No abstract

Anaplastic thyroid carcinoma (ATC) is the most aggressive malignancy in thyroid cancers. Resistance to current therapies is still a challenge. MicroRNAs are a class of small non-coding RNAs, regulating gene expression. MiR-21 is an oncomiR that is overexpressed in nearly all cancers including ATC. Accumulating evidence suggested that miR-21 has a role in cancer stemness state, apoptosis, cell cycle progression, and differentiation. Therefore, we evaluated the application of Off-miR-21 to sequester the microRNA for therapeutic purposes on ATC cell lines. In this study, C643 and SW1736 were transducted by hsa-miR-21 antagomir (Off-miR-21). PTEN gene expression was performed as a known target of miR-21. Stemness state in cancer stem cells (CSCs) was evaluated by the changes of CSC biomarkers including Oct-4 and ABCG2. Apoptosis was assessed by PDCD4 and Mcl-1 gene expression and flow cytometry. Sodium/iodide symporter (NIS) and thyroglobulin (TG) were measured as ATC differentiation markers. In addition, cell cycle progression was investigated via the alterations of p21 gene expression and flow cytometry. Specific downregulation of miR-21 induced the differentiation and apoptosis in C643 and SW1736. Inversely, the treatment inhibited stemness state and cell cycle progression. Knockdown of miR-21 significantly increased the expression of PDCD4, p21, NIS, and TG while leading to decreased expression of Oct-4, ABCG2, and Mcl-1.Taken together, the results suggest that miR-21, as an oncomiR, has a role not only in stemness state but also in tumor growth, differentiation, and apoptosis. Hence, suppression of miR-21 could pave the way for ATC therapy.

Triple-negative breast cancer (TNBC) is a highly aggressive form of breast cancer. Aberrant expression of genes in mTOR pathway and their targeting miRNAs plays an important role in TNBC. The aim of this study was to determine the expression of mTOR and S6K1 and their targeting miRNAs in breast cancer cell lines and clinical samples. miRNAs targeting 3'-UTR of mTOR and S6K1 mRNAs were predicted using bioinformatic algorithms. MDA-MB-231, MCF-7, and MCF-10A as well as 20 TNBC samples were analyzed for gene and miRNA expression using quantitative real-time PCR (RT-qPCR). A receiver operating characteristic (ROC) curve analysis was performed for evaluation of candidate miRNAs as diagnostic biomarkers. miR-96 and miR-557 targeting mTOR and S6K1 mRNAs, respectively, were selected, and miR-3182 was selected as the miRNA targeting both genes. The miRNAs were down-regulated in cell lines, while their target mRNAs were up-regulated. Similar findings were observed in clinical samples. The ROC curve analysis revealed decline in expression of these miRNAs. We suggest that miR-96, miR-557, and miR-3182 can be used as inhibitory agents for mTOR and S6K1 in TNBC-targeted therapy.

Background New insights on cellular and molecular aspects of both oligodendrocyte (OL) differentiation and myelin synthesis pathways are potential avenues for developing a cell-based therapy for demyelinating disorders comprising multiple sclerosis. MicroRNAs (miRNA) have broad implications in all aspects of cell biology including OL differentiation. MiR-184 has been identified as one of the most highly enriched miRNAs in oligodendrocyte progenitor cells (OPCs). However, the exact molecular mechanism of miR-184 in OL differentiation is yet to be elucidated. Methods and results Based on immunochemistry assays, qRT-PCR, and western blotting findings, we hypothesized that overexpression of miR-184 in either neural progenitor cells (NPCs) or embryonic mouse cortex stimulated the differentiation of OL lineage efficiently through regulating crucial developmental genes. Luciferase assays demonstrated that miR-184 directly represses positive regulators of neural and astrocyte differentiation, i.e., SOX1 and BCL2L1, respectively, including the negative regulator of myelination, LINGO1. Moreover, blocking the function of miR-184 reduced the number of committed cells to an OL lineage. Conclusions Our data highlighted that miR-184 could promote OL differentiation even in the absence of exogenous growth factors and propose a novel strategy to improve the efficacy of OL differentiation, with potential applications in cell therapy for neurodegenerative diseases. Electronic supplementary material The online version of this article (10.1186/s13287-019-1208-y) contains supplementary material, which is available to authorized users.

Breast cancer is a heterogeneous disease, and among all types, triple-negative breast cancer (TNBC) is characterised by high risk of recurrence. The discovery of microRNAs (miRNA) has opened the door for targeted therapy of TNBC. miR-340 down-regulation and sub-G1-accumulated cells in flowcytometry were observed in metastatic TNBC cells (data in publication), leading us to investigate the potential tumour suppressive role of this miRNA on cell-cycle-related genes. A lentiviral vector containing miR-340 was applied to over-express miR-340 in TNBC cell line, MDA-MB-231. Then, the expression of some cell-cycle-regulating genes including cyclin A2 (cyclin A2), Cyclin-dependent kinases 2 (CDK2), cyclin-dependent kinase inhibitors (P16, P18 and P27), Retinoblastoma (RB) and transcription factors (SMAD 4, SOX2 and SOX17) was investigated using quantitative RT-PCR. The results showed a decline in the expression of SOX2, P16 and P27 after miR-340 over-expression, whereas we observed an increase in the expression of cyclin A2, CDK2, SOX17, P18, SMAD 4 and RB. The over-expression of tumour suppressor genes such as RB and SOX17 and down-regulation of an oncogene such as SOX2 were in accordance to the inhibitory role of miR-340 that causes blockage of breast cancer metastasis which should be further investigated.