Analysis of miRNA-gene expression-genomic profiles reveals complex mechanisms of microRNA deregulation in osteosarcoma

The crosstalk between miRNAs and signaling pathways in human cancers: Potential therapeutic implications

MicroRNAs (miRNAs) are increasingly recognized as central players in the regulation of eukaryotic physiological processes. These small double stranded RNA molecules have emerged as pivotal regulators in the intricate network of cellular signaling pathways, playing significant roles in the development and progression of human cancers. The central theme in miRNA-mediated regulation of signaling pathways involves their ability to target and modulate the expression of pathway components. Aberrant expression of miRNAs can either promote or suppress key signaling events, influencing critical cellular processes such as proliferation, apoptosis, angiogenesis, and metastasis. For example, oncogenic miRNAs often promote cancer progression by targeting tumor suppressors or negative regulators of signaling pathways, thereby enhancing pathway activity. Conversely, tumor-suppressive miRNAs frequently inhibit oncogenic signaling by targeting key components within these pathways. This complex regulatory crosstalk underscores the significance of miRNAs as central players in shaping the signaling landscape of cancer cells. Furthermore, the therapeutic implications of targeting miRNAs in cancer are substantial. miRNAs can be manipulated to restore normal signaling pathway activity, offering a potential avenue for precision medicine. The development of miRNA-based therapeutics, including synthetic miRNA mimics and miRNA inhibitors, has shown promise in preclinical and clinical studies. These strategies aim to either enhance the activity of tumor-suppressive miRNAs or inhibit the function of oncogenic miRNAs, thereby restoring balanced signaling and impeding cancer progression. In conclusion, the crosstalk between miRNAs and signaling pathways in human cancers is a dynamic and influential aspect of cancer biology. Understanding this interplay provides valuable insights into cancer development and progression. Harnessing the therapeutic potential of miRNAs as regulators of signaling pathways opens up exciting opportunities for the development of innovative cancer treatments with the potential to improve patient outcomes. In this chapter, we provide an overview of the crosstalk between miRNAs and signaling pathways in the context of cancer and highlight the potential therapeutic implications of targeting this regulatory interplay.

Osteosarcoma in Pediatric and Adult Populations: Are Adults Just Big Kids?

Malignant bone tumors are commonly classified as pediatric or adolescent malignancies, and clinical trials for these diseases have generally focused on these populations. Of primary bone cancers, osteosarcoma is among the most common. Osteosarcoma has a bimodal age distribution, with the first peak occurring in patients from 10 to 14 years old, and the second peak occurring in patients older than 65, with about 25% of cases occurring in adults between 20 and 59 years old. Notably, adult osteosarcoma patients have worse outcomes than their pediatric counterparts. It remains unclear whether age itself is a poor prognostic factor, or if inherent differences in tumor biology exist between age groups. Despite these unknowns, current treatment strategies for adults are largely extrapolated from pediatric studies since the majority of clinical trials for osteosarcoma treatments are based on younger patient populations. In light of the different prognoses observed in pediatric and adult osteosarcoma, we summarize the current understanding of the molecular etiology of osteosarcoma and how it may differ between age groups, hypothesizing why adult patients have worse outcomes compared to children.

AP003352.1/miR-141-3p axis enhances the proliferation of osteosarcoma by LPAR3

Osteosarcoma (OS) is a highly malignant tumor with a poor prognosis and a growing incidence. LncRNAs and microRNAs control the occurrence and development process of osteosarcoma through ceRNA patterns. The LPAR3 gene is important in cancer cell proliferation, apoptosis and disease development. However, the regulatory mechanism of the ceRNA network through which LPAR3 participates in osteosarcoma has not been clarified. Herein, our study demonstrated that the AP003352.1/miR-141-3p axis drives LPAR3 expression to induce the malignant progression of osteosarcoma. First, the expression of LPAR3 is regulated by the changes in AP003352.1 and miR-141-3p. Similar to the ceRNA of miR-141-3p, AP003352.1 regulates the expression of LPAR3 through this mechanism. In addition, the regulation of AP003352.1 in malignant osteosarcoma progression depends to a certain degree on miR-141-3p. Importantly, the AP003352.1/miR-141-3p/LPAR3 axis can better serve as a multi-gene diagnostic marker for osteosarcoma. In conclusion, our research reveals a new ceRNA regulatory network, which provides a novel potential target for the diagnosis and treatment of osteosarcoma.

miR-137-LAPTM4B regulates cytoskeleton organization and cancer metastasis via the RhoA-LIMK-Cofilin pathway in osteosarcoma

Osteosarcoma (OS) is a rare malignant bone tumor but is one leading cause of cancer mortality in childhood and adolescence. Cancer metastasis accounts for the primary reason for treatment failure in OS patients. The dynamic organization of the cytoskeleton is fundamental for cell motility, migration, and cancer metastasis. Lysosome Associated Protein Transmembrane 4B (LAPTM4B) is an oncogene participating in various biological progress central to cancer biogenesis. However, the potential roles of LAPTM4B in OS and the related mechanisms remain unknown. Here, we established the elevated LAPTM4B expression in OS, and it is essential in regulating stress fiber organization through RhoA-LIMK-cofilin signaling pathway. In terms of mechanism, our data revealed that LAPTM4B promotes RhoA protein stability by suppressing the ubiquitin-mediated proteasome degradation pathway. Moreover, our data show that miR-137, rather than gene copy number and methylation status, contributes to the upregulation of LAPTM4B in OS. We report that miR-137 is capable of regulating stress fiber arrangement, OS cell migration, and metastasis via targeting LAPTM4B. Combining results from cells, patients' tissue samples, the animal model, and cancer databases, this study further suggests that the miR-137-LAPTM4B axis represents a clinically relevant pathway in OS progression and a viable target for novel therapeutics.

miRNAs as potential game-changers in bone diseases: Future medicinal and clinical uses

MicroRNAs (miRNAs), short, highly conserved non-coding RNA, influence gene expression by sequential mechanisms such as mRNA breakdown or translational repression. Many biological processes depend on these regulating substances, thus changes in their expression have an impact on the maintenance of cellular homeostasis and result in the emergence of a variety of diseases. Relevant studies have shown in recent years that miRNAs are involved in many stages of bone development and growth. Additionally, abnormal production of miRNA in bone tissues has been closely associated with the development of numerous bone disorders, such as osteonecrosis, bone cancer, and bone metastases. Many pathological processes, including bone loss, metastasis, the proliferation of osteosarcoma cells, and differentiation of osteoblasts and osteoclasts, are under the control of miRNAs. By bringing together the most up-to-date information on the clinical relevance of miRNAs in such diseases, this study hopes to further the study of the biological features of miRNAs in bone disorders and explore their potential as a therapeutic target.

Targeting Signaling Pathway by Curcumin in Osteosarcoma

The most prevalent primary bone malignancy among children and adolescents is osteosarcoma. The high mortality rate of osteosarcoma is due to lung metastasis. Despite the development of multi-agent chemotherapy and surgical resection, patients with osteosarcoma have a high metastasis rate and poor prognosis. Thus, it is necessary to identify novel therapeutic agents to improve the 5-year survival rate of these patients. Curcumin, a phytochemical compound derived from Curcuma longa, has been employed in treating several types of cancers through various mechanisms. Also, in vitro studies have demonstrated that curcumin could inhibit cell proliferation and induce apoptosis in osteosarcoma cells. Development in identifying signaling pathways involved in the pathogenesis of osteosarcoma has provided insight into finding new therapeutic targets for the treatment of this cancer. Targeting MAPK/ERK, PI3k/AKT, Wnt/β-catenin, Notch, and MircoRNA by curcumin has been evaluated to improve outcomes in patients with osteosarcoma. Although curcumin is a potent anti-cancer compound, it has rarely been studied in clinical settings due to its congenital properties such as hydrophobicity and poor bioavailability. In this review, we recapitulate and describe the effect of curcumin in regulating signaling pathways involved in osteosarcoma.

Integrated DNA Copy Number and Expression Profiling Identifies IGF1R as a Prognostic Biomarker in Pediatric Osteosarcoma

Osteosarcoma is a primary malignant bone tumor arising from bone-forming mesenchymal cells in children and adolescents. Despite efforts to understand the biology of the disease and identify novel therapeutics, the survival of osteosarcoma patients remains dismal. We have concurrently profiled the copy number and gene expression of 226 osteosarcoma samples as part of the Strategic Partnering to Evaluate Cancer Signatures (SPECS) initiative. Our results demonstrate the heterogeneous landscape of osteosarcoma in younger populations by showing the presence of genome-wide copy number abnormalities occurring both recurrently among samples and in a high frequency. Insulin growth factor receptor 1 (IGF1R) is a receptor tyrosine kinase which binds IGF1 and IGF2 to activate downstream pathways involved in cell apoptosis and proliferation. We identify prevalent amplification of IGF1R corresponding with increased gene expression in patients with poor survival outcomes. Our results substantiate previously tenuously associated copy number abnormalities identified in smaller datasets (13q34+, 20p13+, 4q35-, 20q13.33-), and indicate the significance of high fibroblast growth factor receptor 2 (FGFR2) expression in distinguishing patients with poor prognosis. FGFR2 is involved in cellular proliferation processes such as division, growth and angiogenesis. In summary, our findings demonstrate the prognostic significance of several genes associated with osteosarcoma pathogenesis.

Navigating the genomic instability mine field of osteosarcoma to better understand implications of non-coding RNAs

Osteosarcoma is one of the most genomically complex cancers and as result, it has been difficult to assign genomic aberrations that contribute to disease progression and patient outcome consistently across samples. One potential source for correlating osteosarcoma and genomic biomarkers is within the non-coding regions of RNA that are differentially expressed. However, it is unsurprising that a cancer classification that is fraught with genomic instability is likely to have numerous studies correlating non-coding RNA expression and function have been published on the subject. This review undertakes the formidable task of evaluating the published literature of noncoding RNAs in osteosarcoma. This is not the first review on this topic and will certainly not be the last. The review is organized with an introduction into osteosarcoma and the epigenetic control of gene expression before reviewing the molecular function and expression of long non-coding RNAs, circular RNAs, and short non-coding RNAs such as microRNAs, piwi RNAs, and short-interfering RNAs. The review concludes with a review of the literature and how the biology of non-coding RNAs can be used therapeutically to treat cancers, especially osteosarcoma. We conclude that non-coding RNA expression and function in osteosarcoma is equally complex to understanding the expression differences and function of coding RNA and proteins; however, with the added lens of both coding and non-coding genomic sequence, researchers can begin to identify the patterns that consistently associate with aggressive osteosarcoma.

miR-486-5p expression is regulated by DNA methylation in osteosarcoma

Background

Osteosarcoma is the most common primary malignant tumour of bone occurring in children and young adolescents and is characterised by complex genetic and epigenetic changes. The miRNA miR-486-5p has been shown to be downregulated in osteosarcoma and in cancer in general.

Results

To investigate if the mir-486 locus is epigenetically regulated, we integrated DNA methylation and miR-486-5p expression data using cohorts of osteosarcoma cell lines and patient samples. A CpG island in the promoter of the ANK1 host gene of mir-486 was shown to be highly methylated in osteosarcoma cell lines as determined by methylation-specific PCR and direct bisulfite sequencing. High methylation levels were seen for osteosarcoma patient samples, xenografts and cell lines based on quantitative methylation-specific PCR. 5-Aza-2′-deoxycytidine treatment of osteosarcoma cell lines caused induction of miR-486-5p and ANK1, indicating common epigenetic regulation in osteosarcoma cell lines. When overexpressed, miR-486-5p affected cell morphology.

Conclusions

miR-486-5p represents a highly cancer relevant, epigenetically regulated miRNA in osteosarcoma, and this knowledge contributes to the understanding of osteosarcoma biology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08346-6.

MiRNA-218 inhibits cell proliferation, migration and invasion by targeting Runt-related transcription factor 2 (Runx2) in human osteosarcoma cells

PURPOSE

The deregulation of miRNA-218 has been found in a number of cancers. Using miRNA-218 as a target for Runt-related transcription factor 2 (Runx2), we sought to understand the role of miRNA-218 in osteosarcoma (OS).

METHODS

The expression of miRNA-218 was detected in the OS tumor tissues and OS cells. The Runx2 expression level was evaluated in Saos-2, 143B, U2OS, and MG-63. miRNA-218 overexpressed U2OS cells were achieved by transfection with miRNA-218 mimics. The role of miRNA-218 in inhibiting OS tumorigenesis was explored by CCK8, colony formation, cell wound scratch and Transwell assay. TargetScan and dual-luciferase reporter assay identified the interaction between miRNA-218 and Runx2. The inhibitive effect of miRNA-218 on OS through targeting Runx2 was also evaluated.

RESULTS

MiRNA-218 levels were remarkably down-regulated in OS tumor tissues and cell lines. The overexpression of miRNA-218 suppressed U2OS cell development and metastasis. The target interaction between miRNA-218 and Runx2 was validated, and their expression showed a negative correlation in U2OS cells. The suppressed U2OS cell development and metastasis were remarkably reversed by Runx2 overexpression.

CONCLUSION

MiRNA-218 showed an inhibitive effect on the development and metastasis of osteosarcoma cell proliferation by targeting Runx2. Our findings may provide novel clues for OS treatment.

Verteporfin suppresses osteosarcoma progression by targeting the Hippo signaling pathway

Verteporfin (VP) is a specific inhibitor of yes-associated protein 1 (YAP1) that suppresses tumor progression by inhibiting YAP1 expression. The present study aimed to determine the inhibitory effect of VP on osteosarcoma and the underlying mechanism of its anticancer effects. Cell viability, cell cycle and apoptosis and cell migration and invasion were analyzed using the MTT assay, flow cytometry, wound healing assay and Transwell assay, respectively. Expressions of YAP1 and TEA domain transcription factor 1 (TEAD1) were measured using reverse transcription-quantitative PCR and western blotting, while their interaction was identified by the co-immunoprecipitation assay. In vivo mouse xenograft experiments were performed to evaluate the effect of VP on osteosarcoma growth. The results demonstrated that YAP1 and TEAD1 were highly expressed in osteosarcoma cells and tissues, whereas VP significantly downregulated the expression levels of YAP1 and TEAD1 in the osteosarcoma cell line Saos-2 compared with those in untreated control cells. In addition, compared with those in the control group, VP suppressed the viability, migration and invasion, induced cell cycle arrest in the G1 phase and promoted apoptosis in Saos-2 cells. In addition, VP inhibited mouse xenograft tumor growth in vivo compared with that observed in the control group. Notably, VP downregulated the levels of CYR61 expression in Saos-2 cells, whereas CYR61 overexpression mitigated the inhibitory effects of VP on osteosarcoma cells, as indicated by the increased viability and reduced apoptotic rates in Saos-2 cells overexpressing CYR61 compared with those in the control group. In summary, VP suppressed osteosarcoma by downregulating the expression of YAP1 and TEAD1. Additionally, CYR61 may mediate the effects of VP on osteosarcoma progression.

ARHGEF3 Associated with Invasion, Metastasis, and Proliferation in Human Osteosarcoma

Background

Osteosarcoma is a malignant bone tumor composed of mesenchymal cells producing osteoid and immature bone. This study is aimed at developing novel potential prognostic biomarkers and constructing a miRNA-mRNA network for progression in osteosarcoma.

Method

GSE70367 and GSE70414 were obtained in the Gene Expression Omnibus (GEO) database. GEO software and the GEO2R calculation method were used to analyze two gene profiles. The coexpression of differentially expressed miRNAs (DEMs) and genes (DEGs) was identified and searched for in the FunRich database for pathway and ontology analysis. Cytoscape was utilized to construct the mRNA-miRNA network. Survival analysis of identified miRNAs and mRNAs was performed by utilizing the Kaplan-Meier Plotter. Besides, expression levels of DEMs and target mRNAs were verified by performing quantitative real-time PCR (qRT-PCR) and Western blot (WB).

Results

Six differentially expressed microRNAs (DEMs) were identified, and 8 target genes were selected after screening. By using the KM Plotter software, miRNA-124 and ARHGEF3 were obviously associated with the overall survival of patients with osteosarcoma. Furthermore, ARHGEF3 was found downregulated in osteosarcoma cells by performing qRT-PCR and WB experiments. Results also showed that downregulated ARHGEF3 may associate with invasion, metastasis, and proliferation.

Conclusions

By using microarray and bioinformatics analysis, DEMs were selected, and a complete miRNA-mRNA network was constructed. ARHGEF3 may act as a therapeutic and prognostic target of osteosarcoma.

The EMT transcription factor ZEB1 blocks osteoblastic differentiation in bone development and osteosarcoma

Osteosarcoma is an often-fatal mesenchyme-derived malignancy in children and young adults. Overexpression of EMT-transcription factors (EMT-TFs) has been associated with poor clinical outcome. Here, we demonstrated that the EMT-TF ZEB1 is able to block osteoblastic differentiation in normal bone development as well as in osteosarcoma cells. Consequently, overexpression of ZEB1 in osteosarcoma characterizes poorly differentiated, highly metastatic subgroups and its depletion induces differentiation of osteosarcoma cells. Overexpression of ZEB1 in osteosarcoma is frequently associated with silencing of the imprinted DLK-DIO3 locus, which encodes for microRNAs targeting ZEB1. Epigenetic reactivation of this locus in osteosarcoma cells reduces ZEB1 expression, induces differentiation, and sensitizes to standard treatment, thus indicating therapeutic options for ZEB1-driven osteosarcomas. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

The role of microRNAs in the osteogenic and chondrogenic differentiation of mesenchymal stem cells and bone pathologies

Mesenchymal stem cells (MSCs) have been identified in many adult tissues. MSCs can regenerate through cell division or differentiate into adipocytes, osteoblasts and chondrocytes. As a result, MSCs have become an important source of cells in tissue engineering and regenerative medicine for bone tissue and cartilage. Several epigenetic factors are believed to play a role in MSCs differentiation. Among these, microRNA (miRNA) regulation is involved in the fine modulation of gene expression during osteogenic/chondrogenic differentiation. It has been reported that miRNAs are involved in bone homeostasis by modulating osteoblast gene expression. In addition, countless evidence has demonstrated that miRNAs dysregulation is involved in the development of osteoporosis and bone fractures. The deregulation of miRNAs expression has also been associated with several malignancies including bone cancer. In this context, bone-associated circulating miRNAs may be useful biomarkers for determining the predisposition, onset and development of osteoporosis, as well as in clinical applications to improve the diagnosis, follow-up and treatment of cancer and metastases. Overall, this review will provide an overview of how miRNAs activities participate in osteogenic/chondrogenic differentiation, while addressing the role of miRNA regulatory effects on target genes. Finally, the role of miRNAs in pathologies and therapies will be presented.

Up-regulation of LINC00619 promotes apoptosis and inhibits proliferation, migration and invasion while promoting apoptosis of osteosarcoma cells through inactivation of the HGF-mediated PI3K-Akt signalling pathway

This study is performed to evaluate the role of long noncoding RNA (lncRNA) LINC00619 in osteosarcoma through the PI3K-Akt signalling pathway by binding to HGF. Osteosarcoma and osteochondroma tissues from patients were collected. The relationship between lncRNA LINC00619 and HGF was proved by the dual-luciferase reporter gene assay. The expression patterns of lncRNA LINC00619 as well as the levels of proliferating cell nuclear antigen (PCNA), hepatocyte growth factor (HGF), phosphoinositide 3-kinase (PI3K), protein kinase B (Akt), Bax, Bcl-2, alkaline phosphatase (ALP), and osteopontin (OPN) were detected by RT-qPCR and Western blot analysis. In addition, MTT assay, flow cytometry, scratch test, and Transwell assay were performed to assess the cell proliferation, cell cycle distribution, apoptosis, cell migration, and invasion in each group, respectively. Osteosarcoma tissues presented with elevated positive expression rate of HGF, up-regulated expression levels of PCNA, HGF, PI3K, Akt, Bcl-2, ALP and OPN, and down-regulated expressions of Bax and LINC00619. HGF was verified as a target gene of lncRNA LINC00619. LINC00619 was found to down-regulate the expressions of PCNA, HGF, PI3K, Akt, Bcl-2, ALP, and OPN in osteosarcoma cells. Up-regulation of lncRNA LINC00619 decreased cell growth, migration intensity, and invasion ability, but enhanced the apoptosis rate of osteosarcoma cells. Our findings suggest that lncRNA LINC00619 inhibits proliferation, migration and invasion and improves apoptosis of osteosarcoma cells through the inhibition of the activation of the HGF-dependent PI3K-Akt signalling pathway.

PLOD1 Is a Prognostic Biomarker and Mediator of Proliferation and Invasion in Osteosarcoma

Objective

Osteosarcoma is the most common primary bone tumor and most frequently develops during adolescence. PLOD family was mainly involved in lysyl hydroxylation and rarely investigated in cancers, especially in osteosarcoma. The aim of this study was to investigate the expression pattern and oncogenic role of PLODs in osteosarcoma.

Methods

GEO datasets (GSE16088, GSE33382, and GSE16091) and validation cohort were used to analyze the expression pattern of PLODs in osteosarcoma. Kaplan-Meier survival analysis was used to explore the prognostic role of PLODs in patients with osteosarcoma. RNA interference of KRT19 was performed using small interfering RNA (siRNA) in MG-63 and U-2OS cells. The proliferation was detected using CCK8, clone formation assay, and EdU staining. Migration and invasion were determined using the transwell assay. Western blots and luciferase assays for β-catenin-T-cell factor protein/β-catenin-lymphoid enhancer factor- (β-catenin-TCF/LEF-) driven transcriptional activity.

Results

PLOD1 was upregulated in osteosarcoma tissues compared with control tissues both in public datasets and in in-house cohort. The expression of PLOD1 in osteosarcoma tissues was significantly associated with the status of distance metastasis and Enneking stage, while PLOD2 and PLOD3 expressed no difference between osteosarcoma and benign tissues and showed no correlation with tumor malignancy. Furthermore, Kaplan-Meier survival analysis revealed that patients with a higher level of PLOD1 had worse prognosis than those with a lower level of PLOD1. Downregulation of PLOD1 dramatically inhibited proliferation, migration, and invasion of MG-63 cells and U-2OS cells in vitro. Mechanistically, PLOD1 regulated β-catenin signaling pathway in osteosarcoma.

Conclusion

Our results indicated that PLOD1 promoted proliferation, migration, and invasion of osteosarcoma cells. PLOD1 was a novel prognostic marker, as well as a therapeutic target in osteosarcoma.

Molecular Biology of Osteosarcoma

Osteosarcoma (OS) is the most frequent primary bone cancer in children and adolescents and the third most frequent in adults. Many inherited germline mutations are responsible for syndromes that predispose to osteosarcomas including Li Fraumeni syndrome, retinoblastoma syndrome, Werner syndrome, Bloom syndrome or Diamond-Blackfan anemia. TP53 is the most frequently altered gene in osteosarcoma. Among other genes mutated in more than 10% of OS cases, c-Myc plays a role in OS development and promotes cell invasion by activating MEK-ERK pathways. Several genomic studies showed frequent alterations in the RB gene in pediatric OS patients. Osteosarcoma driver mutations have been reported in NOTCH1, FOS, NF2, WIF1, BRCA2, APC, PTCH1 and PRKAR1A genes. Some miRNAs such as miR-21, -34a, -143, -148a, -195a, -199a-3p and -382 regulate the pathogenic activity of MAPK and PI3K/Akt-signaling pathways in osteosarcoma. CD133+ osteosarcoma cells have been shown to exhibit stem-like gene expression and can be tumor-initiating cells and play a role in metastasis and development of drug resistance. Although currently osteosarcoma treatment is based on adriamycin chemoregimens and surgery, there are several potential targeted therapies in development. First of all, activity and safety of cabozantinib in osteosarcoma were studied, as well as sorafenib and pazopanib. Finally, novel bifunctional molecules, of potential imaging and osteosarcoma targeting applications may be used in the future.

Effects of radon on miR-34a-induced apoptosis in human bronchial epithelial BEAS-2B cells

Radon exposure is known to be the second most frequent cause followed by tobacco exposure for lung cancer development. In lung cancer development, microRNAs (miRNAs) play an important role in regulating various target genes associated with this disease. It is well-established that apoptosis is involved in the elimination of cancer cells. However, the mechanisms underlying chronic radon exposure induced miRNAs regulation attributed to result in carcinogenesis and subsequent activation of apoptosis is not completely understood. The aim of this study was thus to examine chronic low level radon exposure on lung miRNAs as a model for carcinogenesis induction and subsequent activation of apoptosis using human bronchial epithelial BEAS-2B cells. Quantitative real-time PCR (qRT-PCR) and flow cytometry were used to determine the miR-34a gene expression and apoptotic rate in BEAS-2B cells. Data demonstrated that chronic radon exposure up-regulated the expressions of miR-34a and enhanced cellular apoptosis in a time-dependent manner. Western blot analysis demonstrated that overexpression of the gene miR-34a enhanced apoptotic rate and elevated proapoptotic Bax protein expression accompanied by decreased protein expressions of antiapoptotic Bcl-2 and PARP-1. It is noteworthy that the apoptotic rate was elevated in BEAS-2B cells transfected with mi-R34a mimic but reduced in mi-R34a inhibitor-transfected cells. Evidence thus indicates that chronic exposure to radon produced up-regulation of miR-34a gene which subsequently enhanced apoptosis in BEAS-2B cells. The observed consequences following chronic radon exposure leading to carcinogenesis appear to involve activation of miR-34a gene.

MicroRNA-654-5p suppresses ovarian cancer development impacting on MYC, WNT and AKT pathways

Ovarian cancer is the most lethal gynecological malignancy due to the silent nature on its early onset and the rapid acquisition of drug resistance. Histologically heterogeneous, it includes several subtypes with different mutational landscapes, hampering the development of effective targeted therapies. Non-coding RNAs are emerging as potential new therapeutic targets in cancer. To search for a microRNA signature related to ovarian carcinomas and study its potential as effective targeted therapy, we examined the expression of 768 miRNA in a large collection of tumor samples and found miR-654-5p to be infraexpressed in ovarian serous carcinomas, the most common and aggressive type. Restoration of miR-654-5p levels reduced tumor cell viability in vitro and in vivo and impaired sphere formation capacity and viability of ovarian cancer patient-derived ascitic cells ex vivo. CDCP1 and PLAGL2 oncogenes were found to be the most relevant direct miR-654-5p targets and both genes convey in a molecular signature associated with key cancer pathways relevant to ovarian tumorigenesis, such as MYC, WNT and AKT pathways. Together, we unveiled the tumor suppressor function of miR-654-5p, suggesting that its restoration or co-targeting of CDCP1 and PLAGL2 may be an effective therapeutic approach for ovarian cancer.

Extracellular vesicles from osteosarcoma cell lines contain miRNAs associated with cell adhesion and apoptosis

Osteosarcoma is the most common primary bone tumor during childhood and adolescence. Several reports have presented data on serum biomarkers for osteosarcoma, but few reports have analyzed circulating microRNAs (miRNAs). In this study, we used next generation miRNA sequencing to examine miRNAs isolated from microvesicle-depleted extracellular vesicles (EVs) derived from six different human osteosarcoma or osteoblastic cell lines with different degrees of metastatic potential (i.e., SAOS2, MG63, HOS, 143B, U2OS and hFOB1.19). EVs from each cell line contain on average ~300 miRNAs, and ~70 of these miRNAs are present at very high levels (i.e., >1000 reads per million). The most prominent miRNAs are miR-21-5p, miR-143-3p, miR-148a-3p and 181a-5p, which are enriched between 3 and 100 fold and relatively abundant in EVs derived from metastatic SAOS2 cells compared to non-metastatic MG63 cells. Gene ontology analysis of predicted targets reveals that miRNAs present in EVs may regulate the metastatic potential of osteosarcoma cell lines by potentially inhibiting a network of genes (e.g., MAPK1, NRAS, FRS2, PRCKE, BCL2 and QKI) involved in apoptosis and/or cell adhesion. Our data indicate that osteosarcoma cell lines may selectively package miRNAs as molecular cargo of EVs that could function as paracrine agents to modulate the tumor micro-environment.

p16INK4a inhibits the proliferation of osteosarcoma cells through regulating the miR-146b-5p/TRAF6 pathway

Down-regulation of p16INK4a and miR-146b-5p contributes to tumorigenesis in osteosarcoma (OS). However, the correlation between p16INK4a and miR-146b-5p in OS proliferation remains largely unknown. In the present study, we demonstrated that miR-146b-5p expression was positively correlated with p16INK4a in OS, but inversely correlated with TNF receptor associated factor 6 (TRAF6) expression. Overexpression of miR-146b-5p dramatically suppressed OS cell proliferation. Mechanistically, we validated TRAF6 as a direct functional target of miR-146b-5p and found that miR-146b-5p overexpression significantly decreased the level of phosphorylated PI3k and Akt, which are the pivotal downstream effectors of TRAF6. Moreover, TRAF6 expression was positively correlated with Ki-67 but inversely correlated with miR-146b-5p expression. In OS cells, silencing of TRAF6 mimicked the anti-tumor effects of miR-146b-5p. p16INK4a is an important tumor suppressor gene frequently down-regulated in OS. We found that this inhibitory effect is associated with the suppression of the miR-146b-5p, and is mediated via up-regulating TRAF6 expression. Our findings identified p16INK4a and miR-146b-5p as tumor suppressors, and suggested p16INK4a, miR-146b-5p and TRAF6 as potential therapeutic candidates for malignant OS.

miR-183 modulated cell proliferation and apoptosis in ovarian cancer through the TGF-β/Smad4 signaling pathway

An increasing body of evidence has revealed that the aberrant expression of microRNAs (miRNAs/miRs) is involved in the development and progression of ovarian cancer (OC). miR-183 has been demonstrated to act as a tumor suppressor and oncogene in various types of human cancers. However, the biological role of miR-183 in OC still remains unclear. The aim of the present study was to investigate the role of miR-183 and evaluate its underlying mechanism in OC. In the present study, miR-183 was observed to be upregulated in OC tissues and cell lines as determined by reverse transcription-quantitative polymerase chain reaction. The effects of miR-183 on OC were further investigated via western blotting, MTT, wound healing, Transwell and immunofluorescence analyses. Downregulation of miR-183 markedly inhibited cell proliferation, migration and invasion, and promoted apoptosis in OC cells. Furthermore, it was initially confirmed that mothers against decapentaplegic homolog 4 (Smad4) was identified as an efficient target of miR-183 by luciferase activity assay. Finally, the results revealed that miR-183 directly regulated biological function via the transforming growth factor (TGF)-β/Smad4 signaling pathway in OC cells. In conclusion, the results of the present study suggested that miR-183 exerted tumor-promoting roles in OC, at least partially by regulating Smad4 via the TGF-β/Smad4 signaling pathway. Therefore, miR-183 may serve as a potential target for the diagnosis and prognosis of OC.

Construction of microRNA-messenger networks for human osteosarcoma

Osteosarcoma is the most common bone tumor in children and young adults. Although the microRNAs (miRNA) expression analyses of osteosarcoma have been performed previously, the construction of miRNA-messenger RNA (mRNA) networks for osteosarcoma is needed. This study aimed to identify osteosarcoma-related miRNAs through analyzing the microarray datasets and to construct the regulatory network of miRNA-mRNA for human osteosarcoma. The datasets were extracted from the Gene Expression Omnibus and the differentially expressed miRNAs were screened through the limma package in Bioconductor. Genes targeted by the differentially expressed miRNAs were screened out by using the Miranda, MirTarget2, PicTar, PITA, and TargetScan databases. The predicted target genes were further analyzed by Gene Ontology and pathway enrichment analysis and a regulatory network of differentially expressed miRNAs and their target osteosarcoma-associated genes was constructed. A total of 36 downregulated miRNAs and 182 upregulated miRNAs were identified in osteosarcoma samples compared with normal samples and 397 target genes for upregulated miRNAs and 222 target genes for downregulated miRNAs were obtained. The enriched pathways for target genes of differentially expressed miRNAs included transcriptional misregulation in cancer, the AMPK signaling pathway, and MAPK signaling pathway. In the regulatory network, has-miR-199a-5p targeted the highest number of genes and nemo-like kinase (NLK) was targeted by five miRNAs (hsa-miR-140-5p, hsa-miR-107, hsa-miR-324-5p, hsa-miR-199a-5p, and hsa-miR-28-5p). The has-miR-324-5p targets NLK, TGFB2, and PPARG. These miRNAs and their target genes may serve as potential therapeutic targets of osteosarcoma.

Knockdown of MALAT1 inhibits osteosarcoma progression via regulating the miR‑34a/cyclin D1 axis

Long non-coding (lnc)RNAs have been demonstrated to be involved in the development of various types of cancers, such as osteosarcoma (OS). Long non-coding (lnc) RNA metastasis associated lung adenocarcinoma transcript 1 (MALAT1) expression was reported to be highly expressed in OS and promoted the development of this disease; however, the underlying molecular mechanism by which MALAT1 promotes the progression of OS requires further investigation. In the present study, the expression of MALAT1 and miR-34a was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The abundance of cyclin D1 (CCND1) was detected by RT-qPCR and western blotting. Cell viability, migration and invasion were examined by MTT and Transwell assays. The interaction between miR-34a and MALAT1 or CCND1 was probed by a dual luciferase reporter assay and RNA immunoprecipitation. Xenograft tumor assay was performed to verify the roles of MALAT1 and miR-34a in tumor growth in vivo. The results demonstrated that MALAT1 and CCND1 mRNA expression levels were upregulated and miR-34a was downregulated in OS tissues and cells. Additionally, MALAT1 expression was correlated with tumor size, clinical stage and distant metastasis in patients with OS. In addition, MALAT1 promoted OS cell viability, invasion and migration, while MALAT1 silencing exhibited opposing effects. Moreover, MALAT1 functioned as a ceRNA to suppress miR-34a expression and in turn upregulate CCND1 in OS cells. Rescue experiments further demonstrated that MALAT1 knockdown partially reversed anti-miR-34a-mediated promotion on OS cell viability, migration and invasion; overexpression of CCND1 partially reversed the effects of MALAT1 silencing on OS progression. Furthermore, in vivo experiments also revealed that MALAT1 promoted OS tumor growth via miR-34a inhibition and upregulating the expression of CCND1. In conclusion, the present study suggested that MALAT1 exerted its oncogenic function in OS by regulating the miR-34a/CCND1 axis in OS, which may provide novel insight into the diagnosis and therapy for OS.

Genetic testing for high-grade osteosarcoma: a guide for future tailored treatments?

INTRODUCTION

Genetic characterization of osteosarcoma has evolved during the last decade, thanks to the integrated application of conventional and new candidate-driven and genome-wide technologies. Areas covered: This review provides an overview of the state of art in genetic testing applied to osteosarcoma, with particular regard to novel candidate genetic biomarkers that can be analyzed in tumor tissue and blood samples, which might be used to predict toxicity and prognosis, detect disease relapse, and improve patients' selection criteria for tailoring treatment. Expert commentary: Genetic testing based on modern technologies is expected to indicate new osteosarcoma-related prognostic markers and driver genes, which may highlight novel therapeutic targets and patients stratification biomarkers. The definition of tailored or targeted treatment approaches may improve outcome of patients with localized tumors and, even more, of those with metastatic disease, for whom progress in cure probability is highly warranted.

Variants in the 14q32 miRNA cluster are associated with osteosarcoma risk in the Spanish population

Association studies in osteosarcoma risk found significant results in intergenic regions, suggesting that regions which do not codify for proteins could play an important role. The deregulation of microRNAs (miRNAs) has been already associated with osteosarcoma. Consequently, genetic variants affecting miRNA function could be associated with risk. This study aimed to evaluate the involvement of all genetic variants in pre-miRNAs described so far in relationship to the risk of osteosarcoma. We analyzed a total of 213 genetic variants in 206 pre-miRNAs in two cohorts of osteosarcoma patients (n = 100) and their corresponding controls (n = 256) from Spanish and Slovenian populations, using Goldengate Veracode technology (Illumina). Four polymorphisms in pre-miRNAs at 14q32 miRNA cluster were associated with osteosarcoma risk in the Spanish population (rs12894467, rs61992671, rs58834075 and rs12879262). Pathway enrichment analysis including target genes of these miRNAs pointed out the WNT signaling pathways overrepresented. Moreover, different single nucleotide polymorphism (SNP) effects between the two populations included were observed, suggesting the existence of population differences. In conclusion, 14q32 miRNA cluster seems to be a hotspot for osteosarcoma susceptibility in the Spanish population, but not in the Slovenian, which supports the idea of the existence of population differences in developing this disease.

Long non-coding RNA ASBEL promotes osteosarcoma cell proliferation, migration, and invasion by regulating microRNA-21

Osteosarcoma is the most common malignant bone tumor in children and adolescents with high rate of incidence, high frequency of recurrence, and high degree of metastasis. This study aimed to investigate the effects of long noncoding RNA antisense ncRNA in the abundant in neuroepithelium area (ANA)/B-cell translocation gene 3 (BTG3) locus (lncRNA ASBEL) on the pathogenesis of osteosarcoma. The expression levels of ASBEL in human osteoblast cells and human osteosarcoma cells were evaluated using qRT-PCR. Effects of ASBEL knockdown on cell viability, migration, and invasion were detected using trypan blue exclusion assay, cell migration, and cell invasion assay, respectively. The regulatory effects of ASBEL on microRNA-21 (miR-21) were analyzed using qRT-PCR. The roles of miR-21 and protein phosphatase 2A (PP2A), the possible downstream factor of miR-21, in osteosarcoma cell proliferation, migration, and invasion were also explored. The results showed that ASBEL was highly expressed in osteosarcoma cells. Knockdown of ASBEL inhibited osteosarcoma cell viability, migration, and invasion, as well as the expression level of miR-21. PP2A was a direct target of miR-21, which participated in the effects of ASBEL and miR-21 on the activation of phosphatidylinositol 3-kinase/protein kinase 3/glycogen synthase kinase-3β (PI3K/AKT/GSK3β) and mitogen-activated protein kinase/extracellular regulated protein kinase (MEK/ERK) signaling pathways as well as the enhancement of osteosarcoma cell proliferation, migration, and invasion. In conclusion, we verified that ASBEL-miR-21-PP2A pathway might play critical regulatory effects on the pathogenesis of osteosarcoma and could be as the potential therapeutic target and biomarker for osteosarcoma treatment.

Clinical significance of circulating miR-25-3p as a novel diagnostic and prognostic biomarker in osteosarcoma

Background

Emerging evidence has suggested that circulating microRNAs (miRNAs) in body fluids have novel diagnostic and prognostic significance for patients with malignant diseases. The lack of useful biomarkers is a crucial problem of bone and soft tissue sarcomas; therefore, we investigated the circulating miRNA signature and its clinical relevance in osteosarcoma.

Methods

Global miRNA profiling was performed using patient serum collected from a discovery cohort of osteosarcoma patients and controls and cell culture media. The secretion of the detected miRNAs from osteosarcoma cells and clinical relevance of serum miRNA levels were evaluated using in vitro and in vivo models and a validation patient cohort.

Results

Discovery screening identified 236 serum miRNAs that were highly expressed in osteosarcoma patients compared with controls, and eight among these were also identified in the cell culture media. Upregulated expression levels of miR-17-5p and miR-25-3p were identified in osteosarcoma cells, and these were abundantly secreted into the culture media in tumor-derived exosomes. Serum miR-25-3p levels were significantly higher in osteosarcoma patients than in control individuals in the validation cohort, with favorable sensitivity and specificity compared with serum alkaline phosphatase. Furthermore, serum miR-25-3p levels at diagnosis were correlated with patient prognosis and reflected tumor burden in both in vivo models and patients; these associations were more sensitive than those of serum alkaline phosphatase.

Conclusions

Serum-based circulating miR-25-3p may serve as a non-invasive blood-based biomarker for tumor monitoring and prognostic prediction in osteosarcoma patients.

A support vector machine and a random forest classifier indicates a 15-miRNA set related to osteosarcoma recurrence

BACKGROUND

Osteosarcoma, which originates in the mesenchymal tissue, is the prevalent primary solid malignancy of the bone. It is of great importance to explore the mechanisms of metastasis and recurrence, which are two primary reasons accounting for the high death rate in osteosarcoma.

DATA AND METHODS

Three miRNA expression profiles related to osteosarcoma were downloaded from GEO DataSets. Differentially expressed miRNAs (DEmiRs) were screened using MetaDE.ES of the MetaDE package. A support vector machine (SVM) classifier was constructed using optimal miRNAs, and its prediction efficiency for recurrence was detected in independent datasets. Finally, a co-expression network was constructed based on the DEmiRs and their target genes.

RESULTS

In total, 78 significantly DEmiRs were screened. The SVM classifier constructed by 15 miRNAs could accurately classify 58 samples in 65 samples (89.2%) in the GSE39040 database, which was validated in another two databases, GSE39052 (84.62%, 22/26) and GSE79181 (91.3%, 21/23). Cox regression showed that four miRNAs, including hsa-miR-10b, hsa-miR-1227, hsa-miR-146b-3p, and hsa-miR-873, significantly correlated with tumor recurrence time. There were 137, 147, 145, and 77 target genes of the above four miRNAs, respectively, which were assigned to 17 gene ontology functionally annotated terms and 14 Kyoto Encyclopedia of Genes and Genomes pathways. Among them, the "Osteoclast differentiation" pathway contained a total of seven target genes and was analyzed further.

CONCLUSION

The 15-miRNAs-based SVM classifier provides a potential useful tool to predict the recurrence of osteosarcoma. Our results suggest the possible mechanisms of osteosarcoma metastasis and recurrence and provide fresh DEmiRs as potential biomarkers or therapeutic targets for osteosarcoma.

miRNA profiling identifies deregulated miRNAs associated with osteosarcoma development and time to metastasis in two large cohorts

Osteosarcoma (OS) is an aggressive bone tumor primarily affecting children and adolescents. The etiology of OS is not fully understood. Thus, there is a great need to obtain a better understanding of OS development and progression. Alterations in miRNA expression contribute to the required molecular alterations for neoplastic initiation and progression. This study is the first to investigate miRNA expression in OS in a large discovery and validation cohort comprising a total of 101 OS samples. We established the signature of altered miRNA expression in OS by profiling the expression level of 752 miRNAs in 23 OS samples using sensitive LNA-enhanced qPCR assays. The identified miRNA expression changes were correlated with gene expression in the same samples. Furthermore, miRNA expression changes were validated in a second independent cohort consisting of 78 OS samples. Analysis of 752 miRNAs in the discovery cohort led to the identification of 33 deregulated miRNAs in OS. Twenty-nine miRNAs were validated with statistical significance in the second cohort comprising 78 OS samples. miRNA/mRNA targets were determined, and 361 genes with an inverse expression of the target miRNA were identified. Both the miRNAs and the identified target genes were associated with multiple pathways related to cancer as well as bone cell biology, thereby correlating the deregulated miRNAs with OS tumorigenesis. An analysis of the prognostic value of the 29 miRNAs identified miR-221/miR-222 to be significantly associated with time to metastasis in both cohorts. This study contributes to a more profound understanding of OS tumorigenesis, by substantiating the importance of miRNA deregulation. We have identified and validated 29 deregulated miRNAs in the - to our knowledge - largest discovery and validation cohorts used so far for miRNA analyses in OS. Two of the miRNAs showed a promising potential as prognostic biomarkers for the aggressiveness of OS.

Identification of miRNA and genes involving in osteosarcoma by comprehensive analysis of microRNA and copy number variation data

The aim of the present study was to understand the molecular mechanisms of osteosarcoma by comprehensive analysis of microRNA (miRNA/miR) and copy number variation (CNV) microarray data. Microarray data (GSE65071 and GSE33153) were downloaded from the Gene Expression Omnibus. In GSE65071, differentially expressed miRNAs between the osteosarcoma and control groups were calculated by the Limma package. Target genes of differentially expressed miRNAs were identified by the starBase database. For GSE33153, PennCNV software was used to perform the copy number variation (CNV) analysis. Overlapping of the genes in CNV regions and the target genes of differentially expressed miRNAs were used to construct miRNA-gene regulatory network using the starBase database. A total of 149 differentially expressed miRNAs, including 13 downregulated and 136 upregulated, were identified. In the GSE33153 dataset, 987 CNV regions involving in 3,635 genes were identified. In total, 761 overlapping genes in 987 CNV regions and in the genes in 7,313 miRNA-gene pairs were obtained. miRNAs (hsa-miR-27a-3p, hsa-miR-124-3p, hsa-miR-9-5p, hsa-miR-182-5p, hsa-miR-26a-5p) and the genes [Fibroblast growth factor receptor substrate 2 (FRS2), coronin 1C (CORO1C), forkhead box P1 (FOXP1), cytoplasmic polyadenylation element binding protein 4 (CPEB4) and glucocorticoid induced 1 (GLCCI1)] with the highest degrees of association with osteosarcoma development were identified. Hsa-miR-27a-3p, hsa-miR-9-5p, hsa-miR-182-5p, FRS2, CORO1C, FOXP1 and CPEB4 may be involved in osteosarcoma pathogenesis, and development.

miR-187 inhibits tumor growth and invasion by directly targeting MAPK12 in osteosarcoma

MicroRNAs (miRNAs/miRs) play crucial roles in cancer development and progression. The purposes of this study were to investigate the role of miR-187 in osteosarcoma and clarify the regulation of MAPK12 by miR-187. Quantitative polymerase chain reaction was used to examine miR-187 expression in osteosarcoma tissues and cell lines. The clinicopathological significance of miR-187 downregulation was further analyzed. Transwell migration and invasion assays were performed. A luciferase reporter assay was conducted to confirm the target gene of miR-187, and the results were validated in cervical cancer tissues and cell lines. MiR-187 was significantly decreased in clinical tissues and osteosarcoma cell lines. The low miR-187 level was significantly correlated with stage, node metastasis, and deep stromal invasion. Upregulation of miR-187 suppressed cell migration and invasion in vitro. MAPK12 was verified as a direct target of miR-187, which was further confirmed by the inverse expression of miR-187 and MAPK12 in patients' specimens. The newly identified miR-187/MAPK12 pathway provides an insight into osteosarcoma metastasis and may represent a novel therapeutic target.

Tumor suppressor microRNA-34a inhibits cell migration and invasion by targeting MMP-2/MMP-9/FNDC3B in esophageal squamous cell carcinoma

MicroRNAs (miRNAs) are a large family of small, non-coding RNAs that play a pivotal role in tumorigenesis. miR‑34a, which is a member of the miR-34 family, is a downstream target of p53. Increasing evidence shows that miR-34a dysregulation may contribute to tumor development and progression in numerous cancers, including esophageal squamous cell carcinoma (ESCC). However, the mechanism of miR-34a in the regulation of ESCC cells need to be further elucidated because of the complex regulative network of miRNAs. The miR-34a expression in ESCC samples has been confirmed using quantitative reverse transcription polymerase chain reaction. The effects of miR-34a on cell migration and invasion were examined in ESCC cell lines using wound healing and Transwell assays, respectively. The effects of miR-34a on matrix metalloproteinase (MMP)-2 and -9 and fibronectin type III domain containing 3B (FNDC3B) expression levels were detected by luciferase reporter assays and western blot analysis. Quantitative polymerase chain reaction revealed that the miR‑34a expression is significantly downregulated in the ESCC tissues compared to that in the adjacent normal tissues. miR-34a overexpression was significantly suppressed migration and invasion in the ESCC cells and simultaneously inhibited the MMP-2, MMP-9 and FNDC3B expression levels by targeting the coding and 3'-untranslated regions, respectively. The findings indicated that microRNA‑34a suppresses cell migration and invasion by targeting MMP-2, MMP-9, and FNDC3B in ESCC.

MicroRNA-379 inhibits the proliferation, migration and invasion of human osteosarcoma cells by targetting EIF4G2

Osteosarcoma (OS) is an aggressive malignant mesenchymal neoplasm amongst adolescents. The aim of the present study was to explore the various modes of action that miR-379 has on the proliferation, migration, and invasion of human OS cells. miR-379 achieves this by targetting eukaryotic initiation factor 4GII (EIF4G2). Human OS cell lines U2OS and MG-63 were selected and assigned into blank, miR-379 mimics, miR-379 mimic negative control (NC), miR-379 inhibitors, miR-379 inhibitor NC, EIF4G2 shRNA, control shRNA, and miR-379 inhibitor + EIF4G2 shRNA group. The miR-379 expression and EIF4G2 mRNA expression were detected utilising quantitative real-time PCR (qRT-PCR) and the EIF4G2 protein expression using Western blotting. MTT assay, scratch test, Transwell assay, and flow cytometry were performed to determine the proliferation, migration, invasion, and cell cycle, respectively. In comparison with the miR-379 mimic NC group, the miR-379 mimics group had decreased EIF4G2 expression; the miR-379 inhibitors group indicated an increased EIF4G2 expression. Compared with the control shRNA group, the EIF4G2 expression was lower in the EIF4G2 shRNA group and the miR-379 expression was dropped in the miR-379 inhibitor + EIF4G2 shRNA group. The proliferation, migration, and invasion abilities of OS cells were reduced in the miR-379 mimics and EIF4G2 shRNA groups. The percentage of OS cells at the G₀/G₁ stage was increased, and the percentage at the S-stage was decreased in the miR-379 mimics and EIF4G2 shRNA groups. miR-379 may inhibit the proliferation, migration and invasion of OS cells through the down-regulation of EIF4G2.

Hypoxia-related microRNA-210 is a diagnostic marker for discriminating osteoblastoma and osteosarcoma

Osteoblastoma is a benign bone tumor that can often be difficult to distinguish from malignant osteosarcoma. Because misdiagnosis can result in unfavorable clinical outcomes, we have investigated microRNAs as potential diagnostic biomarkers for distinguishing between these two tumor types. Next generation RNA sequencing was used as an expression screen to evaluate >2,000 microRNAs present in tissue derived from rare formalin fixed paraffin embedded (FFPE) archival tumor specimens. MicroRNAs displaying the greatest ability to discriminate between these two tumors were validated on an independent tumor set, using qPCR assays. Initial screening by RNA-seq identified four microRNA biomarker candidates. Expression of three miRNAs (miR-451a, miR-144-3p, miR-486-5p) was higher in osteoblastoma, while the miR-210 was elevated in osteosarcoma. Validation of these microRNAs on an independent data set of 22 tumor specimens by qPCR revealed that miR-210 is the most discriminating marker. This microRNA displays low levels of expression across all of the osteoblastoma specimens and robust expression in the majority of the osteosarcoma specimens. Application of these biomarkers to a clinical test case showed that these microRNA biomarkers permit re-classification of a misdiagnosed FFPE tumor sample from osteoblastoma to osteosarcoma. Our findings establish that the hypoxia-related miR-210 is a discriminatory marker that distinguishes between osteoblastoma and osteosarcoma. This discovery provides a complementary molecular approach to support pathological classification of two diagnostically challenging musculoskeletal tumors. Because miR-210 is linked to the cellular hypoxia response, its detection may be linked to well-established pro-angiogenic and metastatic roles of hypoxia in osteosarcomas and other tumor cell types. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1137-1146, 2017.

Downregulation of calbindin 1, a calcium-binding protein, reduces the proliferation of osteosarcoma cells

Osteosarcoma is the most common type of primary malignant bone tumor and has a high propensity to metastasize to the lungs and bones. Calbindin 1 (CALB1) is a constituent Ca2+ binding protein, which can prevent apoptotic death in several cell types induced through various pro-apoptotic signaling pathways. To investigate whether CALB1 is implicated in the tumor growth of human osteosarcoma, two different short hairpin RNAs (shRNAs) against CALB1 were used for CALB1-knockdown in osteosarcoma U2OS cells. The U2OS cells were divided into three groups: Two groups with CALB1 knockdown (CALB1-shRNA 1 and CALB1-shRNA 2) and one control group (Con-shRNA). Reverse transcription-quantitative polymerase chain reaction and western blot analysis confirmed that the CALB1-shRNA 1- and 2-infected cells exhibited significantly lower levels of CALB1 gene and protein expression compared with the Con-shRNA group. The proliferation and colony formation abilities were significantly inhibited in CALB1-deficient U2OS cells compared with the control, as measured using an MTT assay and crystal violet staining. Flow cytometry revealed that the number of CALB1-shRNA 2-injected cells was increased in the G0/G1 and G2/M phases, but decreased in the S phase, compared with the control group. The assessment of apoptosis and necrosis using Annexin V/7-aminoactinomycin D demonstrated that there was a significantly higher percentage of necrotic, early apoptotic, and late apoptotic cells, but a significantly lower percentage of viable cells in U2OS cells with CALB1-knockdown compared with the control group. In conclusion, CALB1 contributes to protecting osteosarcoma cells from apoptosis and provides a potential novel target for gene therapy to treat patients with osteosarcoma.

Elevated expression of microRNA-19a predicts a poor prognosis in patients with osteosarcoma

MicroRNA (miR)-19a, a member of the miR-17-92 cluster, functions as an oncomiRNA in multiple kinds of cancers. However, its involvement in human osteosarcomas remains unclear. In this study, to analyze the expression pattern of miR-19a and to investigate its clinical implication in human osteosarcomas, quantitative reverse-transcription polymerase chain reaction was performed to detect expression levels of miR-19a in 166 self-pairs of osteosarcoma and noncancerous bone tissues. Associations between miR-19a expression and various clinicopathological parameters and patients' prognosis of osteosarcomas were further evaluated. As a results, miR-19a expression in osteosarcoma tissues was significantly higher than that in corresponding noncancerous bone tissues (P<0.001). Osteosarcoma patients with high miR-19a expression more frequently had large tumor size (P=0.03), advanced clinical stage (P=0.01), positive distant metastasis (P=0.008) and poor response to chemotherapy (P=0.01) than those with low miR-19a expression. Additionally, kaplan-Meier analysis showed that both overall and disease-free survivals of osteosarcoma patients with high miR-19a expression were shorter than those with low miR-19a expression (both P<0.001). Further multivariate analysis identified miR-19a expression as an independent prognostic factor for both overall (P=0.001) and disease-free (P=0.006) survivals. In conclusion, the aberrant expression of miR-19a may play a crucial role in development and progression of human osteosarcomas. MiR-19a may act as a novel prognostic marker for patients with this malignancy.

miR-125b and miR-100 Are Predictive Biomarkers of Response to Induction Chemotherapy in Osteosarcoma

Osteosarcoma is the most common primary malignancy in bone. Patients who respond poorly to induction chemotherapy are at higher risk of adverse prognosis. The molecular basis for such poor prognosis remains unclear. We investigated miRNA expression in eight open biopsy samples to identify miRNAs predictive of response to induction chemotherapy and thus maybe used for risk stratification therapy. The samples were obtained from four patients with inferior necrosis (Huvos I/II) and four patients with superior necrosis (Huvos III/IV) following induction chemotherapy. We found six miRNAs, including miR-125b and miR-100, that were differentially expressed > 2-fold (p < 0.05) in patients who respond poorly to treatment. The association between poor prognosis and the abundance of miR-125b and miR-100 was confirmed by quantitative reverse transcriptase-polymerase chain reaction in 20 additional osteosarcoma patients. Accordingly, overexpression of miR-125b and miR-100 in three osteosarcoma cell lines enhanced cell proliferation, invasiveness, and resistance to chemotherapeutic drugs such as methotrexate, doxorubicin, and cisplatin. In addition, overexpression of miR-125b blocked the ability of these chemotherapy agents to induce apoptosis. As open biopsy is routinely performed to diagnose osteosarcoma, levels of miR-125b and miR-100 in these samples may be used as basis for risk stratification therapy.

miR-574-3p acts as a tumor promoter in osteosarcoma by targeting SMAD4 signaling pathway

Human osteosarcoma is the most common primary bone malignancy sarcoma that affects primarily children and people <20 years old. In the present study, it was demonstrated that miR-574-3p was downregulated in human osteosarcoma U2OS, SAOS and MG63 cells lines as well as in osteosarcoma tissue compared with the normal tissues. Downregulation of miR-574-3p by antisense miR-574-3p, inhibited cell growth and induced cell apoptosis. Overexpression of miR-574-3p by transfection with miR-574-3p mimics promoted the growth of U2OS cells. The present study then identified mothers against decapentaplegic homolog 4 (SMAD4) as a target of miR-574-3p and SMAD4 was suppressed in miR-574-3p transfected cells. Overexpression of SMAD4 could rescue the promoting effects of miR-574-3p on cancer cell growth. In conclusion, miR-574-3p exerts tumor-promoting roles by targeting the tumor-suppressing gene SMAD4 and its downstream signaling in human osteosarcoma, which provides a novel target for the treatment.

MiR-9 is overexpressed in spontaneous canine osteosarcoma and promotes a metastatic phenotype including invasion and migration in osteoblasts and osteosarcoma cell lines

Background

MicroRNAs (miRNAs) regulate the expression of networks of genes and their dysregulation is well documented in human malignancies; however, limited information exists regarding the impact of miRNAs on the development and progression of osteosarcoma (OS). Canine OS exhibits clinical and molecular features that closely resemble the corresponding human disease and it is considered a well-established spontaneous animal model to study OS biology. The purpose of this study was to investigate miRNA dysregulation in canine OS.

Methods

We evaluated miRNA expression in primary canine OS tumors and normal canine osteoblast cells using the nanoString nCounter system. Quantitative PCR was used to validate the nanoString findings and to assess miR-9 expression in canine OS tumors, OS cell lines, and normal osteoblasts. Canine osteoblasts and OS cell lines were stably transduced with pre-miR-9 or anti-miR-9 lentiviral constructs to determine the consequences of miR-9 on cell proliferation, apoptosis, invasion and migration. Proteomic and gene expression profiling of normal canine osteoblasts with enforced miR-9 expression was performed using 2D-DIGE/tandem mass spectrometry and RNA sequencing and changes in protein and mRNA expression were validated with Western blotting and quantitative PCR. OS cell lines were transduced with gelsolin (GSN) shRNAs to investigate the impact of GSN knockdown on OS cell invasion.

Results

We identified a unique miRNA signature associated with primary canine OS and identified miR-9 as being significantly overexpressed in canine OS tumors and cell lines compared to normal osteoblasts. Additionally, high miR-9 expression was demonstrated in tumor-specific tissue obtained from primary OS tumors. In normal osteoblasts and OS cell lines transduced with miR-9 lentivirus, enhanced invasion and migration were observed, but miR-9 did not affect cell proliferation or apoptosis. Proteomic and transcriptional profiling of normal canine osteoblasts overexpressing miR-9 identified alterations in numerous genes, including upregulation of GSN, an actin filament-severing protein involved in cytoskeletal remodeling. Lastly, stable downregulation of miR-9 in OS cell lines reduced GSN expression with a concomitant decrease in cell invasion and migration; concordantly, cells transduced with GSN shRNA demonstrated decreased invasive properties.

Conclusions

Our findings demonstrate that miR-9 promotes a metastatic phenotype in normal canine osteoblasts and malignant OS cell lines, and that this is mediated in part by enhanced GSN expression. As such, miR-9 represents a novel target for therapeutic intervention in OS.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2837-5) contains supplementary material, which is available to authorized users.

MicroRNA-137 is downregulated in human osteosarcoma and regulates cell proliferation and migration through targeting FXYD6

BACKGROUND

In this work, we investigated the functional role of microRNA 137 (miR-137) in regulating osteosarcoma both in vitro and in vivo.

METHODS

Quantitative RT-PCR was used to examine the gene expressions of miR-137 in osteosarcoma cell lines and osteosarcoma tumors. 143B and Saos-2 cells were infected with lentivirus expressing miR-137 mimics (miR-137-mimic) to ectopically upregulate miR-137. In vitro cancer proliferation and migration were examined by MTT assay and transwell assay, respectively. Viral infected Saos-2 cells were also subcutaneously inoculated into null mice to evaluate the effect of miR-137 upregulation on in vivo tumor growth. The interaction between miR-137 and its downstream target, FXYD6, was evaluated by dual-luciferase reporter assay and quantitative real-time PCR. FXYD6 was then subsequently upregulated in osteosarcoma cells to evaluate its effect on miR-137 regulation in osteosarcoma.

RESULTS

We found that miR-137 was significantly downregulated in both osteosarcoma cell lines and osteosarcoma tumors. Lentiviral infection of miR-137-mimic upregulated miR-137 gene expression, reduced in vitro proliferation and migration and inhibited in vivo osteosarcoma tumor growth. FXYD6 was verified to be directly interacting with miR-137, and its subsequent upregulation reversed the inhibitory effect of miR-137 upregulation in osteosarcoma.

CONCLUSION

We revealed novel functional role of miR-137 in osteosarcoma regulation, likely through FXYD6 binding.

MiR-24-BIM-Smac/DIABLO axis controls the sensitivity to doxorubicin treatment in osteosarcoma

Emerging evidence shows that microRNAs (miRNAs) act as critical regulators in the progression and chemoresistance of multiple tumors, including osteosarcoma (OS). In this study, we found that the level of miR-24 was increased in OS patients’ serum, tumor tissues and OS cell lines. Furthermore, we found that knockdown of miR-24 by its specific inhibitors significantly increased the therapeutic effect of doxorubicin (DOX) on OS cell lines (MG-63 and HOS). Moreover, miR-24 inhibitors resensitized the doxorubicin-resistant MG-63 cells (MG-63/R) and HOS cells (HOS/R) to DOX. As the gene of Bcl-2 interacting mediator of cell death (BIM) was proved to be a target of miR-24 in MG-63/R cells, we further observed that the miR-24 inhibitors promoted the DOX-induced apoptosis via mitochondrial pathway. In addition, results of immunoprecipitation showed the release of second mitochondria derived activator of caspase/ direct IAP binding protein with low pI (Smac/DIABLO) abolished the biological activity of X-linked inhibitor of apoptosis protein (XIAP) by binding with it, which subsequently induced the activation of caspase 9, 7 and 3. In summary, those results strongly suggest that the miR-24-BIM-Smac/DIABLO axis might be a novel target for the treatment of OS.

miRNAs Related to Skeletal Diseases

miRNAs as non-coding, short, double-stranded RNA segments are important for cellular biological functions, such as proliferation, differentiation, and apoptosis. miRNAs mainly contribute to the inhibition of important protein translations through their cleavage or direct repression of target messenger RNAs expressions. In the last decade, miRNAs got in the focus of interest with new publications on miRNAs in the context of different diseases. For many types of cancer or myocardial damage, typical signatures of local or systemically circulating miRNAs have already been described. However, little is known about miRNA expressions and their molecular effect in skeletal diseases. An overview of published studies reporting miRNAs detection linked with skeletal diseases was conducted. All regulated miRNAs were summarized and their molecular interactions were illustrated. This review summarizes the involvement and interaction of miRNAs in different skeletal diseases. Thereby, 59 miRNAs were described to be deregulated in tissue, cells, or in the circulation of osteoarthritis (OA), 23 miRNAs deregulated in osteoporosis, and 107 miRNAs deregulated in osteosarcoma (OS). The molecular influences of miRNAs regarding OA, osteoporosis, and OS were illustrated. Specific miRNA signatures for skeletal diseases are described in the literature. Some overlapped, but also unique ones for each disease exist. These miRNAs may present useful targets for the development of new therapeutic approaches and are candidates for diagnostic evaluations.

MiR-125b Functions as a Tumor Suppressor and Enhances Chemosensitivity to Cisplatin in Osteosarcoma

MicroRNAs are highly conserved noncoding RNA that negatively modulate protein expression at a posttranscriptional and/or translational level and are deeply involved in the pathogenesis of several types of cancers. To date, the potential microRNAs regulating the growth and progression of osteosarcoma are not fully identified yet. Previous reports have shown differentially expressed miR-125b in osteosarcoma. However, the role of miR-125b in human osteosarcoma has not been totally illuminated. In this study, we have shown that miR-125b was downregulated in human osteosarcoma tissues compared to the adjacent tissues and effects as a tumor suppressor in vitro. We found that stable overexpression of miR-125b in osteosarcoma cell lines U2OS and MG-63 inhibited cell proliferation, migration, and invasion. Our data also verified that Bcl-2 is the target of miR-125b. Meanwhile, we showed that Bcl-2 was inversely correlated with miR-125b in osteosarcoma tissues. More importantly, we proved that miR-125b increased the chemosensitivity of osteosarcoma cell lines to cisplatin by targeting Bcl-2. In conclusion, our data demonstrate that miR-125b is a tumor suppressor and support its potential application for the treatment of osteosarcoma in the future.

Integrated bioinformatics analysis of miRNA expression in osteosarcoma

The expression of miRNA influencing the pathogenesis of OS have been reported previously, however, different samples selection and sequencing platforms made obvious differences in miRNA expression analysis. We aim to identify reliable prognostic and treatment biomarkers for OS by systematic analysis of miRNAs expression data sets from biased data set. Seven miRNA data sets were selected from corresponding articles. Collectively, two miRNAs, hsa-miR-19-3p and hsa-miR106b-3p, and transcription factor SIX3 were identified and may be reliable markers for prognostic and treatment of osteosarcoma.

Increased cathepsin D protein expression is a biomarker for osteosarcomas, pulmonary metastases and other bone malignancies

Cancer proteomics provide a powerful approach to identify biomarkers for personalized medicine. Particularly, biomarkers for early detection, prognosis and therapeutic intervention of bone cancers, especially osteosarcomas, are missing. Initially, we compared two-dimensional gel electrophoresis (2-DE)-based protein expression pattern between cell lines of fetal osteoblasts, osteosarcoma and pulmonary metastasis derived from osteosarcoma. Two independent statistical analyses by means of PDQuest® and SameSpot® software revealed a common set of 34 differentially expressed protein spots (p < 0.05). 17 Proteins were identified by mass spectrometry and subjected to Ingenuity Pathway Analysis resulting in one high-ranked network associated with Gene Expression, Cell Death and Cell-To-Cell Signaling and Interaction. Ran/TC4-binding protein (RANBP1) and Cathepsin D (CTSD) were further validated by Western Blot in cell lines while the latter one showed higher expression differences also in cytospins and in clinical samples using tissue microarrays comprising osteosarcomas, metastases, other bone malignancies, and control tissues. The results show that protein expression patterns distinguish fetal osteoblasts from osteosarcomas, pulmonary metastases, and other bone diseases with relevant sensitivities between 55.56% and 100% at ≥87.50% specificity. Particularly, CTSD was validated in clinical material and could thus serve as a new biomarker for bone malignancies and potentially guide individualized treatment regimes.