miRNA therapy targeting cancer stem cells: a new paradigm for cancer treatment and prevention of tumor recurrence

Unlocking melanoma Suppression: Insights from Plasma-Induced potent miRNAs through PI3K-AKT-ZEB1 axis

INTRODUCTION

Melanoma is a rare but highly malignant form of skin cancer. Although recent targeted and immune-based therapies have improved survival rates by 10-15%, effective melanoma treatment remains challenging. Therefore, novel, combinatorial therapy options such as non-thermal atmospheric pressure plasma (NTP) are being investigated to inhibit and prevent chemoresistance. Although several studies have reported the apoptotic and inhibitory effects of reactive oxygen species produced by NTP in the context of melanoma, the intricate molecular network that determines the role of microRNAs (miRNAs) in regulating NTP-mediated cell death remains unexplored.

OBJECTIVES

This study aimed to explore the molecular mechanisms and miRNA networks regulated by NTP-induced oxidative stress in melanoma cells.

METHODS

Melanoma cells were exposed to NTP and then subjected to high-throughput miRNA sequencing to identify NTP-regulated miRNAs. Various biological processes and underlying molecular mechanisms were assessed using Alamar Blue, propidium iodide (PI) uptake, cell migration, and clonogenic assays followed by qRT-PCR and flow cytometry.

RESULTS

NTP exposure for 3 min was sufficient to modulate the expression of several miRNAs, inhibiting cell growth. Persistent NTP exposure for 5 min increased differential miRNA regulation, PI uptake, and the expression of genes involved in cell cycle arrest and death. qPCR confirmed that miR-200b-3p and miR-215-5p upregulation contributed to decreased cell viability and migration. Mechanistically, inhibiting miR-200b-3p and miR-215-5p in SK-2 cells enhancedZEB1, PI3K, and AKT expression, increasing cell proliferation and viability.

CONCLUSION

This study demonstrated that NTP exposure for 5 min results in the differential regulation of miRNAs related to the PI3K-AKT-ZEB1 axis and cell cycle dysregulation to facilitate melanoma suppression.

miR-26a-5p Suppresses Wnt/β-Catenin Signaling Pathway by Inhibiting DNMT3A-Mediated SFRP1 Methylation and Inhibits Cancer Stem Cell-Like Properties of NSCLC

Background

Lung cancer is a malignant cancer which results in the most cancer incidence and mortality worldwide. There is increasing evidence that the pattern of DNA methylation affects tumorigenesis and progression. However, the molecules and mechanisms regulating DNA methylation remain unclear.

Methods

The expression of miR-26a-5p in NSCLC cell lines was detected by qPCR and verified in NSCLC tissues from TCGA using Limma R package. CCK-8 assay, plate clone formation assay, flow cytometry, and sphere formation assay were used to detect the cell proliferation, colony formation, cell cycle, and cancer stem cell- (CSC-) like property in NSCLC cell lines. The immunoblotting was used to detect the protein levels of DNMT3A, SFRP1, and Ki67. Global DNA methylation levels and DNA methylation levels of SFRP1 promoter were examined using ELISA and MSP-PCR assay, respectively. The distribution of β-catenin was examined using immunofluorescence (IF). Besides, xenograft mouse model was used to investigate the antitumor effects of miR-26a-5p in vivo. The pathology and protein levels were, respectively, detected by hematoxylin and eosin (H&E) and immunocytochemistry (IHC).

Results

The expression of miR-26a-5p was downregulated in the tumor tissues comparted to adjacent normal tissues as well as NSCLC cell lines compared to normal lung epithelial cell (BEAS2B). The overexpression of miR-26a-5p inhibited cell proliferation, colony formation, CSC-like property, and arrested cell cycle at G1 phase. DNMT3A was a target of miR-26a-5p and upregulated DNA methylation on SFRP1 promoter. Mechanistically, miR-26a-5p repressed cell proliferation, colony formation, CSC-like property, and arrested cell cycle at G1 phase by binding DNMT3A to reduce DNA methylation levels of SFRP1 then upregulated SFRP1 expression. Moreover, miR-26a-5p exerted antitumor effects in vivo.

Conclusion

Our results revealed that miR-26a-5p acted as a tumor suppressor through targeting DNMT3A to upregulate SFRP1 via reducing DNMT3A-dependent DNA methylation.

The Circ-CYP24A1-miR-224-PRLR Axis Impairs Cell Proliferation and Apoptosis in Recurrent Miscarriage

Aim

Recurrent miscarriage (RM) is associated with numerous clinical factors. However, some RM occurred without specific factors. It has been revealed that some molecules such as hormones, miRNAs, and transcription factors are involved in RM by regulating proliferation, apoptosis, etc. However, the mechanism of RM has yet to be identified clearly. Circular RNAs (circRNAs) are a class of endogenous non-coding RNAs that often act as sponges for miRNAs or binds to proteins involved in biological processes. However, the functional role of circRNAs in the uterine decidua of patients with early RM is still unclear. In this study, we aimed to investigate the mechanisms of circ-CYP24A1 in RM.

Methods

The Dual-Luciferase Activity Assay was designed to analyze the bonding between circ-CYP24A1 and miR-224, and miR-224 and prolactin receptor (PRLR) mRNA 3′UTR. In situ hybridization (ISH) and immunohistochemistry (IHC) were used to observe the expression of circ-CYP24A1 and PRLR in the decidua. Rescue experiments were performed to investigate the regulating effects of circ-CYP24A1, miR-224, and PRLR. Western blotting was conducted to test the expression level of PRLR. The proliferation and apoptosis-related markers in Ishikawa cells were analyzed using CCK8, immunofluorescence staining, and the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay.

Results

In this study, based on the microarray analysis data, we identified a high level of circ-CYP24A1 and PRLR in the decidua of patients with early RM. Based on the bioinformatics prediction, the binding relationship between circ-CYP24A1 and miR-224, as well as miR-224 and PRLR, were verified. Functional experiments demonstrated that circ-CYP24A1 regulated proliferation and apoptosis by binding to and inhibiting miR-224, resulting in increased PRLR expression. Taken together, this study provides new insights into the mechanism of RM.

Conclusion

In this study, we found that circ-CYP24A1 plays a role in RM by impairing the balance of cell proliferation and apoptosis by sponging miR-224, thereby regulating PRLR.

A novel mechanism of the lncRNA PTTG3P/miR-142-5p/JAG1 axis modulating tongue cancer cell phenotypes through the Notch1 signaling

Tongue cancer is the most prevalent type of oral cancer. Our previous study revealed that JAG1 exerted an oncogenic effect on tongue carcinoma through the JAG1/Notch pathway. In this study, a lncRNA PTTG3P which was upregulated in tongue cancer, was found to be positively correlated with JAG1. In CAL-27 and SCC4 cells, PTTG3P silencing significantly decreased JAG1 proteins and the ability of tongue tumor cells to proliferate and migrate. PTTG3P overexpression exhibited the opposite effect on CAL-27 and SCC4 cells. PPTG3P directly bound miR-142-5p, and miR-142-5p directly bound 3'UTR of JAG1 and inhibited the expression levels of JAG1. As opposed to PTTG3P silencing, miR-142-5p inhibition increased JAG1 protein levels and tongue cancer cell proliferation and migration; moreover, miR-142-5p inhibition substantially reversed the effects of PTTG3P silencing. Finally, the PPTG3P/miR-142-5p axis regulated the level of NICD, Notch downstream c-myc, and cyclin D1, as well as EMT markers Snail, Twist, and Vimentin. In conclusion, the PTTG3P/miR-142-5p axis modulates tongue cancer aggressiveness through JAG1, potentially through a JAG1/Notch signaling pathway.

Selectively targeting cancer stem cells: Current and novel therapeutic strategies and approaches in the effective eradication of cancer

Cancer stem cells (CSCs) are a subgroup of cells in malignant cancers, which possess self-renewal capacity, tumor-initiating capability, and pluripotency, as well as being responsible for tumor maintenance, metastasis, relapse, and chemoresistance. The treatment modalities previously established for cancer included surgery, chemotherapy, and radiotherapy. The majority of tumor cells of non-CSCs could be eradicated using conventional chemotherapy and radiotherapy. Therefore, novel and promising therapeutic strategies that selectively target CSCs are of great importance. In this review, we described different therapeutic strategies such as immunotherapy, metabolism-based therapeutic strategies, and additional potential therapeutic approaches (targeting microRNAs [miRNAs], histone deacetylase, and DNA methyl transferase) against CSCs. Taken together, due to the inefficiency of anticancer single therapies, targeting CSCs through their metabolism and using immunotherapy and miRNAs besides classical chemo- and radiotherapy may exert better therapeutic effects.

Current understanding of epigenetics mechanism as a novel target in reducing cancer stem cells resistance

At present, after extensive studies in the field of cancer, cancer stem cells (CSCs) have been proposed as a major factor in tumor initiation, progression, metastasis, and recurrence. CSCs are a subpopulation of bulk tumors, with stem cell-like properties and tumorigenic capabilities, having the abilities of self-renewal and differentiation, thereby being able to generate heterogeneous lineages of cancer cells and lead to resistance toward anti-tumor treatments. Highly resistant to conventional chemo- and radiotherapy, CSCs have heterogeneity and can migrate to different organs and metastasize. Recent studies have demonstrated that the population of CSCs and the progression of cancer are increased by the deregulation of different epigenetic pathways having effects on gene expression patterns and key pathways connected with cell proliferation and survival. Further, epigenetic modifications (DNA methylation, histone modifications, and RNA methylations) have been revealed to be key drivers in the formation and maintenance of CSCs. Hence, identifying CSCs and targeting epigenetic pathways therein can offer new insights into the treatment of cancer. In the present review, recent studies are addressed in terms of the characteristics of CSCs, the resistance thereof, and the factors influencing the development thereof, with an emphasis on different types of epigenetic changes in genes and main signaling pathways involved therein. Finally, targeted therapy for CSCs by epigenetic drugs is referred to, which is a new approach in overcoming resistance and recurrence of cancer.

Cancer Stem Cell Transcriptome Profiling Reveals Seed Genes of Tumorigenesis: New Avenues for Cancer Precision Medicine

Cancer stem-like cells (CSCs) possess the ability to self-renew and differentiate, and they are among the major factors driving tumorigenesis, metastasis, and resistance to chemotherapy. Therefore, it is critical to understand the molecular substrates of CSC biology so as to discover novel molecular biosignatures that distinguish CSCs and tumor cells. Here, we report new findings and insights by employing four transcriptome datasets associated with CSCs, with CSC and tumor samples from breast, lung, oral, and ovarian tissues. The CSC samples were analyzed to identify differentially expressed genes between CSC and tumor phenotypes. Through comparative profiling of expression levels in different cancer types, we identified 17 "seed genes" that showed a mutual differential expression pattern. We showed that these seed genes were strongly associated with cancer-associated signaling pathways and biological processes, the immune system, and the key cancer hallmarks. Further, the seed genes presented significant changes in their expression profiles in different cancer types and diverse mutation rates, and they also demonstrated high potential as diagnostic and prognostic biomarkers in various cancers. We report a number of seed genes that represent significant potential as "systems biomarkers" for understanding the pathobiology of tumorigenesis. Seed genes offer a new innovation avenue for potential applications toward cancer precision medicine in a broad range of cancers in oncology in the future.

Effect of c-fos gene silence on PM2.5-induced miRNA alteration in human bronchial epithelial cells

Human bronchial epithelial (HBE) cells and c-fos-silenced HBE cells were first exposed to fine particulate matter (PM_2.5) and the resulting miRNA sequenced. Thereafter, a weighted gene co-expression network analysis was performed using Cytoscape software to visualize the interactions between identified hub miRNAs and their target genes. Nine differentially expressed miRNAs in hub miRNAs were identified in the different treatment groups, of which miR-25-3p, miR-215-5p, and miR-145-5p were selected for further study. Following qPCR validation, both miR-25-3p and miR-215-5p were found to be significantly up-regulated whilst, miR-145-5p was significantly down-regulated (p < 0.05) in the PM_2.5 group. Furthermore, miR-25-3p and miR-145-5p were also significantly down-regulated in the untreated group of c-fos silenced HBE cells. However, miR-215-5p was significantly down-regulated in both the untreated and PM_2.5-treated groups of c-fos silenced HBE cells. Subsequent analysis of their target genes also illustrated differential gene expression when comparing the treatment groups of the two cell types. The present data indicated that the c-fos gene has an important effect on the miRNA expression profiles and the related signaling pathways in PM_2.5-treated HBE cells. Therefore, each of miR-25-3p, miR-145-5p, and miR-215-5p may potentially provide future research information for additional exploration of a PM_2.5-induced carcinogenesis mechanism.

Cancer Stem Cells Are Possible Key Players in Regulating Anti-Tumor Immune Responses: The Role of Immunomodulating Molecules and MicroRNAs

Simple Summary

This review provides a critical overview of the state of the art of the characterization of the immunological profile of a rare component of the tumors, denominated cancer stem cells (CSCs) or cancer initiating cells (CICs). These cells are endowed with the ability to form and propagate tumors and resistance to therapies, including the most innovative approaches. These investigations contribute to understanding the mechanisms regulating the interaction of CSCs/CICs with the immune system and identifying novel therapeutic approaches to render these cells visible and susceptible to immune responses.

Abstract

Cancer cells endowed with stemness properties and representing a rare population of cells within malignant lesions have been isolated from tumors with different histological origins. These cells, denominated as cancer stem cells (CSCs) or cancer initiating cells (CICs), are responsible for tumor initiation, progression and resistance to therapies, including immunotherapy. The dynamic crosstalk of CSCs/CICs with the tumor microenvironment orchestrates their fate and plasticity as well as their immunogenicity. CSCs/CICs, as observed in multiple studies, display either the aberrant expression of immunomodulatory molecules or suboptimal levels of molecules involved in antigen processing and presentation, leading to immune evasion. MicroRNAs (miRNAs) that can regulate either stemness properties or their immunological profile, with in some cases dual functions, can provide insights into these mechanisms and possible interventions to develop novel therapeutic strategies targeting CSCs/CICs and reverting their immunogenicity. In this review, we provide an overview of the immunoregulatory features of CSCs/CICs including miRNA profiles involved in the regulation of the interplay between stemness and immunological properties.

Circular RNA Foxo3: A Promising Cancer-Associated Biomarker

Circular RNAs (circRNAs) are a class of novel non-coding RNAs (ncRNAs). Emerging evidence demonstrates that circRNAs play crucial roles in many biological processes by regulating linear RNA transcription, downstream gene expression and protein or peptide translation. Meanwhile, recent studies have suggested that circRNAs have the potential to be oncogenic or anti-oncogenic and play vital regulatory roles in the initiation and progression of tumors. Circular RNA Forkhead box O3 (circ-Foxo3, hsa_circ_0006404) is encoded by the human FOXO3 gene and is one of the most studied circular RNAs acting as a sponge for potential microRNAs (miRNAs) (Du et al., 2016). Previous studies have reported that circ-Foxo3 is involved in the development and tumorigenesis of a variety of cancers (bladder, gastric, acute lymphocytic leukemia, glioma, etc.). In this review, we summarize the current studies concerning circ-Foxo3 deregulation and the correlative mechanism in various human cancers. We also point out the potential clinical applications of this circRNA as a biomarker for cancer diagnosis and prognosis.

MicroRNA-130b functions as an oncogene and is a predictive marker of poor prognosis in lung adenocarcinoma

Lung cancer is an aggressive disease and the leading cause of cancer-related deaths worldwide. In the past several decades, the incidence of adenocarcinoma has significantly increased, and accounts for ~40% of all lung cancer cases. In the present study, we investigated the clinicopathologic significance of microRNA-130b (miR-130b) in lung adenocarcinoma and analyzed its cancer-specific functions. RNA was extracted from formalin-fixed paraffin-embedded specimens of 146 lung adenocarcinoma cases, and miR-130b expression was analyzed using quantitative real-time polymerase chain reaction. NCI-H1650 cells were transfected with miR-130b mimic and inhibitor to determine its effects on tumor cell proliferation, migration, and invasion. The expression of miR-130b in lung adenocarcinoma tissues was classified into two groups according to the median value. High expression of miR-130b was associated with higher histological grade, advanced pathologic T stage, lymph node metastasis, and lymphovascular invasion. Moreover, survival analysis showed that high miR-130b expression was significantly associated with unfavorable prognosis. In addition, miR-130b upregulation promoted cell migration and invasion, while its downregulation resulted in decreased cell proliferation, migration, and wound healing in in vitro experiments. In conclusion, these findings suggest that miR-130b promotes tumor progression and serves as a biomarker of poor prognosis for patients with lung adenocarcinoma. Hence, targeting miR-130b may serve as a potential therapeutic strategy for lung cancer.

Soybean-derived miRNAs specifically inhibit proliferation and stimulate apoptosis of human colonic Caco-2 cancer cells but not normal mucosal cells in culture

MicroRNAs (miRNAs) are important regulators of gene expression in eukaryotes. Studies have shown that plant-derived miRNAs can be absorbed through diets and regulate gene expression in mammals. Although soybean-derived miRNAs have been reported, their biological functions are still unclear. In this study, we found that soybean-derived small RNAs (sRNAs) significantly inhibited the proliferation and stimulated the apoptosis of Caco-2 cells. Bioinformatics analysis indicated that the target gene set of soybean miRNAs was extensively enriched in cancer pathways. Besides, we obtained 8 target genes, including Transcription factor 7 (TCF7), associated with colon cancer through prediction. Further studies showed that gma-miR159a inhibited the proliferation of Caco-2 cells and played an important role in the inhibitory effect of sRNAs by inhibiting TCF7 protein, which are upregulated in colon cancer cells but not normal mucosal cells in culture. These findings provide a novel molecular mechanism of soybean-derived miRNAs for potential application in tumor prevention.

Expression and diagnostic value of miR-34c and miR-141 in serum of patients with colon cancer

Expression of miR-34c and miR-141 in serum of colon cancer patients and their association with clinicopathological features and diagnostic value for colon cancer were investigated. A total of 64 patients with colon cancer admitted to Hubei Cancer Hospital from January 2016 to March 2018 were included in the experimental group, and 64 healthy subjects undergoing physical examination during the same period were the control group. The expression of miR-34c and miR-141 in serum of patients in the two groups were detected by RT-qPCR, and the association of miR-34c and miR-141 with the clinicopathological characteristics of colon cancer patients was analyzed. The receiver operating characteristic (ROC) curve was used to assess the diagnostic efficiency of miR-34c and miR-141 in colon cancer. The expression of miR-141 in serum of patients in the experimental group was significantly higher than that in the control group (P<0.05). Expression of miR-34c in serum of patients in the experimental group was significantly lower than that in the control group (P<0.05) and the expression of miR-34c and miR-141 in serum of the experimental group were associated with tumor diameter, clinical stage, degree of differentiation and lymph node metastasis (P<0.05). AUC of serum miR-34c in the diagnosis of colon cancer was 0.857 (95% CI: 0.795-0.919), with the cut-off value of 0.800, the diagnostic sensitivity of 84.38%, and the specificity of 68.75% and AUC of serum miR-141 in the diagnosis of colon cancer was 0.876 (95% CI: 0.810-0.941), with the cut-off value of 0.282, the diagnostic sensitivity of 70.31%, and the specificity of 96.88%. The ROC curve for the diagnosis of colon cancer was further plotted in combination with serum miR-34c and miR-141. AUC of the two combined for the diagnosis of colon cancer was 0.929 (95% CI: 0.884-0.974), with the cut-off value of 0.566, the diagnostic sensitivity of 84.38%, and the specificity of 93.75%. In conclusion, miR-34c and miR-141 might be involved in the occurrence and progression of colon cancer and could be used as biological indicators for early diagnosis of colon cancer.

Development of Antibody-Oligonucleotide Complexes for Targeting Exosomal MicroRNA

MicroRNAs in exosomes (exosomal miRNAs) are considered as significant targets for cancer therapy. Anti-miR oligonucleotides are often used for the functional inhibition of miRNAs; however, there are no studies regarding the regulation of exosomal miRNA functions. In this study, we attempted to develop a novel drug delivery system using anti-exosome antibody-anti-miR oligonucleotide complexes (ExomiR-Tracker) to hijack exosomes to carry anti-miR oligonucleotides inside exosome-recipient cells. We found that ExomiR-Tracker bound to the exosomes, and then the complexes were introduced into the recipient cells. We also found that anti-miR oligonucleotides introduced into the recipient cells can exhibit inhibitory effects on exosomal miRNA functions in vitro and in vivo. We believe that our strategy would be a promising one for targeting exosomal miRNAs.

Downregulation of MicroRNA-551b Correlates With Dissemination of Human Oral Squamous Cell Carcinoma

PURPOSE

Altered expression of microRNAs contributes to invasion and metastasis of many human cancers; however, the importance of microRNAs in head and neck cancers remains to be elucidated. In this study, we examined whether altered microRNA (miR)-551b expression correlated with invasive phenotypes of human oral squamous cell carcinoma (OSCC) in vivo and in vitro.

MATERIALS AND METHODS

Real-time polymerase chain reaction was used to detect the expression level of miR-551b in 71 OSCC tissues with lymph node metastasis and 50 nonmetastatic OSCC tissues. We also constructed miR-551b mimic-transfected cell lines HN4 and HN12. The effects of overexpressing miR-551b on the proliferation, migration, and invasion of OSCC cells were examined using Cell Counting Kit 8 (Dojindo, Kumamoto, Japan), plate clone formation, wound healing, and Transwell invasion experiments (Corning, Corning, NY). The association between clinical pathologic parameters and the expression level of miR-551b was analyzed using Kaplan-Meier survival analysis.

RESULTS

The expression of miR-551b measured 0.33 ± 0.11 in the 71 OSCC tissues with lymph node metastasis versus 0.54 ± 0.06 in the 50 tissues with non-lymph node metastasis (P = .021). Regarding OSCC patients, the expression of miR-551b negatively correlated with patients' overall survival (P = .035). The ectopic expression of miR-551b inhibited the invasion and migration of OSCC cells.

CONCLUSIONS

This is the first report showing that reduced miR-551b expression may be an event leading to OSCC invasion and metastasis.

miR-296-5p suppresses stem cell potency of hepatocellular carcinoma cells via regulating Brg1/Sall4 axis

Epithelial-mesenchymal transition (EMT), a pivotal event during cancer progression such as relapse and metastasis, is positively correlated with the stemness potency of tumor cells. Our previous study showed that miR-296-5p attenuated EMT program of hepatocellular carcinoma cells (HCC) through NRG1/ERBB2/ERBB3 signaling. In the present study, we uncovered that miR-296-5p was able to inhibit the stemness potency of HCC by decreasing the number and size of tumorspheres, downregulating the expression of CSC biomarkers and hampering the ability of tumorigenesis in NOD/SCID mice. Brahma-related gene-1 (Brg1), as the target protein of miR-296-5p detected by bioinformatics methods, activates a series of downstream cascades through directly binding to Sall4 promoter and enhancing Sall4 transcription. Importantly, the higher expressions of Brg1 and Sall4 in tumor tissues of HCC patients suggest poorer prognoses after surgical extraction. In conclusion, miR-296-5p exerts an inhibitory effect on stemness potency of HCC cells via Brg1/Sall4 axis.

MiR-381-3p suppresses biological characteristics of cancer in head-neck squamous cell carcinoma cells by targeting nuclear autoantigenic sperm protein (NASP)

MiR-381-3p and nuclear autoantigenic sperm protein (NASP) have regulatory functions in tumors. Whether NASP is targeted by miR-381-3p to influence biological characteristics of cancer in head-neck squamous cell carcinoma (HNSCC) cells was investigated. StarBase (version 3.0) found that the expression of NASP was increased with the down-regulation of miR-381-3p in laryngocarcinoma tissue, AMC-HN-3，FaDu，HNE-3，and Detroit 562 cell lines. MiR-381-3p could target NASP, reduce the expression of MMP-2 and MMP-9, Vimentin, repress the cell viability, invasion, and migration, and promote the expression of E-cadherin in AMC-HN-3 cells. Overexpressed NASP could increase the viability, migration and invasion rates in AMC-HN-3 cells, which could be partially reversed by overexpressed miR-381-3p. Thus, miR-381-3p targeted and suppressed NASP gene, reduced the viability, migration, invasion, EMT of HNSCC cells, demonstrating that miR-381-3p has the potential to be a therapeutic target in inhibiting the progression of HNSCC.

MicroRNA-495 confers inhibitory effects on cancer stem cells in oral squamous cell carcinoma through the HOXC6-mediated TGF-β signaling pathway

Background

Oral squamous cell carcinoma (OSCC) is associated with high morbidity and ranks sixth among malignancies worldwide. Increasing evidence suggests that microRNAs (miRNAs or miRs) play a critical role in regulating cancer stem cells (CSCs), which drive the proliferation and spread of OSCC. Therefore, based on the alteration of aberrantly expressed miR-495 and homeobox C6 (HOXC6) by Gene Expression Omnibus (GEO) analysis, we subsequently explore the potential effect of miR-495 on the progression of CSCs in OSCC.

Methods

After the isolation of CSCs from the clinical tissue samples of OSCC patients, the expression of miR-495 and HOXC6 was determined, followed by the validation of the relationship between miR-495 and HOXC6. Subsequently, gain- and loss-function approach was performed to detect the role of miR-495 and HOXC6 in cell proliferation, migration, invasion, cell cycle entry, apoptosis, and epithelial-mesenchymal transition (EMT) of CSCs in OSCC, as well as the tumor growth in vivo.

Results

HOXC6 was highly expressed while miR-495 was poorly expressed in OSCC. HOXC6 was verified to be a target gene of miR-495, and miR-495 could inhibit the activation of the TGF-β signaling pathway. CSCs with miR-495 overexpression or HOXC6 silencing exhibited reversed EMT process; reduced abilities of proliferation, migration, and invasion; and promoted cell apoptosis in vitro. Moreover, inhibited tumor growth was observed in vivo after injection with miR-495 agomir or sh-HOXC6. In contrast, the downregulation of miR-495 showed an induced role in the progression of OSCC.

Conclusion

These findings suggest that miR-495 may suppress HOXC6 to inhibit EMT, proliferation, migration, and invasion while promoting apoptosis of CSCs in OSCC by inhibiting the TGF-β signaling pathway.

Regulation of cancer stem cell properties, angiogenesis, and vasculogenic mimicry by miR-450a-5p/SOX2 axis in colorectal cancer

Growing evidence indicates that a small number of cancer cells express stem cell markers and possess stem cell-like properties that promote malignant progression. Sex-determining region Y-box2 (SOX2) is a stem cell transcription factor essential for maintaining the properties of cancer stem cell (CSC). As CSC properties have been associated with angiogenesis and vasculogenic mimicry (VM), we aimed to comprehensively investigate whether SOX2 regulates CSC properties, angiogenesis, and VM in colorectal carcinoma (CRC) and its potential mechanism in this study. For this study, sphere formation assay, flow cytometry, cell survival analysis, tube formation, 3D culture, immunoblot, mouse model, and luciferase reporter assay were performed in vivo and in vitro. Expressions of SOX2 and miR-450a-5p in CRC tissue samples were examined through immunohistochemistry. First, the expression of SOX2 was not only associated with poor differentiation and prognosis but also promoted angiogenesis and VM. Knockdown of SOX2 ceased stemness properties, angiogenesis, and VM, along with decreased expression of CD133, CD31, and VE-cadherin as observed in functional experiments. Downregulation of SOX2 was found to inhibit tumorigenesis in vivo. Second, miR-450a-5p suppressed the expression of SOX2 by targeting its 3’UTR region directly and hence restrained SOX2-induced CSC properties, angiogenesis, and VM. Moreover, SOX2 overexpression preserved the miR-450a-5p-induced inhibition of CRC properties, angiogenesis, and VM. Finally, clinical samples exhibited a negative correlation between miR-450a-5p and SOX2. Patients with higher SOX2 and lower miR-450a-5p expressions had a poorer prognosis than patients with inverse expressions. Conclusively, we elucidated a unique mechanism of miR-450a-5p-SOX2 axis in the regulation of stemness, angiogenesis, and VM, which may act as a potential therapeutic practice in CRC.

miR-204 Negatively Regulates Cell Growth And Metastasis By Targeting ROBO4 In Human Bladder Cancer

Background

MicroRNAs (miRNAs) are well characterized for their important roles in human cancers by influencing various aspects of malignancy. Till now, the function and mechanism of miR-204, a tumor suppressor in several cancers, remain unclear in bladder cancer (BC). Here, we intend to explore its roles in BC progression.

Methods

qRT-PCR was applied to determine miR-204 and ROBO4 expression in BC tissues and cell lines. miR-204 expression with clinicopathological features was analyzed. The impacts of miR-204 on BC cell growth and metastasis in vitro were evaluated by both loss-of-function and gain-of-function assays (CCK-8, crystal violet staining, wound healing and transwell assays). Furthermore, qRT-PCR, Western blot and luciferase reporter assays were used to validate the targeting of ROBO4 by miR-204. Finally, linear regression was performed to analyze the correlation of miR-204 and ROBO4 in BC tissues.

Results

Expression of miR-204 was markedly decreased in BC tissues and cell lines were compared with respective controls. Low miR-204 expression was associated with positive advanced T stage and lymph node metastasis. Cellular function studies revealed that miR-204 inhibited BC cell growth, migration and invasion. Mechanistic exploration found that miR-204 directly targeted ROBO4. Rescue assays indicated that ROBO4 restoration could reverse the antitumor effects of miR-204 in BC. Finally, ROBO4 was significantly correlated with miR-204 levels inversely.

Conclusion

miR-204 might serve as a tumor suppressor in BC by targeting ROBO4.

Increased expression of miR-601 is associated with poor prognosis and tumor progression of gastric cancer

Background

MicroRNAs (miRNAs) have been considered to participate in many tumorigenesis, including gastric cancer (GC). Abnormal expression of miR-601 has been reported in GC, but its role is not clear. The goal of this study is to explore the expression patterns, clinical value and functional role of miR-601 in GC.

Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to evaluate the expression level of miR-601. The association between miR-601 expression and overall survival was estimated by the Kaplan-Meier survival method. The significance of different variables with respect to survival was analyzed by using the Cox regression assay. Cell experiments were applied to investigate the functional role of miR-601 in GC.

Results

We found that miR-601 was significantly up-regulated in GC tissues and cells compared with the controls (all P < 0.01). The levels of miR-601 expression were significantly associated with TNM stage, lymph node metastasis, lymphatic invasion, and distant metastasis (all P < 0.05). Kaplan-Meier survival analysis showed that patients in the high miR-601 expression group had poor overall survival (log-rank P = 0.001). Moreover, we confirmed that miR-601, TNM stage, and distant metastasis were independent prognostic factors for GC patients. Overexpression of miR-601 in AGS and SGC-7901 cells by miR-601 mimic transfection significantly promoted the cell proliferation, migration, and invasion (P < 0.05).

Conclusions

The expression level of miR-601 is dramatically up-regulated in GC. The overexpression of miR-601 promotes the tumor progression of GC, and may be a novel prognostic factor for poor survival in GC patients.

miR-638 represses the stem cell characteristics of breast cancer cells by targeting E2F2

OBJECTIVE

The miR-638 acted as a tumor suppressor and E2F transcription factor 2 (E2F2) was a critical regulator in some cancers, while the role of them on stemness of breast cancer stem cells (BCSCs) was rarely detailed. Hence, we focused on exploring the effects of miR-638 and E2F2 on BCSCs stemness.

METHODS

The proportion of CD24 -/CD44 + cells of BCSCs was detected by flow cytometry. The target relationship of miR-638 and E2F2 was explored using luciferase assays. The ability of self-renewal, proliferation, and invasion of BCSCs were determined by Mammosphere forming, Cell Counting Kit-8 (CCK-8), colony formation, and transwell assays. Xenograft tumor was established to detect the influence of miR-638 on tumor growth.

RESULTS

miR-638 was down-regulated, while E2F2 was elevated in breast cancer. The E2F2 level was negatively correlated with miR-638. The BCSCs represented higher proportion of CD24 -/CD44 + cells and levels of sex determining region Y-box 2 (SOX2) and octamer-binding transcription factor 4 (OCT4). The miR-638 was down-regulated and E2F2 was increased in BCSCs. MiR-638 could target to E2F2 and decreased the level of E2F2 in BCSCs cells. Overexpression of miR-638 decreased the proportion of CD24 -/CD44 + cells and the levels of SOX2 and OCT4 by inhibiting E2F2. The overexpression of miR-638 also inhibited the abilities of self-renewal, proliferation, and invasion of BCSCs by inhibiting E2F2. The miR-638 overexpression inhibited the breast tumor growth.

CONCLUSION

MiR-638 represses the characteristics and behaviors of BCSCs by targeting E2F2. MiR-638 may be a potential target for breast cancer therapy.

Role of miRNA-Regulated Cancer Stem Cells in the Pathogenesis of Human Malignancies

Recent biomedical discoveries have revolutionized the concept and understanding of carcinogenesis, a complex and multistep phenomenon which involves accretion of genetic, epigenetic, biochemical, and histological changes, with special reference to MicroRNAs (miRNAs) and cancer stem cells (CSCs). miRNAs are small noncoding molecules known to regulate expression of more than 60% of the human genes, and their aberrant expression has been associated with the pathogenesis of human cancers and the regulation of stemness features of CSCs. CSCs are the small population of cells present in human malignancies well-known for cancer resistance, relapse, tumorigenesis, and poor clinical outcome which compels the development of novel and effective therapeutic protocols for better clinical outcome. Interestingly, the role of miRNAs in maintaining and regulating the functioning of CSCs through targeting various oncogenic signaling pathways, such as Notch, wingless (WNT)/β-Catenin, janus kinases/ signal transducer and activator of transcription (JAK/STAT), phosphatidylinositol 3-kinase/ protein kinase B (PI3/AKT), and nuclear factor kappa-light-chain-enhancer of activated B (NF-kB), is critical and poses a huge challenge to cancer treatment. Based on recent findings, here, we have documented the regulatory action or the underlying mechanisms of how miRNAs affect the signaling pathways attributed to stemness features of CSCs, such as self-renewal, differentiation, epithelial to mesenchymal transition (EMT), metastasis, resistance and recurrence etc., associated with the pathogenesis of various types of human malignancies including colorectal cancer, lung cancer, breast cancer, head and neck cancer, prostate cancer, liver cancer, etc. We also shed light on the fact that the targeted attenuation of deregulated functioning of miRNA related to stemness in human carcinogenesis could be a viable approach for cancer treatment.

Potential Five-MicroRNA Signature Model for the Prediction of Prognosis in Patients with Wilms Tumor

Background

Wilms tumor (WT) is the most common type of pediatric renal malignancy, and is associated with poor prognosis. The aim of the present study was to identify microRNA (miRNA) signatures which might predict prognosis and categorize WTs into high- and low-risk subgroups.

Material/Methods

The miRNA expression profiles of WT patients and normal samples were obtained from the Therapeutically Applicable Research to Generate Effective Treatment database. Differentially expressed miRNAs between WT patients and normal samples were identified using the EdgeR package. Subsequently, correlations between differentially expressed miRNAs and the prognosis of overall survival were analyzed. Enrichment analyses for the targeted mRNAs were conducted via the Database for Annotation, Visualization, and Integration Discovery.

Results

A total of 154 miRNAs were identified as differentially expressed in WT. Of those, 18 miRNAs were associated with overall survival (P<0.05). A prognostic signature of 5 differentially expressed miRNAs (i.e., has-mir-149, has-mir-7112, has-mir-940, has-mir-1248, and has-mir-490) was constructed to classify the patients into high- and low-risk subgroups. The targeted mRNAs of these prognostic miRNAs were primarily enriched in Gene Ontology terms (i.e., protein autophosphorylation, protein dephosphorylation, and stress-activated MAPK cascade) and the Kyoto Encyclopedia of Genes and Genomes signaling pathways (i.e., MAPK, AMPK, and PI3K-Akt).

Conclusions

The 5-miRNA signature model might be useful in determining the prognosis of WT patients. As a promising prediction tool, this prognosis signature might serve as a potential biomarker for WT patients.

Role of miRNAs in Melanoma Metastasis

Tumour metastasis is a multistep process. Melanoma is a highly aggressive cancer and metastasis accounts for the majority of patient deaths. microRNAs (miRNAs) are non-coding RNAs that affect the expression of their target genes. When aberrantly expressed they contribute to the development of melanoma. While miRNAs can act locally in the cell where they are synthesized, they can also influence the phenotype of neighboring melanoma cells or execute their function in the direct tumour microenvironment by modulating ECM (extracellular matrix) and the activity of fibroblasts, endothelial cells, and immune cells. miRNAs are involved in all stages of melanoma metastasis, including intravasation into the lumina of vessels, survival during circulation in cardiovascular or lymphatic systems, extravasation, and formation of the pre-metastatic niche in distant organs. miRNAs contribute to metabolic alterations that provide a selective advantage during melanoma progression. They play an important role in the development of drug resistance, including resistance to targeted therapies and immunotherapies. Distinct profiles of miRNA expression are detected at each step of melanoma development. Since miRNAs can be detected in liquid biopsies, they are considered biomarkers of early disease stages or response to treatment. This review summarizes recent findings regarding the role of miRNAs in melanoma metastasis.

Clinical Implication of MicroRNAs in Molecular Pathology: An Update for 2018

MicroRNAs (miRNAs) are poised to provide diagnostic, prognostic, and therapeutic targets for several diseases including malignancies for precision medicine applications. The miRNAs have immense potential in the clinical arena because they can be detected in the blood, serum, tissues (fresh and formalin-fixed paraffin-embedded), and fine-needle aspirate specimens. The most attractive feature of miRNA-based therapy is that a single miRNA could be useful for targeting multiple genes that are deregulated in cancers, which can be further investigated through systems biology and network analysis that may provide cancer-specific personalized therapy.

MiR-138-5p suppresses lung adenocarcinoma cell epithelial-mesenchymal transition, proliferation and metastasis by targeting ZEB2

BACKGROUND

MiR-138-5p is regarded as a tumour suppressor in many cancers. Transforming growth factor beta (TGF-β) often acts as a tumor promotor at the late stages of human cancers. However, the function of miR-138-5p on lung adenocarcinoma cells induced by TGF-β remains to be further confirmed.

METHODS

RT-qPCR was used to detect the expression of human lung adenocarcinoma tissues, adjacent normal tissues, and relative cell lines. When the lung adenocarcinoma cells A549 and H1299 were transfected with negative control (NC), miR-138-5p mimics and miR-138-5p inhibitor by lipofectamine3000 and treated with or without TGF-β1, the lung adenocarcinoma cell function was detected by Immunofluorescence, Western blotting (WB), cell counting Kit-8 (CCK8), colony formation, EdU, Wound-healing and Transwell assays. The relation between miR-138-5p and zinc finger E-box-binding homeobox 2 (ZEB2) was detected by RT-qPCR, WB, and Luciferase reporter assays. When ZEB2 was knocked down, the lung adenocarcinoma cell function was detected by WB, CCK8 and Transwell assays.

RESULTS

The expression of miR-138-5p was decreased in lung adenocarcinoma tissues and cell lines. When treated with or without TGF-β1, overexpression of miR-138-5p suppressed EMT, proliferation and metastasis of A549 and H1299. ZEB2 was verified as the direct target of miR-138-5p. Downregulation of ZEB2 suppressed EMT, proliferation and metastasis of lung adenocarcinoma cell, which could be reversed by miR-138-5p inhibitor.

CONCLUSIONS

MiR-138-5p inhibits epithelial-mesenchymal transition, growth and metastasis of lung adenocarcinoma cells through targeting ZEB2.

BMSCs and miR-124a ameliorated diabetic nephropathy via inhibiting notch signalling pathway

BMSCs are important in replacement therapy of diabetic nephropathy (DN). MiR‐124a exerts effect on the differentiation capability of pancreatic progenitor cells. The objective of this study was to explore the molecular mechanisms, the functions of miR‐124a and bone marrow mesenchymal stem cells (BMSCs) in the treatment of DN. Characterizations of BMSCs were identified using the inverted microscope and flow cytometer. The differentiations of BMSCs were analysed by immunofluorescence assay and DTZ staining. The expression levels of islet cell‐specific transcription factors, apoptosis‐related genes, podocytes‐related genes and Notch signalling components were detected using quantitative real‐time reverse transcription PCR (qRT‐PCR) and Western blot assays. The production of insulin secretion was detected by adopting radioimmunoassay. Cell proliferation and apoptosis abilities were detected by CCK‐8, flow cytometry and TUNEL assays. We found that BMSCs was induced into islet‐like cells and that miR‐124a could promote the BMSCs to differentiate into islet‐like cells. BMSCs in combination with miR‐124a regulated islet cell‐specific transcription factors, apoptosis‐related genes, podocytes‐related genes as well as the activity of Notch signalling pathway. However, BMSCs in combination with miR‐124a relieved renal lesion caused by DN and decreased podocyte apoptosis caused by HG. The protective effect of BMSCs in combination with miR‐124a was closely related to the inactivation of Notch signalling pathway. MSCs in combination with miR‐124a protected kidney tissue from impairment and inhibited nephrocyte apoptosis in DN.

Targeting Epigenetic Aberrations in Pancreatic Cancer, a New Path to Improve Patient Outcomes?

Pancreatic cancer has one of the highest mortality rates among all types of cancers. The disease is highly aggressive and typically diagnosed in late stage making it difficult to treat. Currently, the vast majority of therapeutic regimens have only modest curative effects, and most of them are in the surgical/neo-adjuvant setting. There is a great need for new and more effective treatment strategies in common clinical practice. Previously, pathogenesis of pancreatic cancer was attributed solely to genetic mutations; however, recent advancements in the field have demonstrated that aberrant activation of epigenetic pathways contributes significantly to the pathogenesis of the disease. The identification of these aberrant activated epigenetic pathways has revealed enticing targets for the use of epigenetic inhibitors to mitigate the phenotypic changes driven by these cascades. These pathways have been found to be responsible for overactivation of growth signaling pathways and silencing of tumor suppressors and other cell cycle checkpoints. Furthermore, new miRNA signatures have been uncovered in pancreatic ductal adenocarcinoma (PDAC) patients, further widening the window for therapeutic opportunity. There has been success in preclinical settings using both epigenetic inhibitors as well as miRNAs to slow disease progression and eliminate diseased tissues. In addition to their utility as anti-proliferative agents, the pharmacological inhibitors that target epigenetic regulators (referred to here as readers, writers, and erasers for their ability to recognize, deposit, and remove post-translational modifications) have the potential to reconfigure the epigenetic landscape of diseased cells and disrupt the cancerous phenotype. The potential to “reprogram” cancer cells to revert them to a healthy state presents great promise and merits further investigation.

Stemness-Attenuating miR-503-3p as a Paracrine Factor to Regulate Growth of Cancer Stem Cells

Cancer stem cells (CSCs) with self-renewal abilities endorse cellular heterogeneity, resulting in metastasis and recurrence. However, there are no promising therapeutics directed against CSCs. Herein, we found that miR-503-3p inhibited tumor growth via the regulation of CSC proliferation and self-renewal. miR-503-3p, isolated from human adipose stem cell- (ASC-) derived exosomes, suppressed initiation and progression of CSCs as determined by anchorage-dependent (colony formation) and anchorage-independent (tumorsphere formation) assays. The expression of pluripotency genes was significantly decreased in miR-503-3p-treated CSCs. Furthermore, xenografts, which received miR-503-3p, exhibited remarkably reduced tumor growth in vivo. Thus, miR-503-3p may function as a stemness-attenuating factor via cell-to-cell communications.

Identification of the tumor‑suppressive function of circular RNA FOXO3 in non‑small cell lung cancer through sponging miR‑155

Circular RNAs (circRNAs) are a class of endogenous noncoding RNAs that have been demonstrated to be potential regulators in the development and progression of various types of human cancer. However, little is known about their roles in cancer initiation and progression, particular in non-small cell lung cancer (NSCLC). In the present study, the expression level of circRNA-forkhead box O3 class (FOXO3) in NSCLC specimens was determined and its functional role was investigated in NSCLC cells. By performing Taq-man based RT-qPCR, it was identified that circRNA-FOXO3 was downregulated in NSCLC tissues and cell lines. Receiver operating curve analysis indicated that circRNA-FOXO3 had a relatively higher diagnostic accuracy. The functional relevance was further examined by biological assays. circRNA-FOXO3 significantly promoted the ability of cell proliferation, migration and invasion of NSCLC cells. The linear isomer of circRNA-FOXO3, FOXO3 gene, was identified as a downstream target. RNA immunoprecipitation indicated that circRNA-FOXO3 sequestering miR-155, which further promoted linear FOXO3 expression. In addition, gain and loss functional assays indicated that circRNA-FOXO3 served an anti-oncogenic role through sequestering miR-155 and enhancing FOXO3 expression. These results suggest that circRNA-FOXO3 is a tumor-suppressor in NSCLC and may serve as a promising therapeutic target. Therefore, restoration of circRNA-FOXO3 expression could be a future approach to develop a novel treatment strategy.

MicroRNA‑543 inhibits proliferation, invasion and induces apoptosis of glioblastoma cells by directly targeting ADAM9

Glioma is the most common type of malignant brain tumor in humans and accounts for 81% of all malignant brain tumor cases in adults. The abnormal expression of microRNAs (miRs) has been reported to be important in the formation and progression of various types of human cancer, including glioblastoma (GBM). Therefore, studies into the expression, and roles of microRNAs as diagnostic and prognostic markers, as well as their therapeutic value for patients with GBM are warranted. The expression and roles of miR‑543 have been reported in several types of human cancer. However, the role of miR‑543 in GBM remains unclear. In the current study, the expression pattern of miR‑543 in GBM, the effects of miR‑543 on GBM cells and the underlying molecular mechanism was determined. The results of the present study demonstrated that miR‑543 was significantly downregulated in GBM tissue samples and cell lines. Furthermore, the upregulation of miR‑543 inhibited GBM cell proliferation and invasion, as well as promoted cell apoptosis. In addition, a disintegrin and metalloproteinase 9 (ADAM9) was identified to be a direct target gene of miR‑543. Furthermore, ADAM9 was significantly upregulated in GBM tissue samples and its expression was inversely correlated with miR‑543 expression in GBM tissue, suggesting that miR‑543 downregulation may contribute to ADAM9 upregulation in GBM. Finally, the results of the rescue experiment indicated that ADAM9 overexpression significantly reversed the effects of miR‑543 on the proliferation, invasion and apoptosis of GBM cells, suggesting that miR‑543 serves as a tumor suppressor in GBM through ADAM9 regulation. Overall, these findings indicate that the miR‑543/ADAM9 signaling pathway may provide as a potential therapeutic strategy for GBM.

Four microRNAs Signature for Survival Prognosis in Colon Cancer using TCGA Data

This study aims to develop microRNA expression signature for colon cancer survival prognosis based on the Cancer Genomic Common database. miRNAs levels between colon cancer and non-cancer tissues were screened by t-test (p < 0.05). Kaplan-Meier survival method was used to discriminate survival significant miRNAs, followed by miRNAs index accumulation to power the miRNAs-survival reliability. In the end, we test the selected miRNAs in HT126 colon cancer cells to validate its anti-cancer effect. The study identified a 84-miRNAs signature. Of the above 84 miRNAs, we got four miRNAs which were survival associated by using ROC curve method and Kaplan-Meier survival method (p < 0.001). The result showed that low risk group had quite a low death rate, the survival rate was over 80%. The high risk group had survival rate lower than 20%, which was also extremely lower than the overall survival rate. In the HT126 cells study, cell growth assay showed miR-130a sponge inhibited colon cancer cells growth and sensitized the anti-cancer drug effect of 5-FU to blocked cancer cell growth. We developed a prognostic 4-microRNA expression signature for colon cancer patient survival, and validated miR-130a sponge could sensitized 5-FU anti-cancer effect.

Maternal pre-pregnancy body mass index and circulating microRNAs in pregnancy

BACKGROUND

Maternal pre-pregnancy overweight and obese status has been associated with a number of pregnancy complications and adverse offspring outcomes. Mechanisms for observed associations, however, are largely unknown. We investigated associations of pre-pregnancy body mass index with early-mid pregnancy epigenetic biomarkers, circulating microRNAs.

METHODS

Peripheral blood was collected from participants (16-27 weeks gestation) of two multi-racial pregnancy cohorts, the Omega Study and the Pregnancy Outcomes and Community Health Study. Plasma miRNA expression was characterised using epigenome-wide (319 miRNAs) profiling among 20 pregnant women in each cohort. Cohort-specific linear regression models that included the predictor (pre-pregnancy body mass index), the outcome (microRNA expression), and adjustment factors (maternal age, gestational age at blood collection, and race) were fit.

RESULTS

Expression of 27 miRNAs was positively associated with pre-pregnancy body mass index in both cohorts (p-values <0.05). A number of these differentially expressed miRNAs have previously been associated with adipogenesis (e.g. let-7d*, miR-103-2*, -130b, -146b-5-p, -29c, and -26b). Identified miRNAs as well as their experimentally validated targets participate in pathways that involve organismal injury, reproductive system disease, connective tissue disorders, cancer, cellular development, growth and proliferation.

CONCLUSION

Pre-pregnancy body mass index is associated with circulating miRNAs in early-mid pregnancy.

Roles of microRNA-99 family in human glioma

Objective

Deregulation of microRNA (miR)-99 family members (miR-99a, miR-99b, and miR-100) has been reported to play a crucial role in many cancer types. However, their roles in human gliomas have not been fully elucidated. This study aimed to investigate the expression patterns of miR-99a, miR-99b, and miR-100 in glioma tissues and to evaluate their expression profiles with respect to tumor progression.

Methods

Quantitative real-time polymerase chain reaction was performed to detect the expression levels of miR-99a, miR-99b, and miR-100 in glioma and matched non-neoplastic brain tissues. Then, the associations of their expression with various clinicopathological features of glioma patients were statistically analyzed. Moreover, the roles of miR-99a, miR-99b, and miR-100 in regulating glioma cell migration and invasion were determined via transwell assay in vitro.

Results

Compared with non-neoplastic brain tissues, miR-99a, miR-99b, and miR-100 expression levels were all significantly decreased in glioma tissues (all P<0.001). miR-99a-low, miR-99b-low, and miR-100-low expression more frequently occurred in glioma patients with low Karnofsky performance score (<90) and high World Health Organization grade (III–IV). Further functional experiments revealed that the enforced expression of miR-99a, miR-99b, and miR-100 resulted in the inhibition of cellular migration and invasion in glioma cells.

Conclusion

Our results strongly suggest that the aberrant expression of miR-99a, miR-99b, and miR-100 may be a common feature in human gliomas with aggressive clinicopathological features and may participate in malignant phenotypes of the tumors. These findings highlight the potential of the three miR-99 family members as novel therapeutic targets for human gliomas.

miRs-134 and -370 function as tumor suppressors in colorectal cancer by independently suppressing EGFR and PI3K signalling

Growth factor receptor signalling plays a central and critical role in colorectal cancer. Most importantly, the EGFR signalling cascade involving PI3K/AKT/mTOR and Raf/MEK/ERK pathways are particularly relevant, since they are commonly activated in several cancer entities, including colorectal cancer. In this study, we show that miRs-134 and -370 are both capable of regulating these pathways by targeting EGFR and PIK3CA. In three different colorectal cancer cell lines (DLD1, HCT-116 and RKO), suppression of EGFR and PIK3CA through the enhanced expression of miR-134 or -370 led to a suppression of the key molecules of the PI3K/AKT/mTOR pathway. Furthermore, overexpression of miR-134 or -370 resulted in a significant reduction of cell proliferation, colony formation, migration, invasion and in-vivo tumor growth and metastasis. Concurrent experiments with small interfering RNAs targeting the prime targets show that our selected miRNAs exert a greater functional influence and affect more downstream molecules than is seen with silencing of the individual proteins. Taken together, these data indicate that miRs-134 and -370 are potential tumour suppressor miRNAs and could play a fundamental role in suppressing colorectal cancer tumorigenesis through their ability to co-ordinately regulate EGFR signalling cascade by independently targeting EGFR and PIK3CA.

MicroRNA biogenesis and their functions in regulating stem cell potency and differentiation

Stem cells are unspecialized/undifferentiated cells that exist in embryos and adult tissues or can be converted from somatic differentiated cells. Use of stem cells for tissue regeneration and tissue engineering has been a cornerstone of the regenerative medicine. Stem cells are also believed to exist in cancer tissues, namely cancer stem cells (CSCs). Growing evidence suggests that CSCs are the culprit of cancer dormancy, progression and recurrence, and thus have recently received great attention. MicroRNAs (miRNAs) are a group of short, non-coding RNAs that regulate expression of a wide range of genes at a post-transcriptional manner. They are emerging as key regulators of stem cell behaviors. This mini review summarizes the basic biogenesis and mode of actions of miRNAs, recent progress and discoveries of miRNAs in cellular reprogramming, stem cell differentiation and cellular communication, as well as miRNAs in CSCs. Some potential of miRNAs in future biomedical applications and research pertaining to stem cells are briefly discussed.

Inhibition of heat-shock protein 90 sensitizes liver cancer stem-like cells to magnetic hyperthermia and enhances anti-tumor effect on hepatocellular carcinoma-burdened nude mice

PURPOSE

To explore the thermoresistance and expression of heat-shock protein 90 (HSP90) in magnetic hyperthermia-treated human liver cancer stem-like cells (LCSCs) and the effects of a heat-shock protein HSP90 inhibitor 17-allylamino-17-demethoxgeldanamycin (17-AAG) on hepatocellular carcinoma-burdened nude mice.

METHODS

CD90(+) LCSCs were isolated by magnetic-activated cell sorting from BEL-7404. Spheroid formation, proliferation, differentiation, drug resistance, and tumor formation assays were performed to identify stem cell characteristics. CD90-targeted thermosensitive magnetoliposomes (TMs)-encapsulated 17-AAG (CD90@17-AAG/TMs) was prepared by reverse-phase evaporation and its characteristics were studied. Heat tolerance in CD90(+) LCSCs and the effect of CD90@17-AAG/TMs-mediated heat sensitivity were examined in vitro and in vivo.

RESULTS

CD90(+) LCSCs showed significant stem cell-like properties. The 17-AAG/TMs were successfully prepared and were spherical in shape with an average size of 128.9±7.7 nm. When exposed to magnetic hyperthermia, HSP90 was up-regulated in CD90(+) LCSCs. CD90@17-AAG/TMs inhibited the activity of HSP90 and increased the sensitivity of CD90(+) LCSCs to magnetic hyperthermia.

CONCLUSION

The inhibition of HSP90 could sensitize CD90(+) LCSCs to magnetic hyperthermia and enhance its anti-tumor effects in vitro and in vivo.