Ginsenoside Rg3 decreases breast cancer stem-like phenotypes through impairing MYC mRNA stability.

Breast cancer stem cells (BCSCs) are responsible for breast cancer metastasis, recurrence and treatment resistance, all of which make BCSCs potential drivers of breast cancer aggression. Ginsenoside Rg3, a traditional Chinese herbal medicine, was reported to have multiple antitumor functions. Here, we revealed a novel effect of Rg3 on BCSCs. Rg3 inhibits breast cancer cell viability in a dose- and time-dependent manner. Importantly, Rg3 suppressed mammosphere formation, reduced the expression of stemness-related transcription factors, including c-Myc, Oct4, Sox2 and Lin28, and diminished ALDH(+) populations. Moreover, tumor-bearing mice treated with Rg3 exhibited robust delay of tumor growth and a decrease in tumor-initiating frequency. In addition, we found that Rg3 suppressed breast cancer stem-like properties mainly through inhibiting MYC expression. Mechanistically, Rg3 accelerated the degradation of MYC mRNA by enhancing the expression of the let-7 family, which was demonstrated to bind to the MYC 3' untranslated region (UTR). In conclusion, our findings reveal the remarkable suppressive effect of Rg3 on BCSCs, suggesting that Rg3 is a promising therapeutic treatment for breast cancer.

Analysis of cardiovascular disease-related NF-κB-regulated genes and microRNAs in TNFα-treated primary mouse vascular endothelial cells.

Activated nuclear factor-κB (NF-κB) plays an important role in the development of cardiovascular disease (CVD) through its regulated genes and microRNAs (miRNAs). However, the gene regulation profile remains unclear. In this study, primary mouse vascular endothelial cells (pMVECs) were employed to detect CVD-related NF-κB-regulated genes and miRNAs. Genechip assay identified 77 NF-κB-regulated genes, including 45 upregulated and 32 downregulated genes, in tumor necrosis factor α (TNFα)-treated pMVECs. Ten of these genes were also found to be regulated by NF-κB in TNFα-treated HeLa cells. Quantitative real-time PCR (qRT-PCR) assay confirmed the up-regulation of Egr1, Tnf, and Btg2 by NF-κB in the TNFα-treated pMVECs. The functional annotation revealed that many NF-κB-regulated genes identified in pMVECs were clustered into classical NF-κB-involved biological processes. Genechip assay also identified 26 NF-κB-regulated miRNAs, of which 21 were upregulated and 5 downregulated, in the TNFα-treated pMVECs. Further analysis showed that nine of the identified genes are regulated by seven of these miRNAs. Finally, among the identified NF-κB-regulated genes and miRNAs, 5 genes and 12 miRNAs were associated with CVD by miRWalk and genetic association database analysis. Taken together, these findings show an intricate gene regulation network raised by NF-κB in TNFα-treated pMVECs. The network provides new insights for understanding the molecular mechanism underlying the progression of CVD.

H19/let-7/LIN28 reciprocal negative regulatory circuit promotes breast cancer stem cell maintenance.

Long noncoding RNA-H19 (H19), an imprinted oncofetal gene, has a central role in carcinogenesis. Hitherto, the mechanism by which H19 regulates cancer stem cells, remains elusive. Here we show that breast cancer stem cells (BCSCs) express high levels of H19, and ectopic overexpression of H19 significantly promotes breast cancer cell clonogenicity, migration and mammosphere-forming ability. Conversely, silencing of H19 represses these BCSC properties. In concordance, knockdown of H19 markedly inhibits tumor growth and suppresses tumorigenesis in nude mice. Mechanistically, we found that H19 functions as a competing endogenous RNA to sponge miRNA let-7, leading to an increase in expression of a let-7 target, the core pluripotency factor LIN28, which is enriched in BCSC populations and breast patient samples. Intriguingly, this gain of LIN28 expression can also feedback to reverse the H19 loss-mediated suppression of BCSC properties. Our data also reveal that LIN28 blocks mature let-7 production and, thereby, de-represses H19 expression in breast cancer cells. Appropriately, H19 and LIN28 expression exhibits strong correlations in primary breast carcinomas. Collectively, these findings reveal that lncRNA H19, miRNA let-7 and transcriptional factor LIN28 form a double-negative feedback loop, which has a critical role in the maintenance of BCSCs. Consequently, disrupting this pathway provides a novel therapeutic strategy for breast cancer.