MicroRNA-802 plays a tumour suppressive role in tongue squamous cell carcinoma through directly targeting MAP2K4

SNHG1/miR-194-5p/MTFR1 Axis Promotes TGFβ1-Induced EMT, Migration and Invasion of Tongue Squamous Cell Carcinoma Cells

Tongue squamous cell carcinoma (TSCC) is a common malignancy with aggressive biological behaviors. Mitochondrial fission regulator 1 (MTFR1), is aberrantly expressed in head and neck squamous cell carcinoma (HNSC), but its role in TSCC remains unclear. We aimed to explore the role of MTFR1 in TSCC. The expression of long non-coding RNA small nucleolar RNA host gene 1 (SNHG1), microRNA-194-5p and MTFR1 in TSCC cells was measured by RT-qPCR. Luciferase reporter assay and RNA pull down assay were applied to confirm the binding capacity between miR-194-5p and SNHG1 (or MTFR1). TSCC cell invasion and migration were accessed by Transwell assays. The protein levels of MTFR1 and epithelial-mesenchymal transition (EMT) markers were examined by western blot. MTFR1 had high expression level in TSCC. MTFR1 knockdown inhibited transforming growth factor β1 (TGFβ1)-induced EMT, migration and invasion of TSCC cells in vitro. MiR-194-5p targeted MTFR1 and negatively regulated its expression. In addition, SNHG1 upregulated the expression of MTFR1 by binding with miR-194-5p. Importantly, SNHG1 promoted EMT, invasion and migration of TSCC cells by upregulating MTFR1. SNHG1/miR-194-5p/MTFR1 axis promotes TGFβ1-induced EMT, migration and invasion of cells in TSCC, which could be potential targets for treating TSCC patients.

Experiments from unfinished Registered Reports in the Reproducibility Project: Cancer Biology

As part of the Reproducibility Project: Cancer Biology, we published Registered Reports that described how we intended to replicate selected experiments from 29 high-impact preclinical cancer biology papers published between 2010 and 2012. Replication experiments were completed and Replication Studies reporting the results were submitted for 18 papers, of which 17 were accepted and published by eLife with the rejected paper posted as a preprint. Here, we report the status and outcomes obtained for the remaining 11 papers. Four papers initiated experimental work but were stopped without any experimental outcomes. Two papers resulted in incomplete outcomes due to unanticipated challenges when conducting the experiments. For the remaining five papers only some of the experiments were completed with the other experiments incomplete due to mundane technical or unanticipated methodological challenges. The experiments from these papers, along with the other experiments attempted as part of the Reproducibility Project: Cancer Biology, provides evidence about the challenges of repeating preclinical cancer biology experiments and the replicability of the completed experiments.

Dysfunction of miR-802 in tumors

Recent studies have shown that miR-802 is abnormally expressed in many tumors. miR-802 is expressed at low levels in tissues and cells of gastric cancer, colorectal cancer, breast cancer, cervical cancer, epithelial ovarian cancer, tongue squamous cell carcinoma, oral squamous cell carcinoma, esophageal squamous cell carcinoma, laryngeal squamous cell carcinoma, and melanoma. In contrast, miR-802 is overexpressed in hepatocellular carcinoma, bladder urothelial cancer, osteosarcoma, and cholesteatoma tissue cells. It should be noted that the results of studies on the expression of miR-802 in pancreatic cancer, prostate cancer, and lung cancer are inconsistent. Current studies have found that miR-802 can target and regulate genes in different tumors, and affect the regulation of the Wnt signaling pathway, EMT signaling pathway, PI3K/AKT signaling pathway, ERK signaling pathway, and Hedgehog signaling pathway. At the same time, miR-802 is regulated by the endogenous competition of four ceRNAs, including circDONSON, IGFL2-AS1, MIR155HG, and MIR4435-2HG. This article reviews the abnormal expression of miR-802 in a variety of tumors, expounds the mechanism by which miR-802 affects tumor progression by regulating different target genes, and elaborates the network of miR-802-related ceRNAs. We also summarized the limitations of miR-802 research and looked forward to the potential application of miR-802 in the diagnosis and prognosis of tumors.

LUCAT1 as an oncogene in tongue squamous cell carcinoma by targeting miR-375 expression

Emerging studies suggested that lncRNAs play a crucial molecular role in cancer development and progression. LncRNA LUCAT1 has been proved as oncogenic molecular in lung cancer, glioma, osteosarcoma, renal carcinoma and oesophageal squamous cell carcinoma. However, its roles and function mechanisms in tongue squamous cell carcinoma (TSCC) are still unknown. We showed that the expression of LUCAT1 was up‐regulated in the TSCC cells and tissues and the higher LUCAT1 expression was associated with the poor overall survival (OS). Knockdown expression of LUCAT1 suppressed TSCC cell proliferation, cycle and migration. In addition, we demonstrated that miR‐375 overexpression inhibited the luciferase activity of LUCAT1 wild‐type and knockdown LUCAT1 promoted the miR‐375 expression in TSCC cell. Furthermore, we indicated that miR‐375 expression was down‐regulated in the TSCC cell lines and tissues and the lower expression of miR‐375 was associated with poor OS. The expression of miR‐375 was inversely correlated with LUCAT1 expression in the TSCC tissues. Knockdown LUCAT1 promoted TSCC cell proliferation, cell cycle and migration partly through regulating miR‐375 expression. In summary, this study suggested the tumorigenic effect of lncRNA LUCAT1 in TSCC cells by targeting miR‐375 expression.

lncRNA RPSAP52 induced the development of tongue squamous cell carcinomas via miR-423-5p/MYBL2

Growing lncRNAs have been noted to involve in the initiation and development of several tumours including tongue squamous cell carcinomas (TSCCs). However, the biological role and mechanism of lncRNA RPSAP52 were not well‐explained. We indicated that RPSAP52 was higher in TSCC samples compared with that in control samples. The higher expression of RPSAP52 was positively correlated with higher T stage and TNM stage. Ectopic expression of RPSAP52 induced TSCC cell growth and cycle and induced cytokine secretion including IFN‐γ, IL‐1β and IL‐6, IL‐8, IL‐10 and TGF‐β. We found that the overexpression of RPSAP52 suppressed miR‐423‐5p expression in SCC‐4 cell. miR‐423‐5p was lower in TSCC samples compared with that in control samples, and miR‐423‐5p level was negatively correlated with higher T stage and TNM stage. Pearson's correlation indicated that miR‐423‐5p was negatively associated with that of RPSAP52 in TSCC tissues. Furthermore, MYBL2 was one direct gene of miR‐423‐5p and elevated expression of miR‐423‐5p suppressed MYBL2 expression and ectopic expression of RPSAP52 increased MYBL2 expression in SCC‐4 cell. Finally, we illustrated that RPSAP52 overexpression promoted TSCC cell growth and cycle and induced cytokine secretion including IFN‐γ, IL‐1β and IL‐6, IL‐8, IL‐10 and TGF‐β via modulating MYBL2. These data provided new insight into RPSAP52, which may be one potential treatment target for TSCC.

Identification of MYLIP gene and miRNA-802 involved in the growth and metastasis of cervical cancer cells

BACKGROUND

The dysregulation of microRNA-802 (miR-802) has crucial roles in cancer progression. Nevertheless, the bio-function of miR-802 in cervical cancer remains unclear.

OBJECTIVE

Hence, we illuminated the potential roles of miR-802 in cervical cancer cell growth, migration, and invasion.

METHODS

The levels of miR-802 and myosin regulatory light chain interacting protein (MYLIP) were measured using qRT-PCR assay. The potential effects of miRNA-802 on cervical cancer cell proliferation and metastatic phenotypes were determined using CCK-8, colony formation, wound healing and Transwell invasion assays. MYLIP was validated as a downstream target gene of miRNA-802 using bioinformatics analysis tool and luciferase report gene assay. The impact of miR-802 on the growth of cervical cancer cell in vivo was analyzed using xenograft model. The expression of MYLIP was measured by western blotting and immunohistochemistry (IHC).

RESULTS

MiRNA-802 was distinctly down-regulated in cervical cancer cells as well as clinical cervical cancer samples. Upregulation of miRNA-802 significantly inhibited the growth and aggressiveness of cervical cancer cell. Additional, MYLIP was a functional target of miR-802. MYLIP was ovrerexpressed in cervical cancer and MYLIP level was negatively associated with the level of miR-802. Overexpression of MYLIP eliminated the inhibitory effects of miR-802 on growth and metastatic-related traits of cervical cancer cell. In vivo, miR-802 also markedly reduced the tumor growth of cervical cancer cell and decreased the expression of MYLIP.

CONCLUSIONS

MiR-802 inhibits the growth and metastatic-related phenotypes of cervical cancer cell through targeting MYLIP.

MicroRNA-802 Suppresses Tumorigenesis of Colorectal Cancer via Regulating UBN2

BACKGROUND

The initiation and progression of colorectal cancer (CRC) are a multistep complex process regulated by multiple factors. Previous evidence indicated that microRNA-802 (miR-802) participated in tumorigenesis of numerous solid cancers; however, the potential roles and underlying mechanisms of miR‑802 in CRC still need further exploration.

METHODS

Quantitative real-time PCR (qRT-PCR) was employed to evaluate miR-802 levels in human CRC tissues and cell lines. In vitro proliferation, apoptosis, migration and invasion assays, and in vivo subcutaneous mouse xenograft model were utilized to examine the effects of miR-802 on the malignant behaviors of CRC cells. Then, bioinformatics prediction, dual-luciferase reporter, qRT-PCR, and Western blot was conducted to confirm the down-stream target of miR-802.

RESULTS

MiR-802 was frequently down-regulated in CRC tissues and cells. Further analyses showed that the low expression of miR-802 in CRC tissues was significantly correlated with tumor progression and poor patients' prognosis. Overexpression of miR-802 profoundly inhibited proliferation, migration and invasion but promoted apoptosis of CRC cells, by contrast, miR-802 silencing exhibited opposite effects in vitro. Further animal experiment demonstrated that miR-802 could suppress tumor growth via inhibiting the proliferation and promoting the apoptosis of CRC cells in vivo. Mechanistically, miR-802 functioned as a tumor suppressor through inhibiting the expression of Ubinuclein-2 (UBN2) on post-transcriptional level. Moreover, upregulation of UBN2 expression could reverse the biological effects of CRC cells induced by miR-802 overexpression.

CONCLUSION

Our study demonstrates that miR-802 inhibits the proliferation, migration and invasion while promotes the apoptosis of CRC cells via directly suppressing UBN2 expression. These findings provide a promising biomarker and potential treatment target for CRC.

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.

TRG-AS1 is a potent driver of oncogenicity of tongue squamous cell carcinoma through microRNA-543/Yes-associated protein 1 axis regulation

The long noncoding RNA T cell receptor gamma locus antisense RNA 1 (TRG-AS1) plays an important role in glioblastoma progression. The objective of this study was to determine the expression status of TRG-AS1 in tongue squamous cell carcinoma (TSCC). The regulatory effects of TRG-AS1 depletion on the malignant processes of TSCC cells were illustrated both in vitro and in vivo. Additionally, the precise molecular mechanisms through which TRG-AS promotes TSCC oncogenicity were investigated. TRG-AS1 expression in TSCC tissues and cell lines was detected using reverse transcription-quantitative PCR. Functional experiments including Cell Counting Kit-8 assay, flow cytometric apoptotic assay, migration and invasion assays, and xenograft tumor model analysis were conducted to severally determine the effects of TRG-AS1 on TSCC cell proliferation, apoptosis, migration, and invasion in vitro and tumor growth in vivo. Herein, TRG-AS1 was highly expressed in TSCC and closely associated with advanced TNM stage, high lymph node metastasis, and poor overall survival. Functionally, TRG-AS1 depletion suppressed TSCC cell proliferation, migration, and invasion in vitro; promoted cell apoptosis; and attenuated tumor growth in vivo. Mechanistically, TRG-AS1 served as a molecular sponge for microRNA-543 (miR-543), thereby contributing to the increased expression of Yes-associated protein 1 (YAP1) - a miR-543 target. Rescue experiments confirmed that miR-543 inhibition or YAP1 overexpression abrogated the anticancer effects of TRG-AS1 silencing in TSCC cells. In conclusion, TRG-AS1 aggravates TSCC malignancy by regulating the miR-543/YAP1 axis. Identification of the TRG-AS1/miR-543/YAP1 regulatory pathway may provide novel insights into TSCC diagnosis, prognosis, and therapy.

miR‑802 inhibits the epithelial‑mesenchymal transition, migration and invasion of cervical cancer by regulating BTF3

MicroRNA (miR)-802 has been discovered to be involved in the occurrence and development of numerous types of tumor; however, studies into the role of miR‑802 in cervical cancer are limited. Therefore, the present study aimed to investigate the regulatory effects of miR‑802 in cervical cancer cells. miR‑802 expression levels in cervical cancer tissue and cells were analyzed using reverse transcription‑quantitative (RT‑q)PCR, a dual‑reporter luciferase activity assay was used to identify the direct target gene of miR‑802, and RT‑qPCR and western blotting were performed to determine the relationship between miR‑802 and basic transcription factor 3 (BTF3). Cell viability, and migration and invasion were analyzed using Cell Counting Kit‑8 and Transwell assays, respectively. Finally, the expression levels of metastasis‑associated proteins, N‑cadherin and E‑cadherin, were determined using RT‑qPCR and western blotting. Decreased expression levels of miR‑802 were found in cervical cancer tissues and cells, and the overexpression of miR‑802 inhibited cell viability, migration and invasion. Moreover, miR‑802 was discovered to directly target BTF3 to inhibit its expression. Notably, the overexpression miR‑802 markedly reversed the promotive effect of BTF3 on cell viability, in addition to the migratory and invasive abilities of the cells. Simultaneously, the overexpression of miR‑802 significantly suppressed epithelial‑mesenchymal transition, and the expression levels of matrix metallopeptidase (MMP)2 and MMP9 in cells through regulating BTF3. In conclusion, the present study revealed that miR‑802 may suppress cervical cancer progression by decreasing BTF3 expression levels, indicating that it may represent a potential therapeutic target for the treatment and prognosis of patients with cervical cancer.

Non-Coding RNAs as Potential Novel Biomarkers for Early Diagnosis of Hepatic Insulin Resistance

In the recent years, the prevalence of metabolic conditions such as type 2 Diabetes (T2D) and metabolic syndrome (MetS) raises. The impairment of liver metabolism resulting in hepatic insulin resistance is a common symptom and a critical step in the development of T2D and MetS. The liver plays a crucial role in maintaining glucose homeostasis. Hepatic insulin resistance can often be identified before other symptoms arrive; therefore, establishing methods for its early diagnosis would allow for the implementation of proper treatment in patients before the disease develops. Non-coding RNAs such as miRNAs (micro-RNA) and lncRNAs (long-non-coding RNA) are being recognized as promising novel biomarkers and therapeutic targets—especially due to their regulatory function. The dysregulation of miRNA and lncRNA activity has been reported in the livers of insulin-resistant patients. Many of those transcripts are involved in the regulation of the hepatic insulin signaling cascade. Furthermore, for several miRNAs (miR-802, miR-499-5p, and miR-122) and lncRNAs (H19 imprinted maternally expressed transcript (H19), maternally expressed gene 3 (MEG3), and metastasis associated lung adenocarcinoma transcript 1 (MALAT1)), circulating levels were altered in patients with prediabetes, T2D, and MetS. In the course of this review, the role of the aforementioned ncRNAs in hepatic insulin signaling cascade, as well as their potential application in diagnostics, is discussed. Overall, circulating ncRNAs are precise indicators of hepatic insulin resistance in the development of metabolic diseases and could be applied as early diagnostic and/or therapeutic tools in conditions associated with insulin resistance.

microRNA-124-3p inhibits tumourigenesis by targeting mitogen-activated protein kinase 4 in papillary thyroid carcinoma

The study aimed to investigate the role of miR-124-3p and its potential molecular mechanism in papillary thyroid cancer (PTC). The expression of miR-124-3p and mitogen-activated protein kinase 4 (MAP2K4) in human thyroid follicular epithelial cell line (NTHY-ORI3-1) and human papillary thyroid carcinoma cell lines (SW1736, BCPAP, TPC-1 and K1) was measured by RT-qPCR. Cell proliferation was measured by CCK-8, while cell cycle and apoptosis rate were measured by flow cytometry. Invasive ability and migrative ability were measured by transwell assay and wound healing assay, respectively. Western blot was used to detect the levels of relative proteins. In vivo, TPC-1 cells transfected with miR-124-3p mimic were subcutaneously injected into the flank of the mice to form tumour. After successful modelling, mice were divided into two groups (n = 10): Control group and miR-124-3p mimic group. The present study showed that miR-124-3p was lowly expressed, while MAP2K4 was highly expressed in PTC cell lines. Besides, miR-124-3p targeted MAP2K4 and negatively regulated MAP2K4 in TPC-1 cells. In addition, miR-124-3p inhibited the proliferation and motility, and induced apoptosis and cell cycle arrest of TPC-1 cells by inactivating MAP2K4/JNK/JunD pathway. Furthermore, miR-124-3p inhibited tumour formation by downregulating MAP2K4 level in vivo. In conclusion, the study provided a novel molecular mechanism of miR-124-3p in the progress of PTC. SIGNIFICANCE OF THE STUDY: Papillary thyroid cancer (PTC) is the most important pathological type of thyroid cancer, accounting for 80% of thyroid cancer. miR-124-3p exhibited significant inhibitory role in the transformation and development of malignant tumours. However, in PTC, the roles and its potential molecular mechanism are unclear. Here, the study investigated the roles of miR-124-3p in the progress of PTC and its potential molecular mechanism. We found that miR-124-3p inhibited the proliferation and motility, and induced apoptosis and cell cycle arrest in PTC cells. This study provided a novel molecular mechanism of miR-124-3p in the progress of PTC.

MiR-26a/miR-26b represses tongue squamous cell carcinoma progression by targeting PAK1

Background

Tongue squamous cell carcinoma (TSCC) is the most common oral malignancy. Previous studies found that microRNA (miR)-26a and miR-26b were downregulated in TSCC tissues. The current study was designed to explore the effects of miR-26a/miR-26b on TSCC progression and the potential mechanism.

Methods

Expression of miR-26a, miR-26b and p21 Activated Kinase 1 (PAK1) in TSCC tissues and cell lines was detected by reverse transcription- quantitative polymerase chain reaction (RT-qPCR). Flow cytometry analysis was performed to examine cell cycle and apoptosis. Transwell assay was conducted to evaluate the migrated and invasive abilities of SCC4 and Cal27 cells. In addition, western blot assay was employed to analyze the protein level. Glucose assay kit and lactate assay kit were utilized to analyze glycolysis. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were applied to explore the relationship between miR-26a/miR-26b and PAK1. Xenograft tumor model was constructed to explore the role of miR-26a/miR-26b in vivo.

Results

Both miR-26a and miR-26b were underexpressed, while PAK1 was highly enriched in TSCC. Overexpression of miR-26a and miR-26b inhibited TSCC cell cycle, migration invasion and glycolysis, while promoted cell apoptosis. Both miR-26a and miR-26b directly targeted and negatively regulated PAK1 expression. Introduction of PAK1 partially reversed miR-26a/miR-26b upregulation-mediated cellular behaviors in TSCC cells. Gain of miR-26a/miR-26b blocked TSCC tumor growth in vivo.

Conclusion

MiR-26a/miR-26b repressed TSCC progression via targeting PAK1 in vitro and in vivo, which enriched our understanding about TSCC development and provided new insights into the its treatment.

MiR-802 alleviates lipopolysaccharide-induced acute lung injury by targeting Peli2

Introduction

Acute respiratory distress syndrome (ARDS) is a life-threatening medical condition. It is characterized by serious lung inflammation or injury. Characterizing novel miRNAs implicated in ARDS pathogenesis may provide new therapeutic strategy for managing ARDS.

Methods

We employed LPS-induced lung injury model to profile miRNAs associated with ARDS. We isolated one miRNA candidate and characterized its role in lipopolysaccharide (LPS)-induced proinflammatory cytokine production in lung macrophages. We further evaluated its functional role in ARDS model by assessing histological change, neutrophil activation, tissue permeability and tumor necrosis factor alpha (TNFα) production. We also characterized its downstream target using luciferase assay, Western blotting, enzyme-linked immunosorbent assay and cell inflammation assay.

Results

Microarray profiling revealed miR-802 was significantly downregulated in ARDS mouse model. LPS-induced miR-802 downregulation was confirmed in lung macrophages. Overexpression of miR-802 significantly suppressed LPS-induced inflammatory cytokine production in vitro and alleviates LPS-induced acute lung injury in vivo. Peli2 was identified as a downstream target of miR-802 and found upregulated in ARDS model. Overexpressing Peli2 abolished the antagonizing effect of miR-802 on LPS-mediated inflammatory response.

Conclusion

MiR-802 carried a protective role against LPS-induced acute lung injury by downregulating Peli2. MiR-802/Peli2 axis may act as intervening targets to manage ARDS.

Ensemble structural analyses depict the regulatory mechanism of non-phosphorylated human MAP2K4

Mitogen-activated protein kinase kinase 4 (MAP2K4) plays a critical role in regulating the stress-activated protein kinase signaling cascade. A small angle X-ray scattering experiment, a powerful technique for analyzing a solution structure cleared from the structural artifacts due to crystal packing, provided the ensemble structures of human non-phosphorylated MAP2K4 in three states involving the apo form, the binary complex with an ATP analogue, and the ternary complex with the ATP analogue and substrate peptide. These ensemble structures provided more detailed mechanisms for regulating MAP2K4 in addition to those delineated only by the crystal structures in three states.

MicroRNA-802 induces hepatitis B virus replication and replication through regulating SMARCE1 expression in hepatocellular carcinoma

Growing evidences have indicated that microRNAs (miRNAs) can regulate hepatitis B virus (HBV) expression and replication, playing crucial roles in the development of HBV infection. Until now, the functional role and mechanism of miR-802 in HBV replication and expression remain unknown. We indicated that miR-802 expression was upregulated in the HBV-associated hepatocellular carcinoma (HCC) tissues compared with the adjacent noncancerous samples. In addition, we showed that the SMARCE1 expression level was downregulated in the HBV-associated HCC tissues compared with the adjacent noncancerous samples. miR-802 expression was negatively related with MARCE1 expression in HBV-associated HCC tissues. Moreover, miR-802 expression was upregulated, and SMARCE1 expression was downregulated in the HBV-infected HepG2.2.15 cells. Ectopic expression of miR-802 significantly enhanced HBV DNA replication, while knockdown of miR-802 significantly decreased HBV DNA replication. We showed that overexpression of miR-802 promoted HbsAg and HbeAg expression, while inhibition of miR-802 decreased HbsAg and HbeAg expression. Furthermore, we indicated that ectopic expression of SMARCE1 suppressed HBV DNA replication and decreased the expression level of HbsAg and HbeAg. Finally, we showed that overexpression of miR-802 promoted HBV DNA replication through regulating SMARCE1 expression. These results suggested the important roles of miR-802 on HBV expression and replication, which may shed new light on the development of treatment for HBV.

microRNA-493 inhibits tongue squamous cell carcinoma oncogenicity via directly targeting HMGA2

Backgrounds

microRNA-493-3p (miR-493) has been reported to be critically downregulated in multiple types of human cancer. However, the expression level, biological roles and underlying mechanism of miR‑493 in tongue squamous cell carcinoma (TSCC) remain to be elucidated.

Methods

RT-qPCR was utilized for the determination of miR-493 expression in TSCC tissues and cell lines. The influence of miR-493 overexpression on TSCC cell proliferation, apoptosis, migration, invasion in vitro and tumor growth in vivo were explored via MTT assay, flow cytometry analysis, cell migration and invasion assays, and xenograft tumors in nude mice, respectively. Bioinformatics analysis, luciferase reporter assays, RT-qPCR and Western blotting were performed to clarify the potential mechanisms involved in the action of miR-493 in TSCC cells.

Results

miR-493 was significantly downregulated in TSCC tissues and cell lines. Decreased miR-493 expression was notably correlated with tumor differentiation, depth of invasion and TNM stage. Additionally, patients with TSCC having low miR-493 expression showed lower overall survival rate. Functionally, miR-493 upregulation inhibited TSCC cell proliferation, migration, invasion in vitro; induced cell apoptosis; and decreased the tumor growth in vivo. Bioinformatics analysis followed by luciferase reporter assays also demonstrated that miR-493 directly bound to the 3'-untranslated region of high-mobility group AT-hook 2 (HMGA2) in TSCC cells, and therefore reduced HMGA2 expression at the mRNA and protein level. Furthermore, HMGA2 was overexpressed in TSCC tissues and inversely correlated with miR-493. Moreover, silenced HMGA2 expression simulated the tumor-suppressing roles of miR-493 overexpression on TSCC cells. HMGA2 overexpression eliminated the inhibitory roles of miR-493 overexpression on TSCC cells.

Conclusion

These observations demonstrated that miR-493 is a tumor suppressor inhibited the oncogenicity of TSCC cells by directly targeting HMGA2. These results provide sufficient evidence for the miR-493/HMGA2 axis as a novel therapeutic target for the treatment of patients with TSCC in the future.

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.

Association of SP1 rs1353058818 and STAT3 rs1053004 gene polymorphisms with human tongue squamous cell carcinoma

Objective: To study the association between SP1 rs1353058818 and STAT3 rs1053004 gene polymorphisms and risk of human tongue squamous cell carcinoma (TSCC).Methods: Sanger sequencing was used to determine the genotypes of SP1 rs1353058818 and STAT3 rs1053004 loci in 240 TSCC patients and 240 controls. Levels of hsa-miR-149-5p and hsa-miR-21-5p and expression levels of SP1 and STAT3 proteins in tumor tissues and adjacent normal tissues of TSCC patients were ascertained.Results: Carrying the SP1 rs1353058818 locus deletion allele was a high risk factor for TSCC (OR = 2.997, 95% CI: 1.389-6.466, P = 0.003). The STAT3 rs1053004 locus A allele was a protective factor for TSCC (OR = 0.604, 95% CI: 0.460-0.793, P < 0.001). There was a negative correlation between SP1 mRNA and hsa-miR-149-5p in tumor and adjacent normal tissues (r = -0.81, -0.77). The expression of SP1 protein in tumor tissues of the SP1 rs1353058818 locus DD genotype was significantly higher than in tissues of the ID type, and in tissues of type II it was the lowest. STAT3 mRNA was positively correlated with hsa-miR-21-5p in tumor and adjacent normal tissues (r = 0.75, 0.78). The expression level of STAT3 protein in tumor tissues of patients with STAT3 rs1053004 locus GG genotype was significantly higher than in patients with type GA, and it was the lowest in patients with type AA.Conclusion: Polymorphisms in the SP1 rs1353058818 and STAT3 rs1053004 loci are associated with the risk of human TSCC.

High Blood miR-802 Is Associated With Poor Prognosis in HCC Patients by Regulating DNA Damage Response 1 (REDD1)-Mediated Function of T Cells

miR-802 has been reported to be dysregulated in multiple tumors and contribute to tumor progression. However, its role in HCC was still largely unknown. The aim of this study is to investigate the function and mechanism of miR-802 in HCC progression. The results showed that miR-802 was upregulated in the peripheral blood and tumor tissue of HCC patients, and high levels of blood miR-802 predicted poor prognosis. miR-802 had no effect on the proliferation and migration of HCC cell lines. Interestingly, the levels of CD8/CD28 and regulated in development and DNA damage response 1 (REDD1) were declined along with the upregulation of miR-802 in vivo. Hence, it is speculated that miR-802 participated in the regulation of T-cell function in HCC patients. Furthermore, we demonstrated that mir-802 directly targets REDD1 and inhibited its expression. miR-802 increased the expression of programmed cell death protein 1 (PD-1) and decreased the expression of interferon-γ (IFN-γ) and CD8⁺CD28⁺ T-cell number. In conclusion, miR-802 was involved in T-cell exhaustion through posttranscriptionally suppressing REDD1, which might offer the suppressive effect of miR-802 on HCC progression.

miR‑802 inhibits the aggressive behaviors of non‑small cell lung cancer cells by directly targeting FGFR1

Emerging reports have revealed that several microRNAs (miRNAs) are abnormally expressed in non‑small cell lung cancer (NSCLC). miRNAs have been identified as oncogenes or tumor suppressors, and regulate various biological processes including oncogenesis and development. miR‑802 is dysregulated in multiple types of human cancer, and exerts tumor‑suppressive or promoting roles. However, the expression levels and functional roles of miR‑802 in NSCLC remain largely unknown. In the present study, miR‑802 expression was demonstrated to be decreased in NSCLC tissues and cell lines. A low miR‑802 expression was significantly correlated with the tumor stage, lymph node metastasis and brain metastasis in NSCLC patients. Restoring miR‑802 expression inhibited NSCLC cell proliferation and colony formation, induced cell apoptosis, decreased cell migration and invasion in vitro, and hindered in vivo tumor growth. Mechanistically, fibroblast growth factor receptor 1 (FGFR1) was confirmed as the target gene of miR‑802 in NSCLC cells. In addition, FGFR1 silencing mimicked the tumor‑suppressing roles of miR‑802 upregulation in NSCLC cells. Furthermore, rescue experiments revealed that FGFR1 reintroduction rescued the miR‑802‑induced inhibition of the malignant phenotypes in NSCLC cells. Notably, miR‑802 was able to deactivate the phosphoinositide 3‑kinase (PI3K)/AKT serine/threonine kinase (Akt)/mammalian target of rapamycin (mTOR) pathway in NSCLC cells in vitro and in vivo. Overall, these results demonstrated that miR‑802 could downregulate FGFR1 expression, thereby deactivating the PI3K/Akt/mTOR pathway and inhibiting the malignant development of NSCLC. Thus, miR‑802 may be a therapeutic candidate for patients with NSCLC.

MicroRNA‑758 inhibits tumorous behavior in tongue squamous cell carcinoma by directly targeting metadherin

Numerous microRNAs (miRNAs) are dysregulated in tongue squamous cell carcinoma (TSCC), and their dysregulation has been demonstrated to have a strong correlation with TSCC progression via regulation of their targets. Therefore, miRNAs have potential use in the diagnosis and treatment of patients with TSCC. In the present study, miRNA‑758 (miR‑758) expression in TSCC tissues and cell lines was detected through reverse transcription‑quantitative polymerase chain reaction, and the effects of miR‑758 on TSCC cell proliferation and invasion were investigated by using Cell Counting kit‑8 and Transwell invasion assays. A luciferase reporter assay was performed to determine the target interaction between miR‑758 and metadherin (MTDH) in TSCC cells. The results revealed that miR‑758 was downregulated in TSCC tissues and cell lines. miR‑758 overexpression restricted the proliferation and invasion of TSCC cells. Additionally, MTDH was verified as a direct target gene of miR‑758 in TSCC cells. Furthermore, MTDH was observed to be upregulated in TSCC tissues, and the upregulation of MTDH was inversely correlated with miR‑758 expression. Moreover, restored MTDH expression significantly counteracted the suppressive effects of miR‑758 overexpression on TSCC cells. These results suggested that miR‑758 may prevent TSCC progression and development by directly targeting MTDH, thereby providing evidence that miR‑758 is a novel therapeutic target for the treatment of patients with TSCC.

microRNA-802 inhibits cell proliferation and induces apoptosis in human cervical cancer by targeting serine/arginine-rich splicing factor 9

microRNAs (miRNAs) play crucial roles in cancer development and progression by targeting mRNAs for degradation and/or translational repression. microRNA-802 (miR-802) has been reported as a tumor suppressor and its deregulation is observed in various human cancers. However, the prognostic value of miR-802 and its underlying mechanisms involved in human cervical cancer are poorly investigated. The purposes of this study were to explore the role of miR-802 in cervical cancer and to clarify the regulation of serine/arginine-rich splicing factor 9 (SRSF9) by miR-802. Here, we found that miR-802 was downregulated in both cervical cancer tissues and cell lines. Transfection of a miR-802 mimic into cervical cancer cells inhibited their proliferation and colony formation, and promoted cell cycle arrest at the G0/G1 phase and cell apoptosis. In addition, we found that miR-802 could directly target the 3'-untranslated region of SRSF9 and suppress SRSF9 expression. Rescue experiments revealed that overexpression of SRSF9 partially reversed the inhibition effect of miR-802 in cervical cancer cells. Overall, these findings demonstrate that miR-802 functions as a tumor suppressor in cervical cancer by targeting SRSF9, suggesting that miR-802 might serve as a potential therapeutic target in cervical cancer.

Identification and validation of potential prognostic and predictive miRNAs of epithelial ovarian cancer

Background

Ovarian cancer is the leading cause of death by gynecologic cancers in the Western world. The aim of the study was to identify microRNAs (miRNAs) associated with prognosis and/or resistance to chemotherapy among patients with epithelial ovarian cancer.

Methods

Using information from the Pelvic Mass Study we identified a cohort of women with epithelial ovarian cancer. Tumor tissues were then collected and analyzed by global miRNA microarrays. MiRNA profiling was then linked to survival and time to progression using Cox proportional-hazards regression models. Logistic regression models were used for the analysis of resistance to chemotherapy. Our results were validated using external datasets retrieved from the NCBI Gene Expression Omnibus database.

Results

A total of 197 patients with epithelial ovarian cancer were included for miRNA microarray analysis. In multivariate analyses we identified a number of miRNAs significantly correlated with overall survival (miR-1183 (HR: 1.42, 95% CI:1.17–1.74, p = 0.0005), miR-126-3p (HR: 1.38, 95% CI:1.11–1.71, p = 0.0036), time to progression (miR-139-3p (HR: 1.48, 95% CI: 1.13–1.94, p = 0.0047), miR-802 (HR: 0.48, 95% CI: 0.29–0.78, p = 0.0035)), progression free survival (miR-23a-5p (HR:1.32, 95% CI:1.09–1.61, p = 0.004), miR-23a-3p (HR:1.70, 95% CI:1.15–2.51, p = 0.0074), miR-802 (HR: 0.48, 95% CI: 0.29–0.80, p = 0.0048)), and resistance to chemotherapy (miR-1234 (HR: 0.26, 95% CI: 0.11–0.64, p = 0.003)). A few miRNAs identified in our training cohort, were validated in external cohorts with similar results.

Conclusion

Eight miRNAs were identified as significant predictors of overall survival, progression free survival, time to progression, and chemotherapy resistance. A number of these miRNAs were significantly validated using external datasets. Inter-platform and inter-laboratory variations may have influence on the ability to compare and reproduce miRNA results. The use of miRNAs as potential markers of relapse and survival in ovarian cancer warrants further investigation.

Intronic miR-744 Inhibits Glioblastoma Migration by Functionally Antagonizing Its Host Gene MAP2K4

Background: The second intron of Mitogen-Activated Protein Kinase Kinase 4 (MAP2K4), an important hub in the pro-invasive MAPK pathway, harbors miR-744. There is accumulating evidence that intronic micro-RNAs (miRNAs) are capable of either supporting or restraining functional pathways of their host genes, thereby creating intricate regulative networks. We thus hypothesized that miR-744 regulates glioma migration by interacting with its host’s pathways. Methods: Patients’ tumor specimens were obtained stereotactically. MiR-744 was overexpressed in U87, T98G, and primary glioblastoma (GBM) cell lines. Cell mobility was studied using migration and Boyden chamber assays. Protein and mRNA expression was quantified by SDS-PAGE and qRT-PCR. Interactions of miR-744 and 3’UTRs were analyzed by luciferase reporter assays, and SMAD2/3, p38, and beta-Catenin activities by TOP/FOPflash reporter gene assays. Results: As compared to a normal brain, miR-744 levels were dramatically decreased in GBM samples and in primary GBM cell lines. Astrocytoma WHO grade II/III exhibited intermediate expression levels. Re-expression of miR-744 in U87, T98G, and primary GBM cell lines induced focal growth and impaired cell mobility. Luciferase activity of 3’UTR reporter constructs revealed the pro-invasive factors TGFB1 and DVL2 as direct targets of miR-744. Re-expression of miR-744 reduced levels of TGFB1, DVL2, and the host MAP2K4, and mitigated activity of TGFB1 and DVL2 downstream targets SMAD2/3 and beta-Catenin. TGFB1 knock-down repressed MAP2K4 expression. Conclusion: MiR-744 acts as an intrinsic brake on its host. It impedes MAP2K4 functional pathways through simultaneously targeting SMAD-, beta-Catenin, and MAPK signaling networks, thereby strongly mitigating pro-migratory effects of MAP2K4. MiR-744 is strongly repressed in glioma, and its re-expression might attenuate tumor invasiveness.

Long non-coding RNA CASC15 promotes tongue squamous carcinoma progression through targeting miR-33a-5p

Long non-coding RNAs (lncRNAs) have gained a lot of attention because they participate in several human disorders, including tumors. This study determined the role of LncRNA CASC15 (cancer susceptibility candidate 15) in the development of tongue squamous cell carcinoma (TSCC). Here, we identified that CASC15 expression was upregulated in TSCC samples and cell lines. We showed that overexpression of CASC15 promoted cell proliferation, cycle, and migration in TSCC. In addition, we revealed that miR-33a-5p expression was downregulated in TSCC tissues and cell lines. Moreover, we showed that the expression of CASC15 was negatively related with miR-33a-5p expression in TSCC tissues. Ectopic expression of miR-33a-5p suppressed cell proliferation, cycle, and migration in TSCC. Elevated expression of CASC15 suppressed miR-33a-5p expression and promoted ZEB1 expression in SCC4 cell. Ectopic expression of CASC15 promoted TSCC cell proliferation, cycle, and migration through targeting miR-33a-5p. These results suggested that lncRNA CASC15 and miR-33a-5p might be exploited as new markers of TSCC and were potential treatment targets for TSCC patients.

MicroRNA-488 inhibits tongue squamous carcinoma cell invasion and EMT by directly targeting ATF3

BACKGROUND

It has been reported that the expression of activating transcription factor 3 (ATF3) is closely associated with both microRNA (miRNA) processing and the progress of many cancers. Our study aimed to explore the interaction between ATF3 and miR-488 in tongue squamous cell carcinoma (TSCC).

METHODS

Quantitative real-time PCR was performed to detect the levels of ATF3 and miR-488 in TSCC tissues and cell lines. Cell invasion and epithelial-mesenchymal transition (EMT) were assessed to determine the biological functions of miR-488 and ATF3 in TSCC cells. The mRNA and protein levels of ATF3 were measured using quantitative RT-PCR and western blotting. Luciferase assays were performed to validate ATF3 as an miR-488 target in TSCC cells.

RESULTS

We found that the level of miR-488 significantly decreased and the expression of ATF3 significantly increased in TSCC tissues and cell lines. A low level of miR-488 was closely associated with increased expression of ATF3 in TSCC tissues. Introducing miR-488 significantly inhibited the invasion and EMT of TSCC cells, and knockdown of miR-488 promoted both processes. The bioinformatics analysis predicted that ATF3 is a potential target gene of miR-488. The luciferase reporter assay showed that miR-488 could directly target ATF3. ATF3 silencing had similar effects to miR-488 overexpression on TSCC cells. Overexpression of ATF3 in TSCC cells partially reversed the inhibitory effects of the miR-488 mimic.

CONCLUSION

miR-488 inhibited cell invasion and EMT of TSCC cells by directly downregulating ATF3 expression.

eNOS expression and NO release during hypoxia is inhibited by miR-200b in human endothelial cells

The nitric oxide (NO) secreted by vascular endothelium is required for the maintenance of cardiovascular homeostasis. Diminished release of NO generated by endothelial NO synthase contributes to endothelial dysfunction. Hypoxia and ischemia reduce endothelial eNOS expression via posttranscriptional mechanisms that result in NOS3 transcript destabilization. Here, we examine whether microRNAs contribute to this mechanism. We followed the kinetics of hypoxia-induced changes in NOS3 mRNA and eNOS protein levels in primary human umbilical vein endothelial cells (HUVECs). Utilizing in silico predictive protocols to identify potential miRNAs that regulate eNOS expression, we identified miR-200b as a candidate. We established the functional miR-200b target sequence within the NOS3 3′UTR, and demonstrated that manipulation of the miRNA levels during hypoxia using miR-200b mimics and antagomirs regulates eNOS levels, and established that miR-200b physiologically limits eNOS expression during hypoxia. Furthermore, we demonstrated that the specific ablation of the hypoxic induction of miR-200b in HUVECs restored eNOS-driven hypoxic NO release to the normoxic levels. To determine whether miR-200b might be the only miRNA that had this effect, we utilized Next Generation Sequencing (NGS) to follow hypoxia-induced changes in the miRNA levels in HUVECS and found 83 novel hypoxamiRs, with two candidate miRNAs besides miR-200b that could potentially influence eNOS levels. Taken together, the data establish miR-200b-eNOS regulation as a first hypoxamiR-based mechanism that limits NO bioavailability during hypoxia in endothelial cells, and show that hypoxamiRs could become useful therapeutic targets for cardiovascular diseases and other hypoxic-related diseases including various types of cancer.

Functional Roles of Sex-Biased, Growth Hormone-Regulated MicroRNAs miR-1948 and miR-802 in Young Adult Mouse Liver

Sex-specific temporal patterns of pituitary growth hormone (GH) secretion determine the sex-biased transcription of hundreds of genes in the liver and impart important sex differences in liver physiology, metabolism, and disease. Sex differences in hepatic gene expression vary widely, ranging from less than twofold to >1000-fold in the mouse. Here, we use small RNA sequencing to discover 24 sex-biased mouse liver microRNAs (miRNAs), and then investigate the roles of two of these miRNAs in GH-regulated liver sex differences. Studies in prepubertal and young adult mice, and in mice in which pituitary hormones are ablated or where sex-specific hepatic GH signaling is dysregulated, demonstrated that the male-biased miR-1948 and the female-biased miR-802 are both regulated by sex-specific pituitary GH secretory patterns, acquire sex specificity at puberty, and are dependent on the GH-activated transcription factor STAT5 for their sex-specific expression. Both miRNAs are within genomic regions characterized by sex-biased chromatin accessibility. miR-1948, an uncharacterized miRNA, has essential features for correct Drosha/Dicer processing, generates a bona fide mature miRNA with strong strand bias for the 5p arm, and is bound by Argonaute in liver tissue, as is miR-802. In vivo studies using inhibitory locked nucleic acid sequences revealed that miR-1948-5p preferentially represses female-biased messenger RNAs (mRNAs) and induces male-biased mRNAs in male liver; conversely, miR-802-5p preferentially represses male-biased mRNAs and increases levels of female-biased mRNAs in female liver. Cytochrome P450 mRNAs were strongly enriched as targets of both miRNAs. Thus, miR-1948-5p and miR-802-5p are functional components of the GH regulatory network that shapes sex-differential gene expression in mouse liver.

MicroRNA‑136 inhibits prostate cancer cell proliferation and invasion by directly targeting mitogen‑activated protein kinase kinase 4

Prostate cancer (PCa) is the second most common type of cancer and the 6th leading cause of cancer‑associated mortality worldwide. Accumulated evidence suggests that PCa initiation and progression are controlled by microRNAs (miRNAs). Therefore, investigating PCa‑associated miRNAs may provide novel biomarkers for the diagnosis and treatment of patients with PCa. In the present study it was demonstrated that miRNA‑136 (miR‑136) expression was significantly downregulated in PCa tissues and cell lines. The resumption of miR‑136 expression suppressed cell proliferation and invasion in PCa cells. Bioinformatics analysis predicted that mitogen‑activated protein kinase kinase 4 (MAP2K4) was a direct target of miR‑136. This prediction was experimentally confirmed by a luciferase reporter assay, RT‑qPCR and western blot analysis. MAP2K4 was highly expressed in PCa tissues and inversely correlated with the miR‑136 expression level. Additionally, the restoration of MAP2K4 expression significantly blocked the inhibitory effects of miR‑136 on cell proliferation and invasion in PCa cells. Therefore, miR‑136 may suppress the proliferation and invasion of PCa cells by targeting MAP2K4 and may be a novel candidate target for cancer therapy against PCa.

microRNA-802 is involved in palmitate-induced damage to pancreatic β cells through repression of sirtuin 6

Free fatty acid (FFA)-induced pancreatic β-cell loss is implicated in the pathogenesis of type 2 diabetes mellitus (T2DM). It has been documented that circulating microRNA (miR)-802 levels are significantly greater in T2DM patients than in healthy subjects. However, the role of miR-802 in FFA-induced damage to β cells is still unclear. In the present study, we measured the expression of miR-802 in the INS-1 rat insulinoma cell line after palmitate treatment for 48 h. Gain- and loss-of-function studies were conducted to determine the function of miR-802 in palmitate-induced apoptosis and reactive oxygen species (ROS) production. The target gene(s) of miR-802 was functionally characterized. Compared to control cells, palmitate treatment caused a time- and concentration-dependent induction of miR-802 in INS-1 cells. Knockdown of miR-802 significantly blocked palmitate-induced apoptosis and attenuated ROS formation. Moreover, miR-802 downregulation prevented the reduction of prosurvival proteins Mcl-1 and Bcl-xL by palmitate. In contrast, ectopic expression of miR-802 stimulated apoptosis and ROS generation in INS-1 cells. Sirtuin 6 (SIRT6) was identified to be a direct target gene of miR-802. Overexpression of miR-802 suppressed the expression of SIRT6. Enforced expression of SIRT6 abolished the induction of apoptosis and ROS production by miR-802. Taken together, miR-802 is required for palmitate-induced damage to β cells by targeting SIRT6 and represents a potential therapeutic target for T2DM.

Overexpression of Chromosome 21 miRNAs May Affect Mitochondrial Function in the Hearts of Down Syndrome Fetuses

Dosage-dependent upregulation of most of chromosome 21 (Hsa21) genes has been demonstrated in heart tissues of fetuses with Down syndrome (DS). Also miRNAs might play important roles in the cardiac phenotype as they are highly expressed in the heart and regulate cardiac development. Five Hsa21 miRNAs have been well studied in the past: miR-99a-5p, miR-125b-2-5p, let-7c-5p, miR-155-5p, and miR-802-5p but few information is available about their expression in trisomic tissues. In this study, we evaluated the expression of these miRNAs in heart tissues from DS fetuses, showing that miR-99a-5p, miR-155-5p, and let-7c-5p were overexpressed in trisomic hearts. To investigate their role, predicted targets were obtained from different databases and cross-validated using the gene expression profiling dataset we previously generated for fetal hearts. Eighty-five targets of let-7c-5p, 33 of miR-155-5p, and 10 of miR-99a-5p were expressed in fetal heart and downregulated in trisomic hearts. As nuclear encoded mitochondrial genes were found downregulated in trisomic hearts and mitochondrial dysfunction is a hallmark of DS phenotypes, we put special attention to let-7c-5p and miR-155-5p targets downregulated in DS fetal hearts and involved in mitochondrial function. The let-7c-5p predicted target SLC25A4/ANT1 was identified as a possible candidate for both mitochondrial and cardiac anomalies.

MicroRNA-802 plays a tumour suppressive role in tongue squamous cell carcinoma through directly targeting MAP2K4

OBJECTIVES

Tongue squamous cell carcinoma (TSCC) is the most common oral tumours. MicroRNAs play crucial roles in many cell processes including cell viability, development, apoptosis, migration and invasion. The role of miR-802 in the TSCC is still unknown.

MATERIALS AND METHODS

The miR-802 expression in TSCC tissues and cell lines was determined by quantitative real-time polymerase chain reaction. CCK-8 assay was performed to measure the cell viability, while the cell invasion assay was used to determine the cell invasion. Dual-luciferase reporter and western blot were used to confirm the potential target gene of miR-802.

RESULTS

In our study, we demonstrated that miR-802 expression was downregulated in TSCC tissues and cell lines. Elevated expression of miR-802 suppressed the TSCC cell viability and invasion. Moreover, enforced expression of miR-802 increased the expression of E-cadherin, while suppressed the expression of N-cadherin, Snail and Vimentin in the TSCC cell. In addition, we identified the mitogen-activated protein kinase 4 (MAP2K4) as a direct target gene of miR-802 in the TSCC cell. We also demonstrated that the expression of MAP2K4 was higher in the TSCC tissues than that in the adjacent normal tissues. Furthermore, the expression level of MAP2K4 was inversely associated with the expression of miR-802 in TSCC tissues. We also demonstrated that the MAP2K4 expression was upregulated in TSCC cell lines. Elevated expression of miR-802 inhibited TSCC cell viability and invasion through inhibiting MAP2K4 expression.

CONCLUSIONS

Our data revealed that miR-802 played as a tumour suppressor gene and might act as a therapeutic target in TSCC patients.