Downregulation of miR-218-5p promotes invasion of oral squamous cell carcinoma cells via activation of CD44-ROCK signaling

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.

MiRNA-related metastasis in oral cancer: moving and shaking

Across the world, oral cancer is a prevalent tumor. Over the years, both its mortality and incidence have grown. Oral cancer metastasis is a complex process involving cell invasion, migration, proliferation, and egress from cancer tissue either by lymphatic vessels or blood vessels. MicroRNAs (miRNAs) are essential short non-coding RNAs, which can act either as tumor suppressors or as oncogenes to control cancer development. Cancer metastasis is a multi-step process, in which miRNAs can inhibit or stimulate metastasis at all stages, including epithelial-mesenchymal transition, migration, invasion, and colonization, by targeting critical genes in these pathways. On the other hand, long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), two different types of non-coding RNAs, can regulate cancer metastasis by affecting gene expression through cross-talk with miRNAs. We reviewed the scientific literature (Google Scholar, Scopus, and PubMed) for the period 2000-2023 to find reports concerning miRNAs and lncRNA/circRNA-miRNA-mRNA networks, which control the spread of oral cancer cells by affecting invasion, migration, and metastasis. According to these reports, miRNAs are involved in the regulation of metastasis pathways either by directly or indirectly targeting genes associated with metastasis. Moreover, circRNAs and lncRNAs can induce or suppress oral cancer metastasis by acting as competing endogenous RNAs to inhibit the effect of miRNA suppression on specific mRNAs. Overall, non-coding RNAs (especially miRNAs) could help to create innovative therapeutic methods for the control of oral cancer metastases.

Stress induced phosphoprotein 1 overexpression controls proliferation, migration and invasion and is associated with poor survival in oral squamous cell carcinoma

Objective

Although there have been remarkable achievements in the molecular landscape of oral squamous cell carcinoma (OSCC) in recent years, bringing advances in the understanding of its pathogenesis, development and progression, little has been applied in the prognosis and choosing the optimal treatment. In this study, we explored the influence of the stress induced phosphoprotein 1 (STIP1), which is frequently reported to be highly expressed in many cancers, in OSCCs.

Methods

STIP1 expression was assessed in the TCGA database and in two independent cohorts by immunohistochemistry. Knockdown strategy was applied in OSCC cell lines to determine the impact of STIP1 on viability, proliferation, migration and invasion. The zebrafish model was applied for studying tumor formation and metastasis in vivo. The association of STIP1 and miR-218-5p was explored by bioinformatics and mimics transfection.

Results

STIP1 was highly expressed in OSCCs and significantly associated with shortened survival and higher risk of recurrence. STIP1 down-regulation decreased proliferation, migration and invasion of tumor cells, and reduced the number of metastases in the Zebrafish model. STIP1 and miR-218-5p were inversely expressed, and the transfection of miR-218-5p mimics into OSCC cells decreased STIP1 levels as well as proliferation, migration and invasion.

Conclusion

Our findings show that STIP1 overexpression, which is inversely associated with miR-218-5p levels, contributes to OSCC aggressiveness by controlling proliferation, migration and invasion and is a determinant of poor prognosis.

circSOX4 Enhances Hepatocellular Carcinoma Progression via miR-218-5p/YY1 Signaling

Liver cancer ranks fifth leading malignancy in incidence and third in mortality worldwide. Recently, its comprehensive treatment has greatly progressed; however, the prognosis is still poor due to difficulties in early diagnosis, high recurrence and metastasis rates, and lack of specific treatment. The search for new molecular biological factors that target the early diagnosis of cancer, predict recurrence, evaluate treatment efficacy, and identify high-risk individuals and specific therapeutic targets during follow-up becomes a great urgent task. circSOX4 is upregulated in lung cancer and plays the role of oncogene. This study attempted to assess circSOX4's role in hepatocellular carcinoma (HCC). HCC tissues and cells were collected to measure circSOX4 level by qRT-PCR, cell behaviors by CCK-8 assay and Transwell assay, and relationship between circSOX4 and downstream targets by dual-luciferase gene assay and RIP. circSOX4 was upregulated in HCC tissue and cell lines, and its level was correlated with reduced patient survival. Interestingly, circSOX4 knockdown reduced HCC behaviors, glucose consumption, and lactate production. Furthermore, circSOX4 knockdown resulted in decreased in vivo tumor growth. circSOX4 was confirmed to target miR-218-5p, and the effect of circSOX4 downregulation on inhibiting tumor growth was diminished after miR-218-5p inhibition or YY1 overexpression in HCC cells. circSOX4 expression is closely associated with HCC through miR-218-5p and YY1-dependent pathways and may be a target and marker for HCC.

LncRNA CCAT1 facilitates the proliferation, invasion and migration of human laryngeal squamous cell carcinoma cells via the miR-218-5p/BMI1

Long non-coding RNAs (LncRNAs) are vital in the treatment of laryngeal squamous cell carcinoma (LSCC). This study estimated the mechanism of lncRNA CCAT1 (CCAT1) in LSCC cells. The expression of CCAT1 in the human laryngeal mucosal epithelial cells (HLCs) and LSCC cells (Hep-2 and TU177) was detected. CCK-8 and Transwell assays were used to evaluate the cell proliferative, migrative, and invasive abilities, respectively. The subcellular localization of CCAT1 was verified by RNA-FISH and cytoplasmic isolation assays. The targeted relationship among CCAT1, miR-218-5p, and BMI1 was verified by dual-luciferase assay. Expressions of miR-218-5p and BMI1 were detected by RT-qPCR. Our results depicted that CCAT1 was highly-expressed in Hep-2 and TU177 cells. Silencing CCAT1 inhibited the proliferation, migration, and invasion of Hep-2 and TU177 cells. Mechanically, CCAT1 regulated the BMI1 expression by competitively binding to miR-218-5p as a competing endogenous RNA (ceRNA), and thus facilitated the growth of Hep-2 and TU177 cells. Downregulation of miR-218-5p or upregulation of BMI1 inhibited the inhibitory effect of silencing CCAT1 on Hep-2 and TU177 cell proliferation, invasion, and migration. In conclusion, our study elicited that lncRNA CCAT1 facilitated the proliferation, migration, and invasion of Hep-2 and TU177 cells by sponging miR-218-5p and regulating the downstream BMI1.

Construction of miRNA-mRNA regulatory network and analysis of hub genes in oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) severely affects the quality of life and the 5-year survival rate is low. Exploring the potential miRNA-mRNA regulatory network and analyzing hub genes and clinical data can provide a theoretical basis for further elucidating the pathogenesis of OSCC.

METHODS

The miRNA expression datasets of GSE113956 and GSE124566 and mRNA expression datasets of GSE31056, GSE37991 and GSE13601 were obtained from the Gene Expression Omnibus databases. The differentially expressed miRNAs (DEMs) and mRNAs (DEGs) were screened using GEO2R. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed by DAVID database. The PPI network was established through STRING database and the hub genes were preliminarily screened out by Cytoscape software. After identifying the hub genes in the TCGA database, we predicted the potential DEM transcription factors, constructed a miRNA-mRNA regulatory network, and analyzed the relationship between the hub genes and clinical data.

RESULTS

A total of 28 DEMs and 764 DEGs were screened out, which were composed of 285 up-regulated genes and 479 down-regulated genes. Enrichment analysis showed that up-regulation of DEGs were mainly enriched in extracellular matrix organization and cancer-related pathway, while down-regulation of DEGs were mainly enriched in muscular system process and adrenaline signal transduction. After preliminary screening by PPI network and identification in TCGA, the up-regulated FN1, COL1A1, COL1A2, AURKA, CCNB1, CCNA2, SPP1, CDC6, and down-regulated ACTN2, TTN, IGF1, CAV3, MYL2, DMD, LDB3, CSRP3, ACTA1, PPARG were identified as hub genes. The miRNA-mRNA regulation network showed that hsa-miR-513b was the DEM with the most regulation, and COL1A1 was the DEG with the most regulation. In addition, CDC6, AURKA, CCNB1 and CCNA2 were related to overall survival and tumor differentiation.

CONCLUSIONS

The regulatory relationship of hsa-miR-513b/ CDC6, CCNB1, CCNA2 and the regulatory relationship of hsa-miR-342-5p /AURKA were not only verified in the miRNA-mRNA regulatory network but also related to overall survival and tumor differentiation. These results indicated that they participated in the cellular regulatory process, and provided a molecular mechanism model for the study of pathogenesis.

hsa_circ_0023305 Enhances Laryngeal Squamous Cell Carcinoma Progression and Modulates TRPM7 via miR-218-5p Sponging

Recently, circular RNAs have been shown to function as critical regulators of many human cancers. However, the circRNA mechanism in laryngeal squamous cell carcinoma (LSCC) remains elusive. Recent investigations using bioinformatics analysis revealed high expression of hsa_circ_0023305 in LSCC tissues compared to normal tissues. Furthermore, we discovered that hsa_circ_0023305 expression level was positively correlated to tumor/node/metastasis (TNM) stage as well as lymph node metastasis in LSCC. Moreover, higher hsa_circ_0023305 levels were correlated to poorer LSCC patient outcomes. Knockdown of hsa_circ_0023305 significantly inhibited LSCC cell proliferation, invasion, and migration abilities. Our team validated that hsa_circ_0023305 functioned as a miR-218-5p sponge from a mechanistic perspective, targeting the melastatin-related transient receptor potential 7 (TRPM7) in LSCC cells. TRPM7 regulates a nonselective cation channel and promotes cancer proliferation and metastasis. Our data demonstrated that miR-218-5p was downregulated in LSCC and that miR-218-5p upregulation repressed LSCC proliferation and invasion both in vivo and in vitro. Additionally, we found that hsa_circ_0023305-mediated upregulation of TRPM7 inhibited miR-218-5p and contributed to LSCC migration, proliferation, and invasion. In summary, these data propose a new mechanism by which the hsa_circ_0023305/miR-218-5p/TRPM7 network enhances LSCC progression.

Identification of miR-199-5p and miR-199-3p Target Genes: Paxillin Facilities Cancer Cell Aggressiveness in Head and Neck Squamous Cell Carcinoma

Our previous study revealed that the miR-199 family (miR-199a-5p/-3p and miR-199b-5p/-3p) acts as tumor-suppressive miRNAs in head and neck squamous cell carcinoma (HNSCC). Furthermore, recent studies have indicated that the passenger strands of miRNAs are involved in cancer pathogenesis. The aim of this study was to identify cancer-promoting genes commonly regulated by miR-199-5p and miR-199-3p in HNSCC cells. Our in silico analysis and luciferase reporter assay identified paxillin (PXN) as a direct target of both miR-199-5p and miR-199-3p in HNSCC cells. Analysis of the cancer genome atlas (TCGA) database showed that expression of PXN significantly predicted a worse prognosis (5-year overall survival rate; p = 0.0283). PXN expression was identified as an independent factor predicting patient survival according to multivariate Cox regression analyses (p = 0.0452). Overexpression of PXN was detected in HNSCC clinical specimens by immunostaining. Functional assays in HNSCC cells showed that knockdown of PXN expression attenuated cancer cell migration and invasion, suggesting that aberrant expression of PXN contributed to HNSCC cell aggressiveness. Our miRNA-based approach will provide new insights into the molecular pathogenesis of HNSCC.

Perspectives on miRNAs Targeting DKK1 for Developing Hair Regeneration Therapy

Androgenetic alopecia (AGA) remains an unsolved problem for the well-being of humankind, although multiple important involvements in hair growth have been discovered. Up until now, there is no ideal therapy in clinical practice in terms of efficacy and safety. Ultimately, there is a strong need for developing a feasible remedy for preventing and treating AGA. The Wnt/β-catenin signaling pathway is critical in hair restoration. Thus, AGA treatment via modulating this pathway is rational, although challenging. Dickkopf-related protein 1 (DKK1) is distinctly identified as an inhibitor of canonical Wnt/β-catenin signaling. Thus, in order to stimulate the Wnt/β-catenin signaling pathway, inhibition of DKK1 is greatly demanding. Studying DKK1-targeting microRNAs (miRNAs) involved in the Wnt/β-catenin signaling pathway may lay the groundwork for the promotion of hair growth. Bearing in mind that DKK1 inhibition in the balding scalp of AGA certainly makes sense, this review sheds light on the perspectives of miRNA-mediated hair growth for treating AGA via regulating DKK1 and, eventually, modulating Wnt/β-catenin signaling. Consequently, certain miRNAs regulating the Wnt/β-catenin signaling pathway via DKK1 inhibition might represent attractive candidates for further studies focusing on promoting hair growth and AGA therapy.

Long non-coding RNA HOXA-AS3 promotes cell proliferation of oral squamous cell carcinoma through sponging microRNA miR-218-5p

Increasing evidence demonstrated long non-coding RNAs (lncRNAs) play important roles in the occurrence and development of oral squamous cell carcinoma (OSCC). This study aimed to explore the role and molecular mechanism of lncRNA HOXA-AS3 in the progression of OSCC. Here, we found that the expression of lncRNA HOXA-AS3 was upregulated in OSCC tissues and cell lines compared with the para-cancerous tissues and normal human oral keratinocyte (NHOK), respectively. Inhibition of HOXA-AS3 significantly inhibited the proliferation and colony formation of OSCC cells. Further, the luciferase reporter assay showed that HOXA-AS3 was directly bound to miR-218-5p. Moreover, the expression of miR-218-5p was negatively regulated by HOXA-AS3, and miR-218-5p could inhibit the expression of collagen type I alpha1 (COL1A1) and lysophosphatidylcholine acyltransferase 1 (LPCAT1). In addition, silencing miR-218-5p reversed the inhibitory effect of HOXA-AS3 knockdown on the proliferative potential of OSCC cells. In summary, our study illustrated that HOXA-AS3 promoted cancer cell proliferation in OSCC, possibly by sponging miR-218-5p for the first time, which provides a new target or a potential diagnostic biomarker for OSCC.

ZIKV Infection and miRNA Network in Pathogenesis and Immune Response

Over the years, viral infections have caused severe illness in humans. Zika Virus (ZIKV) is a flavivirus transmitted by mosquito vectors that leads to notable neurological impairment, whose most dramatic impact is the Congenital ZIKV Syndrome (CZS). ZIKV targets neuronal precursor cells leading to apoptosis and further impairment of neuronal development, causing microcephaly, lissencephaly, ventriculomegaly, and calcifications. Several regulators of biological processes are involved in CZS development, and in this context, microRNAs (miRNAs) seem to have a fundamental role. miRNAs are important regulators of protein translation, as they form the RISC silencing complex and interact with complementary mRNA target sequences to further post-transcriptional repression. In this context, little is known about their participation in the pathogenesis of viral infections. In this review, we discuss how miRNAs could relate to ZIKV and other flavivirus infections.

Changes in cytoarchitecture and mobility in B16F1 melanoma cells induced by 5-Br-2'-dU coincide with Rock2, miRNAs 138-5p and 455-3p reciprocal expressions

ROCK2 is a protein involved in the restructuring of the cytoskeleton in cell adhesion and contractibility processes. miR-138-5p and miR-455-3p regulate Rock2 expression, cell proliferation, migration, and invasion in different experimental cell models. However, their participation in the cytoarchitecture and mobility of B16F1 melanoma cells exposed to 5-Br-2'-dU is partially known. This work aimed to analyze ROCK2 and miRs 138-5p and 455-3p expression associated with morphological and mobility changes of B16F1 mouse melanoma cells exposed to the thymidine analog 5-Bromo-2'-deoxyuridine (5-Br-2'-dU). We observed an increase (2.2X n = 3, p < 0.05) in the cell area, coinciding with an increase in cell diameter (1.27X n = 3, p < 0.05), as well as greater cell granularity, capacity for circularization, adhesion, which was associated with more significant polymerization of F-actin, collapsed in the intermediate filaments of vimentin (VIM), and coinciding with a decrease in migration (87%). Changes coincided with a decrease in Rock2 mRNA expression (2.88X n = 3, p < 0.05), increased vimentin and a reciprocal decrease in miR-138-5p (1.8X), and an increase in miR-455-3p (2.39X). The Rock2 kinase inhibitor Y27632 partially rescued these changes. These results suggest ROCK2 and VIM regulate the morphological and mobility changes of B16 melanoma cells after exposure to 5-Br-2'-dU, and its expression may be reciprocally regulated, at least in part, by miR-138-5p and miR-455-3p.

LncRNA SNHG12 regulates ox-LDL-induced endothelial cell injury by the miR-218-5p/IGF2 axis in atherosclerosis

Atherosclerosis (AS) is a cardiovascular disorder accompanied by endothelial dysfunction. Extensive evidence demonstrates the regulatory functions of long noncoding RNAs (lncRNAs) in cardiovascular disease, including AS. Here, the function of lncRNA small nucleolar RNA host gene 12 (SNHG12) in AS progression was investigated. A cell model of AS was established in human umbilical endothelial cells (HUVECs) using oxidative low-density lipoprotein (ox-LDL). CCK-8, flow cytometry, TUNEL, ELISA, and western blotting analyses were performed. Apolipoprotein E-deficient (apoE-/-) mice fed a Western diet were used as in vivo models of AS. RT-qPCR determined the levels of SNHG12, microRNA-218-5p (miR-218-5p) and insulin-like growth factor-II (IGF2). The molecular mechanisms were investigated using luciferase reporter and RNA pull-down assays. We found that SNHG12 and IGF2 expression levels were high and miR-218-5p expression levels were low in AS patients and ox-LDL-treated HUVECs. SNHG12 depletion attenuated ox-LDL-induced injury in HUVECs, whereas miR-218-5p suppression partially abated this effect. Moreover, IGF2 overexpression prevented the alleviative role of miR-218-5p in ox-LDL-treated HUVECs. SNHG12 upregulated IGF2 expression by sponging miR-218-5p. More importantly, SNHG12 increased proinflammatory cytokine production and augmented atherosclerotic lesions in vivo. Overall, SNHG12 promotes the development of AS by the miR-218-5p/IGF2 axis.

Effects of miR-224-5p-enhanced downregulation of pannexin-1 on docetaxel-induced apoptosis in amoeboid-like CD44high oral cancer cells

We previously found that microRNAs play major roles in the maintenance of amoeboid-like oral squamous cell carcinoma (OSCC) cells with high expression of CD44 (CD44^high ). However, the roles of microRNAs in chemotherapeutic resistance exhibited by CD44^high amoeboid-like OSCC cells are unclear. Here, docetaxel-induced apoptosis was examined in CD44^high OSCC cells (CD44^high OM-1 cells) cultured on laminin-coated silicone gel. Amoeboid-like CD44^high OSCC cells exhibited robust resistance to docetaxel-induced apoptosis and significant upregulation of miR-224-5p expression compared with epithelial-like CD44^high OSCC cells and mesenchymal-like CD44^high OSCC cells. The expression of pannexin-1 (PANX1), a channel-forming protein that regulates the release of ATP, was significantly upregulated following transfection of amoeboid-like CD44^high OSCC cells with an miR-224-5p inhibitor. These results suggest that miR-224-5p inhibits PANX1 expression. Furthermore, miR-224-5p inhibitor-transfected amoeboid-like CD44^high OSCC cells exhibited significant enhancement of the proportion of apoptotic cells; however, this effect was significantly inhibited by knockdown of PANX1 with PANX1 small interfering RNA. Additionally, the miR-224-5p inhibitor-enhanced extracellular ATP levels were significantly reduced by PANX1 knockdown. These findings imply that miR-224-5p plays a vital role in the resistance to docetaxel-induced apoptosis by attenuating PANX1-induced ATP discharge. Moreover, amoeboid-like CD44^high OSCC cells may be involved in chemotherapeutic resistance of OSCC.

miR-218-5p inhibits the malignant progression of glioma via targeting TCF12

Several studies have shown the ability of transcription factor 12 (TCF12) to promote tumor malignant progression, but its function in glioma cells has not been fully elucidated. In this study, we analyzed the data from TCGA by bioinformatics and found that in glioma tissue, TCF12 was conspicuously highly expressed while miR-218-5p was significantly low-expressed. The downregulation of miR-218-5p was correlated with adverse prognosis in patients with glioma. miR-218-5p was found to be negatively associated with TCF12 by Pearson correlation analysis, and dual luciferase assay was employed to verify that miR-218-5p and TCF12 had a targeting relationship. qRT-PCR and Western blot assays were used to verify that the expression of TCF12 was regulated by its upstream regulator miR-218-5p. Moreover, cell experiments validated that overexpressed TCF12 could promote the proliferation, migration, and invasion of glioma cells and inhibit their apoptosis, whereas overexpressing miR-218-5p at the same time could reverse this phenomenon. Our study demonstrates the regulatory mechanism of the miR-218-5p/TCF12 axis in gliomas, which lays a foundation for searching for new therapeutic approaches for glioma.

CD44 polymorphisms and its variants, as an inconsistent marker in cancer investigations

Among cell surface markers, CD44 is considered the main marker for identifying and isolating the cancer stem cells (CSCs) among other cells and has attracted significant attention in a variety of research areas. Many studies have shown the essential roles of CD44 in initiation, metastasis, and tumorigenesis in different types of cancer; however, the validity of CD44 as a therapeutic or diagnostic target has not been fully confirmed in some other studies. Whereas the association of specific single nucleotide polymorphisms (SNPs) in the CD44 gene and related variants with cancer risk have been observed in clinical investigations, the significance of these findings remains controversial. Here, we aimed to provide an up-to-date overview of recent studies on the association of CD44 polymorphisms and its variants with different kinds of cancer to determine whether or not it can be used as an appropriate candidate for cancer tracking.

LncRNA MIR155HG contributes to smoke-related chronic obstructive pulmonary disease by targeting miR-128-5p/BRD4 axis

Chronic obstructive pulmonary disease (COPD) is a common airway disease characterized by an exaggerated pulmonary inflammatory response. Long noncoding MIR155 host gene (lncRNA MIR155HG) has been identified to be related to the macrophage polarization in COPD. However, the detailed function of MIR155HG in cigarette smoke (CS)-mediated COPD remains largely unknown. The expression level of MIR155HG was elevated while miR-218-5p was decreased in lung tissues of smokers without or with COPD, especially in smokers with COPD, and cigarette smoke extract (CSE)-treated human pulmonary microvascular endothelial cell (HPMECs) in a dose- and time-dependent manner. Then, functional experiments showed that MIR155HG deletion could reverse CSE exposure-induced apoptosis and inflammation in HPMECs. MiR-218-5p was confirmed to be a target of MIR155HG and rescue assay showed miR-218-5p inhibitor attenuated the inhibitory action of MIR155HG knockdown on CSE-induced HPMECs. Subsequently, miR-218-5p was found to target bromodomain containing 4 (BRD4) directly, and miR-218-5p overexpression overturned CSE-induced injury of HPMECs via regulating BRD4. Additionally, co-expression analysis indicated MIR155HG indirectly regulated BRD4 expression in HPMECs via miR-218-5p. Thus, we concluded that MIR155HG contributed to the apoptosis and inflammation of HPMECs in smoke-related COPD by regulating miR-128-5p/BRD4 axis, providing a novel insight on the pathogenesis of COPD and a therapeutic strategy on COPD treatments.

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.

MiR-524 suppressed the progression of oral squamous cell carcinoma by suppressing Metadherin and NF-κB signaling pathway in OSCC cell lines

OBJECTIVES

The aim of the present study was to explore the functional role of miR-524 in oral squamous cell carcinoma (OSCC) and determine its underlying mechanism.

MATERIALS AND METHODS

Tumor tissues and adjacent tissues were obtained from 55 patients with OSCC (20 females and 35 males) with a mean age of 54 years (range from 24 to 72 years). Additionally, OSCC cell lines culture was used and Reverse transcription‑quantitative PCR (RT-qPCR) was applied to measure the expression of miR-524 in OSCC tissues and cells. The protein density of Metadherin (MTDH) in OSCC tissues was detected by Immunohistochemistry (IHC) assay. MiR-524 mimic was employed to investigate the impact of miR-524 on proliferation, migration, and invasion using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and transwell assays. The dual luciferase reporter assay was utilized to investigate the interaction between MTDH and miR-524 expression. Cells transfected with miR-524 mimic and pcDNA-MTDH were subjected to western blot to investigate the role of NF-κB signaling in miR-524/MTDH axis mediated cell proliferation, migration, and invasion.

RESULTS

MiR-524 expression was decreased significantly in OSCC tissues compared to adjacent tissues, and closely related to clinical stage, tumor size, and lymph node metastasis. Over-expression of miR-524 suppressed the proliferation, migration, and invasion of OSCC cells. Luciferase reporter assay results demonstrated that MTDH was the target gene of miR-524. Over-expression of miR-524 reduced MTDH expression and inhibited NF-κB signaling pathway. Rescue experiments revealed that over-expression of MTDH partially reversed the efficacy of miR-524 mimic on OSCC cells.

CONCLUSIONS

These results indicated that miR-524 inhibits the activation of NF-κB signaling pathway via inhibiting MTDH, resulting in the suppression of cell proliferation, migration, and invasion.

Plasma miR-218a-5p as a biomarker for acute cholestatic liver injury in rats and investigation of its pathophysiological roles

MicroRNAs (miRNA) have received considerable attention as potential biomarkers for drug-induced liver injury. We recently reported that the plasma levels of miR-143-3p and miR-218a-5p increased in severe cholestasis in rats. This study aimed to investigate whether these miRNAs increase in a severity-dependent manner and to elucidate their pathophysiological roles in cholestasis. Male Sprague-Dawley rats were orally administered different doses of α-naphthylisothiocyanate or 4,4-methylenedianiline to induce acute cholestasis. They were also orally administered acetaminophen or thioacetamide to induce hepatocellular injury. We found that plasma miR-143-3p and miR-218a-5p levels increased in a dose-dependent manner in cholestatic rats but not in hepatocellular injury. Bioinformatic analysis provided putative target genes of hsa-miR-218-5p, rno-miR-218a-5p, and mmu-miR-218-5p, among which GNAI2, PPP1CB, and PPP2R5A were experimentally validated as their direct target genes in human cholangiocyte line MMNK-1. Proliferation of MMNK-1 cells was significantly suppressed after overexpression of miR-218-5p and transduction of siRNAs for GNAI2, PPP1CB, and PPP2R5A. In the cholestatic livers of rats, Ppp1cb and Ppp2r5a expression levels decreased, whereas Gnai2 expression levels increased compared with those in vehicle-treated rats, suggesting that Ppp1cb and Ppp2r5a may be under the control of miR-218a-5p in vivo. In conclusion, our data suggest that miR-218(a)-5p is involved in the suppression of cholangiocyte proliferation by inhibiting the expression of PPP1CB and PPP2R5A, thereby contributing to the pathogenesis of cholestasis; and miR-218a-5p leaks into the plasma probably from damaged cholangiocytes in a severity-dependent manner in rats. Therefore, miR-218a-5p overexpression could be one of the underlying mechanisms of acute cholestatic liver injury in rats.

The effect of LncRNA SNHG16 on vascular smooth muscle cells in CHD by targeting miRNA-218-5p

PURPOSE

To explore the role of SNHG16 in coronary heart disease (CHD) and its effect on vascular smooth muscle cells via miR-218-5p.

METHODS

A quantitative real time polymerase chain reaction (qRT-PCR) assay was carried out to determine the expression of serum SNHG16 and miR-218-5p in the observation group before and after treatment and in the control group. Then, receiver operating characteristic (ROC) curves were drawn to analyze the value of SNHG16 and miR-218-5p in the diagnosis and prognosis prediction of CHD. Furthermore, purchased coronary artery smooth muscle cells (HCASMC) were transfected with SNHG16 mimics, SNHG16 inhibitor, miR-218-5p mimics, miR-218-5p inhibitor, or negative control, and then the cell proliferation, migration, apoptosis, and apoptosis-related proteins (Bax, Bcl-2, and Caspase-3) and Wnt/β-catenin signaling pathway-related proteins (c-myc and β-catenin) in the cells were detected.

RESULTS

Both SNHG16 and miR-218-5 had good predictive value for the development and recurrence of CHD (P < 0.001). In addition, cell experiments showed that inhibition of SNHG16 weakened the proliferation and migration of HCASMC cells and intensified their apoptosis, SNHG16 and miR-218-5p had the same binding sites, and the dual luciferase reporter assay revealed that the fluorescence activity of HG16-WT was inhibited by transfected miR-mimics, but enhanced by transfected miR-inhibitor (both P < 0.050). Furthermore, the rescue experiment revealed that the effect of inhibiting SNHG16 on HCASMC cells was completely reversed by miR-218-5p (P > 0.050).

CONCLUSIONS

Highly expressed SNHG16 targetedly regulates miR-218-5p and promotes the proliferation and migration of HCASMC via the Wnt/β-catenin signaling pathway, giving rise to CHD.

MicroRNA profile in the squamous cell carcinoma: prognostic and diagnostic roles

Head and neck squamous cell carcinomas (HNSCCs) are human malignancies associated with both genetic and environmental factors. MicroRNAs (miRNAs) as a group of small non-coding RNAs have prominent roles in the development of this kind of cancer. Expressions of several miRNAs have been demonstrated to be increased in HNSCC samples vs. non-malignant tissues. In silico prediction tools and functional analyses have confirmed the function of some miRNAs in the modulation of cancer-associated targets, thus indicating these miRNAs as onco-miRs. Moreover, numerous miRNAs have been down-regulated in HNSCC samples. Their targets mostly enhance cell proliferation or inhibit apoptosis. miRNAs signature has practical implications in the diagnosis, staging, and management of HNSC. Most notably, numerous miRNAs have been shown to alter response of tumor cells to anti-cancer drugs such as cisplatin and doxorubicin. Circulating levels of these small transcripts have been suggested as promising biomarkers for diagnosis of HNSCC. In the present manuscript, we sum up the available literature regarding the miRNAs signature in HNSCC and their role as diagnostic/prognostic biomarkers.

ARPP-19 Mediates Herceptin Resistance via Regulation of CD44 in Gastric Cancer

Purpose

As the first-line drug for treatment of HER2-positive metastatic gastric cancer (GC), Herceptin exhibits significant therapeutic efficacy. However, acquired resistance of Herceptin limits the therapeutic benefit of gastric cancer patients, in which the molecular mechanisms remain to be further determined.

Methods

Quantitative real-time polymerase chain reaction was performed to detect the mRNA levels of ARPP-19 and CD44 in GC cells. Protein levels were determined using Western blot and IHC staining. MTT and soft agar colony formation assays were used to measure cell proliferation. Xenograft model was established to verify the functional role of ARPP-19 in Herceptin resistance in vivo. Sphere formation assay was conducted to determine cell stemness.

Results

We observed ARPP-19 was up-regulated in Herceptin resistance gastric cancer cells NCI-N87-HR and MKN45-HR. The forced expression of ARPP-19 promoted, whereas the silencing of ARPP-19 impaired Herceptin resistance of HER2-positive gastric cancer cells both in vitro and in vivo. Moreover, ARPP-19 significantly enhanced the sphere formation capacity and CD44 expression, CD44 was also a positive factor of Herceptin resistance in HER2-positive gastric cancer cells. In addition, high level of ARPP-19 was positively associated with Herceptin resistance and poor survival rate of gastric cancer patients.

Conclusion

We have demonstrated that ARPP-19 promoted Herceptin resistance of gastric cancer via up-regulation of CD44, our study suggested that ARPP-19 could be a potential diagnostic and therapeutic candidate for HER2-positive gastric cancer.

Long non‑coding RNA NR2F1‑AS1 facilitates the osteosarcoma cell malignant phenotype via the miR‑485‑5p/miR‑218‑5p/BIRC5 axis

Long non-coding RNA (lncRNA) NR2F1 antisense RNA 1 (NR2F1-AS1) has been reported to be an oncogene in several cancer types, including osteosarcoma (OS). However, the underlying fundamental molecular mechanism of NR2F1-AS1 in OS remains largely unknown, which the present study aimed to elucidate. The present study demonstrated that NR2F1-AS1 expression is markedly increased in OS, and NR2F1-AS1 was shown to exert oncogenic functions in OS. Further molecular mechanistic studies revealed that microRNA (miR)-485-5p and miR-218-5p were direct targets of NR2F1-AS1. More importantly, miR-485-5p and miR-218-5p exhibited low expression levels and were negatively correlated with NR2F1-AS1 expression in OS tissues. It was then identified that baculoviral inhibitor of apoptosis repeat-containing 5 (BIRC5) was a direct target of miR-485-5p and miR-218-5p in OS cells. Furthermore, a series of experiments suggested that NR2F1-AS1 affects the proliferation, migration, invasion and apoptosis of OS cells by regulating BIRC5. Finally, it was revealed that silencing of NR2F1-AS1 repressed the OS cell malignant phenotype by binding with miR-485-5p and miR-218-5p, and then downregulating BIRC5 expression, which suggests that the NR2F1-AS1/miR-485-5p/miR-218-5p/BIRC5 axis could be a potential target for treating OS.

MicroRNA-299-3p/FOXP4 Axis Regulates the Proliferation and Migration of Oral Squamous Cell Carcinoma

MicroRNAs are noncoding RNAs of 21 to 23 nucleotides in length that play important roles in almost all biological pathways. The roles of microRNA-299-3p in the development and progression of oral squamous cell carcinoma remain unclear. Expression level of microRNA-299-3p in oral squamous cell carcinoma cell lines was analyzed. Then, the effects of microRNA-299-3p on oral squamous cell carcinoma cell proliferation and migration were investigated. Moreover, bioinformation algorithm and Western blot were conducted to explore whether forkhead box P4 was a direct target of miR-299-3p. We showed that microRNA-299-3p expression was significantly reduced in oral squamous cell carcinoma cell lines. Next, overexpression of microRNA-299-3p was found to inhibit oral squamous cell carcinoma cell proliferation and migration but promote apoptosis. In addition, forkhead box P4 was identified as a functional target of microRNA-299-3p. Our results provide a new perspective for the mechanisms underlying the progression of oral squamous cell carcinoma and a novel target for the treatment of oral squamous cell carcinoma.

MicroRNA-29b-3p suppresses oral squamous cell carcinoma cell migration and invasion via IL32/AKT signalling pathway

Oral squamous cell carcinoma (OSCC) is aggressive accompanied with poor prognosis. We previously isolated the most invasive cells resembling the invasive tumour front by microfluidic technology and explored their differentially expressed microRNAs (miRNAs) in our previous work. Here, we verified the miR‐29b‐3p as a guarder that suppressed migration and invasion of OSCC cells and was down‐regulated in the most invasive cells. Besides that, the invasion suppression role of miR‐29b‐3p was achieved through the IL32/AKT pathway. Thus, miR‐29b‐3p and IL32 might serve as therapeutic targets for blocking the progression and improving the outcome of OSCC.

The role of the miR1976/CD105/integrin αvβ6 axis in vaginitis induced by Escherichia coli infection in mice

Vaginitis is very common among women, especially women of childbearing age, and is associated with significantly increased risk of preterm birth and pelvic inflammatory diseases. An imbalance in the vaginal flora, the primary cause of vaginitis, promotes the initiation and progression of vaginal infections. However, the responsible mechanisms are still poorly understood. Using a murine vaginitis model of Escherichia coli infection, we demonstrated that decreased expression of microRNA1976 and increased expression of CD105 and integrin αvβ6 were closely associated with the progression of vaginal infection. Importantly, we demonstrated for the first time that the microRNA1976/CD105/integrin αvβ6 axis regulates E. coli-mediated vaginal infection in mice, as evidenced by the finding that E. coli-induced vaginal infection was reversed by microRNA1976 overexpression and exacerbated by CD105 overexpression. The regulation of CD105 and integrin αvβ6 by microRNA1976 was further confirmed in a murine model of vaginitis with adenoviral vector treatment. Taken together, our data suggested that microRNA1976 negatively regulates E. coli-induced vaginal infection in mice at least in part by suppressing CD105 and integrin αvβ6 expression. These findings may provide new insight into the mechanisms of E. coli-induced vaginitis, identify a novel diagnostic biomarker and a potential therapeutic target for flora imbalance-associated vaginitis.

Downregulation of miR-218 by nicotine promotes cell proliferation through targeting CDK6 in non-small cell lung cancer

BACKGROUND

Nicotine, an important component of tobacco, is a major risk factor of lung cancer, but the mechanism through which nicotine promotes lung cancer development remains unclear.

METHODS

Eighty patients with lung cancer were enrolled in this study, 34 of whom did not smoke and the others did. The expression of miR-218 and CDK6 messenger RNA (mRNA) was measured using quantitative reverse transcription polymerase chain reaction (qRT-PCR). A luciferase reporter system was used to identify the direct target of miR-218. The protein expression of CDK6 was analyzed by using Western blotting. Cell proliferation was analyzed using an approach of calculation of cell number under a microscope.

RESULTS

Nicotine decreased miR-218 expression in non-small cell lung cancer (NSCLC) cells and promoted proliferation of NSCLC cells. Smoking patients with NSCLC had lower expression of miR-218 in tumor compared with NSCLC patients who did not smoke. We found that miR-218 directly targeted the CDK6 mRNA 3'untranslated region and inhibited its expression in NSCLC cells and also observed a negative correlation between the expression of miR-218 and CDK6 mRNA in lung cancer tissues. Furthermore, miR-218- or nicotine-induced proliferative effects of NSCLC cells were rescued by the recovery of the expression level of CDK6.

CONCLUSION

Nicotine promotes proliferation of NSCLC cells through regulating the miR-218/CDK6 axis, which may be a potential therapeutic target for lung cancer.

Prospective applications of microRNAs in oral cancer

MicroRNAs (miRNAs) are non-coding RNA molecules that are generally encoded by endogenous genes and exert suppressive effects on post-transcriptional regulation of their target genes by translation repression or degradation of mRNA. This subsequently mediates activation or blocking of downstream signaling pathways associated with oral malignancies. Aberrant levels of certain miRNAs have been identified in cell experiments, clinical carcinomatous specimens, saliva, serum or plasma samples of patients with oral malignancies. miRNAs are associated with multiple aspects of oral cancer, including tumor growth, cellular proliferation, apoptosis, migration, invasion, metastasis, glycometabolism, radiosensitivity and chemosensitivity. miRNAs have the potential to be used in clinical applications as minimally invasive or non-invasive tools for early diagnosis and prognosis by the detection of serum, plasma and saliva levels, and may provide a new ancillary or additional reference index of traditional pathological grading and clinical staging. Furthermore, miRNAs may be used as prognostic biomarkers or targets for novel therapies for oral cancer.

Role of miRNA-Regulated Cancer Stem Cells in the Pathogenesis of Human Malignancies

Recent biomedical discoveries have revolutionized the concept and understanding of carcinogenesis, a complex and multistep phenomenon which involves accretion of genetic, epigenetic, biochemical, and histological changes, with special reference to MicroRNAs (miRNAs) and cancer stem cells (CSCs). miRNAs are small noncoding molecules known to regulate expression of more than 60% of the human genes, and their aberrant expression has been associated with the pathogenesis of human cancers and the regulation of stemness features of CSCs. CSCs are the small population of cells present in human malignancies well-known for cancer resistance, relapse, tumorigenesis, and poor clinical outcome which compels the development of novel and effective therapeutic protocols for better clinical outcome. Interestingly, the role of miRNAs in maintaining and regulating the functioning of CSCs through targeting various oncogenic signaling pathways, such as Notch, wingless (WNT)/β-Catenin, janus kinases/ signal transducer and activator of transcription (JAK/STAT), phosphatidylinositol 3-kinase/ protein kinase B (PI3/AKT), and nuclear factor kappa-light-chain-enhancer of activated B (NF-kB), is critical and poses a huge challenge to cancer treatment. Based on recent findings, here, we have documented the regulatory action or the underlying mechanisms of how miRNAs affect the signaling pathways attributed to stemness features of CSCs, such as self-renewal, differentiation, epithelial to mesenchymal transition (EMT), metastasis, resistance and recurrence etc., associated with the pathogenesis of various types of human malignancies including colorectal cancer, lung cancer, breast cancer, head and neck cancer, prostate cancer, liver cancer, etc. We also shed light on the fact that the targeted attenuation of deregulated functioning of miRNA related to stemness in human carcinogenesis could be a viable approach for cancer treatment.

The effects of miR-429 on cell migration and invasion by targeting Slug in esophageal squamous cell carcinoma

Increasing evidence indicates that microRNAs may play important roles in tumor development and may take part in different processes in different cancers. miR-429 is known as a cancer suppressor or oncogene that is dysregulated in different malignancies, including esophageal squamous cell carcinoma (ESCC). However, the effect of miR-429 in ESCC has not been fully explored. The purpose of this study was to investigate the functions of miR-429 in ESCC. qRT-PCR assays were performed to detect miR-429 expression in ESCC tissues and cell lines. To assess the effects of miR-429 on ESCC cells, wound healing and transwell assays were used. Luciferase reporter and western blot assays were employed to determine whether Slug is a major target of miR-429.Our results showed that the expression levels of miR-429 in ESCC tissues and cells were lower than in normal esophageal epithelial tissues and cells. Furthermore, overexpression of endogenous miR-429 inhibited the migration and invasion of ESCC cell lines. In addition, Luciferase reporter and western blot assays provided evidence that miR-429 can bind to the 3' untranslated regions of Slug to regulate its expression and that of downstream epithelial-to-mesenchymal transition (EMT) markers. We found that Slug serves as a major target of miR-429. miR-429 plays a vital role in ESCC progression and represents a new therapeutic target for ESCC.

Exosomes, metastases, and the miracle of cancer stem cell markers

Cancer-initiating cells (CIC) are the driving force in tumor progression. There is strong evidence that CIC fulfill this task via exosomes (TEX), which modulate and reprogram stroma, nontransformed cells, and non-CIC. Characterization of CIC, besides others, builds on expression of CIC markers, many of which are known as metastasis-associated molecules. We here discuss that the linkage between CIC/CIC-TEX and metastasis-associated molecules is not fortuitously, but relies on the contribution of these markers to TEX biogenesis including loading and TEX target interactions. In addition, CIC markers contribute to TEX binding- and uptake-promoted activation of signaling cascades, transcription initiation, and translational control. Our point of view will be outlined for pancreas and colon CIC highly expressing CD44v6, Tspan8, EPCAM, claudin7, and LGR5, which distinctly but coordinately contribute to tumor progression. Despite overwhelming progress in unraveling the metastatic cascade and the multiple tasks taken over by CIC-TEX, there remains a considerable gap in linking CIC biomarkers, TEX, and TEX-initiated target modulation with metastasis. We will try to outline possible bridges, which could allow depicting pathways for new and expectedly powerful therapeutic interference with tumor progression.

Multiplexed profiling of single-cell extracellular vesicles secretion

Extracellular vesicles (EVs) are important intercellular mediators regulating health and diseases. Conventional methods for EV surface marker profiling, which was based on population measurements, masked the cell-to-cell heterogeneity in the quantity and phenotypes of EV secretion. Herein, by using spatially patterned antibody barcodes, we realized multiplexed profiling of single-cell EV secretion from more than 1,000 single cells simultaneously. Applying this platform to profile human oral squamous cell carcinoma (OSCC) cell lines led to a deep understanding of previously undifferentiated single-cell heterogeneity underlying EV secretion. Notably, we observed that the decrement of certain EV phenotypes (e.g., CD63+EV) was associated with the invasive feature of both OSCC cell lines and primary OSCC cells. We also realized multiplexed detection of EV secretion and cytokines secretion simultaneously from the same single cells to investigate the multidimensional spectrum of cellular communications, from which we resolved tiered functional subgroups with distinct secretion profiles by visualized clustering and principal component analysis. In particular, we found that different cell subgroups dominated EV secretion and cytokine secretion. The technology introduced here enables a comprehensive evaluation of EV secretion heterogeneity at single-cell level, which may become an indispensable tool to complement current single-cell analysis and EV research.

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.

Downregulation of RGMA by HIF-1A/miR-210-3p axis promotes cell proliferation in oral squamous cell carcinoma

Repulsive guidance molecules comprise a group of proteins that play an important role in carcinogenesis through interactions with their receptors, but their function in oral squamous cell carcinoma (OSCC) is unclear. Here, we investigated the potential role of the RGM family members in oral cancer pathogenesis. Our study showed that only RGMA was significantly downregulated in the OSCC tissues analyzed by TCGA and validated this finding in OSCC cells. The decreased expression of RGMA was strongly associated with the T stage and with poor prognosis. The ectopic expression of RGMA significantly inhibited the proliferation of OSCC cells both in vitro and in vivo. Moreover, we confirmed that RGMA was a target of miR-210-3p in OSCC and miR-210-3p overexpression contributed to the acceleration of OSCC growth. Further experiments revealed that HIF1A specifically interacted with the promoter of miR-210-3p and enhanced its expression. In summary, our research indicates that RGMA is regulated by the HIF1A/miR-210-3p axis and inhibits OSCC cell proliferation; thus, in the future, the development of therapies that target the HIF1A/miR-210-3p/RGMA axis may aid in the treatment of aggressive cancers.