Potential value of MicroRNA-21 as a biomarker for predicting the prognosis of patients with breast cancer: A protocol for meta-analysis and bioinformatics analysis

BACKGROUND

The latest global cancer data from 2020 shows that breast cancer has replaced lung cancer as the number one cancer in the world. Searching for new biomarkers of breast cancer has important clinical significance for early diagnosis, prediction of prognosis, and targeted therapy. MicroRNA-21 (miRNA-21) can be used as a new molecular marker for early diagnosis, prognosis, and treatment of tumors. However, the expression of miRNA-21 in breast cancer and its prognosis are not clear. Therefore, this study conducted a meta-analysis to further clarify the relationship between the expression of miRNA-21 in breast cancer and prognosis. At the same time, we carried out bioinformatics analysis to further analyze the possible molecular mechanism of miRNA-21, so as to provide potential clinical indicators for the diagnosis, treatment, and prognosis of patients.

METHODS

PubMed, Medline, Embase, Web of Science, Wanfang, Chinese Biomedical Literature Database, Chinese National Knowledge Infrastructure, and other databases were used to retrieve the published relevant literatures. Include the eligible research, extract the survival data hazard ratios and 95% confidence intervals and other information. STATA16.0 software was used for meta-analysis. Download the miRNA data of breast cancer through the Cancer Genome Atlas (TCGA) database and Gene Expression Omnibus (GEO) database. The data extracted for independent sample t test and ROC curve was drawn. OncomiR plotted the survival curve of miRNA-21 on the prognosis of breast cancer. The target genes of miRNA-21 were predicted, and the Gene Ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were analyzed. STRING database and Cytoscape construct protein-protein interaction (PPI) network to obtain Hub gene. The correlation between the expression level of Hub gene in breast cancer and the abundance of immune cell infiltration was analyzed by TIMER database and verified by Kaplan-Meien plotter database.

RESULTS

The results of this meta-analysis will be submitted to a peer-reviewed journal for publication.

CONCLUSION

In this study, meta-analysis and bioinformatics analysis were used to further explore the prognosis, mechanism, and related pathways of miRNA-21 in breast cancer.

ETHICS AND DISSEMINATION

The private information from individuals will not be published. This systematic review also should not damage participants' rights. Ethical approval is not available. The results may be published in a peer-reviewed journal or disseminated in relevant conferences.

OSF REGISTRATION NUMBER

DOI 10.17605/OSF.IO/R32A9.

The correlation of long non-coding RNA NEAT1 and its targets microRNA (miR)-21, miR-124, and miR-125a with disease risk, severity, and inflammation of allergic rhinitis

The present study aimed to investigate the correlation of long non-coding RNA nuclear-enriched abundant transcript 1 (lncRNA NEAT1) with microRNA (miR)-21, miR-124, and miR-125a, and their associations with disease risk, severity, and inflammatory cytokines of allergic rhinitis (AR).Totally 70 AR patients and 70 non-atopic obstructive snoring patients (as controls) were recruited. Inferior turbinate mucosa samples were collected from all participants for lncRNA NEAT1, its targets (miR-21, miR-124, and miR-125a), interleukin (IL)-4, IL-6, IL-10, and IL-17 detection via reverse transcription quantitative polymerase chain reaction. Disease severity of AR patients was assessed using individual nasal symptom score (INSS) and total nasal symptom score (TNSS).LncRNA NEAT1 was upregulated, while miR-21, miR-124, and miR-125a were downregulated in AR patients compared with controls. Additionally, lncRNA NEAT1, miR-21, and miR-125a displayed good values in differentiating AR patients from controls, while miR-124 could only slightly differentiate AR patients from controls. In AR patients, lncRNA NEAT1 was negatively associated with miR-21 and miR-125a, but not miR-124. However, in controls, no correlation of lncRNA NEAT1 with miR-21, miR-124, or miR-125a was observed. Furthermore, in AR patients, lncRNA NEAT1 was positively, while miR-21 and miR-125a was negatively associated with INSS (rhinorrhea, itching, congestion scores), TNSS and inflammatory cytokines; however, correlation of miR-124 with INSS, TNSS, and inflammatory cytokines was slight.LncRNA NEAT1 and its targets (miR-21 and miR-125a) present close correlations with disease risk, severity, and inflammation of AR, suggesting their potential as biomarkers for AR assessment.

Aberrant expression of miR-21 in patients with inflammatory bowel disease: A protocol for systematic review and meta analysis

BACKGROUND

microRNAs have drawn more attention due to their function on the inflammatory process. The association between microRNA-21 (miR-21) expression and risk of inflammatory bowel diseases (IBD) remain inconclusive. This study was aimed to acquire a more exact estimation of this relationship.

METHODS

Relevant studies were identified through searching PubMed, Embase, Wanfang, and China National Knowledge Infrastructure database. Pooled standardized mean difference and 95% confidence intervals were calculated using a random-effect model. Publication bias test, sensitivity analysis and subgroup analysis were carried out.

RESULTS

A total of 20 relevant articles comprising 540 patients with ulcerative colitis (UC), 459 patients with Crohn disease (CD) and 511 non-IBD controls were included in this analysis. The expression of miR-21 was significantly increased in colon tissue of both UC and CD patients compared with non-IBD controls. However, there were no significant differences between patients with UC and CD. Moreover, increased miR-21 expression was associated with disease activity status in UC patients, but not in CD patients.

CONCLUSIONS

This meta-analysis demonstrates that the higher miR-21 expression in colon tissue is positively associated with the development of UC and CD, and miR-21 might serve as a disease marker of IBD.

Low‑intensity ultrasound enhances the antitumor effects of doxorubicin on hepatocellular carcinoma cells through the ROS‑miR‑21‑PTEN axis

Hepatocellular carcinoma (HCC) is a type of liver cancer and is a leading cause of cancer-associated mortality. In China, ~466,000 patients are diagnosed with HCC and it is responsible for ~422,000 cases of mortality each year. Surgery is the most effective treatment available; however it is only suitable for patients with early-stage HCC. Chemotherapy has been confirmed as a necessary treatment for patients with advanced HCC, although drug resistance may limit its clinical outcome. Low intensity ultrasound (LIUS) represents a novel therapeutic approach to treat patients with HCC; however, its underlying molecular mechanism remains unclear. In the present study, cell viability, apoptosis and reactive oxygen species (ROS) generation were determined via Cell Counting Kit-8, flow cytometry and 2′,7′-dichlorofluorescein diacetate assays, respectively. The expression of miRNA in HCC cells following exposure to LIUS and doxorubicin (Dox) was analyzed using a microarray and reverse transcription-quantitative polymerase chain reaction analysis. It was revealed treatment with LIUS in combination with Dox was able to induce apoptosis of Huh7 cells, increasing the intracellular levels of reactive oxygen species (ROS) and malondialdehyde. Glutathione peroxidase and superoxide dismutase 1 are ROS-scavenging enzymes, which serve important roles in the oxidative balance, preventing oxidative stress. The protein expression levels of these two enzymes were significantly decreased following treatment with LIUS combined with Dox. The present results suggested that LIUS may decrease Dox resistance in HCC cells and that LIUS may be combined with chemotherapy to treat HCC. By performing microarray analysis, the expression levels of microRNA-21 (miR-21) were decreased following treatment with LIUS combined with Dox. Functional experiments showed that knockdown of miR-21 enhanced the antitumor activity of Dox, whereas overexpression of miR-21 reversed these effects. Phosphatase and tensin homolog (PTEN), a well-known tumor suppressor, was revealed to be a direct target of miR-21, and its translation was suppressed by miR-21. Finally, it was determined that combined treatment of LIUS and Dox induced anticancer effects by blocking the activation of the AKT/mTOR pathway, as demonstrated by the downregulation of phosphorylated (p-)AKT and p-mTOR; N-acetylcysteine, a general ROS inhibitor reversed the suppressive effects on the AKT/mTOR pathway mediated by LIUS and Dox. Collectively, the present results suggested that LIUS increased cell sensitivity to Dox via the ROS/miR-21/PTEN pathway. Chemotherapy combined with LIUS may represent a novel effective therapeutic strategy to treat patients with advanced HCC.

The relationship of MicroRNA-21 and plaque stability in acute coronary syndrome

Acute coronary syndrome (ACS) leads to clinical symptoms such as chest pain, dyspnea, and arrhythmia. The occurrence of ACS is mainly related to the vulnerable plaques in the coronary arteries. MicroRNA-21 (miR-21) is widely expressed in cardiovascular disease and considered as a marker of myocardial infarction, but its role in vulnerable atherosclerotic plaque of ACS is poorly studied. The cases of ACS and control group were selected in 2 years. Our results revealed that miR-21 was highly positively correlated with the maximum lipid core area, the number of diseased vessels, the number of macrophages, the number of vulnerable plaques, and negatively correlated with the thickness of fiber caps. In the high expression group, the number of coronary artery lesions, the number of vulnerable plaques, the core area of lipid pools and the number of macrophages were significantly higher than those in the low expression group and the middle expression group. But the high expression group of the thickness of the fiber cap was significantly lower than that of the low expression group and the medium expression group. These studies show that miR-21 is an important factor leading to vulnerable plaque instability in ACS, and it can be a predictor of acute adverse events in coronary heart disease.

MicroRNA‑21 increases cell viability and suppresses cellular apoptosis in non‑small cell lung cancer by regulating the PI3K/Akt signaling pathway

MicroRNA (miRNA/miR), a type of non‑coding RNA molecule, is able to inhibit the expression of target genes at multiple stagess. There are 800‑1,000 known miRNAs in the human genome, which serve important roles in cell proliferation, differentiation, apoptosis and migration. Previous studies have demonstrated that the expression of miR‑21 is upregulated in numerous types of malignant tumor, and that miR‑21 participates in the occurrence and development of tumors via complex regulatory mechanisms. The present study aimed to investigate the association between miR‑21 expression, cell viability and apoptosis in a lung cancer cell line, and to elucidate the potential mechanisms. miR‑21 or small interfering RNA against miR‑21 were transfected into A549 non‑small cell lung cancer cells. The mRNA expression of miR‑21 was confirmed. Cell viability and apoptosis were examined using MTT and flow cytometric assays, respectively. The expression of certain apoptosis‑associated proteins was detected by western blotting. The results of the present study demonstrated that miR‑21 was able to increase the proliferation of A549 cells by inhibiting cellular apoptosis. miR‑21 inhibited apoptosis by modulating the activation of the phosphatidylinositol 3‑kinase/Rac‑α serine/threonine protein kinase (Akt) pathway in A549 cells. Correspondingly, inhibition of Akt decreased the apoptosis of A549 cells in miR‑21 siRNA‑treated cells. Therefore, the results of the present study demonstrated that miR‑21 increased cell viability by inhibiting apoptosis, through regulation of Akt activation. The present study demonstrated that miR‑21 may be involved in the progression of lung cancer and may be a novel therapeutic target for the disease.

MicroRNA expression signature and the therapeutic effect of the microRNA‑21 antagomir in hypertrophic scarring

Hypertrophic scars (HS) area fibroproliferative disorder of the skin, which causes aesthetic and functional impairment. However, the molecular pathogenesis of this disease remains largely unknown and currently no efficient treatment exists. MicroRNAs (miRNAs) are involved in a variety of pathophysiological processes, however the role of miRNAs in HS development remains unclear. To investigate the miRNA expression signature of HS, microarray analysis was performed and 152 miRNAs were observed to be differentially expressed in HS tissue compared with normal skin tissues. Of the miRNAs identified, miRNA‑21 (miR‑21) was significantly increased in HS tissues and hypertrophic scar fibroblasts (HSFBs) as determined by reverse transcription‑quantitative polymerase chain reaction analysis. It was also observed that, when miR‑21 in HSFBs was blocked through use of an antagomir, the phenotype of fibrotic fibroblasts in vitro was reversed, as demonstrated by growth inhibition, induction of apoptosis and suppressed expression of fibrosis‑associated genes collagen type I α 1 chain (COL1A1), COL1A2 and fibronectin. Furthermore, miR‑21 antagomir administration significantly reduced the severity of HS formation and decreased collagen deposition in a rabbit ear HS model. The total scar area and scar elevation index were calculated and were demonstrated to be significantly decreased in the treatment group compared with control rabbits. These results indicated that the miR‑21 antagomir has a therapeutic effect on HS and suggests that targeting miRNAs may be a successful and novel therapeutic strategy in the treatment of fibrotic diseases that are difficult to treat with existing methods.

MicroRNA‑21 promotes migration and invasion of glioma cells via activation of Sox2 and β‑catenin signaling

The expression of microRNA 21 (miR-21) has been reported to be upregulated in various types of cancer, including malignant gliomas. However, its functions and mechanisms in glioma remain to be fully elucidated. The present study established miRNA‑21 overexpression and knockdown cell lines using SRY‑box 2 (Sox2) small interfering RNA (siRNA) to knockdown expression and Sox2 cDNA was cloned into pcDNA 3.1 mammalian expression vector for ectopic expression. BIO and XAV‑939 were used for β‑catenin signaling activation and knockdown, respectively. Transwell chambers were used to assay the capacity of cells to migrate. The present study determined that increased expression of miR‑21 significantly promoted the migration and invasion of glioma cells, which was accompanied by an upregulated expression of the Sox2 protein. Sox2 overexpression also promoted glioma cell migration and invasion, whereas Sox2 siRNA markedly reduced the miR‑21‑enhanced migration and invasion of glioma cells, indicating Sox2 may act as a crucial mediator of miR‑21 function. Furthermore, miR‑21 also upregulated the protein expression level of β‑catenin, whereas anti‑miR‑21 and Sox2 knockdown significantly reduced β‑catenin expression. BIO, a β‑catenin specific agonist, enhanced migration and invasion of glioma cells. XAV‑939, an inhibitor of β‑catenin signaling, markedly inhibited the migration and invasion of glioma cells, suggesting that β‑catenin may be associated with miR‑21‑ and Sox2‑induced invasion of glioma cells. Notably, BIO restored the migration and invasion potential of glioma cells, which were inhibited by Sox2 siRNA and anti‑miR‑21. These findings indicated that β‑catenin may be an important downstream mediator of miR‑21 and Sox2. Therefore, the present study identified the miR‑21/Sox2/β‑catenin signaling pathway, which may regulate the migration and invasion of human glioma cells.

Disease-linked microRNA-21 exhibits drastically reduced mRNA binding and silencing activity in healthy mouse liver

MicroRNAs (miRNAs) bind to mRNAs and fine-tune protein output by affecting mRNA stability and/or translation. miR-21 is a ubiquitous, highly abundant, and stress-responsive miRNA linked to several diseases, including cancer, fibrosis, and inflammation. Although the RNA silencing activity of miR-21 in diseased cells has been well documented, the roles of miR-21 under healthy cellular conditions are not well understood. Here, we show that pharmacological inhibition or genetic deletion of miR-21 in healthy mouse liver has little impact on regulation of canonical seed-matched mRNAs and only a limited number of genes enriched in stress response pathways. These surprisingly weak and selective regulatory effects on known and predicted target mRNAs contrast with those of other abundant liver miRNAs such as miR-122 and let-7. Moreover, miR-21 shows greatly reduced binding to polysome-associated target mRNAs compared to miR-122 and let-7. Bioinformatic analysis suggests that reduced thermodynamic stability of seed pairing and target binding may contribute to this deficiency of miR-21. Significantly, these trends are reversed in human cervical carcinoma (HeLa) cells, where miRNAs including miR-21 show enhanced target binding within polysomes and where miR-21 triggers strong degradative activity toward target mRNAs. Taken together, our results suggest that, under normal cellular conditions in liver, miR-21 activity is maintained below a threshold required for binding and silencing most of its targets. Consequently, enhanced association with polysome-associated mRNA is likely to explain in part the gain of miR-21 function often found in diseased or stressed cells.

MicroRNA-21 inhibits Serpini1, a gene with novel tumour suppressive effects in gastric cancer

BACKGROUND

A thorough understanding of gastric cancer at the molecular level is urgently needed. One prominent oncogenic microRNA, miR-21, was previously reported to be upregulated in gastric cancer.

METHODS

We performed an unbiased search for downstream messenger RNA targets of miR-21, based on miR-21 dysregulation, by using human tissue specimens and the MKN28 human gastric carcinoma cell line. Molecular techniques include microRNA microarrays, cDNA microarrays, qRT-PCR for miR and mRNA expression, transfection of MKN28 with miR-21 inhibitor or Serpini1 followed by Western blotting, cell cycle analysis by flow cytometry and luciferase reporter assay.

RESULTS

This search identified Serpini1 as a putative miR-21 target. Luciferase assays demonstrated direct interaction between miR-21 and Serpini1 3'UTR. miR-21 and Serpini1 expression levels were inversely correlated in a subgroup of gastric cancers, suggesting a regulatory mechanism that included both of these molecules. Furthermore, Serpini1 induced growth retardation of MKN28 and induced vigorous G1/S arrest suggesting its potential tumour-suppressive function in the stomach.

CONCLUSION

Taken together, these data suggest that in a subgroup of gastric cancers, miR-21 is upregulated, inducing downregulation of Serpini1, which in turn releases the G1-S transition checkpoint, with the end result being increased tumour growth.