Establishment Of Mouse Model Of Colorectal Cancer And Its Application In Drug Research

Berberine,a natural product from Chinese herbal medicine,has been proved to inhibit the proliferation of human colorectal cancer cells in vitro.In this study,two different kinds of animal models of colorectal cancer(CRC)were built and then applied to evaluate the in-vivo pharmacological effect of Berberine.The first one is orthotropic xenograft tumor model.In this model,HT29 cell line transfected with luciferase reporter gene was first subcutaneously transplanted to Balb/c nude mice.Tumor was harvested and cut into small pieces,then tissue block was transplanted to NODSCID mice by embedding it against the serosa at the beginning of ascending colon.Tumor growth rate was monitored periodically with living-image chemiluminescence detection.The tumor growth rate and tumor volumes in-situ were found to be lower in mice given Berberine than in control group,indicating that Berberine inhibited the growth of xenografts.Next,we verified the anti-cancer effect of Berberine in chemo-induced model of CRC in C57 mice.Azoxymethane combined with dextran sulfate sodium was used to induce colonic inflammation and tumor initiation,by which we built a stable,repeatable mice model with high biological similarity to human CRC.Through this model,we also proved that orally administrated Berberine can significantly inhibit the initiation and progression of CRC.Mice given Berberine,especially preventatively,would have much less tumor burden(number and volume)than in control group,suggesting that Berberine might have the potential to prevent tumorigenesis among people with high risk factors of CRC or the postoperative recurrence among CRC patients.Therapeutic administration of Berberine could also slower the progression of CRC and reduce tumor burden as well,even not so effective as preventive administration.We compared the gut flora structures of mice between CRC control group and Berberine treatment group,using 16S-rDNA sequencing and OTU clustering analysis,and found that Akkermansia muciniphila,a group of intestinal anaerobic bacteria,was apparently up-regulated by Berberine.Furthermore,Akkermansia muciniphila cultured in vitro was then gavaged to CRC mice alone or in combination with Berberine,to find out its role in the drug effect of Berberine.Results showed that tumor inhibition ratio of combination group was significantly higher than Berberine or A.muciniphila alone,and even higher than the sum of their individual effects,both in prevention and treatment group,which meant that drug combination had a synergistic effect.Although A.muciniphila failed to inhibit CRC when used alone,there is great possibilities that it bears an important part of Berberine's anti-cancer activity.