Zujian Chen

MicroRNA-138 suppresses epithelial–mesenchymal transition in squamous cell carcinoma cell lines

Down-regulation of miR-138 (microRNA-138) has been frequently observed in various cancers, including HNSCC (head and neck squamous cell carcinoma). Our previous studies suggest that down-regulation of miR-138 is associated with mesenchymal-like cell morphology and enhanced cell migration and invasion. In the present study, we demonstrated that these miR-138-induced changes were accompanied by marked reduction in E-cad (E-cadherin) expression and enhanced Vim (vimentin) expression, characteristics of EMT (epithelial-mesenchymal transition). On the basis of a combined experimental and bioinformatics analysis, we identified a number of miR-138 target genes that are associated with EMT, including VIM, ZEB2 (zinc finger E-box-binding homeobox 2) and EZH2 (enhancer of zeste homologue 2). Direct targeting of miR-138 to specific sequences located in the mRNAs of the VIM, ZEB2 and EZH2 genes was confirmed using luciferase reporter gene assays. Our functional analyses (knock-in and knock-down) demonstrated that miR-138 regulates the EMT via three distinct pathways: (i) direct targeting of VIM mRNA and controlling the expression of VIM at a post-transcriptional level, (ii) targeting the transcriptional repressors (ZEB2) which in turn regulating the transcription activity of the E-cad gene, and (iii) targeting the epigenetic regulator EZH2 which in turn modulates its gene silencing effects on the downstream genes including E-cad. These results, together with our previously observed miR-138 effects on cell migration and invasion through targeting RhoC (Rho-related GTP-binding protein C) and ROCK2 (Rho-associated, coiled-coil-containing protein kinase 2) concurrently, suggest that miR-138 is a multi-functional molecular regulator and plays major roles in EMT and in HNSCC progression.

Down-regulation of the microRNA-99 family members in head and neck squamous cell carcinoma

OBJECTIVES MicroRNA deregulation is a critical event in head and neck squamous cell carcinoma (HNSCC). Several microRNA profiling studies aimed at deciphering the microRNA signatures of HNSCC have been reported, but there tends to be poor agreement among studies. The objective of this study was to survey the published microRNA profiling studies on HNSCC, and to assess the commonly deregulated microRNAs in an independent sample set. MATERIALS AND METHODS Meta-analysis of 13 published microRNA profiling studies was performed to define microRNA signatures in HNSCC. Selected microRNAs (including members of miR-99 family) were evaluated in an independent set of HNSCC cases. The potential contributions of miR-99 family to the tumorigenesis of HNSCC were assessed by in vitro assays. RESULTS We identified 67 commonly deregulated microRNAs. The up-regulation of miR-21, miR-155, miR-130b, miR-223 and miR-31, and the down-regulation of miR-100, miR-99a and miR-375 were further validated in an independent set of HNSCC cases with quantitative RT-PCR. Among these validated microRNAs, miR-100 and miR-99a belong to the miR-99 family. Our in vitro study demonstrated that restoration of miR-100 to the HNSCC cell lines suppressed cell proliferation and migration, and enhanced apoptosis. Furthermore, ectopic transfection of miR-99 family members down-regulated the expression of insulin-like growth factor 1 receptor (IGF1R) and mechanistic target of rapamycin (mTOR) genes. CONCLUSION In summary, we described a panel of frequently deregulated microRNAs in HNSCC, including members of miR-99 family. The deregulation of miR-99 family contributes to the tumorigenesis of HNSCC, in part by targeting IGF1R and mTOR signaling pathways.

Identification and experimental validation of G protein alpha inhibiting activity polypeptide 2 (GNAI2) as a microRNA-138 target in tongue squamous cell carcinoma

MicroRNA deregulation is a critical event in tumor initiation and progression. The down-regulation of microRNA-138 has been frequently observed in various cancers, including tongue squamous cell carcinoma (TSCC). Our previous studies suggest that deregulation of miR-138 is associated with the enhanced proliferation and invasion in TSCC cells. Here, we seek to identify the targets of miR-138 in TSCC, and explore their functional relevance in tumorigenesis. Our genome-wide expression profiling experiments identified a panel of 194 unique transcripts that were significantly down-regulated in TSCC cells transfected with miR-138. A comprehensive screening using six different sequence-based microRNA target prediction algorithms revealed that 51 out of these 194 down-regulated transcripts are potential direct targets for miR-138. These targets include: chloride channel, nucleotide-sensitive, 1A (CLNS1A), G protein alpha inhibiting activity polypeptide 2 (GNAI2), solute carrier family 20, member 1 (SLC20A1), eukaryotic translation initiation factor 4E binding protein 1 (EIF4EBP1), and Rho-related GTP-binding protein C (RhoC). GNAI2 is a known proto-oncogene that is involved in the initiation and progression of several different types of tumors. Direct targeting of miR-138 to two candidate binding sequences located in the 3′-untranslated region of GNAI2 mRNA was confirmed using luciferase reporter gene assays. Knockdown of miR-138 in TSCC cells enhanced the expression of GNAI2 at both mRNA and protein levels. In contrast, ectopic transfection of miR-138 reduced the expression of GNAI2, which, in consequence, led to reduced proliferation, cell cycle arrest and apoptosis. In summary, we identified a number of high-confident miR-138 target genes, including proto-oncogene GNAI2, which may play an important role in TSCC initiation and progression.

Polycomb group protein EZH2‐mediated E‐cadherin repression promotes metastasis of oral tongue squamous cell carcinoma

Enhancer of Zeste homolog 2 (EZH2) is a critical component of the polycomb‐repressive complex 2 (PRC2) that regulates many essential biological processes, including embryogenesis and many developmental events. The oncogenic role of EZH2 has recently been implicated in several cancer types. In this study, we first confirmed that the over‐expression of EZH2 is a frequent event in oral tongue squamous cell carcinoma (OTSCC). We further demonstrated that EZH2 over‐expression is correlated with advanced stages of the disease and is associated with lymph node metastasis. Statistical analysis revealed that EZH2 over‐expression was correlated with reduced overall survival. Furthermore, over‐expression of EZH2 was correlated with reduced expression of tumor suppressor gene E‐cadherin. These observations were confirmed in vitro, in which knockdown of EZH2‐induced E‐cadherin expression and reduced cell migration and invasion. In contrast, ectopic transfection of EZH2 led to reduced E‐cadherin expression and enhanced cell migration and invasion. Furthermore, EZH2 may act on cell migration in part by suppressing the E‐cadherin expression. Taken together, these data suggest that EZH2 plays major roles in the progression of OTSCC, and may serve as a biomarker or therapeutic target for patients at risk of metastasis.

Molecular Characterization of the MicroRNA-138-Fos-like Antigen 1 (FOSL1) Regulatory Module in Squamous Cell Carcinoma

Background: MicroRNA-138 deregulation is a common event in cancer. Results: Our study describes a microRNA regulatory module consisting of tumor suppressor miR-138 and proto-oncogene FOSL1. Conclusion: The deregulation of miR-138-FOSL1 regulatory module may play an important role in cancer initiation and progression. Significance: Our results suggest that microRNAs target both canonical and non-canonical targeting sites located in all areas of mRNA molecules. MicroRNA-138 is one of the most frequently down-regulated microRNAs in cancer. We recently identified 51 candidate targets of microRNA-138 (Jiang, L., Dai, Y., Liu, X., Wang, C., Wang, A., Chen, Z., Heidbreder, C. E., Kolokythas, A., and Zhou, X. (2011) Hum. Genet. 129, 189–197). Among these candidates, Fos-like antigen 1 (FOSL1) is a member of Fos gene family and is a known proto-oncogene. In this study, we first confirmed the microRNA-138-mediated down-regulation of FOSL1 in squamous cell carcinoma cell lines. We then demonstrated the effect of this microRNA-138-FOSL1 regulatory module on downstream genes (homolog of Snail 2 (Snai2) expression and the Snai2-mediated repression of E-cadherin expression), as well as its contributions to tumorigenesis. The microRNA-138-directed recruitment of FOSL1 mRNA to the RNAi-induced silencing complex was confirmed by a ribonucleoprotein-immunoprecipitation assay. Three canonical and three high affinity non-canonical microRNA-138 (miR-138) targeting sites were identified on the FOSL1 mRNA: one in the 5′-UTR, three overlapping sites in the coding sequences, and two overlapping sites in the 3′-UTR. The direct targeting of miR-138 to these sites was confirmed using luciferase reporter gene assays. In summary, we describe an important microRNA regulatory module, which may play an important role in cancer initiation and progression. Our results also provide evidence that microRNAs target both canonical and non-canonical targeting sites located in all areas of the mRNA molecule (e.g. 5′-UTR, coding sequences, and 3′-UTR).

microRNA-21 and microRNA-375 from oral cytology as biomarkers for oral tongue cancer detection

OBJECTIVE We previously performed a meta-analysis of microRNA profiling studies on head and neck/oral cancer (HNOC), and identified 11 consistently dysregulated microRNAs in HNOC. Here, we evaluate the diagnostic values of these microRNAs in oral tongue squamous cell carcinoma (OTSCC) using oral cytology samples. MATERIALS AND METHODS The levels of 11 microRNAs were assessed in 39 oral cytology samples (19 OTSCC and 20 normal subjects), and 10 paired OTSCC and adjacent normal tissues. The predictive power of these microRNAs was analyzed by receiver operating characteristic curve (ROC) and random forest (RF) model. A classification and regression trees (CART) model was generated using miR-21 and miR-375, and further validated using both independent oral cytology validation sample set (14 OTSCC and 11 normal subjects) and tissue validation sample set (12 paired OTSCC and adjacent normal tissues). RESULTS Differential expression of miR-21, miR-100, miR-125b and miR-375 was validated in oral cytology training sample set. Based on the RF model, the combination of miR-21 and miR-375 was selected which provide best prediction of OTSCC. A CART model was constructed using miR-21 and miR-375, and was tested in both oral cytology and tissue validation sample sets. A sensitivity of 100% and specificity of 64% was achieved in distinguishing OTSCC from normal in the oral cytology validation set, and a sensitivity of 83% and specificity of 83% was achieved in the tissue validation set. CONCLUSION The utility of microRNA from oral cytology samples as biomarkers for OTSCC detection is successfully demonstrated in this study.

miR-486-3p, miR-139-5p, and miR-21 as Biomarkers for the Detection of Oral Tongue Squamous Cell Carcinoma

Oral tongue squamous cell carcinoma (TSCC) is a complex disease with extensive genetic and epigenetic defects, including microRNA deregulation. The aims of the present study were to test the feasibility of performing the microRNA profiling analysis on archived TSCC specimens and to assess the potential diagnostic utility of the identified microRNA biomarkers for the detection of TSCC. TaqMan array-based microRNA profiling analysis was performed on 10 archived TSCC samples and their matching normal tissues. A panel of 12 differentially expressed microRNAs was identified. Eight of these differentially expressed microRNAs were validated in an independent sample set. A random forest (RF) classification model was built with miR-486-3p, miR-139-5p, and miR-21, and it was able to detect TSCC with a sensitivity of 100% and a specificity of 86.7% (overall error rate = 6.7%). As such, this study demonstrated the utility of the archived clinical specimens for microRNA biomarker discovery. The feasibility of using microRNA biomarkers (miR-486-3p, miR-139-5p, and miR-21) for the detection of TSCC was confirmed.

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

BackgroundOral 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.MethodsA 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.ResultsOur 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.ConclusionsWe 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.

High glucose enhances the metastatic potential of tongue squamous cell carcinoma via the PKM2 pathway

Previous evidence has indicated an increased cancer risk in individuals with diabetes mellitus (DM). The aim of this study was to investigate the relationship between DM (high glucose) and tongue squamous cell carcinoma (TSCC) and how high glucose mediated the metastatic potential of TSCC. The relationship between DM and TSCC was assessed in a retrospective study. The role and its mechanism of high glucose on the proliferation, metastatic potential of TSCC were investigated in vitro and in vivo. The prevalence rate of DM in patients with TSCC was 12.84%, which was significantly higher than that (9.7%) in the general population in China. Although no significant difference was observed in the overall survival (OS) rate, TSCC patients with DM have a 1.38-fold increase in relative risk affecting 5-year OS compared to patients without DM. High glucose enhanced the TSCC cell proliferation, migration, invasion and upregulated PKM2 (pyruvate kinase M2) expression. Whereas, these effect was abolished after knockdown of PKM2 in TSCC cells. High glucose promoted tumour growth and lung metastasis of TSCC in a DM animal model. Our results confirm DM as a risk factor for the development of TSCC. High glucose enhances the metastatic potential of TSCC through stimulation of the PKM2 pathway.

Abstract 704: Hyperglycemia stimulates glycolysis and enhances migratory/invasive potential in tongue squamous cell carcinoma

Objective: The aim of this study was to investigate the role of glycolysis (HK2/PKM2) in the development of tongue squamous cell carcinoma (TSCC) and elucidate how hyperglycaemia stimulate HK2 and PKM2 and enhance migration/invasion potential in TSCC. Methods: A total of 501 patients which diagnosed as TSCC between 1998 and 2004 were enrolled in the retrospective study. The expression of HK2/PKM2 was examined by IHC and the relationship between TSCC and diabetes mellitus (DM) was investigated. We then investigated the role of HK2/PKM2 in the migration and invasion of TSCC and relevant pathways (the SOD2-H2O2 pathway and miR-138 pathway). Finally, we investigated whether hyperglycaemia enhance migratory/invasive potential of TSCC through stimulating glycolysis. Results: The prevalent rate of TSCC patients with diabetes was 13.97%, which was significantly higher than the incidence rate of DM (11.6%) in China. Cox analysis revealed that the HR for patients with DM vs without DM was 1.32. IHC results confirmed that the up-regulation of PKM2/HK2 expression was correlated with tumor stage, clinical stages, diabetes, lymph node metastasis and associated with reduced overall survival. PKM2/HK2/AKT1 overexpression increased cell migration and invasion, SOD2 activities and intracellular H2O2. The siRNA-based PKM2/HK2 knockdown inhibited cell migration and invasion, reduced activities of SOD2 and intracellular H2O2, and also inhibited tumor growth and lung metastasis in vivo. Luciferase assays revealed that PKM2/AKT1 was directly targeted by miR-138 and miR-138 can reduce the expression of the PKM2/AKT1 gene. High glucose enhanced the migration/invasion ability, miR-138/PKM2/HK2 expression and increased SOD2 activities and intracellular H2O2. Conclusions: Our results confirm that DM may be a risk factor in the development of TSCC. PKM2/HK2 plays an important role in the progression of TSCC, and may serve as a biomarker or therapeutic target for patients with TSCC. High glucose stimulates glycolysis (PKM2/HK2) and enhances migration/invasion potential in TSCC. Citation Format: Anxun Wang, Wei Wang, Luodan Zhao, Qianting He, Jingjing Sun, Zhonghua Liu, Zujian Chen, Xiaofeng Zhou. Hyperglycemia stimulates glycolysis and enhances migratory/invasive potential in tongue squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 704.