Effect of Enterolactone on the Regulation of Indoleamine 2,3-Dioxygenase in MCF-7 Cancer Cells

Background and Objective: Indoleamine 2,3-dioxygenase 1 (IDO1) plays a key role in immune escape and tumor survival in various cancers. Numerous studies have shown that several antioxidants inhibit the expression of IDO1 in cancer cells. The purpose of this work was to examine how enterolactone (ENL), a bioactive metabolite from dietary lignans effects the IDO1 enzyme in breast cancer (MCF-7). Materials and Methods: The Er"-positive human breast cancer cell line, Michigan Cancer Foundation-7 (MCF-7) was utilized and induced to produce IDO1 by stimulating the cells with IFN-gamma. Subsequently, the cells were cultured in the presence of enterolactone and their response was evaluated by measuring IDO enzymatic activity using the Enzyme-Linked Immunosorbent Assay (ELISA). Furthermore, the impact of ENL on the cytotoxicity and apoptosis of cancer cells was assessed. Results: The cell viability assay show that ENL had no impact on the viability of MCF-7 cells. The MCF-7 cancer cell line expresses IDO1, as detected by ELISA and its expression is further increased in response to IFN-. treatment. The IDO1 activity increased with the different concentrations used of ENL and is significantly increased with 100 mu M ENL. Apoptosis assay revealed no significant difference between the control and treated cells. Conclusion: This work provides the first proof of the impact of ENL on the immunosuppressive enzyme IDO1 in MCF7 cells activated by IFN-(. Interestingly, it was discovered that high ENL concentrations increased IDO1 activity. Because ENL has IDO1-induced activity, more research on them is necessary.