MicroRNA-26b inhibits metastasis of osteosarcoma via targeting CTGF and Smad1

Interactions between achiral porphyrins and a mature miRNA

Recent discoveries have revealed that mature miRNAs could form highly ordered structures similar to aptamers, suggesting diverse functions beyond mRNA recognition and degradation. This study focuses on understanding the secondary structures of human miR-26b-5p (UUCAAGUAAUUCAGGAUAGGU) using circular dichroism (CD) and chiroptical probes; in particular, four achiral porphyrins were utilized to both act as chiroptical probes and influence miRNA thermodynamic stability. Various spectroscopic techniques, including UV-Vis, fluorescence, resonance light scattering (RLS), electronic circular dichroism (ECD), and CD melting, were employed to study their interactions. UV-Vis titration revealed that meso-tetrakis(4-N-methylpyridyl) porphyrin (H2T4) and meso-tetrakis(4-carboxyphenylspermine) porphyrin (H2TCPPSpm4) formed complexes with distinct binding stoichiometries up to 6 : 1 and 3 : 1 ratios, respectively, and these results were supported by RLS and fluorescence, while the zinc(II) derivative porphyrin ZnT4 exhibited a weaker interaction. ZnTCPPSpm4 formed aggregates in PBS with higher organization in the presence of miRNA. CD titrations displayed an induced CD signal in the Soret region for every porphyrin investigated, indicating that they can be used as chiroptical probes for miR-26b-5p. Lastly, CD melting experiments revealed that at a 1 : 1 ratio, porphyrins did not significantly affect miRNA stability, except for H2TCPPSpm4. However, at a 3 : 1 ratio, all porphyrins, except ZnTCPPSpm4, exhibited a strong destabilizing effect on miRNA secondary structures. These findings shed light on the structural versatility of miR-26b-5p and highlight the potential of porphyrins as chiroptical probes and modulators of miRNA stability.

Reconstruction of tissue-specific genome-scale metabolic models for human cancer stem cells

Cancer Stem Cells (CSCs) contribute to cancer aggressiveness, metastasis, chemo/radio-therapy resistance, and tumor recurrence. Recent studies emphasized the importance of metabolic reprogramming of CSCs for the maintenance and progression of the cancer phenotype through both the fulfillment of the energetic requirements and the supply of substrates fundamental for fast-cell growth, as well as through metabolite-induced epigenetic regulation. Therefore, it is of paramount importance to develop therapeutic strategies tailored to target the metabolism of CSCs. In this work, we built computational Genome-Scale Metabolic Models (GSMMs) for CSCs of different tissues. Flux simulations were then used to predict metabolic phenotypes, identify potential therapeutic targets, and spot already-known Transcription Factors (TFs), miRNAs and antimetabolites that could be used as part of drug repurposing strategies against cancer. Results were in accordance with experimental evidence, provided insights of new metabolic mechanisms for already known agents, and allowed for the identification of potential new targets and compounds that could be interesting for further in vitro and in vivo validation.

RAB31 is targeted by miR-26b and serves a role in the promotion of osteosarcoma

Ras-related protein Rab-31 (RAB31), a small guanosine 5'-triphosphate-binding protein, is a member of the Rab family and has been demonstrated to serve an oncogenic role in several common types of human cancer. However, the function of RAB31 in osteosarcoma (OS) has not been previously studied. The present study identified that the expression levels of RAB31 were significantly higher in OS tissue samples compared with matched adjacent non-tumor tissue samples, and high RAB31 expression was associated with malignant progression and a poor prognosis for patients with OS. Furthermore, it was identified that the expression levels of RAB31 were increased in OS cell lines compared with normal osteoblast cells. Silencing of RAB31 expression significantly inhibited OS cell proliferation, cell cycle progression, migration and invasion, and significantly increased the rate of cell apoptosis. In addition, the present study used a luciferase reporter assay to demonstrate that RAB31 was a direct target gene of microRNA-26b (miR-26b), which is a known tumor suppressor in OS. The expression levels of RAB31 were negatively associated with miR-26b expression in OS cells. Finally, miR-26b was demonstrated to be significantly decreased in OS tissues compared with adjacent non-tumor tissues, and an inverse correlation was observed between the expression levels of RAB31 and miR-26b in OS tissues. In summary, to the best of our knowledge, the present study is the first to report that RAB31 is a target gene of miR-26b, and silencing of RAB31 may inhibit OS growth and progression.

Human mesenchymal stromal cells and derived extracellular vesicles: Translational strategies to increase their proangiogenic potential for the treatment of cardiovascular disease

Mesenchymal stromal cells (MSCs) offer great potential for the treatment of cardiovascular diseases (CVDs) such as myocardial infarction and heart failure. Studies have revealed that the efficacy of MSCs is mainly attributed to their capacity to secrete numerous trophic factors that promote angiogenesis, inhibit apoptosis, and modulate the immune response. There is growing evidence that MSC‐derived extracellular vesicles (EVs) containing a cargo of lipids, proteins, metabolites, and RNAs play a key role in this paracrine mechanism. In particular, encapsulated microRNAs have been identified as important positive regulators of angiogenesis in pathological settings of insufficient blood supply to the heart, thus opening a new path for the treatment of CVD. In the present review, we discuss the current knowledge related to the proangiogenic potential of MSCs and MSC‐derived EVs as well as methods to enhance their biological activities for improved cardiac tissue repair. Increasing our understanding of mechanisms supporting angiogenesis will help optimize future approaches to CVD intervention.

MicroRNA-584 Impairs Cellular Proliferation and Sensitizes Osteosarcoma Cells to Cisplatin and Taxanes by Targeting CCN2

Background

Osteosarcoma (OS), an aggressive malignant neoplasm, exhibits osteoblastic differentiation. Cisplatin (DDP) and taxanes are among the most effective drugs for OS patients. Nevertheless, the drug resistance remains a main limitation to efficacious chemotherapy in OS. The current report sets to explore the biological function of microRNA-584 (miR-584) and the potential mechanism underlying OS cells resistance to these two drugs.

Materials and Methods

The expression profiles of miR-584 and connective tissue growth factor (CTGF, CCN2) in OS tissue samples and cell lines were tested by means of reverse transcription-quantitative polymerase chain reaction and Western blot. U2OS and MG63 cell lines were delivered with miR-584 mimic alone or plus CCN2 to excavate theirs functions by cell counting kit-8 and EdU, flow cytometric analysis, as well as transwell assay, severally. Western bot analysis was conducted to examine the expression of IκBα, pIκBα, NF-κB and pNF-κB. Dual-luciferase reporter gene assay was carried out to assess the targets of miR-584.

Results

The downregulation of miR-584 was identified in OS tissues and cells, which was closely linked to the dismal prognosis of OS patients. Overexpression of miR-584 repressed cell viability, migration as well as invasion, potentiated apoptosis and sensitized OS cells to DDP and taxanes. Mechanism investigation specified a direct targeting relationship between CCN2 and miR-584 in OS.

Conclusion

In conclusion, miR-584 has the potency to act as a therapeutic maneuver for OS mainly by inducing the chemosensitivity of OS cells to DDP and taxanes.

Overexpression of connective tissue growth factor is associated with tumor progression and unfavorable prognosis in endometrial cancer

OBJECTIVES

This study was to explore the prognostic value of connective tissue growth factor (CTGF) expression in endometrial cancer (EC).

METHODS

We compared CTGF expression in 198 samples from patients with endometrial cancer and 50 samples from patients with healthy endometrial tissues as determined by immunohistochemistry.

RESULTS

Expression of CTGF was significantly higher in endometrial cancers as compared to normal endometrial tissues. Positive CTGF expression displayed a strong association with CA125 level, histological grade, depth of myometrial invasion and the International Federation of Gynecology and Obstetrics (FIGO) stage. Our findings revealed histological grade, depth of myometrial invasion, FIGO stage, vascular/lymphatic invasion, and the CTGF expression are related to 5-year survival in patients with endometrial cancer. Positive CTGF expression, lymph node status, as well as vascular/lymphatic invasion, were identified as independent prognostic factors in endometrial cancer.

CONCLUTIONS

Over-expression of CTGF is an independent prognostic factor that will allow the successful differentiation of high-risk population from the group of patients with stage III-IV endometrial cancer. The up-regulation of CTGF may contribute to the progression of endometrial cancer and serve as a new prognostic biomarker in patients with endometrial cancer survival.

miRNA signatures in childhood sarcomas and their clinical implications

Progresses in multimodal treatments have significantly improved the outcomes for childhood cancer. Nonetheless, for about one-third of patients with Ewing sarcoma, rhabdomyosarcoma, or osteosarcoma steady remission has remained intangible. Thus, new biomarkers to improve early diagnosis and the development of precision-targeted medicine remain imperative. Over the last decade, remarkable progress has been made in the basic understanding of miRNAs function and in interpreting the contribution of their dysregulation to cancer development and progression. On this basis, this review focuses on what has been learned about the pivotal roles of miRNAs in the regulation of key genes implicated in childhood sarcomas.

Loss of miR-198 and -206 during primary tumor progression enables metastatic dissemination in human osteosarcoma

The metastatic dissemination is a complex multistep process by which tumor cells from a primary site enter into the systemic circulation to finally spread at distant sites. Even if this mechanism is rare at the tumor level, it remains the major cause of Osteosarcoma-patients’ relapse and mortality. MicroRNAs (miRNAs) have recently been described as novel epigenetics’ genes’ expression regulators actively implicated in cancer progression and dissemination. The understanding of their implication in the metastatic spreading could help clinicians to improve the outcome of osteosarcoma. We established the miRNA’s expression-profile between primary bone-tumors (PTs), circulating tumor cells (CTCs) and lung metastatic (META) samples from in vivo mice xenograft models. Our results show that the expression level of the miR-198 and -206 was decreased in META samples, in which the expression of the metastasis-related receptor C-Met was up-regulated. Those expression variations were validated in osteosarcoma patient biopsies from matching primary tumors and lung metastasis. We validated in vitro the endogenous miRNAs inhibitory effects on both migration and invasion, as well as we confirmed by luciferase assays that the C-Met receptor is one of their bona-fide targets. The anti-metastatic effect of these miRNAs was also validated in vivo, as their direct injections into the tumors reduce the number of lung-metastases and prolongs the overall survival of the treated animals. All together, our results suggest the absence of the miR-198 and -206 as powerful predictive biomarkers of the tumor cell dissemination and the rationale of their potential therapeutic use in the treatment of Osteosarcoma.

Phenotypic miRNA Screen Identifies miR-26b to Promote the Growth and Survival of Endothelial Cells

Endothelial cell (EC) proliferation is a crucial event in physiological and pathological angiogenesis. MicroRNAs (miRNAs) have emerged as important modulators of the angiogenic switch. Here we conducted high-content screening of a human miRNA mimic library to identify novel regulators of EC growth systematically. Several miRNAs were nominated that enhanced or inhibited EC growth. Of these, we focused on miR-26b, which is a conserved candidate and expressed in multiple human EC types. miR-26b overexpression enhanced EC proliferation, migration, and tube formation, while inhibition of miR-26b suppressed the proliferative and angiogenic capacity of ECs. A combinatory functional small interfering RNA (siRNA) screening of 48 predicted gene targets revealed that miR-26b enhanced EC growth and survival through inhibiting PTEN expression. Local administration of miR-26b mimics promoted the growth of new microvessels in the Matrigel plug model. In the mouse model of hindlimb ischemia, miR-26b was found to be downregulated in endothelium in the first week following ischemia, and local overexpression of miR-26b improved the survival of capillaries and muscle fibers in ischemic muscles. Our findings suggest that miR-26b enhances EC proliferation, survival, and angiogenesis. miR-26b is a potential target for developing novel pro-angiogenic therapeutics in ischemic disease.

MicroRNA-645 promotes metastasis of osteosarcoma via targeting tumor suppressor NM23 nucleoside diphosphate kinase 2

Osteosarcoma is the most common non-hematological primary bony malignancy in children and young adults with tumor metastasis being a common event at diagnosis. Understanding the pathogenesis of metastatic osteosarcoma may help identify potential therapeutic targets. In this study, we found that the level of microRNA-645 (miR-645) in osteosarcoma tumor tissues was significantly increased compared with their paired non-tumorous tissues, and was associated with histologic grade, TNM staging, lymph metastasis and distant metastasis. Knockdown of miR-645 caused a remarkable inhibition of migration of osteosarcoma U2OS cells. Furthermore, miR-645 inhibited NME2 (nucleoside diphosphate kinase 2) expression through directly binding to its 3' untranslated region. In human osteosarcoma tissues, we also found that NME2 was significantly decreased in tumor tissues, and its level was negatively correlated with miR-645. In addition, silencing NME2 attenuated the decreased cell migration by knockdown of miR-645, suggesting that it was involved in the miR-645 induced cell migration of osteosarcoma cells. Taken together, we found that miR-645 was up-regulated in osteosarcoma tissues and could promote osteosarcoma cell migration through directly inhibiting the tumor suppressor NME2. Our data provide novel insight into the role of miR-645 in osteosarcoma and indicate that miR-645 might be a potential therapeutic target of osteosarcoma.

Connective tissue growth factor stimulates osteosarcoma cell migration and induces osteosarcoma metastasis by upregulating VCAM-1 expression

Osteosarcoma is the most common bone malignancy that occurs in the young population. After osteosarcoma cells metastasize to the lung, prognosis is very poor owing to difficulties in early diagnosis and effective treatment. Recently, connective tissue growth factor (CTGF) was reported to be a critical contributor to osteosarcoma metastasis. However, the detailed mechanism associated with CTGF-directed migration in bone neoplasms is still mostly unknown. Through the in vivo and in vitro examination of osteosarcoma cells, this study suggests that VCAM-1 up-regulation and increased osteosarcoma cell migration are involved in this process. Antagonizing αvβ3 integrin inhibited cell migration. Moreover, FAK, PI3K, Akt and NF-κB activation were also shown to be involved in CTGF-mediated osteosarcoma metastasis. Taken together, CTGF promotes VCAM-1 production and further induces osteosarcoma metastasis via the αvβ3 integrin/FAK/PI3K/Akt/NF-κB signaling pathway, which could represent a promising clinical target to improve patient outcome.

Identification of the miRNA-mRNA regulatory network of small cell osteosarcoma based on RNA-seq

Small cell osteosarcoma (SCO) is a rare subtype of osteosarcoma characterized by highly aggressive progression and a poor prognosis. The miRNA and mRNA expression profiles of peripheral blood mononuclear cells (PBMCs) were obtained in 3 patients with SCO and 10 healthy individuals using high-throughput RNA-sequencing. We identified 37 dysregulated miRNAs and 1636 dysregulated mRNAs in patients with SCO compared to the healthy controls. Specifically, the 37 dysregulated miRNAs consisted of 27 up-regulated miRNAs and 10 down-regulated miRNAs; the 1636 dysregulated mRNAs consisted of 555 up-regulated mRNAs and 1081 down-regulated mRNAs. The target-genes of miRNAs were predicted, and 1334 negative correlations between miRNAs and mRNAs were used to construct an miRNA-mRNA regulatory network. Dysregulated genes were significantly enriched in pathways related to cancer, mTOR signaling and cell cycle signaling. Specifically, hsa-miR-26b-5p, hsa-miR-221-3p and hsa-miR-125b-2-3p were significantly dysregulated miRNAs and exhibited a high degree of connectivity with target genes. Overall, the expression of dysregulated genes in tumor tissues and peripheral blood samples of patients with SCO measured by quantitative real-time polymerase chain reaction corroborated with our bioinformatics analyses based on the expression profiles of PBMCs from patients with SCO. Thus, hsa-miR-26b-5p, hsa-miR-221-3p and hsa-miR-125b-2-3p may be involved in SCO tumorigenesis.

lncRNA PVT1 promotes the angiogenesis of vascular endothelial cell by targeting miR‑26b to activate CTGF/ANGPT2

Angiogenesis is essential for various biological processes, including tumor blood supply delivery, cancer cell growth, invasion and metastasis. Plasmacytoma variant translocation 1 (PVT1) long noncoding RNA (lncRNA) has been previously reported to affect angiogenesis of glioma microvascular endothelial cells by regulating microRNA (miR)‑186 expression level. However, the specific underlying molecular mechanism of PVT1 regulation of angiogenesis in vascular endothelial cells remains to be elucidated. The present study investigated the role of PVT1 in cell proliferation, migration and vascular tube formation of human umbilical vein endothelial cells (HUVECs) using MTT assay, Transwell migration assay and in vitro vascular tube formation assay, respectively. In order to determine the effect of miR‑26b on cell proliferation, migration and vascular tube formation of HUVECs, miR‑26 mimic or miR‑26b inhibitor were transfected into HUVECs. Reverse transcription‑quantitative polymerase chain reaction and western blotting were conducted to quantify the mRNA and protein expression levels of target genes. The present study confirmed that miR‑26b bound 3'‑untranslated region (3'‑UTR) and subsequently influenced gene expression level using dual luciferase reporter assay. The current study observed that PVT1 affected cell proliferation, migration and in vitro vascular tube formation of HUVECs. In addition, it was determined that PVT1 was able to bind and degrade miR‑26b to promote connective tissue growth factor (CTGF) and angiopoietin 2 (ANGPT2) expression. miR‑26b was also identified to have a suppressive role in cell proliferation, migration and in vitro vascular tube formation of HUVECs via binding 3'‑UTR regions and downregulating CTGF and ANGPT2 expression levels. The current findings may improve the understanding of the underlying mechanism of PVT1 contributing to angiogenesis of vascular endothelial cells and offer rationale for targeting PVT1 to treat angiogenesis dysfunction‑associated diseases, including cancer metastasis.

MicroRNAs for osteosarcoma in the mouse: a meta-analysis

Osteosarcoma (OS) is the most common primary malignant bone carcinoma with high morbidity that happens mainly in children and young adults. As the key components of gene-regulatory networks, microRNAs (miRNAs) control many critical pathophysiological processes, including initiation and progression of cancers. The objective of this study is to summarize and evaluate the potential of miRNAs as targets for prevention and treatment of OS in mouse models, and to explore the methodological quality of current studies. We searched PubMed, Web of Science, Embase, Wan Fang Database, VIP Database, China Knowledge Resource Integrated Database, and Chinese BioMedical since their beginning date to 10 May 2016. Two reviewers separately screened the controlled studies, which estimate the effects of miRNAs on osteosarcoma in mice. A pair-wise analysis was performed. Thirty six studies with enough randomization were selected and included in the meta-analysis. We found that blocking oncogenic or restoring decreased miRNAs in cancer cells could significantly suppress the progression of OS in vivo, as assessed by tumor volume and tumor weight. This meta-analysis suggests that miRNAs are potential therapeutic targets for OS and correction of the altered expression of miRNAs significantly suppresses the progression of OS in mouse models, however, the overall methodological quality of studies included here was low, and more animal studies with the rigourous design must be carried out before a miRNA-based treatment could be translated from animal studies to clinical trials.

MicroRNA-26b inhibits tumor metastasis by targeting the KPNA2/c-jun pathway in human gastric cancer

MicroRNAs (miRNA) play an important role in carcinogenesis. Previously, we identified miR-26b as a significantly downregulated miRNA in gastric cancer (GC) tissues (n = 106) based on differential quantitative RT-PCR (RT-qPCR) miRNA expression profiles. In the current study, we aimed to clarify the potential role of miR-26b and related target genes in GC progression. Downregulation of miR-26b was associated with advanced tumor-node-metastasis stage (TNM stage) and poor 5-year survival rate. Forced expression of miR-26b led to inhibition of GC cell migration and invasion in vitro and lung metastasis formation in vivo. Conversely, depletion of miR-26b had stimulatory effects. Additionally, miR-26b affected GC cell behavior through negative regulation of the metastasis promoter, karyopherin alpha 2 (KPNA2). Ectopic expression of miR-26b induced a reduction in KPNA2 protein levels, confirmed by luciferase assay data showing that miR-26b directly binds to the 3' untranslated regions (UTR) of KPNA2 mRNA. Furthermore, miR-26b and KPNA2 mRNA/protein expression patterns were inversely correlated in GC tissues. Cag A of Helicobacter pylori (Hp) enhanced miR-26b levels through regulation of the KPNA2/c-jun pathway. Taken together, our data indicate that miR-26b plays an anti-metastatic role and is downregulated in GC tissues via the KPNA2/c-jun pathway. Based on the study findings, we propose that miR-26b overexpression or KPNA2/c-jun suppression may have therapeutic potential in inhibiting GC metastasis.

Intermittent hypoxia caused cognitive dysfunction relate to miRNAs dysregulation in hippocampus

Intermittent hypoxia (IH) is a characteristic pathophysiological change of obstructive sleep apnea (OSA), a commonly diagnosed chronic sleep disorder. With the process of OSA, patients will suffer from the nervous system damage and appear to multiple cognitive dysfunction. The mechanism that how IH causes cognitive impairment is still unknown. Both control and experimental rats were placed in conditions absence and presence of intermittent hypoxia (IH) for 8h a day for a week, two weeks and four weeks, and then followed by behavioral assessments with Morris Water Maze (MWM) test. The results showed that the escape latency of the tested animals to IH significantly increased the escape latency on the last four training days in comparison to the control group. Consistent with this, the expressions of apoptosis/anti-apoptosis proteins were both changed in the hippocampus. Then we utilized the miRNA microarray assay to investigate the level of miRNA expression in rat hippocampus which suffered from intermittent hypoxia. It is noteworthy that the expressions of miR-26b and miR-207 were consistently dysregulated in all the experimental groups post IH. And we utilized qRT-PCR methods to verify the microarray results. Our results showed that microarray based analysis of microRNA expression in rat hippocampus after IH has shown that some microRNAs such as miR-26b and miR-207 could be involved in the OSA-induced cognitive impairments.

CircRNA_000203 enhances the expression of fibrosis-associated genes by derepressing targets of miR-26b-5p, Col1a2 and CTGF, in cardiac fibroblasts

Circular RNAs (circRNAs) participate in regulating gene expression in diverse biological and pathological processes. The present study aimed to investigate the mechanism underlying the modulation of circRNA_000203 on expressions of fibrosis-associated genes in cardiac fibroblasts. CircRNA_000203 was shown upregulated in the diabetic mouse myocardium and in Ang-II-induced mouse cardiac fibroblasts. Enforced-expression of circRNA_000203 could increase expressions of Col1a2, Col3a1 and α-SMA in mouse cardiac fibroblasts. RNA pull-down and RT-qPCR assay indicated that circRNA_000203 could specifically sponge miR-26b-5p. Dual luciferase reporter assay revealed that miR-26b-5p interacted with 3′UTRs of Col1a2 and CTGF, and circ_000203 could block the interactions of miR-26b-5p and 3′UTRs of Col1a2 and CTGF. Transfection of miR-26b-5p could post-transcriptionaly inhibit expressions of Col1a2 and CTGF, accompanied with the suppressions of Col3a1 and α-SMA in cardiac fibroblasts. Additionally, over-expression of circRNA_000203 could eliminate the anti-fibrosis effect of miR-26b-5p in cardiac fibroblasts. Together, our results reveal that suppressing the function of miR-26b-5p contributes to the pro-fibrosis effect of circRNA_000203 in cardiac fibroblasts.

Overexpression of miR-26b-5p regulates the cell cycle by targeting CCND2 in GC-2 cells under exposure to extremely low frequency electromagnetic fields

The increasing prevalence of extremely low frequency electromagnetic fields (ELF-EMFs) exposure has raised considerable public concern regarding the potential hazardous effects of ELF-EMFs on male reproductive function. Increasing evidence indicates that miRNAs are necessary for spermatogenesis and male fertility. However, the regulation of miRNA expression and the roles of miRNAs in response to ELF-EMFs remain unclear. In our study, mouse spermatocyte-derived GC-2 cells were intermittently exposed to a 50 Hz ELF-EMF for 72 h (5 min on/10 min off) at magnetic field intensities of 1 mT, 2 mT and 3 mT. MiR-26b-5p was differentially expressed in response to different magnetic field intensities of ELF-EMFs. The host gene CTDSP1 showed an unmethylation status in GC-2 cells at different magnetic field intensities of ELF-EMF exposure. MiR-26b-5p had no significant, obvious influence on the cell viability, apoptosis or cell cycle of GC-2 cells. However, the overexpression of miR-26b-5p significantly decreased the percentage of G0/G1 phase cells and slightly increased the percentage of S phase cells compared to the sham group that was exposed to a 50 Hz ELF-EMF. Computational algorithms identified Cyclin D2 (CCND2) as a direct target of miR-26b-5p. MiR-26b-5p and a 50 Hz ELF-EMF altered the expression of CCND2 at both the mRNA and protein levels. Overexpressed miR-26b-5p in GC-2 cells can change the mRNA expression of CCND2 following 50 Hz ELF-EMF at 3 mT. These findings demonstrate that miR-26b-5p could serve as a potential biomarker following 50 Hz ELF-EMF exposure, and miR-26b-5p-CCND2-mediated cell cycle regulation might play a pivotal role in the biological effects of ELF-EMFs.

4-cholesten-3-one suppresses lung adenocarcinoma metastasis by regulating translocation of HMGB1, HIF1α and Caveolin-1

Metastasis is a great challenge in lung adenocarcinoma (ADC) therapy. Cholesterol has been implicated in ADC metastasis. 4-cholesten-3-one, as cholesterol metabolite and analog, can substitute membrane cholesterol and increase membrane fluidity. In this study, we explored the possibility that 4-cholesten-3-one inhibited ADC metastasis. Low-dose 4-cholesten-3-one significantly restrained ADC cells migration and invasion with little effects on cells viabilities. Further investigation showed that 4-cholesten-3-one promoted ROS generation, which transiently activated AMPKα1, increased HIF1α expression, reduced Bcl-2 expression and caused autophagy. AMPKα1 knockdown partly suppressed 4-cholesten-3-one-induced autophagy but, neither prevented 4-cholesten-3-one-induced upregulation of HIF1α or downregulation of Bcl-2. 4-cholesten-3-one-induced autophagy facilitated the release of HMGB1 from nuclei to cytoplasm, blocking nuclear translocation of HIF1α and activation of MMP2 and MMP9. Also, 4-cholesten-3-one induced time-dependent phosphorylation of caveolin-1, Akt and NF-κB. With increasing treatment time, 4-cholesten-3-one accelerated caveolin-1 internalization, but reduced the phosphorylation of Akt and NF-κB, and inhibited the expression of snail and twist. These data suggested that 4-cholesten-3-one could be a potential candidate for anti-metastasis of lung adenocarcinoma.

Promotion of tumour proliferation, migration and invasion by miR-92b in targeting RECK in osteosarcoma

MicroRNAs play important roles in the development of cancers. Although miR-92b has been reported to promote the tumorigenesis of some cancers, its role in osteosarcoma remains unknown. In the present study, we focused on the expression, function and mechanisms of miR-92b in osteosarcoma development. The miRNA miR-92b was up-regulated in osteosarcoma cell lines and tissues; miR-92b up-regulation correlated with poor prognosis in osteosarcoma. Overexpression of miR-92b promoted osteosarcoma cell proliferation, migration and invasion, which was abrogated by miR-92b inhibition. Reversion-inducing, cysteine-rich protein with kazal motifs (RECK) was identified as the direct and functional target of miR-92b in osteosarcoma. Importantly, restoring RECK expression abrogated increases in cell growth, motility and invasiveness induced by miR-92b RECK was down-regulated in osteosarcoma tissues, and its expression level negatively correlated with miR-92b Collectively, our results indicate that miR-92b acts as an oncogenic miRNA and may be a therapeutic target in osteosarcoma.

MiR-26b inhibits melanoma cell proliferation and enhances apoptosis by suppressing TRAF5-mediated MAPK activation

Alterations in microRNA-26b (miR-26b) expression have been shown to participate in various malignant tumor developments. However, the possible function of miR-26b in human melanoma cells remains unclarified. In this study, quantitative polymerase chain reaction was used to explore the expression profiles of miR-26b in melanoma cells. The effect of miR-26b on cell viability was determined by using MTT assays and colony formation assay. The apoptosis levels were evaluated by using Annexin V/fluorescein isothiocyanate (FITC) apoptosis detection kit and the apoptosis cells were confirmed by Transmission Electron Microscopy (TEM). Luciferase reporter plasmids were constructed to confirm direct targeting. Our study found that the expression of miR-26b was downregulated in human melanoma specimens. Overexpression of miR-26b significantly increased the anti-proliferative effects and apoptosis in A375 and B16F10 melanoma cells. In addition, luciferase gene reporter assays confirmed that TRAF5 was a direct target gene of miR-26b and the anti-tumor effect of miR-26b in melanoma cells was significantly counteracted by treatment with TRAF5 overexpression. Furthermore, the molecular mechanisms underlying the tumor suppressor of miR-26b in malignant melanomas may be due to the dephosphorylation of MAPK pathway caused by the decrease in TRAF5 expression when miR-26b is up-regulated in melanoma cells. These findings indicate that miR-26b might influence TRAF5-MAPK signaling pathways to facilitate the malignant progression of melanoma cells.