Advances, nuances, and potential pitfalls when exploiting the therapeutic potential of RNA interference

Inhibition of galectins in cancer: Biological challenges for their clinical application

Galectins play relevant roles in tumor development, progression and metastasis. Accordingly, galectins are certainly enticing targets for medical intervention in cancer. To date, however, clinical trials based on galectin inhibitors reported inconclusive results. This review summarizes the galectin inhibitors currently being evaluated and discusses some of the biological challenges that need to be addressed to improve these strategies for the benefit of cancer patients.

Putting the "mi" in omics: discovering miRNA biomarkers for pediatric precision care

In the past decade, growing interest in micro-ribonucleic acids (miRNAs) has catapulted these small, non-coding nucleic acids to the forefront of biomarker research. Advances in scientific knowledge have made it clear that miRNAs play a vital role in regulating cellular physiology throughout the human body. Perturbations in miRNA signaling have also been described in a variety of pediatric conditions-from cancer, to renal failure, to traumatic brain injury. Likewise, the number of studies across pediatric disciplines that pair patient miRNA-omics with longitudinal clinical data are growing. Analyses of these voluminous, multivariate data sets require understanding of pediatric phenotypic data, data science, and genomics. Use of machine learning techniques to aid in biomarker detection have helped decipher background noise from biologically meaningful changes in the data. Further, emerging research suggests that miRNAs may have potential as therapeutic targets for pediatric precision care. Here, we review current miRNA biomarkers of pediatric diseases and studies that have combined machine learning techniques, miRNA-omics, and patient health data to identify novel biomarkers and potential therapeutics for pediatric diseases. IMPACT: In the following review article, we summarized how recent developments in microRNA research may be coupled with machine learning techniques to advance pediatric precision care.

Epigenetic Regulation of the Vascular Endothelium by Angiogenic LncRNAs

The functional properties of the vascular endothelium are diverse and heterogeneous between vascular beds. This is especially evident when new blood vessels develop from a pre-existing closed cardiovascular system, a process termed angiogenesis. Endothelial cells are key drivers of angiogenesis as they undergo a highly choreographed cascade of events that has both exogenous (e.g., hypoxia and VEGF) and endogenous regulatory inputs. Not surprisingly, angiogenesis is critical in health and disease. Diverse therapeutics target proteins involved in coordinating angiogenesis with varying degrees of efficacy. It is of great interest that recent work on non-coding RNAs, especially long non-coding RNAs (lncRNAs), indicates that they are also important regulators of the gene expression paradigms that underpin this cellular cascade. The protean effects of lncRNAs are dependent, in part, on their subcellular localization. For instance, lncRNAs enriched in the nucleus can act as epigenetic modifiers of gene expression in the vascular endothelium. Of great interest to genetic disease, they are undergoing rapid evolution and show extensive inter- and intra-species heterogeneity. In this review, we describe endothelial-enriched lncRNAs that have robust effects in angiogenesis.

A tangled tale of microRNA and cardiac fibrosis

Cardiac fibrosis is important for wound healing, regeneration and producing the extracellular matrix (ECM) that provides the scaffold for cells. In pathological situations, fibroblasts are activated and remodel the ECM. In volume 133, issue 17 of Clinical Science, Yang et al. discovered that the miR-214-3p/NLRC5 axis is important for fibroblast-to-myofibroblast transition (FMT) and ECM remodelling in a pressure overload model of fibrosis [Clin. Sci. (2019) 133(17), 1845-1856]. This discovery helps to explain the complicated regulation of cardiac fibrosis. It also underscores the need for more investigation into the mechanisms of cardiac fibrosis to develop better diagnostic modalities and therapeutic options in heart failure.

Significant Interference with Porcine Epidemic Diarrhea Virus Pandemic and Classical Strain Replication in Small-Intestine Epithelial Cells Using an shRNA Expression Vector

Porcine epidemic diarrhea (PED) re-emerged in China in 2010 and is now widespread. Evidence indicates that highly virulent porcine epidemic diarrhea virus (PEDV) strains belonging to genotype G2 caused a large-scale outbreak of diarrhea. Currently, vaccines derived from PEDV classical strains do not effectively prevent infection by virulent PEDV strains, and no specific drug is available to treat the disease. RNA interference (RNAi) is a novel and effective way to cure a wide range of viruses. We constructed three short hairpin RNA (shRNA)-expressing plasmids (shR-N307, shR-N463, and shR-N1071) directed against nucleocapsid (N) and determined their antiviral activities in intestine epithelial cells infected with a classical CV777 strain and LNCT2. We verified that shR-N307, shR-N463, and shR-N1071 effectively inhibited the expression of the transfected N gene in vitro, comparable to the control shRNA. We further demonstrated the shRNAs markedly reduced PEDV CV777 and LNCT2 replication upon downregulation of N production. Therefore, this study provides a new strategy for the design of antiviral methods against coronaviruses by targeting their processivity factors.

c-Myb regulates transcriptional activation of miR-143/145 in vascular smooth muscle cells

BACKGROUND

MicroRNAs (miR) are small non-coding RNAs that regulate diverse biological functions. The bicistronic gene miR-143/145 determines cell fate and phenotype of vascular smooth muscle cells (VSMC), in part, by destabilizing Elk-1 mRNA. The transcription factor c-Myb also regulates differentiation and proliferation of VSMC, and here we test whether these effects may be mediated by miR-143/145.

METHODS & RESULTS

Flow cytometry of cardiovascular-directed d3.75 embryoid bodies (EBs) isolated smooth muscle progenitors with specific cell surface markers. In c-myb knockout (c-myb -/-) EB, these progenitors manifest low levels of miR-143 (19%; p<0.05) and miR-145 (6%; p<0.01) expression as compared to wild-type (wt) EB. Primary VSMC isolated from transgenic mice with diminished expression (c-myblx/lx) or reduced activity (c-mybh/h) of c-Myb also manifest low levels of miR-143 (c-myblx/lx: 50%; c-mybh/h: 41%), and miR-145 (c-myblx/lx: 49%; c-mybh/h: 56%), as compared to wt (P<0.05). Sequence alignment identified four putative c-Myb binding sites (MBS1-4) in the proximal promoter (PP) of the miR-143/145 gene. PP-reporter constructs revealed that point mutations in MBS1 and MBS4 abrogated c-Myb-dependent transcription from the miR-143/145 PP (P<0.01). Chromatin immunoprecipitation (ChIP) revealed preferential c-Myb binding at MBS4 (p<0.001). By conjugating Elk-1 3'-untranslated region (UTR) to a reporter and co-transducing wt VSMC with this plus a miR-143-antagomir, and co-transducing c-myblx/lx VSMC with this plus a miR-143-mimic, we demonstrate that c-Myb's ability to repress Elk-1 is mediated by miR-143.

CONCLUSION

c-Myb regulates VSMC gene expression by transcriptional activation of miR-143/145.

Application of cationized magnetoferritin for magnetic field-assisted delivery of short interfering RNA in vitro

Cationized magnetoferritin is used for development of a simple, efficient, and fast delivery of short interference RNA into cells using combination of magnetophoresis for pre-concentration of siRNA-magnetoferritin complex on the surface of plated cells with subsequent application of nanosecond laser pulses producing stress waves in transfection chamber, which permeabilize cell membrane for the facilitated delivery of siRNA into the cell interior. As has been quantified using siRNA inducing cell death assay, by combination of these two physical factors we have obtained high efficiency for tested three different human carcinoma cells. Proposed method of gene silencing based on cationized magnetoferritin is a versatile and easily accessible platform with many possible applications in gene therapy.

Emerging potential of gene silencing approaches targeting anti-chondrogenic factors for cell-based cartilage repair

The field of cartilage repair has exponentially been growing over the past decade. Here, we discuss the possibility to achieve satisfactory regeneration of articular cartilage by means of human mesenchymal stem cells (hMSCs) depleted of anti-chondrogenic factors and implanted in the site of injury. Different types of molecules including transcription factors, transcriptional co-regulators, secreted proteins, and microRNAs have recently been identified as negative modulators of chondroprogenitor differentiation and chondrocyte function. We review the current knowledge about these molecules as potential targets for gene knockdown strategies using RNA interference (RNAi) tools that allow the specific suppression of gene function. The critical issues regarding the optimization of the gene silencing approach as well as the delivery strategies are discussed. We anticipate that further development of these techniques will lead to the generation of implantable hMSCs with enhanced potential to regenerate articular cartilage damaged by injury, disease, or aging.

Epigenetic determinants of cardiovascular gene expression: vascular endothelium

The modern landscape of gene regulation involves interacting factors that ultimately lead to gene activation or repression. Epigenetic mechanisms provide a perspective of cellular phenotype as dynamically regulated and responsive to input. This perspective is supported by the generation of induced pluripotent stem cells from fully differentiated cell types. In vascular endothelial cells, evidence suggests that epigenetic mechanisms play a major role in the expression of endothelial cell-specific genes such as the endothelial nitric oxide synthase (NOS3/eNOS). These mechanisms are also important for eNOS expression in response to environmental stimuli such as hypoxia and shear stress. A newer paradigm in epigenetics, long noncoding RNAs offer a link between genetic variation, epigenetic regulation and disease. While the understanding of epigenetic mechanisms is early in its course, it is becoming clear that approaches to understanding the interaction of these factors and their inputs will be necessary to improve outcomes in cardiovascular disease.

Specific interference shRNA-expressing plasmids inhibit Hantaan virus infection in vitro and in vivo

AIM

To investigate the antiviral effects of vectors expressing specific short hairpin RNAs (shRNAs) against Hantaan virus (HTNV) infection in vitro and in vivo.

METHODS

Based on the effects of 4 shRNAs targeting different regions of HTNV genomic RNA on viral replication, the most effective RNA interference fragments of the S and M genes were constructed in pSilencer-3.0-H1 vectors, and designated pSilencer-S and pSilencer-M, respectively. The antiviral effect of pSilencer-S/M against HTNV was evaluated in both HTNV-infected Vero-E6 cells and mice.

RESULTS

In HTNV-infected Vero-E6 cells, pSilencer-S and pSilencer-M targeted the viral nucleocapsid proteins and envelope glycoproteins, respectively, as revealed in the immunofluorescence assay. Transfection with pSilencer-S or pSilencer-M (1, 2, 4 μg) markedly inhibited the viral antigen expression in dose- and time-dependent manners. Transfection with either plasmid (2 μg) significantly decreased HTNV-RNA level at 3 day postinfectin (dpi) and the progeny virus titer at 5 dpi. In mice infected with lethal doses of HTNV, intraperitoneal injection of pSilencer-S or pSilencer-M (30 μg) considerably increased the survival rates and mean time to death, and significantly reduced the mean virus yields and viral RNA level, and alleviated virus-induced pathological lesions in lungs, brains and kidneys.

CONCLUSION

Plasmid-based shRNAs potently inhibit HTNV replication in vitro and in vivo. Our results provide a basis for development of shRNA as therapeutics for HTNV infections in humans.

The Pharmacological and Physiological Role of Multidrug-Resistant Protein 4

Multidrug-resistant protein 4 (MRP4), a member of the C subfamily of ATP-binding cassette transporters, is distributed in a variety of tissues and a number of cancers. As a drug transporter, MRP4 is responsible for the pharmacokinetics and pharmacodynamics of numerous drugs, especially antiviral drugs, antitumor drugs, and diuretics. In this regard, the functional role of MRP4 is affected by a number of factors, such as genetic mutations; tissue-specific transcriptional regulations; post-transcriptional regulations, including miRNAs and membrane internalization; and substrate competition. Unlike other C family members, MRP4 is in a pivotal position to transport cellular signaling molecules, through which it is tightly connected to the living activity and physiologic processes of cells and bodies. In the context of several cancers in which MRP4 is overexpressed, MRP4 inhibition shows striking effects against cancer progression and drug resistance. In this review, we describe the role of MRP4 more specifically in both healthy conditions and disease states, with an emphasis on its potential as a drug target.

Clinical Pharmacology & Therapeutics: the next five years

It has been nearly ten years since we joined the editorial organization of Clinical Pharmacology & Therapeutics (CPT), as part of the American Society for Clinical Pharmacology and Therapeutics (ASCPT) family. During that tenure, the primary mandate has been the growth of CPT, recognized as one of the key voices of the discipline and the Society. Set goals were realized in concert with a strong editorial team, a diverse editorial board, a dedicated editorial staff, and outstanding authors, leveraging a leading publishing infrastructure and responding to the needs of a global readership, expanding membership, and the discipline as a whole. The impending decade anniversary, and the transition to a new publisher, offers a natural juncture to reflect on progress, and chart plans for the future of the Journal.