Characterisation of microRNA expression in post-natal mouse mammary gland development.

Breast Cancer Functional Genomics Laboratory, Cancer Research UK Cambridge Research Institute and Department of Oncology, University of Cambridge, Li Ka Shing Centre, Cambridge, UK.
BMC Genomics (Impact Factor: 4.04). 01/2009; 10:548. DOI: 10.1186/1471-2164-10-548
Source: PubMed

ABSTRACT The differential expression pattern of microRNAs (miRNAs) during mammary gland development might provide insights into their role in regulating the homeostasis of the mammary epithelium. Our aim was to analyse these regulatory functions by deriving a comprehensive tissue-specific combined miRNA and mRNA expression profile of post-natal mouse mammary gland development.We measured the expression of 318 individual murine miRNAs by bead-based flow-cytometric profiling of whole mouse mammary glands throughout a 16-point developmental time course, including juvenile, puberty, mature virgin, gestation, lactation, and involution stages. In parallel whole-genome mRNA expression data were obtained.
One third (n = 102) of all murine miRNAs analysed were detected during mammary gland development. MicroRNAs were represented in seven temporally co-expressed clusters, which were enriched for both miRNAs belonging to the same family and breast cancer-associated miRNAs. Global miRNA and mRNA expression was significantly reduced during lactation and the early stages of involution after weaning. For most detected miRNA families we did not observe systematic changes in the expression of predicted targets. For miRNA families whose targets did show changes, we observed inverse patterns of miRNA and target expression. The data sets are made publicly available and the combined expression profiles represent an important community resource for mammary gland biology research.
MicroRNAs were expressed in likely co-regulated clusters during mammary gland development. Breast cancer-associated miRNAs were significantly enriched in these clusters. The mechanism and functional consequences of this miRNA co-regulation provide new avenues for research into mammary gland biology and generate candidates for functional validation.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Growing evidence suggests that breast cancer cell plasticity arises due to a partial reactivation of epithelial-mesenchymal transition (EMT) programs in order to give cells pluripotency, leading to a stemness-like phenotype. A complete EMT would be a dead end program that would render cells unable to fully metastasize to distant organs. Evoking the EMT-mesenchymal-to-epithelial transition (MET) cascade promotes successful colonization of distal target tissues. It is unlikely that direct reprogramming or trans-differentiation without passing through a pluripotent stage would be the preferred mechanism during tumor progression. This review focuses on key EMT transcriptional regulators, EMT-transcription factors involved in EMT (TFs) and the miRNA pathway, which are deregulated in breast cancer, and discusses their implications in cancer cell plasticity. Cross-regulation between EMT-TFs and miRNAs, where miRNAs act as co-repressors or co-activators, appears to be a pivotal mechanism for breast cancer cells to acquire a stem cell-like state, which is implicated both in breast metastases and tumor recurrence. As a master regulator of miRNA biogenesis, the ribonuclease type III endonuclease Dicer plays a central role in EMT-TFs/miRNAs regulating networks. All these EMT-MET key regulators represent valuable new prognostic and predictive markers for breast cancer as well as promising new targets for drug-resistant breast cancers.
    World journal of clinical oncology. 08/2014; 5(3):311-22.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Branching epithelial morphogenesis is closely linked to epithelial-to-mesenchymal transition (EMT), a process important in normal development and cancer progression. The miR-200 family regulates epithelial morphogenesis and EMT through a negative feedback loop with the ZEB1 and ZEB2 transcription factors. miR-200 inhibits expression of ZEB1/2 mRNA, which in turn can down-regulate the miR-200 family that further results in down-regulation of E-cadherin and induction of a mesenchymal phenotype. Recent studies show that the expression of miR-200 genes is high during late pregnancy and lactation, thereby indicating that these miRs are important for breast epithelial morphogenesis and differentiation. miR-200 genes have been studied intensively in relation to breast cancer progression and metastasis, where it has been shown that miR-200 members are down-regulated in basal-like breast cancer where the EMT phenotype is prominent. There is growing evidence that the miR-200 family is up-regulated in distal breast metastasis indicating that these miRs are important for colonization of metastatic breast cancer cells through induction of mesenchymal to epithelial transition. The dual role of miR-200 in primary and metastatic breast cancer is of interest for future therapeutic interventions, making it important to understand its role and interacting partners in more detail.
    Genes. 09/2014; 5(3):804-20.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Objective: To investigate the application of bead-based Luminex® xMAP™ technology and to detect the variation of microRNA (miRNA) expression profile in hepatocellular carcinoma (HCC) HepG2 cells compared to normal hepatocytes. Methods: Four hundred and twenty-six miRNAs were labeled and determined using bead-based flow-cytometric microarray platform with total RNA extracted from HepG2 and normal hepatocytes. Fluorescence intensity values were measured with a Luminex 100IS machine. Four miRNAs were selected to be conformed by real-time quantitative RT-PCR (qRT-PCR). Results: Bead-based Luminex® xMAP™ technology succeeded in exploring the miRNA profiles with HepG2 and normal hepatocytes. Twenty-eight miRNAs were detected to be downregulated and 45 upregulated, including a part of miRNAs being reported previously. Detections of 4 miRNAs with real-time qRT-PCR were consistent with bead-based miRNA microarray. Conclusion: Measurement of individual miRNA by the bead-based method is feasible, high speed, sensitive and economic. This technology can be proposed as an alternative method to qRT-PCR for validating miRNA expression data obtained with high-throughput technologies. The variation of the miRNA profiles between HCC and normal hepatic cells indicated that a certain amount of miRNAs may be involved in the hepatocarcinogenesis.

Full-text (2 Sources)

Available from
Jun 5, 2014