A Correlational Study Of The Relationship Between Indoleamine2,3-dioxygenase And Interleukin-6in Breast Cancer

Objective:To study the coexpression of Indoleamine2,3-dioxygenase (IDO) and interleukin-6(IL-6) in breast cancerous tissue, and analyse the relationship between the expression of IDO in situ and serum level of IL-6. To detect the effect of IL-6on IDO secretion of human breast cancer cell line and the possible signal pathway, and to investigate the regulation mechanism of IDO in breast cancer.Methods:1. The paraffin blocks of30cases of breast cancer were collected from Tianjin cancer hospital in January2011. The expression of IDO in breast cancerous tissue was assessed by immunohistochemistry. Serum levels of IL-6were assessed via Enzyme-Linked Immuno-Sorbent Assay (ELISA).To explore relationship between serum level of IL-6and the expression of IDO in situ.2. Immunofluorescence was used to detect the the coexpression of IDO and IL-6in breast cancerous tissue, and analyse the relationship between IL-6and IDO in local tissue.3. culturing MDA-MB-231cells expression of IDO, recombinant human IL-6and IL-6neutralization antibody of different concentration were respectively added. The expression of IDO was detected by Western blotting. We evaluate the influence of IL-6on the expression of IDO in vitro.4. culturing MDA-MB-231cells, IL-6neutralization antibody and JSI-124was respectively added. The expression of IDO and pSTAT3were detected by Western blotting. We evaluate the possible signal pathway of IDO expression effected by IL-6.Results:1. The overexpression ratio of IDO in breast cancer is73.33%(22/30), and expression of IDO was closely associated with tumor size, clinical stage, pathological grade and lymph nodes metastasis(P<0.05).2. The average of serum level of IL-6in breast cancer patients was7.813±4.668pg/ml. The serum level of IL-6was closely associated with tumor size, clinical stage, pathological grade and lymph node metastasis(P<0.05).3. The overexpression of IDO in situ was associated with serum level of IL-6(P=0.023). 4. The Immunofluorescence images were analysed by WCIF Image J analysis software. The expression of IL-6was positively correlated with IDO in tumor tissue(r=0.690, P=0.000).5. In the expression of IDO MDA-MB-231, when the concentration of recombinant human IL-6increased, the expression of IDO increased. The result suggested that recombinant human IL-6can promote the expression of IDO.6. When the concentration of IL-6neutralization antibody increased, the expression of IDO in MDA-MB-231cells decreased. The result suggested that recombinant human IL-6can inhibit the expression of IDO.7. In the culture supernatant, IL-6neutralization antibody and JSI-124was respectively added. Both of the expression of IDO and pSTAT3decreased in consistency. We suggest that IL-6regulates the expression of IDO through the STAT3pathway.Conclusion:1. The expression of IL-6was positively correlated with IDO in tumor tissue.2. In breast cancer, the expression of IDO was positively correlated with IL-6, and serum level of IL-6was associated with the expression of IDO in situ. The results suggest that IL-6effects on the expression of IDO.3. Recombinant human IL-6can promote the expression of IDO and IL-6neutralization antibody can inhibit the expression of IDO in vitro.4. IL-6neutralization antibody and JSI-124was respectively added in MDA-MB-231cells. Both of the expression of IDO and pSTAT3decreased in consistency. The effect of IL-6neutralization antibody is consistent with JSI-124. So we suggest that IL-6regulates the expression of IDO through the downstream STAT3pathway.