Potential role of microRNA-126 in the diagnosis of cancers: 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.

MicroRNA‑126 expression in the peripheral white blood cells of patients with breast and ovarian cancer is a potential biomarker for the early prediction of cancer risk in the carriers of methylated BRCA1

Constitutive breast cancer type 1 gene (BRCA1) promoter methylation is associated with increased cancer risk, but its role in cancer-free (CF) female carriers is incompletely understood. MicroRNA (miR) is modulated during early tumorigenesis. The present study assessed the modulation of miR-126 expression in the peripheral white blood cells (WBC) of patients with breast cancer (BC) and ovarian cancer (OC) as a biomarker of cancer risk in BRCA1 methylation carriers. A total of 1,114 female subjects [502 patients with BC, 187 patients with OC and 425 CF volunteers] were involved. Screening for BRCA1 promoter methylation in WBC was performed using the methylation–specific polymerase chain reaction (PCR) assay, BRCA1 mRNA was analyzed using a reverse transcription-quantitative PCR assay and miR-126 expression was analyzed using a stem-loop RT-qPCR assay. WBC BRCA1 promoter methylation status was significantly associated with OC (P=0.0266), early-onset BC (P=0.0003) and triple-negative BC (P=0.0066). Notably, 9.4% of the CF group exhibited WBC BRCA1 promoter methylation. In addition, high levels of miR-126 in WBCs were detected in all three groups. The increased level of miR-126 was significantly associated with a lower risk of distant metastasis (P=0.045) in BC, but a higher risk of disease progression and death (P=0.0029) in OC. There was a positive correlation between BRCA1 mRNA and miR-126 levels in the WBCs of all three groups, regardless of BRCA1 promoter methylation status. Notably, circulating miR-126 level was decreased in the BC and OC groups, but not in the CF group. Together, these results suggest the likely involvement of miR-126 in the constitutional methylation of BRCA1 promoter-related malignancies. Therefore, miR-126 may be a candidate biomarker for the early prediction of BC and OC risk in CF BRCA1 methylation carriers.

Knockdown of circPVT1 inhibits progression of papillary thyroid carcinoma by sponging miR-126

Background: Papillary thyroid carcinoma (PTC) is the most common thyroid cancer. Recent studies have reported that circular RNAs (circRNAs) play essential roles in human cancers, including PTC. However, the roles of circRNA plasmacytoma variant translocation 1 (PVT1) in PTC progression and its potential mechanism remain largely unknown. Methods: The expressions of circPVT1 and microRNA-126 (miR-126) were measured in PTC tissues and cells by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability, apoptosis, migration and invasion were detected in PTC cells by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), flow cytometry, Western blot or trans-well assays, respectively. The interaction between circPVT1 and miR-126 was explored by bioinformatics analysis, luciferase activity assay and RNA immunoprecipitation. A mouse xenograft model was established to investigate the role of circPVT1 in PTC progression in vivo. Results: High expression of circPVT1 was shown in PTC tissues and cells and was associated with poor outcomes of patients. Knockdown of circPVT1 suppressed viability, migration and invasion but induced apoptosis in PTC cells. miR-126 was bound to circPVT1 and reduced in PTC tissues and cells. Moreover, inhibition of miR-126 reversed the regulatory effect of the circPVT1 interference on viability, apoptosis, migration and invasion in PTC cells. Besides, circPVT1 knockdown attenuated tumor growth via up-regulating miR-126 in vivo. Conclusion: CircPVT1 knockdown inhibited PTC progression by sponging miR-126. This may indicate circPVT1 as a novel target for treatment of PTC.

Papillary thyroid carcinoma (PTC) is the most common thyroid cancer. Recent studies have reported that circular RNAs (circRNAs) play essential roles in human cancers, including PTC.

Co-exposure to metals and polycyclic aromatic hydrocarbons, microRNA expression, and early health damage in coke oven workers

BACKGROUND

All humans are now co-exposed to multiple toxic chemicals, among which metals and polycyclic aromatic hydrocarbons (PAHs) are of special concern as they are often present at high levels in various human environments. They can also induce similar early health damage, such as genetic damage, oxidative stress, and heart rate variability (HRV). Exposure to metals, PAHs, and their combined pollutants can alter microRNA (miRNA) expression patterns.

OBJECTIVES

To explore the associations of metal-PAH co-exposure with miRNA expression, and of the associated miRNAs with early health damage.

METHODS

We enrolled 360 healthy male coke oven workers and quantified their exposure levels of metals and PAHs by urinary metals, urinary monohydroxy-PAHs (OH-PAHs), and plasma benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydotetrol-albumin (BPDE-Alb) adducts, respectively. We selected and measured ten miRNAs: let-7b-5p, miR-126-3p, miR-142-5p, miR-150-5p, miR-16-5p, miR-24-3p, miR-27a-3p, miR-28-5p, miR-320b, and miR-451a. For miRNAs influenced by the effect modification of metals or PAHs and/or metal-PAH interactions, we further evaluated their associations with biomarkers for genetic damage, oxidative stress, and HRV.

RESULTS

After adjusting for PAHs and other metals, miRNA expression was found to be negatively associated with aluminum, antimony, lead, and titanium, and positively associated with molybdenum and tin (p < 0.05). Antimony showed modifying effects on the PAH-miRNA associations, while OH-PAHs and BPDE-Alb adducts modified the associations of metals with miRNAs (p for modifying effect < 0.05). Furthermore, miRNA expression was influenced by the antagonistic interactions between antimony and OH-PAHs, and by the synergistical interactions between metals and BPDE-Alb adducts (p_interaction < 0.05). Let-7b-5p, miR-126-3p, miR-16-5p, and miR-320b were additionally found to be associated with increased genetic damage in the present study [false discovery rate (FDR)-adjusted p < 0.05].

CONCLUSIONS

Associations of metal-PAH co-exposure with miRNA expression, and of associated miRNAs with early health damage, suggested potential mechanistic connections between the complex metal-PAH interactions and their deleterious effects that are worthy of further investigation.

Modulating secreted components of tumor microenvironment: A masterstroke in tumor therapeutics

The microenvironment in which cancer resides plays an important role in regulating cancer survival, progression, malignancy and drug resistance. Tumor microenvironment (TME) consists of heterogeneous number and types of cellular and non-cellular components that vary in relation to tumor phenotype and genotype. In recent, non-cellular secreted components of microenvironmental heterogeneity have been suggested to contain various growth factors, cytokines, RNA, DNA, metabolites, structural matrix and matricellular proteins. These non-cellular components have been indicated to orchestrate numerous ways to support cancer survival and progression by providing metabolites, energy, growth signals, evading immune surveillance, drug resistance environment, metastatic and angiogenesis cues. Thus, switching action from pro-cancer to anti-cancer activities of these secreted components of TME has been considered as a new avenue in cancer therapeutics and drug resistance. In this report, we summarize the recent pre-clinical and clinical evidences to emphasize the importance of non-cellular components of TME in achieving precision therapeutics and biomarker study.

Secretory microRNAs as biomarkers of cancer

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression predominantly by inhibiting transcription and/or promoting degradation of target mRNAs also in addition to being involved in non-canonical mechanisms regulating transcription, translation and cell signaling processes. Extracellular secretory miRNAs, either in complex with specific proteins or encapsulated in microvesicles called exosomes, are transported between cells as means of intercellular communication. Secretory miRNAs in circulation remain functional after delivery to recipient cells, regulating target genes and their corresponding signaling pathways. Cancer cell secreted miRNA-mediated intercellular communication affects physiological processes associated with the disease, such as, angiogenesis, metabolic reprogramming, immune modulation, metastasis, and chemo-resistance. Given the stability of miRNAs in body fluids and their well-documented roles in deregulating cancer-relevant genetic pathways, there is considerable interest in developing secretory miRNAs as liquid biopsy biomarkers for detection, diagnosis and prognostication of cancer. In this review, we discuss salient features of miRNA biogenesis, secretion and function in cancer as well as the current state of secretory miRNA isolation and profiling methods. Furthermore, we discuss the challenges and opportunities of secretory miRNA biomarker assay development, which need to be addressed for clinical applications.

The prognostic value of miR-126 expression in non-small-cell lung cancer: a meta-analysis

OBJECTIVE

Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related death. Growing evidence from recent studies have shown indicated that microRNA-126 (miR-126) played an important role in the progression of NSCLC. However, the potential value of miR-126 expression in prognosis of NSCLC remains to be fully elucidated. Here, we carried out a meta-analysis to assess the potential prognostic value of miR-126 for NSCLC.

METHODS

PubMed, Embase, the Cochrane library, Web of Science, CNKI and WanFang database, as well as the reference of included studies, were searched to recognize pertinent studies until April 30, 2017. New castle-Ottawa scale was used to evaluate the quality of studies. Pooled hazard ratio (HR) with 95% confidence interval (CI) for overall survival (OS) was extracted by using a fixed-effects or a random-effects model on the basis of heterogeneity. Publication bias was evaluated by using Begg's tests.

RESULTS

We identified four eligible trials involving 666 non-small-cell lung cancer patients in this meta-analysis. The results indicated that a high level of miR-126 played a favorable role in the overall survival (HR 0.73, 95% CI 0.61-0.86, fixed-effects model). There was no bias existed in this study.

CONCLUSIONS

Our study showed that high expression level of miR-126 was a promising positive factor for OS for non-small cell lung cancer patients, and miR-126 might be a potential target for non-small-cell lung cancer therapy in the future.

Comparison of microRNA expression profiles in K562-cells-derived microvesicles and parental cells, and analysis of their roles in leukemia

Microvesicles (MVs) are 30-1,000-nm extracellular vesicles that are released from a multitude of cell types and perform diverse cellular functions, including intercellular communication, antigen presentation, and transfer of proteins, messenger RNA and microRNA (also known as miR). MicroRNAs have been demonstrated to be aberrantly expressed in leukemia, and the overall microRNA expression profile may differentiate normal blood cells vs. leukemia cells. MVs containing microRNAs may enable intercellular cross-talk in vivo. This prompted us to investigate specific variations of microRNA expression patterns in MVs derived from leukemia cells. The present study examined the microRNA expression profile of MVs from chronic myeloid leukemia K562 cells and that of MVs from normal human volunteers' peripheral blood cells. The potential targets of the differentially expressed microRNAs were predicted using computational searches. Bioinformatic analyses of the predicted target genes were performed for further evaluation. The present study analyzed microRNAs of MVs derived from leukemia and normal cells, and characterized specific microRNAs expression. The results revealed that MVs derived from K562 cells expressed 181 microRNAs of the 888 microRNAs assessed. Further analysis revealed that 16 microRNAs were downregulated, while 7 were upregulated in these MVs. In addition, significant differences in microRNA expression profiles between MVs derived from K562 cells and K562 cells were identified. The present results revealed that 77 and 122 microRNAs were only expressed in MVs derived from K562 cells and in K562 cells, respectively. There were 104 microRNAs co-expressed in MVs derived from K562 cells and in K562 cells. Target gene-related pathway analyses demonstrated that the majority of the dysregulated microRNAs were involved in pathways associated with leukemia, particularly the mitogen-activated protein kinase (MAPK) and the p53 signaling pathways. By further conducting microRNA gene network analysis, the present study revealed that the miR-15a/b, miR-16, miR-17 and miR-30 families were likely to play a role in the regulation of the MAPK signaling pathway. Since K562 cells presented the t(9;22) translocation, the current study further examined the predicted function of 12 microRNAs located in chromosomes 9 [Homo sapiens (hsa)-let-7a, hsa-let-7f, miR-126, miR-126*, miR-23b, miR-24, miR-27b and miR-7] and 22 (hsa-let-7b, miR-1249, miR-130b and miR-185), which were expressed both in MVs derived from K562 cells and in K562 cells. The present study identified microRNAs of MVs from leukemia and normal cells, and characterized the expression of specific microRNAs. The current study is also the first to identify and characterize distinct microRNA expression between MVs derived from K562 cells and K562 cells. These findings highlight that a number of microRNAs from leukemia-derived MVs may contribute to the development of hematopoietic malignancies. Further investigation may reveal the function of these differentially expressed microRNAs and may provide potential targets for novel therapeutic strategies.