Human salivary microRNAs in Cancer

Sample-to-answer salivary miRNA testing: New frontiers in point-of-care diagnostic technologies

MicroRNA (miRNA), crucial non-coding RNAs, have emerged as key biomarkers in molecular diagnostics, prognosis, and personalized medicine due to their significant role in gene expression regulation. Salivary miRNA, in particular, stands out for its non-invasive collection method and ease of accessibility, offering promising avenues for the development of point-of-care diagnostics for a spectrum of diseases, including cancer, neurodegenerative disorders, and infectious diseases. Such development promises rapid and precise diagnosis, enabling timely treatment. Despite significant advancements in salivary miRNA-based testing, challenges persist in the quantification, multiplexing, sensitivity, and specificity, particularly for miRNA at low concentrations in complex biological mixtures. This work delves into these challenges, focusing on the development and application of salivary miRNA tests for point-of-care use. We explore the biogenesis of salivary miRNA and analyze their quantitative expression and their disease relevance in cancer, infection, and neurodegenerative disorders. We also examined recent progress in miRNA extraction, amplification, and multiplexed detection methods. This study offers a comprehensive view of the development of salivary miRNA-based point-of-care testing (POCT). Its successful advancement could revolutionize the early detection, monitoring, and management of various conditions, enhancing healthcare outcomes. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > Diagnostic Nanodevices.

Assessment of salivary miRNA, clinical, and demographic characterization in colorectal cancer diagnosis

AIM

Colorectal cancer (CRC), as the third most frequent malignancy in the world, is the fourth major cause of cancer-related mortality. Its early detection contributes significantly to a reduction in mortality. The objective of this case-control research was to analyze the salivary expression of microRNA-29a (miR-29a) and microRNA-92a (miR-92a), and also to consider demographic, clinical, and nutritional habits for differentiation between CRC patients and healthy controls, especially in the early stages.

METHOD

A standard checklist was used to obtain the demographic information, clinical features, and dietary habits of the case and control groups. Samplings of whole unstimulated saliva samples were obtained from 33 healthy persons and 42 CRC patients. Through real-time PCR, statistical analyses, and machine learning analyses, miR-29a and miR-92a salivary expression levels were evaluated.

RESULTS

The mean salivary expression of miR-92a and miR-29a in CRC patients was significantly higher than in healthy controls (p < 0.001). The area under the receiver operating characteristic curve for miR-92a and miR-29a salivary biomarkers was 0.947 and 0.978, respectively. The sensitivity and specificity values for miR-92a were 95.24 % and 84.85 %, respectively, whereas sensitivity and specificity for miR-29a were equal to 95.20 % and 87.88 %, respectively. Multiple logistic regressions considering demographics, clinical features, and nutritional habits led to values of 95.35 % and 96.88 % as sensitivity and specificity, respectively, and machine learning analysis led to values of 88.89 % and 86.67 % as sensitivity and specificity, respectively.

CONCLUSION

CRC could be accurately diagnosed based on miR-92a and miR-29a levels in saliva. Statistical analysis and machine learning might develop cost-effective models for the distinction of CRC using a noninvasive technique.

A novel saliva-based miRNA profile to diagnose and predict oral cancer

Oral cancer (OC) is the most common form of head and neck cancer. Despite the high incidence and unfavourable patient outcomes, currently, there are no biomarkers for the early detection of OC. This study aims to discover, develop, and validate a novel saliva-based microRNA signature for early diagnosis and prediction of OC risk in oral potentially malignant disorders (OPMD). The Cancer Genome Atlas (TCGA) miRNA sequencing data and small RNA sequencing data of saliva samples were used to discover differentially expressed miRNAs. Identified miRNAs were validated in saliva samples of OC (n = 50), OPMD (n = 52), and controls (n = 60) using quantitative real-time PCR. Eight differentially expressed miRNAs (miR-7-5p, miR-10b-5p, miR-182-5p, miR-215-5p, miR-431-5p, miR-486-3p, miR-3614-5p, and miR-4707-3p) were identified in the discovery phase and were validated. The efficiency of our eight-miRNA signature to discriminate OC and controls was: area under curve (AUC): 0.954, sensitivity: 86%, specificity: 90%, positive predictive value (PPV): 87.8% and negative predictive value (NPV): 88.5% whereas between OC and OPMD was: AUC: 0.911, sensitivity: 90%, specificity: 82.7%, PPV: 74.2% and NPV: 89.6%. We have developed a risk probability score to predict the presence or risk of OC in OPMD patients. We established a salivary miRNA signature that can aid in diagnosing and predicting OC, revolutionising the management of patients with OPMD. Together, our results shed new light on the management of OC by salivary miRNAs to the clinical utility of using miRNAs derived from saliva samples.

Salivary biomarkers: novel noninvasive tools to diagnose chronic inflammation

Several chronic disorders including type 2 diabetes (T2D), obesity, heart disease and cancer are preceded by a state of chronic low-grade inflammation. Biomarkers for the early assessment of chronic disorders encompass acute phase proteins (APP), cytokines and chemokines, pro-inflammatory enzymes, lipids and oxidative stress mediators. These substances enter saliva through the blood flow and, in some cases, there is a close relation between their salivary and serum concentration. Saliva can be easily collected and stored with non-invasive and cost-saving procedures, and it is emerging the concept to use it for the detection of inflammatory biomarkers. To this purpose, the present review aims to discuss the advantages and challenges of using standard and cutting-edge techniques to discover salivary biomarkers which may be used in diagnosis/therapy of several chronic diseases with inflammatory consequences with the pursuit to possibly replace conventional paths with detectable soluble mediators in saliva. Specifically, the review describes the procedures used for saliva collection, the standard approaches for the measurement of salivary biomarkers and the novel methodological strategies such as biosensors to improve the quality of care for chronically affected patients.

Ultrasensitive Detection of MicroRNA in Human Saliva via Rolling Circle Amplification Using a DNA-Decorated Graphene Oxide Sensor

MicroRNAs (miRNAs) are a family of conserved small noncoding RNAs whose expression is associated with many diseases, including cancer. Salivary miRNAs are gaining popularity as noninvasive diagnostic biomarkers for cancer and other systemic disorders, but their use is limited by their low abundance and complicated detection procedure. Herein, we present a novel self-assembly approach based on rolling circle amplification (RCA) and graphene oxide (GO) for the ultrasensitive detection of miRNA21 and miRNA16 (miRNA oral cancer biomarkers in human saliva). First, target miRNA hybridizes with the RCA template. In the presence of DNA polymerase, the RCA reaction is induced and sequences matching the template are generated. Then, a nicking enzyme cuts the long ssDNA product into tiny pieces to obtain the amplified products. The DNA-decorated GO sensor was fabricated by preabsorbing the ssDNA fluorescence-labeled probe on the GO surface, resulting in fluorescence quenching. The DNA-decorated GO sensor could detect the amplified product via the self-assembly of dsDNA, leading to the desorption and recovery of the fluorescence-labeled probe. Under optimal conditions, the proposed system exhibited ultrasensitive detection; the detection limits of miRNA16 and miRNA21 were 8.81 and 3.85 fM, respectively. It showed a wide range of detection between 10 fM and 100 pM for miRNA16 and between 10 fM and 1 nM for miRNA16. It demonstrated high selectivity, distinguishing between 1- and 3-mismatch nucleotides in target miRNA. Overall, our proposed DNA-decorated GO sensor can accurately detect the salivary miRNAs and may potentially be used for the diagnosis and screening of early-stage oral cancer.

Circulating Biomarkers for Cancer Detection: Could Salivary microRNAs Be an Opportunity for Ovarian Cancer Diagnostics?

MicroRNAs (miRNAs) are small non-coding RNAs with the crucial regulatory functions of gene expression at post-transcriptional level, detectable in cell and tissue extracts, and body fluids. For their stability in body fluids and accessibility to sampling, circulating miRNAs and changes of their concentration may represent suitable disease biomarkers, with diagnostic and prognostic relevance. A solid literature now describes the profiling of circulating miRNA signatures for several tumor types. Among body fluids, saliva accurately reflects systemic pathophysiological conditions, representing a promising diagnostic resource for the future of low-cost screening procedures for systemic diseases, including cancer. Here, we provide a review of literature about miRNAs as potential disease biomarkers with regard to ovarian cancer (OC), with an excursus about liquid biopsies, and saliva in particular. We also report on salivary miRNAs as biomarkers in oncological conditions other than OC, as well as on OC biomarkers other than miRNAs. While the clinical need for an effective tool for OC screening remains unmet, it would be advisable to combine within a single diagnostic platform, the tools for detecting patterns of both protein and miRNA biomarkers to provide the screening robustness that single molecular species separately were not able to provide so far.

Characteristics of Human and Microbiome RNA Profiles in Saliva

Saliva is a convenient non-invasive source of liquid biopsy to monitor human health and diagnose diseases. In particular, extracellular vesicles (EVs) in saliva can potentially reveal clinically relevant information for systemic health. Recent studies have shown that RNA in saliva EVs could be exploited as biomarkers for disease diagnosis. However, there is no standardized protocol for profiling RNA in saliva EV nor clear guideline on selecting saliva fractions for biomarker analysis. To address these issues, we established a robust protocol for small RNA profiling from fractionated saliva. With this method, we performed comprehensive small RNA sequencing of four saliva fractions, including cell-free saliva (CFS), EV-depleted saliva (EV-D), exosome (EXO), and microvesicle (MV) from ten healthy volunteers. By comparing the expression profiles of total RNA from these fractions, we found that MV was most enriched in microbiome RNA (76.2% of total reads on average), whereas EV-D was notably enriched in human RNA (70.3% of total reads on average). As for human RNA composition, CFS and EV-D were both enriched in snoRNA and tRNA compared with the two EV fractions (EXO and MV, P < 0.05). Interestingly, EXO and MV had highly correlated expression profiles for various noncoding RNAs such as miRNA, tRNA, and yRNA. Our study revealed unique characteristics of circulating RNAs in various saliva fractions, which provides a guideline on preparing saliva samples to study specific RNA biomarkers of interest.

Salivary miR-21 is a potential biomarker for canine mast cell tumors

MicroRNAs (miRNAs) are a class of noncoding RNA molecules playing a crucial role in tumor modulation targeting mRNA. This study aimed to validate the diagnostic potential of a panel of 3 miRNAs previously identified in canine mast cell tumors (MCTs), miR-21, miR-379, and miR-885, as markers of lymph node involvement in terms of histological absence (nonmetastatic: HN0; premetastatic: HN1) and presence (early-metastatic: HN2; overt-metastatic: HN3) of metastasis, in the saliva of mast cell tumor (MCT)-affected dogs by quantitative polymerase chain reaction (PCR). Forty-seven saliva samples were analyzed: 36 from MCT-affected dogs (12 subcutaneous [3 HN0-1 and 9 HN2-3] and 24 cutaneous [9 HN0-1 and 15 HN2-3-MCT]) and 11 from healthy dogs. MCT-group effects were investigated using analysis of variance (ANOVA). The origin of the tumor affected the expression of salivary miR-21 (P = .011) with an increase in cases with subcutaneous MCTs compared with the healthy group (P = .0005) and those with cutaneous MCTs (P = .004). Salivary miR-21 was higher in the HN2-3 class compared with the healthy group (P = .004). Salivary miR-885 was not affected by the presence of MCT, while miR-379 was not detected in saliva. The diagnostic potential of salivary miR-21 in discriminating MCT-affected dogs from the healthy group (AUC = 0.8917), cutaneous from subcutaneous (AUC = 0.8111), and subcutaneous HN0-1 (AUC = 0.7250) and HN2-3 (AUC = 0.9750) classes from healthy samples was demonstrated by receiver operating characteristic curve analysis. Overall, salivary miR-21 was identified as a promising tool, representing a novel approach to detecting MCT-associated epigenetic alterations in a minimally invasive manner.

The Potential of MicroRNAs as Clinical Biomarkers to Aid Ovarian Cancer Diagnosis and Treatment

Ovarian cancer is a commonly diagnosed malignancy in women. When diagnosed at an early stage, survival outcomes are favourable for the vast majority, with up to 90% of ovarian cancer patients being free of disease at 5 years follow-up. Unfortunately, ovarian cancer is typically diagnosed at an advanced stage due to the majority of patients remaining asymptomatic until the cancer has metastasised, resulting in poor outcomes for the majority. While the molecular era has facilitated the subclassification of the disease into distinct clinical subtypes, ovarian cancer remains managed and treated as a single disease entity. MicroRNAs (miRNAs) are small (19-25 nucleotides), endogenous molecules which are integral to regulating gene expression. Aberrant miRNA expression profiles have been described in several cancers, and have been implicated to be useful biomarkers which may aid cancer diagnostics and treatment. Several preliminary studies have identified candidate tumour suppressor and oncogenic miRNAs which may be involved in the development and progression of ovarian cancer, highlighting their candidacy as oncological biomarkers; understanding the mechanisms by which these miRNAs regulate the key processes involved in oncogenesis can improve our overall understanding of cancer development and identify novel biomarkers and therapeutic targets. This review highlights the potential role of miRNAs which may be utilised to aid diagnosis, estimate prognosis and enhance therapeutic strategies in the management of primary ovarian cancer.

MicroRNAs’ Crucial Role in Salivary Gland Cancers’ Onset and Prognosis

Simple Summary

Salivary gland cancers are incredibly heterogeneous, both in the physical onset and in the aggressiveness. Setting up a novel diagnostic and prognostic detection method based on the noninvasive microRNAs’ profiling might represent a goal for the clinical management of those particular malignancies, saving precious time for the patients.

Abstract

Salivary gland cancer (SGC) is an uncommon and heterogeneous disease that accounts for around 8.5% of all head and neck cancers. MicroRNAs (miRNAs) consist of a class of highly conserved, short, single-stranded segments (18–25 nucleotides) of noncoding RNA that represent key gene-transcription regulators in physiological and pathological human conditions. However, their role in SGC development and progression is not completely clear. This review aims to compile and summarize the recent findings on the topic, focusing on the prognostic and diagnostic value of the major modulated and validated microRNAs in SGC. Their differential expression could possibly aid the clinician in delivering an early diagnosis, therapeutic strategy and precision medicine.

Salivary Exosomal MicroRNA-486-5p and MicroRNA-10b-5p in Oral and Oropharyngeal Squamous Cell Carcinoma

Background and Objectives: The research aimed at evaluating the capacity of salivary exosomal miR-10b-5p and miR-486-5p for oral and oropharyngeal cancer detection. Materials and Methods: The saliva samples were harvested from histopathological diagnosed oral and oropharyngeal squamous cell carcinoma patients and healthy volunteer subjects. The exosomes were isolated by differential ultracentrifugation and quantified by Nano Track Analysis. The microRNAs were extracted and quantified from salivary exosomes by quantitative Real-Time Polymerase Chain Reaction. Results: This research comprised fifty participants. When compared to healthy controls, salivary exosomal miR-486-5p was elevated and miR-10b-5p was reduced in oral and oropharyngeal squamous cell carcinoma. Moreover, miR-486-5p had a high expression level in stage II of cancer in comparison to the other cancer stages. The cancer samples presented an increased exosome dimension compared to the control samples. Conclusions: Salivary exosomal miR-10b-5p and miR-486-5p have an altered expression in oral and oropharyngeal cancer.

Confounding Factors Impacting microRNA Expression in Human Saliva: Methodological and Biological Considerations

There is growing interest in saliva microRNAs (miRNAs) as non-invasive biomarkers for human disease. Such an approach requires understanding how differences in experimental design affect miRNA expression. Variations in technical methodologies, coupled with inter-individual variability may reduce study reproducibility and generalizability. Another barrier facing salivary miRNA biomarker research is a lack of recognized “control miRNAs”. In one of the largest studies of human salivary miRNA to date (922 healthy individuals), we utilized 1225 saliva samples to quantify variability in miRNA expression resulting from aligner selection (Bowtie1 vs. Bowtie2), saliva collection method (expectorated vs. swabbed), RNA stabilizer (presence vs. absence), and individual biological factors (sex, age, body mass index, exercise, caloric intake). Differential expression analyses revealed that absence of RNA stabilizer introduced the greatest variability, followed by differences in methods of collection and aligner. Biological factors generally affected a smaller number of miRNAs. We also reported coefficients of variations for 643 miRNAs consistently present in saliva, highlighting several salivary miRNAs to serve as reference genes. Thus, the results of this analysis can be used by researchers to optimize parameters of salivary miRNA measurement, exclude miRNAs confounded by numerous biologic factors, and identify appropriate miRNA controls.

Potential utility of miRNAs for liquid biopsy in breast cancer

Breast cancer (BC) remains the most prevalent malignancy due to its incidence rate, recurrence, and metastasis in women. Conventional strategies of cancer detection– mammography and tissue biopsy lack the capacity to detect the complete cancer genomic landscape. Besides, they often give false- positive or negative results. The presence of this and other disadvantages such as invasiveness, high-cost, and side effects necessitates developing new strategies to overcome the BC burden. Liquid biopsy (LB) has been brought to the fore owing to its early detection, screening, prognosis, simplicity of the technique, and efficient monitoring. Remarkably, microRNAs (miRNAs)– gene expression regulators seem to play a major role as biomarkers detected in the samples of LB. Particularly, miR-21 and miR-155 among other possible candidates seem to serve as favorable biomarkers in the diagnosis and prognosis of BC. Hence, this review will assess the potential utility of miRNAs as biomarkers and will highlight certain promising candidates for the LB approach in the diagnosis and management of BC that may optimize the patient outcome.

Salivary biomarkers in breast cancer diagnosis: A systematic review and diagnostic meta-analysis

BACKGROUND

Salivary diagnostics and their utility as a nonaggressive approach for breast cancer diagnosis have been extensively studied in recent years. This meta-analysis assesses the diagnostic value of salivary biomarkers in differentiating between patients with breast cancer and controls.

METHODS

We conducted a meta-analysis and systematic review of studies related to salivary diagnostics published in PubMed, EMBASE, Scopus, Ovid, Science Direct, Web of Science (WOS), and Google Scholar. The articles were chosen utilizing inclusion and exclusion criteria, as well as assessing their quality. Specificity and sensitivity, along with negative and positive likelihood ratios (NLR and PLR) and diagnostic odds ratio (DOR), were calculated based on random- or fixed-effects model. Area under the curve (AUC) and summary receiver-operating characteristic (SROC) were plotted and evaluated, and Fagan's Nomogram was evaluated for clinical utility.

RESULTS

Our systematic review and meta-analysis included 14 papers containing 121 study units with 8639 adult subjects (4149 breast cancer patients and 4490 controls without cancer). The pooled specificity and sensitivity were 0.727 (95% CI: 0.713-0.740) and 0.717 (95% CI: 0.703-0.730), respectively. The pooled NLR and PLR were 0.396 (95% CI: 0.364-0.432) and 2.597 (95% CI: 2.389-2.824), respectively. The pooled DOR was 7.837 (95% CI: 6.624-9.277), with the AUC equal to 0.801. The Fagan's nomogram showed post-test probabilities of 28% and 72% for negative and positive outcomes, respectively. We also conducted subgroup analyses to determine specificity, sensitivity, DOR, PLR, and NLR based on the mean age of patients (≤52 or >52 years old), saliva type (stimulated and unstimulated saliva), biomarker measurement method (mass spectrometry [MS] and non-MS measurement methods), sample size (≤55 or >55), biomarker type (proteomics, metabolomics, transcriptomics and proteomics, and reagent-free biophotonic), and nations.

CONCLUSION

Saliva, as a noninvasive biomarker, has the potential to accurately differentiate breast cancer patients from healthy controls.

Diagnostic and therapeutic biomarkers in colorectal cancer: a review

Colorectal cancer (CRC) is a public health concern and the second most common type of cancer among men and women causing a significant mortality. Biomarkers closely linked to the disease morbidity could holds potential as diagnostic and/or prognostic biomarker for the disease. This review provides an overview of recent advances in the search for colorectal cancer biomarkers through genomics and proteomics according to clinical function and application. Specifically, a number of biomarkers were identified and discussed. Emphasis was placed on their clinical applications relative to the diagnosis and prognosis of CRC. The discovery of more sensitive and specific markers for CRC is an urgent need, and the study of molecular targets is extremely important in this process, as they will allow for a better understanding of colorectal carcinogenesis, identification and validation of potential genetic signatures.

Potential plasma biomarkers: miRNA-29c, miRNA-21, and miRNA-155 in clinical progression of Hepatocellular Carcinoma patients

This study evaluated differences in the clinical appearance of patients with hepatocellular carcinoma (HCC) based on plasma level and regulation of microRNAs (miRNA-29c, miRNA-21, and miRNA-155). The observational-analytical study with a cross-sectional design was conducted on 36 HCC patients and 36 healthy controls. The blood samples were collected from 2 Province Hospitals (Dr. Sardjito Hospital and Prof. Dr. Margono Soekarjo Hospital) for HCC and the Blood Bank Donor of the Indonesian Red Cross for 36 healthy controls. These blood samples were treated as follows: plasma isolation, RNA isolation, cDNA synthesis, quantification by qRT-PCR using a sequence-specific forward primer, and normalization of miRNA using housekeeping-stably miRNA-16. There were only 27 HCC patients with complete clinical variables (neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), platelet count, albumin, C-reactive protein (CRP), and cholinesterase (ChE)) that were able to analyses for regulation miRNAs based on its fold change expression miRNA target. All 27 HCC subjects were follow-up until 3-years of monitoring for their overall survival. The miRNA plasma expression was analyzed by Bio-Rad CFX 96 Manager software to determine the cycle of quantification, followed by the calculation of expression levels using Livak’s methods. Data were analyzed using STATA 11.0, with a significant value of p<0.05. The miRNAs expression of HCC subjects were lower than that healthy control subjects in miRNA-29c (down-regulation 1.83-fold), higher than that healthy control subjects in miRNA 21 and miRNA-155 (up-regulation, 1.74-fold; 1.55-fold) respectively. NLR, CRP, ChE, and platelet count showed a significant difference in miRNA-29c regulation, though neutrophil count showed a significant difference in miRNA-21 and miRNA-155 regulation (p<0.05). Conclusion: Plasma biomarkers: miRNA-21 and miRNA-155 might be potential biomarkers as onco-miR in HCC subjects, while miRNA-29c might act as a tumor suppressor. Significant evidence was identified with clinical progression based on the regulation of miRNAs, which was consistent with miRNA -29c.

Salivary miRNAs as non-invasive biomarkers of hepatocellular carcinoma: a pilot study

BACKGROUND

Improved detection of hepatocellular carcinoma (HCC) is needed, as current detection methods, such as alpha fetoprotein (AFP) and ultrasound, suffer from poor sensitivity. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate many cellular functions and impact cancer development and progression. Notably, miRNAs are detectable in saliva and have shown potential as non-invasive biomarkers for a number of cancers including breast, oral, and lung cancers. Here, we present, to our knowledge, the first report of salivary miRNAs in HCC and compare these findings to patients with cirrhosis, a high-risk cohort for HCC.

METHODS

We performed small RNA sequencing in 20 patients with HCC and 19 with cirrhosis. Eleven patients with HCC had chronic liver disease, and analyses were performed with these samples combined and stratified by the presence of chronic liver disease. P values were adjusted for multiple comparisons using a false discovery rate (FDR) approach and miRNA with FDR P < 0.05 were considered statistically significant. Differential expression of salivary miRNAs was compared to a previously published report of miRNAs in liver tissue of patients with HCC vs cirrhosis. Support vector machines and leave-one-out cross-validation were performed to determine if salivary miRNAs have predictive potential for detecting HCC.

RESULTS

A total of 4,565 precursor and mature miRNAs were detected in saliva and 365 were significantly different between those with HCC compared to cirrhosis (FDR P < 0.05). Interestingly, 283 of these miRNAs were significantly downregulated in patients with HCC. Machine-learning identified a combination of 10 miRNAs and covariates that accurately classified patients with HCC (AUC = 0.87). In addition, we identified three miRNAs that were differentially expressed in HCC saliva samples and in a previously published study of miRNAs in HCC tissue compared to cirrhotic liver tissue.

CONCLUSIONS

This study demonstrates, for the first time, that miRNAs relevant to HCC are detectable in saliva, that salivary miRNA signatures show potential to be highly sensitive and specific non-invasive biomarkers of HCC, and that additional studies utilizing larger cohorts are needed.

Expression of Salivary miRNA 21 in Oral Submucous Fibrosis (OSMF): An Observational Study

Objective:

To observe the expression patterns of salivary mRNA 21 in different stages and grades of OSMF and also in habitual areca nut chewers without OSMF.

Subjects and Methods

The study consisted of a total of 185 samples, where 61 patients had chewing habits (chewing gutkha and other forms of areca nut) and had OSMF (Group 1). 61 patients had chewing habits but did not have OSMF (Group 2), and 63 were normal healthy patients (control group) without any chewing habits (Group 3). Unstimulated saliva samples were collected from patients following the standard operating procedures. miRNA 21 was isolated and purified from saliva samples using the miRNeasy Mini Kit, Qiagen. The primers for miRNA relative quantification analysis were designed using the Primer Express software of Applied Biosystems. Quantification of all the samples was carried out using SYBR chemistry in an Applied Biosystems Real-Time PCR.

Results

There was no statistically significant difference between the demographic characteristics of patients. There was a statistically significant difference between the expressions of miRNA 21 amongst the three groups noted in Kruskal Wallis test. (<0.001*) A post hoc test was perfomed to confirm the statistical difference between patients within all three groups. There was no statistically significant difference noted between the OSMF group and patients with chewing habits group (G1 vs. G2 p: 0.10), but there was a significant difference when compared with normal patients. (G1 vs. G3 p: <0.001*) and (G2 vs. G3 <0.001*)

Conclusion

This study concludes that miRNA 21 is overexpressed in OSMF and chewing habit patients. But the expression levels were not significantly associated with the severity of the disease process. A long term and large scale studies are required to assess its application as a diagnostic profibrotic marker in OSMF.

Salivary exosomal microRNAs as biomarkers for head and neck cancer detection-a literature review

Background

MicroRNAs (miRs) are small, non-coding mRNA molecules which regulate cellular processes in tumorigenesis. miRs were discovered in extracellular environment and biological fluids, carrying marks of head and neck squamous cell carcinoma (HNSCC). They were also identified in abundance in salivary exosomes, in which they are protected by exosome lipid barrier against enzymatic injuries and therefore, the accuracy of exosomal miR-based cancer detection increase. This systematic review aimed to reveal and inventorize the most reliable exosomal miRNAs in saliva samples which can be used as novel biomarkers for early detection of HNSCC.

Materials and methods

A systematic literature search, according to PRISMA guideline, was performed on Pubmed and Google Academic libraries, based on specific keywords. Original articles published between 2010 and 2021 were selected. The quality of each paper was assessed using the Quality Evaluation Scoring Tool.

Results

At the end of selection process, five studies met the inclusion criteria. These studies analyzed twelve salivary exosomal miRs, presenting different methods of exosome and miR identification for HNSCC detection. A comprehensive explanation of the miR pathways of action was drawn and illustrated in this review.

Conclusion

Exosomal miRs are promising biomarkers for oral cavity and oropharyngeal cancer detection. miR-10b-5p, miR-486-5p, miR-24-3p and miR-200a stand as the most useful ones in saliva sample examination.

Saliva 1,5-anhydroglucitol is associated with early-phase insulin secretion in Chinese patients with type 2 diabetes

INTRODUCTION

Saliva collection is a non-invasive test and is convenient. 1,5-anhydroglucitol (1,5-AG) is a new indicator reflecting short-term blood glucose levels. This study aimed to explore the relationship between saliva 1,5-AG and insulin secretion function and insulin sensitivity.

RESEARCH DESIGN AND METHODS

Adult patients with type 2 diabetes who were hospitalized were enrolled. Based on blood glucose and C-peptide, homeostasis model assessment 2 for β cell secretion function, C-peptidogenic index (CGI), △2-hour C-peptide (2hCP)/△2-hour postprandial glucose (2hPG), ratio of 0-30 min area under the curve for C-peptide and area under the curve for glucose (AUC_CP30/AUC_PG30), and AUC_2hCP/AUC_2hPG were calculated to evaluate insulin secretion function, while indicators such as homeostasis model assessment 2 for insulin resistance were used to assess insulin sensitivity.

RESULTS

We included 284 subjects (178 men and 106 women) with type 2 diabetes aged 20-70 years. The saliva 1,5-AG level was 0.133 (0.089-0.204) µg/mL. Spearman's correlation analysis revealed a significantly negative correlation between saliva 1,5-AG and 0, 30, and 120 min blood glucose, glycated hemoglobin A_1c, and glycated albumin (all p<0.05), and a significantly positive association between saliva 1,5-AG and CGI (r=0.171, p=0.004) and AUC _CP30 /AUC _PG30 (r=0.174, p=0.003). The above correlations still existed after adjusting for age, sex, body mass index, and diabetes duration. In multiple linear regression, saliva 1,5-AG was an independent factor of CGI (standardized β=0.135, p=0.015) and AUC _CP30 /AUC _PG30 (standardized β=0.110, p=0.020).

CONCLUSIONS

Saliva 1,5-AG was related to CGI and AUC_CP30/AUC_PG30 in patients with type 2 diabetes.

TRIAL REGISTRATION NUMBER

ChiCTR-SOC-17011356.

MiR-21 in the Cancers of the Digestive System and Its Potential Role as a Diagnostic, Predictive, and Therapeutic Biomarker

MicroRNAs (miRNAs) are small non-coding RNAs. They can regulate the expression of their target genes, and thus, their dysregulation significantly contributes to the development of cancer. Growing evidence suggests that miRNAs could be used as cancer biomarkers. As an oncogenic miRNA, the roles of miR-21 as a diagnostic and prognostic biomarker, and its therapeutic applications have been extensively studied. In this review, the roles of miR-21 are first demonstrated via its different molecular networks. Then, a comprehensive review on the potential targets and the current applications as a diagnostic and prognostic cancer biomarker and the therapeutic roles of miR-21 in six different cancers in the digestive system is provided. Lastly, a brief discussion on the challenges for the use of miR-21 as a therapeutic tool for these cancers is added.

High-Sensitivity Dual-Probe Detection of Urinary miR-141 in Cancer Patients via a Modified Screen-Printed Carbon Electrode-Based Electrochemical Biosensor

The screening and diagnosis of cancer are hallmarks of medicine in the aging population. Recently, microRNAs have shown potential for use as biomarkers, which could advance the field of diagnostics. The presence of miRNA-141 in the serum has been well described in several malignancies. However, the invasive approach used for sampling represents the major limitation for its practical application and, hence, its notable absence as a method for screening the general population. In light of this, we aimed to develop a high-sensitivity microRNA (miR) biosensor for application in the diagnosis of all miR-141-associated cancers, such as colorectal cancer (CRC) and breast cancer (BC). The novelty lies in our dual-probe design, which is reliant on the hybridization of the fluorescein isothiocyanate (FITC) targeting probe onto an existing sample of urinary miR-141 in the first step, followed by complementary binding with a biotinylated probe that has been coated on a modified screen-printed carbon electrode (SPCE). The hybridization of the probe and sensor produces signals via the catalytic reduction of H₂O₂ at HRP-modified SPCEs in the presence of H₂O, which was measured by either cyclic voltammetry or chronoamperometry (CA) currents. In our study, the detection and expression of miR-141 in a cohort of colorectal cancer (n = 6) and breast cancer (n = 4) samples showed that its levels were significantly higher than in a healthy cohort (n = 9) (p < 0.004). Moreover, our miR sensor demonstrated high stability, reliability, and sensitivity (p < 0.0001). This work hopefully provides new information for the detection and monitoring of de novo and existing cancers.

The Salivary miRNome: A Promising Biomarker of Disease

MicroRNAs (miRNAs) are non-coding RNAs ranging from 18-24 nucleotides also known to regulate the human genome mainly at the post-transcriptional level. MiRNAs were shown to play an important role in most biological processes such as apoptosis and in the pathogenesis of many diseases such as cardiovascular diseases and cancer. Recent developments of advanced molecular high-throughput technologies have enhanced our knowledge of miRNAs. MiRNAs can now be discovered, interrogated, and quantified in various body fluids, and hence can serve as diagnostic and therapeutic markers for many diseases. While most studies use blood as a sample source to measure circulating miRNAs as possible biomarkers for disease pathogenesis, fewer studies have assessed the role of salivary miRNAs in health and disease. This review aims at providing an overview of the current knowledge of the salivary miRNome, addressing the technical aspects of saliva sampling and highlighting the applicability of miRNA screening to clinical practice.

Analysis of periodontitis-associated miRNAs in gingival tissue, gingival crevicular fluid, saliva and blood plasma

OBJECTIVE

Periodontitis (PD) is a chronic inflammatory disease which is associated with multiple systemic comorbidities, including rheumatoid arthritis (RA), meanwhile the etiopathology of PD may be modulated by various factors including microRNA (miRNA). The present study aimed to reveal miRNAs associated with PD in gingival tissue, gingival crevicular fluid (GCF), saliva, plasma and to assess the possible influence of RA.

DESIGN

The cross-sectional study included 30 patients with PD and 31 periodontally healthy participants. A total of 25 participants were additionally diagnosed with RA. Microarray analysis of eight gingival tissue samples was performed and four PD-associated miRNAs were selected: miR-199a-5p, miR-483-5p, miR-3198 and miR-4299. Target miRNAs were further assessed by means of RT-qPCR in 61 gingival tissue samples and corresponding bodily fluids - GCF, saliva and plasma.

RESULTS

The upregulation of miR-199a-5p and downregulation of miR-4299 in gingival tissue was associated with the presence of PD and RA (P < 0.05). GCF level of miR-3198 was higher amongst participants with PD (P = 0.019) and showed a good diagnostic ability (AUC = 0.72, P = 0.008). Increased miR-199a-5p salivary level and decreased miR-199a-5p plasma level were observed amongst patients with worse clinical status of PD (P < 0.05). MiR-3198 and miR-4299 combination in GCF demonstrated AUC value of 0.86 and reached sensitivity of 68 % and specificity of 96 %.

CONCLUSIONS

Aberrant expression of miR-199a-5p, miR-483-5p, miR-3198, miR-4299 in gingival tissues is associated with the presence and/or severity of PD. MiR-3198, miR-4299 level in GCF and miR-199a-5p level in plasma strongly correlated with PD, demonstrating significant diagnostic performance.

MicroRNA-363-3p Inhibits the Expression of Renal Fibrosis Markers in TGF-β1-Treated HK-2 Cells by Targeting TGF-β2

This study aimed to explore the role of miR-363-3p in renal fibrosis (RF) in vitro. HK-2 cells were treated with transforming growth factor (TGF)-β1 for 72 h to establish an in vitro model of RF. Subsequently, western blot analysis and reverse transcription-quantitative PCR were used to detect the protein and mRNA expression levels of RF markers in TGF-β1-treated HK-2 cells, respectively. The results showed that the protein and mRNA expression levels of TGF-β2, α-smooth muscle actin (SMA), fibronectin, vimentin, collagen II and N-cadherin were increased, while the protein and mRNA expression levels of E-cadherin were decreased in TGF-β1-treated HK-2 cells. The level of miR-363-3p was significantly decreased in TGF-β1-treated HK-2 cells. TargetScan indicated that TGF-β2 was a direct target gene for miR-363-3p, which was further verified using dual luciferase reporter gene assays. Further analyses revealed that the increased protein and mRNA expression levels of TGF-β2, α-SMA, fibronectin, vimentin, collagen II, N-cadherin, increased phosphorylated-Smad3 protein level, and decreased E-cadherin protein and mRNA expression in TGF-β1-treated HK-2 cells were significantly reversed by miR-363-3p mimics. However, all the effects were suppressed by a TGF-β2-plasmid. The results suggested that miR-363-3p plays a protective role in RF by regulating the TGF-β2/Smad3 signaling pathway.

Salivary Micro-RNA and Oral Squamous Cell Carcinoma: A Systematic Review

Oral squamous cell carcinoma (OSCC) is a widespread malignancy with high mortality. In particular, a delay in its diagnosis dramatically decreases the survival rate. The aim of this systematic review was to investigate and summarize clinical results in the literature, regarding the potential use of salivary microRNAs (miRNAs) as diagnostic and prognostic biomarkers for OSCC patients. Twelve papers were selected, including both case-control and cohort studies, and all of them detected significantly dysregulated miRNAs in OSCC patients compared to healthy controls. Based on our results, salivary miRNAs might provide a non-invasive and cost-effective method in the diagnosis of OSCC, and also to monitor more easily its evolution and therapeutic response and therefore aid in the establishment of specific therapeutic strategies.

Potential therapeutic approaches of microRNAs for COVID-19: Challenges and opportunities

The coronavirus disease 2019 (COVID-19) emerges as current outbreak cause by Novel Severe Acute Respiratory Syndrome Corona Virus-2 (SARS-CoV-2). This infection affects respiratory system and provides uncontrolled systemic inflammatory response as cytokine storm. The main concern about SARS-CoV-2 pandemic is high viral pathogenicity with no specific drugs. MicroRNAs (miRs) as small non-coding RNAs (21–25 ​nt) regulate gene expression. The SARS-CoV-2 encoded-miRs affect human genes that involved in transcription, translation, apoptosis, immune response and inflammation. Also, they alter self-gene regulation and hijacked host miRs that provide protective environment to maintain its latency. On the other hand, Host miRs play critical role in viral gene expression to restrict infection. Over expression/inhibition of miRs might result in cell cycle irregularity, impaired immune response or cancer. In this manner, exact role of each miR should be specified. Mimic encoded-miRs like antagomirs showed successful result in phases of clinical trial prevent from negative effects of viral encoded-miRs. Products of mimic miRs are inexpensive corresponds to synthesis of primer; they are short and nanoscale in size. Although SARS-CoV-2 genome is undergoing evaluation, detection of exact molecular pathogenesis open up opportunities to for vaccine development. Salivaomics can evaluate SARS-CoV-2 genome, transcriptome, proteome and biomarkers like miRs in oral related and cancer disease. In this review, we studied the challenge and opportunities of miRs in therapeutic approach for SARS-CoV-2 infection, then overviewed the role of miRs in saliva droplet during SARS-CoV-2 infection and related cancer.

Salivary Extracellular DNA and DNase Activity in Periodontitis

Extracellular DNA (ecDNA) is a potential marker and predictor in several inflammatory diseases. Periodontitis, a chronic inflammatory disease, is associated with epithelial cell death and could lead to release of DNA. Our aim was to analyze salivary DNA concentration and deoxyribonuclease (DNase) activity in periodontitis patients. We hypothesized that salivary ecDNA will be higher than in controls and could serve as a marker of periodontitis severity. Samples of saliva were collected from 25 patients with chronic periodontitis and 29 age-matched controls. DNA was quantified fluorometrically in whole saliva, as well as in supernatants after centrifugation (depletion of cells at 1600× g) and in double-centrifuged supernatants (depletion of cell debris at 1600× g and 16,000× g). The subcellular origin of ecDNA was assessed using real-time PCR. In comparison to controls, patients with periodontitis had twofold higher salivary DNA (p < 0.01), higher mitochondrial DNA in centrifuged supernatants (p < 0.05) and lower nuclear ecDNA in double-centrifuged samples (p < 0.05). No correlations were found between salivary DNA and oral health status, but mitochondrial DNA positively correlated with papillary bleeding index in centrifuged samples. Salivary DNase activity was comparable between the groups. In conclusion, we proved that salivary DNA is higher in periodontitis. The source of the higher mitochondrial DNA in cell-free saliva and the causes of lower nuclear ecDNA remain to be elucidated. Further studies should focus on the role of mitochondrial DNA as a potential driver of inflammation in periodontitis.

The Liquid Biopsy in the Management of Colorectal Cancer: An Overview

Currently, there is a crucial need for novel diagnostic and prognostic biomarkers with high specificity and sensitivity in patients with colorectal cancer. A "liquid biopsy" is characterized by the isolation of cancer-derived components, such as circulating tumor cells, circulating tumor DNA, microRNAs, long non-coding RNAs, and proteins, from peripheral blood or other body fluids and their genomic or proteomic assessment. The liquid biopsy is a minimally invasive and repeatable technique that could play a significant role in screening and diagnosis, and predict relapse and metastasis, as well as monitoring minimal residual disease and chemotherapy resistance in colorectal cancer patients. However, there are still some practical issues that need to be addressed before liquid biopsy can be widely used in clinical practice. Potential challenges may include low amounts of circulating tumor cells and circulating tumor DNA in samples, lack of pre-analytical and analytical consensus, clinical validation, and regulatory endorsement. The aim of this review was to summarize the current knowledge of the role of liquid biopsy in the management of colorectal cancer.

A Traditional Korean Diet Alters the Expression of Circulating MicroRNAs Linked to Diabetes Mellitus in a Pilot Trial

The traditional Korean diet (K-diet) is considered to be healthy and circulating microRNAs (miRs) have been proposed as useful markers or targets in diet therapy. We, therefore, investigated the metabolic influence of the K-diet by evaluating the expression of plasma and salivary miRs. Ten women aged 50 to 60 years were divided into either a K-diet or control diet (a Westernized Korean diet) group. Subjects were housed in a metabolic unit-like condition during the two-week dietary intervention. Blood and saliva samples were collected before and after the intervention, and changes in circulating miRs were screened by an miR array and validated by individual RT-qPCRs. In the K-diet group, eight plasma miRs were down-regulated by array (p < 0.05), out of which two miRs linked to diabetes mellitus, hsa-miR26a-5p and hsa-miR126-3p, were validated (p < 0.05). Among five down-regulated salivary miRs, hsa-miR-92-3p and hsa-miR-122a-5p were validated, which are associated with diabetes mellitus, acute coronary syndrome and non-alcoholic fatty liver disease. In the control diet group, validated were down-regulated plasma hsa-miR-25-3p and salivary hsa-miR-31-5p, which are associated with diabetes mellitus, adipogenesis and obesity. The K-diet may influence the metabolic conditions associated with diabetes mellitus, as evidenced by changes in circulating miRs, putative biomarkers for K-diet.

Application of salivary noncoding microRNAs for the diagnosis of oral cancers

Oral cancer is on the rise globally and survival rates, despite improvements in clinical care, have not significantly improved. Early detection followed by immediate intervention is key to improving patient outcomes. The use of biomarkers has changed the diagnostic landscape for many cancers. For oral cancers, visual inspection followed by a tissue biopsy is standard practice. The discovery of microRNAs as potential biomarkers has attracted clinical interest but several challenges remain. These microRNAs can be found in bodily fluids such as blood and saliva which have been investigated as potential sources of biomarker discovery. As oral cancer is localized within the oral cavity, saliva may contain clinically relevant molecular markers for disease detection. Our review provides an outline of the current advances for the application of salivary microRNAs in oral cancer. We also provide a technical guide for the processing of salivary RNAs to ensure accurate clinical measurement and validation.

Salivary Small Extracellular Vesicles Associated miRNAs in Periodontal Status-A Pilot Study

This pilot study aims to investigate whether salivary small extracellular vesicle (sEV)-associated microRNAs could act as potential biomarkers for periodontal disease status. Twenty-nine participants (10 who were healthy, nine with gingivitis, 10 with stage III/IV periodontitis) were recruited and unstimulated whole saliva samples were collected. Salivary sEVs were isolated using the size-exclusion chromatography (SEC) method and characterised by morphology, EV-protein and size distribution using transmission electron microscopy (TEM), Western Blot and Nanoparticle Tracking Analysis (NTA), respectively. Ten mature microRNAs (miRNAs) in salivary sEVs and saliva were evaluated using RT-qPCR. The discriminatory power of miRNAs as biomarkers in gingivitis and periodontitis versus healthy controls was evaluated by Receiver Operating Characteristics (ROC) curves. Salivary sEVs were comparable to sEVs morphology, mode, size distribution and particle concentration in healthy, gingivitis and periodontitis patients. Compared to miRNAs in whole saliva, three significantly increased miRNAs (hsa-miR-140-5p, hsa-miR-146a-5p and hsa-miR-628-5p) were only detected in sEVs in periodontitis when compared to that of healthy controls, with a good discriminatory power (area under the curve (AUC) = 0.96) for periodontitis diagnosis. Our study demonstrated that salivary sEVs are a non-invasive source of miRNAs for periodontitis diagnosis. Three miRNAs that are selectively enriched in sEVs, but not whole saliva, could be potential biomarkers for periodontal disease status.

Clinical significance of miRNAs in autoimmunity

MicroRNAs (miRNAs) are evolutionally conserved, single-stranded RNAs that regulate gene expression at the posttranscriptional level by disrupting translation. MiRNAs are key players in variety of biological processes that regulate the differentiation, development and activation of immune cells in both innate and adaptive immunity. The disruption and dysfunction of miRNAs can perturb the immune response, stimulate the release of inflammatory cytokines and initiate the production of autoantibodies, and contribute to the pathogenesis of autoimmune diseases, including systemic lupus erythmatosus (SLE), rheumatoid arthritis (RA), primary biliary cholangitis (PBC), and multiple sclerosis (MS). Accumulating studies demonstrate that miRNAs, which can be collected by noninvasive methods, have the potential to be developed as diagnostic and therapeutic biomarkers, the discovery and validation of which is essential for the improvement of disease diagnosis and clinical monitoring. Recently, with the development of detection tools, such as microarrays and NGS (Next Generation Sequencing), large amounts of miRNAs have been identified and suggest a critical role in the pathogenesis of autoimmune diseases. Several miRNAs associated diagnostic biomarkers have been developed and applied clinically, though the pharmaceutical industry is still facing challenges in commercialization and drug delivery. The development of miRNAs is less advanced for autoimmune diseases compared with cancer. However, drugs that target miRNAs have been introduced as candidates and adopted in clinical trials. This review comprehensively summarizes the differentially expressed miRNAs in several types of autoimmune diseases and discusses the role and the significance of miRNAs in clinical management. The study of miRNAs in autoimmunity promises to provide novel and broad diagnostic and therapeutic strategies for a clinical market that is still in its infancy.

Cell-free miRNAs as non-invasive biomarkers in breast cancer: Significance in early diagnosis and metastasis prediction

Breast cancer is one of the genetic diseases causing a high mortality among women around the world. Despite the availability of advanced diagnostic tools and treatment strategies, the incidence of breast cancer is increasing every year. This is due to the lack of accurate and reliable biomarkers whose deficiency creates difficulty in early breast cancer recognition, subtypes determination, and metastasis prophecy. Although biomarkers such as ER, PR, Her2, Ki-67, and other genetic platforms e.g. MammaPrint®, Oncotype DX®, Prosigna® or EndoPredict® are available for determination of breast cancer diagnosis and prognosis. However, pertaining to heterogeneous nature, lack of sensitivity, and specificity of these markers, it is still incessant to overcome breast cancer burden. Therefore, a novel biomarker is urgently needed for therapeutic diagnosis and improving prognosis. Lately, it has become more evident that cell-free miRNAs might be useful as good non-invasive biomarkers that are associated with different events in carcinogenesis. For example, some known biomarkers such as miR-21, miR-23a, miR-34a are associated with molecular subtyping and different biomolecular aspects i.e. apoptosis, angiogenesis, metastasis, and miR-1, miR-10b, miR-16 are associated with drug response. Cell-free miRNAs present in human body fluids have proven to be potential biomarkers with significant prognostic and predictive values. Numerous studies have found a distinct expression profile of circulating miRNAs in breast tumour versus non-tumour and in early and advanced-stage, thus implicating its clinical relevance. This review article will highlight the importance of different cell-free miRNAs as a biomarker for early breast cancer detection, subtype classification, and metastasis forecast.

Salivary MicroRNA for Diagnosis of Cancer and Systemic Diseases: A Systematic Review

: Background: The aberrant expression of microRNAs (miRNAs) has been associated with several diseases, including cancer, inflammatory, and autoimmune conditions. Interest in salivary miRNAs as non-invasive tools for the diagnosis of malignancies and systemic diseases is rapidly increasing. The present systematic review was developed for answering the question: "Are salivary microRNAs reliable biomarkers for diagnosis of cancer and systemic diseases?"

METHODS

The application of inclusion and exclusion criteria led to the selection of 11 papers. Critical appraisals and quality assessments of the selected studies were performed through the National Institute of Health "Study Quality Assessment Tool" and the classification of the Oxford Center for Evidence-Based Medicine.

RESULTS

Seven studies reported statistically significant correlations between one or more salivary miRNAs and the investigated disease. The critical analysis allowed us to classify only two studies (18.2%) as having "good" quality, the rest being scored as "intermediate" (8; 73%) and "poor" (1; 9%). Evidence exists that salivary miR-940 and miR-3679-5p are reliable markers for pancreatic cancer and that miR140-5p and miR301a are promising molecules for the salivary diagnosis of gastric cancer.

CONCLUSIONS

Further studies, possibly avoiding the risk of bias highlighted here, are necessary to consolidate these findings and to identify new reliable salivary biomarkers.

Cell-Free microRNAs as Potential Oral Cancer Biomarkers: From Diagnosis to Therapy

Oral cavity cancer is the most frequent malignancy of the head and neck. Unfortunately, despite educational interventions for prevention and early diagnosis, oral cancer patients are often diagnosed in advanced stages associated with poor prognosis and life expectancy. Therefore, there is an urgent need to find noninvasive biomarkers to improve early detection of this tumor. Liquid biopsy has emerged as a valuable tool in medical oncology which provides new horizons for improving clinical decision making. Notably, cell-free microRNAs (miRNAs), a class of short non-coding RNAs, are emerging as novel noninvasive cancer biomarkers. Here, we provide an overview of the potential clinical application of cell-free miRNAs as diagnostic, prognostic, and therapeutic biomarkers in oral cancer.

miRNAs in liquid biopsy for oral squamous cell carcinoma diagnosis: Systematic review and meta-analysis

Oral squamous cell carcinoma (OSCC) is often diagnosed at advanced stages and is associated with poor survival rates. Increasing evidence suggests that microRNAs (miRNAs) present in liquid biopsies could be potential biomarkers for non-invasive OSCC diagnosis. Here, we performed a comprehensive meta-analysis to evaluate the overall diagnostic accuracy of blood and salivary miRNAs in detecting OSCC. A literature search using PubMed EMBASE, Web of Science, LILACS, Scopus, and the Cochrane Library was undertaken up to February 2019. Study quality was assessed with the Quality Assessment for Studies of Diagnostic Accuracy-2, and sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and their corresponding 95% confidence intervals (CIs) were calculated using a bivariate random-effect meta-analysis model. Meta-regression and subgroup analyses were performed to assess the heterogeneity. Twenty-five study units from 16 articles with 2562 subjects were included in this meta-analysis. The pooled sensitivity and specificity of blood and salivary miRNAs in the diagnosis of OSCC were 0.78 (95% CI: 0.76-0.80) and 0.82 (95% CI: 0.79-0.84), respectively, and the pooled positive and negative likelihood ratios were 4.31 (95% CI: 3.38-5.51) and 0.25 (95% CI: 0.20-0.32), respectively. The overall area under the curve was 0.91 (95% CI: 0.88-0.93), with a diagnostic odds ratio of 21.46 (95% CI: 13.37-34.45). These findings provide evidence regarding the potential clinical application of blood and salivary miRNAs as a novel, non-invasive, and accurate diagnostic tool for OSCC.

A Novel Saliva-Based miRNA Signature for Colorectal Cancer Diagnosis

Salivary microRNAs (miRNAs) are of high interest as diagnostic biomarkers for non-oral cancer. However, little is known about their value for colorectal cancer (CRC) detection. Our study aims to characterize salivary miRNAs in order to identify non-invasive markers for CRC diagnosis. The screening of 754 miRNAs was performed in saliva samples from 14 CRC and 10 healthy controls. The differential expressed miRNAs were validated by RT-qPCR in 51 CRC, 19 adenomas and 37 healthy controls. Receiver operating characteristic (ROC) curves and logistic regression models were performed to analyze the clinical value of these miRNAs. Twenty-two salivary miRNAs were significantly deregulated in CRC patients vs. healthy individuals (p < 0.05) in the discovery phase. From those, five upregulated miRNAs (miR-186-5p, miR-29a-3p, miR-29c-3p, miR-766-3p, and miR-491-5p) were confirmed to be significantly higher in the CRC vs. healthy group (p < 0.05). This five-miRNA signature showed diagnostic value (72% sensitivity, 66.67% specificity, AUC = 0.754) to detect CRC, which was even higher in combination with carcinoembryonic antigen (CEA) levels. Overall, after the first global characterization of salivary miRNAs in CRC, a five-miRNA panel was identified as a promising tool to diagnose this malignancy, representing a novel approach to detect cancer-associated epigenetic alterations using a non-invasive strategy.

Extracellular miRNAs as Biomarkers of Head and Neck Cancer Progression and Metastasis

Head and neck squamous cell carcinomas (HNSCCs) contribute to over 300,000 deaths every year worldwide. Although the survival rates have improved in some groups of patients, mostly due to new treatment options and the increasing percentage of human papillomavirus (HPV)-related cancers, local recurrences and second primary tumors remain a great challenge for the clinicians. Presently, there is no biomarker for patient surveillance that could help identify patients with HNSCC that are more likely to experience a relapse or early progression, potentially requiring closer follow-up or salvage treatment. MicoRNAs (miRNAs) are non-coding RNA molecules that posttranscriptionally modulate gene expression. They are highly stable and their level can be measured in biofluids including serum, plasma, and saliva, enabling quick results and allowing for repeated analysis during and after the completion of therapy. This has cemented the role of miRNAs as biomarkers with a huge potential in oncology. Since altered miRNA expression was described in HNSCC and many miRNAs play a role in radio- and chemotherapy resistance, cancer progression, and metastasis, they can be utilized as biomarkers of these phenomena. This review outlines recent discoveries in the field of extracellular miRNA-based biomarkers of HNSCC progression and metastasis, with a special focus on HPV-related cancers and radioresistance.

Saliva-derived cfDNA is applicable for EGFR mutation detection but not for quantitation analysis in non-small cell lung cancer

Background

Both quantitative and qualitative aspects of plasma cell‐free DNA (plasma cfDNA, pcfDNA) have been well‐studied as potential biomarkers in non‐small cell lung cancer (NSCLC). Accumulating evidence has proven that saliva also has the potential for the detection and analysis of circulating free DNA (saliva cfDNA, scfDNA).

Methods

In the current study, we aimed to explore the potential application of scfDNA in NSCLC diagnostics and consistency of epidermal growth factor receptor (EGFR) mutation detection in paired pcfDNA and scfDNA using droplet digital PCR (ddPCR) and analyze the relationship between EGFR mutations and clinical treatment response.

Results

In the quantitative cohort study, scfDNA concentration in NSCLC patients was no different from that in healthy donors, or in benign patients. ScfDNA concentration was significantly lower than pcfDNA concentration, yet they were not statistically significant in relevance (Spearman's rank correlation r = −0.123, P = 0.269). In the qualitative cohort study, the overall concordance rate of EGFR mutations between pcfDNA and scfDNA was 83.78% (31 of 37; k = 0.602; P < 0.001). EGFR mutation detection in paired pcfDNA and scfDNA was significantly correlated with the clinical treatment response (Spearman's rank correlation r = 0.664, P = 0.002).

Conclusions

Our results demonstrated that saliva might not be the idea material for a cfDNA quantitative test, and scfDNA concentration is not applicable for NSCLC diagnostics. Conversely, scfDNA was capable of acting as the supplement for EGFR mutations due to the coincidence rate of EGFR mutation detection between scfDNA and pcfDNA.

Targeting Cellular Metabolism Modulates Head and Neck Oncogenesis

Considering the great energy and biomass demand for cell survival, cancer cells exhibit unique metabolic signatures compared to normal cells. Head and neck squamous cell carcinoma (HNSCC) is one of the most prevalent neoplasms worldwide. Recent findings have shown that environmental challenges, as well as intrinsic metabolic manipulations, could modulate HNSCC experimentally and serve as clinic prognostic indicators, suggesting that a better understanding of dynamic metabolic changes during HNSCC development could be of great benefit for developing adjuvant anti-cancer schemes other than conventional therapies. However, the following questions are still poorly understood: (i) how does metabolic reprogramming occur during HNSCC development? (ii) how does the tumorous milieu contribute to HNSCC tumourigenesis? and (iii) at the molecular level, how do various metabolic cues interact with each other to control the oncogenicity and therapeutic sensitivity of HNSCC? In this review article, the regulatory roles of different metabolic pathways in HNSCC and its microenvironment in controlling the malignancy are therefore discussed in the hope of providing a systemic overview regarding what we knew and how cancer metabolism could be translated for the development of anti-cancer therapeutic reagents.

Circulating microRNAs as Potential Diagnostic and Prognostic Biomarkers in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer with high mortality, due to late diagnosis and limited treatment options. Blood miRNAs, which circulate in a highly stable, cell-free form, show promise as novel potential biomarkers for early detection of HCC. Whole miRNome profiling was performed to identify deregulated miRNAs between HCC and normal healthy (NH) volunteers. These deregulated miRNAs were validated in an independent cohort of HCC, NH and chronic Hepatitis B (CHB) volunteers and finally in a 3^rd cohort comprising NH, CHB, cirrhotic and HCC volunteers to evaluate miRNA changes during disease progression. The associations between circulating miRNAs and liver-damage markers, clinicopathological characteristics and survival outcomes were analysed to identify prognostic markers. Twelve miRNAs are differentially expressed between HCC and NH individuals in all three cohorts. Five upregulated miRNAs (miR-122-5p, miR-125b-5p, miR-885-5p, miR-100-5p and miR-148a-3p) in CHB, cirrhosis and HCC patients are potential biomarkers for CHB infection, while miR-34a-5p can be a biomarker for cirrhosis. Notably, four miRNAs (miR-1972, miR-193a-5p, miR-214-3p and miR-365a-3p) can distinguish HCC from other non-HCC individuals. Six miRNAs are potential prognostic markers for overall survival.

MiR-92a promotes the invasion and migration of colorectal cancer by targeting RECK

The up-regulation of miR-92a in human cancer happens frequently, and is related to an increase of metastasis and decreased survival. However, its functions in colorectal cancer (CRC) are largely unknown. This study aimed to investigate the regulatory effect of miR-92a on cell invasion and migration in colorectal cancer (CRC). A total of 158 patients with CRC were included, and in situ hybridization was used to predict the expression of miR-92a in the paraffin sections from the patients. Quantitative reverse transcription PCR was used to detect the expression of miR-92a and its target gene. Protein levels were determined by western blotting. Luciferase assays confirmed the direct target of miR-92a. Furthermore, cell invasion and migration were detected using Transwell and wound healing assays. The expression level of miR-92a in tumor tissues was upregulated compared with that of paired normal tissues and negatively correlated with the RECK protein level. The 3-year disease-free survival (DFS) and overall survival (OS) rates of miR-92a expression in the high group were significantly lower than those in the miR-92a-low group. The RECK 3'-UTR reporter activity assay suggested that the RECK gene was a direct target of miR-92a. After transfection of the miR-92a-mimic, the miR-92a levels were increased in HCT116 and SW620 cell lines, while the protein expression of RECK was decreased instead of the mRNA level, along with downregulation of matrix metalloproteinase (MMP) protein expression. Conversely, after transfection with miR-92a-inhibitor, the opposite trend was achieved. In conclusion, miR-92a promotes the invasion and migration of CRC through the RECK-MMP signaling pathway, and the upregulation of miR-92a was associated with poor long-term prognosis in CRC.

Oxidative stress markers in saliva and plasma differ between diet-controlled and insulin-controlled gestational diabetes mellitus

OBJECTIVES

The aims of the study were as follows: to investigate possible differences between plasma oxidative status (OS) in late-onset GDM and well-characterized healthy pregnant women (oral health, diet); to verify the existence of possible differences between GDMG1 (diet-treated) and GDMG2 (insulin-treated GDM); to determine whether oxidative stress markers could be detected in saliva.

MATERIAL AND METHODS

A total of 89 pregnant women (n = 89; 59 with GDM and 30 controls) were evaluated. Malondialdehyde (MDA), total antioxidant capacity (ORAC), inactivation of aldehyde dehydrogenase (I_ALDH), activity of glutathione peroxidase (GPx) and glutathione transferase (GST)) in plasma and/or saliva were analyzed.

RESULTS

The activity of GPx and GST in plasma was higher in GDMG2 as compared to GDMG1 and controls. Also, in GDMG2, elevated concentrations of salivary MDA and higher I_ALDH were observed. In contrast, GDMG1 had higher plasma ORAC and lower GPx activity as compared to controls, probably due to low-energy diet, high in antioxidants and fibers. Salivary and plasma OS were correlated and most significant for ORAC.

CONCLUSION

Oxidative stress were not observed in GDMG1 but were confirmed to be moderate in GDMG2. However, large variability of the analyzed markers in GDM groups encourages screening of all patients, regardless of the treatment option. Saliva may be considered useful for the estimation of oxidative stress levels in GDM populations.