miR-20a encoded by the miR-17-92 cluster increases the metastatic potential of osteosarcoma cells by regulating Fas expression

miRNA-214-3p stimulates carcinogen-induced mammary epithelial cell apoptosis in mammary cancer-resistant species

Mammary cancer incidence varies greatly across species and underlying mechanisms remain elusive. We previously showed that mammosphere-derived epithelial cells from species with low mammary cancer incidence, such as horses, respond to carcinogen 7, 12-Dimethylbenz(a)anthracene-induced DNA damage by undergoing apoptosis, a postulated anti-cancer mechanism. Additionally, we found that miR-214-3p expression in mammosphere-derived epithelial cells is lower in mammary cancer-resistant as compared to mammary cancer-susceptible species. Here we show that increasing miR-214 expression and decreasing expression of its target gene nuclear factor kappa B subunit 1 in mammosphere-derived epithelial cells from horses abolishes 7,12-Dimethylbenz(a)anthracene-induced apoptosis. A direct interaction of miR-214-3p with another target gene, unc-5 netrin receptor A, is also demonstrated. We propose that relatively low levels of miR-214 in mammosphere-derived epithelial cells from mammals with low mammary cancer incidence, allow for constitutive gene nuclear factor kappa B subunit 1 expression and apoptosis in response to 7, 12-Dimethylbenz(a)anthracene. Better understanding of the mechanisms regulating cellular responses to carcinogens improves our overall understanding of mammary cancer resistance mechanisms.

The Role of FAS Receptor Methylation in Osteosarcoma Metastasis

Osteosarcoma is the most frequent primary malignant bone tumor with an annual incidence of about 400 cases in the United States. Osteosarcoma primarily metastasizes to the lungs, where FAS ligand (FASL) is constitutively expressed. The interaction of FASL and its cell surface receptor, FAS, triggers apoptosis in normal cells; however, this function is altered in cancer cells. DNA methylation has previously been explored as a mechanism for altering FAS expression, but no variability was identified in the CpG island (CGI) overlapping the promoter. Analysis of an expanded region, including CGI shores and shelves, revealed high variability in the methylation of certain CpG sites that correlated significantly with FAS mRNA expression in a negative manner. Bisulfite sequencing revealed additional CpG sites, which were highly methylated in the metastatic LM7 cell line but unmethylated in its parental non-metastatic SaOS-2 cell line. Treatment with the demethylating agent, 5-azacytidine, resulted in a loss of methylation in CpG sites located within the FAS promoter and restored FAS protein expression in LM7 cells, resulting in reduced migration. Orthotopic implantation of 5-azacytidine treated LM7 cells into severe combined immunodeficient mice led to decreased lung metastases. These results suggest that DNA methylation of CGI shore sites may regulate FAS expression and constitute a potential target for osteosarcoma therapy, utilizing demethylating agents currently approved for the treatment of other cancers.

Cracking the code: Deciphering the role of the tumor microenvironment in osteosarcoma metastasis

Osteosarcoma (OS) is the most common malignant bone tumor in children and adolescents. It is characterized by a rapid progression, poor prognosis, and early pulmonary metastasis. Over the past 30 years, approximately 85% of patients with osteosarcoma have experienced metastasis. The five-year survival of patients with lung metastasis during the early stages of treatment is less than 20%. The tumor microenvironment (TME) not only provides conditions for tumor cell growth but also releases a variety of substances that can promote the metastasis of tumor cells to other tissues and organs. Currently, there is limited research on the role of the TME in osteosarcoma metastasis. Therefore, to explore methods for regulating osteosarcoma metastasis, further investigations must be conducted from the perspective of the TME. This will help to identify new potential biomarkers for predicting osteosarcoma metastasis and assist in the discovery of new drugs that target regulatory mechanisms for clinical diagnosis and treatment. This paper reviews the research progress on the mechanism of osteosarcoma metastasis based on TME theory, which will provide guidance for the clinical treatment of osteosarcoma.

The potential role of miRNAs in the pathogenesis of salivary gland cancer - A Focus on signaling pathways interplay

Salivary gland cancer (SGC) is immensely heterogeneous, both in terms of its physical manifestation and its aggressiveness. Developing a novel diagnostic and prognostic detection method based on the noninvasive profiling of microribonucleic acids (miRs) could be a goal for the clinical management of these specific malignancies, sparing the patients' valuable time. miRs are promising candidates as prognostic biomarkers and therapeutic targets or factors that can advance the therapy of SGC due to their ability to posttranscriptionally regulate the expression of various genes involved in cell proliferation, differentiation, cell cycle, apoptosis, invasion, and angiogenesis. Depending on their biological function, many miRs may contribute to the development of SGC. Therefore, this article serves as an accelerated study guide for SGC and the biogenesis of miRs. Here, we shall list the miRs whose function in SGC pathogenesis has recently been determined with an emphasis on their potential applications as therapeutic targets. We will also offer a synopsis of the current state of knowledge about oncogenic and tumor suppressor miRs in relation to SGC.

Pramlintide: A Novel Therapeutic Approach for Osteosarcoma through Metabolic Reprogramming

Despite aggressive combination chemotherapy and surgery, outcomes for patients with osteosarcoma have remained stagnant for more than 25 years, and numerous clinical trials have identified no new therapies. p53 deletion or mutation is found in more than 80% of osteosarcoma tumors. In p53-deficient cancers with structurally altered p63 and p73, interfering with tumor cell metabolism using Pramlintide (an FDA-approved drug for type 2 diabetes) results in tumor regression. Pramlintide response is mediated through upregulation of islet amyloid polypeptide (IAPP). Here, we showed that osteosarcoma cells have altered p63, p73, and p53, and decreased IAPP expression but have the two main IAPP receptors, CalcR and RAMP3, which inhibit glycolysis and induce apoptosis. We showed that in osteosarcoma cells with high- or mid-range glycolytic activity, Pramlintide decreased cell glycolysis, resulting in decreased proliferation and increased apoptosis in vitro. In contrast, Pramlintide had no effect in osteosarcoma cells with low glycolytic activity. Using a subcutaneous osteosarcoma mouse model, we showed that intratumoral injection of Pramlintide-induced tumor regression. Tumor sections showed increased apoptosis and a decrease in Ki-67 and HIF-1α. These data suggest that in osteosarcoma cells with altered p53, p63, and p73 and a high glycolytic function, Pramlintide therapy can modulate metabolic programming and inhibit tumor growth.

A new biomarker to enhance the radiosensitivity of hepatocellular cancer: miRNAs

Aims: This review summarizes findings regarding miRNAs that modulate radiation in hepatocellular carcinoma (HCC) and evaluates their potential clinical therapeutic uses. Materials & methods: We searched the relevant English-language medical databases for papers on miRNAs and radiation therapy for tumors to identify miRNAs that are linked with radiosensitivity and radioresistance, focusing on those associated with HCC radiation. Results: There were 88 papers assessed for miRNAs associated with tumor radiation, 56 of which dealt with radiosensitization, 21 with radioresistance and 11 with radiosensitization for HCC. Conclusion: Further work in this area would enable future evaluation of radiation responses and the potential use of miRNAs as therapeutic agents in HCC patients.

Antiapoptotic Protein FAIM2 is targeted by miR-3202, and DUX4 via TRIM21, leading to cell death and defective myogenesis

Inappropriate expression of DUX4, a transcription factor that induces cell death at high levels of expression and impairs myoblast differentiation at low levels of expression, leads to the development of facioscapulohumeral muscular dystrophy (FSHD), however, the pathological mechanisms downstream of DUX4 responsible for muscle loss are poorly defined. We performed a screen of 1972 miR inhibitors for their ability to interfere with DUX4-induced cell death of human immortalized myoblasts. The most potent hit identified by the screen, miR-3202, is known to target the antiapoptotic protein FAIM2. Inhibition of miR-3202 led to the upregulation of FAIM2, and remarkably, expression of DUX4 led to reduced cellular levels of FAIM2. We show that the E3 ubiquitin ligase and DUX4 target gene, TRIM21, is responsible for FAIM2 degradation downstream of DUX4. Human myoblasts overexpressing FAIM2 showed increased resistance to DUX4-induced cell death, whereas in wild-type cells FAIM2 knockdown resulted in increased apoptosis and failure to differentiate into myotubes. The necessity of FAIM2 for myogenic differentiation of WT cells led us to test the effect of FAIM2 overexpression on the impairment of myogenesis by DUX4. Strikingly, FAIM2 overexpression rescued the myogenic differentiation defect caused by low-level expression of DUX4. These data implicate FAIM2 levels, modulated by DUX4 through TRIM21, as an important factor mediating the pathogenicity of DUX4, both in terms of cell viability and myogenic differentiation, and thereby open a new avenue of investigation towards drug targets in FSHD.

MiR-20a-5p Negatively Regulates NR4A3 to Promote Metastasis in Bladder Cancer

Metastasis is the leading cause of death in cancer patients. Therefore, the prediction and treatment of metastasis are critical in improving the survival of patients with bladder cancer. In this study, we aimed to investigate the role of miR-20a-5p and NR4A3 in bladder cancer and the regulatory relationship between them. The high expression of miR-20a-5p in the bladder cancer (BCa) tissues and cells was determined by qRT-PCR. Exogenous miR-20a-5p overexpression promoted the proliferation, migration, and invasion of BCa cells. MiR-20a-5p inhibition inhibited the BCa cell proliferation, invasion, and migration. NR4A3 was proved to be the target gene of miR-20a-5p by the double luciferase reporter assay. In addition, the reduction of NR4A3 could promote the proliferation, invasion, and clonal formation of the bladder cancer cells 5637 and T24. NR4A3 overexpression could reverse the carcinogenic effect of miR-20a. We further confirmed that the oncogenic effect of miR-20a was achieved by promoting EMT in tumor cells. MiR-20a-5p promoted the growth and metastasis of the bladder cancer cells by inhibiting the expression of the tumor suppressor gene NR4A3 and played a carcinogenic role in BCa. Thus, miR-20a-5p may become a potential therapeutic target for BCa treatment.

Noncoding RNAs in apoptosis: identification and function

Apoptosis is a vital cellular process that is critical for the maintenance of homeostasis in health and disease. The derailment of apoptotic mechanisms has severe consequences such as abnormal development, cancer, and neurodegenerative diseases. Thus, there exist complex regulatory mechanisms in eukaryotes to preserve the balance between cell growth and cell death. Initially, protein-coding genes were prioritized in the search for such regulatory macromolecules involved in the regulation of apoptosis. However, recent genome annotations and transcriptomics studies have uncovered a plethora of regulatory noncoding RNAs that have the ability to modulate not only apoptosis but also many other biochemical processes in eukaryotes. In this review article, we will cover a brief summary of apoptosis and detection methods followed by an extensive discussion on microRNAs, circular RNAs, and long noncoding RNAs in apoptosis.

microRNA-based diagnostic and therapeutic applications in cancer medicine

It has been almost two decades since the first link between microRNAs and cancer was established. In the ensuing years, this abundant class of short noncoding regulatory RNAs has been studied in virtually all cancer types. This tremendously large body of research has generated innovative technological advances for detection of microRNAs in tissue and bodily fluids, identified the diagnostic, prognostic, and/or predictive value of individual microRNAs or microRNA signatures as potential biomarkers for patient management, shed light on regulatory mechanisms of RNA-RNA interactions that modulate gene expression, uncovered cell-autonomous and cell-to-cell communication roles of specific microRNAs, and developed a battery of viral and nonviral delivery approaches for therapeutic intervention. Despite these intense and prolific research efforts in preclinical and clinical settings, there are a limited number of microRNA-based applications that have been incorporated into clinical practice. We review recent literature and ongoing clinical trials that highlight most promising approaches and standing challenges to translate these findings into viable microRNA-based clinical tools for cancer medicine. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Multiple interactions between melatonin and non-coding RNAs in cancer biology

The melatonin hormone secreted by the pineal gland is involved in physiological functions such as growth and maturation, circadian cycles, and biological activities including antioxidants, anti-tumor, and anti-ischemia. Melatonin not only interacts with proteins but also has functional effects on regulatory RNAs such as long non-coding RNAs (lncRNAs) and microRNAs (miRNAs). In this study, we overview various physiological and pathological conditions affecting melatonin through lncRNA and miRNA. The information compiled herein will serve as a solid foundation to formulate ideas for future mechanistic studies on melatonin. It will also provide a chance to more clarify the emerging functions of the non-coding transcriptome.

Systematically Studying the Effect of Small Molecules Interacting with RNA in Cellular and Preclinical Models

The interrogation and manipulation of biological systems by small molecules is a powerful approach in chemical biology. Ideal compounds selectively engage a target and mediate a downstream phenotypic response. Although historically small molecule drug discovery has focused on proteins and enzymes, targeting RNA is an attractive therapeutic alternative, as many disease-causing or -associated RNAs have been identified through genome-wide association studies. As the field of RNA chemical biology emerges, the systematic evaluation of target validation and modulation of target-associated pathways is of paramount importance. In this Review, through an examination of case studies, we outline the experimental characterization, including methods and tools, to evaluate comprehensively the impact of small molecules that target RNA on cellular phenotype.

The conserved alternative splicing factor caper regulates neuromuscular phenotypes during development and aging

RNA-binding proteins play an important role in the regulation of post-transcriptional gene expression throughout the nervous system. This is underscored by the prevalence of mutations in genes encoding RNA splicing factors and other RNA-binding proteins in a number of neurodegenerative and neurodevelopmental disorders. The highly conserved alternative splicing factor Caper is widely expressed throughout the developing embryo and functions in the development of various sensory neural subtypes in the Drosophila peripheral nervous system. Here we find that caper dysfunction leads to aberrant neuromuscular junction morphogenesis, as well as aberrant locomotor behavior during larval and adult stages. Despite its widespread expression, our results indicate that caper function is required to a greater extent within the nervous system, as opposed to muscle, for neuromuscular junction development and for the regulation of adult locomotor behavior. Moreover, we find that Caper interacts with the RNA-binding protein Fmrp to regulate adult locomotor behavior. Finally, we show that caper dysfunction leads to various phenotypes that have both a sex and age bias, both of which are commonly seen in neurodegenerative disorders in humans.

Role of miRNA-19a in Cancer Diagnosis and Poor Prognosis

Cancer is a multifactorial disease that affects millions of people every year and is one of the most common causes of death in the world. The high mortality rate is very often linked to late diagnosis; in fact, nowadays there are a lack of efficient and specific markers for the early diagnosis and prognosis of cancer. In recent years, the discovery of new diagnostic markers, including microRNAs (miRNAs), has been an important turning point for cancer research. miRNAs are small, endogenous, non-coding RNAs that regulate gene expression. Compelling evidence has showed that many miRNAs are aberrantly expressed in human carcinomas and can act with either tumor-promoting or tumor-suppressing functions. miR-19a is one of the most investigated miRNAs, whose dysregulated expression is involved in different types of tumors and has been potentially associated with the prognosis of cancer patients. The aim of this review is to investigate the role of miR-19a in cancer, highlighting its involvement in cell proliferation, cell growth, cell death, tissue invasion and migration, as well as in angiogenesis. On these bases, miR-19a could prove to be truly useful as a potential diagnostic, prognostic, and therapeutic marker.

MicroRNA Expression Changes and Integrated Pathways Associated With Poor Outcome in Canine Osteosarcoma

MicroRNAs (miRNA) are small non-coding RNA molecules involved in post-transcriptional gene regulation. Deregulation of miRNA expression occurs in cancer, and miRNA expression profiles have been associated with diagnosis and prognosis in many cancers. Osteosarcoma (OS), an aggressive primary tumor of bone, affects ~10,000 dogs each year. Though survival has improved with the addition of chemotherapy, up to 80% of canine patients will succumb to metastatic disease. Reliable prognostic markers are lacking for this disease. miRNAs are attractive targets of biomarker discovery efforts due to their increased stability in easily obtained body fluids as well as within fixed tissue. Previous studies in our laboratory demonstrated that dysregulation of genes in aggressive canine OS tumors that participate in miRNA regulatory networks is reportedly disrupted in OS or other cancers. We utilized RT-qPCR in a 384-well-plate system to measure the relative expression of 190 miRNAs in 14 canine tumors from two cohorts of dogs with good or poor outcome (disease-free interval >300 or <100 days, respectively). Differential expression analysis in this subset guided the selection of candidate miRNAs in tumors and serum samples from larger groups of dogs. We ultimately identified a tumor-based three-miR Cox proportional hazards regression model and a serum-based two-miR model, each being able to distinguish patients with good and poor prognosis via Kaplan-Meier analysis with log rank test. Additionally, we integrated miRNA and gene expression data to identify potentially important miRNA-mRNA interactions that are disrupted in canine OS. Integrated analyses of miRNAs in the three-miR predictive model and disrupted genes from previous expression studies suggest the contribution of the primary tumor microenvironment to the metastatic phenotype of aggressive tumors.

TET repression and increased DNMT activity synergistically induce aberrant DNA methylation

Chronic inflammation is deeply involved in various human disorders, such as cancer, neurodegenerative disorders, and metabolic disorders. Induction of epigenetic alterations, especially aberrant DNA methylation, is one of the major mechanisms, but how it is induced is still unclear. Here, we found that expression of TET genes, methylation erasers, was downregulated in inflamed mouse and human tissues, and that this was caused by upregulation of TET-targeting miRNAs such as MIR20A, MIR26B, and MIR29C, likely due to activation of NF-κB signaling downstream of IL-1β and TNF-α. However, TET knockdown induced only mild aberrant methylation. Nitric oxide (NO), produced by NOS2, enhanced enzymatic activity of DNA methyltransferases (DNMTs), methylation writers, and NO exposure induced minimal aberrant methylation. In contrast, a combination of TET knockdown and NO exposure synergistically induced aberrant methylation, involving genomic regions not methylated by either alone. The results showed that a vicious combination of TET repression, due to NF-κB activation, and DNMT activation, due to NO production, is responsible for aberrant methylation induction in human tissues.

DHA Abolishes the Detrimental Effect of Docetaxel on Downregulation of the MICA via Decreasing the Expression Level of MicroRNA-20a in Gastric Cancer

BACKGROUND

MHC class I chain-related protein A (MICA) is a membrane glycoprotein expressed abnormally on some malignant cells including gastric cancer (GC) cell and elicits anti-tumor immune responses. Downregulation of MICA expression could lead to immune-evasion of cancer cells.

OBJECTIVE(S)

In this study, we aimed to investigate the effect of docosahexaenoic acid (DHA) and docetaxel alone or in combination on the expression level of MICA and its regulating microRNA (miRNA), miR-20a in MKN45 GC cell line.

METHOD(S)

MKN45 GC cell line was cultured and MTT assay was performed to determine IC50 of docetaxel. Cells were treated by 18.5 μM docetaxel and 100 μM DHA. After that, RNA extraction and cDNA synthesis were done and the expression level of MICA and miR-20a were determined by quantitative real-time PCR for both treated and untreated cell lines.

RESULTS

Our findings showed less downregulation of the expression level of MICA by the combination of docetaxel/DHA (5.34-fold) compared with docetaxel (45.45-fold) and DHA (55.55-fold). Consistently, combination therapy led to the more downregulation of the expression level of the miR-20a (5.20-fold) in comparison to docetaxel (2.38-fold) and DHA (1.60-fold).

CONCLUSION(S)

As an unwanted effect of docetaxel therapy in GC, downregulation of MICA expression could lead to weak anti-tumor immune responses. By increasing the expression level of MICA, combination therapy of docetaxel with DHA would be useful to overcome this side effect.

The role of microRNAs in cell death pathways

MicroRNAs (miRNAs) are a class of noncoding RNAs that negatively regulate target messenger RNAs. In multicellular eukaryotes, numerous miRNAs perform basic cellular functions, including cell proliferation, differentiation, and death. Abnormal expression of miRNAs weakens or modifies various apoptosis pathways, leading to the development of human cancer. Cell death occurs in an active manner that maintains tissue homeostasis and eliminates potentially harmful cells through regulated cell death processes, including apoptosis, autophagic cell death, and necroptosis. In this review, we discuss the involvement of miRNAs in regulating cell death pathways in cancers and the potential therapeutic functions of miRNAs in cancer treatment.

Role of microRNAs in the crosstalk between osteosarcoma cells and the tumour microenvironment

Osteosarcoma (OS) is the most common primary bone tumour, with a peak incidence in adolescents, and the five-year survival rate of patients with metastasis or recurrence is much lower than that of patients without metastasis and recurrence. OS is initiated and develops in a complex tumour microenvironment (TME) that contains many different components, such as osteoblasts, osteoclasts, mesenchymal stem cells, fibroblasts, immune cells, extracellular matrix (ECM), extracellular vesicles, and cytokines. The extensive interaction between OS and the TME underlies OS progression. Therefore, rather than targeting OS cells, targeting the key factors in the TME may yield novel therapeutic approaches. MicroRNAs (miRNAs) play multiple roles in the biological behaviours of OS, and recent studies have implied that miRNAs are involved in mediating the communication between OS cells and the surrounding TME. Here, we review the TME landscape and the miRNA dysregulation of OS, describe the role of the altered TME in OS development and highlight the role of miRNA in the crosstalk between OS cells and the TME.

Small molecule recognition of disease-relevant RNA structures

Targeting RNAs with small molecules represents a new frontier in drug discovery and development. The rich structural diversity of folded RNAs offers a nearly unlimited reservoir of targets for small molecules to bind, similar to small molecule occupancy of protein binding pockets, thus creating the potential to modulate human biology. Although the bacterial ribosome has historically been the most well exploited RNA target, advances in RNA sequencing technologies and a growing understanding of RNA structure have led to an explosion of interest in the direct targeting of human pathological RNAs. This review highlights recent advances in this area, with a focus on the design of small molecule probes that selectively engage structures within disease-causing RNAs, with micromolar to nanomolar affinity. Additionally, we explore emerging RNA-target strategies, such as bleomycin A5 conjugates and ribonuclease targeting chimeras (RIBOTACs), that allow for the targeted degradation of RNAs with impressive potency and selectivity. The compounds discussed in this review have proven efficacious in human cell lines, patient-derived cells, and pre-clinical animal models, with one compound currently undergoing a Phase II clinical trial and another that recently garnerd FDA-approval, indicating a bright future for targeted small molecule therapeutics that affect RNA function.

Noncoding RNAs: the shot callers in tumor immune escape

Immunotherapy, designed to exploit the functions of the host immune system against tumors, has shown considerable potential against several malignancies. However, the utility of immunotherapy is heavily limited due to the low response rate and various side effects in the clinical setting. Immune escape of tumor cells may be a critical reason for such low response rates. Noncoding RNAs (ncRNAs) have been identified as key regulatory factors in tumors and the immune system. Consequently, ncRNAs show promise as targets to improve the efficacy of immunotherapy in tumors. However, the relationship between ncRNAs and tumor immune escape (TIE) has not yet been comprehensively summarized. In this review, we provide a detailed account of the current knowledge on ncRNAs associated with TIE and their potential roles in tumor growth and survival mechanisms. This review bridges the gap between ncRNAs and TIE and broadens our understanding of their relationship, providing new insights and strategies to improve immunotherapy response rates by specifically targeting the ncRNAs involved in TIE.

MicroRNAs signatures, bioinformatics analysis of miRNAs, miRNA mimics and antagonists, and miRNA therapeutics in osteosarcoma

MicroRNAs (miRNAs) involved in key signaling pathways and aggressive phenotypes of osteosarcoma (OS) was discussed, including PI3K/AKT/MTOR, MTOR AND RAF-1 signaling, tumor suppressor P53- linked miRNAs, NOTCH- related miRNAs, miRNA -15/16 cluster, apoptosis related miRNAs, invasion-metastasis-related miRNAs, and 14Q32-associated miRNAs cluster. Herrin, we discussed insights into the targeted therapies including miRNAs (i.e., tumor-suppressive miRNAs and oncomiRNAs). Using bioinformatics tools, the interaction network of all OS-associated miRNAs and their targets was also depicted.

miR-20a/Foxj2 Axis Mediates Growth and Metastasis of Colorectal Cancer Cells as Identified by Integrated Analysis

BACKGROUND MicroRNAs (miRNAs) have a significant regulatory effect on the proliferation, migration, and invasion of cells, and have been widely reported to have oncogenic or tumor-suppressive impacts on various tumors. In the present study we assessed the regulation and function of miR-20a on colorectal cancer (CRC) cell lines. MATERIAL AND METHODS qPCR was used to quantify miR-20a expression. Luciferase reporter assay was conducted to confirm Foxj2 3'UTR associations. In addition, the function of miR-20a and Foxj2 in CRC was detected using MTT, colony formation, transwell assays, and cell cycle analysis. RESULTS Our data revealed that miR-20a expression was elevated in the CRC cell lines, and cell migration, proliferation, and invasion abilities were promoted by the overexpression of miR-20a. Moreover, Foxj2 was authenticated as a direct target gene of miR-20a in CRC cells. Furthermore, we found that the ectopic Foxj2 dramatically suppressed miR-20a-promoted proliferation, migration, invasion, and xenografts in vitro and in vivo, and induced cell cycle arrest at G1 stage. CONCLUSIONS Our results showing the roles of miR-20a/Foxj2 in carcinogenesis of CRC may help improve treatment of CRC.

Targeted Degradation of the Oncogenic MicroRNA 17-92 Cluster by Structure-Targeting Ligands

Many RNAs are processed into biologically active transcripts, the aberrant expression of which can contribute to disease phenotypes. For example, the primary microRNA-17-92 (pri-miR-17-92) cluster contains six microRNAs (miRNAs) that collectively act in several disease settings. Herein, we used sequence-based design of structure-specific ligands to target a common structure in the Dicer processing sites of three miRNAs in the cluster, miR-17, miR-18a, and miR-20a, thereby inhibiting their biogenesis. The compound was optimized to afford a dimeric molecule that binds the Dicer processing site and an adjacent bulge, affording a 100-fold increase in potency. The dimer's mode of action was then extended from simple binding to direct cleavage by conjugation to bleomycin A5 in a manner that imparts RNA-selective cleavage or to indirect cleavage by recruiting an endogenous nuclease, or a ribonuclease targeting chimera (RIBOTAC). Interestingly, the dimer-bleomycin conjugate cleaves the entire pri-miR-17-92 cluster and hence functionally inhibits all six miRNAs emanating from it. The compound selectively reduced levels of the cluster in three disease models: polycystic kidney disease, prostate cancer, and breast cancer, rescuing disease-associated phenotypes in the latter two. Further, the bleomycin conjugate exerted selective effects on the miRNome and proteome in prostate cancer cells. In contrast, the RIBOTAC only depleted levels of pre- and mature miR-17, -18a, and 20a, with no effect on the primary transcript, in accordance with the cocellular localization of RNase L, the pre-miRNA targets, and the compound. These studies demonstrate a strategy to tune RNA structure-targeting compounds to the cellular localization of the target.

Radiosensitization of Hepatocellular Carcinoma through Targeting Radio-Associated MicroRNA

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related deaths worldwide. For patients who are resistant to monotherapy, multimodal therapy is a basic oncologic principle that incorporates surgery, radiotherapy (RT), and chemotherapy providing survival benefits for patients with most types of cancer. Although liver has low tolerance for radiation, high-precision RT for local HCC minimizes the likelihood of radiation-induced liver disease (RILD) in noncancerous liver tissue. RT have several therapeutic benefits, including the down-staging of tumors to make them resectable and repression of metastasis. The DNA damage response (DDR) is a cellular response to irradiation (IR), including DNA repair of injured cells and induction of programmed cell death, thereby resulting in maintenance of cell homeostasis. Molecules that block the activity of proteins in DDR pathways have been found to enhance radiotherapeutic effects. These molecules include antibodies, kinase inhibitors, siRNAs and miRNAs. MicroRNAs (miRNAs) are short non-coding regulatory RNAs binding to the 3'-untranslated regions (3'-UTR) of the messenger RNAs (mRNAs) of target genes, regulating their translation and expression of proteins. Thus, miRNAs and their target genes constitute complicated interactive networks, which interact with other molecules during carcinogenesis. Due to their promising roles in carcinogenesis, miRNAs were shown to be the potential factors that mediated radiosensitivity and optimized outcomes of the combination of systemic therapy and radiotherapy.

The Fas/FasL Signaling Pathway: Its Role in the Metastatic Process and as a Target for Treating Osteosarcoma Lung Metastases

Understanding how the tumor microenvironment participates in inhibiting or supporting tumor growth is critical for the development of novel therapies. Osteosarcoma (OS) metastasizes almost exclusively to the lung, an organ where Fas ligand (FasL) is constitutively expressed. This chapter focuses on our studies dedicated to the interaction of OS cells with the lung microenvironment. We will summarize our studies conducted over the past 20 years showing the importance of the Fas/FasL signaling pathway to the establishment and progression of OS metastases in the lung. We demonstrated that the FasL⁺ lung microenvironment eliminates Fas-positive (Fas⁺) OS cells that metastasize to the lungs, through apoptosis induced by Fas signaling following interaction of Fas on the tumor cell surface with FasL on the lung epithelial cells. Expression of the Fas receptor on OS cells inversely correlated with the ability of OS cells to form lung metastases. Blocking this pathway interferes with this process, allowing Fas⁺ cells to grow in the lung. By contrast, upregulation of Fas on Fas^- OS cells inhibited their ability to metastasize to the lung. We demonstrated how the FasL⁺ lung microenvironment can be leveraged for therapeutic intent through the upregulation of Fas expression. To this end, we demonstrated that the histone deacetylase inhibitor entinostat upregulated Fas expression on OS cells, reduced their ability to form lung metastases, and induced regression of established micrometastases. Fas expression in OS cells is regulated epigenetically by the microRNA miR-20a. We showed that expressions of Fas and miR-20a are inversely correlated, and that delivery of anti-miR-20a in vivo to mice with established osteosarcoma lung metastases resulted in upregulation of Fas and tumor regression. Therefore, targeting the Fas signaling pathway may present therapeutic opportunities, which target the lung microenvironment for elimination of OS lung metastases. We have also shown that in addition to being critically involved in the metastatic potential, the Fas signaling pathway may also contribute to the efficacy of chemotherapy. We demonstrated that the chemotherapeutic agent gemcitabine (GCB) increased Fas expression in both human and mouse OS cells in vitro. In vivo, aerosol GCB therapy induced upregulation of Fas expression and the regression of established osteosarcoma lung metastases. The therapeutic efficacy of GCB was contingent upon a FasL⁺ lung microenvironment as aerosol GCB had no effect in FasL-deficient mice. Manipulation of Fas expression and the Fas pathway should be considered, as this concept may provide additional novel therapeutic approaches for treating patients with OS lung metastases.

LncRNA HIF1A-AS2 promotes osteosarcoma progression by acting as a sponge of miR-129-5p

Increasing studies have demonstrated that long noncoding RNAs (lncRNAs) play vital roles in tumor development and progression. However, the relationship between osteosarcoma and HIF1AAS2 remains unknown. The expression of HIF1AAS2 and miR-129-5p was detected in osteosarcoma cell lines and samples via qRT-PCR. Cell Counting Kit-8 (CCK-8) and invasion assays were performed to determine cell proliferation and invasion ability, and a dual luciferase reporter assay was performed to determine the interaction between HIF1AAS2 and miR-129-5p. We showed that the expression of HIF1A-AS2 was upregulated in the osteosarcoma samples compared with the expression in noncancerous samples. Moreover, patients with high HIF1A-AS2 expression had a shorter overall survival. Ectopic expression of HIF1A-AS2 enhanced osteosarcoma cell proliferation, cell cycle progression and invasion. We found that overexpression of miR-129-5p decreased the luciferase activity of wild-type (WT) HIF1A-AS2 but not mutant HIF1A-AS2. Ectopic expression of HIF1A-AS2 suppressed miR-129-5p expression in MG-63 cells. We demonstrated that miR-129-5p was downregulated in osteosarcoma and was negatively associated with HIF1A-AS2 expression. Furthermore, ectopic expression of miR-129-5p suppressed osteosarcoma cell proliferation, cell cycle progression and invasion. In addition, overexpression of HIF1A-AS2 promoted cell proliferation, cell cycle progression and invasion of osteosarcoma cells through the modulation of miR-129-5p. These results indicated that HIF1A-AS2 might be a potential therapeutic target for osteosarcoma.

Biology and pathogenesis of human osteosarcoma

Osteosarcoma (OS) is a bone tumor of mesenchymal origin, most frequently occurring during the rapid growth phase of long bones, and usually located in the epiphyseal growth plates of the femur or the tibia. Its most common feature is genome disorganization, aneuploidy with chromosomal alterations, deregulation of tumor suppressor genes and of the cell cycle, and an absence of DNA repair. This suggests the involvement of surveillance failures, DNA repair or apoptosis control during osteogenesis, allowing the survival of cells which have undergone alterations during differentiation. Epigenetic events, including DNA methylation, histone modifications, nucleosome remodeling and expression of non-coding RNAs have been identified as possible risk factors for the tumor. It has been reported that p53 target genes or those genes that have their activity modulated by p53, in addition to other tumor suppressor genes, are silenced in OS-derived cell lines by hypermethylation of their promoters. In osteogenesis, osteoblasts are formed from pluripotent mesenchymal cells, with potential for self-renewal, proliferation and differentiation into various cell types. This involves complex signaling pathways and multiple factors. Any disturbance in this process can cause deregulation of the differentiation and proliferation of these cells, leading to the malignant phenotype. Therefore, the origin of OS seems to be multifactorial, involving the deregulation of differentiation of mesenchymal cells and tumor suppressor genes, activation of oncogenes, epigenetic events and the production of cytokines.

MiR-421 promotes the development of osteosarcoma by regulating MCPIP1 expression

Despite improvements in surgical resection and adjuvant chemotherapy, the prognosis and outcomes of patients with osteosarcoma remains poor due to the occurrence of metastasis or relapse. Monocyte chemoattractant protein-1-induced protein-1 (MCPIP1), a zinc-finger RNA-binding protein, is known to regulate inflammatory responses and repress breast cancer growth. However, the regulation of MCPIP1 by microRNAs has not been clearly elucidated in osteosarcoma. In this study, we found that miR-421 expression was upregulated and MCPIP1 expression was downregulated in the osteosarcoma specimens from patients. Moreover, MCPIP1 expression was inversely correlated with miR-421 expression in the clinical samples. Furthermore, the upregulation of miR-421 and downregulation of MCPIP1 resulted in poor overall survival and severe disease progression, respectively, in the patients with osteosarcoma. Bioinformatics analysis and luciferase reporter gene assays confirmed that miR-421 specifically targets and binds to the 3'-UTR of MCPIP1. The overexpression of miR-421 induced cell proliferation, invasion, and migration, and the release of pro-inflammatory IL-6 in cultured human osteosarcoma cells. Additionally, the administration of miR-421 to tumor-bearing mice facilitated osteosarcoma growth by downregulating MCPIP1 expression. Taken together, these findings indicate that miR-421 is able to promote the development of osteosarcoma by regulating MCPIP1 expression, and can be a potential therapeutic target for osteosarcoma.

Non-Coding RNAs in Pediatric Solid Tumors

Pediatric solid tumors are a diverse group of extracranial solid tumors representing approximately 40% of childhood cancers. Pediatric solid tumors are believed to arise as a result of disruptions in the developmental process of precursor cells which lead them to accumulate cancerous phenotypes. In contrast to many adult tumors, pediatric tumors typically feature a low number of genetic mutations in protein-coding genes which could explain the emergence of these phenotypes. It is likely that oncogenesis occurs after a failure at many different levels of regulation. Non-coding RNAs (ncRNAs) comprise a group of functional RNA molecules that lack protein coding potential but are essential in the regulation and maintenance of many epigenetic and post-translational mechanisms. Indeed, research has accumulated a large body of evidence implicating many ncRNAs in the regulation of well-established oncogenic networks. In this review we cover a range of extracranial solid tumors which represent some of the rarer and enigmatic childhood cancers known. We focus on two major classes of ncRNAs, microRNAs and long non-coding RNAs, which are likely to play a key role in the development of these cancers and emphasize their functional contributions and molecular interactions during tumor formation.

Reciprocal regulatory mechanism between miR-214-3p and FGFR1 in FGFR1-amplified lung cancer

MicroRNA (miRNA) and fibroblast growth factor receptor 1 (FGFR1) dysregulation are considered to play an important role in tumor proliferation, invasion, and metastasis. However, the regulatory mechanism between miRNAs and FGFR1 in lung cancer remains unclear and extremely critical. miR-214-3p was sharply decreased and showed a significantly negative correlation with FGFR1 in lung cancer patients (n = 30). Luciferase reporter assay confirmed that miR-214-3p could downregulate FGFR1 by directly targeting 3′-untranslated region (UTR). miR-214-3p inhibited the processes of epithelial–mesenchymal transition and Wnt/MAPK/AKT (Wnt/mitogen-activated protein kinase/AKT) signaling pathway by targeting FGFR1. Moreover, miR-214-3p not only established a negative feedback regulation loop with FGFR1 through ERK (extracellular signal-regulated kinase) but also developed a synergism with FGFR1 inhibitor AZD4547. In conclusion, our study demonstrated the regulatory mechanism between miR-214-3p and FGFR1 in lung cancer. miR-214-3p acts as a vital target in FGFR1-amplified lung cancer by forming a miR-214-3p-FGFR1-Wnt/MAPK/AKT signaling pathway network. Co-targeting miR-214-3p and FGFR1 could provide greater benefits to patients with FGFR1-amplified lung cancer.

A Cell's Fate: An Overview of the Molecular Biology and Genetics of Apoptosis

Apoptosis is one of the main types of regulated cell death, a complex process that can be triggered by external or internal stimuli, which activate the extrinsic or the intrinsic pathway, respectively. Among various factors involved in apoptosis, several genes and their interactive networks are crucial regulators of the outcomes of each apoptotic phase. Furthermore, mitochondria are key players in determining the way by which cells will react to internal stress stimuli, thus being the main contributor of the intrinsic pathway, in addition to providing energy for the whole process. Other factors that have been reported as important players of this intricate molecular network are miRNAs, which regulate the genes involved in the apoptotic process. Imbalance in any of these mechanisms can lead to the development of several illnesses, hence, an overall understanding of these processes is essential for the comprehension of such situations. Although apoptosis has been widely studied, the current literature lacks an updated and more general overview on this subject. Therefore, here, we review and discuss the mechanisms of apoptosis, highlighting the roles of genes, miRNAs, and mitochondria involved in this type of cell death.

MicroRNAs in cancer cell death pathways: Apoptosis and necroptosis

To protect tissues and the organism from disease, potentially harmful cells are removed through programmed cell death processes, including apoptosis and necroptosis. These types of cell death are critically controlled by microRNAs (miRNAs). MiRNAs are short RNA molecules that target and inhibit expression of many cellular regulators, including those controlling programmed cell death via the intrinsic (Bcl-2 and Mcl-1), extrinsic (TRAIL and Fas), p53-and endoplasmic reticulum (ER) stress-induced apoptotic pathways, as well as the necroptosis cell death pathway. In this review, we discuss the current knowledge of apoptosis and necroptosis pathways and how these are impaired in cancer cells. We focus on how miRNAs disrupt apoptosis and necroptosis, thereby critically contributing to malignancy. Understanding which and how miRNAs and their targets affect cell death pathways could open up novel therapeutic opportunities for cancer patients. Indeed, restoration of pro-apoptotic tumor suppressor miRNAs (apoptomiRs) or inhibition of oncogenic miRNAs (oncomiRs) represent strategies that are currently being trialed or are already applied as miRNA-based cancer therapies. Therefore, better understanding the cancer type-specific expression of apoptomiRs and oncomiRs and their underlying mechanisms in cell death pathways will not only advance our knowledge, but also continue to provide new opportunities to treat cancer.

Assessment of Apoptosis Pathway in Peripheral Blood of Autistic Patients

Autism spectrum disorder (ASD) includes a number of severe neurodevelopmental disorders known by defects in social interaction, impaired verbal and non-verbal interactions, and stereotypic activities and limited interests. Dysregulation of apoptotic pathways have been demonstrated in brain tissues of affected individuals. In the present study, we evaluated expression levels of apoptosis-related genes and miRNAs in peripheral blood of ASD patients compared with healthy subjects. Transcript levels of BCL2, CASP8, and hsa-29c-3p were significantly lower in total ASD patients compared with total normal children (P values = 0.003, 0.002, and 0.01 respectively). When sex of study participants was considered in the analysis, the difference in transcript levels of these genes was significant only in male subjects. Peripheral expression of BCL2 and hsa-29c-3p had 100% sensitivity 92% specificity in ASD diagnosis. The diagnostic power of combination of transcript levels of these genes was estimated to be 78% based on the calculated AUC value. The present study provides evidences for dysregulation of apoptotic pathways in peripheral blood of ASD patients and suggests certain apoptosis-related genes as biomarkers in this regard.

Knockdown of lncRNA XIST suppresses osteosarcoma progression by inactivating AKT/mTOR signaling pathway by sponging miR-375-3p

BACKGROUND

Osteosarcoma (OS) is one of the most common bone tumors in adolescents and young adults. Emerging evidence suggested ncRNA (lncRNA and miRNA) are closely associated with cell progression, apoptosis and autophagy. However, the role of regulatory network between ncRNA and mRNA in OS has not been fully verified.

METHODS

lncRNA XIST, miRNA expression were detected by qRT-PCR. The protein expression of LC3, p62, AKT, p-AKT, mTOR and p-mTOR was measured by western blot. MTT assay and flow cytometry were applied to measure cell proliferation and apoptosis. Luciferase assay was used to ensure the relationship between lncRNA, miRNA and mRNA. GFP-LC3 cells were observed using fluorescence microscope.

RESULTS

XIST expression was up-regulated but miR-375-3p was down-regulated in OS tissues and cells. Luciferase assay results demonstrated that miR-375-3p was a target of XIST and mTOR was a target mRNA of miR-375-3p. In addition, knockdown of XIST and mTOR inhibited OS cell proliferation and autophagy, but induced apoptosis. Knockdown of XIST could reverse the effect of miR-375-3p inhibitor on OS cells. The effects of si-mTOR of OS cells could be reversed by silencing miR-375-3p. Moreover, knockdown of XIST inhibited AKT/mTOR signaling pathway via sponging miR-375-3p.

CONCLUSION

Knockdown of XIST inhibited cell growth and autophagy but induced cell apoptosis by suppressing the AKT/mTOR signaling pathway by sponging miR-375-3p.

From genomics to metabolomics: emerging metastatic biomarkers in osteosarcoma

Although the investigation into biomarkers specific for pulmonary metastasis within osteosarcoma (OS) has recently expanded, their usage within the clinic remains sparse. The current screening protocol after any OS diagnosis includes a chest CT scan; however, metastatic lung nodules frequently go undetected and remain the primary cause of death in OS. Recently, screening technologies such as liquid biopsy and next-generation sequencing have revealed a promising array of biomarkers with predictive and diagnostic value for the pulmonary metastasis associated with OS. These biomarkers draw from genomics, transcriptomics, epigenetics, and metabolomics. When assessed in concert, their utility is most promising as OS is a highly heterogeneous cancer. Accordingly, there has been an expansion of clinical trials not only aimed at further demonstrating the significance of these individual biomarkers but to also reveal which therapies resolve the pulmonary metastasis once detected. This review will focus on the recently discovered and novel metastatic biomarkers within OS, their molecular and cellular mechanisms, the expansion of humanized OS mouse models amenable to their testing, and the associated clinical trials aimed at managing the metastatic phase of OS.

Role of microRNA-92a in metastasis of osteosarcoma cells in vivo and in vitro by inhibiting expression of TCF21 with the transmission of bone marrow derived mesenchymal stem cells

Background

This study aims to investigate the role of microRNA-92a (miR-92a) in metastasis of osteosarcoma (OS) cells in vivo and in vitro by regulatingTCF21 with the transmission of bone marrow derived mesenchymal stem cells (BMSCs).

Methods

BMSCs were isolated, purified and cultured from healthy adult bone marrow tissues. The successfully identified BMSCs were co-cultured with OS cells, and the effects of BMSCs on the growth metastasis of OS cells in vitro and in vivo were determined. qRT-PCR and western blot analysis was used to detect the expression of miR-92a and TCF21 in OS cells and OS cells co-cultured with BMSCs. Proliferation, invasion and migration of OS cells transfected with miR-92a mimics and miR-92a inhibitors was determined, and the tumorigenesis and metastasis of OS cells in nude mice were observed. Expression of miR-92a and TCF21 mRNA in tissue specimens as well as the relationship between the expression of miR-92a and the clinicopathological features of OS was analyzed.

Results

BMSCs promoted proliferation, invasion and migration of OS cells in vitro together with promoted the growth and metastasis of OS cells in vivo. Besides, high expression of miR-92a was found in OS cells co-cultured with BMSCs. Meanwhile, overexpression of miR-92a promoted proliferation, invasion and migration of OS cells in vitro as well as promoted growth and metastasis of OS cells in vivo. The expression of miR-92a increased significantly, and the expression of TCF21 mRNA and protein decreased significantly in OS tissues. Expression of miR-92a was related to Ennecking staging and distant metastasis in OS patients.

Conclusion

Collectively, this study demonstrates that the expression of miR-92a is high in OS and BMSCs transfers miR-92a to inhibit TCF21 and promotes growth and metastasis of OS in vitro and in vivo.

MiRNAs and inflammatory bowel disease: An interesting new story

Inflammatory bowel disease (IBD), as a chronic and recurrent inflammatory disorder, is caused by a dysregulated and aberrant immune response to exposed environmental factors in genetically susceptible individuals. Despite huge efforts in determining the molecular pathogenesis of IBD, an increasing worldwide incidence of IBD has been reported. MicroRNAs (miRNAs) are a set of noncoding RNA molecules that are about 22 nucleotides long, and these molecules are involved in the regulation of the gene expression. By clarifying the important role of miRNAs in a number of diseases, their role was also considered in IBD; numerous studies have been performed on this topic. In this review, we attempt to summarize a number of studies and discuss some of the recent developments in the roles of miRNAs in the pathophysiology, diagnosis, and treatment of IBD.

miR-20a inhibits the killing effect of natural killer cells to cervical cancer cells by downregulating RUNX1

BACKGROUND

NK cells are presented in tumor microenvironments and acts as an essential defense line against multiple malignancies. Recently, miRNAs are reported to involve in the development of natural killer (NK) cells via negatively regulating gene expression. Here, we aim to explore the function and mechanism underlying how miR-20a modulated the killing effect of NK cells to cervical cancer cells.

METHODS

Abundances of miR-20a and runt-related transcription factor 1 (RUNX1) in NK cells from cervical cancer patients and healthy donors were detected by qRT-PCR and western blot. The releases of IFN-γ and TNF-α were determined by ELISA. The cytotoxicity of NK cells against cervical cancer cells was measured by CytoTox 96 non-radioactive cytotoxicity assay. Luciferase reporter, western blot, and RNA immunoprecipitation (RIP) assays were performed to assess the interaction between miR-20a and RUNX1.

RESULT

miR-20a was upregulated while RUNX1 was downregulated in NK cells from cervical cancer patients compared to healthy donors. IL-2 stimulated the releases of IFN-γ and TNF-α, and the killing effect of NK cells to cervical cancer cells, which was overturned by miR-20a introduction. RUNX1 was identified to be a target of miR-20a. Restoration of RUNX1 abolished the inhibitory effects of miR-20a on the secretions of IFN-γ and TNF-α, as well as the killing effect of NK cells to colorectal cancer cells.

CONCLUSION

miR-20a attenuated the killing effect of NK cells to cervical cancer cells by directly targeting RUNX1.

Clinical significance of circulating miR-25-3p as a novel diagnostic and prognostic biomarker in osteosarcoma

Background

Emerging evidence has suggested that circulating microRNAs (miRNAs) in body fluids have novel diagnostic and prognostic significance for patients with malignant diseases. The lack of useful biomarkers is a crucial problem of bone and soft tissue sarcomas; therefore, we investigated the circulating miRNA signature and its clinical relevance in osteosarcoma.

Methods

Global miRNA profiling was performed using patient serum collected from a discovery cohort of osteosarcoma patients and controls and cell culture media. The secretion of the detected miRNAs from osteosarcoma cells and clinical relevance of serum miRNA levels were evaluated using in vitro and in vivo models and a validation patient cohort.

Results

Discovery screening identified 236 serum miRNAs that were highly expressed in osteosarcoma patients compared with controls, and eight among these were also identified in the cell culture media. Upregulated expression levels of miR-17-5p and miR-25-3p were identified in osteosarcoma cells, and these were abundantly secreted into the culture media in tumor-derived exosomes. Serum miR-25-3p levels were significantly higher in osteosarcoma patients than in control individuals in the validation cohort, with favorable sensitivity and specificity compared with serum alkaline phosphatase. Furthermore, serum miR-25-3p levels at diagnosis were correlated with patient prognosis and reflected tumor burden in both in vivo models and patients; these associations were more sensitive than those of serum alkaline phosphatase.

Conclusions

Serum-based circulating miR-25-3p may serve as a non-invasive blood-based biomarker for tumor monitoring and prognostic prediction in osteosarcoma patients.

MicroRNAs for osteosarcoma in the mouse: a meta-analysis

Osteosarcoma (OS) is the most common primary malignant bone carcinoma with high morbidity that happens mainly in children and young adults. As the key components of gene-regulatory networks, microRNAs (miRNAs) control many critical pathophysiological processes, including initiation and progression of cancers. The objective of this study is to summarize and evaluate the potential of miRNAs as targets for prevention and treatment of OS in mouse models, and to explore the methodological quality of current studies. We searched PubMed, Web of Science, Embase, Wan Fang Database, VIP Database, China Knowledge Resource Integrated Database, and Chinese BioMedical since their beginning date to 10 May 2016. Two reviewers separately screened the controlled studies, which estimate the effects of miRNAs on osteosarcoma in mice. A pair-wise analysis was performed. Thirty six studies with enough randomization were selected and included in the meta-analysis. We found that blocking oncogenic or restoring decreased miRNAs in cancer cells could significantly suppress the progression of OS in vivo, as assessed by tumor volume and tumor weight. This meta-analysis suggests that miRNAs are potential therapeutic targets for OS and correction of the altered expression of miRNAs significantly suppresses the progression of OS in mouse models, however, the overall methodological quality of studies included here was low, and more animal studies with the rigourous design must be carried out before a miRNA-based treatment could be translated from animal studies to clinical trials.

Alteration in microRNA-17-92 dynamics accounts for differential nature of cellular proliferation

MicroRNAs associated with the mir-17-92 cluster are crucial regulators of the mammalian cell cycle, as they inhibit transcription factors related to the E2F family that tightly control decision-making events for a cell to commit for active cellular proliferation. Intriguingly, in many solid cancers, these mir-17-92 cluster members are overexpressed, whereas in some hematopoietic cancers they are down-regulated. Our proposed model of the Myc/E2F/mir-17-92 network demonstrates that the differential expression pattern of mir-17-92 in different cell types can be conceived due to having a contrasting E2F dynamics induced by mir-17-92. The model predicts that by explicitly altering the mir-17-92-related part of the network, experimentally it is possible to control cellular proliferation in a cell type-dependent manner for therapeutic intervention.

MicroRNA-505 is downregulated in human osteosarcoma and regulates cell proliferation, migration and invasion

Recent studies have demonstrated that microRNAs (miRNAs/miRs) are involved in osteosarcoma tumorigenesis, progression, invasion and metastasis. For example, miR-505 plays important roles in human carcinogenesis; however, its exact function in osteosarcoma remains unclear. MicroRNA profiles of osteosarcoma and normal tissues were obtained by miRNA microarray assays, which were validated by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). Then, high-mobility group box 1 (HMGB1) expression was evaluated by qRT-PCR and western blot analysis. The correlation between miR-505 and HMGB1 was analyzed by Pearson correlation. In vitro, the biological functions of miR-505 were examined by wound healing, MTT and Transwell assays and western blot analysis in MG63 cells transfected with miRNA mimics or empty vector. Luciferase assay was utilized to assess whether HMGB1 is a target of miR-505. miRNA microarrays revealed 26 aberrant miRNAs in osteosarcoma tissues; miR-505 showed the most pronounced decrease (P<0.01), which was significantly associated with TNM stage and metastasis status (P<0.05). In addition, HMGB1 was highly expressed in osteosarcoma tissues (P<0.01), with a significantly negative correlation with miR-505 (r=−0.6679, P<0.001). Furthermore, miR-505 inhibited proliferation, migration and invasion abilities of MG63 cells (P<0.01). Moreover, luciferase activity of the HMGB1-3′-UTR plasmid was suppressed following miR-505 binding (P<0.01). Finally, HMGB1 overexpression partly reversed the effects of miR-505 on MG63 cells. In conclusion, miR-505 levels are decreased in osteosarcoma tissues, and reduced miR-505 expression is significantly associated with poorer clinical prognosis in patients with osteosarcomas. miR-505 inhibits osteosarcoma cell proliferation, migration and invasion by regulating HMGB1.

A miR-20a/MAPK1/c-Myc regulatory feedback loop regulates breast carcinogenesis and chemoresistance

Chemoresistance often leads to the failure of breast cancer treatment. MicroRNAs (miRNAs) play an important role in the progression and chemoresistance of cancer. However, because of the complexity of the mechanisms of chemoresistance and the specificity of miRNA regulation in different cell types, the function of miR-20a in breast cancer chemoresistance is still unclear. Here, by using miRNA microarray and high-content screening techniques, we found that miR-20a/b were significantly downregulated in breast cancer tissues compared with normal breast tissues, and low miR-20a/b expression was correlated with poor survival in breast cancer patients. Ectopic overexpression of miR-20a sensitized breast cancer cells to a broad spectrum of chemotherapy drugs and suppress their proliferation both in vitro and in vivo. Further study demonstrated that miR-20a directly targeted the 3'untranslated region of MAPK1, and thus downregulated the expression of P-gp and c-Myc by inhibiting the MAPK/ERK signaling pathway, whereas c-Myc can bind to the promoter region of the miR-20a gene to promote the expression of miR-20a. Together, our study identified a novel miR-20a/MAPK1/c-Myc feedback loop that regulates breast cancer growth and chemoresistance. These findings suggest that miR-20a synergizing with anticancer drugs will be a promising treatment strategy, especially for chemoresistant patients.

Apoptosis as anticancer mechanism: function and dysfunction of its modulators and targeted therapeutic strategies

Apoptosis is a form of programmed cell death that results in the orderly and efficient removal of damaged cells, such as those resulting from DNA damage or during development. Apoptosis can be triggered by signals from within the cell, such as genotoxic stress, or by extrinsic signals, such as the binding of ligands to cell surface death receptors. Deregulation in apoptotic cell death machinery is an hallmark of cancer. Apoptosis alteration is responsible not only for tumor development and progression but also for tumor resistance to therapies. Most anticancer drugs currently used in clinical oncology exploit the intact apoptotic signaling pathways to trigger cancer cell death. Thus, defects in the death pathways may result in drug resistance so limiting the efficacy of therapies. Therefore, a better understanding of the apoptotic cell death signaling pathways may improve the efficacy of cancer therapy and bypass resistance. This review will highlight the role of the fundamental regulators of apoptosis and how their deregulation, including activation of anti-apoptotic factors (i.e., Bcl-2, Bcl-xL, etc) or inactivation of pro-apoptotic factors (i.e., p53 pathway) ends up in cancer cell resistance to therapies. In addition, therapeutic strategies aimed at modulating apoptotic activity are briefly discussed.

miR-20a Regulates FAS Expression in Osteosarcoma Cells by Modulating FAS Promoter Activity and Can be Therapeutically Targeted to Inhibit Lung Metastases

The metastatic potential of osteosarcoma cells is inversely correlated to cell surface FAS expression. Downregulation of FAS allows osteosarcoma cells to escape FAS ligand-mediated apoptosis when they enter a FAS ligand-positive microenvironment such as the lung. We have previously demonstrated that miR-20a, encoded by the miR-17-92 cluster, downregulates FAS expression in osteosarcoma. We further demonstrated an inverse correlation between FAS expression and miR-20a expression. However, the mechanism of FAS regulation by miR-20a was still unclear. The purpose of the current study was to evaluate the mechanism of FAS regulation by miR-20a in vitro and test the effect of targeting miR-20a in vivo We investigated whether miR-20a's downregulation of FAS was mediated by binding to the 3'-untranslated region (3'-UTR) of FAS mRNA with the consequent induction of mRNA degradation or translational suppression. We identified and mutated two miR-20a binding sites on the FAS mRNA 3'-UTR. Using luciferase reporter assays, we demonstrated that miR-20a did not bind to either the wild-type or mutated FAS 3'-UTR. In contrast, overexpression of miR-20a resulted in downregulation of FAS promoter activity. Similarly, the inhibition of miR-20a increased FAS promoter activity. The critical region identified on the FAS promoter was between -240 bp and -150 bp. Delivery of anti-miR-20a in vivo using nanoparticles in mice with established osteosarcoma lung metastases resulted in upregulation of FAS and tumor growth inhibition. Taken together, our data suggest that miR-20a regulates FAS expression through the modulation of the FAS promoter and that targeting miR-20a using anti-miR-20a has therapeutic potential. Mol Cancer Ther; 17(1); 130-9. ©2017 AACR.

MiR-302b Suppresses Osteosarcoma Cell Migration and Invasion by Targeting Runx2

Osteosarcoma patients with lung metastasis and local invasion remain challenging to treat despite the significant contribution of the combination of surgery and neo-adjuvant chemotherapy. Our previous microarray study demonstrated that miR-302b had significantly lower expression in osteosarcoma cell lines than in osteoblast cell lines. In the present study, we further elucidated the role of miR-302b in regulating the migration and invasiveness of osteosarcoma. MiR-302b expression was markedly down-regulated in osteosarcoma cell lines and clinical tumour tissues. Lower levels of miR-302b expression were significantly associated with metastasis and high pathological grades. A functional study demonstrated that over-expression of miR-302b suppressed tumour cell proliferation, invasion and migration in vitro and in vivo. Runx2 was identified as a direct target gene for miR-302b by bioinformatics analysis and dual-luciferase reporter gene assay. Moreover, over-expression of miR-302b induced down-regulation of Runx2, OPN, MMP-2, MMP-9, MMP-12, MMP-14, and VEGF in 143B cells. Exogenous expression of Runx2 partially rescued the inhibitory effect of miR-302b on the invasion and migration activity of 143B osteosarcoma cells. Taken together, our results indicate that miR-302b functions as a tumour repressor in the invasion and migration of osteosarcoma by directly downregulating Runx2 expression and may be a potential therapeutic target for osteosarcoma.