IDO Inhibitors Combined Transport Stat3-siRNA Attenuated Salmonella Against Breast Cancer In Mice

BackgroundBreast cancer occur in mammary gland epithelial malignant tumor.Because of the diversity of causes,the single treatment has limited effect,we expect to find an effective combination treatment scheme.Studies found that IDO was one kind of the immune inhibitory of tryptophan metabolism in the speed limit of enzymes.Inhibition of the expression of IDO can effectively improve the body’s anti-tumor immune responses.STAT3is a member of the STAT protein family,and it has been shown to be highly expressed in a variety of tumors,promote the progress of tumor,inhibit the body anti-tumor immune response,improve the expression of IDO at the same time.RNAi technology can through the length of the 21-25 nt small double-stranded RNA interference,specific target RNA degradation,blocking the synthesis of the corresponding protein.Therefore,we hypothesized that using RNAi technology to inhibit Stat3,combined with IDO inhibitors,to study its therapeutic effect on breast cancer of mouse.ObjectiveTo explore whether the IDO inhibitor combined with stat3-siRNA attenuated salmonella can enhance the anti-tumor immunological effect of breast cancer tumor-bearing mice.MethodsEMT-6 cells were inoculated subcutaneously into Balb/c mice,and the tumor-bearing mice were randomly divided into five groups:the model group(PBS),D-MT group(D-MT),transport Scramble-siRNA attenuated salmonella group(Scramble-siRNA),transport Stat3-siRNA attenuated salmonella group(Stat3-siRNA),D-MT+transport Stat3-siRNA attenuated salmonella group(D-MT+Stat3-siRNA).IDO inhibitor dosage in abdominal cavity,1 day 1 time and last for 1 week,carrier interference fragment of attenuated salmonella group within the tumor injection,1 week to 1,treatment 2weeks.After the treatment,the tumor was weighed,and the tumor size of each group was compared;Western blot:detect a tumor-burdened mice tumor immune related protein expression of CD8~+T lymphocytes;The expression of CD8~+T lymphocytes in tumor tissues was deteced by IHC;Haematoxylin-eosin staining measure the model groups and different treatment groups of the breast cancer tumor-bearing mice’tumor tissue,compared the change of the adipocytes;Flow cytometry:Extraction of spleen tissue the model groups and different treatment groups of the breast cancer tumor-bearing mice,CD3,CD4,CD8,NK and other immunological indicators were detected.Results1.Comparing the model group with the tumor size of breast cancer in different treatment groups,Tumor contrast found at the end of the treatment,combined group significantly inhibited tumor growth;2.Comparing with the model groups and different treatment groups of the breast cancer tumor-bearing mice,HE staining results showed that the treatment group especially combination therapy appear a large number of apoptosis cells in a tumor tissue;3.According to the results of that model groups in mice tumor tissue compared with treatment groups,Western blot showed that combination therapy raised CD8 expression in mice,reducing MMP2 expression;4.Comparing indexes of CD3,CD4,CD8,NK1.1 with the model groups and different treatment groups of the breast cancer tumor-bearing mice’spleen tissues,Flow cytometry showed that the NK1.1 content was the highest in the combined group,and CD4,CD8expression is the highest after CD3 was labeled.ConclusionIDO inhibitor combined Stat3-siRNA treatment can significantly inhibit the growth of breast cancer tumor-bearing mice’tumor,its mechanism may be by increasing the number of immune cells.