Delphinidin suppresses breast carcinogenesis through the HOTAIR/microRNA-34a axis

Delphinidin, one of the main anthocyanidins, has potent anti-cancer properties. In this study, we investigated the effect of delphinidin on 1-methyl-1-nitrosourea (MNU)-induced breast carcinogenesis on rats and the mechanism of delphinidin via negative regulation of the HOTAIR/microRNA-34a axis. We found administration of delphinidin could effectively suppress MNU-induced mammal breast carcinogenesis. Delphinidin downregulated the level of HOTAIR and upregulated miR-34a in breast carcinogenesis. Western blot analysis confirmed that delphinidin treatment can significantly decrease the expression of beta-catenin, glycogen synthase kinase-3 beta (Gsk3 beta), c-Myc, cyclin-D1, and matrix metalloproteinase-7(MMP-7) expression in breast cancer cells, and inhibition of miR-34a significantly reduced the effect of delphinidin on c-Myc, cyclin-D1, and MMP-7. HOTAIR overexpression also blocked the effect of delphinidin on miR-34a and the Wnt/beta-catenin signaling pathway in MDA-MB-231 cells. RNA immunoprecipitation (RIP) assay and chromatin immunoprecipitation (ChIP) assay results showed that delphinidin upregulated miR-34a by inhibiting HOTAIR, coupled with enhancement of the zeste homolog 2 (EZH2) and histone H3 Lys27 trimethylation (H3K27me3). This study indicated that delphinidin may potentially suppress breast carcinogenesis and exert its anti-cancer effect through the HOTAIR/miR-34a axis. These findings provided new evidence for the use of delphinidin in preventing breast carcinogenesis.