Anti-tumor Effects of IL-1β Induced TRAIL-Expressing hUCMSCs on Embelin Treated Breast Cancer Cell Lines

Background: Human umbilical cord mesenchymal stem cells (hUCMSCs) have high therapeutic value in cancer treatment. We have found that pre-activating hUCMSCs with IL-1β promotes tumor necrosis factor-related apoptosis inducing ligand (TRAIL) expression and facilitates anti-tumor effect. Furthermore, embelin has been found to induce apoptosis of different cancer cell lines by upregulating the expression of TRAIL receptor 1 (DR4) and TRAIL receptor 2 (DR5). This study investigated whether IL-1β induced TRAIL-expressing hUCMSCs, in combination with low-dose embelin, could further induce apoptosis in breast cancer cell lines. Materials and Methods: MTT assay was used to examine the cytotoxicity of embelin in MDA-MB-231 and MCF-7. To detect the interested protein expression in cells, Western blot and cell immunofluorescence were used to double-confirm the observed results. Annexin V/PI apoptosis assay was detected by flow cytometry to analyze the apoptosis rate of embelin treated breast cancer cell lines and the effect of co-culturing with breast cancer cells and hUCMSCs. Results: Using Western blot and immunofluorescence, we found that breast cancer cell lines treated with low-dose embelin (2.5-5 μM) increased the expression of apoptosisrelated receptor DR4, DR5 and the cleaved caspase 8, 9 and 3. Moreover, TRAIL expression was enhanced in IL-1β induced hUCMSCs. Combining these observations, we expected that coculturing IL-1β induced hUCMSCs with low dose embelin treated MDA-MB-231 and MCF-7 cells might enhance the apoptosis of breast cancer cells. We confirmed via flow cytometry that coculture of IL-1β induced TRAIL-expressing hUCMSCs and embelin treated MDAMB-231 and MCF-7 cells enhances the apoptosis rate of these breast cancer cells. Conclusion: We found that embelin upregulated the expression of DR4 and DR5 to increase the TRAIL-mediated apoptosis in breast cancer cell lines.