MicroRNA expression as predictor of local recurrence risk in oral squamous cell carcinoma

miR-136-5p: A key player in human cancers with diagnostic, prognostic and therapeutic implications

MiRNAs have emerged as crucial modulators of the expression of their target genes, attracting significant attention due to their engagement in various cellular processes, like cancer onset and development. Amidst the extensive repertoire of miRNAs implicated in cancer, miR-136-5p has emerged as an emerging miRNA with diverse roles. Dysregulation of miR-136-5p has been proved in human cancers. Accumulating evidence suggests that miR-136-5p mainly functions as a tumor suppressor. These data proposed that miR-136-5p is engaged in the regulation of various cellular processes, like cell proliferation, migration, invasion, EMT, and apoptosis. In addition, miR-136-5p has demonstrated substantial potential as a prognostic and diagnostic marker in human cancers as well as an effective mediator in cancer chemotherapy. Furthermore, miR-136-5p was shown to be correlated with clinicopathological features of affected patients, proposing that it could be used for cancer staging and patient survival. Therefore, a comprehensive comprehension of the precise molecular basis governing miR-136-5p dysregulation in different cancers is vital for unraveling its therapeutic importance. Here, we have discussed the molecular basis of miR-136-5p as a potential tumor suppressor as well as its importance in cancer diagnosis, prognosis, and chemotherapy. Finally, we have discussed the challenge of using miRNAs as a therapeutic target as well as the prospect regarding the importance of miR-136-5p in human cancers.

The Potential microRNA Prognostic Signature in HNSCCs: A Systematic Review

Head and neck squamous cell carcinomas (HNSCCs) are often diagnosed at advanced stages, incurring significant high mortality and morbidity. Several microRNAs (miRs) have been identified as pivotal players in the onset and advancement of HNSCCs, operating as either oncogenes or tumor suppressors. Distinctive miR patterns identified in tumor samples, as well as in serum, plasma, or saliva, from patients have significant clinical potential for use in the diagnosis and prognosis of HNSCCs and as potential therapeutic targets. The aim of this study was to identify previous systematic reviews with meta-analysis data and clinical trials that showed the most promising miRs in HNSCCs, enclosing them into a biomolecular signature to test the prognostic value on a cohort of HNSCC patients according to The Cancer Genome Atlas (TCGA). Three electronic databases (PubMed, Scopus, and Science Direct) and one registry (the Cochrane Library) were investigated, and a combination of keywords such as "signature microRNA OR miR" AND "HNSCC OR LSCC OR OSCC OR oral cancer" were searched. In total, 15 systematic literature reviews and 76 prognostic clinical reports were identified for the study design and inclusion process. All survival index data were extracted, and the three miRs (miR-21, miR-155, and miR-375) most investigated and presenting the largest number of patients included in the studies were selected in a molecular biosignature. The difference between high and low tissue expression levels of miR-21, miR-155, and miR-375 for OS had an HR = 1.28, with 95% CI: [0.95, 1.72]. In conclusion, the current evidence suggests that miRNAs have potential prognostic value to serve as screening tools for clinical practice in HNSCC follow-up and treatment. Further large-scale cohort studies focusing on these miRNAs are recommended to verify the clinical utility of these markers individually and/or in combination.

Tumor-Suppressive and Immunomodulating Activity of miR-30a-3p and miR-30e-3p in HNSCC Cells and Tumoroids

Head and neck squamous cell carcinomas (HNSCCs) are heterogeneous tumors, well known for their frequent relapsing nature. To counter recurrence, biomarkers for early diagnosis, prognosis, or treatment response prediction are urgently needed. miRNAs can profoundly impact normal physiology and enhance oncogenesis. Among all of the miRNAs, the miR-30 family is frequently downregulated in HNSCC. Here, we determined how levels of the 3p passenger strands of miR-30a and miR-30e affect tumor behavior and clarified their functional role in LA-HNSCC. In a retrospective study, levels of miR-30a-3p and miR-30e-3p were determined in 110 patients and correlated to overall survival, locoregional relapse, and distant metastasis. miR-30a/e-3p were expressed in HNSCC cell lines and HNSCC patient-derived tumoroids (PDTs) to investigate their effect on tumor cells and their microenvironment. Both miRNAs were found to have a prognosis value since low miR-30a/e-3p expression correlates to adverse prognosis and reduces overall survival. Low expression of miR-30a/e-3p is associated with a shorter time until locoregional relapse and a shorter time until metastasis, respectively. miR-30a/e-3p expression downregulates both TGF-βR1 and BMPR2 and attenuates the survival and motility of HNSCC. Results were confirmed in PDTs. Finally, secretomes of miR-30a/e-3p-transfected HNSCC activate M1-type macrophages, which exert stronger phagocytic activities toward tumor cells. miR-30a/e-3p expression can discriminate subgroups of LA-HNSCC patients with different prognosis, making them good candidates as prognostic biomarkers. Furthermore, by targeting members of the TGF-β family and generating an immune-permissive microenvironment, they may emerge as an alternative to anti-TGF-β drugs to use in combination with immune checkpoint inhibitors.

A novel panel of clinically relevant miRNAs signature accurately differentiates oral cancer from normal mucosa

INTRODUCTION

Although a considerable body of knowledge has been accumulated regarding the early diagnosis and treatment of oral squamous cell carcinoma (OSCC), its survival rates have not improved over the last decades. Thus, deciphering the molecular mechanisms governing oral cancer will support the development of even better diagnostic and therapeutic strategies. Previous studies have linked aberrantly expressed microRNAs (miRNAs) with the development of OSCC.

METHODS

We combined bioinformatical and molecular methods to identify miRNAs with possible clinical significance as biomarkers in OSCC. A set of 10 miRNAs were selected via an in silico approach by analysing the 3'untranslated regions (3'UTRs) of cancer-related mRNAs such as FLRT2, NTRK3, and SLC8A1, TFCP2L1 and etc. RT-qPCR was used to compare the expression of in silico identified miRNAs in OSCC and normal tissues (n=32).

RESULTS

Among the screened miRNAs, miR-21-5p (p < 0.0001), miR-93-5p (p < 0.0197), miR-146b-5p (p <0.0012), miR-155-5p (p < 0.0001), miR-182-5p (p < 0.0001) were significantly overexpressed, whereas miR-133b (p < 0.05) was significantly downregulated in OSCC tissues, a scenario confirmed in two additional OSCC validation cohorts: Regina Elena National Cancer Institute (IRE cohort, N=74) and The Cancer Genome Atlas Data Portal (TCGA cohort, N=354). Initial stage tumors (T1, T2) expressed significantly higher levels of miR-133b (p < 0.0004) compared to more advanced ones (T3, T4). Also, we identified miR-93-5p (p < 0.0003), miR-133b (p < 0.0017) and miR-155-5p (p < 0.0004) as correlated with HPV-induced OSCC. The high expression of these 6 miRNAs as a signature predicted shorter disease-free survival (DFS) and could efficiently distinguish OSCC cases from healthy controls with areas under the curve (AUC) of 0.91 with sensitivity and specificity of 0.98 and 0.6, respectively. Further target identification analysis revealed enrichment of genes involved in FOXO, longevity, glycan biosynthesis and p53 cancer-related signaling pathways. Also, the selected targets were underexpressed in OSCC tissues and showed clinical significance related to overall survival (OS) and DFS.

DISCUSSION

Our results demonstrate that a novel panel consisting of miR-21-5p, miR-93-5p, miR-133b, miR-146b-5p, miR-155-5p and miR-182-5p could be used as OSCC-specific molecular signature with diagnostic and prognostic significance related to OS and DFS.

CircCSDE1 Regulates Proliferation and Differentiation of C2C12 Myoblasts by Sponging miR-21-3p

The growth and development of skeletal muscle is regulated by many factors, and recent studies have shown that circular RNAs (circRNAs) can participate in this process. The model of porcine skeletal muscle injury was constructed to search for circRNAs that can regulate the growth and development of skeletal muscle in pigs. Using whole-transcriptome sequencing and bioinformatics analysis, a novel circRNA (circCSDE1) was screened out, which is highly expressed in skeletal muscle. Functional studies in C2C12 cells demonstrated that circCSDE1 could promote proliferation and inhibit myoblast differentiation, while opposing changes were observed by circCSDE1 knockdown. A dual-luciferase reporter assay revealed that circCSDE1 directly targeted miR-21-3p to regulate the expression of the downstream target gene (Cyclin-dependent kinase 16, CDK16). Moreover, miR-21-3p could inhibit proliferation and promote myoblast differentiation in C2C12 cells, opposite with the effects of circCSDE1. Additionally, the rescue experiments offered further evidence that circCSDE1 and its target, miR-21-3p, work together to regulate myoblast proliferation and differentiation. This study provides a theoretical basis for further understanding the regulatory mechanisms of circRNAs.

Liquid Biopsy in Squamous Cell Carcinoma of the Esophagus and of the Head and Neck

Squamous cell carcinomas of the esophagus (ESCC) and of the head and neck (HNSCC) are two neoplasms that share common risk factors and have the same embryological origin, but a very different prognosis, the 5-year survival of HNSCC being almost double (40–50%) compared to the 5-year survival of ESCC (20%). Current guidelines emphasize the importance of screening for ESCC in patients diagnosed with head and neck cancers. A liquid biopsy is a novel tool for diagnosis, prognostic stratification, and personalized therapy. Liquid biopsy biomarkers for these two malignancies could help both their early detection, facilitate residual disease identification, and provide prognosis information. The present systematic review of the literature was aimed at describing the liquid biopsy biomarkers present in these two malignancies, with an emphasis on potential clinical applications.

MicroRNA-21 Expression as a Prognostic Biomarker in Oral Cancer: Systematic Review and Meta-Analysis

Oral carcinoma represents one of the main carcinomas of the head and neck region, with a 5-year survival rate of less than 50%. Smoking and tobacco use are recognized risk factors. Prognostic survival biomarkers can be a valid tool for assessing a patient’s life expectancy and directing therapy towards specific targets. Among the biomarkers, the alteration of miR-21 expression in tumor tissues is increasingly reported as a valid prognostic biomarker of survival for oral cancer. The purpose of this meta-analysis was, therefore, to investigate and summarize the results in the literature concerning the potential prognostic expression of tissue miR-21 in patients with OSCC. Methods: The systematic review was conducted following the PRISMA guidelines using electronic databases, such as PubMed, Scopus, and the Cochrane Central Register of Controlled Trials, with the use of combinations of keywords, such as miR-21 AND oral cancer, microRNA AND oral cancer, and miR-21. The meta-analysis was performed using the RevMan 5.41 software. Results: At the end of the article-selection process, 10 studies were included in the meta-analysis, and the result for the main outcome was a pooled HR per overall survival (OS) of 1.29 (1.16–1.44) between high and low expression of miR-21. Conclusions: The data in the literature and the results emerging from the systematic review indicate that miR-21 can provide a prognostic indication in oral cancer.

The meta-signature guided investigation of miRNA candidates as potential biomarkers of oral cancer

OBJECTIVES

This study aimed to experimentally validate dysregulated expression of miRNA candidates selected through updated meta-analysis of most commonly deregulated miRNAs in oral cancer and to explore their diagnostic and prognostic potential.

MATERIALS AND METHODS

Five miRNAs (miR-31-3p, miR-135b-5p, miR-18a-5p, miR-30a-5p, miR-139-5p) from updated meta-signature were selected for validation by qRT-PCR method in 35 oral cancer clinical specimens and adjacent non-cancerous tissue.

RESULTS

Updated meta-analysis has identified 13 most commonly deregulated miRNAs in oral cancer. Seven miRNAs were consistently up-regulated (miR-21-5p, miR-31-3p, miR-135b-5p, miR-31-5p, miR-424-5p, miR-18a-5p, miR-21-3p), while five were down-regulated (miR-139-5p, miR-30a-3p, miR-375-3p, miR-376c-3p, miR-30a-5p). Increased expression of miR-31-3p, miR-135b-5p, as well as decreased expression of miR-139-5p and miR-30a-5p were confirmed in oral cancer compared to adjacent non-cancerous tissue. A three-miRNAs combination (miR-31-3p, miR-139-5p, miR-30a-5p) gave the most promising diagnostic potential for discriminating oral cancer from non-cancerous tissue (AUC: 0.780 (95% CI: 0.673-0.886), p<0.0005, sensitivity 94.3%, specificity 51.4%). High expression of miR-135b-5p, miR-18a-5p and miR-30a-5p was associated with poor survival (p=0.003, p=0.048, p=0.016, respectively).

CONCLUSION

miR-31-3p, miR-139-5p, miR-30a-5p panel was confirmed as a potential diagnostic biomarker when distinguishing oral cancer from non-cancerous tissue. miR-135b-5p, miR-18a-5p and miR-30a-5p might serve as potential biomarkers of poor survival of oral cancer patients.

Expression of hsv1-miR-H18 and hsv2-miR-H9 as a field defect marker for detecting prostate cancer

Background

Prostate-specific antigen (PSA) is a marker of prostate cancer (PCa), although its efficacy as a diagnostic marker remains controversial. A high false-positive rate leads to repeat biopsy in approximately 70% of patients, which may not be necessary. Epigenetic biomarkers of field cancerization have been investigated widely as promising tools for the diagnosis of patients with suspected tumors. In the current study, we examined the diagnostic value of two microRNA (miRNA) candidates, hsv1-miR-H18 and hsv2-miR-H9, using formalin-fixed paraffin-embedded (FFPE) tissues from patients with PCa or benign prostate hyperplasia (BPH) (as controls) to determine the usefulness of these markers for detecting the presence of cancer.

Methods

Expression of hsv1-miR-H18 and hsv2-miR-H9 in 201 FFPE tissues, including 52 primary tumors, 73 surrounding noncancerous tissues, and 90 BPH nontumor controls was examined by real-time PCR.

Results

Expression of hsv1-miR-H18 and hsv2-miR-H9 was significantly higher in primary tumors from PCa patients than in BPH controls (P < 0.0001). In patients within the PSA gray zone, the two viral miRNAs could distinguish PCa from controls with appropriate sensitivity and specificity. Expression of the two miRNAs did not differ between primary tumors and noncancerous surrounding tissues.

Conclusions

The viral miRNAs hsv1-miR-H18 and hsv2-miR-H9 may be associated with field cancerization of PCa and could be promising supplemental biomarkers to the PSA assay to decrease the rate of unnecessary biopsy, particularly in patients within the PSA gray zone.

Salivary miR-31-5p, miR-345-3p, and miR-424-3p Are Reliable Biomarkers in Patients with Oral Squamous Cell Carcinoma

If not detected early, oral squamous cell carcinoma (OSCC) has very poor prognosis, emphasizing the need for reliable early diagnostics. Saliva is considered a promising surrogate biosample for OSCC detection, because it comes into contact with many cells of the tumor mass, providing a comprehensive sampling of tumor-specific biomolecules. Although several protein- and RNA-based salivary biomarkers have been proposed for the detection of OSCC, the results of the studies show large differences. Our goal was to clarify which salivary microRNAs (miRNA) show reliably high expression in the saliva of OSCC patients, to be used as cancer-specific biomarkers, and potentially as early diagnostic biomarkers. Based on a detailed literature search, we selected six miRNAs commonly overexpressed in OSCC, and analyzed their expression in saliva samples of cancer patients and controls by real-time quantitative PCR. Our results suggest that miR-345 and miR-31-5p are consistently upregulated salivary biomarkers for OSCC, and a three-miRNA panel of miR-345, miR-31-5p, and miR-424-3p can distinguish cancer and control patients with high sensitivity.

Multiple microRNA signature panel as promising potential for diagnosis and prognosis of head and neck cancer

MicroRNAs are small non-coding RNA that regulate gene expressions of human body. To date, numerous studies have reported that microRNAs possess great diagnostic and prognostic power in head and neck cancer and had governed a lot of attention. The factor for the successfulness of miRNAs in these aspects is due to cancer being fundamentally tied to genetic changes, which are regulated by these miRNAs. Head and neck cancer, leading the world record for cancer as number sixth, is caused by multiple risk factors such as tobacco consumption, alcohol consumption, dietary factors, ethnicity, family history, and human papilloma virus. It derives at locations such as oral cavity, pharynx, larynx, paranasal sinus and salivary gland and have high rate of mortality with high recurrence rate. Besides, head and neck cancer is also usually having poor prognosis due to its asymptomatic nature. However, this diagnostic and prognostic power can be further improved by using multiple panels of miRNA as a signature or even combined with TNM staging system to obtain even more remarkable results. This is due to multiple factors such as tumour heterogeneity and components of the tumour which may affect the composition of miRNAs. This review covers the examples of such miRNA signatures, compare their diagnostic and prognostic powers, discuss some controversial roles of unreported miRNAs, and the molecular mechanisms of the miRNAs in gene targeting and pathways.

Diagnostic and Prognostic Value of MicroRNAs in Metastasis and Recurrence of Head and Neck Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

MicroRNAs have been proven to make remarkable differences in the clinical behaviors of head and neck squamous cell carcinoma (HNSCC). This study aims to systematically analyze whether differential expression levels of microRNAs are related to recurrence or metastasis in patients with HNSCC. A comprehensive search of the PubMed, EMBASE, and CENTRAL was conducted up to July 24^th, 2021. Data were collected and combined from studies reporting recurrence-free survival (RFS) of HNSCC patients with high microRNA expression compared to those with low expression. Besides, studies providing necessary data for evaluating the diagnostic value of microRNAs for detecting recurrence and metastasis based on their expression levels were also included and combined. The pooled hazard ratio (HR) value for the outcomes of RFS in 1,093 HNSCC samples from 10 studies was 2.51 (95%CI: 2.13–2.96). A sensitivity of 0.79 (95% CI: 0.72–0.85) and specificity of 0.77 (95%CI: 0.68–0.83) were observed in three studies, of which 93 patients with recurrence and 82 nonrecurrence controls were included, and the area under the curve (AUC) was 0.85 (95% CI: 0.81–0.88). Additionally, high diagnostic accuracy of microRNAs in detecting lymph node metastasis (LNM) was also reported. In conclusion, two panels of microRNAs showed the potential to predict recurrence or diagnose recurrence in HNSCC patients, respectively, which could facilitate prognosis prediction and diagnosis of clinical behaviors in HNSCC patients.

MicroRNA-182-5p and microRNA-205-5p as potential biomarkers for prognostic stratification of p16-positive oropharyngeal squamous cell carcinoma

BACKGROUND

MicroRNAs constitute promising biomarkers.

OBJECTIVE

The aim was to investigate diagnostic and prognostic implications of miR-182-5p and miR-205-5p in p16-positive and p16-negative oropharyngeal squamous cell carcinomas (OPSCCs).

METHODS

Expression of miR-182-5p, miR-205-5p were determined via quantitative real-time-PCR in fresh frozen tissues of 26 p16-positive, 19 p16-negative OPSCCs and 18 HPV-negative oropharyngeal controls. Associations between miRNA-expression, clinicopathological characteristics and prognosis were analyzed.

RESULTS

Higher miR-182-5p expression was associated with significant inferior disease-specific survival for p16-positive OPSCCs (HR = 1.98E+09, 95% CI 0-Inf; P= 0.028) and a similar trend was observed for p16-negative OPSCCs (HR = 1.56E+09, 95% CI 0-Inf; P= 0.051). Higher miR-205-5p expression was associated with an inferior progression-free survival (HR = 4.62, 95% CI 0.98-21.83; P= 0.034) and local control rate (HR = 2.18E+09, 95% CI 0-Inf; P= 0.048) for p16-positive OPSCCs.

CONCLUSIONS

Results indicate that miR-182-5p and miR-205-5p can further stratify patients with p16-positive OPSCC into prognostic groups.

MicroRNAs in head and neck squamous cell carcinoma: a possible challenge as biomarkers, determinants for the choice of therapy and targets for personalized molecular therapies

Head and neck squamous cell carcinoma (HNSCC) are referred to a group of heterogeneous cancers that include structures of aerodigestive tract such as oral and nasal cavity, salivary glands, oropharynx, pharynx, larynx, paranasal sinuses, and local lymph nodes. HNSCC is characterized by frequent alterations of several genes such as TP53, PIK3CA, CDKN2A, NOTCH1, and MET as well as copy number increase in EGFR, CCND1, and PIK3CA. These genomic alterations play a role in terms of resistance to chemotherapy, molecular targeted therapy, and prediction of patient outcome. MicroRNAs (miRNAs) are small single-stranded noncoding RNAs which are about 19-25 nucleotides. They are involved in the tumorigenesis of HNSCC including dysregulation of cell survival, proliferation, cellular differentiation, adhesion, and invasion. The discovery of the stable presence of the miRNAs in all human body made them attractive biomarkers for diagnosis and prognosis or as targets for novel therapeutic ways, enabling personalized treatment for HNSCC. In recent times the number of papers concerning the characterization of miRNAs in the HNSCC tumorigenesis has grown a lot. In this review, we discuss the very recent studies on different aspects of miRNA dysregulation with their clinical significance and we apologize for the many past and most recent works that have not been mentioned. We also discuss miRNA-based therapy that are being tested on patients by clinical trials.

Roles of microRNAs in Regulating Cancer Stemness in Head and Neck Cancers

Head and neck squamous cell carcinomas (HNSCCs) are epithelial malignancies with 5-year overall survival rates of approximately 40-50%. Emerging evidence indicates that a small population of cells in HNSCC patients, named cancer stem cells (CSCs), play vital roles in the processes of tumor initiation, progression, metastasis, immune evasion, chemo-/radioresistance, and recurrence. The acquisition of stem-like properties of cancer cells further provides cellular plasticity for stress adaptation and contributes to therapeutic resistance, resulting in a worse clinical outcome. Thus, targeting cancer stemness is fundamental for cancer treatment. MicroRNAs (miRNAs) are known to regulate stem cell features in the development and tissue regeneration through a miRNA-target interactive network. In HNSCCs, miRNAs act as tumor suppressors and/or oncogenes to modulate cancer stemness and therapeutic efficacy by regulating the CSC-specific tumor microenvironment (TME) and signaling pathways, such as epithelial-to-mesenchymal transition (EMT), Wnt/β-catenin signaling, and epidermal growth factor receptor (EGFR) or insulin-like growth factor 1 receptor (IGF1R) signaling pathways. Owing to a deeper understanding of disease-relevant miRNAs and advances in in vivo delivery systems, the administration of miRNA-based therapeutics is feasible and safe in humans, with encouraging efficacy results in early-phase clinical trials. In this review, we summarize the present findings to better understand the mechanical actions of miRNAs in maintaining CSCs and acquiring the stem-like features of cancer cells during HNSCC pathogenesis.

MicroRNAs as Modulators of Oral Tumorigenesis-A Focused Review

Oral cancers constitute the majority of head and neck tumors, with a relatively high incidence and poor survival rate in developing countries. While the five-year survival rates of the oral cancer patients have increased to 65%, the overall survival for advanced stages has been at 27% for the past ten years, emphasizing the necessity for further understanding the etiology of the disease, diagnosis, and formulating possible novel treatment regimens. MicroRNAs (miRNAs), a family of small non-coding RNA, have emerged as master modulators of gene expression in various cellular and biological process. Aberrant expression of these dynamic molecules has been associated with many human diseases, including oral cancers. The deregulated miRNAs have been shown to control various oncogenic processes, including sustaining proliferative signaling, evading growth suppressors, resisting cell death activating invasion and metastasis, and inducing angiogenesis. Hence, the aberrant expression of miRNAs associated with oral cancers, makes them potential candidates for the investigation of functional markers, which will aid in the differential diagnosis, prognosis, and development of novel therapeutic regimens. This review presents a holistic insight into our understanding of the role of miRNAs in regulating various hallmarks of oral tumorigenesis.

MicroRNAs in oral cancer: Biomarkers with clinical potential

Oral cancer is the sixteenth most common cancer globally, with a relatively poor five-year survival rate of 50%. Thus it is imperative to understand the biology of oral cancer and examine alternative prognostic and therapeutic targets for oral cancer. MicroRNAs (miRNAs) are small non-coding RNAs mediating gene expression at the post-transcriptional level through mRNA degradation or translational repression. miRNAs play an essential role in cancer development and oncogenic cell processes. miRNA deregulation is observed in oral cancer and associated with prognosis. However, the role of miRNAs and their clinical implications in oral cancer is not clear. The current review highlights the miRNA profile of oral cancer and discusses the diagnostic, prognostic and potential therapeutic targets with clinical implications. miRNAs mediate activation or suppression of signalling pathways associated with oral cancer. Hence, a panel of select deregulated miRNAs may indicate clinicopathological features, personalised treatment outcome and provide novel lead profiles of oral cancer. The translational applications of miRNAs may lead to better management and survival of oral cancer patients. The compiled data provides a platform for consideration of miRNA signatures as potential biomarkers for early oral cancer diagnosis, prognosis and as novel molecular therapies.

CircRNAs: A New Chapter in Oral Squamous Cell Carcinoma Biology

With the rapid development of bioinformatics and gene sequencing technologies, understanding of circular RNAs (circRNAs) has been extended, and numerous studies have identified the key regulator role of circRNAs in a variety of diseases, especially in cancer. Recently, accumulated studies of oral squamous cell carcinoma (OSCC) have discovered the great potential of circRNAs, which can serve as prognostic or diagnostic biomarkers and affect the development and therapy of OSCC. In this review, we detail the new progress of circRNA research for OSCC in order to provide new strategies for clinical diagnosis and treatment.

microRNAs in oral cancer: Moving from bench to bed as next generation medicine

Oral cancer is the thirteenth most common cancer in the world, with India contributing to 33% of the global burden. Lack of specific non-invasive markers, non-improvement in patient survival and tumor recurrence remain a major clinical challenge in oral cancer. Epigenetic regulation in the form of microRNAs (miRs) that act as tumor suppressor miRs or oncomiRs has gained significant momentum with the advancement in the field, suggesting the potential for clinical application of miRs in oral cancer. The current review of literature identified miR-21, miR-27a(-3p), miR-31, miR-93, miR-134, miR-146, miR-155, miR-196a, miR-196b, miR-211, miR-218, miR-222, miR-372 and miR-373 to be up-regulated and let-7a, let-7b, let-7c, let-7d, let-7e, let-7f, let-7g, let-7i, miR-26a, miR-99a-5p, miR-137, miR-139-5p, miR-143-3p, miR-184 and miR-375 to be down-regulated in oral cancer. Mechanistic studies have uncovered several miRs that are deregulated at varying levels and in different stages of oral cancer progression, thus providing clinical utility in better diagnosis as well as usefulness in prognosis by identifying patients with poor prognosis or stratifying patients based on responsiveness to chemo- and radio-therapy. Lastly, exogenous modulation of miR expression using miRNA-based drugs in combination with first-line agents may be adopted as a new therapeutic modality to treat oral cancer. Knowledge of miRs and their involvement in key molecular processes, clinical association, responsiveness to therapy and clinical advancement may highlight additional avenues in order to improve patient morbidity and mortality. Furthermore, combinatorial approaches with miR-therapy may be efficacious in oral cancer.

miR-96-5p targets PTEN expression affecting radio-chemosensitivity of HNSCC cells

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is the sixth leading cancer worldwide. They are typically characterized by a high incidence of local recurrence, which is the most common cause of death in HNSCC patients. TP53 is the most frequently mutated gene in HNSCC and patients carrying TP53 mutations are associated with a higher probability to develop local recurrence. MiRNAs, which are among the mediators of the oncogenic activity of mt-p53 protein, emerge as an appealing tool for screening, diagnosis and prognosis of cancer. We previously identified a signature of 12 miRNAs whose aberrant expression associated with TP53 mutations and was prognostic for HNSCC. Among them miR-96-5p emerges as an oncogenic miRNAs with prognostic significance in HNSCC.

METHODS

To evaluate the oncogenic role of miR-96-5p in a tumoral context, we performed colony formation, cell migration and cell viability assays in two HNSCC cell lines transfected for miR-96-5p mimic or inhibitor and treated with or without radio/chemo-therapy. In addition, to identify genes positively and negatively correlated to miR-96-5p expression in HNSCC, we analyzed the correlation between gene expression and miR-96-5p level in the subset of TCGA HNSCC tumors carrying missense TP53 mutations by Spearman and Pearson correlation. To finally identify targets of miR-96-5p, we used in silico analysis and the luciferase reporter assay to confirm PTEN as direct target.

RESULTS

Our data showed that overexpression of miR-96-5p led to increased cell migration and radio-resistance, chemotherapy resistance in HNSCC cells. In agreement with these results, among the most statistically significant pathways in which miR-96-5p is involved, are focal Adhesion, extracellular matrix organization and PI3K-Akt-mTOR-signaling pathway. As a direct target of miR-96-5p, we identified PTEN, the main negative regulator of PI3K-Akt signalling pathway activation.

CONCLUSIONS

These results highlight a new mechanism of chemo/radio-resistance insurgence in HNSCC cells and support the possibility that miR-96-5p expression could be used as a novel promising biomarker to predict radiotherapy response and local recurrence development in HNSCC patients. In addition, the identification of pathways in which miR-96-5p is involved could contribute to develop new therapeutic strategies to overcome radio-resistance.

Circular RNAs and their roles in head and neck cancers

Circular RNAs are abundant endogenous non-coding RNA with no 5′ cap and 3′ polyadenylation tail that modify liner mRNAs and have no terminal structures. Our knowledge of the biogenesis of circular RNAs has been expanded, and circular RNAs were shown to be key regulators of various diseases, especially cancers. Head and neck cancers are the sixth most popular cancers worldwide, and the overall survival rates remain unsatisfactory. Recent studies have indicated that circular RNAs are involved in the tumorigenesis, progression, invasion and chemosensitivity of head and neck cancers and that some circular RNAs could serve as diagnostic and prognostic biomarkers. In this study, we summarize research advances in the regulation of circular RNA biogenesis, their characteristics and functions, the involvement of circular RNAs in the pathophysiology of head and neck cancers and their potential clinical utilization, as well as the likely directions of future studies.

The Role of MicroRNAs in Recurrence and Metastasis of Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) affects 650,000 people worldwide and has a dismal 50% 5-year survival rate. Recurrence and metastasis are believed the two most important factors causing this high mortality. Understanding the biological process and the underlying mechanisms of recurrence and metastasis is critical to develop novel and effective treatment, which is expected to improve patients’ survival of HNSCC. MicroRNAs are small, non-coding nucleotides that regulate gene expression at the transcriptional and post-transcriptional level. Oncogenic and tumor-suppressive microRNAs have shown to regulate nearly every step of recurrence and metastasis, ranging from migration and invasion, epithelial-mesenchymal transition (EMT), anoikis, to gain of cancer stem cell property. This review encompasses an overview of microRNAs involved in these processes. The recent advances of utilizing microRNA as biomarkers and targets for treatment, particularly on controlling recurrence and metastasis are also reviewed.

miR-125b suppresses oral oncogenicity by targeting the anti-oxidative gene PRXL2A

Oral squamous cell carcinoma (OSCC) is a globally prevalent malignancy. The molecular mechanisms of this cancer are not well understood and acquire elucidation. Peroxiredoxin like 2A (PRXL2A) has been reported to be an antioxidant protein that protects cells from oxidative stress. Our previous study identified an association between PRXL2A upregulation in OSCC and a worse patient prognosis. MicroRNAs (miRNAs) are small non-coding RNAs that are involved in the modulation of biological/pathological properties. The miR-125 family of genes drive pluripotent regulation across a wide variety of cancers. In this study, we identify the oncogenic eligibility of PRXL2A and clarify miR-125b as its upstream regulator. Downregulation of miR-125b can be observed in OSCC tumors. Lower miR-125b expression in tumors results in a worse patient prognosis at the relatively early stage. Reporter assays are able to validate that PRXL2A is a direct target of miR-125b. Exogenous miR-125b expression in OSCC cells results in increased oxidative stress, increased drug sensitivity, and suppressor activity that is paralleled by the knockout of PRXL2A gene. The suppressor activity of miR-125b is able to be rescued by PRXL2A, which suggests the existence of a miR-125b-PRXL2A regulatory axis that is part of OSCC pathogenesis. Nuclear factor-erythroid 2-related factor 2 (NRF2) was found to be a downstream effector of the miR-125b-PRXL2A cascade. As a whole, this study has pinpointed novel clues demonstrating that downregulation of miR-125b suppressor underlies upregulation of PRXL2A in OSCC, and this then protects the affected tumor cells from oxidative stress.

A Five-MicroRNA Signature Predicts Survival and Disease Control of Patients with Head and Neck Cancer Negative for HPV Infection

PURPOSE

Human papillomavirus (HPV)-negative head and neck squamous cell carcinoma (HNSCC) is associated with unfavorable prognosis, while independent prognostic markers remain to be defined.

EXPERIMENTAL DESIGN

We retrospectively performed miRNA expression profiling. Patients were operated for locally advanced HPV-negative HNSCC and had received radiochemotherapy in eight different hospitals (DKTK-ROG; n = 85). Selection fulfilled comparable demographic, treatment, and follow-up characteristics. Findings were validated in an independent single-center patient sample (LMU-KKG; n = 77). A prognostic miRNA signature was developed for freedom from recurrence and tested for other endpoints. Recursive-partitioning analysis was performed on the miRNA signature, tumor and nodal stage, and extracapsular nodal spread. Technical validation used qRT-PCR. An miRNA-mRNA target network was generated and analyzed.

RESULTS

For DKTK-ROG and LMU-KKG patients, the median follow-up was 5.1 and 5.3 years, and the 5-year freedom from recurrence rate was 63.5% and 75.3%, respectively. A five-miRNA signature (hsa-let-7g-3p, hsa-miR-6508-5p, hsa-miR-210-5p, hsa-miR-4306, and hsa-miR-7161-3p) predicted freedom from recurrence in DKTK-ROG [hazard ratio (HR) 4.42; 95% confidence interval (CI), 1.98-9.88, P < 0.001], which was confirmed in LMU-KKG (HR 4.24; 95% CI, 1.40-12.81, P = 0.005). The signature also predicted overall survival (HR 3.03; 95% CI, 1.50-6.12, P = 0.001), recurrence-free survival (HR 3.16; 95% CI, 1.65-6.04, P < 0.001), and disease-specific survival (HR 5.12; 95% CI, 1.88-13.92, P < 0.001), all confirmed in LMU-KKG data. Adjustment for relevant covariates maintained the miRNA signature predicting all endpoints. Recursive-partitioning analysis of both samples combined classified patients into low (n = 17), low-intermediate (n = 80), high-intermediate (n = 48), or high risk (n = 17) for recurrence (P < 0.001).

CONCLUSIONS

The five-miRNA signature is a strong and independent prognostic factor for disease recurrence and survival of patients with HPV-negative HNSCC.See related commentary by Clump et al., p. 1441.

miR-1246 Targets CCNG2 to Enhance Cancer Stemness and Chemoresistance in Oral Carcinomas

MiRNAs have been recognized as crucial components in carcinogenesis, but whether miR-1246 affects the cancer stemness and drug resistance in oral squamous cell carcinoma (OSCC) has not been fully understood and its downstream targets still need to be unraveled. In the present work, we employed miRNAs RT-PCR analysis to evaluate the expression of miR-1246 in tumor tissues and oral cancer stem cells (OCSC). Stemness phenotypes, including self-renewal, migration, invasion, colony formation capacities, and in vivo oncogenicity of oral cancer cells following transfected with miR-1246 inhibitors or mimics were examined. Our results suggested that the expression level of miR-1246 was significantly upregulated in the tumor tissues and OCSC. Kaplan-Meier survival analysis of OSCC patients with high levels of miR-1246 had the worst survival rate compared to their low-expression counterparts. Inhibition of miR-1246 in OCSC significantly reduced the stemness hallmarks, while overexpression of miR-1246 enhanced these characteristics. Moreover, we showed that downregulation of miR-1246 decreased chemoresistance. In addition, we verified that miR-1246-inhibited CCNG2 contributed to the cancer stemness of OSCC. These results demonstrated the significance of miR-1246 in the regulation of OSCC stemness. Targeting miR-1246-CCNG2 axis may be beneficial to suppress cancer relapse and metastasis in OSCC patients.

MicroRNA-based classifiers for diagnosis of oral cavity squamous cell carcinoma in tissue and plasma

BACKGROUND

MicroRNAs (miRNAs) hold promise as diagnostic cancer biomarkers. Here we aimed to define the miRNome in oral squamous cell carcinoma (OSCC) and normal oral mucosa (NOM), and to identify and validate new diagnostic miRNAs and miRNA combinations in formalin-fixed paraffin-embedded (FFPE) tissue samples and plasma samples.

METHODS

We performed next-generation miRNA sequencing in FFPE tissue samples of OSCC (n = 80) and NOM (n = 8). Our findings were validated by quantitative polymerase chain reaction (qPCR) analysis of OSCC (n = 195) and NOM (n = 103) FFPE tissue samples, and plasma samples from OSCC patients (n = 55) and healthy persons (n = 18).

RESULTS

The OSCC miRNome included 567 miRNAs, 66 of which were differentially expressed between OSCC and NOM. Using qPCR data, we constructed receiver operating curves to classify patients as NOM or OSCC based on miRNA combinations. The area under the curve was of 0.92 from FFPE tissue (miR-204-5p, miR-370, miR-1307, miR-193b-3p, and miR-144-5p), and 1.0 from plasma samples (miR-30a-5p and miR-769-5p). Model calibration and discrimination were evaluated using 10-fold cross-validation.

CONCLUSIONS

Analysis of the miRNome from many OSCC cases improves our knowledge of the importance of individual miRNAs and their predictive potential in OSCC. We successfully identified miRNA classifiers in FFPE OSCC tissue and plasma with a high discriminatory ability between OSCC and NOM. The proposed combination of miR-30a-5p and miR-769-5p in plasma from OSCC patients could serve as a minimal invasive biomarker for diagnosis and control of T-site recurrences.

Let-7c restores radiosensitivity and chemosensitivity and impairs stemness in oral cancer cells through inhibiting interleukin-8

BACKGROUND

The let-7 family of microRNAs has been considered as tumor suppressors in various cancers; however, the role of let-7c in oral squamous cell carcinoma has not been determined yet.

METHODS

In this study, phenotypical behaviors and the radio/chemoresistance were examined subsequent to overexpression of let-7c. In addition, the expression of let-7c in cancer stem cells (CSCs) was evaluated and the effect of let-7c on stemness characteristics was assessed. Also, luciferase activity assays were performed to test whether interleukin (IL)-8 was a putative target of let-7c.

RESULTS

Our results confirmed that the expression of let-7c in CSCs was reduced, while overexpression of let-7c attenuated the oncogenicity. Moreover, ectopic expression of let-7c in CSCs downregulated the stemness hallmarks and the radio/chemoresistance. Expression and secretion of IL-8 in oral CSCs were both reduced following overexpression of let-7c. Besides, the inhibitory effect of let-7c on various stemness phenotypes was reverted by IL-8, indicating that lower expression of let-7c may confer higher cancer stemness through a failure to downregulate IL-8.

CONCLUSION

These findings revealed the significance of let-7c in the contribution of oral cancer stemness and radio/chemoresistance. Targeting let-7c and its downstream IL-8 may be beneficial to prevent cancer recurrence and metastasis of oral squamous cell carcinoma.

Predictive Prognostic Value of Tissue-Based MicroRNA Expression in Oral Squamous Cell Carcinoma: A Systematic Review and Meta-analysis

Oral squamous cell carcinoma (OSCC) is a common type of cancer characterized by a low survival rate, mostly due to local recurrence and metastasis. In view of the importance of predicting tumor behavior in the choice of treatment strategies for OSCC, several studies have attempted to investigate the prognostic value of tissue biomarkers, including microRNA (miRNA). The purpose of this study was to perform a systematic review and meta-analysis to evaluate the relationship between miRNA expression and survival of OSCC patients. Studies were identified by searching on MEDLINE/PubMed, SCOPUS, Web of Science, and Google Scholar. Quality assessment of studies was performed with the Newcastle-Ottawa Scale. Data were collected from cohort studies comparing disease-free survival and overall survival in patients with high miRNA expression compared to those with low expression. A total of 15 studies featuring 1,200 OSCC samples, predominantly from Asia, met the inclusion criteria and were included in the meta-analysis. Poor prognosis correlated with upregulation of 9 miRNAs (miR-21, miR-455-5p, miiR-155-5p, miR-372, miR-373, miR-29b, miR-1246, miR-196a, and miR-181) and downregulation of 7 miRNAs (miR-204, miR-101, miR-32, miR-20a, miR-16, miR-17, and miR-125b). The pooled hazard ratio values (95% confidence interval) related to different miRNA expression for overall survival and disease-free survival were 2.65 (2.07–3.39) and 1.95 (1.28–2.98), respectively. The results of this meta-analysis revealed that the expression levels of specific miRNAs can robustly predict prognosis of OSCC patients.

MiR-204 down-regulation elicited perturbation of a gene target signature common to human cholangiocarcinoma and gastric cancer

Background & Aims

There is high need of novel diagnostic and prognostic tools for tumors of the digestive system, such as gastric cancer and cholangiocarcinoma. We recently found that miR-204 was deeply downregulated in gastric cancer tissues. Here we investigated whether this was common to other tumors of the digestive system and whether this elicited a miR-204-dependent gene target signature, diagnostically and therapeutically relevant. Finally, we assessed the contribution of the identified target genes to the cell cycle progression and clonogenicity of gastric cancer and cholangiocarcinoma cell lines.

Methods

We employed quantitative PCR and Affymetrix profiling for gene expression studies. In silico analysis aided us to identifying a miR-204 target signature in publicly available databases (TGCA). We employed transient transfection experiments, clonogenic assays and cell cycle profiling to evaluate the biological consequences of miR-204 perturbation.

Results

We identified a novel miR-204 gene target signature perturbed in gastric cancer and in cholangiocarcinoma specimens. We validated its prognostic relevance and mechanistically addressed its biological relevance in GC and CC cell lines.

Conclusions

We suggest that restoring the physiological levels of miR-204 in some gastrointestinal cancers might be exploited therapeutically.

MicroRNA meta-signature of oral cancer: evidence from a meta-analysis

AIM

It was the aim of the study to identify commonly deregulated miRNAs in oral cancer patients by performing a meta-analysis of previously published miRNA expression profiles in cancer and matched normal non-cancerous tissue in such patients.

MATERIAL AND METHODS

Meta-analysis included seven independent studies analyzed by a vote-counting method followed by bioinformatic enrichment analysis.

RESULTS

Amongst seven independent studies included in the meta-analysis, 20 miRNAs were found to be deregulated in oral cancer when compared with non-cancerous tissue. Eleven miRNAs were consistently up-regulated in three or more studies (miR-21-5p, miR-31-5p, miR-135b-5p, miR-31-3p, miR-93-5p, miR-34b-5p, miR-424-5p, miR-18a-5p, miR-455-3p, miR-450a-5p, miR-21-3p), and nine were down-regulated (miR-139-5p, miR-30a-3p, miR-376c-3p, miR-885-5p, miR-375, miR-486-5p, miR-411-5p, miR-133a-3p, miR-30a-5p). The meta-signature of identified miRNAs was functionally characterized by KEGG enrichment analysis. Twenty-four KEGG pathways were significantly enriched, and TGF-beta signaling was the most enriched signaling pathway. The highest number of meta-signature miRNAs was involved in the sphingolipid signaling pathway. Natural killer cell-mediated cytotoxicity was the pathway with most genes regulated by identified miRNAs. The rest of the enriched pathways in our miRNA list describe different malignancies and signaling.

CONCLUSIONS

The identified miRNA meta-signature might be considered as a potential battery of biomarkers when distinguishing oral cancer tissue from normal, non-cancerous tissue. Further mechanistic studies are warranted in order to confirm and fully elucidate the role of deregulated miRNAs in oral cancer.

MicroRNA-196a-5p is a potential prognostic marker of delayed lymph node metastasis in early-stage tongue squamous cell carcinoma

MicroRNAs (miRs) are expected to serve as prognostic tools for cancer. However, many miRs have been reported as prognostic markers of recurrence or metastasis in oral squamous cell carcinoma patients. We aimed to determine the prognostic markers in early-stage tongue squamous cell carcinoma (TSCC). Based on previous studies, we hypothesized that miR-10a, 10b, 196a-5p, 196a-3p, and 196b were prognostic markers and we retrospectively performed miR expression analyses using formalin-fixed paraffin-embedded sections of surgical specimens. Total RNA was isolated from cancer tissues and adjacent normal tissue as control, and samples were collected by laser-capture microdissection. After cDNA synthesis, reverse transcription-quantitative polymerase chain reaction was performed. Statistical analyses for patient clinicopathological characteristics, recurrence/metastasis, and survival rates were performed to discern their relationships with miR expression levels, and the 2^−ΔΔCq method was used. miR-196a-5p levels were significantly upregulated in early-stage TSCC, particularly in the lymph node metastasis (LNM) group. The LNM-free survival rate in the low miR-196a-5p ΔΔCq value regulation group was found to be lower than that in the high ΔΔCq value regulation group (P=0.0079). Receiver operating characteristic analysis of ΔΔCq values revealed that miR-196a-5p had a P-value=0.0025, area under the curve=0.740, and a cut-off value=−0.875 for distinguishing LNM. To our knowledge, this is the first study to examine LNM-related miRs in early-stage TSCC as well as miRs and ‘delayed LNM’ in head and neck cancer. miR-196a-5p upregulation may predict delayed LNM. Our data serve as a foundation for future studies to evaluate miR levels and facilitate the prediction of delayed LNM during early-stage TSCC, which prevent metastasis when combined with close follow-up and aggressive adjuvant therapy or elective neck dissection. Moreover, our data will serve as a foundation for future studies to evaluate whether miR-196a-5p can serve as a therapeutic marker for preventing metastasis.

Altered peritumoral microRNA expression predicts head and neck cancer patients with a high risk of recurrence

Head and neck squamous cell carcinoma is typically characterized by a high incidence of local recurrences. It has been extensively shown that mucosa from head and neck squamous cell carcinoma patients carries both genetic and gene expression alterations, which are mostly attributable to major etiologic agents of head and neck squamous cell carcinoma. We previously identified a signature of microRNAs (miRNAs) whose high expression in tumors is predictive of recurrence. Here, we investigated whether the deregulation of miRNA expression in the tumor-surrounding mucosa is correlated to disease recurrence. Specifically, comparing the miRNA expression in matched tumoral, peritumoral, and normal tissues collected from head and neck squamous cell carcinoma patients, we identified 35 miRNAs that are deregulated in both tumoral and peritumoral tissues as compared with normal matched samples. Four of these composed a miRNA signature that predicts head and neck squamous cell carcinoma local recurrence independently from prognostic clinical variables. The predictive power of the miRNA signature increased when using the expression levels derived from both the peritumoral and the tumoral tissues. The expression signal of the miRNAs composing the predictive signature correlated with the transcriptional levels of genes mostly associated with proliferation. Our results show that expression of miRNAs in tumor-surrounding mucosa may strongly contribute to the identification of head and neck squamous cell carcinoma patients at high risk of local recurrence.

Meta-analysis of microRNAs expression in head and neck cancer: uncovering association with outcome and mechanisms

Head and neck squamous cell carcinoma (HNSCC) is often diagnosed at advanced stages, incurring significant high mortality and morbidity. This review explored the risk stratification of miRNAs, and investigated the impact of miRNA networking in HNSCC prognostication. We performed a meta-analysis and a systematic literature search on online databases for papers published prior to December 1, 2016. The list of miRNAs was uploaded to MetacoreTM to construct a protein-protein interaction network, which was used to identify targets of the miRNAs and potential drugs. In addition, a representative network was further validated by immunohistochemistry in a cohort of 100 patients. We found 116 studies that included 8,194 subjects, in which the relationship between miRNA expression and prognosis of HNSCC were analyzed. Significant elevated expressions of 27 miRNAs and decreased expression of 26 miRNAs were associated with poor outcome. After excluding the studies causing heterogeneity, a fixed model was applied, which showed a statistically significant association between increased expression of miR-21 and poor survival (Pooled HR = 1.81,95% CI = 0.66-2.95, P < 0.005). We identified four networks affected by the miRNAs expression and enriched in genes related to metabolic processes and regulation of cell mitogenesis in response to extracellular stimuli. One network point out to 16 miRNAs directly or indirectly involved in the regulation of androgen-receptor (AR). Evaluation of AR protein expression in our cohort revealed that patients with upregulation of AR had poor survival rates (log-rank test, P < 0.005). This study showed that miRNAs have potential prognostic value to serve as screening tool for HNSCC during the follow-up. In addition, the implementation of a network-based analysis may reveal proteins with potential to be used as a biomarker.

Surgical margins in the veterinary cancer patient

In veterinary oncologic specimens, histopathology is the gold standard for determining adequacy of excision. Despite limitations of this technique, the pathologist's interpretation of margin status significantly impacts patient management, including indications for adjuvant therapy. This article aims to summarize peer-reviewed literature as it relates to histologic margin evaluation in veterinary cancer patients. The value of histologic tumour-free margins and technical factors influencing histopathologic margin outcomes are also discussed. We review alternative strategies for determining excisional status, and discuss how an evolving understanding of tumour biology might inform clinical and research perspectives on surgical margins. In doing so, we aim to provide context and a stimulus for future investigations into this important yet incompletely understood topic.

MicroRNA-211 Enhances the Oncogenicity of Carcinogen-Induced Oral Carcinoma by Repressing TCF12 and Increasing Antioxidant Activity

miR-211 expression in human oral squamous cell carcinoma (OSCC) has been implicated in poor patient survival. To investigate the oncogenic roles of miR-211, we generated K14-EGFP-miR-211 transgenic mice tagged with GFP. Induction of oral carcinogenesis in transgenic mice using 4-nitroquinoline 1-oxide (4NQO) resulted in more extensive and severe tongue tumorigenesis compared with control animals. We found that 4NQO and arecoline upregulated miR-211 expression in OSCC cells. In silico and experimental evidence further revealed that miR-211 directly targeted transcription factor 12 (TCF12), which mediated suppressor activities in OSCC cells and was drastically downregulated in tumor tissues. We used GeneChip analysis and bioinformatic algorithms to identify transcriptional targets of TCF12 and confirmed through reporter and ChIP assays that family with sequence similarity 213, member A (FAM213A), a peroxiredoxin-like antioxidative protein, was repressed transcriptionally by TCF12. FAM213A silencing in OSCC cells diminished oncogenic activity, reduced the ALDH1-positive cell population, and increased reactive oxygen species. TCF12 and FAM213A expression was correlated inversely in head and neck carcinoma samples according to The Cancer Genome Atlas. OSCC patients bearing tumors with high FAM213A expression tended to have worse survival. Furthermore, 4NQO treatment downregulated TCF12 and upregulated FAM213A by modulating miR-211 both in vitro and in vivo Overall, our findings develop a mouse model that recapitulates the molecular and histopathologic alterations of human OSCC pathogenesis and highlight a new miRNA-mediated oncogenic mechanism. Cancer Res; 76(16); 4872-86. ©2016 AACR.

MicroRNAs: Non-coding fine tuners of receptor tyrosine kinase signalling in cancer

Emerging evidence point to a crucial role for non-coding RNAs in modulating homeostatic signaling under physiological and pathological conditions. MicroRNAs, the best-characterized non-coding RNAs to date, can exquisitely integrate spatial and temporal signals in complex networks, thereby confer specificity and sensitivity to tissue response to changes in the microenvironment. MicroRNAs appear as preferential partners for Receptor Tyrosine Kinases (RTKs) in mediating signaling under stress conditions. Stress signaling can be especially relevant to disease. Here we focus on the ability of microRNAs to mediate RTK signaling in cancer, by acting as both tumor suppressors and oncogenes. We will provide a few general examples of microRNAs modulating specific tumorigenic functions downstream of RTK signaling and integrate oncogenic signals from multiple RTKs. A special focus will be devoted to epidermal growth factor receptor (EGFR) signaling, a system offering relatively rich information. We will explore the role of selected microRNAs as bidirectional modulators of EGFR functions in cancer cells. In addition, we will present the emerging evidence for microRNAs being specifically modulated by oncogenic EGFR mutants and we will discuss how this impinges on EGFRmut driven chemoresistance, which fits into the tumor heterogeneity-driven cancer progression. Finally, we discuss how other non-coding RNA species are emerging as important modulators of cancer progression and why the scenario depicted herein is destined to become increasingly complex in the future.

Oncogenic MicroRNAs: Key Players in Malignant Transformation

MicroRNAs (miRNAs) represent a class of non-coding RNAs that exert pivotal roles in the regulation of gene expression at the post-transcriptional level. MiRNAs are involved in many biological processes and slight modulations in their expression have been correlated with the occurrence of different diseases. In particular, alterations in the expression of miRNAs with oncogenic or tumor suppressor functions have been associated with carcinogenesis, malignant transformation, metastasis and response to anticancer treatments. This review will mainly focus on oncogenic miRNAs whose aberrant expression leads to malignancy.

MicroRNAs as Important Players and Biomarkers in Oral Carcinogenesis

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