The Therapy And Prevention Effect Of Monotropein On The Colorectal Cancer And Its Mechanisms

Colorectal Cancer(CRC),a multi-factor-induced malignant tumor of digestive tract with the 3th highest morbidity and 4th highest mortality,leading cause of cancer-related death worldwide.Usually,colitis-associated cancer(CAC)more occured with the prolongation of the course of inflammatory bowel disease(IBD).In recent years,many scientists make their research focus on preventing the "inflammation-cancer"transformation and clarifying their mechanism.Nowadays,surgical treatment supplemented with chemotherapy is the basic treatment method for CRC.However,conventional chemotherapeutic drugs such as 5-FU and oxaliplatin has been known that could produced side-effects,and easy to develop resistance.In conclusion,finding more efficient and lower toxic natural anti-tumor drugs is necessary.Morinda officinalis,one of the traditional chinese medicine,with significant anti-inflammatory effect and certain improvement produce on DSS-induced colitis mice,because of the major iridoid component,Monotropein.However,the effect of Monotropein on CRC has not been reported.ObjectiveThe main purpose of this study is to evaluate the preventive and therapeutic effects of Monotropein on three well-established animals models of colorectal Cancer.Meanwhile,the effects of Monotropein on proliferation and invasion of human colon carcinoma cells were investigated.We further explore the potential mechanism of this molecule.Methods1.Effect of Monotropein on AOM/DSS induced colon cancer mice.To induce colitis-associated cancer(CAC),except for animals in control group,mice were injected intraperitoneally(i.p.)with 10 mg/kg of AOM followed by 3 cycles of 2%DSS.80 mice were randomly divided into 5 groups:control group,AOM/DSS group,positive group(a single dose(100mg/kg)of Mesalazine,5-ASA),the remaining two groups were orally treated with monotropein,at the doses of 2 and 8 mg/kg/day.Body weight,rectal bleeding,stool consistency,food and water intake in all mice were recorded daily and the disease activity index(DAI)was calculated.Intestinal permeability was measured 10 days before the end of the experiment by using FITC dextran.The length,thickness,tumor size,tumor numbers of colon were recorded.The pathological examination of the colon were observed.The levels of interleukin-6(IL-6),interleukin-10(IL-10),interleukin-1β(IL-1β)in the colon tissues were detected.The levels of VD3 and PG-E2 in the serum and colon tissues were detected.The level of VDR in colon tumors and tumor-adjacent tissue were determined by immunohistochemistry and immunofluorescence.2.Effect of Monotropein on proliferation and invasion of human colon carcinoma cells.The inhibition ratio of HCT-116,HCT-8 and Caco-2 cell lines were detected by MTT assay with different drug concentration and different co-incubating time.Through the cell scratch test,we examined the impact of Monotropein on colon cancer cell migration.3.Effects of Monotropein on growth of human colonic carcinoma xenograft tumor in nude mice.Human colon carcinoma cells(HCT-116 or HCT-8)transplanted subcutaneously in nude mice model was established,then divided into 2 groups:control groups and Monotropein groups.Tumor volume and body weight of mice were measured at regular time-intervals.Mice were sacrificed at the end of the experiment,the tumor was removed and weighted to calculate tumor inhibition rate.The pathological examination of the tumor were observed.The levels of VD3 and PGE2 in the serum and colon tissues were detected.The levels of VDR in tumors were determined by immunohistochemistry and immunofluorescence.Result1.Monotropein prevents inflammation response and tumorigenesis in AOM/DSS-induced colon cancer model.The body weight of the mice in treatment groups decreased slowly and DAI increased slowly following exposure to 2%DSS,moreover,body weight and DAI of mice in treatment groups showed more quickly recovery while being maintained on water than mice in AOM-DSS group.The colon length of AOM/DSS-treated mice was significantly shorter(P<0.001)and colon sickness was significantly sicker(P<0.001)than that of the control mice.Nevertheless,5-ASA or Mo treatment prevented the shortening and thickening of colon caused by AOM/DSS.Furthermore,as compared with AOM-DSS group,mice in Mo-treated groups showed fewer and smaller tumors in AOM-DSS inducedmodel.Moreover,Mo-treated groups improved spleen enlargement cansed by AOM-DSS and positive group showed no significant differences.Histological analysis revealed crypt destruction and large adenocarcinomas in AOM/DSS induced mice,Mo displayed a significant improvement of these pathological changes in a dose dependent manner.As our data shown,the expression levels of IL-6,IL-1β and PGE2 in AOM/DSS treatment group were significantly higher than other groups,and Mo also could improve the increase of IL-10 caused by AOM/DSS.Furthermore,the intestinal permeability in Mo treatment groups were remarkably lower than that in the AOM/DSS group(P<0.01).As compared with normal group,AOM-DSS group showed less expression of VDR(P>0.05),and Mo could improve the reduction of VDR expression caused by AOM/DSS in a dose dependent manner(P<0.01,P<0.05).These data showed that monotropein could prevent inflammation response and tumorigenesis in AOM/DSS induced colon cancer mice via regulating VDR signals.2.Effect of monotropein on the proliferation and migration of human coloncarcinoma cells.The results showed that,compared with the control group,proper monotropein significantly inhibit the growth of colon cancer cells at 24h and 48h without time and dose-dependent manner.There was no notable difference in the Caco2 cell migration between the monotropein and NC groups(P>0.05).Compared with the NC groups,HCT-116 and HCT-8 cells migration capacity underwent a significant decrease in the monotropein group at 24h.3.Inhibitory effect of monotropein on tumor growth in nude mice bearing subcutaneo us xenograft human colonic carcinoma.The results in vivo showed that monotropein significantly increased body weight and apparently inhibit the growth of mice bearing HCT-116 or HCT-8,the inhibitory rates were 39.4%and 28.6%respectively.Compared with control group,the levels of PGE2 in monotropein group decreased obviously.The Immunohistochemistry and immunofluorescence stainings showed that monotropein significantly increased the levels of VDR,and arrested tumor growth.ConclusionAs stated previously,Monotropein could prevent inflammation response and tumorigenesis in AOM/DSS-induced colon cancer mice via regulating VDR signals,inhibit the growth of colon cancer cells without obviously time and dose-dependent manner,and prevent tumors growth in nude mice via regulating VDR signals.