Development of Novel Small Hairpin RNAs That do not Require Processing by Dicer or AGO2

Advanced gene therapy system for the treatment of solid tumour: A review

In contrast to conventional therapies that require repeated dosing, gene therapy can treat diseases by correcting defective genes after a single transfection and achieving cascade amplification, and has been widely studied in clinical settings. However, nucleic acid drugs are prone to catabolism and inactivation. A variety of nucleic acid drug vectors have been developed to protect the target gene against nuclease degradation and increase the transformation efficiency and safety of gene therapy. In addition, gene therapy is often combined with chemotherapy, phototherapy, magnetic therapy, ultrasound, and other therapeutic modalities to improve the therapeutic effect. This review systematically introduces ribonucleic acid (RNA) interference technology, antisense oligonucleotides, and clustered regularly interspaced short palindromic repeat/CRISPR-associated nuclease 9 (CRISPR/Cas9) genome editing. It also introduces the commonly used nucleic acid drug vectors, including viral vectors (adenovirus, retrovirus, etc.), organic vectors (lipids, polymers, etc.), and inorganic vectors (MOFs, carbon nanotubes, mesoporous silica, etc.). Then, we describe the combined gene therapy modalities and the pathways of action and report the recent applications in solid tumors of the combined gene therapy. Finally, the challenges of gene therapy in solid tumor treatment are introduced, and the prospect of application in this field is presented.

Nuclear microRNAs release paused Pol II via the DDX21-CDK9 complex

RNA activation (RNAa) is an uncharacterized mechanism of transcriptional activation mediated by small RNAs, such as microRNAs (miRNAs). A critical issue in RNAa research is that it is difficult to distinguish between changes in gene expression caused indirectly by post-transcriptional regulation and direct induction of gene expression by RNAa. Therefore, in this study, we seek to identify a key factor involved in RNAa, using the induction of ZMYND10 by miR-34a as a system to evaluate RNAa. We identify the positive transcription elongation factors CDK9 and DDX21, which form a complex with nuclear AGO and TNRC6A, as important transcriptional activators of RNAa. In addition, we find that inhibition of DDX21 suppresses RNAa by miR-34a and other miRNAs without inhibiting post-transcriptional regulation. Our findings reveal a strong connection between RNAa and release of paused Pol II, facilitating RNAa research by making it possible to separately analyze post-transcriptional regulation and RNAa.

LncRNAs and miRs as epigenetic signatures in diabetic cardiac fibrosis: new advances and perspectives

PURPOSE

Diabetic cardiomyopathy (DCM) is a serious cardiac complication of diabetes, which further lead to heartfailure. It is known that diabetes-induced cardiac fibrosis is a key pathogenic factor contributing topathological changes in DCM. However, pathogenetic mechanisms underlying diabetes cardiac fibrosis arestill elusive. Recent studies have indicated that noncoding RNAs (ncRNAs) play a key role in diabetescardiac fibrosis. The increasing complexity of epigenetic regulator poses great challenges to ourconventional conceptions regarding how ncRNAs regulate diabetes cardiac fibrosis.

METHODS

We searched PubMed, Web of Science, and Scopus for manuscripts published prior to April 2018 using keywords "Diabetic cardiomyopathy" AND " diabetes cardiac fibrosis " OR " noncoding RNAs " OR " longnoncoding RNAs " OR " microRNAs " OR "epigenetic". Manuscripts were collated, studied and carriedforward for discussion where appropriate.

RESULTS

Based on the view that during diabetic cardiac fibrosis, ncRNAs are able to regulate diabetic cardiac fibrosisby targeting genes involved in epigenetic pathways. Many studies have focused on ncRNAs, an epigeneticregulator deregulating protein-coding genes in diabetic cardiac fibrosis, to identify potential therapeutictargets. Recent advances and new perspectives have found that long noncoding RNAs and microRNAs,exert their own effects on the progression of diabetic cardiac fibrosis.

CONCLUSION

We firstly examine the growing role of ncRNAs characteristics and ncRNAs-regulated genes involved indiabetic cardiac fibrosis. Then, we provide several possible therapeutic strategies and highlight the potentialof molecular mechanisms in which targeting epigenetic regulators are considered as an effective means of treating diabetic cardiac fibrosis.

Comprehensive Evolutionary Analysis of the Major RNA-Induced Silencing Complex Members

RNA-induced silencing complex (RISC) plays a critical role in small interfering RNA (siRNA) and microRNAs (miRNA) pathways. Accumulating evidence has demonstrated that the major RISC members (AGO, DICER, TRBP, PACT and GW182) represent expression discrepancies or multiple orthologues/paralogues in different species. To elucidate their evolutionary characteristics, an integrated evolutionary analysis was performed. Here, animal and plant AGOs were divided into three classes (multifunctional AGOs, siRNA-associated AGOs and piRNA-associated AGOs for animal AGOs and multifunctional AGOs, siRNA-associated AGOs and complementary functioning AGOs for plant AGOs). Animal and plant DICERs were grouped into one class (multifunctional DICERs) and two classes (multifunctional DICERs and siRNA-associated DICERs), respectively. Protista/fungi AGOs or DICERs were specifically associated with the siRNA pathway. Additionally, TRBP/PACT/GW182 were identified only in animals, and all of them functioned in the miRNA pathway. Mammalian AGOs, animal DICERs and chordate TRBP/PACT were found to be monophyletic. A large number of gene duplications were identified in AGO and DICER groups. Taken together, we provide a comprehensive evolutionary analysis, describe a phylogenetic tree-based classification of the major RISC members and quantify their gene duplication events. These findings are potentially useful for classifying RISCs, optimizing species-specific RISCs and developing research model organisms.

Dicer-independent processing of small RNA duplexes: mechanistic insights and applications

MicroRNAs (miRNAs) play a pivotal role in the regulation of cellular gene expression via the conserved RNA interference (RNAi) mechanism. Biogenesis of the unusual miR-451 does not require Dicer. This molecule is instead processed by the Argonaute 2 (Ago2) enzyme. Similarly, unconventional short hairpin RNA (shRNA) molecules have been designed as miR-451 mimics that rely exclusively on Ago2 for maturation. We will review recent progress made in the understanding of this alternative processing route. Next, we describe different Dicer-independent shRNA designs that have been developed and discuss their therapeutic advantages and disadvantages. As an example, we will present the route towards development of a durable gene therapy against HIV-1.

MicroRNA-34a: A Versatile Regulator of Myriads of Targets in Different Cancers

MicroRNA-34a (miR-34a) is a tumor suppressor that has attracted considerable attention in recent years. It modulates cancer cell invasion, metastasis, and drug resistance, and has also been evaluated as a diagnostic and/or prognostic biomarker. A number of targets of miR-34a have been identified, including some other non-coding RNAs, and it is believed that the modulation of these myriads of targets underlines the versatile role of miR-34a in cancer progression and pathogenesis. Seemingly appealing results from preclinical studies have advocated the testing of miR-34a in clinical trials. However, the results obtained are not very encouraging and there is a need to re-interpret how miR-34a behaves in a context dependent manner in different cancers. In this review, we have attempted to summarize the most recent evidence related to the regulation of different genes and non-coding RNAs by miR-34a and the advances in the field of nanotechnology for the targeted delivery of miR-34a-based therapeutics and mimics. With the emergence of data that contradicts miR-34a’s tumor suppressive function, it is important to understand miR-34a’s precise functioning, with the aim to establish its role in personalized medicine and to apply this knowledge for the identification of individual patients that are likely to benefit from miR-34a-based therapy.

Nano-based delivery of RNAi in cancer therapy

Background

RNA interference (RNAi), a newly developed method in which RNA molecules inhibit gene expression, has recently received considerable research attention. In the development of RNAi-based therapies, nanoparticles, which have distinctive size effects along with facile modification strategies and are capable of mediating effective RNAi with targeting potential, are attracting extensive interest.

Objective

This review presents an overview of the mechanisms of RNAi molecules in gene therapy and the different nanoparticles used to deliver RNAi molecules; briefly describes the current uses of RNAi in cancer therapy along with the nano-based delivery of RNA molecules in previous studies; and highlights some other carriers that have been applied in clinical settings. Finally, we discuss the nano-based delivery of RNAi therapeutics in preclinical development, including the current status and limitations of anti-cancer treatment.

Conclusion

With the growing number of RNAi therapeutics entering the clinical phase, various nanocarriers are expected to play important roles in the delivery of RNAi molecules for cancer therapeutics.