The Research On Indoleamine 2,3-dioxygenase And Chemotherapy Efficacy In Breast Cancer

Objectives:The aim of this study was to investigate the expression of indoleamine2,3-dioxygenase(IDO)in local tumor tissues and its activity in peripheral blood of breast cancer patients before neoadjuvant chemotherapy,and to explore the correlation between them.At the same time,based on the analysis of clinical and pathological data of patients,it was purposed to elaborate whether IDO expression in tumor tissue and its activity in peripheral blood before chemotherapy associated with neoadjuvant chemotherapy efficacy,in order to provide promising information for clinical prediction of chemotherapy sensitivity.Furthermore,through establishing the paclitaxel(PTX)-resistant cell lines of human breast cancer MCF-7,MDA-MB-231 and SKBR-3,we try to detect IDO protein expression,IDO activity and IDO mRNA expression in primary and resisent cell line.So that to explore the change of IDO protein and mRNA expression after PTX resistance of breast cancer cells may provide a new target for the treatment of malignant tumor after chemotherapy resistance.Methods: 1.Collecting tumor tissue specimens and peripheral blood specimens of 53 breast cancer patients undergoing neoadjuvant chemotherapy in Tianjin Medical University Cancer Institute and Hospital from September 2015 to December 2016.Immunohistochemistry(IHC)and high-performance liquid chromatography(HPLC)were used to measure IDO protein expression in tumor tissue,kynurenine(Kyn),tryptophan(Trp)and IDO activity(Kyn/Trp)in peripheral blood.The correlation between expression and activity of IDO and chemotherapy efficacy were analyzed.2.With paclitaxel as the inducer drug,MCF-7/PTX,MDA-MB-231/PTX and SKBR-3/PTX resistant cell lines were established by intermittent inducement.Cell Counting Kit-8(CCK-8)assays were performed on original and paclitaxel-resistant breast cancer cells,and the half-inhibitory concentration(IC50)of each cell line was calculated.3.Western blots(WB),HPLC and Real-time PCR(RT-PCR)analyzed IDO protein expression,enzyme activity and mRNA expression in original breast cancer cells(MCF-7,MDA-MB-231 and SKBR-3)and paclitaxel-resistant cells(MCF-7/PTX,MDA-MB-231/PTX and SKBR-3/PTX).Result: 1.The 28 cases(52.83%)had high IDO expression in the tumor tissues of 53 breast cancer patients before neoadjuvant chemotherapy.The expression of IDO in tumor tissue before neoadjuvant chemotherapy increased with advanced clinical tumor stages(P=0.006),node stages(P=0.020)and clinical stages(P=0.045),while high IDO expression was more frequently in estrogen receptor(ER)positive patients(P = 0.014).2.The mean activity of IDO in peripheral blood before neoadjuvant chemotherapy was 0.044±0.015 in 53 patients with breast cancer.Prior to neoadjuvant chemotherapy,IDO activity in peripheral blood increased with advanced clinical tumor stages(P=0.019)and node stages(P=0.047).3.Patients who had higher IDO expression in breast tumor tissues before neoadjuvant chemotherapy,their IDO activity was elevated in peripheral blood(P=0.004).In addition,IDO expression in tumor tissue and IDO activity in peripheral blood before neoadjuvant chemotherapy were related to the clinical efficacy and pathologic complete response(pCR)of neoadjuvant chemotherapy(P<0.05).Multivariate analysis showed that IDO activity in peripheral blood before neoadjuvant chemotherapy was the only independent factor that affected pCR(P=0.032).4.In paclitaxel-resistant breast cancer cell lines,the final paclitaxel resistant concentration of MCF-7/PTX,MDA-MB-231/PTX and SKBR-3/PTX were 500 nM,200nM and 200 nM respectively.CCK-8 assays showed significant differences in IC50 between original and paclitaxel-resistant cells in MCF-7,MDA-MB-231 and SKBR-3 cell lines(P<0.05).5.Western blots showed that compared with original breast cancer cells,the expression of IDO was enhanced in paclitaxel-resistant cell lines MCF-7/PTX,MDA-MB-231/PTX and SKBR-3/PTX.6.HPLC analysis showed the IDO enzyme activity was significantly increased in paclitaxel-resistant cells MCF-7/PTX,MDA-MB-231/PTX,and SKBR-3/PTX compared with original breast cancer cells,and the difference was statistically significant(P<0.05).7.RT-PCR showed that the expression level of IDO mRNA was significantly higher in paclitaxel-resistant cells MCF-7/PTX,MDA-MB-231/PTX,and SKBR-3/PTX compared with original breast cancer cells,and the difference was statistically significant(P<0.05).Conclusions:1.In patients with breast cancer,high IDO activity before neoadjuvant chemotherapy in peripheral blood was associated with high IDO expression in tumor tissue,and IDO activity in peripheral blood can indicate the IDO expression level in tumors.Meanwhile IDO expression in tumor tissues and its activity in peripheral blood prior to neoadjuvant chemotherapy were closely related to tumor size and lymph node metastasis.2.IDO expression of tumor tissue and IDO activity of peripheral blood before chemotherapy were both associated with chemotherapy efficacy,and chemotherapy-insensitive patients had high expression of IDO and increased IDO activity,which could provide promising information for clinical prediction of chemotherapy sensitivity.3.The protein expression,activity and mRNA expression level of IDO were all significantly increased in paclitaxel-resistant breast cancer cell lines,which suggested the IDO expression in breast cancer drug-resistant cells may provide a new target for the treatment of malignant tumor after chemotherapy resistance.