Down-regulation Of Notch1Expression By Xanthohumol Inhibits Breast Cancer Cells Growth

The Notch signaling pathway is a highly conserved signaling pathway. It is involved in the regulation of many important biological events, including the cell proliferation, differentiation, apoptosis, adhesion, epithelial-mesenchymal transition process. The disorder of Notch signal may lead to tumorigenesis. Notchl is an integral member of the Notch receptor family. In many cancers, the Notchl keeps abnormal high expression, In this case, down-regulating the expression of Notchl can efficiently control the Notch signaling pathway. Hesl is the most typical downstream target gene, which plays an important role in the Notchl signaling pathway. Because of the important role of the Notch signaling pathway in breast cancer development process, the study of the Notch signaling pathway inhibitors has been one of the hotspots of the breast cancer research.Xanthohumol (Xanthohumol, XN) is one of the primary isopentenyl flavonoids found in hops resin. It has a variety of biological activity. Previous studies have reported that Xanthohumol can effectively inhibit breast cancer cell proliferation. However, the mechanisms of Xanthohumol inhibition in breast cancer cell growth remains unclear.In this thesis, we hypothesized that the Notch signaling pathway is a targeted by Xanthohumol leading to inhibit the breast cancer cell growth. In this study, expressions of Notchl and Hesl in MCF-7, MDA-MB-231, L02and293T cells were detected by RT-PCR and Western blot. The results showed that Notch1and Hes1expression were significantly up-regulated in MCF-7and MDA-MB-231cells. Luciferase reporter assays were performed to preliminary assess the function of Xanthohumol inhibition of Notchl activity. The further investigation of Xanthohumol inhibiting Notchl and Hesl expression were performed by Western blot and RT-PCR. The experiment results show that Notchl and Hesl were dose down-regulated by different concentration Xanthohumol treatment (5,10and20μM). Cell wounding heal and Western blot analysis showed that down-regulation of Notchl expression by Xanthohumol treatment inhibited breast cancer cell migration. The flow cytometry cycle analysis and Western blot analysis found that down-regulating expression of Notchl by Xanthohumol treatment induced cell cycle arresting in G0/G1phase. The inhibition of breast cancer cells proliferation by Xanthohumol treatment were measured by MTT assay and Western blot. The results show that Xanthohumol can significantly down-regulate the expression of two proliferation-promoting genes, Survivin and c-myc, which are regulated by Notchl. Western blot analysis showed that Xanthohumol significantly down-regulated the expression of two anti-apoptotic genes, Bcl-xL and Bcl-2, which are also regulated by Notchl. At the same time, Xanthohumol can promote the degradation of PARP, which promotes cell apoptosis. In summary, Xanthohumol can inhibit the Notch1expression of Notch signaling pathway in MCF-7and MDA-MB-231cells, which leads to the inhibition of the breast cancer cell growth. This study provides theory evidence that Xanthohumol can be a potential inhibitor of Notch sinaling pathway. Thus, Xanthohumol has good application prospects.In summary, Xanthohumol is inhibiting the growth of MCF-7and MDA-MB-231cells by inhibiting the the expression of Notchl. The results of these studies provide the theoretical basis of Xanthohumoi may be potential inhibitors of Notch signaling pathway, which may be have a good application prospects.