miR-145 transgenic mice develop cardiopulmonary complications leading to postnatal death.

BACKGROUND: Both downregulation and elevation of microRNA miR-145 has been linked to an array of cardiopulmonary phenotypes, and a host of studies suggest that it is an important contributor in governing the differentiation of cardiac and vascular smooth muscle cell types. METHODS AND RESULTS: To better understand the role of elevated miR-145 in utero within the cardiopulmonary system, we utilized a transgene to overexpress miR-145 embryonically in mice and examined the consequences of this lineage-restricted enhanced expression. Overexpression of miR-145 has detrimental effects that manifest after birth as overexpressor mice are unable to survive beyond postnatal day 18. The miR-145 expressing mice exhibit respiratory distress and fail to thrive. Gross analysis revealed an enlarged right ventricle, and pulmonary dysplasia with vascular hypertrophy. Single cell sequencing of RNA derived from lungs of control and miR-145 transgenic mice demonstrated that miR-145 overexpression had global effects on the lung with an increase in immune cells and evidence of leukocyte extravasation associated with vascular inflammation. CONCLUSIONS: These data provide novel findings that demonstrate a pathological role for miR-145 in the cardiopulmonary system that extends beyond its normal function in governing smooth muscle differentiation.

MicroRNA-145 targets in cancer and the cardiovascular system: evidence for common signaling pathways.

miRNAs are small regulatory RNAs which govern gene expression post-transcriptionally by primarily binding to the 3'-UTR of mRNA target genes. miR-145 is a well-studied miRNA that has been implicated in controlling a range of biological processes. miR-145 is expressed in a variety of tissues and cell types and acts as a tumor-suppressor by regulating target gene signaling pathways involved in different aspects of tumor growth and progression. There is also strong evidence that highlights the important functions of miR-145 in the cardiovascular system. Here, we review the mechanisms of miR-145 in tumorigenesis and cancer progression and compare and contrast with the roles of miR-145 in cardiovascular development and disease. We discuss the important targets of miR-145 in cancer and their possible link to the cardiovascular system.

Generation of transgenic mice that conditionally express microRNA miR-145.

MicroRNAs are modulators of cellular phenotypes and their functions contribute to development, homeostasis, and disease. miR-145 is a conserved microRNA that has been implicated in regulating an array of phenotypes. These include supporting smooth muscle differentiation, repression of stem cell pluripotency, and inhibition of tumor growth and metastasis. Previously, our lab demonstrated that miR-145 acts to suppress cardiac fibrosis through inhibition of the TGF-ß signaling pathway. The range of effects that miR-145 has on different cell types makes it an attractive microRNA for further study. Here we describe the generation of transgenic mice that conditionally express miR-145 through Cre recombinase-mediated activation. Characterization of individual founder lines indicates that overexpression of miR-145 in the developing cardiovascular system has detrimental effects, with three independent miR-145 transgenic lines exhibiting Cre-dependent lethality. Expression analysis demonstrates that the transgene is robustly expressed and our analysis reveals a novel downstream target of miR-145, Tnnt2. The miR-145 transgenic mice represent a valuable tool to understand the role of miR-145 in diverse cell types and to address its potential as a therapeutic mediator for the treatment of disease.

Biological Evaluation of a Fluorescent-Imaging Agent for Medullary Thyroid Cancer in an Orthotopic Model.

Context: The primary and definitive treatment of medullary thyroid cancer (MTC) is surgical resection. Recurrent or residual disease is typically a result of incomplete surgical removal. Objective: Our objective is to develop a compound that assists in intraoperative visualization of cancer, which would have the potential to improve surgical cure rates and outcomes. Results: We report the biological characterization of Compound-17, which is labeled with IRdye800, allowing fluorescent visualization of MTC mouse models. We found that the agent has high affinity for two human MTC cell lines (TT and MZ-CRC1) in vitro and in vivo. We further tested the affinity of the compound in a newly developed MTC orthotopic xenograft model and found that Compound-17 produces fluorescent signals within MTC-derived orthotopic xenografts in comparison with a sequence-jumbled control compound and surrounding normal tissues. Conclusions: Compound-17 is a unique and effective molecule for MTC identification that may have therapeutic potential.

Novel pyrrolopyrimidines as Mps1/TTK kinase inhibitors for breast cancer.

New targeted therapy approaches for certain subtypes of breast cancer, such as triple-negative breast cancers and other aggressive phenotypes, are desired. High levels of the mitotic checkpoint kinase Mps1/TTK have correlated with high histologic grade in breast cancer, suggesting a potential new therapeutic target for aggressive breast cancers (BC). Novel small molecules targeting Mps1 were designed by computer assisted docking analyses, and several candidate compounds were synthesized. These compounds were evaluated in anti-proliferative assays of a panel of 15 breast cancer cell lines and further examined for their ability to inhibit a variety of Mps1-dependent biological functions. The results indicate that the lead compounds have strong anti-proliferative potential through Mps1/TTK inhibition in both basal and luminal BC cell lines, exhibiting IC50 values ranging from 0.05 to 1.0µM. In addition, the lead compounds 1 and 13 inhibit Mps1 kinase enzymatic activity with IC50 values from 0.356µM to 0.809µM, and inhibited Mps1-associated cellular functions such as centrosome duplication and the spindle checkpoint in triple negative breast cancer cells. The most promising analog, compound 13, significantly decreased tumor growth in nude mice containing Cal-51 triple negative breast cancer cell xenografts. Using drug discovery technologies, computational modeling, medicinal chemistry, cell culture and in vivo assays, novel small molecule Mps1/TTK inhibitors have been identified as potential targeted therapies for breast cancers.