The Effect Of Inulin,cellulose And Their Mixture On Liver Metastasis In Orthotopic Transplantation Mice With Colorectal Cancer

Objective: By establishing in orthotopic transplantation of colon cancer model,the effects of inulin,cellulose and their mixture on gut microbiota composition and expression of proteins related to epithelial-to-mesenchymal transition in BLAB/c mice were observed,and the effects and mechanisms of different dietary fibers on liver metastasis of colorectal cancer in mice were explored.Methods: Lentivirus-transfected CT-26-Luc cells were injected under the serous layer of the cecum of BALB/c male mice to establish a mouse model of in situ implantation of colorectal cancer.After 2 weeks of modeling,the tumor formation of mice cecum was monitored by imaging system,60 male mice were randomly divided into 4 groups according to body weight: model group(MOD,AIN-93 M diet),inulin group(INU,AIN-93 M diet +10%w/w inulin),cellulose group(CEL,AIN-93 M diet +10%w/w cellulose),mixed group(MIX,AIN-93 M diet+5%w/w inulin+5%w/w cellulose),15 mice in each group,the intervention lasted for 5 weeks.In addition,15 normal control group(NC)were set up and fed AIN-93 M diet continuously.During the intervention period,the body weight,food intake and survival of the mice were observed and recorded.After the intervention,the mice were executed,and the in situ tumor weight,liver weight,survival rate and liver metastasis rate of each group were calculated;HE staining was used to observe the pathological changes of colon and liver of mice;ELISA was used to detect the concentration of LPS and CTSK in mice serum;real-time quantitative PCR(RT-PCR)was used to detect the expression levels of TNF-α,TGF-β and IL-10 m RNA;Western blot was used to detect the expression levels of E-cadherin,N-cadherin,β-catenin,MMP-9 and VEG;The protein expression levels of E-cadherin,N-cadherin,β-catenin,MMP-9 and VEGF were detected by Western blot;the intestinal flora of mice in each group were compared by 16 S r RNA sequencing;the contents of short-chain fatty acids(SCFAs)in mice feces were detected by gas chromatography.Results: Compared with MOD group,inulin,cellulose and their mixture intake decreased tumor weight in situ,liver weight and liver metastasis area(P<0.05),and increased the survival rate of mice.Compared with NC group,the concentrations of LPS and CTSK in serum and the expression levels of TNF-α,TGF-β and IL-10 in liver of MOD group were significantly increased(P<0.05).Compared with MOD group,the concentrations of LPS and CTSK in serum and the expression levels of TNF-α,TGF-β and IL-10 in liver of mice in intervention groups were significantly decreased(P<0.05).Compared with INU group,the expression level of TGF-β in CEL and MIX groups was significantly increased(P<0.05).Compared with NC group,the expressions of β-catenin and epithelial marker E-cadherin in MOD group were significantly decreased(P<0.05),and the expression of VEGF was significantly increased(P<0.05).Compared with MOD group,the expression of E-cadherin in INU group and MIX group was significantly increased(P<0.05),the expression of β-catenin in INU group and CEL group was significantly increased(P<0.05),and the expression of N-cadherin in CEL group and MIX group was significantly decreased(P<0.05).Compared with NC group,the Chao 1 and Shanon indices of intestinal flora in MOD group were significantly decreased(P<0.05).Compared with MOD group,all the three interventions could increase the β diversity of intestinal microflora of modeling mice,and the microflora structure of mice was more similar to that of NC group(P<0.05).In addition,LEf Se analysis results showed that Bifidobacteriales were enriched in the intestinal tract of INU group,Lactobacillus was enriched in CEL group and Lachnospiraceae was enriched in MIX group.Compared with MOD group,fecal acetic acid,propionic acid,isobutyric acid and butyric acid contents in INU group were significantly increased(P<0.05),and fecal butyric acid content in MIX group was significantly increased(P<0.05).Spearman correlation analysis showed that the generation of SCFAs was positively correlated with the abundance of Bacteroides,Alloprevotella and other beneficial bacteria,while the generation of acetic acid and propionic acid was negatively correlated with the abundance of harmful bacteria Rodentibacter(Adjusted P<0.05).The abundance of Rodentibacter was positively correlated with IL-10 and CTSK contents,and the abundance of Escherichia-Shigella was positively correlated with tumor weight in situ(Adjusted P<0.05).Conclusion: Inulin,cellulose and their mixture could act to inhibit liver metastasis of colorectal cancer in mice,and the mechanism may be achieved by increasing the relative abundance of beneficial bacteria and decreasing the relative abundance of harmful bacteria,inhibiting the occurrence of inflammation,and blocking the epithelial mesenchymal transformation process of cancer cells.Among the 3 interventions,inulin was more effective in inhibiting colorectal cancer metastasis.