Downregulation of the Rho GTPase signaling pathway is involved in the microRNA-138-mediated inhibition of cell migration and invasion in tongue squamous cell carcinoma

Pyruvate kinase M2 deregulation enhances the metastatic potential of tongue squamous cell carcinoma

Pyruvate kinase M2 (PKM2) has been verified to correlate with the prognosis of many types of cancer. However, its role in the development and metastasis of tongue squamous cell carcinoma (TSCC) remains unclear. The immunohistochemistry (IHC) results confirmed that PKM2 is overexpressed in patients with TSCC. PKM2 up-regulation was related to lymph node metastasis and associated with reduced overall survival. According to the microarray analysis and Western blots, PKM2 expression was up-regulated in TSCC cells with enhanced metastatic potential. PKM2 knockdown inhibited cell migration and invasion, reduced SOD2 (manganese superoxide dismutase) activity and the intracellular H₂O₂ level, and inhibited tumour growth and lung metastasis in vivo. PKM2 overexpression promoted cell migration and invasion, and increased SOD2 activity and the intracellular H₂O₂ level. Moreover, miR-138 directly targeted PKM2 and inhibited PKM2 expression. Thus, PKM2 deregulation plays an important role in TSCC and may serve as a biomarker of metastatic potential or as a therapeutic target in patients with TSCC. PKM2, a miR-138 target gene, enhances the metastatic potential of TSCC through the SOD2-H₂O₂ pathway.

ANGPTL1 attenuates colorectal cancer metastasis by up-regulating microRNA-138

Background

Angiopoietin-like protein 1 (ANGPTL1) has been reported to suppress migration and invasion in lung and breast cancer, acting as a novel tumor suppressor candidate. Nevertheless, its effects on colorectal cancer (CRC) remain poorly defined. In this study, we aim to demonstrate the biological function of ANGPTL1 in CRC cells.

Methods

We explored ANGPTL1 mRNA expression in human CRC tissues and its association with prognosis. CRC cell lines overexpressing ANGPTL1 or with ANGPTL1 knocked down were constructed and analyzed for changes in proliferation, colony formation, migration and invasion. ANGPTL1-regulated microRNAs were analyzed, and microRNA inhibitor and mimics were used to explore the role of microRNA in ANGPTL1-associated biological function.

Results

ANGPTL1 mRNA expression was down-regulated in CRC tissues, and high ANGPTL1 expression predicted better survival in CRC patients. ANGPTL1 overexpression resulted in suppressed migration and invasion in vitro, and it prolonged overall survival in mouse models. By contrast, its down-regulation enhanced migration and invasion of CRC cells. MicroRNA-138 expression was positively correlated with ANGPTL1 mRNA level in CRC tissues and up-regulated by ANGPTL1 in CRC cells. In addition, the microRNA-138 inhibitor or mimics could reverse or promote the ANGPTL1-mediated inhibition of the migratory capacity of CRC cells, respectively.

Conclusions

This study is the first to demonstrate the biological function of ANGPTL1 in CRC cells. ANGPTL1 expression was down-regulated in CRC tissues and inversely correlated with poor survival. ANGPTL1 repressed migration and invasion of CRC cells, and microRNA-138 was involved in this process.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0548-7) contains supplementary material, which is available to authorized users.

microRNAs: Emerging players in oral cancers and inflammatory disorders

Association of oral diseases and disorders with altered microRNA profiles is firmly recognized. These evidences support the potential use of microRNAs as therapeutic tools for diagnosis, prognosis, and treatment of various diseases. In this review, we highlight the association of altered microRNA signatures in oral cancers and oral inflammatory diseases. Advances in our ability to detect microRNAs in human sera and saliva further highlight their clinical value as potential biomarkers. We have discussed key mechanisms underlying microRNA dysregulation in pathological conditions. The use of microRNAs in diagnostics and their potential therapeutic value in the treatment of oral diseases are reviewed.

MiR-138: A promising therapeutic target for cancer

MicroRNAs are small noncoding RNAs which regulate gene expressions at post-transcriptional level by binding to the 3'-untranslated region of target messenger RNAs. Growing evidences highlight their pivotal roles in various biological processes of human cancers. Among them, miR-138, generating from two primary transcripts, pri-miR-138-1 and pri-miR-138-2, expresses aberrantly in different cancers and is extensively studied in cancer network. Importantly, studies have shown that miR-138 acts as a tumor suppressor by targeting many target genes, which are related to proliferation, apoptosis, invasion, and migration. Additionally, some researches also discover that miR-138 can sensitize tumors to chemotherapies. In this review, we summarize the expression of miR-138 on regulatory mechanisms and tumor biological processes, which will establish molecular basis on the usage of miR-138 in clinical applications in the future.

Impact of microRNA dynamics on cancer hallmarks: An oral cancer scenario

MicroRNAs are endogenous small noncoding RNAs that negatively regulate gene expression at posttranscriptional level. The discovery of microRNAs has identified a new layer of gene regulation mechanisms, which play a pivotal role in development as well as in various cellular processes, such as proliferation, differentiation, cell growth, and cell death. Deregulated microRNA expression favors acquisition of cancer hallmark traits as well as transforms the tumor microenvironment, leading to tumor development and progression. Many recent studies have revealed altered expression of microRNAs in oral carcinoma with several microRNAs shown to have key biological role in tumorigenesis functioning either as tumor suppressors or as tumor promoters. MicroRNA expression levels correlate with clinicopathological variables and have a diagnostic and prognostic value in oral carcinoma. For these reasons, microRNA has been a hot topic in oral cancer research for the last few years. In this review, we attempt to summarize the present understanding of microRNA deregulation in oral carcinoma, their role in acquiring cancer hallmarks, and their potential diagnostic and prognostic value for oral cancer management.

Gene expression of miRNA-138 and cyclin D1 in oral lichen planus

OBJECTIVES

This study aimed to evaluate microRNA-138 (miR-138) gene expression and its target cyclin D1 (CCND1) gene and protein expression in oral lichen planus (OLP) mucosa in an attempt to investigate their possible roles in OLP immunopathogenesis.

METHODS

Sixty oral biopsy specimens were harvested from 30 healthy subjects and 30 OLP patients, subdivided into reticular, atrophic, and erosive groups (n = 10 each). Samples were subjected to quantitative real-time polymerase chain reaction analysis for quantification of miR-138 and CCND1 relative gene expression and immunohistochemical analysis to determine CCND1 protein expression.

RESULTS

Samples from OLP patients had a significant underexpression of miR-138 gene and overexpression of CCND1 at both gene and protein levels compared to normal mucosa samples. The lowest levels of miR-138 expression were observed in atrophic and erosive OLP compared to reticular OLP, and the highest levels of CCND1 gene and protein expression were in atrophic OLP. An inverse correlation was demonstrated between the miR-138 expression and both CCND1 gene and protein expression in OLP patients. A significant positive correlation between CCND1 gene and protein expression was also observed.

CONCLUSION

Downregulation of miR-138 increases the gene and protein expression of its potential target CCND1 in OLP mucosa which might have a pivotal role in the disease pathogenesis.

CLINICAL RELEVANCE

This research implied that miR-138 may have a role in identification of symptomatic OLP lesions. MiR-138 might be considered as a potential tool in future OLP molecular therapy.

HCV core inhibits hepatocellular carcinoma cell replicative senescence through downregulating microRNA-138 expression

Hepatitis C virus (HCV) infection is a major cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma (HCC). HCV core protein is considered as a positive regulator of telomerase activity. In this study, we focused on the deregulated microRNA-138 (miR-138) in HCV-associated HCC. Differential expression of miR-138 was determined by TaqMan quantitative real-time PCR. The target gene of miR-138 was verified by luciferase reporter assay, quantitative real-time PCR, and Western blotting. Moreover, three assays based on telomerase activity, cell proliferation, and senescence-associated β-galactosidase activity were performed. The correlation analysis revealed a significantly negative correlation between miR-138 and telomerase reverse transcriptase (TERT) mRNA expression in HCC. Further, we showed that mature HCV core protein of 173 amino acids, but not full-length form of 191 amino acids, suppressed miR-138 expression. TERT was verified as a direct target of miR-138 in HCC cells. Furthermore, TERT-targeting miR-138 supplementation can prevent HCV core protein from repressing HCC cell replicative senescence. Collectively, HCV core protein can enhance TERT protein expression through downregulating TERT-targeting miR-138 expression, which in turn inhibits HCC cell replicative senescence. This study may further help our understanding on the pathogenic mechanisms of HCV core protein in HCV-associated HCC development. KEY MESSAGE: miR-138 is downregulated in HCV-associated HCC. Mature HCV core protein plays a pathogenic role in suppressing miR-138 expression. Telomerase reverse transcriptase represents a direct target of miR-138 in HCC cells. miR-138 promotes HCC cell senescence, suggesting potential for HCC treatment.

Dysregulation of AKT1, a miR-138 target gene, is involved in the migration and invasion of tongue squamous cell carcinoma

BACKGROUND

AKT1, also known as PKBα, is abnormally expressed in various malignancies. In this study, we aimed to evaluate the role of AKT1 in the tongue squamous cell carcinoma (TSCC) and further clarify the mechanisms of AKT1 in the migration and invasion of TSCC.

METHODS

At first, immunohistochemistry (IHC) was conducted to detect the expression of AKT1 in TSCC. Then, we determined the role of AKT1 in the migration and invasion of TSCC and further investigated whether AKT1 was the target gene of miR-138 using dual luciferase reporter assays and Western blot.

RESULTS

Immunohistochemistry results suggested that AKT1 dysregulation was a frequent event in TSCC, and upregulation of AKT1 was correlated with lymph node metastasis and associated with reduced overall survival. UM1 cells with higher migratory and invasive abilities had more robust AKT1 protein expression than UM2 cells with lower migratory and invasive abilities. The migration and invasion abilities were inhibited in UM1 cells upon AKT1 knockdown, meanwhile resulted in a decline of metastasis-related proteins (vimentin, slug, and pERK1/2), and upregulation of E-cadherin. Luciferase assays revealed that AKT1 was directly targeted by miR-138, and ectopic transfection of miR-138 reduced the expression of AKT1 protein.

CONCLUSIONS

Our results confirm that upregulation of AKT1, a miR-138 target gene, is a frequent event in TSCC and contributes to the aggressive behaviors and poor prognosis of TSCC.

Prognostic microRNAs modulate the RHO adhesion pathway: A potential therapeutic target in undifferentiated pleomorphic sarcomas

A common and aggressive subtype of soft-tissue sarcoma, undifferentiated pleomorphic sarcoma (UPS) was examined to determine the role of micro-RNAs (miRNAs) in modulating distant metastasis. Following histopathologic review, 110 fresh frozen clinically annotated UPS samples were divided into two independent cohorts for Training (42 patients), and Validation (68 patients) analyses. Global miRNA profiling on the Training Set and functional analysis in vitro suggested that miRNA-138 and its downstream RHO-ROCK cell adhesion pathway was a convergent target of miRNAs associated with the development of metastasis. A six-miRNA signature set prognostic of distant metastasis-free survival (DMFS) was developed from Training Set miRNA expression values. Using the six-miRNA signature, patients were successfully categorized into high- and low-risk groups for DMFS in an independent Validation Set, with a hazard ratio (HR) of 2.25 (p = 0.048). After adjusting for other known prognostic variables such as age, gender, tumor grade, size, depth, and treatment with radiotherapy, the six-miRNA signature retained prognostic value with a HR of 3.46 (p < 0.001). A prognostic miRNA biomarker for clinical validation was thus identified along with a functional pathway that modulates UPS metastatic phenotype.

Tumour-suppressor microRNAs regulate ovarian cancer cell physical properties and invasive behaviour

The activities of pathways that regulate malignant transformation can be influenced by microRNAs (miRs). Recently, we showed that increased expression of five tumour-suppressor miRs, miR-508-3p, miR-508-5p, miR-509-3p, miR-509-5p and miR-130b-3p, correlate with improved clinical outcomes in human ovarian cancer patients, and that miR-509-3p attenuates invasion of ovarian cancer cell lines. Here, we investigate the mechanism underlying this reduced invasive potential by assessing the impact of these five miRs on the physical properties of cells. Human ovarian cancer cells (HEYA8, OVCAR8) that are transfected with miR mimics representing these five miRs exhibit decreased invasion through collagen matrices, increased cell size and reduced deformability as measured by microfiltration and microfluidic assays. To understand the molecular basis of altered invasion and deformability induced by these miRs, we use predicted and validated mRNA targets that encode structural and signalling proteins that regulate cell mechanical properties. Combined with analysis of gene transcripts by real-time PCR and image analysis of F-actin in single cells, our results suggest that these tumour-suppressor miRs may alter cell physical properties by regulating the actin cytoskeleton. Our findings provide biophysical insights into how tumour-suppressor miRs can regulate the invasive behaviour of ovarian cancer cells, and identify potential therapeutic targets that may be implicated in ovarian cancer progression.

MicroRNA-21 regulates prostaglandin E2 signaling pathway by targeting 15-hydroxyprostaglandin dehydrogenase in tongue squamous cell carcinoma

Background

Oral tongue squamous cell carcinoma (OTSCC) is one of the most aggressive forms of head and neck/oral cancer (HNOC), and is a complex disease with extensive genetic and epigenetic defects, including microRNA deregulation. Identifying the deregulation of microRNA-mRNA regulatory modules (MRMs) is crucial for understanding the role of microRNA in OTSCC.

Methods

A comprehensive bioinformatics analysis was performed to identify MRMs in HNOC by examining the correlation among differentially expressed microRNA and mRNA profiling datasets and integrating with 12 different sequence-based microRNA target prediction algorithms. Confirmation experiments were performed to further assess the correlation among MRMs using OTSCC patient samples and HNOC cell lines. Functional analyses were performed to validate one of the identified MRMs: miR-21-15-Hydroxyprostaglandin Dehydrogenase (HPGD) regulatory module.

Results

Our bioinformatics analysis revealed 53 MRMs that are deregulated in HNOC. Four high confidence MRMs were further defined by confirmation experiments using OTSCC patient samples and HNOC cell lines, including miR-21-HPGD regulatory module. HPGD is a known anti-tumorigenic effecter, and it regulates the tumorigenic actions of Prostaglandin E2 (PGE2) by converts PGE2 to its biologically inactive metabolite. Ectopic transfection of miR-21 reduced the expression of HPGD in OTSCC cell lines, and the direct targeting of the miR-21 to the HPGD mRNA was confirmed using a luciferase reporter gene assay. The PGE2-mediated upregulation of miR-21 was also confirmed which suggested the existence of a positive feed-forward loop that involves miR-21, HPGD and PGE2 in OTSCC cells that contribute to tumorigenesis.

Conclusions

We identified a number of high-confidence MRMs in OTSCC, including miR-21-HPGD regulatory module, which may play an important role in the miR-21-HPGD-PGE2 feed-forward loop that contributes to tumorigenesis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2716-0) contains supplementary material, which is available to authorized users.

miRNAs Signature in Head and Neck Squamous Cell Carcinoma Metastasis: A Literature Review

STATEMENT OF THE PROBLEM

Head and neck cancers include epithelial tumors arising in the oral cavity, pharynx, larynx, paranasal sinuses, and nasal cavity. Metastasis is a hallmark of cancer. MicroRNAs (miRNAs) are endogenous small non-coding RNAs involved in cell proliferation, development, differentiation and metastasis. It is believed that miRNA alterations correlate with initiation and progression of cancer cell proliferation or inhibition of tumorigenesis. Moreover, miRNAs have different roles in development, progression, and metastasis of head and neck squamous cell carcinoma (HNSCC). Altered expression of miRNAs could be novel molecular biomarkers for the definite diagnosis of cancer, metastatic site, cancer stage, and its progression.

PURPOSE

The purpose of this review was to provide a comprehensive literature review of the role of miRNAs in head and neck cancer metastasis.

SEARCH STRATEGY

A relevant English literature search in PubMed, ScienceDirect, and Google Scholar was performed. The keywords 'miRNA', 'head and neck', and 'cancer' were searched in title and abstract of publications; limited from 1990 to 2015. The inclusion criterion was the role of miRNAs in cancer metastasis. The exclusion criterion was the other functions of miRNAs in cancers. Out of 15221 articles, the full texts of 442 articles were retrieved and only 133 articles met the inclusion criteria.

CONCLUSION

Despite the advances in cancer treatment, the mortality rate of HNSCC is still high. The potential application of miRNAs for cancer therapy has been demonstrated in many studies; miRNAs function as either tumor suppressor or oncogene. The recognition of metastamir and their targets may lead to better understanding of HNSCC oncogenesis, and consequently, development of new therapeutic strategies which is a necessity in cancer treatment. Development of therapeutic agents based on miRNAs is a promising target.

MicroRNA-138 suppresses proliferation, invasion and glycolysis in malignant melanoma cells by targeting HIF-1α

MicroRNAs (miRs) may induce mRNA degradation or inhibit protein translation by directly binding to the 3'-untranslational region of target mRNAs. It has been reported that miR-138 is downregulated in malignant melanoma (MM) cells. However, the role of miR-138 in MM cell proliferation, invasion and energy metabolism remains unknown. These were investigated using reverse transcription-quantitative polymerase chain reaction was used to evaluate the expression of miR-138 and the mRNA expression of hypoxia-inducible factor-1α (HIF-1α), as HIF-1α serves a crucial role in glycolysis, which is important for tumor growth. In addition, western blot analysis was used to detected the protein expression of HIF-1α, while MTT and Transwell assays evaluated cell proliferation and invasion, respectively. Furthermore, glucose consumption and lactic acid production were assessed. These tests were conducted using the normal human melanocyte cell line HM and the MM cell line WM451, which was transfected variously with scramble miR mimics, miR-138 mimics, miR-138 inhibitor, non-specific small interfering (si)RNA, HIF-1α siRNA, or co-transfected with miR-138 mimics and pc-DNA3.1(+)-HIF-1α plasmid. The results showed that miR-138 was significantly downregulated in MM WM451 cells compared to a normal melanocyte cell line HM. Overexpression of miR-138 significantly inhibited the proliferation and invasion of WM451 cells. These effects were similar to those induced by the siRNA-mediated knockdown of HIF-1α, a direct target of miR-138. Further investigation found that miR-138 negatively regulated the protein expression of HIF-1α in WM451 cells. Moreover, upregulation of miR-138 notably inhibited the glycolysis level, as demonstrated by reduced glucose consumption and lactic acid production, which could be reversed by the overexpression of HIF-1α. In summary, the present study demonstrated that miR-138 is able to inhibit proliferation, invasion and glycolysis in MM cells, potentially by directly targeting HIF-1α.

MicroRNAs are involved in cadmium tolerance in Daphnia pulex

Daphnia can develop tolerance to cadmium (Cd) after multi-generational exposures. Until now, Cd tolerance in this crustacean was thought to be mainly due to its sequestration via induction of metallothioneins (MTs). Our research supports other studies showing microRNAs (miRNAs) also play a role in this enhanced tolerance. We induced Cd tolerance in Daphnia pulex after exposing them for 25 generations and examined the maintenance of enhanced Cd tolerance under a Cd-free environment for an additional three generations. Acute Cd tolerance as well as long-term effects on population dynamics were measured in selected generations via 48h LC50 tests and 21 d reproductive tests, respectively. Cd tolerance was associated with differential expression of 10 miRNAs (miR-2, miR-33, miR-92, miR-96, miR-153, miR-252, miR-279, miR-283, miR-305 and miR-615). Pathway analysis revealed these miRNAs might increase Cd tolerance by suppressing cellular growth and proliferation by GTPase and cuticle protein pathways, which switch cellular energy allocation to detoxification processes. Moreover, we found increased Cd tolerance is related with induction of MT3 and MT4 and a subsequent downregulation of MT1 and MT3 expression when animals are moved to a Cd-free environment. This is the first study linking aquatic invertebrate miRNAs with induced tolerance to environmental stressors.

No Significant Effect of ASAP1 Gene Variants on the Susceptibility to Tuberculosis in Chinese Population

Recent studies have proposed that the ASAP1 gene participates in regulating the adaptive immune response to Mycobacterium tuberculosis infection. A GWAS study has reported that ASAP1 polymorphisms (rs4733781 and rs10956514) were associated with the risk of tuberculosis (TB) in Russians. But due to population heterogeneity, different races would have different causative polymorphisms, and the aim of this study was to investigate the association between single nucleotide polymorphisms (SNPs) of the ASAP1 gene and TB risk in Chinese population.A total of 7 SNPs in the ASAP1 gene were genotyped in 1115 Western Chinese Han and 914 Tibetan population using an improved multiplex ligation detection reaction (iMLDR) method. The associations of SNPs with TB risk and clinical phenotypes were determined based on the distributions of allelic frequencies and different genetic models. A meta-analysis was carried out to further assess the relationship between ASAP1 polymorphism and TB risk.Statistical comparisons of cases and controls after correction for multiple testing did not yield any significant associations with the risk of TB via analyses of a single locus, haplotype, and subgroup differences. Meta-analysis showed no evidence supporting association between rs10956514 and overall risk for TB. Subsequent analysis referring to the genotypes of SNPs in relationship to clinical phenotypes identified that rs4236749 was associated with different serum C-reactive protein levels, suggesting a role of this locus in influencing the inflammatory state of Western Chinese Han patients with TB.Our present data revealed that ASAP1 polymorphisms are unlikely to confer susceptibility to TB in the Western Chinese Han and Tibetan populations, which challenges the promising roles of the ASAP1 gene in the development of TB and highlights the importance of validating the association findings across ethnicities.

Suberoylanilide hydroxamic acid inhibits growth of head and neck cancer cell lines by reactivation of tumor suppressor microRNAs

BACKGROUND

microRNAs negatively regulate gene expression at the post-transcriptional level. Mounting evidence shows that miR expression is deregulated in human cancers including head and neck squamous cell carcinoma (HNSCC). Epigenetically silenced tumor suppressor miRs may be re-expressed upon treatment with histone deacetylases inhibitors. Suberoylanilide Hydroxamic Acid (SAHA) is a histone deacetylase inhibitor that is currently being investigated in clinical trials for HNSCC. We hypothesized that SAHA will re-express a set of tumor suppressor miRs and enhance the efficacy of cisplatin and radiation in HNSCC.

RESULTS

In this study, miR expression profile was utilized to identify the tumor suppressor miRs that are re-expressed following SAHA treatment in HNSCC. Our data demonstrated that two tumor suppressor miRs, miR-107 and miR-138, were significantly up-regulated in CAL27 and SCC25 cell lines, following SAHA treatment. In addition to this, treatment with SAHA in a dose dependent manner significantly inhibited the cell proliferation, cell migration, and anchorage dependent clonogenic survival in CAL27 and SCC25 cell lines, respectively. Further, the expression of several oncogenes, PKCε, HIF1β, CDK6, and RhoC were down regulated in response to SAHA treatment. Additionally, we demonstrated that the combination treatment with SAHA and a chemotherapeutic drug cisplatin caused a significant reduction of cell growth compared to the single agent treatment.

CONCLUSION

Our data indicate that SAHA treatment results in reactivation of the silenced tumor suppressor miRs. Furthermore, this study emphasizes the usefulness of this drug as a novel combination therapy for HNSCC patients.

Downregulation of Microrna-126 Contributes to Tumorigenesis of Squamous Tongue Cell Carcinoma via Targeting KRAS

BACKGROUND miR-126 has been reported to be differentially expressed in various malignancies, whereas its role in the pathogenesis of tongue squamous cell carcinoma (TSCC) remains largely unknown. MATERIAL AND METHODS In this study, we collected 21 pairs of TSCC cancerous and adjacent non-cancerous tissue samples, with which we performed real-time PCR to determine and compare the expression of 6 candidate miRNAs that are reportedly associated with tumorigenesis of TSCC, including miR-100, miR-451, miR-221, let-7a, miR-21, and miR-126. We further performed luciferase assay to validate KRAS as a target of miR-126, and conducted transfection to study the effect of miR-126 on proliferation and apoptosis of the cells. RESULTS We identified that miR-126 was significantly downregulated in the cancerous tissue samples compared with the non-cancerous control tissue samples. By using computational analysis, we identified that KRAS is a virtual target of miR-126, and such association was verified by using luciferase assay. In addition, we found that mRNA and protein expression level of KRAS was significantly higher in the tumor tissue than the control tissue samples. CONCLUSIONS The following in vitro experiment showed that both mRNA and protein KRAS expression were significantly decreased in SCC-15 cells in which miR-126 was overexpressed, in comparison with similar cells transfected with a negative control, while downregulation of miR-126 by transfecting the cells with miR-126 inhibitors significantly upregulated the mRNA and protein expression of KRAS.

CONCLUSIONS

miR-126 might be a promising diagnostic and therapeutic target in the prevention and management of TSCC patients.

Novel Insights into the Roles of Rho Kinase in Cancer

Rho-associated coiled-coil kinase (ROCK) is a major downstream effector of the small GTPase RhoA. The ROCK family, consisting of ROCK1 and ROCK2, plays a central role in the organization of the actin cytoskeleton, and is involved in a wide range of fundamental cellular functions such as contraction, adhesion, migration, proliferation, and apoptosis. Since the discovery of effective inhibitors such as fasudil and Y27632, the biological roles of ROCK have been extensively explored in numerous diseases, including cancer. Accumulating evidence supports the concept that ROCK plays important roles in tumor development and progression through regulating many key cellular functions associated with malignancy, including tumorigenicity, tumor growth, metastasis, angiogenesis, tumor cell apoptosis/survival and chemoresistance as well. This review focuses on the new advances of the most recent 5 years from the studies on the roles of ROCK in cancer development and progression; the discussion is mainly focused on the potential value of ROCK inhibitors in cancer therapy.

MicroRNA-138 Inhibits Periodontal Progenitor Differentiation under Inflammatory Conditions

Inflammatory conditions as they occur during periodontal disease often result in decreased alveolar bone levels and a loss of connective tissue homeostasis. Here we have focused on the effect of microRNA-138 (miR-138) as a potential regulator of periodontal stem cells as they affect homeostasis during inflammatory conditions. Our data indicate that miR-138 was significantly upregulated in our periodontal disease animal model. Interaction of miR-138 with a predicted targeting site on the osteocalcin (OC) promoter resulted in a 3.7-fold reduction of luciferase activity in promoter assays compared with controls; and miR-138 overexpression in periodontal progenitors significantly inhibited OC (3.4-fold), Runx2 (2.8-fold), and collagen I (2.6-fold). Moreover, treatment with inflammatory modulators such as interleukin (IL)-6 and lipopolysaccharide (LPS) resulted in a significant 2.2-fold (IL-6) or 1.9-fold (LPS) increase in miR-138 expression, while OC and Runx2 expression was significantly decreased as a result of treatment with each inflammatory mediator. Further defining the role of miR-138 in the OC-mediated control of mineralization, we demonstrated that the LPS-induced downregulation of OC expression was partially reversed after miR-138 knockdown. LPS, miR-138 mimic, and OC small interfering RNA inhibited osteoblast differentiation marker alkaline phosphatase activity, while miR-138 inhibitor and OC protein addition enhanced alkaline phosphatase activity. Supporting the role of OC as an essential modulator of osteoblast differentiation, knockdown of miR-138 or addition of OC protein partially rescued alkaline phosphatase activity in periodontal ligament (PDL) cells subjected to LPS treatment. Our data establish miR-138 inhibitor as a potential therapeutic agent for the prevention of the bone loss associated with advanced periodontal disease.

MicroRNA expression and its implications for diagnosis and therapy of tongue squamous cell carcinoma

Tongue squamous cell carcinoma (TSCC) is the most common type of oral squamous cell carcinomas and is well known for its high rate of lymph nodal metastasis. Despite the identification of many molecular mechanisms in TSCC, the number of deaths associated with TSCC increased during the past 5 years. MicroRNAs (miRNAs) are a family of small non-coding RNA molecules, which regulate gene expression by either translational inhibition or mRNA degradation. miRNAs have been proven to be key regulators of various biological and pathological processes including cell proliferation, development and tumourigenesis. Increasing evidence has demonstrated that the deregulated miRNAs are implicated in the diagnosis and treatment of TSCC. In this review, we summarized the expressions and roles of miRNAs in TSCC and comment on the potential roles of miRNAs in diagnosis, prognosis and treatment of this malignancy.

ROCK inhibitor Y-27632 inhibits the growth, migration, and invasion of Tca8113 and CAL-27 cells in tongue squamous cell carcinoma

The objective of this study is to determine the effects of Rho-associated coiled-coil containing protein kinase (ROCK) inhibitor Y-27632 on the growth, invasion, and migration of Tca8113 and CAL-27 cells in tongue squamous cell carcinoma (TSCC). The methods of the study are as follows: After being routinely cultured for 24 h, Tca8113 and CAL-27 cells were treated with Y-27632 solution. The morphological change of Y-27632-treated cells was observed under an optical microscope and an inverted microscope; MTT assay was performed to measure the optical density (OD) of cells and calculate cell growth inhibition rate; the change of apoptosis was detected by AnnexinV-FITC/PI assay; cell invasion and migration were measured by Transwell assay. The results were as follows: (1) With increasing concentration of Y-27632, cell morphology changed and cell apoptosis appeared; (2) MTT assay showed that inhibition effect of Y-27632 on Tca8113 and CAL-27 cells was enhanced with increasing concentrations and time (all P < 0.01); (3) Apoptosis showed that, compared with controls, the number of apoptosis cells in experimental groups was significantly increased (all P < 0.01). Apoptosis rate was elevated with increasing concentrations of Y-27632; (4) Transwell assay showed, after a treatment with Y-27632, the number of migrated and invaded Tca8113 and CAL-27 cells in each group was statistically different (all P < 0.01); compared with controls, the number of migrated cell in groups treated with Y-27632 was decreased and less Tca8113 and CAL-27 cells in experimental groups passed through polycarbonate membrane (all P < 0.05). The study concludes that Y-27632 can inhibit the growth, invasion, and migration of Tca8113 and CAL-27 cells, suggesting that Y-27632 may be therapeutically useful in TSCC.

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.

Inhibition of invasion and metastasis of human liver cancer HCCLM3 cells by portulacerebroside A

CONTEXT

Portulacerebroside A (PCA) is a novel cerebroside compound isolated from Portulaca oleracea L. (Portulacaceae), an edible and medicinal plant distributed in the temperate and tropical zones worldwide.

OBJECTIVE

This study investigates the effects of PCA in human liver cancer HCCLM3 cells on metastasis and invasion.

MATERIALS AND METHODS

After the cells were treated with PCA (2.5, 5, and 10 μg/ml) for 6, 12, 24, or 48 h, adhesion, transwell invasion, and scratch tests were conducted and cell functions were evaluated. Western blot and FQ-RT-PCR assays explored the mechanism of PCA-inhibited invasion and metastasis in the cells.

RESULTS

The adhesion rate of the cells was suppressed at 0.5 h (79.4 ± 1.0, 68.7 ± 1.3, and 58.1 ± 1.3%, versus 100 ± 1.5% in the control), 1 h (78.2 ± 1.2, 70.9 ± 1.6, and 55.4 ± 1.9%, versus 100 ± 1.2% in the control), and 1.5 h (71.6 ± 1.1, 62.3 ± 0.9, and 50.4 ± 0.9%, versus 100 ± 1.1% in the control). The 24 h invasion ability was decreased (356.6 ± 11.2, 204.0 ± 17.6, and 113.0 ± 9.5%, versus 443.6 ± 15.4% in the control). The migration capability was also restrained by PCA for 24 h (324.8 ± 25.4, 250.4 ± 21.0, and 126.3 ± 10.1, versus 381.6 ± 30.6 in the control) and 48 h (470.3 ± 34.3, 404.0 ± 19.7, and 201.0 ± 15.4, versus 752.0 ± 63.6 in the control). There was an increase in the mRNA and protein expression levels of TIMP-2 and nm23-H1, inhibition in the mRNA expression of MTA1, MMP-2, and MMP-9, and suppression in the protein expression of MTA1, RhoA, Rac1/Cdc42, MMP-2, but not RhoC and MMP-9.

CONCLUSION

PCA suppresses the invasion and metastasis of HCCLM3 cells possibly by modulation of the mRNA and protein expression of related parameters. This is the first study to reveal a new potential therapeutic application of PCA in antimetastatic therapy for liver cancer.

The Regulatory Role of MicroRNAs in EMT and Cancer

The epithelial to mesenchymal transition (EMT) is a powerful process in tumor invasion, metastasis, and tumorigenesis and describes the molecular reprogramming and phenotypic changes that are characterized by a transition from polarized immotile epithelial cells to motile mesenchymal cells. It is now well known that miRNAs are important regulators of malignant transformation and metastasis. The aberrant expression of the miR-200 family in cancer and its involvement in the initiation and progression of malignant transformation has been well demonstrated. The metastasis suppressive role of the miR-200 members is strongly associated with a pathologic EMT. This review describes the most recent advances regarding the influence of miRNAs in EMT and the control they exert in major signaling pathways in various cancers. The ability of the autocrine TGF-β/ZEB/miR-200 signaling regulatory network to control cell plasticity between the epithelial and mesenchymal state is further discussed. Various miRNAs are reported to directly target EMT transcription factors and components of the cell architecture, as well as miRNAs that are able to reverse the EMT process by targeting the Notch and Wnt signaling pathways. The link between cancer stem cells and EMT is also reported and the most recent developments regarding clinical trials that are currently using anti-miRNA constructs are further discussed.

Investigation of microRNA expression profiles associated with human alcoholic cardiomyopathy

OBJECTIVES

We aimed to investigate the differentially expressed microRNAs (miRNAs) and their target genes in human alcoholic cardiomyopathy (ACM).

METHODS

The expression levels of plasma miRNAs of 78 male ACM patients and 78 healthy men were detected by using the 6th-generation miRCURY™ LNA array (v.16.0). The prediction analysis for microarrays (PAM) method was used to identify the differentially expressed miRNAs. Target genes of the identified differentially expressed miRNAs were predicted using TargetScan 5.2 and Miranda. Gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to perform functional annotation and pathway enrichment analysis of target genes respectively, followed by real-time RT-PCR analysis to validate the expression changes of miRNAs.

RESULTS

Twenty-one differentially expressed miRNAs were identified. Nine differentially expressed miRNAs (hsa-miR-506, hsa-miR-1285, hsa-miR-512-3P, hsa-miR-138, hsa-miR-485-5P, hsa-miR-4262, hsa-miR-548c-3P, has-miR-548a-5P and kshv-miR-K12-1), involved in multiple functions and pathways, were selected for real-time RT-PCR confirmation. Moreover, two significantly important subpathways (neurotrophin signaling pathway and inositol phosphate metabolism) were predicted.

CONCLUSION

The screened differentially expressed miRNAs may be involved in the development of ACM. Specific miRNAs, such as miR-138, may be considered as a new target for the early diagnosis and treatment of human ACM.

Regulation of cancer metastasis by microRNAs

MicroRNAs (miRNAs) are a class of endogenous small non-coding RNAs that have been found highly conserved among species. MiRNAs are able to negatively regulate gene expression through base pairing of 3' UTRs of their target genes. Therefore, miRNAs have been shown to play an important role in regulating various cellular activities. Over the past decade, substantial evidences have been obtained to show that miRNAs are aberrantly expressed in human malignancies and could act as "OncomiRs" or "Tumor suppressor miRs". In recent years, increasing number of studies have demonstrated the involvement of miRNAs in cancer metastasis. Many studies have shown that microRNAs could directly target genes playing a central role in epithelia-mesenchymal-transition (EMT), a cellular transformation process that allows cancer cells to acquire motility and invasiveness. EMT is considered an essential step driving the early phase of cancer metastasis. This review will summarize the recent findings and characterization of miRNAs that are involved in the regulation of EMT, migration, invasion and metastasis of cancer cells. Lastly, we will discuss potential use of miRNAs as diagnostic and prognostic biomarkers as well as therapeutic targets for cancer.

RhoGTPases - A novel link between cytoskeleton organization and cisplatin resistance

For more than three decades, platinum compounds have been the first line treatment for a wide spectrum of solid tumors. Yet, cisplatin resistance is a major impediment in cancer therapy, and deciphering the mechanisms underlying chemoresistance is crucial for the development of novel therapies with enhanced efficacy. The Rho subfamily of small GTPases plays a significant role in cancer progression, and a growing body of evidence points toward the involvement of these proteins in anticancer drug resistance, including cisplatin resistance. The cycling between active and inactive states, governed by the balance between their GEFs, GAPs and GDIs, RhoGTPases, acts as molecular switches with a pivotal role in actin cytoskeleton organization. The Rho subfamily of proteins is involved in many key cellular processes including adhesion, vesicular trafficking, proliferation, survival, cell morphology and cell-matrix interactions. Although RhoA, RhoB and RhoC are highly homologous and share some upstream regulators and downstream effectors, they each have different roles in cancer progression and chemoresistance. While RhoA and RhoC are upregulated in many tumors and can stimulate transformation, RhoB appears to exhibit tumor suppressor characteristics with proapoptotic effects. In the current review, we discuss the role of Rho subfamily of proteins in cancer, and focus on their involvement in intrinsic and acquired drug resistance.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Expression, regulation and roles of miR-26a and MEG3 in tongue squamous cell carcinoma

MicroRNA miR-26a and long noncoding RNA (lncRNA) MEG3 gene have been independently reported to be tumor suppressor genes in various cancers, but neither has been previously associated with tongue squamous cell carcinoma (TSCC). We report here that miR-26a and lncRNA MEG3 gene expression were both strongly reduced in TSCC compared with levels in matched nonmalignant tissues, and combined low expression levels of both miR-26a and MEG3 emerged as an independent prognostic factor for poor clinical outcome in TSCC patients. Assays in the human TSCC cell lines SCC-15 and CAL27 showed that miR-26a targets the DNA methyltransferase 3B transcript and that its inhibition may result in the upregulation of MEG3, providing a plausible link between the observed reduction of miR-26a and MEG3 in TSCC tissue. Furthermore, the overexpression of miR-26a or MEG3 in SCC-15 and CAL27 cells inhibited cell proliferation and cell cycle progression, and promoted cell apoptosis. Considering the poor prognostic outcomes associated with reduced miR-26a and MEG3, our findings imply that these factors likely play important antitumor effects in TSCC pathogenesis. Furthermore, they represent potential prognostic biomarkers for stratification of TSCC patients.

miR-34a inhibits migration and invasion of tongue squamous cell carcinoma via targeting MMP9 and MMP14

Background

miR-34a is an important tumor suppressor gene in various cancer types. But little is known about the dysregulation of miR-34a in tongue squamous cell carcinoma (TSCC). In this study, we investigate the expression and potential role of miR-34a in TSCC.

Methods

We evaluated miR-34a expression and its relationship with clinicopathological characters in 75 pairs of TSCC samples, and confirmed the role of miR-34a for predicting lymph node metastases from a further 15 pairs of paraffin-embedded TSCC specimens with stringent clinicopathological recruitment criteria using quantitative reverse transcription polymerase chain reaction (qRT-PCR). The effects of miR-34a on cell proliferation, migration and invasion were examined in TSCC cell lines using Cell Counting Kit-8 assay, wound healing assay and transwell assay, respectively. The effects of miR-34a on the expression of matrix metalloproteinase (MMP) 9 and 14 were detected by luciferase reporter assays and Western blot analysis. The expression of miR-34a, MMP9 and MMP14 were also confirmed in TSCC samples by in situ hybridization and immunohistochemistry.

Results

miR-34a expression in tumor tissues from TSCC patients with positive lymph node metastases was significantly lower than that with negative lymph node metastases. Overexpression of miR-34a significantly suppressed migration and invasion in TSCC cells and simultaneously inhibited the expression of MMP9 and MMP14 through targeting the coding region and the 3′untranslated region, respectively. Moreover, miR-34a expression in TSCC was inversely correlated with protein expression of MMP9 and MMP14 in the TSCC samples.

Conclusions

miR-34a plays an important role in lymph node metastases of TSCC through targeting MMP9 and MMP14 and may have potential applications in prognosis prediction and gene therapy for lymph node metastases of TSCC patients.

Crosstalk between kinases, phosphatases and miRNAs in cancer

Reversible phosphorylation of proteins, performed by kinases and phosphatases, is the major post translational protein modification in eukaryotic cells. This intracellular event represents a critical regulatory mechanism of several signaling pathways and can be related to a vast array of diseases, including cancer. Cancer research has produced increasing evidence that kinase and phosphatase activity can be compromised by mutations and also by miRNA silencing, performed by small non-coding and endogenously produced RNA molecules that lead to translational repression. miRNAs are believed to target about one-third of human mRNAs while a single miRNA may target about 200 transcripts simultaneously. Regulation of the phosphorylation balance by miRNAs has been a topic of intense research over the last years, spanning topics going as far as cancer aggressiveness and chemotherapy resistance. By addressing recent studies that have shown miRNA expression patterns as phenotypic signatures of cancers and how miRNA influence cellular processes such as apoptosis, cell cycle control, angiogenesis, inflammation and DNA repair, we discuss how kinases, phosphatases and miRNAs cooperatively act in cancer biology.

α-Solanine inhibits invasion of human prostate cancer cell by suppressing epithelial-mesenchymal transition and MMPs expression

α-Solanine, a naturally occurring steroidal glycoalkaloid found in nightshade (Solanum nigrum Linn.), was found to inhibit proliferation and induce apoptosis of tumor cells. However, the mechanism involved in suppression of cancer cell metastasis by α-solanine remains unclear. This study investigates the suppression mechanism of α-solanine on motility of the human prostate cancer cell PC-3. Results show that α-solanine reduces the viability of PC-3 cells. When treated with non-toxic doses of α-solanine, cell invasion is markedly suppressed by α-solanine. α-Solanine also significantly elevates epithelial marker E-cadherin expression, while it concomitantly decreases mesenchymal marker vimentin expression, suggesting it suppresses epithelial-mesenchymal transition (EMT). α-Solanine reduces the mRNA level of matrix metalloproteinase-2 (MMP-2), MMP-9 and extracellular inducer of matrix metalloproteinase (EMMPRIN), but increases the expression of reversion-inducing cysteine-rich protein with kazal motifs (RECK), and tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2. Immunoblotting assays indicate α-solanine is effective in suppressing the phosphorylation of phosphatidylinositide-3 kinase (PI3K), Akt and ERK. Moreover, α-solanine downregulates oncogenic microRNA-21 (miR-21) and upregulates tumor suppressor miR-138 expression. Taken together, the results suggest that inhibition of PC-3 cell invasion by α-solanine may be, at least in part, through blocking EMT and MMPs expression. α-Solanine also reduces ERK and PI3K/Akt signaling pathways and regulates expression of miR-21 and miR-138. These findings suggest an attractive therapeutic potential of α-solanine for suppressing invasion of prostate cancer cell.

miR-29b suppresses proliferation, migration, and invasion of tongue squamous cell carcinoma through PTEN-AKT signaling pathway by targeting Sp1

OBJECTIVES

miR-29b has been implicated in various cancers. However, the role of miR-29b in tongue squamous cell carcinoma (TSCC) remains unclear. This study aimed to investigate the role of miR-29b in TSCC progression.

MATERIALS AND METHODS

The expression of miR-29b was analyzed in TSCC tissues and cells. Functional studies were performed in TSCC cells. Real time-PCR, Western blot, cell proliferation, transwell, and dual luciferase reporter assays were performed according to standard procedures.

RESULTS

miR-29b was significantly decreased in TSCC specimens and cell lines compared with corresponding normal counterparts. Overexpression of miR-29b significantly inhibited the proliferation, migration, invasion, and cell-cycle progression of TSCC cells, and promoted apoptosis. Moreover, miR-29b targeted the 3' untranslated region of the Sp1 transcript and resulted in the deregulation of Sp1. The inhibition of Sp1 by miR-29b subsequently resulted in the upregulation of PTEN, leading to a decline of phosphorylated AKT. Knockdown of Sp1 in TSCC cell lines mimicked the effects of miR-29b overexpression. In addition, the expression of miR-29b was inversely correlated with Sp1 and positively correlated with the PTEN in TSCC specimens.

CONCLUSION

miR-29b functions as a tumor suppressor in TSCC, and the miR-29b/Sp1/PTEN/AKT axis might represent a potential therapeutic target for TSCC intervention.

MiR-138 induces renal carcinoma cell senescence by targeting EZH2 and is downregulated in human clear cell renal cell carcinoma

MiR-138 has been shown to be downregulated in various cancers, including head and neck squamous cell carcinoma (HNSCC) and clear cell renal carcinoma (ccRCC). In the present study, we aimed to reveal the mechanism of miR-138 induction of senescence in renal carcinoma cells and identify its specific target genes. We used qRT-PCR to analyze miR-138 expression levels in renal carcinoma cell lines and ccRCC samples. The activity of β-galactosidase was measured for functional analysis after miR-138 mimic transfection. To identify the targets of miR-138, we used three types of target prediction software to determine three candidate target genes. Furthermore, a 3'UTR luciferase assay was performed. Western blotting was used to detect the protein expression levels of candidate target genes. Additionally, knockdown of EZH2 by its siRNA was performed. The expression of miR-138 was downregulated in RCC cells lines and in tumor samples compared with their controls. Transfection of miR-138 mimic induced SN-12 cell senescence, decreased the protein expression of EZH2, and increased the protein expression of P16. Furthermore, miR-138 decreased the 3'UTR luciferase activity of EZH2. The knockdown of EZH2 by siRNA induced SN-12 cell senescence, decreased the protein expression level of EZH2, and increased the protein expression of P16. MiR-138 is a tumor-suppressor miRNA in ccRCC that induces SN-12 cell senescence by downregulating EZH2 expression and upregulating P16 expression.

Post-transcriptional regulation of the tumor suppressor miR-139-5p and a network of miR-139-5p-mediated mRNA interactions in colorectal cancer

MicroRNAs play key roles in many biological processes, and are frequently dysregulated in tumor cells. However, there are few studies on how microRNAs are dysregulated. miR-139-5p, an important tumor suppressor, is often underexpressed in gastrointestinal cancer cells. Here, we describe post-transcriptional regulation of this intronic microRNA in human colorectal cancer. miR-139-5p is expressed independently of its overexpressed host gene PDE2A in colorectal cancer tissues and cell lines. The miR-139-5p target genes IGF1R, ROCK2 and RAP1B exert regulatory effects on the miR-139-5p expression level, relying on their ability to compete for miR-139-5p binding. These overexpressed target genes also regulate each others' protein levels through 3'-UTRs, thus regulating tumor cell growth and motility properties. Our study provides a mechanistic, experimentally validated rationale for intronic microRNA dysregulation in colorectal cancer, revealing novel oncogenic roles of IGF1R, ROCK2 and RAP1B 3'-UTRs.

Clinical significance of microRNA 138 and cyclin D3 in hepatocellular carcinoma

BACKGROUND

MicroRNA 138 (miR-138) is recently shown to inhibit tumor growth and block cell cycle arrest of hepatocellular carcinoma (HCC) by targeting cyclin D3 (CCND3). The aim of this study was to investigate the clinical significance of miR-138 and CCND3 in human HCC, which remains unclear.

METHODS

Quantitative real-time polymerase chain reaction analysis was performed to detect the expression levels of miR-138 and CCND3 messenger RNA (mRNA) in 180 self-pairs of HCC and noncancerous liver tissues.

RESULTS

Compared with noncancerous liver tissues, the expression levels of miR-138 in HCC tissues were significantly downregulated (P < 0.001), whereas the expression levels of CCND3 mRNA in HCC tissues were significantly upregulated (P < 0.001). There was a negative correlation between miR-138 and CCND3 mRNA expression in HCC tissues (r = -0.56, P = 0.02). Additionally, statistical analysis showed that the combined miR 138 downregulation and CCND3 upregulation (miR-138-low-CCND3-high) was significantly associated with the advanced tumor-node-metastasis stage (P = 0.008) and the presence of portal vein invasion (P = 0.008) and lymph node metastasis (P = 0.01). More importantly, a significant trend was identified between the combined expression of miR-138-low-CCND3-high in HCC and worsening clinical prognosis. Multivariate survival analysis further recognized miR-138-low-CCND3-high expression as an independent prognostic factor for patients with HCC.

CONCLUSIONS

Our data suggest that the combined expression of miR-138 and its direct target CCND3 may be correlated with significant characteristics of HCC. MiR-138 downregulation and CCND3 upregulation maybe concurrently associated with prognosis in patients with HCC.

Down regulation of RhoC by microRNA-138 results in de-activation of FAK, Src and Erk1/2 signaling pathway in head and neck squamous cell carcinoma

OBJECTIVE

RhoC a pro-metastatic oncogene is constitutively active in many head and neck squamous cell carcinomas. MicroRNA-138 which possesses a documented tumor suppressor function can bind to the 3'UTR of RhoC mRNA and inhibit its activity. We hypothesize that miR-138 can inhibit the function of RhoC and consequently the activation of downstream target molecules involve in the signaling cascade. For this reason we investigated the role of miR-138 in HNSCC.

METHODS

In vitro studies were carried out to evaluate the role of miR-138 in HNSCC cell lines and in primary tumors obtained from HNSCC patients. Real time RT-PCR, Western blot, cell motility, invasion and colony formation assays were performed according to standard procedures.

RESULTS

Data obtained by G-LISA and real time PCR shows an inverse correlation between RhoC expression and miR-138 in HNSCC cell lines. Additionally, we obtained a similar pattern of RhoC and miR-138 expression in primary tumors from HNSCC patients. Over expression of miR-138 in HNSCC lines showed down regulation of RhoC, as well as a decrease in cell motility, invasion colony and stress fiber formation. Furthermore, a significant down regulation was observed for FAK, Src and Erk(1/2) upon miR-138 overexpression.

CONCLUSION

These findings strongly suggest that the inhibition of RhoC can be achieved by over expressing miR-138, which further attenuates the downstream signaling cascade leading to cancer progression and survival. Moreover, this study for the first time shows that down regulation of FAK, Src and Erk(1/2) by miR-138 overexpression is due to inhibition of RhoC in HNSCC.

Multiple tumor suppressor microRNAs regulate telomerase and TCF7, an important transcriptional regulator of the Wnt pathway

The human TERT (hTERT) gene encodes the telomerase catalytic subunit which plays a role in telomerase regulation. Telomerase is activated in more than 90% of all human malignancies and understanding how telomerase is regulated is necessary for implementation of successful anti-cancer therapies. microRNAs (miRNAs) are important regulators of gene expression in eukaryotic cells but evidence of their role in telomerase regulation has not been documented. To determine whether hTERT activity is regulated by multiple miRNAs, eight miRNAs which have putative binding sites in the hTERT 3'UTR together with miR-138-5p were evaluated in luciferase assays with a reporter containing the hTERT 3'UTR. Six miRNAs (let-7g*, miR-133a, miR-138-5p, miR-342-5p, miR-491-5p, and miR-541-3p) specifically inhibited the expression of the reporter luciferase-driven constructs and let-7g*, miR-133a, miR-138-5p, and miR-491-5p also downregulated endogenous telomerase activity in cells. Moreover, all six miRNAs significantly inhibited cell proliferation. miRNAs (miR-133a, miR-138-5p, 342-5p, 491-5p, 541-3p) also have predicted binding sites within the 3'UTR of three genes involved in Wnt signaling (TCF7, MSI1, and PAX5). These miRNAs inhibited the expression of the luciferase reporter constructs containing 3'UTRs of these genes and downregulated protein expression of the TCF7 transcription factor, which mediates the canonical Wnt pathway. Together, these results suggest the existence of a miRNA regulatory network involving the hTERT and Wnt pathway.

MicroRNA-99 family members suppress Homeobox A1 expression in epithelial cells

The miR-99 family is one of the evolutionarily most ancient microRNA families, and it plays a critical role in developmental timing and the maintenance of tissue identity. Recent studies, including reports from our group, suggested that the miR-99 family regulates various physiological processes in adult tissues, such as dermal wound healing, and a number of disease processes, including cancer. By combining 5 independent genome-wide expression profiling experiments, we identified a panel of 266 unique transcripts that were down-regulated in epithelial cells transfected with miR-99 family members. A comprehensive bioinformatics analysis using 12 different sequence-based microRNA target prediction algorithms revealed that 81 out of these 266 down-regulated transcripts are potential direct targets for the miR-99 family. Confirmation experiments and functional analyses were performed to further assess 6 selected miR-99 target genes, including mammalian Target of rapamycin (mTOR), Homeobox A1 (HOXA1), CTD small phosphatase-like (CTDSPL), N-myristoyltransferase 1 (NMT1), Transmembrane protein 30A (TMEM30A), and SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A member 5 (SMARCA5). HOXA1 is a known proto-oncogene, and it also plays an important role in embryonic development. The direct targeting of the miR-99 family to two candidate binding sequences located in the HOXA1 mRNA was confirmed using a luciferase reporter gene assay and a ribonucleoprotein-immunoprecipitation (RIP-IP) assay. Ectopic transfection of miR-99 family reduced the expression of HOXA1, which, in consequence, down-regulated the expression of its downstream gene (i.e., Bcl-2) and led to reduced proliferation and cell migration, as well as enhanced apoptosis. In summary, we identified a number of high-confidence miR-99 family target genes, including proto-oncogene HOXA1, which may play an important role in regulating epithelial cell proliferation and migration during physiological disease processes, such as dermal wound healing and tumorigenesis.

MiR-138 downregulates miRNA processing in HeLa cells by targeting RMND5A and decreasing Exportin-5 stability

MicroRNAs (miRNAs) are a class of non-coding small RNAs that consist of ∼22 nt and are involved in several biological processes by regulating target gene expression. MiR-138 has many biological functions and is often downregulated in cancers. Our results showed that overexpression of miR-138 downregulated target RMND5A (required for meiotic nuclear division 5 homolog A) and reduced Exportin-5 stability, which results in decreased levels of pre-miRNA nuclear export in HeLa cells. We also found that miR-138 could significantly inhibit HeLa cell migration by targeting RMND5A. Our study therefore identifies miR-138–RMND5A–Exportin-5 as a previously unknown miRNA processing regulatory pathway in HeLa cells.

MicroRNA aberrances in head and neck cancer: pathogenetic and clinical significance

PURPOSE OF REVIEW

MicroRNAs (miRNAs) play crucial roles in modulating the neoplastic process of cancers including head and neck squamous cell carcinoma (HNSCC). miRNAs modulate pathogenesis by inhibiting target genes. Understanding how aberrant miRNAs are involved in HNSCC pathogenesis should help to validate potential clinical applications that target these entities.

RECENT FINDINGS

miR-21, miR-31, miR-504 and miR-10b are important oncogenic miRNAs that are involved in HNSCC and target tumour suppressor genes. The tumour suppressor roles of the let-7 family, the miR-99 family, miR-107, miR-133a, miR-137, miR-138 and miR-375 with respect to their targeting of oncogenes are unequivocal and have been confirmed by many studies. In addition, miR-21, let-7, miR-107, miR-138 and miR-200c seem to play complicated roles in regulating stemness or the epithelial-mesenchymal transition of tumour cells. The clinical implications of these tumour-associated miRNAs are generally in agreement with their functional roles.

SUMMARY

A number of pathways that become disregulated by aberrant miRNAs have been identified specifically for HNSCC. Analysis of these networks and their therapeutic interception might facilitate the prediction of disease status and help with the design of therapeutic trials.

Distinctive microRNA expression signatures in proton-irradiated mice

Proton particles comprise the most abundant ionizing radiation (IR) in outer space. These high energy particles are known to cause frequent double- and single-stranded DNA lesions that can lead to cancer and tumor formation. Understanding the mechanism of cellular response to proton-derived IR is vital for determining health risks to astronauts during space missions. Our understanding of the consequences of these high energy charged particles on microRNA (miRNA) regulation is still in infancy. miRNAs are non-coding, single-stranded RNAs of ~22 nucleotides that constitute a novel class of gene regulators. They regulate diverse biological processes, and each miRNA can control hundreds of gene targets. To investigate the effect of proton radiation on these master regulators, we examined the miRNA expression in selected mice organs that had been exposed to whole-body proton irradiation (2 Gy), and compared this to control mice (0 Gy exposure). RNA was isolated from three tissues (testis, brain, and liver) from treated and control mice and subjected to high-throughput small RNA sequencing. Bioinformatics analysis of small RNA sequencing data revealed dysregulation of (p < 0.05; 20 up- and 10 down-regulated) 14 mouse testis, 8 liver, and 8 brain miRNAs. The statistically significant and unique miRNA expression pattern found among three different proton-treated mouse tissues indicates a tissue-specific response to proton radiation. In addition to known miRNAs, sequencing revealed differential expression of 11 miRNAs in proton-irradiated mice that have not been previously reported in association with radiation exposure and cancer. The dysregulation of miRNAs on exposure to proton radiation suggest a possible mechanism of proton particles involvement in the onset of cell tumorgenesis. In summary, we have established that specific miRNAs are vulnerable to proton radiation, that such differential expression profile may depend upon the tissue, and that there are more miRNAs affected by proton radiation than have been previously observed.

MicroRNA-99 family targets AKT/mTOR signaling pathway in dermal wound healing

Recent studies suggest that microRNAs play important roles in dermal wound healing and microRNA deregulation has been linked with impaired wound repair. Here, using a mouse experimental wound healing model, we identified a panel of 63 differentially expressed microRNAs during dermal wound healing, including members of miR-99 family (miR-99a, miR-99b, miR-100). We further demonstrated that miR-99 family members regulate cell proliferation, cell migration, and AKT/mTOR signaling. Combined experimental and bioinformatics analyses revealed that miR-99 family members regulate AKT/mTOR signaling by targeting multiple genes, including known target genes (e.g., IGF1R, mTOR) and a new target (AKT1). The effects of miR-99 family members on the expression of IGF1R, mTOR and AKT1 were validated at both the mRNA and protein levels. Two adjacent miR-99 family targeting sites were identified in the 3′-UTR of the AKT1 mRNA. The direct interaction of miR-100 with these targeting sites was confirmed using luciferase reporter assays. The microRNA-100-directed recruitment of AKT1 mRNA to the RNAi-induced silencing complex (RISC) was confirmed by a ribonucleoprotein-IP assay. In summary, we identified a panel of differentially expressed microRNAs which may play important roles in wound healing. We provide evidence that miR-99 family members contribute to wound healing by regulating the AKT/mTOR signaling.

Suppression of tumorigenicity by microRNA-138 through inhibition of EZH2-CDK4/6-pRb-E2F1 signal loop in glioblastoma multiforme

Deregulation of microRNAs (miRNAs) is implicated in tumor progression. We attempt to identify the tumor suppressive miRNA not only down-regulated in glioblastoma multiforme (GBM) but also potent to inhibit the oncogene EZH2, and then investigate the biological function and pathophysiologic role of the candidate miRNA in GBM. In this study, we show that miRNA-138 is reduced in both GBM clinical specimens and cell lines, and is effective to inhibit EZH2 expression. Moreover, high levels of miR-138 are associated with long overall and progression-free survival of GBM patients from The Cancer Genome Atlas dataset (TCGA) data portal. Ectopic expression of miRNA-138 effectively inhibits GBM cell proliferation in vitro and tumorigenicity in vivo through inducing cell cycles G1/S arrest. Mechanism investigation reveals that miRNA-138 acquires tumor inhibition through directly targeting EZH2, CDK6, E2F2 and E2F3. Moreover, an EZH2-mediated signal loop, EZH2-CDK4/6-pRb-E2F1, is probably involved in GBM tumorigenicity, and this loop can be blocked by miRNA-138. Additionally, miRNA-138 negatively correlates to mRNA levels of EZH2 and CDK6 among GBM clinical samples from both TCGA and our small amount datasets. In conclusion, our data demonstrate a tumor suppressive role of miRNA-138 in GBM tumorigenicity, suggesting a potential application in GBM therapy.