| Background and objective:Colorectal cancer is a common digestive tract malignant tumor.The incidence rate is third of all malignant tumors,and its mortality rate is fifth,which has brought great threat to human health.The etiology of colorectal cancer is not clear,and the pathogenesis of colorectal cancer is very complex.There were no symptoms in the early stage.Operation is the main method to treat colorectal cancer,which has good effect on patients in early stage of colorectal cancer but not in middle and late stage.The patients in middle and late stage of colorectal cancer are easy to metastasize or relapse after operation.For the patients who can not bear operation,the comprehensive treatment mode using chemotherapy can effectively improve the survival of patients.Phenethyl isothiocyanate(PEITC)is a glucosinolate degradation product of Cruciferae Plants,which has been reported to reduce the incidence of tumor,inhibit the proliferation and growth of tumor cells,and have no toxic and side effects on normal tissue cells.At present,it is considered that apoptosis induction was an important mechanism of PEITC to inhibit the proliferation of cancer cells,thus it is essential to understand the apoptosis mechanism induced by PEITC as a clinically useful chemopreventive or therapeutic agent.In our previous studies,we found that PEITC can inhibit the proliferation and induce apoptosis of colon cancer cells,and has no effect on normal intestinal epithelial cells.However,the mechanism was unclear.Therefore,this paper will study the pathway of apoptosis induced by PEITC and its molecular mechanism in vitro,verify the inhibition effect of PEITC on colon cancer tumor,and finally evaluate the safety of PEITC using nude mouse tumor forming model in vivo.This paper will provide a new theoretical basis and a new direction for the clinical treatment of colon cancer.We selected two different colon cancer cell lines(HCT116 and SW620)and normal intestinal epithelial cells(NCM460)treated with different concentrations of PEITC,used MTT method,flow cytometry,clonogenic assay,cell scratch test and transwell test,and found that 20 ?M PEITC can effectively inhibit the proliferation,migration and invasion and induce the apoptosis of colon cancer cells,but has no effect on the proliferation of normal intestinal epithelial cells.Further,we found that PEITC promoted the expression of caspase-9 and Caspase-3 using western blot.The JC-1 and DCFH-DA staining demonstrated PEITC decreased the mitochondrial inner membrane potential and up-regulated the ROS level of colon cancer cells,suggesting a mitochondrial apotosis induced by PEITC.Aafter cytoplasmic components were isolated,we performed western blot experiment to detect the expression of Cyto-c and SMAC,and found that PEITC promoted the expression of SMAC in colon cancer cells.Using flow cytometry,we found that induced apoptosis of colon cancer cells through SMAC.Anti-SMAC Co-immunoprecipitation experiment showed that SMAC interacted with Survivin.PEITC promoted expression of apoptosis related proteins and cell apoptic rate through phosphorylation of ERK and JNK proteins in colon cancer cells.These results indicated that PEITC regulates apoptosis of colorectal cancer cells through ERK and JNK pathway.We next evaluated the antitumor effect and safety of PEITC using the tumor forming model of colon cancer of nude mice,and found that PEITC inhibited the growth of colon cancer,promote the expression of caspase-9,SMAC and inhibit the expression of Survivin in colon cancer,had no effect on blood routine test and liver function in nude mice.Our research demonstrated that PEITC regulates apoptosis of colon cancer cells through SMAC/Survivin signaling pathway.In vivo experiments show that PEITC can inhibit tumor growth,mediate apoptosis of mitochondrial pathway through SMAC/Survivin signal,but don't affect liver function,blood routine test of mice.This paper will provide a new theoretical basis and a new direction for the clinical treatment of colon cancer. |
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