Expression Of ABCG2,HIF-1α In Breast Cancer And The Correlation With Clinical Significance

IntroductionMultidrug resistance(MDR) is one of the main reasons resulting in failure of chemotherapy in patients with breast cancer. The over expression of multidruge resistance associated protein (MRP) play a more important role in MDR, and MRP includes Breast cancer resistant protein (BCRP ABCG2), which discovered lately. Anthracycline is substrates of ABCG2, and properly anthracycline was commonly used in treatment of breast cancer . It is important to investigate the expression of BCRP in breast cancer and the correlation with anthracycline.Hypoxia inducible factor-1(HIF-1) has tightly correlation with MDR, and can up-regulate the expression of P-gp and MRP, which have binding motifs of HIF-1 in promoter field as well as ABCG2. We think that HIF-1 also can up-regulate the expression of ABCG2.In this study, we detected the expression of ABCG2 and HIF-1αusing immunohistochemical SP methods to investigate the relationship between them, as well as the correlate with clinicopathological parameters and Disease Free Survival Time in human breast cancer.Methods1. Patients122 breast cancer patients underwent completely resected which were enrolled from the first affiliated hospital, China Medical University (CMU) . None of them underwent chemotherapy or radiotherapy before operation. But 22 patients (18.0%) received chemotherapy of taxane and 106 patients (86.9%) received chemotherapy of anthtacycline after operation .All the cases were female with median age of 50.2 years,. Among of them there were 32 cases (26.2%) of the tumor size≤2cm, 66 cases (54.1 %) of lymph node metastasis, 88 cases (72.1%) of infitrating ductal carcinoma and 34 (27.9%) advanced cases. 32 patients (26.2%) occurrenced relapse and matastasis .The Diseas Free Survival Time (DFS) ranged from 6 to 59 months. Normal breast tissue of 15 cases was selected as controls.2. MaterialsThe monoclonal antibodies against ABCG2 and SP immunohistochemical kits and DAB substrate solution were purchased from Fujian Maixin Biotechology, Inc; the polyclonal antibodies against HIF-1αwere purchased from Wuhan Boster Biotechnology, Inc.3. MethodsImmunohistochemical staining SP method was performed. All slides were treated with 0.01 mol/L citric acid buffer (PH=6.0) and recovered the antigen activity by autoclave.4. AssessmentOutcome definition of ABCG2 were stained palm yellow particle in cell membrane, positive cells≤10% as negative , >10% as positive , at high magnification(400×). Outcome definition of HIF-1αwere stained palm yellow particle in cytosol or nucelus, positive cells≤10% as negative cells , >10% as positive, at high magnification(400×).5. Statistical analysisStatistical methods x~2 test, Spearman rank correlation test and Kaplan-Meier survival analysis were performed by SPSS software version 13.0. Results1. Expression of ABCG2 and HIF-1αin breast cancer patientsPositive expression of ABCG2,HIF-1αin 122 cases was 40.2%,59.0%,respectively, however, was negative in 15 cases normal breast tissue.2. The relationship between expression of ABCG2 and HIF-1αandclinicopathologic parameters in breast cancer patientsExpression of ABCG2 was positive correlated with tumour size (r=0.21 p=0.02), but not correlated with lymph node metastasis(r=0.04, p>0.05) and clinical stage (r=0.46 P>0.05) . Expression of HIF-1αwas positive correlated with tumour size (r=0.33 p<0.01), lymph node metastasis (r=0.25, p<0.01) and clinical stage (r=0.21, P=0.022) .3.The relationship between expression of ABCG2 and HIF-1αExpression of ABCG2 was positive correlated with HIF-1α(r=0.206, p=0.03).4.The relationship between expression of ABCG2,HIF-1αandDisease Free Survival Time in patients with breast cancerIn 106 patients received chemotherapy of anthtacycline after operation, ABCG2 expression was correlated with DFS by Kaplan-Meier survival analysis (the value of p was 0.033). In 122 patients HIF-1αexpression was correlated with DFS by Kaplan-Meier survival analysis (the value of p was 0.030). The both expression of ABCG2 and HIF-1αwas also correlated with DFS by Kaplan-Meier survival analysis (the value of p was 0.004).Conclusion1 Expression of ABCG2 was bad predictor for patients received chemotherapy of anthtacycline after operation. 2 Expression of ABCG2 was positive correlated with expression of HIF-1α..3 Detection of ABCG2 / HIF-1αin bresat cancer tissues might be significant in prognosis prediction.