Effects Of Alkaloids From Coptis Root On The Colon Cancer And It's Molecular Mechanism

Objective:To investigate the anti-colon cancer effects of alkaloids from Coptis root and possible molecular mechaism.Methods:1. Wistar rat colon cancer model was induced by 1-2 dimethylhydrazine (DMH)(40 mg/kg sc) + 1% dextran sodium sulfate solution (DSS)(freely drinking). All rats were randomly divided into 6 groups:(1)control group:DMH + DSS; (2)meloxicam low dose group: DMH +DSS + Mel 0.45 mg/kg;(3)meloxicam high dose group: DMH + DSS+ Mel 1.35 mg/kg;(4)Tal low dose group: DMH + DSS + Tal 120 mg/kg; (5)Tal high dose group: DMH + DSS + Tal 360 mg/kg;(6)berberine group: DMH + DSS + Ber 100 mg/kg. The number of rat colon ACFs was observed by methylene blue staining. The body weight,incidence,and number of colon cancer were counted. The changes of rat colon tissues in morphology were observed through hematoxylin-eosin (HE) stainning.2. Human colon cancer lovo cell line was treated by Tal,Ber,mel,and ros in various concentrations (10-6 mol/l,10-5 mol/l,10-4 mol/l,10-3mol/l) for 6 h,12 h,and 24 h,respectively, and the cell growth was assayed by MTT method. 3.Lovo cell was treated by Ber(10-5 mol/l)with or without GW9662(10-7 mol/l),and ros(10-5 mol/l)with or without GW9662(10-7 mol/l)for 24 h. The cell growth was assayed by MTT method.4.RT-PCR and western-blot were used to evaluate the mRNA and protein expressions of COX-2,PPARγin lovo cell treated with Ber and ros alone or combination with GW9662 for 24 h.Results:1. The effect of Tal/Ber on the growth and development in rat administrated with DMH+DSS Tal, Ber could significantly improve the dyscrasia induced by DMH+DSS, the body weight and general condition were both better than control group.2.The effect of Tal/Ber on the number of ACF At 10 week after adminstration of DMH+DSS the number of ACF of DMH+DSS group was 19.2±3.5/rat. Tal significantly inhibited ACF incidence in dose-dependent manner(P<0.05),compared with control (P<0.01); Similar results were observed in the Mel high and low dose group. Ber group also significantly inhibited the formation of ACF, compared with control(P<0.01). The significant difference on the number of ACF failed to be found among Tal high dose,Mel high dose,and Ber groups.3.The effect of Tal/Ber on colon cancer At 20 week after the treatment with DMH+DSS, the incidence of the colon cancer was 80% in control,which much higher than that of intervention groups(P<0.01). The incidences of the colon cancer were 40%, 26.7%, 33.3%, 25% and 33.3%, respectively in Tal low and high dose , Mel low and Mel high dose,and Ber groups. And all intervention drugs had no effects on the differentiation of cancer.4.The effect of inbibition in lovo cell treated with Tal/Ber and the possible relationship with PPARγand COX-2 Tal,Ber,positive control Ros,and Mel could inhibit the growth and proliferation of lovo cell in concentration- and time-dependent manners (P<0.05 or P<0.01). Apoptosis of lovo cell was more conspicuous,which induced by Tal than that by other drugs with same concentrations. The IC50 values for 24 h contact of drugs were 2.83±0.23μmol/l,3.22±0.1μmol/l,4.99±0.17μmol/l and 3.14±0.135μmol/l, respectively in Tal, Ber, Mel and Ros respectively.The apoptosis caused by Ros but not Ber was reversed by pretreatment with the specific PPARγantagonist GW9662. The expression levels of COX-2 mRNA,COX-2 protein,and PPARγmRNA were decreased after adminstration of Ber or Ros,but only later`s effect was blocked by pretreatment with GW9662.Conclusion:1.Tal, Ber can inhibit ACF and tumor formation induced by DMH + DSS. This results suggested that Tal,Ber are useful for colon cancer chemoprevention.2.Tal,Ber can decrease the lovo cell proliferation index and apoptosis index. The effects of coptis alkaloids were significantly higher than that of other drugs. This means that other aikaloids from the coptis may have a certain anti-tumor effects except Ber.3.The anti-tumor effects of Ber may not be related with PPARγ.4.The anti-tumor effects of Ber may involve in unknown pathway through which the expressions of COX-2 mRNA and protein were inhibited.