straw powder significantly reduced the mitochondrial membrane potential and increased the ROS level in colon cancer cell SW480,indicating that the fermentation products of Schizophyllum commune with maize straw powder could induce apoptosis of colon cancer cell SW480 by activating mitochondria-mediated apoptosis pathway.our study initially screened the fermentation product with anti-colon cancer cell SW480 activity,which laid the foundation for further research on separation of better anti-tumor active substances from this fermentation product.