Non-Coding RNAs: Functional Aspects and Diagnostic Utility in Oncology

Non-coding RNA: A key regulator in the Glutathione-GPX4 pathway of ferroptosis

Ferroptosis, a form of regulated cell death, has emerged as a crucial process in diverse pathophysiological states, encompassing cancer, neurodegenerative ailments, and ischemia-reperfusion injury. The glutathione (GSH)-dependent lipid peroxidation pathway, chiefly governed by glutathione peroxidase 4 (GPX4), assumes an essential part in driving ferroptosis. GPX4, as the principal orchestrator of ferroptosis, has garnered significant attention across cancer, cardiovascular, and neuroscience domains over the past decade. Noteworthy investigations have elucidated the indispensable functions of ferroptosis in numerous diseases, including tumorigenesis, wherein robust ferroptosis within cells can impede tumor advancement. Recent research has underscored the complex regulatory role of non-coding RNAs (ncRNAs) in regulating the GSH-GPX4 network, thus influencing cellular susceptibility to ferroptosis. This exhaustive review endeavors to probe into the multifaceted processes by which ncRNAs control the GSH-GPX4 network in ferroptosis. Specifically, we delve into the functions of miRNAs, lncRNAs, and circRNAs in regulating GPX4 expression and impacting cellular susceptibility to ferroptosis. Moreover, we discuss the clinical implications of dysregulated interactions between ncRNAs and GPX4 in several conditions, underscoring their capacity as viable targets for therapeutic intervention. Additionally, the review explores emerging strategies aimed at targeting ncRNAs to modulate the GSH-GPX4 pathway and manipulate ferroptosis for therapeutic advantage. A comprehensive understanding of these intricate regulatory networks furnishes insights into innovative therapeutic avenues for diseases associated with perturbed ferroptosis, thereby laying the groundwork for therapeutic interventions targeting ncRNAs in ferroptosis-related pathological conditions.

Critical role of non-coding RNA-mediated ferroptosis in urologic malignancies

Urologic malignancies, characterized by their high aggressiveness and metastatic potential, pose a significant public health challenge globally. Ferroptosis, a novel mode of cell death, typically arises from intracellular iron ion overload and the accumulation of lipid peroxides. This process has been shown to play a crucial regulatory role in various pathological conditions, particularly in cancer, including urologic cancers. However, the comprehensive regulatory mechanisms underlying ferroptosis remain poorly understood, which somewhat limits its broader application in cancer therapy. Non-coding RNAs (ncRNAs), which encompass microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are non-coding transcripts that play pivotal roles in various physiological processes, such as proliferation, differentiation, apoptosis, and cell cycle regulation, by modulating the expression of target genes. The biological functions and potential regulatory mechanisms of ncRNAs in the context of cancer-related ferroptosis have been partially elucidated. Research indicates that ncRNAs can influence the progression of urologic cancers by affecting cell proliferation, migration, and drug resistance through the regulation of ferroptosis. Consequently, this review aims to clarify the functions and mechanisms of the ncRNA-ferroptosis axis in urologic cancers and to evaluate the clinical significance of ferroptosis-related ncRNAs, thereby providing new insights into cancer biology and therapeutic strategies that may ultimately benefit a diverse range of cancer patients.

CircRNA and lncRNA-associated competing endogenous RNA networks in medulloblastoma: a scoping review

BACKGROUND

Medulloblastoma is one of the common primary central nervous system (CNS) malignancies in pediatric patients. The main treatment is surgical resection preceded and/or followed by chemoradiotherapy. However, their serious side effects necessitate a better understanding of medulloblastoma biology to develop novel therapeutic options.

MAIN BODY

Circular RNA (circRNA) and long non-coding RNA (lncRNA) regulate gene expression via microRNA (miRNA) pathways. Although growing evidence has highlighted the significance of circRNA and lncRNA-associated competing endogenous RNA (ceRNA) networks in cancers, no study has comprehensively investigated them in medulloblastoma. For this aim, the Web of Science, PubMed, Scopus, and Embase were systematically searched to obtain the relevant papers published before 16 September 2023, adhering to the PRISMA-ScR statement. HOTAIR, NEAT1, linc-NeD125, HHIP-AS1, CRNDE, and TP73-AS1 are the oncogenic lncRNAs, and Nkx2-2as is a tumor-suppressive lncRNA that develop lncRNA-associated ceRNA networks in medulloblastoma. CircSKA3 and circRNA_103128 are upregulated oncogenic circRNAs that develop circRNA-associated ceRNA networks in medulloblastoma.

CONCLUSION

In summary, this study has provided an overview of the existing evidence on circRNA and lncRNA-associated ceRNA networks and their impact on miRNA and mRNA expression involved in various signaling pathways of medulloblastoma. Suppressing the oncogenic ceRNA networks and augmenting tumor-suppressive ceRNA networks can provide ample opportunities for medulloblastoma treatment.

Insights into the Roles of Epigenetic Modifications in Ferroptosis

Ferroptosis is a non-apoptotic mode of cell death driven by membrane lipid peroxidation and is characterized by elevated intracellular levels of Fe2+, ROS, and lipid peroxidation. Studies have shown that ferroptosis is related to the development of multiple diseases, such as cancer, neurodegenerative diseases, and acute myeloid leukemia. Ferroptosis plays a dual role in the occurrence and development of these diseases. Ferroptosis mainly involves iron metabolism, ROS, and lipid metabolism. Various mechanisms, including epigenetic regulation, have been reported to be deeply involved in ferroptosis. Abnormal epigenetic modifications have been reported to promote tumor onset or other diseases and resistance to chemotherapy drugs. In recent years, diversified studies have shown that epigenetic modification is involved in ferroptosis. In this review, we reviewed the current resistance system of ferroptosis and the research progress of epigenetic modification, such as DNA methylation, RNA methylation, non-coding RNAs, and histone modification in cancer and other diseases by regulating ferroptosis.

LncRNA-MUF: A Novel Oncogenic Star with Potential as a Biological Marker and Therapeutic Target for Gastrointestinal Malignancies

Gastrointestinal (GI) cancers pose a significant global health challenge, characterized by a high incidence and poor prognosis. The delayed detection and occurrence of metastasis contribute to the overall low survival rates associated with these cancers. Therefore, there is an urgent need to identify novel molecular targets for effective GI cancer treatment. Recent research has shed light on the potential of long non-coding RNAs (lncRNAs) as promising targets in cancer therapy, given their strong association with carcinogenesis and profound impact on tumor development. Among these lncRNAs, lncRNA-MUF, also known as LINC00941, has emerged as a key player in oncogenic regulation, specifically implicated in the progression of various GI cancers, including esophageal, gastric, colorectal, hepatic, and pancreatic cancer. This review aims to provide an updated and focused analysis of the regulatory roles of LINC00941 in the initiation and progression of GI cancer. Our objective is to unravel the underlying molecular mechanisms through which LINC00941 influences GI cancer phenotypes both in vivo and in vitro, with a special emphasis on the key molecules and signaling pathways involved. Additionally, LINC00941 has demonstrated clinical significance in terms of clinical pathology, prognosis, and diagnosis in GI tumors, further reinforcing its potential as a novel therapeutic target.

The Potential Role of Non-coding RNAs in Regulating Ferroptosis in Cancer: Mechanisms and Application Prospects

Cancer is the second leading cause of death globally. Despite some successes, conventional cancer treatments are insufficient to address the growing problem of drug resistance in tumors and to achieve efficient treatment outcomes. Therefore, there is an urgent need to explore new therapeutic options. Ferroptosis, a type of iron- and reactive oxygen species-dependent regulated cell death, has been closely associated with cancer development and progression. Non-coding RNAs (ncRNAs) are a class of RNAs that do not code for proteins, and studies have demonstrated their involvement in the regulation of ferroptosis in cancer. This review aims to explore the molecular regulatory mechanisms of ncRNAs involved in ferroptosis in cancer and to emphasize the feasibility of ferroptosis and ncRNAs as novel therapeutic strategies for cancer. We conducted a systematic and extensive literature review using PubMed, Google Scholar, Web of Science, and various other sources to identify relevant studies on ferroptosis, ncRNAs, and cancer. A deeper understanding of ferroptosis and ncRNAs could facilitate the development of new cancer treatment strategies.

Targeting LINC00152 activates cAMP/Ca2+/ferroptosis axis and overcomes tamoxifen resistance in ER+ breast cancer

Tamoxifen has been the mainstay therapy to treat early, locally advanced, and metastatic estrogen receptor-positive (ER+) breast cancer, constituting around 75% of all cases. However, emergence of resistance is common, necessitating the identification of novel therapeutic targets. Here, we demonstrated that long-noncoding RNA LINC00152 confers tamoxifen resistance via blocking tamoxifen-induced ferroptosis, an iron-mediated cell death. Mechanistically, inhibiting LINC00152 reduces the mRNA stability of phosphodiesterase 4D (PDE4D), leading to activation of cAMP/PKA/CREB axis and increased expression of TRPC1 Ca2+ channel. This causes cytosolic Ca2+ overload and generation of reactive oxygen species (ROS) that is, on one hand, accompanied by downregulation of FTH1, a member of the iron sequestration unit, thus increasing intracellular Fe2+ levels; and on the other hand, inhibition of the peroxidase activity upon reduced GPX4 and xCT levels. These ultimately induce lipid peroxidation and ferroptotic cell death in combination with tamoxifen. Overexpressing PDE4D rescues LINC00152 inhibition-mediated tamoxifen sensitization by de-activating the cAMP/Ca2+/ferroptosis axis. Importantly, high LINC00152 expression is significantly correlated with high PDE4D/low ferroptosis and worse survival in multiple cohorts of tamoxifen- or tamoxifen-containing endocrine therapy-treated ER+ breast cancer patients. Overall, we identified LINC00152 inhibition as a novel mechanism of ferroptosis induction and tamoxifen sensitization, thereby revealing LINC00152 and its effectors as actionable therapeutic targets to improve clinical outcome in refractory ER+ breast cancer.

The role of microRNA-185 in the pathogenesis of human diseases: A focus on cancer

MicroRNAs (miRNAs) are a widely-studied class of non-coding RNAs characterized by their short length (18-25 nucleotides). The precise functions of miRNAs are not well-elucidated; however, an increasing number of studies suggest their involvement in various physiologic processes and deregulation in pathologic conditions. miRNA-185 (miR-185) is among the mostly-studied miRNAs in human diseases, which is found to play putative roles in conditions like metabolic disorders, asthma, frailty, schizophrenia, and hepatitis. Notably, many cancer studies report the downregulation of miR-185 in cell lines, tumor tissues, and plasma specimens of patients, while it demonstrates a suppressing role on the malignant properties of cancer cells in vitro and in vivo. Accordingly, miR-185 can be considered a tumor suppressor miRNA in human malignancies, while a few studies also report inconsistent findings. Being suggested as a prognostic/diagnostic biomarker, mi-185 is also found to offer clinical potentials, particularly for early diagnosis and prediction of the prognosis of cancer patients. In this review, we have outlined the studies that have evaluated the functions and clinical significance of miR-185 in different human diseases with a particular focus on cancer.

Microneedle Array Encapsulated with Programmed DNA Hydrogels for Rapidly Sampling and Sensitively Sensing of Specific MicroRNA in Dermal Interstitial Fluid

Author: Please verify that the changes made to improve the English still retain your original meaning.Detection of microRNA (miRNA) in dermal interstitial fluid (ISF) has emerged as clinically useful in health status monitoring. However, it remains a great challenge owing to the difficult sampling and low abundance. Here, we report a DNA hydrogel microneedles (MNs) array to realize rapid enrichment and sensitive detection of miRNA in ISF. The MNs' patch consists of methacrylate hyaluronic acid (MeHA) equipped with a smart DNA circuit hydrogels' system (MeHA/DNA), in which an appropriate miRNA input enables triggering a cascading toehold-mediated DNA displacement reaction to catalytically cleave cross-linking points to generate amplified fluorescence (FL) for miRNA detection. The MeHA/DNA-MNs patch with high mechanical strength can extract adequate ISF in a short time (0.97 ± 0.2 mg in 5 min) in vivo because of its supreme water affinity. Additionally, the cascading toehold-mediated DNA displacement signal amplification reaction allows for sensitive detection of the low-abundant miRNAs down to 241.56 pM. The DNA hydrogels' MNs present potential for minimally invasive personalized diagnosis and real-time health monitoring in clinical applications.

Non-coding RNAs and ferroptosis: potential implications for cancer therapy

Ferroptosis is a recently defined form of regulated cell death, which is biochemically and morphologically distinct from traditional forms of programmed cell death such as apoptosis or necrosis. It is driven by iron, reactive oxygen species, and phospholipids that are oxidatively damaged, ultimately resulting in mitochondrial damage and breakdown of membrane integrity. Numerous cellular signaling pathways and molecules are involved in the regulation of ferroptosis, including enzymes that control the cellular redox status. Alterations in the ferroptosis-regulating network can contribute to the development of various diseases, including cancer. Evidence suggests that ferroptosis is commonly suppressed in cancer cells, allowing them to survive and progress. However, cancer cells which are resistant to common chemotherapeutic drugs seem to be highly susceptible to ferroptosis inducers, highlighting the great potential of pharmacologic modulation of ferroptosis for cancer treatment. Non-coding RNAs (ncRNAs) are considered master regulators of various cellular processes, particularly in cancer where they have been implicated in all hallmarks of cancer. Recent work also demonstrated their involvement in the molecular control of ferroptosis. Hence, ncRNA-based therapeutics represent an exciting alternative to modulate ferroptosis for cancer therapy. This review summarizes the ncRNAs implicated in the regulation of ferroptosis in cancer and highlights their underlying molecular mechanisms in the light of potential therapeutic applications.

MiR-556-5p modulates migration, invasion, and epithelial-mesenchymal transition in breast cancer cells via targeting PTHrP

Breast cancer bone metastases may block normal bone remodeling and promote bone degradation, during which several signaling pathways and small non-coding miRNAs might all play a role. miRNAs and target mRNAs that might be associated with breast cancer bone metastasis were analyzed and selected using bioinformatics analyses based on online data. The 3' untranslated region of key factors associated with breast cancer metastasis were examined for candidate miRNA binding site using Targetscan. The predicted binding was validated. The specific effects of single miRNA and dynamic effects of the miRNA-mRNA axis on breast cancer cell metastasis were investigated. miR-556-5p was downregulated in breast cancer samples according to online datasets and experimental analyses. In breast cancer cells, miR-556-5p overexpression inhibited, whereas miR-556-5p inhibition promoted cancer cell invasion and migration. Among key factors associated with breast cancer bone metastasis, parathyroid hormone related protein (PTHrP) 3'UTR possessed miR-556-5p binding site. Through direct binding, miR-556-5p negatively regulated PTHrP expression. In breast cancer cell lines, miR-556-5p inhibition promoted, whereas PTHrP silencing suppressed cancer cell migration, invasion, and epithelial-mesenchymal transition; the effects of miR-556-5p inhibition were partially reversed by PTHrP silencing. In summary, miR-556-5p targets PTHrP to modulate the cell migration and invasion of breast cancer.

Identification of putative regulatory regions and transcription factors associated with intramuscular fat content traits

Background

Integration of high throughput DNA genotyping and RNA-sequencing data allows for the identification of genomic regions that control gene expression, known as expression quantitative trait loci (eQTL), on a whole genome scale. Intramuscular fat (IMF) content and carcass composition play important roles in metabolic and physiological processes in mammals because they influence insulin sensitivity and consequently prevalence of metabolic diseases such as obesity and type 2 diabetes. However, limited information is available on the genetic variants and mechanisms associated with IMF deposition in mammals. Thus, our hypothesis was that eQTL analyses could identify putative regulatory regions and transcription factors (TFs) associated with intramuscular fat (IMF) content traits.

Results

We performed an integrative eQTL study in skeletal muscle to identify putative regulatory regions and factors associated with intramuscular fat content traits. Data obtained from skeletal muscle samples of 192 animals was used for association analysis between 461,466 SNPs and the transcription level of 11,808 genes. This yielded 1268 cis- and 10,334 trans-eQTLs, among which we identified nine hotspot regions that each affected the expression of > 119 genes. These putative regulatory regions overlapped with previously identified QTLs for IMF content. Three of the hotspots respectively harbored the transcription factors USF1, EGR4 and RUNX1T1, which are known to play important roles in lipid metabolism. From co-expression network analysis, we further identified modules significantly correlated with IMF content and associated with relevant processes such as fatty acid metabolism, carbohydrate metabolism and lipid metabolism.

Conclusion

This study provides novel insights into the link between genotype and IMF content as evident from the expression level. It thereby identifies genomic regions of particular importance and associated regulatory factors. These new findings provide new knowledge about the biological processes associated with genetic variants and mechanisms associated with IMF deposition in mammals.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4871-y) contains supplementary material, which is available to authorized users.

Toward dynamic structural biology: Two decades of single-molecule Förster resonance energy transfer

Classical structural biology can only provide static snapshots of biomacromolecules. Single-molecule Förster resonance energy transfer (smFRET) paved the way for studying dynamics in macromolecular structures under biologically relevant conditions. Since its first implementation in 1996, smFRET experiments have confirmed previously hypothesized mechanisms and provided new insights into many fundamental biological processes, such as DNA maintenance and repair, transcription, translation, and membrane transport. We review 22 years of contributions of smFRET to our understanding of basic mechanisms in biochemistry, molecular biology, and structural biology. Additionally, building on current state-of-the-art implementations of smFRET, we highlight possible future directions for smFRET in applications such as biosensing, high-throughput screening, and molecular diagnostics.

Preliminary evaluation of circulating microRNAs as potential biomarkers in paracoccidioidomycosis

MicroRNAs (miRNAs) are small RNAs (length, 19-24 nucleotides) that regulate gene expression by either mRNA degradation or translational inhibition of proteins. Circulating miRNAs, which are extremely stable and protected from RNAse-mediated degradation in body fluids, have appeared as candidate biomarkers for numerous diseases. However, little is known about circulating miRNAs in fungal infections. Paracoccidioidomycosis (PCM) is caused by the Paracoccidioides species, and is endemic in Central and South America, with predominance in adult male workers from rural areas. The current study aimed to identify a serum miRNA expression profile that could serve as a novel diagnostic biomarker for PCM. Total RNA was isolated and the levels of circulating miRNAs were compared between patients with PCM and healthy control subjects using reverse transcription-quantitative polymerase chain reaction. Bioinformatic analysis was used to evaluate the potential roles of these miRNAs in PCM. Eight miRNAs were differentially expressed in serum samples from patients with PCM. These miRNAs are associated with apoptosis and immune response. The identified miRNAs facilitate with understanding the regulatory mechanisms involved in the host-parasite interaction of PCM. Furthermore, considering that the diagnosis of PCM presents difficulties, these miRNAs may serve as novel biomarkers for this disease.

Epigenetics of the failing heart

With the impressive advancement in high-throughput 'omics' technologies over the past two decades, epigenetic mechanisms have emerged as the regulatory interface between the genome and environmental factors. These mechanisms include DNA methylation, histone modifications, ATP-dependent chromatin remodeling and RNA-based mechanisms. Their highly interdependent and coordinated action modulates the chromatin structure controlling access of the transcription machinery and thereby regulating expression of target genes. Given the rather limited proliferative capability of human cardiomyocytes, epigenetic regulation appears to play a particularly important role in the myocardium. The highly dynamic nature of the epigenome allows the heart to adapt to environmental challenges and to respond quickly and properly to cardiac stress. It is now becoming evident that histone-modifying and chromatin-remodeling enzymes as well as numerous non-coding RNAs play critical roles in cardiac development and function, while their dysregulation contributes to the onset and development of pathological cardiac remodeling culminating in HF. This review focuses on up-to-date knowledge about the epigenetic mechanisms and highlights their emerging role in the healthy and failing heart. Uncovering the determinants of epigenetic regulation holds great promise to accelerate the development of successful new diagnostic and therapeutic strategies in human cardiac disease.

MicroRNA-30c-1-3p is a silencer of the pregnane X receptor by targeting the 3'-untranslated region and alters the expression of its target gene cytochrome P450 3A4

The pregnane X receptor (PXR) is a master regulator of genes involved in drug elimination. Recently, activation of PXR has also been linked to the development of many disease conditions such as metabolic disorders and malignancies. MicroRNAs (miRs) emerge as important molecular species involved in these conditions. This study was undertaken to test a large number of miRs for their ability to regulate PXR expression. As many as 58 miRs were tested and miR-30c-1-3p was identified to suppress PXR expression. The suppression was achieved by targeting the 3'-untranslated region, 438 nucleotides from the stop codon. The suppression was detected in multiple cell lines from different organ origins. In addition, miR-30c-1-3p altered basal and induced expression of cytochrome P450 3A4 (CYP3A4), a prototypical target gene of PXR. The alteration varied depending on the time and amounts of miR-30c-1-3p. CYP3A4 is responsible for the metabolism of more than 50% medicines. The interconnection between miR-30c-1-3p and PXR signifies a role of miRs in drug-drug interactions and chemosensitivity. This article is part of a Special Issue entitled: Xenobiotic nuclear receptors: New Tricks for An Old Dog, edited by Dr. Wen Xie.

Noncoding Regulatory RNAs in Hematopoiesis

Hematopoiesis is a dynamic process in which blood cells are continuously generated from hematopoietic stem cells (HSCs). The regulatory mechanisms controlling HSC fate have been studied extensively over the past several decades. Although many protein-coding genes have been shown to regulate hematopoietic differentiation, additional levels of HSC regulation are not well studied. Advances in deep sequencing have revealed many new classes of regulatory noncoding RNAs (ncRNAs), such as enhancer RNAs and antisense ncRNAs. Functional analysis of some of these ncRNAs has provided insights into the molecular mechanisms that regulate hematopoietic development and disease. In this review, we summarize recent advances in our understanding of functional regulatory ncRNAs associated with hematopoietic self-renewal and differentiation, as well as those dysregulated ncRNAs involved in hematologic malignancies.

Causes of genome instability: the effect of low dose chemical exposures in modern society

Genome instability is a prerequisite for the development of cancer. It occurs when genome maintenance systems fail to safeguard the genome's integrity, whether as a consequence of inherited defects or induced via exposure to environmental agents (chemicals, biological agents and radiation). Thus, genome instability can be defined as an enhanced tendency for the genome to acquire mutations; ranging from changes to the nucleotide sequence to chromosomal gain, rearrangements or loss. This review raises the hypothesis that in addition to known human carcinogens, exposure to low dose of other chemicals present in our modern society could contribute to carcinogenesis by indirectly affecting genome stability. The selected chemicals with their mechanisms of action proposed to indirectly contribute to genome instability are: heavy metals (DNA repair, epigenetic modification, DNA damage signaling, telomere length), acrylamide (DNA repair, chromosome segregation), bisphenol A (epigenetic modification, DNA damage signaling, mitochondrial function, chromosome segregation), benomyl (chromosome segregation), quinones (epigenetic modification) and nano-sized particles (epigenetic pathways, mitochondrial function, chromosome segregation, telomere length). The purpose of this review is to describe the crucial aspects of genome instability, to outline the ways in which environmental chemicals can affect this cancer hallmark and to identify candidate chemicals for further study. The overall aim is to make scientists aware of the increasing need to unravel the underlying mechanisms via which chemicals at low doses can induce genome instability and thus promote carcinogenesis.

Analysis of the differential expression of circulating microRNAs during the progression of hepatic fibrosis in patients with chronic hepatitis B virus infection

Considering the limitations of liver biopsy, reliable non‑invasive serum biomarkers of liver fibrosis are required for early diagnosis. The present study analyzed the expression profile of circulating micro (mi)RNAs during the development and progression of hepatic fibrosis in patients with chronic hepatitis B virus (HBV) infection, aiming to identify novel earlier diagnostic biomarkers. Fresh plasma samples were collected from 50 patients diagnosed with chronic HBV infection and hepatic fibrosis. These patients were classified into five groups (S0, S1, S2, S3 and S4; n=10 per group) based on Scheuer's staging criteria. The differential expression of the circulating miRNAs was determined by performing miRNA microarray hybridization. Finally, the target genes of the miRNAs were predicted and classified using gene ontology analysis. A total of 140 miRNAs were detected in the S1‑S4 patient groups, and their expression levels were >2‑fold higher compared with those in the S0 group. The numbers of miRNAs differentially expressed in the S1‑S4 patient groups were 48, 97, 84 and 56, respectively, with 12 miRNAs differentially expressed at all stages, 10 of which were upregulated and two of which were downregulated. The target genes of the miRNAs identified were found to be involved in 100 signal transduction pathways, the majority of which affected hepatic fibrosis via the TGF‑/Smad, Wnt, MAPK, Jak/STAT and VEGF pathways. The differential expression levels of miRNAs were closely associated with the staging of hepatic fibrosis. The results of the present study provide evidence to facilitate the development and application of non‑invasive biomarkers for earlier diagnosis of hepatic fibrosis.

Basic biology and therapeutic implications of lncRNA

Long non-coding RNAs (lncRNA), a class of non-coding RNA molecules recently identified largely due to the efforts of FANTOM, and later GENCODE and ENCODE consortia, have been a subject of intense investigation in the past decade. Extensive efforts to get deeper understanding of lncRNA biology have yielded evidence of their diverse structural and regulatory roles in protecting chromosome integrity, maintaining genomic architecture, X chromosome inactivation, imprinting, transcription, translation and epigenetic regulation. Here we will briefly review the recent studies in the field of lncRNA biology focusing mostly on mammalian species and discuss their therapeutic implications.

Circulating microRNAs: emerging biomarkers for diagnosis and prognosis in patients with gastrointestinal cancers

To identify novel non-invasive biomarkers for improved detection, risk assessment and prognostic evaluation of cancer, expression profiles of circulating microRNAs are currently under evaluation. Circulating microRNAs are highly promising candidates in this context, as they present some key characteristics for cancer biomarkers: they are tissue-specific with reproducible expression and consistency among individuals from the same species, they are potentially derived directly from the tumour and therefore might correlate with tumour progression and recurrence, and they are bound to proteins or contained in subcellular particles, such as microvesicles or exosomes, making them highly stable and resistant to degradation. The present review highlights the origin of circulating microRNAs, their stability in blood samples, and techniques to isolate exosomal microRNAs, and then addresses the current evidence supporting potential clinical applications of circulating miRNAs for diagnostic and prognostic purposes.

MicroRNAs: Promising chemoresistance biomarkers in gastric cancer with diagnostic and therapeutic potential

Gastric cancer (GC) is the fourth most common cancer worldwide and ranks second in global cancer mortality statistics. Perioperative chemotherapy plays an important role in the management and treatment of advanced stage disease. However, response to chemotherapy varies widely, with some patients presenting no or only minor response to treatment. Hence, chemotherapy resistance is a major clinical problem that impacts on outcome. Unfortunately, to date there are no reliable biomarkers available that predict response to chemotherapy before the start of the treatment, or that allow modification of chemotherapy resistance. MicroRNAs (miRNAs) could provide an answer to this problem. miRNAs are involved in the initiation and progression of a variety of cancer types, and there is evidence that miRNAs impact on resistance towards chemotherapeutic drugs as well. This current review aims to provide an overview about the potential clinical applicability of miRNAs as biomarkers for chemoresistance in GC. The authors focus in this context on the potential of miRNAs to predict sensitivity towards different chemotherapeutics, and on the potential of miRNAs to modulate sensitivity and resistance towards chemotherapy in GC.

ptRNApred: computational identification and classification of post-transcriptional RNA

Non-coding RNAs (ncRNAs) are known to play important functional roles in the cell. However, their identification and recognition in genomic sequences remains challenging. In silico methods, such as classification tools, offer a fast and reliable way for such screening and multiple classifiers have already been developed to predict well-defined subfamilies of RNA. So far, however, out of all the ncRNAs, only tRNA, miRNA and snoRNA can be predicted with a satisfying sensitivity and specificity. We here present ptRNApred, a tool to detect and classify subclasses of non-coding RNA that are involved in the regulation of post-transcriptional modifications or DNA replication, which we here call post-transcriptional RNA (ptRNA). It (i) detects RNA sequences coding for post-transcriptional RNA from the genomic sequence with an overall sensitivity of 91% and a specificity of 94% and (ii) predicts ptRNA-subclasses that exist in eukaryotes: snRNA, snoRNA, RNase P, RNase MRP, Y RNA or telomerase RNA.

AVAILABILITY

The ptRNApred software is open for public use on http://www.ptrnapred.org/.

Certain adenylated non-coding RNAs, including 5' leader sequences of primary microRNA transcripts, accumulate in mouse cells following depletion of the RNA helicase MTR4

RNA surveillance plays an important role in posttranscriptional regulation. Seminal work in this field has largely focused on yeast as a model system, whereas exploration of RNA surveillance in mammals is only recently begun. The increased transcriptional complexity of mammalian systems provides a wider array of targets for RNA surveillance, and, while many questions remain unanswered, emerging data suggest the nuclear RNA surveillance machinery exhibits increased complexity as well. We have used a small interfering RNA in mouse N2A cells to target the homolog of a yeast protein that functions in RNA surveillance (Mtr4p). We used high-throughput sequencing of polyadenylated RNAs (PA-seq) to quantify the effects of the mMtr4 knockdown (KD) on RNA surveillance. We demonstrate that overall abundance of polyadenylated protein coding mRNAs is not affected, but several targets of RNA surveillance predicted from work in yeast accumulate as adenylated RNAs in the mMtr4KD. microRNAs are an added layer of transcriptional complexity not found in yeast. After Drosha cleavage separates the pre-miRNA from the microRNA's primary transcript, the byproducts of that transcript are generally thought to be degraded. We have identified the 5′ leading segments of pri-miRNAs as novel targets of mMtr4 dependent RNA surveillance.

Noncoding RNAs in endocrine malignancy

Only recently has it been uncovered that the mammalian transcriptome includes a large number of noncoding RNAs (ncRNAs) that play a variety of important regulatory roles in gene expression and other biological processes. Among numerous kinds of ncRNAs, short noncoding RNAs, such as microRNAs, have been extensively investigated with regard to their biogenesis, function, and importance in carcinogenesis. Long noncoding RNAs (lncRNAs) have only recently been implicated in playing a key regulatory role in cancer biology. The deregulation of ncRNAs has been demonstrated to have important roles in the regulation and progression of cancer development. In this review, we describe the roles of both short noncoding RNAs (including microRNAs, small nuclear RNAs, and piwi-interacting RNAs) and lncRNAs in carcinogenesis and outline the possible underlying genetic mechanisms, with particular emphasis on clinical applications. The focus of our review includes studies from the literature on ncRNAs in traditional endocrine-related cancers, including thyroid, parathyroid, adrenal gland, and gastrointestinal neuroendocrine malignancies. The current and potential future applications of ncRNAs in clinical cancer research is also discussed, with emphasis on diagnosis and future treatment.

Exponential strand-displacement amplification for detection of microRNAs

MicroRNAs (miRNAs) are promising targets for disease diagnosis. However, miRNA detection requires rapid, sensitive, and selective detection to be effective as a diagnostic tool. Herein, a miRNA-initiated exponential strand-displacement amplification (SDA) assay was reported. With the Klenow fragment, nicking enzyme Nt.AlwI, and two primers, the miRNA target can trigger two cycles of nicking, polymerization, and displacement reactions. These reaction cycles amplified the target miRNA exponentially and generated dsDNAs detectable with SYBR Green I in real-time PCR. As low as 16 zmol of the target miRNA was detected by this one-pot assay within 90 min, and the dynamic range spanned over 9 orders of magnitude. Negligible impact from the complex biological matrix was observed on the amplification reaction, indicating the assay's capability to directly detect miRNAs in biofluids.

Biases in small RNA deep sequencing data

High-throughput RNA sequencing (RNA-seq) is considered a powerful tool for novel gene discovery and fine-tuned transcriptional profiling. The digital nature of RNA-seq is also believed to simplify meta-analysis and to reduce background noise associated with hybridization-based approaches. The development of multiplex sequencing enables efficient and economic parallel analysis of gene expression. In addition, RNA-seq is of particular value when low RNA expression or modest changes between samples are monitored. However, recent data uncovered severe bias in the sequencing of small non-protein coding RNA (small RNA-seq or sRNA-seq), such that the expression levels of some RNAs appeared to be artificially enhanced and others diminished or even undetectable. The use of different adapters and barcodes during ligation as well as complex RNA structures and modifications drastically influence cDNA synthesis efficacies and exemplify sources of bias in deep sequencing. In addition, variable specific RNA G/C-content is associated with unequal polymerase chain reaction amplification efficiencies. Given the central importance of RNA-seq to molecular biology and personalized medicine, we review recent findings that challenge small non-protein coding RNA-seq data and suggest approaches and precautions to overcome or minimize bias.

Epigenetic biomarkers in laboratory diagnostics: emerging approaches and opportunities

Epigenetics has emerged as a new and promising field in recent years. Lifestyle, stress, drugs, physiopathological situations and pharmacological interventions have a great impact on the epigenetic code of the cells by altering the methylome, miRNA expression and the covalent histone modifications. Since there exists a need to find new biomarkers and improve diagnosis for several diseases, the research on epigenetic biomarkers for molecular diagnostics encourages the translation of this field from the bench to clinical practice. In this context, deciphering intricate epigenetic modifications involved in several molecular processes is a challenge that will be solved in the near future. In this review, the authors present an overview of the high-throughput technologies and laboratory techniques available for epigenetic studies, and also discuss which of them are more reliable to be used in a clinical diagnostic laboratory. In addition, the authors describe the most promising epigenetic biomarkers in lung, colorectal and prostate cancer, in which most advances have been achieved. Finally, the authors describe epigenetic biomarkers in some rare diseases; these rare syndromes are paradigms for a specific impaired molecular pathway, thus providing valuable information on the discovery of new epigenetic biomarkers.

MiR-205 is progressively down-regulated in lymph node metastasis but fails as a prognostic biomarker in high-risk prostate cancer

The treatment of high-risk prostate cancer (HRPCa) is a tremendous challenge for uro-oncologists. The identification of predictive moleculobiological markers allowing risk assessment of lymph node metastasis and systemic progression is essential in establishing effective treatment. In the current study, we investigate the prognostic potential of miR-205 in HRPCa study and validation cohorts, setting defined clinical endpoints for both. We demonstrate miR-205 to be significantly down-regulated in over 70% of the HRPCa samples analysed and that reconstitution of miR-205 causes inhibition of proliferation and invasiveness in prostate cancer (PCa) cell lines. Additionally, miR-205 is increasingly down-regulated in lymph node metastases compared to the primary tumour indicating that miR-205 plays a role in migration of PCa cells from the original location into extraprostatic tissue. Nevertheless, down-regulation of miR-205 in primary PCa was not correlated to the synchronous presence of metastasis and failed to predict the outcome for HRPCa patients. Moreover, we found a tendency for miR-205 up-regulation to correlate with an adverse outcome of PCa patients suggesting a pivotal role of miR-205 in tumourigenesis. Overall, we showed that miR-205 is involved in the development and metastasis of PCa, but failed to work as a useful clinical biomarker in HRPCa. These findings might have implications for the use of miR-205 as a prognostic or therapeutic target in HRPCa.

Terminal dual-labeling of a transcribed RNA

We report here a site-specific terminal dual-labeling strategy for a transcribed RNA. The combination of 5'-thiophosphoryl and 3'-amino functionalities enables efficient RNA dual labeling with different fluorophores at both 5'- and 3'-terminal positions specifically. This dual-labeling strategy is applied to pre-miRNA for construction of molecular beacons. The RNA beacons in their native hairpin formation bring the fluorophore and quencher groups into close proximity, leading to fluorescence quenching by FRET effect. Ribonuclease (dicer enzyme or micrococcal nuclease) can efficiently cleave RNA beacons leading to concentration- and time-dependent fluorescence increase. The dual-labeling strategy for transcribed RNAs involves only commercially available reagents, enzymes and native RNA, making it more accessible for general applications.

Regulation of breast cancer and bone metastasis by microRNAs

Breast cancer progression including bone metastasis is a complex process involving numerous changes in gene expression and function. MicroRNAs (miRNAs) are small endogenous noncoding RNAs that regulate gene expression by targeting protein-coding mRNAs posttranscriptionally, often affecting a number of gene targets simultaneously. Alteration in expression of miRNAs is common in human breast cancer, possessing with either oncogenic or tumor suppressive activity. The expression and the functional role of several miRNAs (miR-206, miR-31, miR-27a/b, miR-21, miR-92a, miR-205, miR-125a/b, miR-10b, miR-155, miR-146a/b, miR-335, miR-204, miR-211, miR-7, miR-22, miR-126, and miR-17) in breast cancer has been identified. In this review we summarize the experimentally validated targets of up- and downregulated miRNAs and their regulation in breast cancer and bone metastasis for diagnostic and therapeutic purposes.