Prognostic Role of MicroRNA-126 for Survival in Malignant Tumors: A Systematic Review and Meta-Analysis

A cellular regulator of the niche: telocyte

Interstitial cells are present in the environment of stem cells in order to increase stem cell proliferation and differentiation and they are important to increase the efficiency of their transplantation. Telocytes (TCs) play an important role both in the preservation of tissue organ integrity and in the pathophysiology of many diseases, especially cancer. They make homo- or heterocellular contacts to form the structure of 3D network through their telopodes and deliver signaling molecules via a juxtacrine and/or paracrine association by budding shed vesicles into the vascular, nervous and endocrine systems. During this interaction, along with organelles, mRNA, microRNA, long non-coding RNA, and genomic DNA are transferred. This review article not only specifies the properties of TCs and their roles in the tissue organ microenvironment but also gives information about the factors that play a role in the transport of epigenetic information by TCs.

Diagnostic implication of a circulating serum-based three-microRNA signature in hepatocellular carcinoma

Owing to the diagnostic dilemma, the prognosis of hepatocellular carcinoma (HCC) remains impoverished, contributing to the globally high mortality rate. Currently, HCC diagnosis depends on the combination of imaging modalities and the measurement of serum alpha-fetoprotein (AFP) levels. Nevertheless, these conventional modalities exhibit poor performance in detecting HCC at early stages. Thus, there is a pressing need to identify novel circulating biomarkers to promote diagnostic accuracy and surveillance. Circulating miRNAs are emerging as promising diagnostic tools in screening various cancers, including HCC. However, because of heterogenous and, at times, contradictory reports, the universality of miRNAs in clinical settings remains elusive. Consequently, we proposed to explore the diagnostic potential of ten miRNAs selected on a candidate-based approach in HCC diagnosis. The expression of ten candidate miRNAs (Let-7a, miR-15a, miR-26a, miR-124, miR-126, miR-155, miR-219, miR-221, miR-222, and miR-340) was investigated in serum and tissue of 66 subjects, including 33 HCC patients and 33 healthy controls (HC), by rt-PCR. Receiver operating characteristic curve (ROC) analysis was used to determine the diagnostic accuracy of the prospective serum miRNA panel. To anticipate the potential biological roles of a three-miRNA signature, the target genes were evaluated using the Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway. The serum and tissue expression of miRNAs (Let-7a, miR-26a, miR-124, miR-155, miR-221, miR-222, and miR-340) were differentially expressed in HCC patients (p < 0.05). The ROC analysis revealed promising diagnostic performance of Let-7a (AUC = 0.801), miR-221 (AUC = 0.786), and miR-2 (AUC = 0.758) in discriminating HCC from HC. Furthermore, in a logistic regression equation, we identified a three-miRNA panel (Let-7a, miR-221, and miR-222; AUC = 0.932) with improved diagnostic efficiency in differentiating HCC from HC. Remarkably, the combination of AFP and a three-miRNA panel offered a higher accuracy of HCC diagnosis (AUC = 0.961) than AFP alone. The functional enrichment analysis demonstrated that target genes may contribute to pathways associated with HCC and cell-cycle regulation, indicating possible crosstalk of miRNAs with HCC development. To conclude, the combined classifier of a three-miRNA panel and AFP could be indispensable circulating biomarkers for HCC diagnosis. Furthermore, targeting predicted genes may provide new therapeutic clues for the treatment of aggressive HCC.

Prognostic Value and Biological Role of miR-126 in Breast Cancer

In eukaryotic organisms such as humans, some noncoding single-stranded RNAs (ncRNAs) contribute to regulating the expression of some genes before and after the transcription process, which in turn controls a number of vital physiological processes, including cell proliferation, differentiation, invasion, angiogenesis, and embryonic development. miR-126 is one of these miRNAs expressed exclusively in endothelial cells such as capillaries and vessels involved in controlling angiogenesis. In recent years, the link between miRs such as miR-126 and the pathology of breast cancer has attracted the attention of many researchers. Numerous studies have shown that miR-126 may be able to suppress tumor tissue metastasis or to increase tumor metastasis through complex molecular mechanisms. There is ample clinical evidence that miR-126 can be used as a biomarker to predict and diagnose breast cancer due to the increased or decreased expression of certain genes in breast cancer tissue. In this review, we discuss the association between the growth and metastasis (tumorigenesis) of breast cancer and miR-126, as well as the relationship between current research advances in the prognosis, diagnosis, and treatment of breast cancer and miR-126.

Prognostic and clinicopathological value of miR-199b in cancers: a meta-analysis

Background: The prognostic value of miR-199b in cancers has not been fully clarified. Methods: All articles evaluating the prognostic value of miR-199b in tumors were included. The hazard ratio (HR), odds ratio (OR) and 95% CI were calculated to assess the relationship between miR-199b expression and survival outcomes and clinicopathological features. Results: The combined results indicated that high miR-199b expression predicted favorable overall survival (OS) compared with low miR-199b expression (HR: 0.62, 95% CI: 0.44-0.87). In addition, high miR-199b expression had a significant correlation with the prevention of lymph node metastasis (OR: 0.39, 95% CI: 0.25-0.59). Conclusion: MiR-199b can be used as an effective prognostic marker in cancers.

Role of Stress-Survival Pathways and Transcriptomic Alterations in Progression of Colorectal Cancer: A Health Disparities Perspective

Every year, more than a million individuals are diagnosed with colorectal cancer (CRC) across the world. Certain lifestyle and genetic factors are known to drive the high incidence and mortality rates in some groups of individuals. The presence of enormous amounts of reactive oxygen species is implicated for the on-set and carcinogenesis, and oxidant scavengers are thought to be important in CRC therapy. In this review, we focus on the ethnicity-based CRC disparities in the U.S., the negative effects of oxidative stress and apoptosis, and gene regulation in CRC carcinogenesis. We also highlight the use of antioxidants for CRC treatment, along with screening for certain regulatory genetic elements and oxidative stress indicators as potential biomarkers to determine the CRC risk and progression.

Prognostic significance of microRNA miR-24 in cancers: a meta-analysis

The prognostic significance of miR-24 in tumors has not been determined. Therefore, we conducted a meta-analysis to systematically assess the correlation between miR-24 and its prognostic value in cancers PubMed, EMBASE, and Web of Science databases were used to search relevant articles (up to 1 October 2020). Studies that evaluated the prognostic value of miR-24 in tumors were included. The hazard ratio (HR) and odds ratio (OR) with 95% confidence intervals (CI) were used to evaluate survival outcomes and clinical characteristics. All data analyses were implemented using STATA 12.0 software. A total of 17 studies from 15 articles involving 1705 patients were collected for the meta-analysis. The pooled analysis revealed that elevated miR-24 expression was obviously associated with poor overall survival (OS) (HR = 1.66, 95% CI: 1.20-2.31). Furthermore, we also found that elevated miR-24 expression was positively correlated with tumor size (large or small) and tumor stage (III-IV vs I-II). Elevated miR-24 expression indicates poor prognosis and may be a promising prognostic marker in different cancers. Our findings needed to be verified through further investigations. [Figure: see text].

The Dual Role of MicroRNAs in Colorectal Cancer Progression

Colorectal cancer (CRC) is responsible for one of the major cancer incidence and mortality worldwide. It is well known that MicroRNAs (miRNAs) play vital roles in maintaining the cell development and other physiological processes, as well as, the aberrant expression of numerous miRNAs involved in CRC progression. MiRNAs are a class of small, endogenous, non-coding, single-stranded RNAs that bind to the 3’-untranslated region (3′-UTR) complementary sequences of their target mRNA, resulting in mRNA degradation or inhibition of its translation as a post-transcriptional regulators. Moreover, miRNAs also can target the long non-coding RNA (lncRNA) to regulate the expression of its target genes involved in proliferation and metastasis of CRC. The functions of these dysregulated miRNAs appear to be context specific, with evidence of having a dual role in both oncogenes and tumor suppression depending on the cellular environment in which they are expressed. Therefore, the unique expression profiles of miRNAs relate to the diagnosis, prognosis, and therapeutic outcome in CRC. In this review, we focused on several oncogenic and tumor-suppressive miRNAs specific to CRC, and assess their functions to uncover the molecular mechanisms of tumor initiation and progression in CRC. These data promised that miRNAs can be used as early detection biomarkers and potential therapeutic target in CRC patients.

MicroRNA-126 affects rheumatoid arthritis synovial fibroblast proliferation and apoptosis by targeting PIK3R2 and regulating PI3K-AKT signal pathway

Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes inflammation and destruction of the joints as well as an increased risk of cardiovascular disease. RA synovial fibroblasts (RASFs) are involved in the progression of RA and release pro-inflammatory cytokines. On the other hand, microRNAs (miRs) may help control the inflammatory response of immune and non-immune cells. Therefore, our study used lentiviral expression vectors to test the effects of miR-126 overexpression on RASF proliferation and apoptosis. Luciferase experiments verified the targeting relationship between miR-126 and PIK3R2 gene. The co-transfection of anti-miR-126 and PIK3R2 siRNA to RASFs were used to identify whether PIK3R2 was directly involved in proliferation and apoptosis of miR-126-induced RASFs. Real-time polymerase chain reaction (PCR) was used to detect miR-126 and PIK3R2 expressions. MTT assay was used to detect cell proliferation. Flow cytometry was used to detect cell apoptosis and cell cycle. Western blotting was used to detect PIK3R2, PI3K, AKT and p-AKT proteins. After Lv-miR-126 infected RASFs, the relative expression of miR-126 was significantly enhanced. MiR-126 promoted RASF proliferation and inhibited apoptosis. Levels of PIK3R2 decreased while total PI3K and p-AKT levels increased in RASFs overexpressing miR-126. Co-transfection of anti-miR-126 and PIK3R2 siRNA also increased PI3K and p-AKT levels as well as RASF proliferation and reduced apoptosis, as compared to anti-miR-126 treatment alone. Finally, luciferase reporter assays showed that miR-126 targeted PIK3R2. Our data indicate that miR-126 overexpression in RASFs inhibits PIK3R2 expression and promotes proliferation while inhibiting apoptosis. This suggests inhibiting miR-126 may yield therapeutic benefits in the treatment of RA.

A plasma miRNA signature for lung cancer early detection

The early detection of lung cancer continues to be a major clinical challenge. Using whole-transcriptome next-generation sequencing to analyze lung tumor and the matched noncancerous tissues, we previously identified 54 lung cancer-associated microRNAs (miRNAs). The objective of this study was to investigate whether the miRNAs could be used as plasma biomarkers for lung cancer. We determined expressions of the lung tumor-miRNAs in plasma of a development cohort of 180 subjects by using reverse transcription PCR to develop biomarkers. The development cohort included 92 lung cancer patients and 88 cancer-free smokers. We validated the biomarkers in a validation cohort of 64 individuals comprising 34 lung cancer patients and 30 cancer-free smokers. Of the 54 miRNAs, 30 displayed a significant different expression level in plasma of the lung cancer patients vs. cancer-free controls (all P < 0.05). A plasma miRNA signature (miRs-126, 145, 210, and 205-5p) with the best prediction was developed, producing 91.5% sensitivity and 96.2% specificity for lung cancer detection. Diagnostic performance of the plasma miRNA signature had no association with stage and histological type of lung tumor, and patients' age, sex, and ethnicity (all p > 0.05). The plasma miRNA signature was reproducibly confirmed in the validation cohort. The plasma miRNA signature may provide a blood-based assay for diagnosing lung cancer at the early stage, and thereby reduce the associated mortality and cost.

Comprehensive bioinformation analysis of the miRNA of PLCE1 knockdown in esophageal squamous cell carcinoma

Phospholipase C epsilon 1 (PLCE1) has been recognized as a novel susceptibility marker for esophageal squamous cell carcinoma (ESCC). The purpose of our study is to investigate its effect on the regulation of miRNA expression so as to translating the data into a novel strategy in control of ESCC. In this study, PLCE1 siRNA and vector-only plasmid were stably transfected into Eca109 and EC9706 cells and then subjected to miRNA array analysis, and quantitative real-time PCR was applied to validate miRNA array data. Then bioinformatic analyses, such as GO and pathway software, were conducted to obtain data on these differentially expressed miRNAs-targeted genes (DEGs) and clarify their function and pathway. The results showed that 36 miRNAs were found to be differentially expressed in PLCE1 siRNA-transfected cells compared with the control cells. In particular, 28 miRNAs were upregulated while 8 miRNAs were downregulated. Gene Ontology analysis showed that the function of the DEGs included cell cycle arrest, cell-matrix adhesion, apoptosis, etc. After this, the major pathways associated with the DEGs were regulation of actin cytoskeleton, TGF-beta signaling pathway, Notch signaling pathway and so on. Taken together, these results showed that the knockdown of PLCE1 may play a vital role in the control of ESCC. Further investigation will reveal and verify the function and pathway of the DEGs for the development of novel treatment strategy for the better control of ESCC.

Identification of miRNAs as biomarkers for acquired endocrine resistance in breast cancer

Therapies targeting estrogen receptor α (ERα) including tamoxifen, a selective estrogen receptor modulator (SERM) and aromatase inhibitors (AI), e.g., letrozole, have proven successful in reducing the death rate for breast cancer patients whose initial tumors express ERα. However, about 40% of patients develop acquired resistance to these endocrine treatments. There is a critical need to develop sensitive circulating biomarkers that accurately identify signaling pathways altered in breast cancer patients resistant to endocrine therapies. Serum miRNAs have the potential to serve as biomarkers of the progression of endocrine-resistant breast cancer due to their cancer-specific expression and stability. Exosomal transfer of miRNAs has been implicated in metastasis and endocrine-resistance. This review focuses on miRNAs in breast tumors and in serum, including exosomes, from breast cancer patients that are associated with resistance to tamoxifen since it is best-studied.

Potential role of microRNA-126 in the diagnosis of cancers: A systematic review and meta-analysis

BACKGROUND

Cancer has become a major public concern all over the world and early diagnosis of cancer is of great benefit for treatment and prognosis. Several studies have investigated the association between abnormal circulating microRNA-126 (miR-126) expression and the risk of various cancers, but the results are inconsistent. Therefore, this meta-analysis was carried out to assess the potential diagnostic value of miR-126 for cancer.

METHODS

Relevant studies were searched from PubMed, Embase, and Web of Science and we calculated the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the summary receiver operator characteristic curve (AUC) to assess the diagnostic value of miR-126 for cancer detection.

RESULTS

A total of 745 cancer patients and 749 controls from 11 studies of 7 papers were included in this meta-analysis. The summary estimates revealed that the pooled sensitivity was 68% (95% confidence interval [CI]: 60-75%), the specificity was 76% (95% CI: 65-85%), the PLR was 2.87 (95% CI: 1.96-4.21), the NLR was 0.42 (95% CI: 0.35-0.52), the DOR was 7 (95% CI: 4-11), and the AUC was 0.77 (95%CI: 0.73-0.80). Moreover, the sample type, cancer type, sample size, and quality score might be sources of heterogeneity.

CONCLUSION

This systematic review and meta-analysis suggests that miR-126 has great potential to be a noninvasive biomarker in the diagnosis of cancer. However, more well-designed studies with larger sample size on the diagnostic value of miR-126 for cancer are needed in the future.

Hepatic miR-126 is a potential plasma biomarker for detection of hepatitis B virus infected hepatocellular carcinoma

Controversies about the origin of circulating miRNAs have encouraged us to identify organ specific circulating miRNAs as disease biomarkers. To identify liver-specific miRNAs for hepatocellular carcinoma (HCC), global expression profiling of miRNAs in liver tissue of HBV-HCC and HBV-control with no or mild fibrosis was evaluated. A total of 40 differentially expressed miRNAs were identified in HCC. Among ten highly altered miRNAs, six miRNAs were successfully validated in tissues, whereas only two miRNAs, miR-126 and miR-142-3p showed increased expression in plasma of HBV-HCC compared to HBV-non-HCC patients. Subsequently, ROC curve analysis revealed that neither miR-126 nor miR-142-3p performed better than AFP in discriminating HCC from non-HCC while combination of each with AFP showed significantly higher efficiency rather than AFP alone (AUC: 0.922, 0.908 vs. 0.88; sensitivity: 0.84, 0.86 vs. 0.82 and specificity: 0.92, 0.94 vs. 0.86 respectively). Interestingly, triple combination of markers (miR-126 + miR-142-3p + AFP) showed no additive effect on efficiency (AUC: 0.925) over the dual combination. Again, the expression of only miR-126 was noticed significantly higher in HBV-HCC patients with low-AFP [<250 ng/ml] compared to either non-HCC or liver cirrhosis (AUC: 0.77, 0.64, respectively). Furthermore, no alteration in expression of mir-126 in HCV-HCC or non-viral-HCC revealed that miR-126 + AFP might be specific to HBV-HCC. To understand the physiological role of these two miRNAs in hepato-carcinogenesis, target genes related to cancer pathways (APAF1, APC2, CDKN2A, IRS1, CRKL, LIFR, EGR2) were verified. Thus, combination of circulating miR-126 + AFP is a promising noninvasive diagnostic biomarker for HBV-HCC and may be useful in the management of HCC patients.