Genomewide Study of Salivary MicroRNAs for Detection of Oral Cancer

Salivary micro RNA as a potential biomarker in oral potentially malignant disorders: A systematic review

Oral potentially malignant disorders (OPMD) are oral mucosal disorders which have a high potential to turn into malignancy. A recent report suggests that 16%–62% of epithelial dysplasia cases of OPMD undergo malignant transformation, showing the need for early detection of malignancy in these disorders. Micro RNA (miRNA) plays an important role in cellular growth, differentiation, apoptosis, and immune response, and hence, deregulation of miRNA is considered a signature of oral carcinogenesis. A search was done using MeSH terms in the PubMed, ScienceDirect databases, hand search, and finally, six studies were included in this systematic review. A total of 167 patients with oral cancer, 78 with OPMDs, 147 healthy controls, and 20 disease controls were analyzed for the expression of salivary miRNAs. Quality assessment based on the Quality Assessment of Diagnostic Accuracy Studies 2 tool was used to obtain a risk of bias chart using Revman 5.3 software and it was proved that the study done by Zahran et al. in 2015 had a low risk of bias. The results of this study revealed upregulated miRNA 184 with an area under the curve (AUC) of 0.86 and miRNA 21 with an AUC of 0.73 and downregulated miRNA 145 with an AUC of 0.68, which proved that these miRNAs are significant in detecting early malignancy in OPMD and should be further analyzed in various populations. This systematic review explored the potential of expression of salivary miRNA in OPMD for future studies. This could pave the way to utilize saliva as a surrogate marker in diagnosing early malignant changes in OPMD.

Assessing miRNAs profile expression as a risk stratification biomarker in oral potentially malignant disorders: A systematic review

OBJECTIVES

This paper aims to systematically review current findings on altered expression of miRNAs in OPMDs and whether they can be used as risk stratification biomarkers.

METHODS

Studies were collated after searching three different electronic databases: PubMed, Embase, Medline. Additional searches were carried out through cross checking the bibliographies of selected articles. After a thorough selection process made by two of the authors, 40 articles met the inclusion criteria and were included in the review. Studies were assessed and analysed in terms of how the candidate miRNA biomarkers were differentially expressed and validated.

RESULTS

The included studies examined the expression of miRNAs from human specimens (blood serum/plasma, saliva, tissue) as diagnostic or prognostic biomarkers in patients with OPMDs, some of which have been utilised as risk stratification biomarkers for malignant transformation and have showed promising findings.

CONCLUSION

The current evidence to support or refute the prognostic utility of miRNAs in predicting cancer progression in OPMDs is equivocal. Further longitudinal prospective studies with solid study design are warranted.

Role of microRNAs in embryo implantation

Failure of embryo implantation is a major limiting factor in early pregnancy and assisted reproduction. Determinants of implantation include the embryo viability, the endometrial receptivity, and embryo-maternal interactions. Multiple molecules are involved in the regulation of implantation, but their specific regulatory mechanisms remain unclear. MicroRNA (miRNA), functioning as the transcriptional regulator of gene expression, has been widely reported to be involved in embryo implantation. Recent studies reveal that miRNAs not only act inside the cells, but also can be released by cells into the extracellular environment through multiple packaging forms, facilitating intercellular communication and providing indicative information associated with physiological and pathological conditions. The discovery of extracellular miRNAs shed new light on implantation studies. MiRNAs provide new mechanisms for embryo-maternal communication. Moreover, they may serve as non-invasive biomarkers for embryo selection and assessment of endometrial receptivity in assisted reproduction, which improves the accuracy of evaluation while reducing the mechanical damage to the tissue. In this review, we discuss the involvement of miRNAs in embryo implantation from several aspects, focusing on the role of extracellular miRNAs and their potential applications in assisted reproductive technologies (ART) to promote fertility efficiency.

Serum, plasma and saliva biomarkers for head and neck cancer

INTRODUCTION

Head and neck squamous cell carcinoma (HNSCC) encompasses tumors arising from several locations (oral and nasal cavities, paranasal sinuses, salivary glands, pharynx, and larynx) and currently stands as the sixth most common cancer worldwide. The most important risk factors identified so far are tobacco and alcohol consumption, and, for a subgroup of HNSCCs, infection with high-risk types of human papillomavirus (HPV). Despite several improvements in the treatment of these tumors in the last decades, overall survival rates have only improved marginally, mainly due to the advanced clinical stage at diagnosis and the high rates of treatment failure associated with this late diagnosis. Areas covered: This review will focus on the feasibility of evaluating molecular-based biomarkers (mRNA, microRNA, lncRNA, DNA methylation and protein expression) in body fluids (serum, plasma, and saliva) as markers for diagnosis, prognosis, and surveillance. Expert commentary: The potential use of those markers in the clinical setting would allow for early diagnosis, prediction of treatment response, improvement in treatment selection and provide disease monitoring for early detection of tumor recurrence. It can ultimately be translated into better survival rates and improved quality of life for HNSCC patients.

Cell-free nucleic acids in body fluids as biomarkers for the prediction and early detection of recurrent head and neck cancer: A systematic review of the literature

Liquid biopsy is a minimally invasive detection method for molecular biomarkers in body fluids which may serve as a novel tool in management of head and neck cancer. The purpose of this systematic review is to outline the current status of liquid biopsy in head and neck squamous cell carcinoma (HNSCC) patients by systematically identifying and qualifying all published studies on the diagnostic or prognostic value of cell-free nucleic acids detection for posttreatment disease monitoring and/or disease outcome. A search was performed in PubMed, EMBASE, and Cochrane Library. Thirty articles met the inclusion criteria for further analysis. Study and patient characteristics, molecular analysis method and treatment or prognostic outcomes were extracted. Seventeen studies investigated circulating miRNAs in blood. Of these studies, 16 found statistically significant results for a total of 24 different candidate miRNAs for prognostication or treatment monitoring. The remaining studies investigated circulating tumor DNA by targeting somatic mutations, allelic imbalances, hypermethylation, or HPV-DNA. Of these studies, 2 found a statistically significant association between nucleic acid levels (tumor DNA targeted by allelic imbalances and HPV-DNA) in blood and/or saliva and prognostic outcome. One study found significantly different pre- and posttreatment levels of mitochondrial DNA in serum. Despite large differences among these studies in both design and results, individual results are promising and provide ground for more large-scale studies with standardized serial assessment of patient samples in the future.

Downregulation of miR‑136‑5p in hepatocellular carcinoma and its clinicopathological significance

The clinical significance of microRNA (miR)‑136‑5p in hepatocellular carcinoma (HCC) has not been verified. Therefore, in the current study, the authors aimed to explore miR‑136‑5p expression and its clinical significance in HCC, as well as to investigate its potential target genes function. The authors detected the levels of miR‑136‑5p in 101 pairs of HCC and para‑cancer tissues via reverse transcription‑quantitative polymerase chain reaction. Gene Expression Omnibus database and the Cancer Genome Atlas (TCGA) database were used to further verify the clinical significance of miR‑136‑5p expression in HCC. The target genes prediction analysis of miR‑136‑5p, natural language processing (NLP) analysis of HCC in PubMed and gene functional enrichment analysis were conducted. The miR‑136‑5p level was markedly downregulated in HCC tissue, compared to para‑non‑tumor tissue. MiR‑136‑5p expression decreased in HCC patients with metastasis (P=0.004), advance TNM stage (P<0.001), portal vein tumor embolus (P=0.007) and vaso‑invasion (P=0.003), compared with those HCC patients with non‑metastasis, early TNM stage, non‑portal vein tumor embolus and non‑vaso‑invasion, respectively. In the TCGA database, downregulated miR‑136‑5p was also observed in HCC tissue compared to normal liver tissue (P<0.001). There were 178 genes obtained from the overlap between predicted targets and NLP analysis. GO and KEGG pathway analyses revealed some significant pathways related to cancers. Downregulation of miR‑136‑5p may be responsible for the carcinogenesis and aggressiveness of HCC. miR‑136‑5p may act as an anti‑carcinoma miRNA, which is essential for HCC progression through the regulation of various signaling pathways. Thus, miR‑136‑5p interaction may provide a novel strategy for HCC treatment.

Oral Health: The Need for Both Conventional Microbial and Molecular Characterization

This study aims to consider the microbial distribution in oral disease, as well as gene analysis and expression, in elucidating: 1, the fundamental underpinnings of oral disease, and 2, the potential relationship between oral diseases and systemic health. A key focus is identifying the microbiota associated with oral disease manifestations characterized by both conventional microbiological and molecular methods. Variations in the observed microbial populations characterized by conventional and molecular approaches have been identified for caries, periodontitis, peri-implantitis, and stomatitis. The discovery of therapeutic approaches for oral disease will require comprehensive microbial and genomic analysis. This study evaluated the current state of the relevant microbial and genomic information for several prevalent oral diseases.

MicroRNA-335-5p Plays Dual Roles in Periapical Lesions by Complex Regulation Pathways

INTRODUCTION

MicroRNA-335-5p has been reported to regulate osteogenic and chondrogenic differentiations of mesenchymal stem cells. The aim of this study was to explore the function and regulation mechanism of miR-335-5p in apical periodontitis (AP).

METHODS

Total RNAs were extracted from human periodontal ligament fibroblasts (HPDLFs), 10 AP tissues, and 6 healthy periodontal ligament tissues using lysis buffer. Gene expression was detected using real-time polymerase chain reaction. The Dual Luciferase Assay (Promega, Madison, WI) was used to test miR-335-5p directly targeted urokinase-type plasminogen activator receptor (uPAR) and the receptor activator of nuclear factor kappa-B ligand (RANKL). Western Blot was used to detect protein expressions of RANKL, uPAR, and the fragile X-related 1 gene (FXR1). The enzyme-linked immunosorbent assay was used to detect the secretions of interleukin 6, tumor necrosis factor alpha, and RANKL. Data were analyzed using the Student t test.

RESULTS

miR-335-5p acted as a positive mediator in HPDLF inflammation (P < .05). Two targets of miR-335-5p, uPAR and RANKL, were identified. Interestingly, uPAR was repressed by miR-335-5p at the basal level, but it can be relieved from miR-335-5p-mediated repression, which is called derepression, when HPDLFs were subjected to lipopolysaccharide stimulation. miR-335-5p promoted RANKL in HPDLFs regardless of whether or not it was under inflammatory conditions (P < .05). We proved FXR1 was responsible for the derepression of uPAR from miR-335-5p (P < .01). Both FXR1 and uPAR were positive mediators in HPDLF inflammation (P < .05). miR-335-5p, uPAR, RANKL, and FXR1 had the same expression profiles in HPDLF inflammation and AP tissues (P < .05).

CONCLUSIONS

Our data showed that miR-335-5p may play dual roles in AP, and it might be considered as a target for therapeutic potency in clinical applications.

Improving accuracy of RNA-based diagnosis and prognosis of oral cancer by using noninvasive methods

RNA-based diagnosis and prognosis of squamous cell carcinoma has been slow to come to the clinic. Improvements in RNA measurement, statistical evaluation, and sample preservation, along with increased sample numbers, have not made these methods reproducible enough to be used clinically. We propose that, in the case of squamous cell carcinoma of the oral cavity, a chief source of variability is sample dissection, which leads to variable amounts of stroma mixed in with tumor epithelium. This heterogeneity of the samples, which requires great care to avoid, makes it difficult to see changes in RNA levels specific to tumor cells. An evaluation of the data suggests that, paradoxically, brush biopsy samples of oral lesions may provide a more reproducible method than surgical acquisition of samples for miRNA measurement. The evidence also indicates that body fluid samples can show similar changes in miRNAs with oral squamous cell carcinoma (OSCC) as those seen in tumor brush biopsy samples - suggesting much of the miRNA in these samples is coming from the same source: tumor epithelium. We conclude that brush biopsy or body fluid samples may be superior to surgical samples in allowing miRNA-based diagnosis and prognosis of OSCC in that they feature a rapid method to obtain homogeneous tumor cells and/or RNA.

Promising therapeutic role of miR-27b in tumor

MicroRNAs are small nonprotein-encoding RNAs ranging from 18 to 25 nucleotides in size and regulate multiple biological pathways via directly targeting a variety of associated genes in cancers. MicroRNA-27b is a highly conserved MicroRNA throughout vertebrates and there are two homologs (hsa-miR-27a and hsa-miR-27b) in humans. MicroRNA-27b is an intragenic microRNA located on chromosome 9q22.1 within the C9orf3 gene, clustering with miR-23b and miR-24-1 in human. As a frequently dysregulated microRNA in human cancers, microRNA-27b could function as a tumor suppressor or an oncogenic microRNA. More and more studies indicate that microRNA-27b is involved in affecting various biological processes, such as angiogenesis, proliferation, metastasis, and drug resistance, and thus may act as a promising therapeutic target in human cancers. In this review, we discuss the role of microRNA-27b in detail and offer novel insights into molecular targeting therapy for cancers.

The oral cavity microbiota: between health, oral disease, and cancers of the aerodigestive tract

Many studies show that the human microbiome plays a critical role in the chronic pathologies of obesity, inflammatory bowel diseases, and diabetes. More recently, the interaction between cancer and the microbiome has been highlighted. Most studies have focused on the gut microbiota because it represents the most extensive bacterial community, and the body of evidence correlating it with gut syndromes is increasing. However, in the strict sense, the gastrointestinal (GI) tract begins in the oral cavity, and special attention should be paid to the specific flora of this cavity. This study reviewed the current knowledge about the various microbial ecosystems of the upper part of the GI tract and discussed their potential link to carcinogenesis. The overall composition of the microbial communities, as well as the presence or absence of "key species", in relation to carcinogenesis is addressed. Alterations in the oral microbiota can potentially be used to predict the risk of cancer. Molecular advances and the further monitoring of the microbiota will increase our understanding of the role of the microbiota in carcinogenesis and open new perspectives for future therapeutic and prophylactic modalities.

Integrated Analysis and MicroRNA Expression Profiling Identified Seven miRNAs Associated With Progression of Oral Squamous Cell Carcinoma

MicroRNAs have been used as diagnostic and prognostic biomarkers for many cancers including oral squamous cell carcinoma (OSCC). Several studies have been shown that microRNA (miRNA) play important roles during the progression of OSCC. However, the results vary largely in different studies due to different platforms and sample sizes. In this study, we systematically evaluated a large scale of miRNA profiles from current qualified OSCC samples, and further investigated the functions of genes regulated by these key miRNAs as well as the signaling pathways through which these miRNA effect carcinogenesis. Seven key miRNAs were identified, and of which three were significantly upregulated, including hsa-miR-21, hsa-miR-31, hsa-miR-338, and four were downregulated, namely hsa-miR-125b, hsa-miR-133a, hsa-miR-133b, and hsa-miR-139. The function enrichment analysis revealed that target genes of upregulated miRNAs were associated with cellular protein metabolic process, macromolecule metabolic process, and TGF-beta pathway, while the targets of downregulated were enriched in negative regulation of macromolecule biosynthetic process and gene expression, and p53, long-term potentiation and adherens junction pathways. Transcription factor analysis revealed that there were 67 (51.1%) transcription factors influenced by both up and downregulated miRNAs. In summary, seven key miRNAs were found to play essential role in progression of OSCC, as well as the target genes and transcription factors of these miRNAs. The potential functions of these target genes identified in our study may be profitable to diagnosis and prognostic prediction of OSCC as biomarkers. J. Cell. Physiol. 232: 2178-2185, 2017. © 2016 Wiley Periodicals, Inc.

miR clusters target cellular functional complexes by defining their degree of regulatory freedom

Using the two paralog miR-23∼27∼24 clusters as an example and combining experimental and clinical data in a systematical approach to microRNA (miR) function and dysregulation, a complex picture of their roles in cancer is drawn. Various findings appear to be contradictory to a larger extent and cannot be fully explained by the classical regulatory network models and feedback loops that are mainly considered by one-to-one regulatory interactions of the involved molecules. Here, we propose an extended model of the regulatory role of miRs that, at least, supplements the usually considered single/oligo-target regulation of certain miRs. The cellular availability of the participating miR members in this model reflects an upper hierarchy level of intracellular and extracellular environmental influences, such as neighboring cells, soluble factors, hypoxia, chemotherapeutic drugs, and irradiation, among others. The novel model is based on the understanding of cellular functional complexes, such as for apoptosis, migration, and proliferation. These complexes consist of many regulatory components that can be targeted by miR cluster members to a different extent but may affect the functional complex in different ways. We propose that the final miR-related effect is a result of the possible degree of regulatory freedom provided by the miR effects on the whole functional complex structure. This degree of regulatory freedom defines to which extent the cellular functional complex can react in response to regulatory triggers, also understood as sensitization (more regulatory response options) or de-sensitization (less regulatory response options) of the system rather than single molecules.

Oral swirl samples - a robust source of microRNA protected by extracellular vesicles

BACKGROUND

MicroRNAs are small non-coding RNAs which are dysregulated in disease states, such as oral cancer. Extracellular vesicles, a potential source of microRNA, are found in saliva.

OBJECTIVE

To demonstrate that a quantifiable amount of microRNA can be isolated from oral swirl samples. Additionally, we hypothesized that extracellular vesicles may protect contained microRNA from degradation in these samples.

METHOD

A polyethylene glycol-based precipitation was used for extracellular vesicle enrichment of oral swirl samples. Comparison was made between samples treated with and without RNase. Further, samples from three subjects were exposed to a range of conditions over 7 days and assessed for presence of microRNA by reverse-transcription quantitative PCR. Extracellular vesicles from samples were identified under transmission electron microscopy.

RESULTS

An adequate quantity of microRNA for qPCR analysis was extractable from samples despite exposure to conditions under which degradation of RNA would be expected.

CONCLUSION

A technique was developed to isolate an adequate quantity of microRNA for analysis from oral swirl samples. Extracellular vesicle-associated microRNA may be protected from degradation. This technique moves towards chairside application of translational microRNA research in the field of oral cancer prognostics.

microRNA from brush biopsy to characterize oral squamous cell carcinoma epithelium

Few cancers are diagnosed based on RNA expression signatures. Oral squamous cell carcinoma (OSCC) is no exception; it is currently diagnosed by scalpel biopsy followed by histopathology. This study sought to identify oral tumor epithelial microRNA (miRNA) expression changes to determine if these changes could be used to diagnose the disease noninvasively. Analysis of miRNA profiles from surgically obtained OSCC tissue, collected under highly standardized conditions for The Cancer Genome Atlas, was done to determine the potential accuracy in differentiating tumor from normal mucosal tissue. Even when using small 20 subject datasets, classification based on miRNA was 90 to 100% accurate. To develop a noninvasive classifier for OSSC, analysis of brush biopsy miRNA was done and showed 87% accuracy in differentiating tumor from normal epithelium when using RT‐qPCR or miRNAseq to measure miRNAs. An extensive overlap was seen in differentially expressed miRNAs in oral squamous cell carcinoma epithelium obtained using brush biopsy and those reported in saliva and serum of oral squamous cell carcinoma patients in several studies. This suggested that nonselective release of these miRNAs into body fluids from tumor epithelium was largely responsible for the changes in levels in these fluids seen with this disease. Using a variation in mirRPath we identified the KEGG pathway of neurotrophin signaling as a target of these miRNAs disregulated in tumor epithelium. This highlights the utility of brush biopsy of oral mucosa to allow simple acquisition of cancer relevant miRNA information from tumor epithelium.

The Potential Use of Salivary miRNAs as Promising Biomarkers for Detection of Cancer: A Meta-Analysis

BACKGROUND

Accumulating evidence has demonstrated that microRNAs (miRNAs) could serve as promising molecular biomarkers for cancer detection. This study aims to systematically assess the diagnostic performance of salivary miRNAs in detection of cancer through a comprehensive meta-analysis.

METHODS

Eligible studies were identified using PubMed and other computerized databases up to October 31, 2015, supplemented by a manual search of references from retrieved articles. The pooled sensitivity, specificity, and other measurements of accuracy of salivary miRNAs in the diagnosis of cancer were analyzed using the bivariate binomial mixed model.

RESULTS

Seventeen studies from 8 articles with 694 subjects were included in this meta-analysis. All studies have a relatively high score of quality assessment. The overall sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) of salivary miRNAs in detection of cancer were 0.77 (95% confidence intervals [CI]: 0.69-0.84), 0.77 (95%CI: 0.65-0.88), 3.37 (95%CI: 2.26-5.02), 0.29 (95%CI: 0.23-0.38), and 11.41 (95%CI: 7.35-17.73), respectively. The AUC was 0.84 (95%CI: 0.80-0.87). Moreover, both whole saliva and saliva supernatant could be used as sources of clinical specimens for miRNAs detection.

CONCLUSIONS

Our meta-analysis demonstrated that salivary miRNAs may serve as potential noninvasive biomarkers for cancer detection. The findings need to be confirmed with further research before it can be applied in the clinic.

Are circulating microRNAs peripheral biomarkers for Alzheimer's disease?

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by memory loss, multiple cognitive abnormalities and intellectual impairments. Currently, there are no drugs or agents that can delay and/or prevent the progression of disease in elderly individuals, and there are no peripheral biomarkers that can detect AD early in its pathogenesis. Research has focused on identifying biomarkers for AD so that treatment can be begun as soon as possible in order to restrict or prevent intellectual impairments, memory loss, and other cognitive abnormalities that are associated with the disease. One such potential biomarker is microRNAs that are found in circulatory biofluids, such as blood and blood components, serum and plasma. Blood and blood components are primary sources where miRNAs are released in either cell-free form and then bind to protein components, or are in an encapsulated form with microvesicle particles. Exosomal miRNAs are known to be stable in biofluids and can be detected by high throughput techniques, like microarray and RNA sequencing. In AD brain, enriched miRNAs encapsulated with exosomes crosses the blood brain barrier and secreted in the CSF and blood circulations. This review summarizes recent studies that have identified miRNAs in the blood, serum, plasma, exosomes, cerebral spinal fluids, and extracellular fluids as potential biomarkers of AD. Recent research has revealed only six miRNAs - miR-9, miR-125b, miR-146a, miR-181c, let-7g-5p, and miR-191-5p - that were reported by multiple investigators. Some studies analyzed the diagnostic potential of these six miRNAs through receiver operating curve analysis which indicates the significant area-under-curve values in different biofluid samples. miR-191-5p was found to have the maximum area-under-curve value (0.95) only in plasma and serum samples while smaller area-under-curve values were found for miR-125, miR-181c, miR-191-5p, miR-146a, and miR-9. This article shortlisted the promising miRNA candidates and discussed their diagnostic properties and cellular functions in order to search for potential biomarker for AD.

Molecular Changes Involving MEK3-p38 MAPK Activation in Chronic Masticatory Myalgia

The exact mechanism underlying chronic masticatory myalgia (CMM), a conspicuous symptom in temporomandibular disorders, remains unclear. This investigation compared gene expression profiles between CMM patients and healthy subjects. Peripheral blood leukocytes were collected in 8 cases and 8 controls and subjected to whole genome microarray analyses. Data were analyzed with Gene Ontology and interactive pathways analyses. According to Gene Ontology analysis, categories such as ion transport, response to stimuli, and metabolic process were upregulated. The pathway analysis suggested overexpression of the mitogen-activated protein kinase (MAPK) pathway in CMM patients and to a higher degree in a pathway network. Overexpression of representative members of the MAPK pathway-including MAPK kinase 3 (MEK3), calcium voltage-gated channel auxiliary subunit gamma 2 (CACNG2), and growth arrest and DNA damage-inducible gamma (GADD45G)-was validated with real-time polymerase chain reaction. The upregulation of MEK3 was negatively correlated with the age of the CMM group. In the next step, the authors focused on MEK3, the gene that exhibited the greatest degree of differential expression, and its downstream target protein p38 MAPK. The results revealed upregulation of MEK3, as well as phosphorylated MEK3 and phosphorylated p38 MAPK, in CMM patients. These results provide a "fingerprint" for mechanistic studies of CMM in the future and highlight the importance of MEK3-p38 MAPK activation in CMM.

MicroRNAs as Salivary Markers for Periodontal Diseases: A New Diagnostic Approach?

The aim of this review is to discuss current findings regarding the roles of miRNAs in periodontal diseases and the potential use of saliva as a diagnostic medium for corresponding miRNA investigations. For periodontal disease, investigations have been restricted to tissue samples and five miRNAs, that is, miR-142-3p, miR-146a, miR-155, miR-203, and miR-223, were repeatedly validated in vivo and in vitro by different validation methods. Particularly noticeable are the small sample sizes, different internal controls, and different case definitions of periodontitis in in vivo studies. Beside of that, the validated miRNAs are associated with inflammation and therefore with various diseases. Furthermore, several studies successfully explored the use of salivary miRNA species for the diagnosis of oral cancer. Different cancer types were investigated and heterogeneous methodology was used; moreover, no overlap of results was found. In conclusion, five miRNAs have consistently been reported for periodontitis; however, their disease specificity, detectability, and expression in saliva and their importance as noninvasive markers are questionable. In principle, a salivary miRNA diagnostic method seems feasible. However, standardized criteria and protocols for preanalytics, measurements, and analysis should be established to obtain comparable results across different studies.

New Concepts in Cancer Biomarkers: Circulating miRNAs in Liquid Biopsies

The effective and efficient management of cancer patients relies upon early diagnosis and/or the monitoring of treatment, something that is often difficult to achieve using standard tissue biopsy techniques. Biological fluids such as blood hold great possibilities as a source of non-invasive cancer biomarkers that can act as surrogate markers to biopsy-based sampling. The non-invasive nature of these “liquid biopsies” ultimately means that cancer detection may be earlier and that the ability to monitor disease progression and/or treatment response represents a paradigm shift in the treatment of cancer patients. Below, we review one of the most promising classes of circulating cancer biomarkers: microRNAs (miRNAs). In particular, we will consider their history, the controversy surrounding their origin and biology, and, most importantly, the hurdles that remain to be overcome if they are really to become part of future clinical practice.

Salivary epigenetic biomarkers in head and neck squamous cell carcinomas

The early detection of head and neck squamous cell carcinoma (HNSCC) continues to be a challenge to the clinician. Saliva as a diagnostic medium carries significant advantages including its close proximity to the region of interest, ease of collection and noninvasive nature. While the identification of biomarkers continues to carry significant diagnostic and prognostic utility in HNSCC, epigenetic alterations present a novel opportunity to serve this purpose. With the developments of novel and innovative technologies, epigenetic alterations are now emerging as attractive candidates in HNSCC. As such, this review will focus on two commonly aberrant epigenetic alterations: DNA methylation and microRNA expression in HNSCC and their potential clinical utility. Identification and validation of these salivary epigenetic biomarkers would not only enable early diagnosis but will also facilitate in the clinical management.

Recent advances in salivary cancer diagnostics enabled by biosensors and bioelectronics

There is a high demand for a non-invasive, rapid, and highly accurate tool for disease diagnostics. Recently, saliva based diagnostics for the detection of specific biomarkers has drawn significant attention since the sample extraction is simple, cost-effective, and precise. Compared to blood, saliva contains a similar variety of DNA, RNA, proteins, metabolites, and microbiota that can be compiled into a multiplex of cancer detection markers. The salivary diagnostic method holds great potential for early-stage cancer diagnostics without any complicated and expensive procedures. Here, we review various cancer biomarkers in saliva and compare the biomarkers efficacy with traditional diagnostics and state-of-the-art bioelectronics. We summarize biomarkers in four major groups: genomics, transcriptomics, proteomics, and metabolomics/microbiota. Representative bioelectronic systems for each group are summarized based on various stages of a cancer. Systematic study of oxidative stress establishes the relationship between macromolecules and cancer biomarkers in saliva. We also introduce the most recent examples of salivary diagnostic electronics based on nanotechnologies that can offer rapid, yet highly accurate detection of biomarkers. A concluding section highlights areas of opportunity in the further development and applications of these technologies.

MiRNA-323-5p Promotes U373 Cell Apoptosis by Reducing IGF-1R

BACKGROUND MicroRNA regulates mammalian cell growth in terms of its proliferation and apoptosis by controlling the expression of target genes. MiRNA-323-5p plays an important role in regulating cell growth and death within various types of cells. The function of miRNA-323-5p and its possible molecular mechanism in human cerebral glioma U373 cells remains to be further confirmed. The aim of this study was to investigate the regulation function of miRNA-323-5p in human glioma U373 cell growth, proliferation, and apoptosis. MATERIAL AND METHODS We used human cerebral glioma U373 cells as the cell model; utilized liposome technology (transfected by Lipofectamine2000) in human cerebral glioma U373 cells to over-express miRNA-323-5p (microRNA used as control group); and selected MTT assay and flow cytometry to detect cell growth, proliferation, and apoptosis. We used RT-PCR and Western blotting techniques to study the expression levels of target insulin-like growth factor 1 (IGF-1) receptor protein in U373 cells transfected with miRNA-323-5p. We used liposome transfection techniques in human cerebral glioma U373 cells to over-express or processed knockdown of IGF-1R by siRNA, and then transferred with miRNA-323-5p, thereby investigating the treated human cerebral glioma U373 cells apoptosis situations. RESULTS The over-expression of miRNA-323-5p inhibited the growth and proliferation of human cerebral glioma U373 cells and promoted its apoptosis. The over-expression of miRNA-323-5p also reduced the IGF-1R level. After processing the knockdown of IGF-1R and then transfection with miRNA-323-5p, U373 cells had enhanced apoptosis. The over-expression of IGF-1R inhibited the cells apoptosis induced by miRNA-323-5p. CONCLUSIONS MiRNA-323-5p inhibited human cerebral glioma U373 cell proliferation and promoted its apoptosis by reducing IGF-1R.

MicroRNA-31 upregulation predicts increased risk of progression of oral potentially malignant disorder

OBJECTIVES

MicroRNAs (miRNAs, miRs) have shown diagnostic and prognostic potential for oral cancer but their role in oral potentially malignant disorder (OPMD) has been less investigated. We aimed to assess whether miR-21 and miR-31, two of the most relevant miRNAs in oral cancer, are useful as prognostic factors for OPMD progression.

MATERIALS AND METHODS

miR-21 and miR-31 in 20 saliva samples and 46 tissue samples from patients with OPMD (mean follow-up of 820days) were analyzed by quantitative reverse transcription PCR and in situ hybridization, respectively. The log-rank test, receiver operating characteristic curve, and Kaplan-Meier disease free survival analysis were used to assess the correlation between miRNA levels and OPMD progression.

RESULTS

Significantly increased salivary miR-21 and miR-31 expression (P=0.003 and P<0.001, respectively) was observed in patients with OPMD compared to control individuals. Patients with recurrent OPMD and/or malignant transformation exhibited a further augmented expression of miR-31, but not miR-21, in the epithelium. Furthermore, increased miR-31 expression as well as epithelial dysplasia is an independent risk factor for OPMD progression as demonstrated in Cox-proportional hazard model (HR: 8.43, P<0.05, 95%CI: 1.04 to 68.03).

CONCLUSIONS

Salivary miR-21 and miR-31 are applicable as useful OPMD screening tools. Epithelial dysplasia and miR-31 up-regulation synergistically predict the increased incidence of recurrence and/or malignant transformation in patients with OPMD. Detection of miR-31 expression is an adjuvant method for screening of high-risk OPMD.

MicroRNAs as biomarkers for dental diseases

MicroRNAs (miRNAs) are short, noncoding RNAs that act as key regulators of diverse biological processes by mediating translational repression or mRNA degradation of target genes. Recent studies discovered miRNAs in saliva, and these miRNAs are promising candidates for use as biomarkers of dental diseases. In this review, the results of miRNA studies in the dental field are presented, and a brief overview of the current progress, limitations, and perspectives regarding miRNA biomarkers for dental diseases is given.

The increase of oncogenic miRNA expression in tongue carcinogenesis of a mouse model

OBJECTIVES

This study investigated the oncogenic miRNA level in the tissue and biofluids in the Nitroquinoline 1-Oxide (4NQO)-induced mouse tongue carcinogenesis model for potential diagnostic or therapeutic application.

MATERIALS AND METHODS

The histological examination, immunohistochemistry, in situ hybridization, quantitative PCR analysis and bioinformatic algorithms were performed to unravel the signaling activation and miRNA expression in female murine samples.

RESULTS

The increase of miR-21 and miR-31 staining, and EGFR activation paralleled the severity of 4NQO-induced epithelial pathogenesis in tongue epithelium. A progressive increase of miR-21, miR-31 and miR-146a in both saliva and plasma samples was also noted. miR-31 was the earliest emerging miRNA in the saliva. The increase of plasma miR-146a, miR-184 and miR-372 was detectable early in the induction, and it was particularly eminent at the most advanced lesion state. The combined analysis of the multiple oncogenic miRNAs in the plasma signified a potent discriminative capacity between normal and pathological states. As the blockage of EGFR or AKT activation drastically reverted the miR-21, miR-31 and miR-146a expression induced by 4NQO in human oral carcinoma cell lines, the results implicated a mechanistic linkage of the oncogenic miRNAs' induction through EGFR/AKT activation.

CONCLUSIONS

In this study, we show the dysregulation of oncogenic miRNAs in murine tongue tumorigenesis, which simulates human counterparts. Increased multiple miRNAs in the biofluids may be valuable non-invasive markers in detecting oral carcinogenesis at an early stage. This animal model may also be useful for developing liquid biopsies and prevention strategies against oral carcinoma by abrogating EGFR or oncogenic miRNAs.

Diagnostic profiling of salivary exosomal microRNAs in oral lichen planus patients

OBJECTIVE

Oral lichen planus is a chronic inflammatory oral mucosal disease whose exact cause is unclear and which requires efficient diagnostic and therapeutic strategies. Identification of disease-specific biomarkers in saliva is an easy, quick, and non-invasive approach for molecular diagnosis. This study was designed to examine salivary exosomal microRNAs (miRNAs) that could be candidates for diagnosing and elucidating the pathogenesis of oral lichen planus.

SUBJECTS AND METHODS

We compared miRNA profiles of salivary exosomes of patients with oral lichen planus with those of healthy controls. Saliva samples from 16 patients with oral lichen planus and eight healthy controls were divided into two sets and examined using miRNA microarray analysis and TaqMan quantitative PCR.

RESULTS

The three miRNAs identified (miR-4484, miR-1246, and miR-1290) were further validated. Of these, miR-4484 was significantly upregulated in the salivary exosomes of patients with oral lichen planus.

CONCLUSIONS

This study thus identifies a potential miRNA biomarker for oral lichen planus and provides insight into the functions of miRNAs in the pathogenesis of oral inflammatory diseases.

MicroRNAs as Important Players and Biomarkers in Oral Carcinogenesis

Oral cancer, represented mainly by oral squamous cell carcinoma (OSCC), is the eighth most common type of human cancer worldwide. The number of new OSCC cases is increasing worldwide, especially in the low-income countries, and the prognosis remains poor in spite of recent advances in the diagnostic and therapeutic modalities. MicroRNAs (miRNAs), 18–25 nucleotides long noncoding RNA molecules, have recently gained significant attention as potential regulators and biomarkers for carcinogenesis. Recent data show that several miRNAs are deregulated in OSCC, and they have either a tumor suppressive or an oncogenic role in oral carcinogenesis. This review summarizes current knowledge on the role of miRNAs as tumor promotors or tumor suppressors in OSCC development and discusses their potential value as diagnostic and prognostic markers in OSCC.

Increased number of circulating exosomes and their microRNA cargos are potential novel biomarkers in alcoholic hepatitis

Background

It has been well documented that alcohol and its metabolites induce injury and inflammation in the liver. However, there is no potential biomarker to monitor the extent of liver injury in alcoholic hepatitis patients. MicroRNAs (miRNAs) are a class of non-coding RNAs that are involved in various physiologic and pathologic processes. In the circulation, a great proportion of miRNAs is associated with extracellular vesicles (EVs)/exosomes. Here, we hypothesized that the exosome-associated miRNAs can be used as potential biomarkers in alcoholic hepatitis (AH).

Methods

Exosomes were isolated from sera of alcohol-fed mice or pair-fed mice, and plasma of alcoholic hepatitis patients or healthy controls by ExoQuick. The exosomes were characterized by transmission electron microscopy and Western blot and enumerated with a Nanoparticle Tracking Analysis system. Firefly™ microRNA Assay was performed on miRNA extracted from mice sera. TaqMan microRNA assay was used to identify differentially expressed miRNAs in plasma of cohort of patients with AH versus controls followed by construction of receiver operating characteristic (ROC) curves to determine the sensitivity and specificity of the candidates.

Results

The total number of circulating EVs was significantly increased in mice after alcohol feeding. Those EVs mainly consisted of exosomes, the smaller size vesicle subpopulation of EVs. By performing microarray screening on exosomes, we found nine inflammatory miRNAs which were deregulated in sera of chronic alcohol-fed mice compared to controls including upregulated miRNAs: miRNA-192, miRNA-122, miRNA-30a, miRNA-744, miRNA-1246, miRNA 30b and miRNA-130a. The ROC analyses indicated excellent diagnostic value of miRNA-192, miRNA-122, and miRNA-30a to identify alcohol-induced liver injury. We further validated findings from our animal model in human samples. Consistent with the animal model, total number of EVs, mostly exosomes, was significantly increased in human subjects with AH. Both miRNA-192 and miRNA-30a were significantly increased in the circulation of subjects with AH. miRNA-192 showed promising value for the diagnosis of AH.

Conclusion

Elevated level of EVs/exosomes and exosome-associated miRNA signature could serve as potential diagnostic markers for AH. In addition to the biomarker diagnostic capabilities, these findings may facilitate development of novel strategies for diagnostics, monitoring, and therapeutics of AH.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0623-9) contains supplementary material, which is available to authorized users.

Salivary MicroRNA in Pancreatic Cancer Patients

Background

Pancreatic cancer is the fourth leading cause of cancer death in Western countries, with the lowest 1-year survival rate among commonly diagnosed cancers. Reliable biomarkers for pancreatic cancer diagnosis are lacking and are urgently needed to allow for curative surgery. As microRNA (miRNA) recently emerged as candidate biomarkers for this disease, we explored in the present pilot study the differences in salivary microRNA profiles between patients with pancreatic tumors that are not eligible for surgery, precancerous lesions, inflammatory disease or cancer-free patients as a potential early diagnostic tool.

Methods

Whole saliva samples from patients with pancreatic cancer (n = 7), pancreatitis (n = 4), IPMN (n = 2), or healthy controls (n = 4) were obtained during endoscopic examination. After total RNA isolation, expression of 94 candidate miRNAs was screened by q(RT)PCR using Biomark Fluidgm. Human-derived pancreatic cancer cells were xenografted in athymic mice as an experimental model of pancreatic cancer.

Results

We identified hsa-miR-21, hsa-miR-23a, hsa-miR-23b and miR-29c as being significantly upregulated in saliva of pancreatic cancer patients compared to control, showing sensitivities of 71.4%, 85.7%, 85,7% and 57%, respectively and excellent specificity (100%). Interestingly, hsa-miR-23a and hsa-miR23b are overexpressed in the saliva of patients with pancreatic cancer precursor lesions. We found that hsa-miR-210 and let-7c are overexpressed in the saliva of patients with pancreatitis as compared to the control group, with sensitivity of 100% and 75%, and specificity of 100% and 80%, respectively. Last hsa-miR-216 was upregulated in cancer patients as compared to patients diagnosed with pancreatitis, with sensitivity of 50% and specificity of 100%. In experimental models of PDAC, salivary microRNA detection precedes systemic detection of cancer cells markers.

Conclusions

Our novel findings indicate that salivary miRNA are discriminatory in pancreatic cancer patients that are not eligible for surgery. In addition, we demonstrate in experimental models that salivary miRNA detection precedes systemic detection of cancer cells markers. This study stems for the use of salivary miRNA as biomarker for the early diagnosis of patients with unresectable pancreatic cancer.

Salivary microRNAs in oral cancer

OBJECTIVE

This study investigated the use of three salivary microRNAs (miRNA-21, miRNA-184, and miRNA-145) as possible markers for malignant transformation in oral mucosal lesions.

MATERIALS AND METHODS

Salivary whole unstimulated samples were collected from a study group of 100 subjects, consisting of 20 clinically healthy controls, 40 patients with oral potentially malignant disorders (PMDs) [20 with dysplastic lesions and 20 without dysplasia], 20 with biopsy-confirmed oral squamous cell carcinoma (OSCC), and 20 with recurrent aphthous stomatitis (RAS) as disease controls. Total RNA was isolated and purified from saliva samples using the microRNA Isolation Kit (Qiagen, UL). miRNA expression analysis was performed using qRT-PCR (Applied Biosystems).

RESULTS

There was a highly significant increase in salivary miRNA-21 and miRNA-184 in OSCC and PMD (with and without dysplasia) when compared to healthy and disease controls (P < 0.001). Conversely, miRNA-145 levels showed a highly significant decrease in OSCC and PMD overall (P < 0.001). RAS cases showed no significant difference from normal controls in any measured miRNA (P > 0.05). The only microRNA to discriminate between OSCC and PMD with dysplasia was miRNA-184. When receiver operating characteristic curves were designed for the three miRNAs, cutoff points delineating the occurrence of malignant change were a fourfold increase in miRNA-21 with specificity 65% and sensitivity 65%, a 0.6 decrease in miRNA-145, with specificity 70% and sensitivity 60%, and a threefold increase of miRNA-184, with specificity 75% and sensitivity 80%. Calculating the area under the curve revealed that miRNA-184 was the only one among the studied miRNAs that provided good diagnostic value.

CONCLUSION

Salivary determination of the miRNAs tested might furnish a noninvasive, rapid adjunctive aid for revealing malignant transformation in oral mucosal lesions, particularly miRNA-184.

Non-coding RNAs in saliva: emerging biomarkers for molecular diagnostics

Saliva is a complex body fluid that comprises secretions from the major and minor salivary glands, which are extensively supplied by blood. Therefore, molecules such as proteins, DNA, RNA, etc., present in plasma could be also present in saliva. Many studies have reported that saliva body fluid can be useful for discriminating several oral diseases, but also systemic diseases including cancer. Most of these studies revealed messenger RNA (mRNA) and proteomic biomarker signatures rather than specific non-coding RNA (ncRNA) profiles. NcRNAs are emerging as new regulators of diverse biological functions, playing an important role in oncogenesis and tumor progression. Indeed, the small size of these molecules makes them very stable in different body fluids and not as susceptible as mRNAs to degradation by ribonucleases (RNases). Therefore, the development of a non-invasive salivary test, based on ncRNAs profiles, could have a significant applicability to clinical practice, not only by reducing the cost of the health system, but also by benefitting the patient. Here, we summarize the current status and clinical implications of the ncRNAs present in human saliva as a source of biological information.

Salivary extracellular noncoding RNA: emerging biomarkers for molecular diagnostics

Saliva is a complex body fluid that comprises secretions from the major and minor salivary glands, nourished by body's vasculature. Although many circulatory molecules (DNA, RNA, and proteins) can also be present in saliva, saliva harbors unique molecular constituents that can be discriminatory for oral and systemic disease screening and detection. Many studies have reported that salivary constituents can discriminate oral diseases (oral cancer and Sjögren's syndrome) and also systemic diseases (lung cancer, breast cancer, pancreatic cancer, and ovarian cancer). Noncoding RNAs (ncRNAs) are emerging new regulators of diverse biological functions, playing important roles in oncogenesis and tumor progression. Indeed, the short size of these molecules makes them stable in different body fluids such as urine, blood, and saliva, being not as susceptible as mRNAs to degradation by RNases. Here, the current status and clinical implications of the ncRNAs present in human saliva are reviewed for translational applications and basic biological research. The development of noninvasive salivary test (based on ncRNAs profiles) for disease detection could have effective applications into the clinical context with a translational significance as emerging molecular biomarkers for non-invasively disease detection, not only by reducing the cost to the health care system but also by benefitting patients.

Diagnostic Relevance of microRNAs in Other Body Fluids Including Urine, Feces, and Saliva

Beside blood-borne circulating miRNAs, miRNAs have been identified in other body fluid and excrements including stool, bile, saliva, and urine. Given the direct link of these body fluids to certain organs, their analysis for potential diagnostic miRNA markers is plausible. Several independent findings underline the potential utility of stool-derived miRNAs in the diagnosis of colorectal and pancreatic cancer. Given the difficulties in the diagnosis of cholangiocellular cancer, biliary miRNAs might be envisaged as useful markers. Several miRNAs have been identified in the saliva that could be associated with diseases, including tumors of the oral cavity. The urinary pool of miRNAs could be exploited for the diagnosis of urinary tract diseases and some appear to enable early diagnosis. In this chapter, we present findings supporting the potential diagnostic utility of fecal, biliary, salivary, and urinary miRNAs focusing mostly on tumors.

Cell-free microRNAs as cancer biomarkers: the odyssey of miRNAs through body fluids

Cell-free microRNAs (cfmiRNAs), also known as extracellular or secretory microRNAs, are an emerging class of miRNAs that are released or secreted by cells. These miRNAs are transferred through various body fluids. A growing body of research has recently revealed that cancer cells also secrete their distinctive cfmiRNAs to the extracellular environment highlighting the contribution of cfmiRNAs to cancer progression. CfmiRNAs show high stability in the body fluids. Three pathways have been proposed for their entry into the body fluids: passive release from broken, injured and dead cells; active secretion through microvesicles; and active secretion via microvesicle-free protein-dependent route. Active pathways seem to play leading roles in the delivery of miRNAs. Detection of cfmiRNAs is of particular relevance to their translation into the clinic. Much effort has been devoted to the development of highly sensitive and efficient approaches for detection purposes. Nevertheless, some barriers such as finding a unique internal control for all cancer types remain to be bypassed. This review aims to provide an insight into the promises represented by cfmiRNAs as cancer biomarkers and describes advances made in the identification of numerous types of extracellular miRNAs that have potential for use in the diagnosis of a variety of cancers.