Therapeutic evaluation of microRNAs by molecular imaging

MicroRNA-27b Impairs Nrf2-Mediated Angiogenesis in the Progression of Diabetic Foot Ulcer

Nuclear factor erythroid-2-related factor 2 (Nrf2) is a stress-activated transcription factor regulating antioxidant genes, and a deficiency thereof, slowing lymphangiogenesis, has been reported in diabetic foot ulcer (DFU). The mode of Nrf2 regulation in DFU has been less explored. Emerging studies on miRNA-mediated target regulation show miRNA to be the leading player in the pathogenesis of the disease. In the present study, we demonstrated the role of miR-27b in regulating Nrf2-mediated angiogenesis in DFU. A lower expression of mRNA targets, such as Nrf2, HO-1, SDF-1α, and VEGF, was observed in tissue biopsied from chronic DFU subjects, which was in line with miR-27b, signifying a positive correlation with Nrf2. Similarly, we found significantly reduced expression of miR-27b and target mRNAs Nrf2, HO-1, SDF-1α, and VEGF in endothelial cells under a hyperglycemic microenvironment (HGM). To confirm the association of miR-27b on regulating Nrf2-mediated angiogenesis, we inhibited its expression through RNA interference-mediated knockdown and observed disturbances in angiogenic signaling with reduced endothelial cell migration. In addition, to explore the role of miR-27b and angiogenesis in the activation of Nrf2, we pretreated the endothelial cells with two well-known pharmacological compounds-pterostilbene and resveratrol. We observed that activation of Nrf2 through these compounds ameliorates impaired angiogenesis on HGM-induced endothelial cells. This study suggests a positive role of miR-27b in regulating Nrf2, which seems to be decreased in DFU and improves on treatment with pterostilbene and resveratrol.

Bioluminescence Imaging Applications in Cancer: A Comprehensive Review

Bioluminescence imaging (BLI), an optical preclinical imaging modality, is an invaluable imaging modality due to its low-cost, high throughput, fast acquisition times, and functional imaging capabilities. BLI is being extensively used in the field of cancer imaging, especially with the recent developments in genetic-engineering, stem cell, and gene therapy treatments. The purpose of this paper is to provide a comprehensive review of the principles, developments, and current status of BLI in cancer research. This paper covers the fundamental BLI concepts including BLI reporters and enzyme-substrate systems, data acquisition, and image characteristics. It reviews the studies discussing the use of BLI in cancer research such as imaging tumor-characteristic phenomena including tumorigenesis, metastasis, cancer metabolism, apoptosis, hypoxia, and angiogenesis, and response to cancer therapy treatments including chemotherapy, radiotherapy, immunotherapy, gene therapy, and stem cell therapy. The key advantages and disadvantages of BLI compared to other common imaging modalities are also discussed.

Genetically Encoded Reporter Genes for MicroRNA Imaging in Living Cells and Animals

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression by base paring with the complementary sequences of the target mRNAs, and then exert their function through degrading mRNA or inhibiting protein translation. They play a significant role as a regulatory factor in biological processes of organism development, cell proliferation, differentiation, and cell death. Some of the traditional methods for studying miRNAs, such as northern blot, real-time PCR, or microarray, have been extensively used to investigate the biological properties and expression patterns of miRNAs. However, these methods often require considerable time, cell samples, and the design of effective primers or specific probes. Therefore, in order to gain a deeper understanding of the role of miRNAs in biological processes and accelerate the clinical application of miRNAs in the field of disease treatment, non-invasive, sensitive, and efficient imaging methods are needed to visualize the dynamic expression of miRNAs in living cells and animals. In this study, we reviewed the recent progress in the genetically encoded reporter genes for miRNA imaging.

Bioluminescence Imaging for Monitoring miR-200c Expression in Breast Cancer Cells and its Effects on Epithelial-Mesenchymal Transition Progress in Living Animals

PURPOSE

Dysregulation of microRNAs (miRNAs) are not only involved in the formation of malignant tumors but also in the processes of differentiation and aggressiveness. However, current methods for detecting miRNA expression have major disadvantages, such as being invasive and non-reproducible. The epithelial-mesenchymal transition (EMT) has been implicated as a pivotal event in the metastasis, stemness, and chemoresistance of malignant tumors.

PROCEDURES

In our study, we constructed a new reporter gene, Luc2/tdT_miR200c_3TS, to examine the in vitro and in vivo expression of miR-200c, an EMT-associated miRNA. Quantitative real-time PCR was used to measure the expression levels of miR-200c and EMT-related mRNA, and luciferase assay and bioluminescence imaging were used to measure the luciferase activities in vitro and in vivo, respectively.

RESULTS

We found that the expression level of miR-200c was negatively associated with cell migration and invasion. Luciferase activities were regulated by the differential expression levels of miR-200c and EMT process.

CONCLUSIONS

Our results demonstrate that Luc2/tdT_miR200c_3TS may be a useful tool for monitoring the expression level of miR-200c at both the cellular level and in living animals, thereby providing a potential high-throughput approach for anticancer drug screening.

Intracellular MicroRNA Quantification in Intact Cells: A Novel Strategy based on Reduced Graphene Oxide Based Fluorescence Quenching

Nanomaterials have been proposed as key components in biosensing, imaging, and drug-delivery since they offer distinctive advantages over conventional approaches. The unique chemical and physical properties of graphene make it possible to functionalize and develop protein transducers, therapeutic delivery vehicles, and microbial diagnostics. In this study we evaluate reduced graphene oxide (rGO) as a potential nanomaterial for quantification of microRNAs including their structural differentiation in vitro in solution and inside intact cells. Our results provide evidence for the potential use of graphene nanomaterials as a platform for developing devices that can be used for microRNA quantitation as biomarkers for clinical applications.

Modulating microRNAs as Novel Therapeutic Targets in Cardiac Fibrosis

This commentary highlights the findings by Tao et al. (Theranostics 2016; 6: 2068-2083) that targeting miR-433 may be a potential therapeutic strategy for myocardial fibrosis and subsequently discusses the obstacles and prospects associated with the application of therapeutic microRNAs in anti-fibrosis treatment.

Positive radionuclide imaging of miRNA expression using RILES and the human sodium iodide symporter as reporter gene is feasible and supports a protective role of miRNA-23a in response to muscular atrophy

MicroRNAs (miRNAs) are key players in many biological processes and are considered as an emerging class of pharmacology drugs for diagnosis and therapy. However to fully exploit the therapeutic potential of miRNAs, it is becoming crucial to monitor their expression pattern using medical imaging modalities. Recently, we developed a method called RILES, for RNAi-Inducible Luciferase Expression System that relies on an engineered regulatable expression system to switch-ON the expression of the luciferase gene when a miRNA of interest is expressed in cells. Here we investigated whether replacing the luciferase reporter gene with the human sodium iodide symporter (hNIS) reporter gene will be also suited to monitor the expression of miRNAs in a clinical setting context. We provide evidence that radionuclide imaging of miRNA expression using hNIS is feasible although it is not as robust as when the luciferase reporter gene is used. However, under appropriate conditions, we monitored the expression of several miRNAs in cells, in the liver and in the tibialis anterior muscle of mice undergoing muscular atrophy. We demonstrated that radiotracer accumulation in transfected cells correlated with the induction of hNIS and with the expression of miRNAs detected by real time PCR. We established the kinetic of miRNA-23a expression in mice and demonstrated that this miRNA follows a biphasic expression pattern characterized by a loss of expression at a late time point of muscular atrophy. At autopsy, we found an opposite expression pattern between miRNA-23a and one of the main transcriptional target of this miRNA, APAF-1, and as downstream target, Caspase 9. Our results report the first positive monitoring of endogenously expressed miRNAs in a nuclear medicine imaging context and support the development of additional work to establish the potential therapeutic value of miRNA-23 to prevent the damaging effects of muscular atrophy.

Downregulation of microRNA-145 promotes epithelial-mesenchymal transition via regulating Snail in osteosarcoma

Metastasis is the principal cause of cancer death and occurs through multiple, complex processes. Epithelial to mesenchymal transition (EMT) is an important process during embryonic development and has also been hypothesized to exhibit a significant role in cancer cell invasion and metastasis. MicroRNAs (miRNAs) are a class of widespread noncoding RNAs. In recent years, many studies have shown that miRNAs could influence the signaling pathways and downstream events that define EMT on a molecular level. However, the exact role and mechanisms of miR-145 in EMT of osteosarcoma (OS) was unknown. In the present study, miR-145 was downregulated in OS tissues and cell lines and it was shown that miR-145 expression was closely correlated with advanced tumor progression in patients of OS. In addition, miR-145 upregulation by miR-145 agomir significantly inhibited MG63 cells invasion and migration ability. MiR-145 was reported to be able to inhibit EMT in cancers. Following the examination of changes in cell epithelial and mesenchymal markers, it was found that upregulation of miR-145 strongly reversed EMT in MG63 cells. Meanwhile, the expression of Snail, a strong E-cadherin transcription repressor was also attenuated by miR-145 agomir. Furthermore, the decreased EMT and invasion and metastasis caused by miR-145 agomir could be restored by Snail siRNA. In conclusion, the results demonstrated that miR-145 could mediate EMT by targeting Snail and miR-145 might be a novel EMT regulating transcription factor that involved in the progression of OS. The specific drugs targeting miR-145-mediated EMT process might be new promising cancer therapies.

MiR-424-5p participates in esophageal squamous cell carcinoma invasion and metastasis via SMAD7 pathway mediated EMT

Backgrounds

ESCC is a life-threatening disease due to invasion and metastasis in the early stage. Great efforts had been made to detect the molecular mechanisms which led to the invasion and metastasis in ESCC. Recent evidence had suggested that deregulation of miR-424-5p took an important role in cancers. However, its role and functional mechanism in ESCC had seldom been elucidated.

Methods

The expression levels of miR-424-5p were detected in ESCC tissues and cell lines by real-time PCR methods. Then, the invasion, metastasis and proliferation ability of ESCC cell lines transfected with miR-424-5p mimics were analyzed separately by transwell invasion assay, wound healing assay and cell proliferation assay. Finally, the target gene of miR-424-5p was studied and verified by luciferase activity assay. And the role of miR-424-5p in EMT was also investigated by real-time PCR and western blot assay.

Results

We showed that the expression levels of miR-424-5p were decreased both in ESCC tissues and cell lines. Furthermore, the expression levels of miR-424-5p were negatively linked to lymph node metastasis in ESCC tissues. Restoration of miR-424-5p in EC-1 cells by using miR-424-5p mimics could decrease the invasion, metastasis and proliferation of EC-1 cells, indicating its role in inhibition on the invasion and metastasis ability of ESCC cells and tissues. In addition, we demonstrated that SMAD7 was a specific target gene for miR-424-5p by luciferase activity assay and miR-424-5p could not only negatively regulate SMAD7 expression but also participate in EMT via SMAD7, because overexpression of SMAD7 could partly enhance the miR-424-5p anti-EMT function.

Conclusions

Our results described that miR-424-5p -SMAD7 pathway contributed to ESCC invasion and metastasis and up-regulation of miR-424-5p perhaps provided a strategy for preventing tumor invasion, metastasis.

Noninvasive visualization of microRNA-155 in multiple kinds of tumors using a radiolabeled anti-miRNA oligonucleotide

PURPOSE

We investigated whether a (99m)Tc radiolabeled anti-miRNA-155 oligonucleotide (AMO-155) could visualize the expression of miR-155 in multiple kinds of tumors in vivo.

METHODS

AMO-155 was chemically synthesized and modified with 2'-O-methyl (2'-OMe) and phosphorothioate (PS). It was radiolabeled with (99m)Tc via the conjugation with NHS-MAG3 at 5' end. The characterization of radiolabeling and serum stability was evaluated using high performance liquid chromatography (HPLC) and agarose gel electrophoresis. The expression of C/EBPβ, one of the miR-155 target proteins, was assessed using Western blot. The cellular uptake and delivery of AMO-155 was further evaluated in tumor cells. (99m)Tc-AMO-155 was tested in vivo in multiple tumor models, including miR-155 over-expressed and low-expressed tumor models. Finally, biodistribution of (99m)Tc-AMO-155 was evaluated.

RESULTS

(99m)Tc-AMO-155 was prepared with high yield and radiochemical purity. It showed high stability in fresh human serum for 10h. (99m)Tc-AMO-155 displayed comparable capacity as unlabeled AMO-155 to increase the expression of C/EBPβ protein in MCF-7 cells. (99m)Tc-AMO-155 showed an increased radioactive uptake in MCF-7 cells after 8h of incubation, whereas no change of (99m)Tc-pertechnetate uptake was observed. Carboxyfluorescein (FAM) labeled AMO-155 had higher fluorescent delivery than Control in HeLa and HepG2 cells by confocal microscopy. In miR-155 over-expressed tumor models, (99m)Tc-AMO-155 showed significantly higher tumor accumulation than (99m)Tc-Control. Furthermore, (99m)Tc-AMO-155 was capable of discriminating between MCF-7 and MDA-MB-231 tumors based on their expression of miR-155.

CONCLUSIONS

Our study successfully prepared and proved (99m)Tc-AMO-155 as a prospective imaging agent for the noninvasive visualization of miR-155 expression in vivo.

MicroRNA-129-1 acts as tumour suppressor and induces cell cycle arrest of GBM cancer cells through targeting IGF2BP3 and MAPK1

BACKGROUND

MicroRNA-129-1 (miR-129-1) seems to behave as a tumour suppressor since its decreased expression is associated with different tumours such as glioblastoma multiforme (GBM). GBM is the most common form of brain tumours originating from glial cells. The impact of miR-129-1 downregulation on GBM pathogenesis has yet to be elucidated.

METHODS

MiR-129-1 was overexpressed in GBM cells, and its effect on proliferation was investigated by cell cycle assay. MiR-129-1 predicted targets (CDK6, IGF1, HDAC2, IGF2BP3 and MAPK1) were also evaluated by western blot and luciferase assay.

RESULTS

Restoration of miR-129-1 reduced cell proliferation and induced G1 accumulation, significantly. Several functional assays confirmed IGF2BP3, MAPK1 and CDK6 as targets of miR-129-1. Despite the fact that IGF1 expression can be suppressed by miR-129-1, through 3'-untranslated region complementary sequence, we could not find any association between IGF1 expression and GBM. MiR-129-1 expression inversely correlates with CDK6, IGF2BP3 and MAPK1 in primary clinical samples.

CONCLUSION

This is the first study to propose miR129-1 as a negative regulator of IGF2BP3 and MAPK1 and also a cell cycle arrest inducer in GBM cells. Our data suggests miR-129-1 as a potential tumour suppressor and presents a rationale for the use of miR-129-1 as a novel strategy to improve treatment response in GBM.

MIR137 Regulates Starvation-Induced Autophagy by Targeting ATG7

Autophagy is a cellular catabolic mechanism in response to stress conditions and has been implicated in the progression and chemoresistance of various cancers. Human microR-137 (MIR137) is involved in neuronal maturation and neurogenesis, while little is known about its role in cancer. In this study, we showed that starvation increased the formation of autophagic marker microtubule-associated protein 1 light chain 3 (LC3) without significant change of MIR137 level in U87 cells. In addition, overexpression of MIR137 decreased LC3 expression and inhibited the degradation of the autophagy receptor sequestosome 1(SQSTM1/p62), while the MIR137 antagomirs showed the opposite effect on these autophagic markers. Moreover, MIR137 overexpression decreased, while its antagomirs increased the expression of autophagy-related 7(ATG7) mRNA and protein. MIR137-mediated inhibition of autophagy was prevented by ATG7. Finally, MIR137 promoted the sensitivity of U87 cells to adriamycin, an anticancer drug. Taken together, our study demonstrated that MIR137 attenuated starvation-induced autophagy by regulating the expression of ATG7.

Polymer nanoparticles mediated codelivery of antimiR-10b and antimiR-21 for achieving triple negative breast cancer therapy

The current study shows the therapeutic outcome achieved in triple negative breast cancer (TNBC) by simultaneously antagonizing miR-21-induced antiapoptosis and miR-10b-induced metastasis, using antisense-miR-21-PS and antisense-miR-10b-PS delivered by polymer nanoparticles (NPs). We synthesized the antisense-miR-21 and antisense-miR-10b loaded PLGA-b-PEG polymer NPs and evaluated their cellular uptake, serum stability, release profile, and the subsequent synchronous blocking of endogenous miR-21 and miR-10b function in TNBC cells in culture, and tumor xenografts in living animals using molecular imaging. Results show that multitarget antagonization of endogenous miRNAs could be an efficient strategy for targeting metastasis and antiapoptosis in the treatment of metastatic cancer. Targeted delivery of antisense-miR-21 and antisense-miR-10b coloaded urokinase plasminogen activator receptor (uPAR) targeted polymer NPs treated mice showed substantial reduction in tumor growth at very low dose of 0.15 mg/kg, compared to the control NPs treated mice and 40% reduction in tumor growth compared to scramble peptide conjugated NPs treated mice, thus demonstrating a potential new therapeutic option for TNBC.

Biomarker-based MicroRNA Therapeutic Strategies for Hepatocellular Carcinoma

Recently, microRNAs (miRNAs) have emerged as key factors involved in a series of biological processes, ranging from embryogenesis to programmed cell death. Its link to aberrant expression profiles has rendered it a potentially attractive tool for the diagnosis, prognosis, or treatment of various diseases. Accumulating evidence has indicated that miRNAs act as tumor suppressors in hepatocyte malignant transformation by regulating development, differentiation, proliferation, and tumorigenesis. Here, we summarize recent progress in the development of novel biomarker-based miRNA therapeutic strategies for hepatocellular carcinoma (HCC).

Gene therapy and imaging in preclinical and clinical oncology: recent developments in therapy and theranostics

In the case of disseminated cancer, current treatment options reach their limit. Gene theranostics emerge as an innovative route in the treatment and diagnosis of cancer and might pave the way towards development of an efficacious treatment of currently incurable cancer. Various gene vectors have been developed to realize tumor-specific nucleic acid delivery and are considered crucial for the successful application of cancer gene therapy. By adding reporter genes and imaging agents, these systems gain an additional diagnostic function, thereby advancing the theranostic paradigm into cancer gene therapy. Numerous preclinical studies have demonstrated the feasibility of combined tumor gene therapy and diagnostic imaging, and clinical trials in human and veterinary oncology have been executed with partly encouraging results.

Biomarker-based MicroRNA Therapeutic Strategies for Hepatocellular Carcinoma

Recently, microRNAs (miRNAs) have emerged as key factors involved in a series of biological processes, ranging from embryogenesis to programmed cell death. Its link to aberrant expression profiles has rendered it a potentially attractive tool for the diagnosis, prognosis, or treatment of various diseases. Accumulating evidence has indicated that miRNAs act as tumor suppressors in hepatocyte malignant transformation by regulating development, differentiation, proliferation, and tumorigenesis. Here, we summarize recent progress in the development of novel biomarker-based miRNA therapeutic strategies for hepatocellular carcinoma (HCC).

MicroRNAs in Schizophrenia: Implications for Synaptic Plasticity and Dopamine-Glutamate Interaction at the Postsynaptic Density. New Avenues for Antipsychotic Treatment Under a Theranostic Perspective

Despite dopamine-glutamate aberrant interaction that has long been considered a relevant landmark of psychosis pathophysiology, several aspects of these two neurotransmitters reciprocal interaction remain to be defined. The emerging role of postsynaptic density (PSD) proteins at glutamate synapse as a molecular "lego" making a functional hub where different signals converge may add a new piece of information to understand how dopamine-glutamate interaction may work with regard to schizophrenia pathophysiology and treatment. More recently, compelling evidence suggests a relevant role for microRNA (miRNA) as a new class of dopamine and glutamate modulators with regulatory functions in the reciprocal interaction of these two neurotransmitters. Here, we aimed at addressing the following issues: (i) Do miRNAs have a role in schizophrenia pathophysiology in the context of dopamine-glutamate aberrant interaction? (ii) If miRNAs are relevant for dopamine-glutamate interaction, at what level this modulation takes place? (iii) Finally, will this knowledge open the door to innovative diagnostic and therapeutic tools? The biogenesis of miRNAs and their role in synaptic plasticity with relevance to schizophrenia will be considered in the context of dopamine-glutamate interaction, with special focus on miRNA interaction with PSD elements. From this framework, implications both for biomarkers identification and potential innovative interventions will be considered.

MicroRNAs - a new generation molecular targets for treating cellular diseases

MicroRNAs (miRNAs) are a unique class of non-coding, small RNAs, similar to mRNAs, transcribed by cells, but for entirely different reasons. While mRNAs are transcribed to code for proteins, miRNAs are produced to regulate the production of proteins from mRNAs. miRNAs are central components that tightly and temporally regulating gene expression in cells. Dysregulation of miRNAs expressions in cellular pathogenesis, including cancer, has been reported, and it clearly supports the importance of miRNAs as therapeutic targets in almost every cellular disease. This special issue compiles manuscripts from different authors in order to highlight the importance of microRNAs in cancer and other cellular diseases and how to explore them as therapeutic targets to treat patients with these genetic and metabolic disorders. This issue also covers manuscripts that highlight the obstacles associated with the delivery of therapeutic microRNAs in cells and in vivo in living animals and how to improve and noninvasively monitor the delivery in living animals through molecular imaging, including potential clinical perspectives.