MicroRNA-452 suppresses pancreatic cancer migration and invasion by directly targeting B-cell-specific Moloney murine leukemia virus insertion site 1

MicroRNA-452: a double-edged sword in multiple human cancers

MicroRNAs (miRNAs) are small, noncoding RNAs with important functions in development, cell differentiation, and regulation of cell cycle and apoptosis. MiRNA expression is deregulated in various pathological processes including tumorigenesis and cancer progression through various mechanisms including amplification or deletion of miRNA genes, mutations, and epigenetic silencing and defects in the miRNA biogenesis machinery. Several studies have now shown abnormal miRNA profiles and proved their involvement in the initiation and progression of cancer. Since miR-452 has diverse roles (as suppressor or oncogene) in different cellular processes including epithelial-mesenchymal transition (EMT), proliferation, migration, and invasion, in this review we highlight a brief overview of the biological function and regulatory mechanism of miR-452 and its involvement as a potential biomarker for diagnosis and treatment of various cancer types.

Overexpression of MiR-452-5p in hepatocellular carcinoma tissues and its prospective signaling pathways

BACKGROUND

The implication of miR-452-5p and its prospective machinery in hepatocellular carcinoma (HCC) remains largely unknown. For this reason, this study aimed to inspect the clinical implication of miR-452-5p expression in HCC tissues with multiple detection approaches, to analyze its potential function via in silico methods, and to validate this using a dual-luciferase reporter assay.

METHODS

The assessment of the expression level of miR-452-5p in HCC was conducted via four methods: 1) in-house real-time quantitative PCR (RT-qPCR), 2) miRNA-sequencing (miRNA-seq) from The Cancer Genome Atlas (TCGA), 3) miRNA microarrays from the Gene Expression Omnibus (GEO), and 4) comprehensive meta-analyses calculating the standard mean difference (SMD) and summary of receiver operator characteristic (sROC). Following the target prediction, one of the potential targets of miR-452-5p was validated through a dual-luciferase reporter assay.

RESULTS

MiR-452-5p was consistently elevated in HCC tissues via various detection methods, including in-house RT-qPCR, miRNA-seq, and miRNA microarrays. The final SMD was 0.842 for 820 cases of HCC samples. Simultaneously, the area under curve (AUC) of the sROC was 0.80 (0.76-0.83). The 1,135 predicted targets of miR-452-5p were enriched in the pathways of cytokine-cytokine receptor interaction, carbon metabolism, and complement and coagulation cascades. Among these predicted targets, CDKN1B was verified to be a real target of miR-452-5p.

CONCLUSION

The overexpression of miR-452-5p may play a pivotal role in the carcinogenesis of HCC via targeting multiple signaling pathways and genes. The function and molecular machinery of miR-452-5p in HCC requires further in-depth exploration.

Intermittent Hypoxia Up-Regulates CCL2, RETN, and TNFα mRNAs in Adipocytes via Down-regulation of miR-452

Sleep apnea syndrome (SAS), characterized by recurrent episodes of oxygen desaturation and reoxygenation (intermittent hypoxia [IH]), is a risk factor for insulin resistance. Recently, IH is considered to independently cause adipose tissue inflammation/dysfunction, leading to worsening insulin resistance; however, the detailed mechanism remains unknown. We exposed mouse 3T3-L1 and human SW872 adipocytes to experimental IH or normoxia for 24 h, and analyzed mRNA expression of several adipokines. We found that the mRNA levels of RETN, TNFα, and CCL2 in SW872 and 3T3-L1 adipocytes were significantly increased by IH, whereas the promoter activities of these genes were not increased. A target mRNA search of microRNA (miR)s revealed that all human mRNAs have a potential target sequence for miR-452. The miR-452 level of IH-treated cells was significantly decreased compared to normoxia-treated cells. MiR-452 mimic and non-specific control RNA (miR-452 mimic NC) were introduced into SW872 cells, and the IH-induced up-regulation of the genes was abolished by introduction of the miR-452 mimic but not by the miR-452 mimic NC. These results indicate that IH stress down-regulates the miR-452 in adipocytes, resulting in increased levels of RETN, TNFα, and CCL2 mRNAs, leading to insulin resistance in SAS patients.

Identification of a nine-miRNA signature for the prognosis of Uveal Melanoma

The present study aims to construct a miRNA-based predictive signature of Uveal melanoma (UM) based on the database of the cancer genome atlas (TCGA). We obtained miRNA expression profiles and clinical information of 80 UM patients from TCGA, and randomly divided them into a training and a testing set. After data processing and forward screening, a total of 204 miRNAs with prognostic value were then examined by the Cox proportional hazard regression model in the training set. Receiver operating curve (ROC) analysis was applied to validate the accuracy of the signature. The biological relevance of putative miRNA target genes was also analyzed using the bioinformatics method. As a result, a linear prognostic model consisting of 9 miRNAs (miR-195, miR-224, miR-365a, miR-365b, miR-452, miR-4709, miR-7702, miR-513c, miR-873) was developed to divide UM patients into a high- and a low-risk group. Patients assigned to the high-risk group had significantly shorter overall survival than those in the low-risk group, which was further confirmed by the Area under curve (AUC) value of 0.858 at 5 year obtained from ROC. Gene Ontology (GO) analysis indicated that predicted target genes of these miRNAs are primarily associated with the modulation of protein expression and function, such as the activity of ubiquitin protein ligase and protein kinase. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that these genes were involved in multiple signaling pathways linked to carcinogenesis. The tumor specific 9-miRNA signature was also verified in the testing and entire set. In summary, based on UM data of TCGA, we identified and validated a 9-miRNA-based prognostic signature.

MicroRNAs in pancreatic cancer diagnosis and therapy

Pancreatic cancer remains a disease with very poor prognosis (only 5-6% of patients are still alive after five years). Attempts to improve the results of treatment of pancreatic cancer focus on a better understanding of the pathogenesis, and non-invasive diagnostic methods (genetic testing from peripheral blood), which would create the possibility of early diagnosis and early surgical treatment before the onset of metastasis. New hopes for the improvement of early diagnosis and treatment of pancreatic ductal adenocarcinoma (PDAC) are associated with genetic testing of microRNA expression changes. A large body of evidence has revealed that microRNAs are aberrantly expressed in the serum and in cancer tissues and elicit oncogenic or tumour-suppressive functions. Selected microRNAs can distinguish pancreatic ductal adenocarcinoma from non-cancerous lesions of the pancreas. This review focuses on the involvement of microRNAs in the early diagnosis of pancreatic cancer. Research results related to the development of a novel therapeutic strategy based on the modulation of microRNA expressions for a better outcome in patients with pancreatic cancer are also presented.

MicroRNA‑874 inhibits proliferation and invasion of pancreatic ductal adenocarcinoma cells by directly targeting paired box 6

Studies have demonstrated that a number of microRNAs (miRNAs) are dysregulated in pancreatic ductal adenocarcinoma (PDAC), and alterations in their expression may affect the onset and progression of PDAC. Therefore, the expression patterns, biological functions and associated molecular mechanisms of miRNAs in PDAC should be elucidated for the development of novel therapeutic methods. Previous studies reported significant miRNA‑874 (miR‑874) dysregulation in multiple types of human cancer. However, the expression pattern, possible roles and underlying mechanisms of miR‑874 in PDAC remain to be elucidated. This study evaluated miR‑874 expression in PDAC and examined its biological functions and underlying mechanism of action in PDAC progression. miR‑874 expression was downregulated in PDAC tissues and cell lines. Functional experiments demonstrated that upregulation of miR‑874 inhibited cell proliferation and invasion in PDAC. Additionally, paired box 6 (PAX6) was predicted as a putative target of miR‑874 using bioinformatics analysis. Further experiments demonstrated that PAX6 may be the direct target gene of miR‑874 in PDAC. PAX6 knockdown exhibited similar inhibitory effects to miR‑874 overexpression in PDAC cells. In addition, restored PAX6 expression may reverse the suppressive roles of miR‑874 overexpression in PDAC cells. The results demonstrated that miR‑874 may serve tumor suppressive roles in PDAC by directly targeting PAX6. Therefore, miR‑874 may exhibit potential applications for treatment of patients with PDAC.