IntroductionThe miR-183/-96/-182 cluster is a conserved polycistronic microRNA (miRNA) cluster which is highly expressed in most breast cancers. Although there are some sporadic reports which demonstrate the importance of each miRNA in this cluster in breast cancer, the biological roles of this cluster as a whole and its regulation mechanisms in breast cancer are still unclear. We compared the expression of this cluster in different cancer types, analyzed the regulation mechanism of this cluster, identified new target genes, and examined the impact of this cluster on breast cancer cells.MethodsThe miRNA level was detected by LNA-based northern blot and Real-time PCR, and was also analyzed from TCGA dataset. Bioinformatics research and luciferase assay were applied to find the promoter regions and transcription factors. To investigate the biological effects of the miR-183/-96 /-182 cluster in breast cancer, we generated miR-96, miR-182 and miR-183 overexpression stable cell lines to check the overdose effects; we also used miR-Down™ antagomir for each miRNA as well as miR-183/-96 /-182 cluster sponge lentivirus to check the knockdown effects. Growth, migration, cell cycle profile and survival of these cells was then monitored by colony formation assay, MTT assay, cell wound healing assay, flow cytometry and microscopy. The target gene was validated by Real-time PCR, luciferase assay, Western blot and Phalloidin/DAPI counterstaining.ResultsThe miR-183/-96/-182 cluster was highly expressed in most breast cancers, and its transcription is disordered in breast cancer. The miR-183/-96/-182 cluster was transcribed in the same pri-miRNA and its transcription was regulated by ZEB1 and HSF2. It increased breast cell growth by promoting more rapid completion of mitosis, promoted cell migration and was essential for cell survival. MiR-183 targeted the RAB21 mRNA directly in breast cancer.ConclusionThe miR-183/-96/-182 cluster is up-regulated in most breast cancer. It functions as an oncogene in breast cancer as it increases cell proliferation and migration.Electronic supplementary materialThe online version of this article (doi:10.1186/s13058-014-0473-z) contains supplementary material, which is available to authorized users.

Nucleostemin (NS) encodes a nucleolar GTP-binding protein highly enriched in the stem cells and cancer cells. To determine its biological activity in vivo, we generated NS loss-and gain-of-function mouse models. The embryogenesis of homozygous NS-null (NS؊/؊ ) mice was aborted before the blastula stage. Although the growth and fertility of heterozygous NS-null (NS ؉/؊ ) mice appeared normal, NS ؉/؊ mouse embryonic fibroblasts (MEFs) had fewer NS proteins, a lower population growth rate, and higher percentages of senescent cells from passage 5 (P5) to P7 than their wild-type littermates. Conversely, transgenic overexpression of NS could rescue the NS ؊/؊ embryo in a dose-dependent manner, increase the population growth rate, and reduce the senescent percentage of MEFs. Cell cycle analyses revealed increased pre-G 1 percentages in the late-passage NS ؉/؊ MEF cultures compared to the wild-type cultures. We demonstrated that NS could interact with telomeric repeat-binding factor 1 (TRF1) and enhance the degradation but not the ubiquitination of the TRF1 protein, which negatively regulates telomere length and is essential for early embryogenesis. This work demonstrates the roles of NS in establishing early embryogenesis and delaying cellular senescence of MEFs and reveals a mechanism of a NS-regulated degradation of TRF1.Stem cells are defined by their abilities to self-renew and to generate multiple cell types in the tissues where they reside. Expression profile studies indicate that the molecular characteristics of embryonic and somatic stem cells are likely to be governed by a combination of stem cell-enriched factors rather than by a single master program (4, 9). One of the stem cellenriched genes is nucleostemin (NS), which encodes a novel nucleolar GTP-binding protein found at high levels in the neural stem cells, embryonic stem (ES) cells, c-kit ϩ bone marrow cells, adult testes, and tumor cell lines (24) as well as in the mesenchymal and stromal stem cells (1, 10) and several types of human cancers (16).Perturbation of NS expression in vitro shows that it is required for maintaining the proliferation of neural stem cells and some human cancer cell lines by a mechanism not completely understood (16,22,24). The expression of NS does not correlate completely with cell division (24) or with the sites of nascent rRNAs and 28S RNA-containing ribosomes (20), suggesting that it is not simply a cell cycle or rRNA-processing protein. An indication of the NS activity is revealed by its ability to bind p53, a key factor involved in cell cycle progression and cellular senescence (24). The interaction between NS in the nucleolus and p53 in the nucleoplasm is made possible in the living cells by a GTP-regulated shuttling of NS between the nucleolar and nucleoplasmic compartments (23). While NS is essential for maintaining the proliferation of stem cells and cancer cells in vitro, its function in the developing embryos has not yet been examined. To determine the physiological roles of NS, we generated heterozygous NS-null (N...

MicroRNA-183 (miR-183), miR-96, and miR-182 comprising the miR-183/96/182 cluster are highly expressed in photoreceptor cells. Although in vitro data have indicated an important role for this cluster in the retina, details of its in vivo biological activity are still unknown. To observe the impact of the miR-183/96/ 182 cluster on retinal maintenance and light adaptation, we generated a sponge transgenic mouse model that disrupted the activities of the three-component microRNAs simultaneously and selectively in the retina. Although our morphological and functional studies showed no differences between transgenic and wild type mice under normal laboratory lighting conditions, sponge transgenic mice displayed severe retinal degeneration after 30 min of exposure to 10,000 lux light. Histological studies showed that the outer nuclear layer thickness was dramatically reduced in the superior retina of transgenic mice. Real time PCR experiments in both the sponge transgenic mouse model and different microRNA stable cell lines identified Arrdc3, Neurod4, and caspase-2 (Casp2) as probable downstream targets of this cluster, a result also supported by luciferase assay and immunoblotting analyses. Further studies indicated that expression of both the cluster and Casp2 increased in response to light exposure. Importantly, Casp2 expression was enhanced in transgenic mice, and inhibition of Casp2 partially rescued their light-induced retinal degeneration. By connecting the microRNA and apoptotic pathways, these findings imply an important role for the miR-183/96/182 cluster in acute light-induced retinal degeneration of mice. This study demonstrates a clear involvement of miRs in the physiology of postmitotic cells in vivo. MicroRNAs (miRs)2 are endogenous and short (about 22 nucleotides) noncoding RNA molecules that bind to complementary sequences in the 3Ј-UTR of multiple target mRNAs, usually inhibiting their translation or causing their destabilization (1, 2). miRs are well conserved in eukaryotic organisms and widely expressed in different tissues and cell types (3). To date, 885 and 689 miRs have been identified in human and mouse genomes, respectively (miRBASE Release 13.0, March, 2009). Each miR regulates about 200 -800 target genes, and 60% of protein-encoding genes in humans are predicted to be regulated by miRs (4). Several miRs are tissue-specific, suggesting specialized roles in tissue differentiation and maintenance (5, 6). Progress toward identifying the in vivo functions of miRs has been limited, not only by the complex biology of these molecules but also by the experimental accessibility of the biological systems that they affect.The retina is a layered tissue in the back of the eye that contains specialized photoreceptor cells called rods and cones as well as other cell types, including ganglion, bipolar, horizontal, and amacrine cells (7). Its development, maintenance, and light-sensitive visual functions are highly regulated. At least 78 miRs are preferentially expressed in vertebrate retina (6,8,9), indic...

Biodegradable microspheres have been widely used in the field of medicine due to their ability to deliver drug molecules of various properties through multiple pathways and their advantages of low dose and low side effects. Poly (lactic-co-glycolic acid) copolymer (PLGA) is one of the most widely used biodegradable material currently and has good biocompatibility. In application, PLGA with a specific monomer ratio (lactic acid and glycolic acid) can be selected according to the properties of drug molecules and the requirements of the drug release rate. PLGA-based biodegradable microspheres have been studied in the field of drug delivery, including the delivery of various anticancer drugs, protein or peptide drugs, bacterial or viral DNA, etc. This review describes the basic knowledge and current situation of PLGA biodegradable microspheres and discusses the selection of PLGA polymer materials. Then, the preparation methods of PLGA microspheres are introduced, including emulsification, microfluidic technology, electrospray, and spray drying. Finally, this review summarizes the application of PLGA microspheres in drug delivery and the treatment of pulmonary and ocularrelated diseases.

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