MicroRNAs: New actors in the oral cancer scene

Exploring the role of microRNAs as diagnostic and prognostic biomarkers in canine mammary tumors

Canine mammary tumors (CMTs) represent a significant health concern in dogs, with a high incidence among intact female dogs. CMTs are a promising comparative model for human breast cancer, due to sharing several pathophysiological features. Additionally, CMTs have a strong genetic correlation with their human counterpart, including the expression of microRNAs (miRNAs). MiRNAs are a class of non-coding RNAs that play important roles in post-translational regulation of gene expression, being implicated in carcinogenesis, tumor progression, and metastasis. Moreover, miRNAs hold promise as diagnostic, prognostic, and metastatic biomarkers. Understanding the molecular mechanisms underlying CMTs is crucial for improving diagnosis, prognosis, and monitoring of treatments. Herein, we provide a comprehensive overview of the current knowledge on miRNAs in CMTs, highlighting their roles in carcinogenesis and their potential as biomarkers. Additionally, we highlight the current limitations and critically discuss the overarching challenges in this field, emphasizing the need for future research to translate miRNA findings into veterinary clinical practice.

Intronic miR-6741-3p targets the oncogene SRSF3: Implications for oral squamous cell carcinoma pathogenesis

Epigenetic silencing through methylation is one of the major mechanisms for downregulation of tumor suppressor miRNAs in various malignancies. The aim of this study was to identify novel tumor suppressor miRNAs which are silenced by DNA hypermethylation and investigate the role of at least one of these in oral squamous cell carcinoma (OSCC) pathogenesis. We treated cells from an OSCC cell line SCC131 with 5-Azacytidine, a DNA methyltransferase inhibitor, to reactivate tumor suppressor miRNA genes silenced/downregulated due to DNA methylation. At 5-day post-treatment, total RNA was isolated from the 5-Azacytidine and vehicle control-treated cells. The expression of 2,459 mature miRNAs was analysed between 5-Azacytidine and control-treated OSCC cells by the microRNA microarray analysis. Of the 50 miRNAs which were found to be upregulated following 5-Azacytidine treatment, we decided to work with miR-6741-3p in details for further analysis, as it showed a mean fold expression of >4.0. The results of qRT-PCR, Western blotting, and dual-luciferase reporter assay indicated that miR-6741-3p directly targets the oncogene SRSF3 at the translational level only. The tumor-suppressive role of miR-6741-3p was established by various in vitro assays and in vivo study in NU/J athymic nude mice. Our results revealed that miR-6741-3p plays a tumor-suppressive role in OSCC pathogenesis, in part, by directly regulating SRSF3. Based on our observations, we propose that miR-6741-3p may serve as a potential biological target in tumor diagnostics, prognostic evaluation, and treatment of OSCC and perhaps other malignancies.

Developments and future prospects of personalized medicine in head and neck squamous cell carcinoma diagnoses and treatments

BACKGROUND

Precision healthcare has entered a new era because of the developments in personalized medicine, especially in the diagnosis and treatment of head and neck squamous cell carcinoma (HNSCC). This paper explores the dynamic landscape of personalized medicine as applied to HNSCC, encompassing both current developments and future prospects.

RECENT FINDINGS

The integration of personalized medicine strategies into HNSCC diagnosis is driven by the utilization of genetic data and biomarkers. Epigenetic biomarkers, which reflect modifications to DNA that can influence gene expression, have emerged as valuable indicators for early detection and risk assessment. Treatment approaches within the personalized medicine framework are equally promising. Immunotherapy, gene silencing, and editing techniques, including RNA interference and CRISPR/Cas9, offer innovative means to modulate gene expression and correct genetic aberrations driving HNSCC. The integration of stem cell research with personalized medicine presents opportunities for tailored regenerative approaches. The synergy between personalized medicine and technological advancements is exemplified by artificial intelligence (AI) and machine learning (ML) applications. These tools empower clinicians to analyze vast datasets, predict patient responses, and optimize treatment strategies with unprecedented accuracy.

CONCLUSION

The developments and prospects of personalized medicine in HNSCC diagnosis and treatment offer a transformative approach to managing this complex malignancy. By harnessing genetic insights, biomarkers, immunotherapy, gene editing, stem cell therapies, and advanced technologies like AI and ML, personalized medicine holds the key to enhancing patient outcomes and ushering in a new era of precision oncology.

Unraveling the role of miRNAs in the diagnosis, progression, and drug resistance of oral cancer

Oral cancer (OC) is a widely observed neoplasm on a global scale. Over time, there has been an increase in both its fatality and incidence rates. Oral cancer metastasis is a complex process that involves a number of cellular mechanisms, including invasion, migration, proliferation, and escaping from malignant tissue through either lymphatic or vascular channels. MicroRNAs (miRNAs) are a crucial class of short non-coding RNAs recognized as significant modulators of diverse cellular processes and exert a pivotal influence on the carcinogenesis pathway, functioning either as tumor suppressors or as oncogenes. It has been shown that microRNAs (miRNAs) have a role in metastasis at several stages, including epithelial-mesenchymal transition, migration, invasion, and colonization. This regulation is achieved by targeting key genes involved in these pathways by miRNAs. This paper aims to give a contemporary analysis of OC, focusing on its molecular genetics. The current literature and emerging advancements in miRNA dysregulation in OC are thoroughly examined. This project would advance OC diagnosis, prognosis, therapy, and therapeutic implications.

Oral squamous cell carcinomas: state of the field and emerging directions

Oral squamous cell carcinoma (OSCC) develops on the mucosal epithelium of the oral cavity. It accounts for approximately 90% of oral malignancies and impairs appearance, pronunciation, swallowing, and flavor perception. In 2020, 377,713 OSCC cases were reported globally. According to the Global Cancer Observatory (GCO), the incidence of OSCC will rise by approximately 40% by 2040, accompanied by a growth in mortality. Persistent exposure to various risk factors, including tobacco, alcohol, betel quid (BQ), and human papillomavirus (HPV), will lead to the development of oral potentially malignant disorders (OPMDs), which are oral mucosal lesions with an increased risk of developing into OSCC. Complex and multifactorial, the oncogenesis process involves genetic alteration, epigenetic modification, and a dysregulated tumor microenvironment. Although various therapeutic interventions, such as chemotherapy, radiation, immunotherapy, and nanomedicine, have been proposed to prevent or treat OSCC and OPMDs, understanding the mechanism of malignancies will facilitate the identification of therapeutic and prognostic factors, thereby improving the efficacy of treatment for OSCC patients. This review summarizes the mechanisms involved in OSCC. Moreover, the current therapeutic interventions and prognostic methods for OSCC and OPMDs are discussed to facilitate comprehension and provide several prospective outlooks for the fields.

Role of Salivary MicroRNA and Cytokines in the Diagnosis and Prognosis of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most prevalent oral malignant tumor worldwide. An early diagnosis can have a major positive impact on its prognosis. Human saliva contains cytokines, DNA and RNA molecules, circulating cells, and derivatives of tissues and extracellular vesicles, among other factors that can serve as biomarkers. Hence, the analysis of saliva may provide useful information for the early diagnosis of OSCC for its prognosis. The objective of this review was to determine the potential usefulness of salivary biomarkers (cytokines and microRNA) to diagnose OSCC and improve its prognosis. A combination of salivary miRNA and proteomic data could allow a definitive and early diagnosis to be obtained. However, there remains a need to optimize and standardize the protocols used to quantify miRNAs.

MicroRNA as a Novel Biomarker in the Diagnosis of Head and Neck Cancer

Head and neck squamous cell carcinoma is the sixth most common cancer worldwide, with 890,000 new cases and 450,000 deaths in 2018, and although the survival statistics for some patient groups are improving, there is still an urgent need to find a fast and reliable biomarker that allows early diagnosis. This niche can be filled by microRNA, small single-stranded non-coding RNA molecules, which are expressed in response to specific events in the body. This article presents the potential use of microRNAs in the diagnosis of HNSCC, compares the advances in this field to other diseases, especially other cancers, and discusses the detailed use of miRNA as a biomarker in profiling and predicting the treatment outcome with radiotherapy and immunotherapy. Potential problems and difficulties related to the development of this promising technology, and areas on which future research should be focused in order to overcome these difficulties, were also indicated.

Genetic Drivers of Head and Neck Squamous Cell Carcinoma: Aberrant Splicing Events, Mutational Burden, HPV Infection and Future Targets

Head and neck cancers include cancers that originate from a variety of locations. These include the mouth, nasal cavity, throat, sinuses, and salivary glands. These cancers are the sixth most diagnosed cancers worldwide. Due to the tissues they arise from, they are collectively named head and neck squamous cell carcinomas (HNSCC). The most important risk factors for head and neck cancers are infection with human papillomavirus (HPV), tobacco use and alcohol consumption. The genetic basis behind the development and progression of HNSCC includes aberrant non-coding RNA levels. However, one of the most important differences between healthy tissue and HNSCC tissue is changes in the alternative splicing of genes that play a vital role in processes that can be described as the hallmarks of cancer. These changes in the expression profile of alternately spliced mRNA give rise to various protein isoforms. These protein isoforms, alternate methylation of proteins, and changes in the transcription of non-coding RNAs (ncRNA) can be used as diagnostic or prognostic markers and as targets for the development of new therapeutic agents. This review aims to describe changes in alternative splicing and ncRNA patterns that contribute to the development and progression of HNSCC. It will also review the use of the changes in gene expression as biomarkers or as the basis for the development of new therapies.

Interaction of tobacco chewing and smoking habit with interleukin 6 promoter polymorphism in oral precancerous lesions and oral cancer

OBJECTIVE

Our study aims to determine the influence of smoking or tobacco chewing and the association of Interleukin 6 (IL-6) polymorphism, where G is substituted by A at the position - 596 (IL-6 - 596 G/A) and substitution of G by cytosine (C) at position - 572 (IL-6 - 572 G/C) on the susceptibility of precancerous oral lesions and oral cancer.

MATERIALS AND METHODS

The participants consisted of 250 subjects among which 75 were suffering from oral cancer, 75 subjects with precancerous oral lesions and 100 were healthy controls. Single-nucleotide polymorphism study (SNP) was done by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP).

RESULTS

IL-6 - 596 G/A SNP revealed genotypes, GG, and GA in subjects with precancerous oral lesions and oral cancer, and AA genotype was not found in any subject. IL-6 - 596 G/A was strongly associated with oral precancerous lesions but not with oral cancer. The present study reports that smokers carrying GA for IL-6 - 596 G/A were at several folds higher risk of developing oral precancerous lesions. Smokers with GC and CC for IL-6 - 572 G/C were at higher risk of developing oral precancerous lesions. No significant interaction was observed between these habits and IL-6 - 596 G/A and IL-6 - 572 G/C SNP with oral cancer.

CONCLUSION

The interaction of variant A allele of IL-6 - 596 G/A and C allele of IL-6 - 572 G/C polymorphism with smoking and increases the risk of oral precancerous lesions. Tobacco chewing was not related with IL-6 - 596 G/A or IL-6 - 572 G/C in oral precancerous lesions or oral cancer.

CLINICAL RELEVANCE

The study will help to determine the susceptibility of individuals with smoking or chewing habits to the development of oral precancerous lesion and oral cancer by monitoring the IL-6 SNPs which can be used as a biomarker for risk determination.

Circulating microRNA Panel as a Potential Novel Biomarker for Oral Squamous Cell Carcinoma Diagnosis

Simple Summary

Although early detection of oral squamous cell carcinoma (OSCC) is considered vital, classical biomarkers have shown poor sensitivity and specificity for early detection and monitoring of OSCC. Therefore, identification of reliable and sensitive biomarkers allowing for early detection and monitoring of OSCC is of the utmost importance. In this study, we successfully identified significantly upregulated or downregulated microRNAs in OSCC patients, and reported that a combination of six microRNAs could distinguish between OSCC and the control group with a higher degree of accuracy. Furthermore, compared with serum squamous cell carcinoma (SCC) antigen, the miRNA panel reflected the presence of OSCC accurately. The present results suggest that the combined microRNA panel based on serum microRNA levels shows potential as a novel diagnostic biomarker of OSCC.

Abstract

A lack of reliable biomarkers for oral squamous cell carcinoma (OSCC) poses a major clinical issue. The sensitivity and specificity of classical serum tumor markers, such as the squamous cell carcinoma antigen (SCC-Ag), are quite poor, especially for early detection. This study aimed to identify specific serum miRNAs potentially serving as OSCC biomarkers. The expression levels of candidate miRNAs in serum samples from 40 OSCC patients and 40 healthy controls were quantitatively analyzed via microarray and reverse transcription PCR (RT-PCR) analyses. To enhance the accuracy of detection, we used Fisher’s linear discriminant analysis to establish a diagnostic model that incorporated a combination of selected miRNAs. Consequently, miR-19a and miR-20a were significantly upregulated in the patient group (p = 0.014 and 0.036, respectively), whereas miR-5100 was downregulated (p = 0.001). We found that a combination of six miRNAs (miR-24, miR-20a, miR-122, miR-150, miR-4419a, and miR-5100) could distinguish between OSCC and the control group with a higher degree of accuracy (Area Under the Curve, AUC: 0.844, sensitivity: 55%, and specificity: 92.5%). Furthermore, compared to serum SCC antigen, the 6-miRNA panel could accurately detect the presence of OSCC. The present specific miRNAs panel may serve as a novel candidate biomarker of oral cancer.

Expression levels and clinical significance of miR-203 and miR-133b in laryngeal carcinoma

The present study aimed to investigate the expression levels and clinical significance of microRNA (miR)-203 and miR-133b in laryngeal carcinoma. A total of 154 patients with laryngeal carcinoma (research group) along with 100 healthy individuals (control group) were enrolled in the study. The patients were admitted to Yidu Central Hospital of Weifang (Weifang, China) from February 2016 to October 2018. Fasting venous blood (5 ml) was extracted from all subjects to determine the expression levels of serum miR-203 and miR-133b by reverse transcription-quantitative polymerase chain reaction (PCR) and to compare them among patients with different pathological characteristics. Receiver operating characteristic (ROC) curves were plotted to analyze the diagnostic values of miR-203 and miR-133b for laryngeal carcinoma. The research group showed significantly lower expression levels of miR-203 and miR-133b than the control group (P<0.05). According to ROC curve analysis, when the cut-off value was 0.659, the sensitivity and specificity of miR-203 in diagnosing laryngeal carcinoma were 60.00 and 90.26%, respectively, whereas when the cut-off value was 1.398, the sensitivity and specificity of miR-133b were 55.00 and 87.66%, respectively. The sensitivity and specificity of the joint detection were 70.00 and 83.77%, respectively, when the cut-off value was 0.416. In the research group, miR-203 was expressed significantly different in patients with different pathological stages and tumor types (P<0.050). The expression of miR-133b varied significantly in patients with different pathological stages, differentiation degrees and lymph node metastasis (P<0.050). In conclusion, miR-203 and miR-133b were expressed at low levels in patients with laryngeal carcinoma. The expression of miR-203 was related to tumor-node-metastasis (TNM) stage and tumor type, whereas the expression of miR-133b was related to TNM stage, differentiation degree, as well as lymph node metastasis. Joint detection of miR-203 and miR-133b is expected to be an excellent marker for the diagnosis and treatment of laryngeal carcinoma.

MicroRNA-1179 suppresses the proliferation and enhances vincristine sensitivity of oral cancer cells via induction of apoptosis and modulation of MEK/ERK and PI3K/AKT signalling pathways

The role of miR-1179 in the development of cancer has been proved by different studies. However, the expression profile and role of miR-1179 is yet to be explored in human oral cancer. Consistently, this study was undertaken to explore the molecular role of miR-1179 in regulation of the human oral cancer development and progression. The results showed miR-1179 to be significantly (p < 0.05) overexpressed in all the oral cancer cell lines relative to normal cells. The repression of miR-1179 transcript levels not only suppressed the proliferation of oral cancer cells but also increased their sensitivity to vincristine. The decline in proliferative rates was attributed to induction of autophagy in oral cancer cells as confirmed by transmission electron microscopic analysis. Western blot analysis showed that the expression of LC3B-II increased and that of beclin 1 decreased while LC3B-I expression remained constant upon miR-1179 inhibition. Inhibition of miR-1179 caused significant decrease in the migration and invasion of the oral cancer cells. The migration and invasion found to be 47% and 32% for SCC-9 and 24% and 28% for SCC-25 cells upon miR-1179 inhibition. At molecular level, the miR-1179 was shown to exert its anticancer effects via deactivation of MEK/ERK and PI3K/AKT signalling cascades. In conclusion, the findings point towards the potential of miR-1179 in the treatment of oral cancer.

Evaluating the role of microRNAs alterations in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) accounts for nearly 90 percent of oral cavity malignancies and is one of the most widespread oral cancers in the world. The microRNAs (miRNAs or miRs) have an important role in cellular processes comprising cell cycle, differentiation, and also apoptosis. MiRNAs are also implicated in the progression of cancers, including OSCC, through a variety of signaling pathways. One of the most significant signaling pathways in OSCC is the PI3K / Akt pathway that has been illustrated to be under the tight regulation of miRNAs. Deregulation or activation of the PI3K / Akt pathway due to mutations has been revealed to be implicated in the development of oral cancer. According to studies, more than 47% of HNSCC and around 38% of OSCC samples indicate at least one molecular alteration in this signaling pathway. The potential of miRNAs for their use as therapeutic tools in the diagnosis as well as treatment of numerous diseases have been confirmed. In the current review, we summarize miRNAs and their possible mechanisms as well as their functions in OSCC advancement and progression.

MicroRNA-345 functions as a tumor suppressor via targeting ZEB2 in oral squamous cell carcinoma

OBJECTIVE

The objective of this study was to explore the role of miRNAs in OSCC and to identify potential novel biomarkers or therapeutic agents in OSCC treatment.

DESIGN

Microarray analysis and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were performed to identify and verify differentially expressed miRNAs in OSCC tissues. The migration, invasion, proliferation and cell cycle of OSCC cells were analyzed to determine the function of miR-345 in OSCC development. Bioinformatics analysis and Dual-luciferase reporter assays were performed to identify and verify the target of miR-345.

RESULTS

The results showed a total of 17 miRNAs with significantly different expression in OSCC tissues (5 upregulated miRNAs and 12 downregulated miRNAs), including miR-345. The microarray results were also validated by qRT-PCR using 22 pairs of cancerous tissues and matched non-cancerous healthy samples. In particular, miR-345 expression was significantly lower in OSCC tissues. In addition, overexpression of miR-345 mimics in OSCC cells significantly inhibited their migration, invasion and proliferation while inducing cell cycle arrest in the G1 phase. Bioinformatics analysis predicted ZEB2 (zinc finger E-box-binding homeobox 2) as a potential target of miR-345, and luciferase reporter assays confirmed that miR-345 targeted ZEB2 through direct binding the 3' untranslated region of ZEB2. Furthermore, miR-345 overexpression in OSCC reduced both mRNA and protein expression of ZEB2.

CONCLUSIONS

The results of this study indicated that miR-345 functions as a tumor suppressor to target ZEB2 in OSCC. These findings suggest that the miR-345/ZEB2 axis may be used as a potential therapeutic target in OSCC treatment.

MicroRNA's - The vibrant performers in the oral cancer scenario

MicroRNAs (miRNAs) are a family of small non-coding (18–22 nucleotide) RNA molecules. These molecules regulate gene expression by either inhibiting mRNA translation or by degrading mRNA. A single miRNA can control the expression of target genes, and the expression of a target gene can be regulated by multiple miRNAs. They are key regulators of various biological and pathological processes. These include cell proliferation, development and tumorigenesis. Novel studies have discovered definite signature miRNAs in the initiation and progression of cancers. Interestingly, miRNAs have also been found in fragile genomic sites that are associated with increased cancer risk.

These micro RNAs regulate the expression of several genes that play a crucial role in the transition of normal oral mucosa through dysplasia to malignancy. The aim of this review is to recapitulate the current understanding of the many miRNAs that have been identified, the genes that they target and the role that they play in the carcinogenic pathway. The review also highlights the prospective role of miRNAs in the diagnosis, prognosis and treatment of oral cancers.

Construction of an Autonomous Nonlinear Hybridization Chain Reaction for Extracellular Vesicles-Associated MicroRNAs Discrimination

Extracellular vesicles (EVs) have emerged as promising tumor biomarkers for early cancer diagnosis, as primary tumor-secreted EVs carry characteristic molecular information on parent cells. It is thus desirable to realize the efficient discrimination of the signatured EVs-associated microRNAs (miRNAs) with low expression and subtle variation. Here, we introduce an autonomous nonlinear enzyme-free signal amplification paradigm for EVs discrimination through a highly sensitive and selective detection of their inherent miRNAs in situ. Our proposed amplifier consists of a modularized DNAzyme-amplified two-stage cascaded hybridization chain reaction (CHCR-DNAzyme) circuit, where the analyte-generated output of the preceding hybridization chain reaction (HCR1) stage serves as input to motivate the following hybridization chain reaction (HCR2) stage and the concomitant assembly of numerous DNAzyme biocatalysts. By incorporating a flexibly configurable sensing module, this modular CHCR-DNAzyme circuit can further extend to "plug-and-play" sensing mode that enables the miRNA assay with high specificity. The sophisticated design and the detecting performance of our CHCR-DNAzyme scheme were systematically investigated in vitro. The optimized CHCR-DNAzyme system was further applied for distinguishing EVs derived from different cells through the amplified detection of a putative miRNA biomarker in EVs. This compact CHCR-DNAzyme amplifier provides a universal and facile toolbox for highly efficient identification of multiple miRNAs-involved EVs and thus holds great potential for early cancer diagnosis.

miR‑543 acts as a novel oncogene in oral squamous cell carcinoma by targeting CYP3A5

MicroRNAs (miRNAs/miRs) are small non-coding RNAs that can act as oncogenes or tumor-suppressor genes in human cancer. Previous studies have revealed that abnormal expression of miRNAs is closely associated with tumor cell cycle, differentiation, growth and apoptosis. miR-543 is expressed abnormally in a wide variety of cancers and has been associated with cellular proliferation, apoptosis, and invasion; however, the effect of miR-543 remains unknown in oral squamous cell carcinoma (OSCC). In the present study, the expression level of miR-543 in OSCC cell lines and tissues was investigated by RT-qPCR. A series of experiments was then performed to elucidate the functions of miR-543 in OSCC, such as CCK-8 assay, colony formation assay, flow cytometry, cell cycle distribution assay and cell apoptosis assay and Transwell assay. miR-543 expression was significantly upregulated in tumors from patients with OSCC and in OSCC cell lines. Overexpression of miR-543 promoted the proliferation, invasion and migration of OSCC cell lines, and inhibited cell apoptosis. In addition, the present study identified cytochrome P450 family 3 subfamily A member 5 (CYP3A5) as a direct target of miR-543 using software analysis and dual-luciferase reporter assays. In conclusion, the results of the present study suggest that miR-543 acts as a tumor promoter and serves a vital role in OSCC proliferation and invasion. These results confirm that miR-543 may serve as a potential novel target for the treatment of OSCC.

Oral squamous cell carcinoma-derived exosomes promote M2 subtype macrophage polarization mediated by exosome-enclosed miR-29a-3p

This study aims to explore the mechanism of the signal transmission between oral squamous cell carcinoma (OSCC) and unpolarized stromal immune macrophages mediated by OSCC-derived exosomes (OSCC-Exo). Polarization of macrophages was found by detection of the level of protein markers or specific components for M1 subtype or M2 subtype macrophages, respectively. Exosomes extracted from two OSCC cell lines, which might have been transfected with micro-RNA (miR)-29a-3p inhibitor or mimic, were cocultured with macrophages to ensure the effect of exosome-enclosed miR-29a-3p on the polarization of macrophages. miR-29a-3p is highly expressed, suppressor of cytokine signaling 1 (SOCS1) is low expressed and phosphorylated signal transduction and transcriptional activator 6 (p-STAT6) is highly expressed in OSCC tissues. Upregulation of miR-29a-3p is observed in OSCC-derived exosomes. When cocultured, OSCC-derived exosomes promote M2 subtype macrophage polarization and the medium of the coculture promotes the proliferation and invasion of SCC-9 and CAL-27 cells. After interfered silencing miR-29a-3p of OSCCs, SCC-9- and CAL-27 cell-derived exosomes inhibit M2 subtype macrophage polarization. On the other hand, cellular highly expressed miR-29a-3p of macrophages enhances M2 subtype macrophage polarization. Moreover, such macrophages promote the proliferation and invasion of SCC-9 and CAL-27. SOCS1 is a direct target for miR-29a-3p and could be negatively regulated by miR-29a-3p. Moreover, SOCS1 overexpression reverses the activity of SOCS1/STAT6 signals of macrophages and cell proliferation and invasion of OSCCs induced by miR-29a-3p overexpression. Also, overexpressed SOCS1 in macrophages counteracts the impact of OSCC-derived exosomes in M2 subtype macrophage polarization. Exosome-enclosed miR-29a-3p promotes tumor growth in nude mice with xenograft. OSCC-derived exosomes promote M2 subtype macrophage polarization mediated by exosome-enclosed miR-29a-3p, and the mechanism by miR-29a-3p is the activity of SOCS1/STAT6 signals in macrophages.

miR-23a-3p suppresses cell proliferation in oral squamous cell carcinomas by targeting FGF2 and correlates with a better prognosis: miR-23a-3p inhibits OSCC growth by targeting FGF2

Oral squamous cell carcinomas (OSCCs) are one of the most ubiquitous malignancies the world over, and are accompanied by a high mortality. microRNAs (miRNAs) have increasingly garnered attention with regards to the roles they play in initiation and progression of various kinds of cancers, including OSCC. It has been reported, that miR-23a-3p promotes the development of tumors for prostate cancer, gastric cancer and gliomas. The functions of miR-23a-3p in OSCC however, remain unclear. In this study, fibroblast growth factor 2 (FGF2) is revealed as a direct target of miR-23a-3p, based on luciferase assays and immunoblotting. The expression of miR-23a-3p and FGF2 were found to be significantly downregulated and upregulated in OSCC tissues respectively. This indicates a reverse correlation between miR-23a-3p and FGF2 levels. Using in vitro approaches we ascertained that miR-23a-3p might contribute to the inhibition of growth and inhibition through increasing apoptosis in OSCC cells; while an inhibitor of miR-23a-3p could reverse this effect. Examination of a clinical cohort of OSCC patients suggested that reduced expression of miR-23a-3p is correlated with more advanced cancerous stage and poorer differentiation of OSCC cell. Additionally, a survival analysis and the Cox-hazard regression model showed that higher levels of miR-23a-3p can be used reliably for prognosis of OSCC patients. This study indicates that miR-23a-3p might suppress tumor proliferation, invasion and promote apoptosis of OSCC by targeting FGF2. miR-23a-3p has the potential to be used as prognostic indicator, and could be exploited as a therapeutic reagent for OSCC in the future.

MicroRNA-transcription factor network analysis reveals miRNAs cooperatively suppress RORA in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) represents over 90% of oral cancer incidence, while its mechanisms of tumorigenesis remain poorly characterized. In this study, we applied RNA-seq and microRNA-seq methodologies in four pairs of cancer and adjacent normal tissues to profile the contribution of miRNAs to tumorigenesis-altered functional pathways by constructing a comprehensive miRNA-mediated mRNA regulatory network. There were 213 differentially expressed (DE) miRNAs and 2172 DE mRNAs with the involvement of negative miRNA-mRNA interactions identified by at least two pairs of cancerous tissues. GO analysis revealed that the upregulated microRNAs significantly contributed to a global down-regulation of a number of transcription factors (TFs) in OSCC. Among the negative regulatory networks between the selected miRNAs (133) and TFs (167), circadian rhythm genes (RORA, RORB, RORC, and CLOCK) simultaneously regulated by multiple microRNAs were of particular interest. For instance, RORA transcript was predicted to be targeted by 25 co-upregulated miRNAs, of which, miR-503-5p, miR-450b-5p, miR-27a-3p, miR-181a-5p and miR-183-5p were further validated to directly target RORA, resulting in a stronger effect on RORA suppression together. In addition, we showed that the mRNA and protein expression levels of RORα were significantly decreased in most OSCC samples, associated with advanced clinical stage and poor prognosis. RORα significantly suppressed the proliferation of OSCC cells in vitro and in vivo. Attenuated RORα decreased p53 protein expression and suppressed p53 phosphorylation activity. Altogether, our results strongly suggest the importance of the role of miRNAs in regulating the activity of circadian rhythm-related TFs network during OSCC tumorigenesis, and provide further clues to understand the clinical link between circadian rhythm and cancer therapy.

Differential expression of hsa-miR-221, hsa-miR-21, hsa-miR-135b, and hsa-miR-29c suggests a field effect in oral cancer

BACKGROUND

The theory of field effect suggests that the tumor-adjacent area, besides histopathologically normal, undergoes genetic and epigenetic changes that can eventually affect epithelial homeostasis, predisposing the patient to cancer development. One of the many molecular changes described in cancer are microRNAs (miRNAs), which regulates the expression of important genes during carcinogenesis. Thus, the aim of this study was to investigate the field effect in oral cancer.

METHODS

We investigated the differential expression profile of four miRNAs (hsa-miR-221, hsa-miR-21, hsa-miR-135b, and hsa-miR-29c) in cancerous oral tissue, in tumor-adjacent tissue and and in non-cancerous tissue samples from healthy volunteers.

RESULTS

Our results showed significant overexpression profiles of all four studied miRNAs in cancerous oral tissue compared to non-cancerous samples, as well as in tumor-adjacent tissue compared to cancer-free tissue. No significant difference was found when comparing the expression profile of cancerous and tissue-adjacent tissue groups. We found a negative correlation between the expression of hsa-miR-21 expression and STAT3 in oral squamous cell carcinoma.

CONCLUSION

These results suggest that the tissue adjacent to cancer cannot be considered a normal tissue because its molecular aspects are significantly altered. Our data corroborates the hypothesis of field cancerization.

A Noninvasive Test for MicroRNA Expression in Oral Squamous Cell Carcinoma

MicroRNAs have recently been proposed as non-invasive biomarkers in Oral Squamous Cell Carcinoma (OSCC). The aim of this study was to analyze the expression of a panel of miRNAs in epithelial cells collected by oral brushing from OSCCs from regenerative areas after OSCC surgical resection and from their respective normal distant mucosa. Oral brushing specimens were collected from 24 healthy donors, 14 OSCC patients with specimens from tumour and normal distant mucosa, and from 13 patients who had OSCC resection, with samples from regenerative areas after OSCC resection and normal distant mucosa. Expression levels of eight targets (miR-21, miR-375, miR-345, miR-181b, miR-146a, miR-649, miR-518b, and miR-191) were evaluated by real-time Polymerase Chain Reaction (PCR). A highly significant between-group difference was found for miR-21 (F = 6.58, p < 0.001), miR-146a (F = 6.974, p < 0.001), and miR-191 (F = 17.07, p < 0.001). The major difference was observed between samples from healthy donors and from OSCC brushing, whereas no significant differences were observed between areas infiltrated by OSCC and their respective normal distant mucosa. Furthermore, altered expression of miR-146a and miR-191 was also observed in regenerative areas after OSCC resection.

CONCLUSIONS

Oral brushing could be proposed as a noninvasive method to study microRNA expression in oral mucosa in OSCC patients.

Diagnostic and prognostic relevance of salivary microRNA-21, -125a, -31 and -200a levels in patients with oral lichen planus - a short report

BACKGROUND

Oral lichen planus (OLP), a relatively common chronic inflammatory disease of the oral mucosa, is considered to be a premalignant disorder of the oral cavity. Previously, several biomarkers have been tested for their diagnostic potential. Here, we aimed to investigate the diagnostic potential of four miRNAs, miR-21, -125a, -31 and -200a, known to be involved in oral squamous cell carcinoma (OSCC) development, in the saliva of OLP patients as also their putative relation to OSCC development in these patients.

MATERIALS AND METHODS

Saliva samples from 30 patients with OLP were collected, 15 of whom were diagnosed with dysplasia upon histopathologic examination. In addition, 15 saliva samples from patients with OSCC and 15 saliva samples from healthy donors were collected. After RNA extraction, the respective miRNA levels were assessed by quantitative RT-PCR.

RESULTS

We found that the miR-21 levels were significantly increased in saliva samples derived from patients with OLP, dysplastic OLP and OSCC, compared to those from healthy controls (p = 0.012, p = 0.0017 and p < 0.0001, respectively). Conversely, significant decreases in miR-125a levels were found in the OLP, dysplastic OLP and OSCC samples, compared to those from healthy controls (p < 0.0014, p < 0.0001 and p < 0.0001, respectively). In addition, significant increases in miR-31 levels were found in samples derived from dysplastic OLP and OSCC patients, but not in those from nondysplastic OLP patients, compared to those in healthy controls (p = 0.01 and p = 0.004, respectively). Finally, we found that the miR-200a levels were significantly decreased only in samples derived from OSCC patients (p < 0.0001).

CONCLUSIONS

From our data we conclude that increased miR-21 levels in conjunction with decreased miR-125a levels in saliva of OLP patients may be indicative for a poor prognosis. Conversely, we conclude that lack of significant alterations in miR-31 and miR-200a levels in saliva of OLP patients may be indicative for absence of malignant transformation.

Meta-Analysis of miRNAs and Their Involvement as Biomarkers in Oral Cancers

Oral Squamous Cell Carcinoma (OSCC) is one of the most common cancers worldwide. Recent studies have highlighted the role of miRNA in disease pathology, indicating its potential use as an early diagnostic marker. Dysregulated expression of miRNAs is known to affect cell growth, and these may function as tumor suppressors or oncogenes in various cancers. The main objective of this study was to characterize the extracellular miRNAs involved in oral cancer (OC) that can potentially be used as biomarkers of OC. A total of 318 miRNAs involved in oral carcinoma were shortlisted. Differentially expressed genes (DEGs) of oral carcinoma from reported experiments were identified. Common genes between lists of DEGs of OC of each miRNA were identified. These common genes are the targets of specific miRNA, which may be used as biomarkers of OC. A list of significant biomarkers for cancer was generated like CDH2 and CDK7, and functional enrichment analysis identified the role of miRNAs in major pathways like cell adhesion molecules pathway affected by cancer. We observed that at least 25 genes like ABCF3, ALDH2, CD163L1, and so forth are regulated by a maximum number of miRNAs; thereby, they can be used as biomarkers of OC.

MiR-31-5p-ACOX1 Axis Enhances Tumorigenic Fitness in Oral Squamous Cell Carcinoma Via the Promigratory Prostaglandin E2

During neoplastic development, a multitude of changes in genome-encoded information are progressively selected to confer growth and survival advantages to tumor cells. microRNAs-mRNAs regulatory networks, given their role as a critical layer of robust gene expression control, are frequently altered in neoplasm. However, whether and how these gene perturbations impact metabolic homeostasis remains largely unresolved.

Methods: Through targeted miRNA expression screening, we uncovered an oral squamous cell carcinoma (OSCC)-associated miRNAome, among which miR-31-5p was identified based on extent of up-regulation, functional impact on OSCC cell migration and invasion, and direct regulation of the rate-limiting enzyme in peroxisomal β-oxidation, ACOX1.

Results: We further found that both miR-31-5p and ACOX1 underpin, in an antagonistic manner, the overall cellular lipidome profiles as well as the migratory and invasive abilities of OSCC cells. Interestingly, the extracellular levels of prostaglandin E2 (PGE2), a key substrate of ACOX1, were controlled by the miR-31-5p-ACOX1 axis, and were shown to positively influence the extent of cell motility in correlation with metastatic status. The promigratory effect of this metabolite was mediated by an elevation in EP1-ERK-MMP9 signaling. Of note, functional significance of this regulatory pathway was further corroborated by its clinicopathologically-correlated expression in OSCC patient specimens.

Conclusions: Collectively, our findings outlined a model whereby misregulated miR-31-5p-ACOX1 axis in tumor alters lipid metabolomes, consequently eliciting an intracellular signaling change to enhance cell motility. Our clinical analysis also unveiled PGE2 as a viable salivary biomarker for prognosticating oral cancer progression, further underscoring the importance of lipid metabolism in tumorigenesis.

A Looking-Glass of Non-coding RNAs in oral cancer

Oral cancer is a multifactorial pathology and is characterized by the lack of efficient treatment and accurate diagnostic tools. This is mainly due the late diagnosis; therefore, reliable biomarkers for the timely detection of the disease and patient stratification are required. Non-coding RNAs (ncRNAs) are key elements in the physiological and pathological processes of various cancers, which is also reflected in oral cancer development and progression. A better understanding of their role could give a more thorough perspective on the future treatment options for this cancer type. This review offers a glimpse into the ncRNA involvement in oral cancer, which can help the medical community tap into the world of ncRNAs and lay the ground for more powerful diagnostic, prognostic and treatment tools for oral cancer that will ultimately help build a brighter future for these patients.

miR-582-5p inhibits invasion and migration of salivary adenoid cystic carcinoma cells by targeting FOXC1

Objective

Neurotropism of salivary adenoid cystic carcinoma (SACC) and pulmonary metastasis may lead to in treatment failure. miR-582-5p plays important roles in tumorigenesis, invasion and migration. Here, we aim to determine the effect of miR-582-5p and its role in SACC invasion and metastasis.

Methods

Six primary human SACC samples and matching adjacent normal tissues were analyzed by microarray analysis. Next, quantitative real-time PCR was carried out to evaluate miR-582-5p expression in 16 primary human SACC samples and matching adjacent normal tissues. Cell invasion and migration were also analyzed, and a luciferase reporter assay and western analysis were conducted. Cell growth and apoptosis assay were performed to confirm the effect of miR-582-5p and Forkhead box C1 (FOXC1) siRNA in cell proliferation and apoptosis. SACC tumorigenesis and metastasis were investigated in vivo experiment. Clinical samples from 110 patients were analyzed using in situ hybridization and immunohistochemistry.

Results

Microarray analysis revealed that miR-582-5p was significantly downregulated in the SACC samples compared with the matching adjacent normal tissues. Regulation of miR-582-5p expression significantly influenced the migration, invasion and proliferation ability of SACC cells by targeting FOXC1. E-cadherin was increased, while vimentin and snail were decreased with downregulation of FOXC1, suggesting that FOXC1 may regulate the epithelial-to-mesenchymal transition (EMT) of SACC cells by transactivating snail. In vivo, miR-582-5p overexpression suppressed the tumorigenesis and pulmonary metastasis of SACC. Lower expression of miR-582-5p expression predicts unfavorable prognoses and high rates of metastasis.

Conclusions

miR-582-5p could suppress effect on the process of invasion and migration in SACC cell lines, and this could occur through its target gene FOXC1.

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.

MicroRNA-27b inhibits cell proliferation in oral squamous cell carcinoma by targeting FZD7 and Wnt signaling pathway

This study intended to investigate the role of microRNA-27b (miR-27b) in proliferation of oral squamous cell carcinoma (OSCC) cells and to explore the potential molecular mechanism. Cell proliferation was detected by MTT assay. The expression levels of miR-27b, Frizzled7 (FZD7), cyclin D1 and c-myc were detected by quantitative real time polymerase chain reaction (qRT-PCR). The protein expression level of FZD7 was detected by western blot analysis. The relationship between miR-27b and FZD7, and the activity of Wnt signaling pathway were determined using luciferase reporter assay. The miR-27b expression in OSCC cell lines was significantly decreased compared with control. Overexpression of miR-27b remarkably inhibited OSCC cell proliferation. Additionally, miR-27b could target and inhibit FZD7 expression and decrease the activity of Wnt signaling pathway.miR-27b could inhibit OSCC cell proliferation through inhibiting FZD7 and FZD7-mediated Wnt signaling pathway.

The differential regulation of microRNAs is associated with oral cancer

Oral squamous cell carcinoma (OSCC), is the most frequently occurring malignant head and neck tumor, generally it exhibits a poor prognosis, and metastasis is the main cause of death in these cancer patients. The discovery of reliable prognostic indicators for tumors progression would greatly improve clinical treatments. MicroRNAs (miRNAs) play a critical role in the degradation of mRNA and the inhibition of protein synthesis. The miRNAs function either as tumor suppressors or as oncogenes in tumorigenesis, and little is known about the clinical significance of miRNA expression profiles in oral cancers. In the present study, we investigated the expression profiles of miR-375, miR-204 and miR-196a in 39 healthy and tumor tissue pairs of oral cancer patients using TaqMan real-time quantitative polymerase chain reaction (qPCR). The predicted target genes for miR-375, miR-204 and miR-196a were confirmed using luciferase reporter-based assays and western blot analyses. In oral cancer tissue, the expression of miR-375 and miR-204 decreased, whereas the expression of miR-196a was significantly elevated. In OSCC, HOXB8 and p27 (CDKN1B) were the direct target genes of miR-196a, whereas HMGA2 was the direct target gene of miR-204. HOXB8 and p27 (CDKN1B) protein expression levels were inhibited by miR-196a, whereas the protein expression level of HMGA2 was inhibited by miR-204. Furthermore, the miR-196a inhibitor blocked cell proliferation. Our results indicate that the combined expression signatures of miR-375, miR-204 and miR-196a are promising biomarkers for the diagnosis, prognosis and treatment of OSCC.

Investigation of the association between miR‑181b, Bcl‑2 and LRIG1 in oral verrucous carcinoma

Abnormal expression of microRNAs (miRNAs) is involved in the development of and anti-apoptotic effects in various types of human cancer. However, miRNA-mediated regulation of oral verrucous carcinoma (OVC) remains to be elucidated. The present study aimed to investigate the expression of miR-181b in OVC and oral squamous cell carcinoma (OSCC). The expression levels of miR-181b were determined using reverse transcription-quantitative polymerase chain reaction. The expression levels of B-cell lymphoma 2 (Bcl-2) and leucine rich repeats and immunoglobulin like domains 1 (LRIG1), were evaluated using immunohistochemical staining. The correlation between Bcl-2 and LRIG1 expression was determined using a Pearson correlation analysis. The expression levels of miR-181b and Bcl-2 in OVC were significantly higher compared with normal mucosal tissue (NM); however, lower compared with the OSCC. The key target of miR-181b was LRIG1 and it was significantly lower in OVC tissues compared with NM tissue; however this was higher when compared with OSCC tissue. The expression levels of Bcl-2 were correlated with expression levels of LRIG1 in OVC tissues. Therefore, LRIG1 may be associated with anti-apoptotic function in OVC tissues.

Similar Squamous Cell Carcinoma Epithelium microRNA Expression in Never Smokers and Ever Smokers

The incidence of oral tumors in patients who never used mutagenic agents such as tobacco is increasing. In an effort to better understand these tumors we studied microRNA (miRNA) expression in tumor epithelium of never tobacco users, tumor epithelium of ever tobacco users, and nonpathological control oral epithelium. A comparison of levels among 372 miRNAs in 12 never tobacco users with oral squamous cell carcinoma (OSCC) versus 10 healthy controls was made using the reverse transcription quantitative polymerase chain reaction. A similar analysis was done with 8 ever tobacco users with OSCC. These comparisons revealed miR-10b-5p, miR-196a-5p, and miR-31-5p as enriched in the tumor epithelium in OSCC of both never and ever tobacco users. Examination of The Cancer Genome Atlas (TCGA) project miRNA data on 305 OSCCs and 30 controls revealed 100% of those miRNAs enriched in never smoker OSCCs in this patient group were also enriched in ever smoker OSCCs. Nonsupervised clustering of TCGA OSCCs was suggestive of two or four subgroups of tumors based on miRNA levels with limited evidence for differences in tobacco exposure among the groups. Results from both patient groups together stress the importance of miR196a-5p in OSCC malignancy in both never and ever smokers, and emphasize the overall similarity of miRNA expression in OSCCs in these two risk groups. It implies that there may be great similarity in etiology of OSCC in never and ever smokers and that classifying OSCC based on tobacco exposure may not be helpful in the clinic.

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.

Non-coding RNAs deregulation in oral squamous cell carcinoma: advances and challenges

Oral squamous cell carcinoma (OSCC) is a common cause of cancer death. Despite decades of improvements in exploring new treatments and considerable advance in multimodality treatment, satisfactory curative rates have not yet been reached. The difficulty of early diagnosis and the high prevalence of metastasis associated with OSCC contribute to its dismal prognosis. In the last few decades the emerging data from both tumor biology and clinical trials led to growing interest in the research for predictive biomarkers. Non-coding RNAs (ncRNAs) are promising biomarkers. Among numerous kinds of ncRNAs, short ncRNAs, such as microRNAs (miRNAs), have been extensively investigated with regard to their biogenesis, function, and importance in carcinogenesis. In contrast to miRNAs, long non-coding RNAs (lncRNAs) are much less known concerning their functions in human cancers especially in OSCC. The present review highlighted the roles of miRNAs and newly discovered lncRNAs in oral tumorigenesis, metastasis, and their clinical implication.

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.

Expression and clinical significance of microRNA-1246 in human oral squamous cell carcinoma

BACKGROUND

MicroRNAs (miRNAs) are small, non-coding RNAs that may function as oncogenes or tumor suppressors. Previous studies have shown that the expression level of miR-1246 was enhanced in multiple types of cancers. However, the expression of miR-1246 in human oral squamous cell carcinoma (OSCC) and its prognostic values remain unclear.

MATERIAL AND METHODS

Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) was used to analyze the expression of miR-1246 in 106 pairs of matched normal and tumor tissue samples. The chi-square test was used to examine the associations between miR-1246 expression and the clinicopathological characters. The survival curves were constructed by the Kaplan-Meier method. The influence of each clinical variable on survival was examined by the Cox multivariate regression analysis.

RESULTS

The expression level of miR-1246 was significantly higher in tumor tissues and oral cancer cell lines than in normal controls (p<0.01). High expression of miR-1246 was found to significantly correlate with nodal status (p=0.015), TNM stage (p=0.005), and tumor grade (p=0.002). Enhanced miR-1246 correlated significantly with patient survival (p<0.01). In multivariate analysis, we found that miR-1246 expression was an independent prognostic factor of poor patient survival (p= 0.036; HR=2.82; 95% CI=1.07-7.43).

CONCLUSIONS

High miR-1246 expression is associated with poor prognosis in OSCC and may serve as a novel prognostic marker in OSCC.

miR-494 represses HOXA10 expression and inhibits cell proliferation in oral cancer

OBJECTIVES

miR-494 was identified as a candidate of the most significantly underexpressed microRNAs (miRNAs) in our oral cancer screen. The aim of this study was to validate whether miR-494 has a functional role in oral cancer.

METHODS

Quantitative miRNA analyses were performed on oral tumor RNA and oral cancer cell lines. HOXA10 was selected for further analysis based on bioinformatics analysis of miR-494 targets and a previous report of overexpression of HOXA10 in oral cancer. Transient transfection of miRNA-mimic and inhibitor were performed in SCC-25 (tongue), CAL 27 (tongue), and FaDu (pharynx) cancer cells and regulation of HOXA10 by miR-494 was investigated. Dual luciferase assay was used to verify the interaction between miR-494 and HOXA10 in reporter cells. The effect of miR-494 on cell proliferation was examined.

RESULTS

Our data showed that miR-494 was underexpressed whereas HOXA10 was overexpressed in oral cancer compared to normal tissues. An inverse correlation between miR-494 and HOXA10 was observed in the human tissues (p<0.05). Transient transfection of miR-494 in all cancer cell lines significantly reduced the expression of HOXA10 mRNA. The luciferase reporter that contains the 3'UTR of HOXA10 showed a significantly reduced luciferase activity by miR-494 indicating a direct interaction between HOXA10 and miR-494. Significant reduction in cell proliferation was demonstrated in tongue cancer cells transfected with miR-494.

CONCLUSION

miR-494 repressed the expression of HOXA10 and also reduced the proliferation of oral cancer cells. These data give more evidence of the role of miR-494 as a tumor suppressor miRNA in oral cancer.

MicroRNA-29b regulates migration in oral squamous cell carcinoma and its clinical significance

OBJECTIVES

MicroRNA (miRNA) machinery regulates cancer cell behavior, and has been implicated in patients' clinical status and prognosis. We found that microRNA-29b (miR-29b) increased significantly in advanced migratory cells. However, miR-29b controls the migration ability, and its regulatory mechanism in oral squamous cell carcinoma (OSCC) remains unknown.

MATERIALS AND METHODS

We triggered miR-29b expression in OSCC patients and cell lines by conducting real-time quantitative PCR. We determined the functions of miR-29b in the migration of OSCC cells by using gain- and loss-of-function approaches. We elevated the target genes of miR29b through software predictions and a luciferase report assay. We used an orthotopic OSCC animal model to investigate the effects of miR29b on OSCC cell metastasis in vivo.

RESULTS

The clinical data revealed that miR-29b expression was correlated with lymph node metastasis and an advanced tumor stage in 98 OSCC patients. Furthermore, multivariate analysis revealed that miR-29b expression was significantly correlated with recurrence, and indicated poor survival. MiR-29b promoted OSCC cell migration and downregulated CX3CL1, a cell-cell adhesion regulator, which plays an essential role in miR-29b-regulated OSCC cell migration machinery. Furthermore, we found that CX3CL1 expression was correlated with lymph node metastasis and an early tumor stage in OSCC patients, and negatively correlated with miR-29b expression.

CONCLUSION

MiR-29b acts as an oncomir, promoting cell migration through CX3CL1 suppression, and could be a potential therapeutic target for preventing OSCC progression.

Identification and characterization of Dicer1e, a Dicer1 protein variant, in oral cancer cells

Background

The human dicer1 gene has been predicted to produce several mRNA variants that encode truncated Dicer1 proteins of varying lengths. One of these Dicer1 variants, Dicer1e, was recently found to be differentially expressed in breast cancer cells. Because the expression and function of the Dicer1e protein variant has not been well characterized and the underlying molecular mechanisms for the development of oral squamous cell carcinomas (OSCCs) are poorly understood, the present study sought to characterize the biological role of Dicer1e and determine its relationship, if any, to OSCC pathogenesis.

Methods

Western blot analyses were used to examine Dicer1e expression levels in a panel of oral cancer cells/tissues and during epithelial-mesenchymal transition (EMT), followed by 5′/3′-RACE analyses to obtain the full-length Dicer1e transcript. Biochemical fractionation and indirect immunofluorescent studies were performed to determine the cellular localization of Dicer1e and the effects of Dicer1e silencing on cancer cell proliferation, clonogenicity, and drug sensitivity were also assessed.

Results

Dicer1e protein levels were found to be overexpressed in OSCC cell lines of epithelial phenotype and in OSCC tissues with its levels downregulated during EMT. Moreover, the Dicer1e protein was observed to predominantly localize in the nucleus. 5′/3′-RACE analyses confirmed the presence of the Dicer1e transcript and silencing of Dicer1e impaired both cancer cell proliferation and clonogenicity by inducing either apoptosis and/or G2/M cell cycle arrest. Lastly, Dicer1e knockdown enhanced the chemosensitivity of oral cancer cells to cisplatin.

Conclusion

The expression levels of Dicer1e influence the pathogenesis of oral cancer cells and alter their response to chemosensitivity, thus supporting the importance of Dicer1e as a therapeutic target for OSCCs.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-190) contains supplementary material, which is available to authorized users.