Decreased expression of microRNA-206 correlates with poor clinical outcome in patients with malignant astrocytomas

Metabolic Roles of HIF1, c-Myc, and p53 in Glioma Cells

The metabolic reprogramming that promotes tumorigenesis in glioblastoma is induced by dynamic alterations in the hypoxic tumor microenvironment, as well as in transcriptional and signaling networks, which result in changes in global genetic expression. The signaling pathways PI3K/AKT/mTOR and RAS/RAF/MEK/ERK stimulate cell metabolism, either directly or indirectly, by modulating the transcriptional factors p53, HIF1, and c-Myc. The overexpression of HIF1 and c-Myc, master regulators of cellular metabolism, is a key contributor to the synthesis of bioenergetic molecules that mediate glioma cell transformation, proliferation, survival, migration, and invasion by modifying the transcription levels of key gene groups involved in metabolism. Meanwhile, the tumor-suppressing protein p53, which negatively regulates HIF1 and c-Myc, is often lost in glioblastoma. Alterations in this triad of transcriptional factors induce a metabolic shift in glioma cells that allows them to adapt and survive changes such as mutations, hypoxia, acidosis, the presence of reactive oxygen species, and nutrient deprivation, by modulating the activity and expression of signaling molecules, enzymes, metabolites, transporters, and regulators involved in glycolysis and glutamine metabolism, the pentose phosphate cycle, the tricarboxylic acid cycle, and oxidative phosphorylation, as well as the synthesis and degradation of fatty acids and nucleic acids. This review summarizes our current knowledge on the role of HIF1, c-Myc, and p53 in the genic regulatory network for metabolism in glioma cells, as well as potential therapeutic inhibitors of these factors.

MicroRNA-206 has a bright application prospect in the diagnosis of cases with oral cancer

Previous studies have shown that microRNA‐206 (miR‐206) exhibits anti‐tumour properties in various tumours. Nevertheless, diagnostic significance of miR‐206 in oral cancer is still poorly known. Our research was carried out to explore the performance of miR‐206 in the diagnosis of oral cancer. Quantitative real‐time polymerase chain reaction (qRT‐PCR) method was adopted to measure the level of miR‐206 in serum specimens from oral cancer cases and control individuals. Chi‐square test was performed to analyse the correlation between miR‐206 level and clinicopathological parameters of the cases. Receiver operating characteristic (ROC) curve was constituted to assess diagnostic accuracy of miR‐206 in oral cancer. Serum miR‐206 level in oral cancer patients was significantly lower than that in control individuals (P < .001). miR‐206 expression was obviously related to T classification (P = .033), TNM stage (P = .008) and lymph node metastasis (P = .028). The area under the curve (AUC) of the ROC curve was 0.846 (95% CI = 0.797‐0.896, P < .001) with a specificity of 72.7% and a sensitivity of 81.2%. It revealed that miR‐206 might be a non‐invasive indicator in differentiating oral cancer cases from control individuals. Down‐regulation of miR‐206 is related to the development of oral cancer. Serum miR‐206 might be an effective indicator for early detection of oral cancer.

Antioncogenic Effect of MicroRNA-206 on Neck Squamous Cell Carcinoma Through Inhibition of Proliferation and Promotion of Apoptosis and Autophagy

Recent studies have reported the crucial role of stanniocalcin-2 (STC2) in hepatocellular carcinoma; however, its role in head and neck squamous cell carcinoma (HNSCC) remains elusive. In this study, microRNA-206 (miR-206) was predicted to target STC2 gene. The study herein aimed to elucidate the effect of miR-206 on HNSCC by targeting STC2. STC2 was highly expressed in HNSCC tissues and cells. By targeting STC2, miR-206 decreased mRNA and protein expression of STC2. Importantly, our study showed that miR-206 blocked the Akt signaling pathway by inhibiting STC2. Intriguingly, our data from in vitro and in vivo experiments suggested that miR-206 overexpression led to decreased cell proliferation and increased cell apoptosis and autophagy, as well as suppressed tumor growth; whereas, STC2 silencing reversed the effects of miR-206 inhibitor on those biological behaviors. In this study, we investigated the antioncogenic effect of miR-206 on HNSCC by targeting STC2, and highlighted miR-206/STC2 aixs as potential therapeutic targets for HNSCC.

Prognostic Value and Clinicopathological Features of MicroRNA-206 in Various Cancers: A Meta-Analysis

It has been reported that microRNA-206(miR-206) plays an important role in cancers and could be used as a prognostic biomarker. However, the results are controversial. Therefore, we summarize all available evidence and present a meta-analysis to estimate the prognostic value of miR-206 in various cancers. The relevant studies were collected by searching PubMed, EMBASE, and Web of Science databases until August 21, 2020. Hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) were applied to explore the association between miR-206 and survival results and clinicopathologic features. Sources of heterogeneity were investigated by subgroup analysis and sensitivity analysis. Publication bias was evaluated using Egger's test. Twenty articles involving 2095 patients were included in the meta-analysis. The pooled HR showed that low miR-206 expression was significantly associated with unfavourable overall survival (OS) (HR = 2.03, 95 CI%: 1.53-2.70, P < 0.01). In addition, we found that low miR-206 expression predicted significantly negative association with tumor stage (III-IV VS. I-II) (OR = 4.20, 95% CI: 2.17-8.13, P < 0.01), lymph node status (yes VS. no) (OR = 3.58, 95%: 1.51-8.44, P = 0.004), distant metastasis (yes VS. no) (OR = 3.19, 95%: 1.07-9.50, P = 0.038), and invasion depth (T3 + T4 vs. T2 + T1) (OR = 2.43, 95%: 1.70-3.49, P < 0.01). miR-206 can be used as an effective prognostic indicator in various cancers. Further investigations are warranted to validate the present results.

Propofol Inhibits the Migration and Invasion of Glioma Cells by Blocking the PI3K/AKT Pathway Through miR-206/ROCK1 Axis

Background

Propofol has been identified to perform anti-tumor functions in glioma. However, the molecular mechanisms underlying propofol-induced prevention on migration and invasion of glioma cells remain unclear.

Methods

Cell proliferation, invasion and migration were measured by 3-(4,5)-dimethylthiahiazo(−z-y1)-3,5-di-phenytetrazoliumromide assay and transwell assay, respectively. The expression of microRNA (miR)-206 and Rho-associated coiled coil-containing protein kinase 1 (ROCK1) was detected by quantitative real-time polymerase chain reaction. Western blot was used to measure the activation of the PI3K/AKT pathway. The interaction between miR-206 and ROCK1 was analyzed using the dual-luciferase reporter assay, RNA immunoprecipitation assay, and pull-down assay.

Results

Propofol treatment inhibited the migration, invasion, and PI3K/AKT pathway activation in glioma cells. MiR-206 was decreased in glioma tissues and cells, while propofol exposure induced the upregulation of miR-206 in glioma cells. Besides that, we also found overexpressed miR-206 enhanced propofol-mediated inhibition on the migration, invasion, and PI3K/AKT pathway activation of glioma cells. Subsequently, ROCK1 was confirmed to be a target of miR-206. ROCK1 was elevated in glioma tissues and cells, but was reduced by propofol exposure in glioma cells. The rescue assay indicated that the miR-206/ROCK1 axis was involved in propofol-induced inhibition on the migration, invasion, and PI3K/AKT pathway activation in glioma cells.

Conclusion

Propofol inhibited the migration and invasion of glioma cells by blocking the PI3K/AKT pathway through the miR-206/ROCK1 axis, suggesting an effective clinical implication for the anesthetic to prevent the metastasis of glioma.

MiR-206 inhibits HGF-induced epithelial-mesenchymal transition and angiogenesis in non-small cell lung cancer via c-Met /PI3k/Akt/mTOR pathway

MiR-206 is low expression in lung cancers and associated with cancer metastasis. However, the roles of miR-206 in epithelial-mesenchymal transition (EMT) and angiogenesis in lung cancer remain unknown. In this study, we find that hepatocyte growth factor (HGF) induces EMT, invasion and migration in A549 and 95D lung cancer cells, and these processes could be markedly inhibited by miR-206 overexpression. Moreover, we demonstrate that miR-206 directly targets c-Met and inhibits its downstream PI3k/Akt/mTOR signaling pathway. In contrast, miR-206 inhibitors promote the expression of c-Met and activate the PI3k/Akt/mTOR signaling, and this effect could be attenuated by the PI3K inhibitor. Moreover, c-Met overexpression assay further confirms the significant inhibitory effect of miR-206 on HGF-induced EMT, cell migration and invasion. Notably, we also find that miR-206 effectively inhibits HGF-induced tube formation and migration of human umbilical vein endothelial cells (HUVECs), and the mechanism is also related to inhibition of PI3k/Akt/mTOR signaling. Finally, we reveal the inhibitory effect of miR-206 on EMT and angiogenesis in xenograft tumor mice model. Taken together, miR-206 inhibits HGF-induced EMT and angiogenesis in lung cancer by suppressing c-Met/PI3k/Akt/mTOR signaling. Therefore, miR-206 might be a potential target for the therapeutic strategy against EMT and angiogenesis of lung cancer.

Role of the microRNA, miR-206, and its target PIK3C2α in endothelial progenitor cell function – potential link with coronary artery disease

Coronary artery disease is a major cause of morbidity and mortality worldwide. Impaired endothelial function and integrity are major contributory factors to coronary artery disease. MicroRNAs have been proposed to play an important role in coronary artery disease pathogenesis. In the present study, the expression of miR-206 was found to be significantly upregulated in peripheral blood endothelial progenitor cells from patients with coronary artery disease compared to healthy donors. MiR-206 was found to regulate endothelial progenitor cell activities by targeting the protein kinase PIK3C2α, which showed decreased expression in coronary artery disease endothelial progenitor cells. Knockdown of miR-206 in coronary artery disease endothelial progenitor cells rescued their angiogenic and vasculogenic abilities both in vitro and in vivo in a mouse ischemic hindlimb model. Furthermore, knockdown of miR-206 activated not only PIK3C2α, but also the angiogenic signal modulators Akt and endothelial nitric oxide synthase. It is therefore proposed that repression of the phosphoinositide 3-kinase/Akt/endothelial nitric oxide synthase signal transduction pathway by miR-206 downregulates angiogenesis contributing to the pathophysiology of coronary artery disease.

Decreased expression of microRNA-107 predicts poorer prognosis in glioma

The expression level of microRNA-107 (miR-107) has been proved to be decreased in many human malignant cancers. Especially in glioma, accumulating evidence indicates that miR-107 may play important parts in cell proliferation, apoptosis, and invasion in glioma. However, its clinical significance in glioma has not been investigated. This study aims at investigating the relationship between miR-107 expression level and clinical significance and analyzing its value of miR-107 in valuing the prognosis of glioma patients. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure the expression of miR-107 in 80 glioma and 17 normal brain tissues. The results showed the miR-107 expression level in glioma tissues was significantly lower than those in normal brain tissues (p < 0.001). The decreased expression of miR-107 in glioma was positively associated with high WHO grade (p < 0.001), low Karnofsky performance score (KPS) (p < 0.001), and large tumor size (p < 0.001) and had a significant impact on overall survival (OS) (p < 0.001) and progression-free survival (PFS) (p < 0.001) according to Kaplan-Meier survival with log-rank test. Finally, Cox regression analyses showed that low miR-107 expression (p < 0.001) might be an independent prognostic parameter to predict poor prognosis. In conclusion, it is the first data to prove that expression level of miR-107 may be a novel and valuable prognostic factor in glioma.

Prognostic significance of combined microRNA-206 and CyclinD2 in gastric cancer patients after curative surgery: A retrospective cohort study

AIM

To investigate associations of microRNA (miR)-206 and CyclinD2 (CCND2) expression, alone or in combination, with clinicopathological characteristics and patients' prognosis in gastric cancer.

METHODS

MiR-206 and CCND2 mRNA expression levels were detected by real-time quantitative RT-PCR in 220 self-pairs of gastric cancer and adjacent non-cancerous tissues.

RESULTS

Compared with the adjacent non-cancerous tissues, the expression levels of miR-206 and CCND2 mRNA were respectively reduced and elevated in gastric cancer tissues dramatically (both P<0.001). Notably, the expression levels of miR-206 in gastric cancer tissues were negatively correlated with those of CCND2 mRNA significantly (r=-0.463, P<0.001). Then, statistical analysis showed that low miR-206 expression and high CCND2 expression, alone or in combination, were all significantly associated with great depth of invasion, positive lymph node and distant metastases, and advanced TNM stage of human gastric cancer (all P<0.05). After that, we also found that the overall survivals of the patients with low miR-206 expression and high CCND2 expression were respectively shorter than those with high miR-206 expression and low CCND2 expression. More interestingly, miR-206-low/CCND2-high expression was associated with a significantly worst overall survival of all miR-206/CCND2 groups (P<0.001). Furthermore, multivariate analysis identified miR-206 and/or CCND2 expression as independent prognostic factors for overall survival in patients with gastric cancer.

CONCLUSION

Our data provide evidence that the dysregulation of miR-206-CCND2 axis may contribute to the aggressive progression and poor prognosis of human gastric cancer in clinical settings. Combined detection of their expression might be particularly helpful for surveillance of disease progression and treatment stratification.

Brain microRNAs and insights into biological functions and therapeutic potential of brain enriched miRNA-128

MicroRNAs, the non-coding single-stranded RNA of 19–25 nucleotides are emerging as robust players of gene regulation. Plethora of evidences support that the ability of microRNAs to regulate several genes of a pathway or even multiple cross talking pathways have significant impact on a complex regulatory network and ultimately the physiological processes and diseases. Brain being a complex organ with several cell types, expresses more distinct miRNAs than any other tissues. This review aims to discuss about the microRNAs in brain development, function and their dysfunction in brain tumors. We also provide a comprehensive summary of targets of brain specific and brain enriched miRNAs that contribute to the diversity and plasticity of the brain. In particular, we uncover recent findings on miRNA-128, a brain-enriched microRNA that is induced during neuronal differentiation and whose aberrant expression has been reported in several cancers. This review describes the wide spectrum of targets of miRNA-128 that have been identified till date with potential roles in apoptosis, angiogenesis, proliferation, cholesterol metabolism, self renewal, invasion and cancer progression and how this knowledge might be exploited for the development of future miRNA-128 based therapies for the treatment of cancer as well as metabolic diseases.