MicroRNAs and Potential Targets in Osteosarcoma: Review

LncRNA SNHG25 Predicts Poor Prognosis and Promotes Progression in Osteosarcoma via the miR-497-5p/SOX4 Axis

BACKGROUND

Osteosarcoma is a disease that primarily affects adolescents with skeletal immaturity. LncRNAs are abnormally expressed and correlated with osteosarcoma patients' prognosis. We identified aberrant expression of LncRNA SNHG25 (small nucleolar RNA host gene 25) in osteosarcoma and analyzed the molecular mechanisms by which it regulates osteosarcoma progression.

METHODS

The expression levels of SNHG25 in tumour specimens and cells were measured by RTqPCR. Loss-of-function assays were conducted to investigate the functional role of SNHG25 in vitro and in vivo. Bioinformatic predictions, dual-luciferase reporter assays, and western blotting were performed to explore the possible underlying mechanisms.

RESULTS

SNHG25 was highly expressed in osteosarcoma cells and tissues. The Kaplan-Meier curve showed that the survival rate of patients with high SNHG25 expression was significantly lower than those with low SNHG25 expression. Functional studies have indicated that inhibition of SNHG25 suppresses cell proliferation, migration, and invasion, while promoting apoptosis. SNHG25 knockdown suppresses osteosarcoma tumour growth in vivo. SNHG25 functions as a sponge for miR-497-5p in osteosarcoma cells. The level of SNHG25 was negatively correlated with that of miR-497-5p. The proliferation, invasion, and migration of osteosarcoma cells were restored by transfection of the miR-497-5p inhibitor in the SNHG25 knockdown group.

CONCLUSION

SNHG25 was determined to function as an oncogene by promoting osteosarcoma cell proliferation, invasion, and migration through the miR-497-5p/SOX4 axis. Upregulation of SNHG25 expression indicated poor prognosis in patients with osteosarcoma, which showed that SNHG25 may serve as a potential therapeutic target and prognostic biomarker in osteosarcoma.

circ_0002060 Enhances Doxorubicin Resistance in Osteosarcoma by Regulating the miR-198/ABCB1 Axis

Background: Osteosarcoma (OS) is a common, aggressive primary sarcoma of bone. Drug resistance is a huge obstacle to chemotherapy for cancer. This study aimed to investigate the role and mechanism of circ_0002060 in OS resistance to doxorubicin (DOX). Methods: The levels of circ_0002060, miR-198, and ATP-binding cassette subfamily B member 1 (ABCB1) in OS tissues and DOX-resistant OS cells were measured by quantitative real-time polymerase chain reaction or Western blot assay. Kaplan-Meier analysis was performed to determine the relationship between circ_0002060 expression in OS tissues and overall survival of OS patients. The half-inhibitory concentration (IC50) of DOX was calculated using the Cell Counting Kit-8 (CCK-8) assay. Proliferation and apoptosis of DOX-resistant OS cells were assessed by colony formation assay and flow cytometry. The levels of apoptosis-related proteins in DOX-resistant OS cells were measured by Western blot assay. Xenograft assay was utilized to analyze the effect of circ_0002060 on DOX resistance in vivo. The interactions among circ_0002060, miR-198, and ABCB1 in DOX-resistant OS cells were confirmed by dual-luciferase reporter assay, RNA immunoprecipitation assay, or RNA pull-down assay. Results: circ_0002060 and ABCB1 were upregulated, while miR-198 was downregulated in OS tissues and DOX-resistant OS cells. circ_0002060 silencing reduced DOX resistance in vitro and in vivo. Moreover, circ_0002060 enhanced DOX resistance by sponging miR-198. Besides, miR-198 decreased DOX resistance by binding to ABCB1. In addition, circ_0002060 sponged miR-198 to upregulate ABCB1 expression. Conclusions: circ_0002060 promoted DOX resistance and OS progression by regulating the miR-198/ABCB1 axis, suggesting that circ_0002060 might be a promising biomarker for OS therapy.

MiR-4270 acts as a tumor suppressor by directly targeting Bcl-xL in human osteosarcoma cells

Chondrosarcomas and osteosarcomas are malignant bone tumors with a poor prognosis when unresectable or metastasized. Moreover, radiotherapy and chemotherapy could be ineffective. MiRNAs represent an alternative therapeutic approach. Based on high-throughput functional screening, we identified four miRNAs with a potential antiproliferative effect on SW1353 chondrosarcoma cells. Individual functional validations were then performed in SW1353 cells, as well as in three osteosarcoma cell lines. The antiproliferative and cytotoxic effects of miRNAs were evaluated in comparison with a positive control, miR-342-5p. The cytotoxic effect of four selected miRNAs was not confirmed on SW1353 cells, but we unambiguously revealed that miR-4270 had a potent cytotoxic effect on HOS and MG-63 osteosarcoma cell lines, but not on SaOS-2 cell line. Furthermore, like miR-342-5p, miR-4270 induced apoptosis in these two cell lines. In addition, we provided the first report of Bcl-xL as a direct target of miR-4270. MiR-4270 also decreased the expression of the anti-apoptotic protein Mcl-1, and increased the expression of the pro-apoptotic protein Bak. Our findings demonstrated that miR-4270 has tumor suppressive activity in osteosarcoma cells, particularly through Bcl-xL downregulation.

Palmitic acid-induced microRNA-143-5p expression promotes the epithelial-mesenchymal transition of retinal pigment epithelium via negatively regulating JDP2

BACKGROUND

The epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells is the most crucial step in the etiopathogenesis of proliferative vitreoretinopathy. This study aimed to investigate the role of miR-143-5p in the EMT of RPE cells induced by palmitic acid (PA).

METHODS

ARPE-19 cells were treated with PA to induce EMT, followed by E-cadherin and α-smooth muscle actin (α-SMA) expression and the microRNA expression profile analyses. Subsequently, miR-143-5p mimics/inhibitors, and plasmids expressing its predicted target gene c-JUN-dimerization protein 2 (JDP2), were transfected in ARPE-19 cells using lipofectamine 3000, and followed by PA treatment. Their impacts on EMT were explored using wound healing and Western blot assays. Additionally, miR-143-5p mimics and JDP2-expressing plasmid were co-transfected into ARPE-19 cells and treated with PA to explore whether PA induced EMT of ARPE-19 cells via the miR-143-5p/JDP2 axis.

RESULTS

PA decreased E-cadherin expression and increased those of α-SMA and miR-143-5p. Inhibiting miR-143-5p suppressed the migration of ARPE-19 cells and altered the expressions of E-cadherin and α-SMA. However, additional PA treatment attenuated these alterations. JDP2 was a target of miR-143-5p. Overexpression of JDP2 inhibited the EMT of ARPE-19 cells, resulting in α-SMA downregulation and E-cadherin upregulation, which were reversed by additional PA treatment via inhibiting JDP2 expression. Overexpression of miR-143-5p reversed the effect of JDP2 on the EMT of ARPE-19 cells and additional PA treatment markedly enhanced the effect of miR-143-5p mimics.

CONCLUSION

PA promotes EMT of ARPE-19 cells via regulating the miR-143-5p/JDP2 axis, and these findings provide significant insights into the potential targeting of this axis to treat proliferative vitreoretinopathy.

Nanobiotechnological approaches in osteosarcoma therapy: Versatile (nano)platforms for theranostic applications

Constructive achievements in the field of nanobiotechnology and their translation into clinical course have led to increasing attention towards evaluation of their use for treatment of diseases, especially cancer. Osteosarcoma (OS) is one of the primary bone malignancies that affects both males and females in childhood and adolescence. Like other types of cancers, genetic and epigenetic mutations account for OS progression and several conventional therapies including chemotherapy and surgery are employed. However, survival rate of OS patients remains low and new therapies in this field are limited. The purpose of the current review is to provide a summary of nanostructures used in OS treatment. Drug and gene delivery by nanoplatforms have resulted in an accumulation of therapeutic agents for tumor cell suppression. Furthermore, co-delivery of genes and drugs by nanostructures are utilized in OS suppression to boost immunotherapy. Since tumor cells have distinct features such as acidic pH, stimuli-responsive nanoparticles have been developed to appropriately target OS. Besides, nanoplatforms can be used for biosensing and providing phototherapy to suppress OS. Furthermore, surface modification of nanoparticles with ligands can increase their specificity and selectivity towards OS cells. Clinical translation of current findings suggests that nanoplatforms have been effective in retarding tumor growth and improving survival of OS patients.

Mir-34a: a regulatory hub with versatile functions that controls osteosarcoma networks

Osteosarcoma (OS) is one of the most prevalent and highly aggressive bone malignancies. The treatment strategies of OS is under standard regimens, including surgical resection, chemotherapy, and other adjuvant therapy. However, the 5-year survival rate is still unsatisfactory. Previous studies have demonstrated that the expression of miR-34a decreases in osteosarcoma, which is involved in regulating numerous genes directly or indirectly at the post-transcriptional level and other pathways. Thus, miR-34a plays an important role in mediating OS cell proliferation, differentiation, migration, and apoptosis, and might be a pivotal biomarker for OS with diagnostic and therapeutic potentials. In this review, we aim to summarize the relationship between miR-34a and OS, with an emphasis on the specific mechanisms in OS development referring to miR-34a. Moreover, the potential role of miR-34a as a diagnostic, prognostic, and therapeutic candidate for OS would be presented in detail. However, the molecular mechanisms related to miR-34a and OS remain elusive, and more investigations are needed to reach a comprehensive understanding.

KLF9 regulates miR-338-3p/NRCAM axis to block the progression of osteosarcoma cells

Background: MiR-338-3p is revealed to serve as a tumor suppressor in several carcinomas. Whereas, the effect of miR-338-3p in the progression of osteosarcoma has not been explored. The aim of this paper was to analyze the functional influences of miR-338-3p on osteosarcoma progression and the potential mechanism.

Methods: The expression of genes and miRNAs in osteosarcoma cells was assessed via western blotting or quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Osteosarcoma cellular proliferation was explored by MTT and EdU incorporation assay. Osteosarcoma cellular migratory and invasive capacity was explored by wound-healing and transwell assay. Bioinformatics approaches were adopted to predict target genes. The relationships between miR-338-3p and neuron‑glial‑related cell adhesion (NRCAM), between kruppel-like factor 9 (KLF9) and miR-338-3p were verified by dual-luciferase reporter assay.

Results: We found that miR-338-3p was reduced in osteosarcoma and that higher expression of miR-338-3p suppressed proliferative, invasive and migratory ability of osteosarcoma cells. Furthermore, the result showed that overexpression of NRCAM could reduce the anti-tumor role of miR-338-3p in osteosarcoma cells. In addition, we found that overexpression of KLF9 could enhance the expression level of miR-338-3p in osteosarcoma cells.

Conclusion: The KLF9/miR-338-3p/NRCAM axis played a significant role in regulating osteosarcoma progression, which may become a promising therapeutic method for osteosarcoma.

The Biological Function of MicroRNAs in Bone Tumors

Micro ribonucleic acids (miRNAs) are small endogenous noncoding RNAs molecules that regulate gene expression post-transcriptionally. A single miRNA is able to target hundreds of specific messenger RNA (mRNAs) by binding to the 3′-untranslated regions. miRNAs regulate different biological processes such as cell proliferation, differentiation and apoptosis. Altered miRNA expression is certainly related to the development of the most common human diseases, including tumors. Osteosarcoma (OS), Ewing’s Sarcoma (ES), and Chondrosarcoma (CS) are the most common primary bone tumors which affect mainly children and adolescents. A significant dysregulation of miRNA expression, in particular of mir-34, mir-21, mir-106, mir-143, and miR-100, has been revealed in OS, ES and CS. In this context, miRNAs can act as either tumor suppressor genes or oncogenes, contributing to the initiation and progression of bone tumors. The in-depth study of these small molecules can thus help to better understand their biological functions in bone tumors. Therefore, this review aims to examine the potential role of miRNAs in bone tumors, especially OS, ES and CS, and to suggest their possible use as potential therapeutic targets for the treatment of bone tumors and as biomarkers for early diagnosis.

The Emerging Role of MicroRNAs in Bone Diseases and Their Therapeutic Potential

MicroRNAs (miRNAs) are a class of small (20-24 nucleotides), highly conserved, non-coding RNA molecules whose main function is the post-transcriptional regulation of gene expression through sequence-specific manners, such as mRNA degradation or translational repression. Since these key regulatory molecules are implicated in several biological processes, their altered expression affects the preservation of cellular homeostasis and leads to the development of a wide range of pathologies. Over the last few years, relevant investigations have elucidated that miRNAs participate in different stages of bone growth and development. Moreover, the abnormal expression of these RNA molecules in bone cells and tissues has been significantly associated with the progression of numerous bone diseases, including osteoporosis, osteosarcoma, osteonecrosis and bone metastasis, among others. In fact, miRNAs regulate multiple pathological mechanisms, including altering either osteogenic or osteoblast differentiation, metastasis, osteosarcoma cell proliferation, and bone loss. Therefore, in this present review, aiming to impulse the research arena of the biological implications of miRNA transcriptome in bone diseases and to explore their potentiality as a theragnostic target, we summarize the recent findings associated with the clinical significance of miRNAs in these ailments.

Identification of potential core genes in gastric cancer using bioinformatics analysis

Background

Gastric cancer is the third leading cause of cancer-related mortality in China. Most patients with gastric cancer have no obvious early symptoms; thus, many of them are in the middle and late stages of gastric cancer at first diagnosis and miss the best treatment opportunity. Molecular targeted therapy is particularly important in changing this status quo.

Methods

Three microarray datasets (GSE29272, GSE33651, and GSE54129) were selected from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened using GEO2R. The Database for Annotation, Visualization and Integrated Discovery (DAVID) was used to analyze the functional features of these DEGs and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. The protein-protein interaction (PPI) of these DEGs was visualized by Cytoscape software. The expressions of hub genes were evaluated based on Gene Expression Profiling Interactive Analysis (GEPIA). Moreover, we used the online Kaplan-Meier plotter survival analysis tool to evaluate the prognostic values of hub genes. The Target Scan database was used to predict microRNAs that could regulate the target gene, collagen type IV alpha 1 chain (COL4A1). The OncomiR database was used to analyze the expression levels of three microRNAs, as well as the relationships with tumor stage, grade, and prognosis.

Results

We identified 78 DEGs, including 53 upregulated genes and 25 downregulated genes. The DEGs were mainly enriched in extracellular matrix organization, extracellular structure organization, and response to wounding. Moreover, three KEGG pathways were markedly enriched, including focal adhesion, complement and coagulation cascades, and extracellular matrix (ECM)-receptor interaction. Among these 78 genes, we selected 10 hub genes. The overexpression levels of these hub genes were closely related to poor prognosis and the development of gastric cancer (except for COL3A1, LOX, and CXCL8). Moreover, we found that microRNA-29a-3p, miR-29b-3p, and miR-29c-3p were the potential microRNAs that could regulate the target gene, COL4A1.

Conclusions

Our results showed that FN1, COL1A1, TIMP1, COL1A2, SPARC, COL4A1, and SERPINE1 could contribute to the development of novel molecular targets and biomarker-driven treatments for gastric cancer.

miR-877-3p inhibits tumor growth and angiogenesis of osteosarcoma through Fibroblast Growth Factor 2 signaling

Osteosarcoma (OS) is the most common high-grade malignant bone tumor in teenagers. MicroRNAs can function as posttranscriptional regulators of gene expression, playing critical roles in cancer dev-877-3p in OS. Quantitative real-time RT-PCR was carried out for detecting miR-877-3p expression in OS. The effects of miR-877-3p on proliferation was analyzed via MTT, colony formation, and flow cytometry assays. Angiogenesis of endothelial cells were investigated by wound healing and tube formation assay. Gene profiling based on PCR array and luciferase reporter assay were conducted to determine target genes of miR-877-3p. In-vivo study was used to determine the effects of miR-877-3p on the tumor growth. The expression of miR-877-3p was markedly downregulated in OS tissues and cell lines. Low expression of miR-877-3p predicts poor prognosis of OS patients. miR-877-3p overexpression was found to inhibit the proliferation of OS cell lines. The angiogenesis assays showed that miR-877-3p attenuated the angiogenesis. Further mechanism studies showed that miR-877-3p can reduce (Fibroblast Growth Factor 2) FGF2 expression in OS cells by binding to the 3’UTR end of FGF2. Moreover, increased expression of miR-877-3p was responsible for the inhibition of tumor growth and angiogenesis. Taken together, our findings indicated that miR-877-3p might exhibit tumor suppressive role by targeting FGF2 signaling, which may serve as potential target for OS.

DCAF1-targeting microRNA-3175 activates Nrf2 signaling and inhibits dexamethasone-induced oxidative injury in human osteoblasts

Activation of nuclear-factor-E2-related factor 2 (Nrf2) signaling can protect human osteoblasts from dexamethasone-induced oxidative injury. DDB1 and CUL4 associated factor 1 (DCAF1) is a novel ubiquitin E3 ligase for Nrf2 protein degradation. We identified a novel DCAF1-targeting miRNA, miR-3175. RNA pull-down, Argonaute 2 RNA-immunoprecipitation, and RNA fluorescent in situ hybridization results confirmed a direct binding between miR-3175 and DCAF1 mRNA in primary human osteoblasts. DCAF1 3′-untranslated region luciferase activity and its expression were significantly decreased after miR-3175 overexpression but were augmented with miR-3175 inhibition in human osteoblasts and hFOB1.19 osteoblastic cells. miR-3175 overexpression activated Nrf2 signaling, causing Nrf2 protein stabilization, antioxidant response (ARE) activity increase, and transcription activation of Nrf2-dependent genes in human osteoblasts and hFOB1.19 cells. Furthermore, dexamethasone-induced oxidative injury and apoptosis were largely attenuated by miR-3175 overexpression in human osteoblasts and hFOB1.19 cells. Importantly, shRNA-induced silencing or CRISPR/Cas9-mediated Nrf2 knockout abolished miR-3175 overexpression-induced osteoblast cytoprotection against dexamethasone. Conversely, DFAC1 knockout, by the CRISPR/Cas9 method, activated the Nrf2 cascade and inhibited dexamethasone-induced cytotoxicity in hFOB1.19 cells. Importantly, miR-3175 expression was decreased in necrotic femoral head tissues of dexamethasone-taking patients, where DCAF1 mRNA was upregulated. Together, silencing DCAF1 by miR-3175 activated Nrf2 signaling to inhibit dexamethasone-induced oxidative injury and apoptosis in human osteoblasts.

Effect of tumor-associated macrophages on lncRNA PURPL/miR-363/PDZD2 axis in osteosarcoma cells

Tumor-associated macrophages (TAMs) are known to participate in osteosarcoma (OS) progression. As demonstrated in our previous research, miR-363 played a tumor inhibitory effect in OS cells via lowering the PDZ domain containing 2 (PDZD2) expression. The regulatory roles of TAMs on miR-363/PDZD2 and the internal mechanism relating to long noncoding RNA p53 upregulated regulator of P53 levels (lncRNA PURPL) are examined in this study. TAM-like macrophages were formed by inducing CD14⁺ peripheral blood mononuclear cells (PBMCs). The TAMs migration was detected after MG-63 cells transfected with miR-363 mimics or inhibitors. We then analyzed the regulatory activity of PURPL on miR-363 expression. We also tested the influences of PURPL overexpression/knockdown on MG-63 cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT), as well as TAMs migration. Silence in PDZD2 expression was used to confirm the effects of PURPL on MG-63 cells. We successfully induced TAM-like macrophages. MG-63 cells transfecting miR-363 mimics suppressed TAMs migration while transfecting a converse effect was seen in miR-363 inhibitor. TAMs raised PURPL expression in MG-63 cells, which was an upstream regulator of miR-363. Along with TAMs migration, PURPL overexpression promoted MG-63 cell proliferation, migration, invasion, and EMT. An opposite influence was seen due to the PURPL knockdown. The silence of PDZD2 weakened the influences of PURPL overexpression on MG-63 cells and TAMs migration. On modulating the PURPL/miR-363/PDZD2 axis, TAMs-promoted OS development might be achieved.

MicroRNA-382-5p inhibits osteosarcoma development and progression by negatively regulating VEZF1 expression

Human osteosarcoma is the most frequent malignant primary bone tumor that mainly occurs in young adults and children. MicroRNAs (miRNAs/miRs) are abnormally expressed in human osteosarcoma and contribute to osteosarcoma initiation and development. The present study aimed to investigate the role of miR-382-5p in the nosogenesis of osteosarcoma and to identify a novel target for osteosarcoma treatment. miR-382-5p expression was detected in human osteosarcoma clinical tissues and cell lines, including 143B, U2OS and MG63, via reverse transcription-quantitative PCR analysis. Multiple bioinformatic prediction toowe used to identify the potential target genes of miR-382-5p and vascular endothelial zinc finger 1 (VEZF1), which were validated via the dual-luciferase reporter assay. MG63 and U2OS cells were transfected with miR-382-5p mimics. The Cell Counting Kit-8 assay was performed to assess cell proliferation, while the Transwell assay was performed to assess migration and invasion. Cell colony formation was measured via crystal violet staining, and apoptosis was assessed via Annexin V/propidium iodide staining. The wound healing assay was performed to assess the migratory ability of U2OS and MG63 cells. Antitumor effects of miR-382-5p were evaluated in nude mice xenografts using U2OS cells. The results demonstrated that miR-382-5p expression was markedly downregulated in human osteosarcoma tissues and cell lines compared with adjacent normal tissues. Transfection of miR-382-5p mimics into MG63 and U2OS cells significantly inhibited the malignant behaviors of cells, including decreased proliferation, migration, diminished colony formation and invasion, and promoted osteosarcoma cell apoptosis. Bioinformatics prediction indicated that VEZF1 is a direct target gene of miR-382-5p. Overexpression of VEZF1 restored osteosarcoma tumor development inhibited by miR-382-5p in vivo. In addition, overexpression of miR-382-5p restrained the growth of xenograft osteosarcoma in nude mice following co-transfection, and overexpression of VEZF1 attenuated the inhibitory effect of miR-382-5p in nude mice. miR-382-5p acted as a tumor suppressor gene and inhibited the malignant biological behaviors of human osteosarcoma cells and functions associated with directly targeting VEZF1. Taken together, these results suggest that the miR-382-5p/VEZF1 interaction has an important role in osteosarcoma development and progression, and thus may be used as a diagnostic and therapeutic target for osteosarcoma.

MicroRNA-545-5p regulates apoptosis, migration and invasion of osteosarcoma by targeting dimethyladenosine transferase 1

The metastasis of osteosarcoma is a major threat to both adolescents and young adults. Identifying novel targets that may prevent osteosarcoma metastasis is critical in developing advanced clinical therapies for treating this cancer. The present study aimed to explore the mechanism of microRNA (miR)-545-5p in the metastasis of osteosarcoma. The present study identified miR-545-5p as a potential target that was downregulated in both osteosarcoma clinical samples and cell lines, and in the latter, ectopically expressed miR-545-5p caused apoptosis. In addition, miR-545-5p exerted inhibitory effects in osteosarcoma migration and invasion. Overexpression of miR-545-5p induced xenograft growth inhibition in vivo. In addition, miR-545-5p targeted dimethyladenosine transferase 1 (DIMT1), an oncogenic protein that facilitates osteosarcoma proliferation, migration and invasion. Taken together, the results of the present study suggest that miR-545-5p functions as a tumor suppressor in osteosarcoma that promotes apoptosis, while inhibiting migration and invasion by targeting DIMT1. Taken together, the results of the present study suggest two potential novel targets for osteosarcoma treatment and metastasis prevention.

MicroRNA-1226-3p has a tumor-promoting role in osteosarcoma

Osteosarcoma is a malignant bone tumor that commonly occurs in young individuals. It accounts for 10% of solid tumors in those who are 15–19 years old. MicroRNA (miRNA/miR) dysregulation serves a crucial role in the molecular mechanism of osteosarcoma. The present study reported a novel miRNA (miR-1226-3p) and investigated its function in osteosarcoma. miR-1226-3p mimics and miR-1226-3p antisense oligonucleotides were transfected into human osteosarcoma SaOS-2 cells to alter miR-1226-3 expression, while the hFOB 1.19 cell line was used as the control. The apoptosis rate was analyzed using a dead cell apoptosis kit. TNF receptor-associated factor 3 (TRAF3) protein expression was assayed by western blotting. The results of bioinformatics and clinical specimen analyses revealed that higher expression levels of miR-1226-3p were associated with lower survival rates. Additionally, the results of experiments on cultured cells revealed that miR-1226-3p promoted the proliferation of SaOS-2 cells, while miR-1226-3p inhibition decreased cell proliferation and increased apoptosis. Furthermore, it was revealed that miR-1226-3p targeted TRAF3 in SaOS-2 cells. In conclusion, the present study suggested that miR-1226-3p promoted the proliferation of osteosarcoma cells.

Evaluation of cytotoxic activity and anticancer potential of indigenous Rosemary (Rosmarinus officinalis L.) and Oregano (Origanum vulgare L.) dry extracts on MG-63 bone osteosarcoma human cell line

We aimed to investigate the cytotoxic activity of indigenous Rosemary and Oregano freeze-dried extracts upon MG-63 osteosarcoma human cell line. We have determined the influence of analyzed dry extracts on cell morphology, cell survival and cell proliferation. The evaluation of dry extracts effect upon cell proliferation and viability was assessed by means of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) method. For cytotoxicity evaluation, Live & Dead and lactate dehydrogenase assays have been used. To further investigate the potential anticancer effect, we have studied the influence of dry extracts upon cells, by means of caspase-3/7 assay and proliferation cell nuclear antigen (PCNA) expression. Cells were incubated with extracts in the following concentration range (100–700 μg/mL) for 24 hours. According to our results, both dry extracts have shown cytotoxic effects by means of all used methods. Bone osteosarcoma cells viability significantly decreased with increasing concentration of analyzed extracts (beyond 300 μg/mL for Rosemary dry extract and only at 700 μg/mL for Oregano dry extract). According to our results, apoptosis is one of the main mechanisms involved in the cytotoxic properties of analyzed extracts. Moreover, Rosemary extract has also shown decreased expression of PCNA, when compared to control (untreated cells). Both extracts were standardized in phenolic compounds (being a rich source of flavones and phenolcarboxylic acids), so we assume that these are the main constituents involved in the cytotoxic effect. Still, further preclinical studies are needed to confirm the antitumor properties and to go deeply in the molecular mechanisms involved.

miR-26a Reverses Multidrug Resistance in Osteosarcoma by Targeting MCL1

The multidrug resistance (MDR) acquired in human osteosarcoma is a huge obstacle for effective chemotherapy. Recently, microRNA-26a (miR-26a) has been associated with the pathogenesis and progression of osteosarcoma. However, whether it regulates MDR in osteosarcoma is unknown. We show here that miR-26a expression declines in chemoresistant osteosarcoma after neoadjuvant chemotherapy, and its expression correlates with clinical outcome. In addition, compared with sensitive parental cells, miR-26a expression also declines in osteosarcoma MDR cells, together suggesting a negative correlation between miR-26a expression and MDR development in osteosarcoma. We also show that the enforced expression of miR-26a reverses MDR in osteosarcoma cells, and conversely, miR-26a knockdown confers MDR in chemosensitive osteosarcoma cells treated with doxorubicin, methotrexate, or cisplatin. Mechanistically, miR-26a directly targets the pro-survival protein myeloid cell leukemia 1 (MCL1), and in turn, the enforced expression of MCL1 markedly antagonizes miR-26a-decreased MDR in osteosarcoma MDR cells, therefore demonstrating that miR-26a reverses MDR in osteosarcoma by targeting MCL1. Lastly, miR-26a reverses resistance to doxorubicin in osteosarcoma MDR cells xenografted in nude mice. Collectively, these results reveal a negative role and the underlying mechanism of miR-26a in the regulation of MDR in human osteosarcoma, implying a potential tactic of manipulating miR-26a for overcoming MDR in osteosarcoma chemotherapy.

Exosomes in osteosarcoma research and preclinical practice

Osteosarcoma (OS) is a rare soft-tissue malignant tumor with high lung metastasis and mortality rates. Preoperative chemotherapy, surgical resection of the lesion and postoperative chemotherapy are still the main treatments for osteosarcoma. The prognosis, however, is poor for patients with nonresectable, primary metastatic or relapsed disease. Recent studies have shown that targeted therapy for OS based on the characteristics of exosomes is very attractive. Exosomes are nanosized extracellular vesicles (EVs) that participate in cell-to-cell communication by transporting biologically active cargo molecules, causing changes in OS cell function and playing important roles in OS disease progression. With the characteristics of secretory cells, exosomes transport cargo (e.g., microRNAs) that can be used to detect the progress of a disease and can serve as markers and/or therapeutic targets for clinical diagnosis of OS. In this review, the roles of exosomes in OS pathogenesis, invasion, metastasis, drug resistance, diagnosis and treatment are summarized. In addition, this article elaborates a series of challenges to overcome before exosomes are applied in clinical practice and provides suggestions based on current evidence for the direction of future research.

MAFG-driven osteosarcoma cell progression is inhibited by a novel miRNA miR-4660

Osteosarcoma (OS) is the most common primary bone malignancy in the adolescent population. MAFG (v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog G) forms a heterodimer with Nrf2 (NF-E2-related factor 2), binding to antioxidant response element (ARE), which is required for Nrf2 signaling activation. We found that MAFG mRNA and protein expression is significantly elevated in human OS tissues as well as in established and primary human OS cells. In human OS cells, MAGF silencing or knockout (KO) largely inhibited OS cell growth, proliferation, and migration, simultaneously inducing oxidative injury and apoptosis activation. Conversely, ectopic overexpression of MAFG augmented OS cell progression in vitro. MicroRNA-4660 (miR-4660) directly binds the 3′ untranslated region (UTR) of MAFG mRNA in the cytoplasm of OS cells. MAFG 3′ UTR luciferase activity and expression as well as OS cell growth were largely inhibited with forced miR-4660 overexpression but augmented with miR-4660 inhibition. In vivo, MAGF short hairpin RNA (shRNA) or forced overexpression of miR-4660 inhibited subcutaneous OS xenograft growth in severe combined immunodeficient mice. Furthermore, MAFG silencing or miR-4660 overexpression inhibited OS xenograft in situ growth in proximal tibia of the nude mice. In summary, MAFG overexpression-driven OS cell progression is inhibited by miR-4660. The miR-4660-MAFG axis could be novel therapeutic target for human OS.

Overexpression of miR-329-3p sensitizes osteosarcoma cells to cisplatin through suppression of glucose metabolism by targeting LDHA

Osteosarcoma (OS) is one of the most frequent malignant bone tumor types. Traditional treatments of OS involve standard chemotherapy or combination with radiation before and after surgery. Cisplatin is one of the most effective chemotherapeutic drugs used for treating osteosarcoma. However, patients with advanced tumor stages develop cisplatin resistance, leading to a major clinical challenge. In this study, we investigated the roles of miR-329-3p in cisplatin sensitivity of osteosarcoma cells. We found miR-329-3p was significantly downregulated in osteosarcoma tissues compared with normal bone tissues. Overexpression of miR-329-3p suppressed osteosarcoma cell proliferation. Moreover, we observed low-toxic cisplatin treatments suppressed miR-329-3p but higher concentrations of cisplatin-induced miR-329-3p expression. In addition, miR-329-3p was significantly downregulated in cisplatin-resistant Saos-2 cells which displayed elevated glucose metabolism. Overexpression of miR-329-3p significantly impaired glucose metabolism of Saos-2 cells. Bioinformatics analysis and luciferase assay consistently demonstrated the glycolysis enzyme, lactate dehydrogenase-A (LDHA) was a direct target of miR-329-3p in osteosarcoma cells. Rescue experiments revealed restoration of LDHA in miR-329-3p-overexpressed cisplatin-resistant cells effectively recovered glucose metabolism, resulting in increased cisplatin resistance. This study demonstrates a miR-329-3p-LDHA-glucose metabolism-cisplatin resistance axis in osteosarcoma cells, providing a miRNA-based therapeutic strategy against chemoresistant osteosarcoma.

Comprehensive Analysis of Aerobic Exercise-Related Genes Identifies CDCA4 That Promotes the Progression of Osteosarcoma

Background

Exercise has a positive impact on patients with osteosarcoma, improving function, reducing disability, maintaining independence and quality of life. Exercise may also directly affect the effectiveness of cancer treatment. Cell division cycle-associated protein 4 (CDCA4) is reported to function importantly during numerous human cancers development. Nevertheless, the details toward CDCA4 function are still to be investigated.

Methods

This study comprehensively analyzed the GSE74194 database and obtained aerobic exercise-related genes. Protein-protein interaction network (PPI) and Gene Ontology (GO) analysis were performed on the differentially expressed genes (DEGs). Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and tumor genome atlas (TCGA) data mining were applied to measure aerobic exercise-related gene CDCA4 level in osteosarcoma tissue. We conducted lots of functional experiments to uncover CDCA4 function and its corresponding mechanism in osteosarcoma.

Results

We screened a total of 547 DEGs related to aerobic exercise, of which 373 were up-regulated and 174 were down-regulated. PPI analysis revealed 90 genes that might play key roles. GO analysis showed that aerobic exercise-related DEGs were significantly enriched during the mitotic cell cycle, cell division, mitotic nuclear division and sister chromatid segregation, nuclear division, microtubule cytoskeleton organization involved protein, microtubule-based process, spindle organization, G2/M transition of mitotic cell cycle. Our results indicated that CDCA4 was increased in osteosarcoma tissues and cell lines, and its level had association with high mortality of osteosarcoma patients. Further studies revealed that absence of CDCA4 largely hindered osteosarcoma cancer cell proliferation, invasion, and migration.

Conclusion

Comprehensive bioinformatics analysis improves our understanding of the underlying molecular mechanisms of aerobic exercise on osteosarcoma. This provides evidence for the effect of aerobic exercise on CDCA4 expression. Our data suggested that CDCA4 could facilitate osteosarcoma development, and gave a hint that CDCA4 was a candidate target in the treatment of osteosarcoma, aerobic exercise might help the treatment and prognosis of patients with osteosarcoma.

Schisandrin B Inhibits Cell Viability and Migration, and Induces Cell Apoptosis by circ_0009112/miR-708-5p Axis Through PI3K/AKT Pathway in Osteosarcoma

Osteosarcoma is a primary tumor of bone and its incidence is increasing. Schisandrin B (Sch B), a generally used lignan in Chinese medicine, has been found to repress cancer progression. This study aims to reveal the effects and regulatory mechanism of Sch B in the viability, apoptosis and migration of osteosarcoma cells. In this study, we found circ_0009112 expression was higher and miR-708-5p expression was lower in SaOS2 and U2OS cells than in hFOB1.19 cells. Circ_0009112 expression was downregulated, but miR-708-5p was upregulated by Sch B treatment in a dose-dependent manner in SaOS2 and U2OS cells. Sch B exposure inhibited osteosarcoma development in vitro and in vivo; however, these effects were restored by circ_0009112. Furthermore, circ_0009112 acted as a sponge of miR-708-5p. Circ_0009112 regulated PI3K/AKT pathway after Sch B treatment by associating with miR-708-5p. Sch B exposure inhibited cell viability and migration, whereas promoted cell apoptosis by regulating circ_0009112/miR-708-5p axis through PI3K/AKT pathway in osteosarcoma cells. This study provided a theoretical basis for further studying osteosarcoma therapy with Sch B.

miR-4295 promotes cell proliferation, migration and invasion of osteosarcoma through targeting interferon regulatory factor 1

Osteosarcoma (OS) is the most common form of primary malignant bone tumor. Despite encouraging progress in the treatment of OS, the survival rate for patients with OS has remained unchanged over the past 40 years. It has been established that miRNA plays a crucial regulatory role in the progression and development of OS. To explore the potential association of miRNAs with OS, bioinformatics techniques were used to screen for differentially expressed miRNA genes in OS in the Gene Expression Omnibus database. In the GSE70367 database, it was revealed that miR-4295 expression was abnormally elevated in the expression of OS cells. To characterize the potential function of miR-4295 in OS, the expression levels of miR-4295 in 30 samples of OS and adjacent normal tissues was examined. The results revealed that the expression of miR-4295 was significantly increased in OS tissues compared with the paired normal tissues. Moreover, the expression levels of miR-4295 in OS cell lines (MG-63 and Saos-2) were significantly higher compared with those in the normal human mesenchymal stem cells. In addition, miR-4295 was associated with OS cell proliferation, migration and invasion. Furthermore, it was demonstrated that the expression of interferon regulatory factor (IRF)1, a tumor suppressor, was regulated by miR-4295 directly in OS cells. Taken together, the present results revealed that miR-4295 may act as a tumor activator by targeting IRF1 during the progression of OS. Investigating miR-4295 may provide novel insight into the mechanisms of OS metastasis, and inhibition and targeting miR-4295 may be a novel therapeutic strategy for the treatment of OS.

Upregulated miRNA-543 promotes the proliferation and migration of gastric carcinoma by downregulating KLF6

This study aims to uncover the potential function of MicroRNA-543 (miRNA-543) in the pathogenesis of gastric carcinoma and the possible mechanism. MiRNA-543 levels in gastric carcinoma tissues and cell lines were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Regulatory effects of miRNA-543 on proliferative and migratory abilities of AGS and MKN45 cells were assessed. The downstream target of miRNA-543 was predicted by online bioinformatics and verified by dual-luciferase reporter gene assay. At last, rescue experiments were carried out to uncover the interaction between miRNA-543 and Krüppel-like factor 6 (KLF6) in the progression of gastric carcinoma. MiRNA-543 was upregulated in gastric carcinoma tissues and cell lines. Particularly, gastric carcinoma patients with advanced stage or positive metastasis expressed higher abundance of miRNA-543. Overexpression of miRNA-543 promoted proliferative ability in gastric carcinoma, manifesting as increased viability, EdU-positive ratio and migratory cell number in AGS and MKN45 cells. KLF6 was proved to be the downstream target of miRNA-543. Both mRNA and protein levels of KLF6 were negatively regulated by miRNA-543 in gastric carcinoma cells. Silence of KLF6 was able to reverse the regulatory effects of miRNA-543 inhibitor on proliferative and migratory abilities in gastric carcinoma. MiRNA-543 is highly expressed in gastric carcinoma. It accelerates gastric carcinoma cells to proliferate and migrate by negatively regulating KLF6 level.

The role of extracelluar matrix in osteosarcoma progression and metastasis

Osteosarcoma (OS) is the most common primary bone malignancy and responsible for considerable morbidity and mortality due to its high rates of pulmonary metastasis. Although neoadjuvant chemotherapy has improved 5-year survival rates for patients with localized OS from 20% to over 65%, outcomes for those with metastasis remain dismal. In addition, therapeutic regimens have not significantly improved patient outcomes over the past four decades, and metastases remains a primary cause of death and obstacle in curative therapy. These limitations in care have given rise to numerous works focused on mechanisms and novel targets of OS pathogenesis, including tumor niche factors. OS is notable for its hallmark production of rich extracellular matrix (ECM) of osteoid that goes beyond simple physiological growth support. The aberrant signaling and structural components of the ECM are rich promoters of OS development, and very recent works have shown the specific pathogenic phenotypes induced by these macromolecules. Here we summarize the current developments outlining how the ECM contributes to OS progression and metastasis with supporting mechanisms. We also illustrate the potential of tumorigenic ECM elements as prognostic biomarkers and therapeutic targets in the evolving clinical management of OS.

MicroRNA-652 promotes cell proliferation and osteosarcoma invasion by directly targeting KLF9

Previous studies have demonstrated that various microRNAs (miRNAs or miRs) are abnormally expressed in osteosarcoma (OS) and serve roles in its malignant development. An in-depth understanding of the specific roles of dysregulated miRNAs in OS may be important for cancer research and the identification of novel therapeutic targets. In the current study, reverse transcription-quantitative PCR was performed to determine miR-652 expression in OS tissues and cell lines. Cell Counting Kit-8 and Transwell invasion assays were used for assessing the effect of miR-652 on the proliferation and invasion of OS cells. Herein, miR-652 expression was assessed in OS and the effects and molecular mechanisms of miR-652 in OS cells were examined. The results revealed that miR-652 expression was significantly upregulated in OS tissues and cell lines compared with adjacent normal tissues and a normal human osteoblast cell line. Furthermore, miR-652 downregulation inhibited the proliferation and invasion of OS cells. miR-652 was also demonstrated to directly interact with the 3'-untranslated region of kruppel-like factor 9 (KLF9) and miR-652 negatively regulated KLF9 expression in OS cells. miR-652 and KLF9 mRNA levels were also revealed to be inversely correlated in OS tissues. Treatment with KLF9 small interfering RNA abolished the suppression of OS proliferation and invasion induced by miR-652 downregulation. miR-652 may serve an oncogenic role in OS cells by targeting KLF9 directly. The results also indicated that miR-652 may be an effective novel therapeutic target for the treatment of patients with OS.

Analysis of changes in the expression of Notch1 and HES1 and the prognosis of osteosarcoma patients following surgery

The present study aimed to analyze the changes in the expression of Notch1 and hairy and enhancer of split-1 (HES1) and the prognosis of patients with osteosarcoma following surgery. Samples from 62 patients with osteosarcoma treated at Shandong Cancer hospital from April, 2011 to June, 2013 were collected as the research group, and those from 52 healthy individuals undergoing physical examination were collected as the control group. The expression levels of Notch1 and HES1 in the serum of patients with osteosarcoma were measured by ELISA before and after surgery. Pearson's correlation analysis was used to analyze the correlation between Notch1 expression and HES1 expression in the osteosarcoma patients. According to the expression levels of Notch1 and HES1, the patients were divided into the high expression group and the low expression group, and the 5-year survival rate of the patients was observed. The expression levels of Notch1 and HES1 in the osteosarcoma patients before surgery were higher than those after surgery (P<0.05). The sensitivity, specificity and AUC of Notch1 for osteosarcoma were 93.55%, 58.06% and 0.732 respectively, and those of HES1 were 82.26%, 61.29% and 0.766, respectively. The expression level of Notch1 positively correlated with the expression level of HES1 in the osteosarcoma patients (r=0.795, P<0.001). According to the expression levels of Notch1 and HES1, the patients were divided into the high and low expression groups. The survival rate of the low expression group was significantly higher than that of the high expression groups (P=0.045). Finally, multiple factors were analyzed by logistic regression, and it was found that tumor location, chemotherapy response, tumor size, Notch1 and HES1 were independent risk factors for prognosis. Notch1 and HES1 exhibited a low expression in patients following surgery. ROC curve analysis revealed that the two indicators had good diagnostic efficacy and were expected to become markers for diagnosis and prognosis of osteosarcoma.

MiR-135b Induces Osteosarcoma Invasion by the Modulation of FOXO-1 and c-Myc

Background: Osteosarcoma (OS) is the most common type of bone malignancy. Many studies have attempted to find the association between microRNAs and cancer-associated processes. Alterations in miRNA expression through genetic or epigenetic changes, impairment of transcription factors, and ectopic expression of miRNAs induce the development and progression of cancer. Although miR-135b has been thoroughly documented as an oncogene in the majority of studies, some controversies remain about the conflicting role of miR-135b as a tumor-suppressor. Objectives: The present study aimed at investigating the oncogenic and/or tumor-suppressing role of miR-135b in human OS. Methods: In this study, 21 OS tissue samples, along with 21 adjacent bone tissues (normal) as control specimens were collected to analyze the expression of miR-135b. The Saos2 cell-line was transiently transfected with the miR-135b mimic and inhibitor to assess its effect on two critical transcription factors, namely FOXO-1 and c-Myc. qRT-PCR was performed to quantify the expression of miR-135b in both OS tissues and the Saos2 cell-line. The MTT, cell migration, and cell invasion assays were used to characterize the miR-135b function. The western blot analysis was carried out to monitor the targets of miR-135b. Finally, the changes in cellular functions such as migration and invasion, following the transfection of miR-135b mimic and inhibitor, were verified. Results: The results showed that in comparison with the adjacent normal bone tissues, the expression of miR-135b was higher in OS tissue samples, which inversely correlated with the expression rate of FOXO-1, whereas the expression of c-Myc had a direct relationship to miR-135b expression. Functionally, the miR-135b mimic led to an increase in cell proliferation, invasion, and migration of OS cancer cells. Conclusions: MiR-135b induces the proliferation and invasion of OS cells by the degradation of FOXO-1 and upregulation of c-Myc.

Wireless Electrochemotherapy by Selenium-Doped Piezoelectric Biomaterials to Enhance Cancer Cell Apoptosis

Cancer residues around the surgical site remain a significant cause of treatment failure with cancer recurrence. To prevent cancer recurrence and simultaneously repair surgery-caused defects, it is urgent to develop implantable biomaterials with anticancer ability and good biological activity. In this work, a functionalized implant is successfully fabricated by doping the effective anticancer element selenium (Se) into the potassium-sodium niobate piezoceramic, which realizes the wireless combination of electrotherapy and chemotherapy. Herein, we demonstrate that the Se-doped piezoelectric implant can cause mitochondrial damage by increasing intracellular reactive oxygen species levels and then trigger the caspase-3 pathway to significantly promote apoptosis of osteosarcoma cells in vitro. Meanwhile, its good biocompatibility has been verified. These results are of great importance for future deployment of wireless electro- and chemostimulation to modulate biological process around the defective tissue.

MicroRNAs signatures, bioinformatics analysis of miRNAs, miRNA mimics and antagonists, and miRNA therapeutics in osteosarcoma

MicroRNAs (miRNAs) involved in key signaling pathways and aggressive phenotypes of osteosarcoma (OS) was discussed, including PI3K/AKT/MTOR, MTOR AND RAF-1 signaling, tumor suppressor P53- linked miRNAs, NOTCH- related miRNAs, miRNA -15/16 cluster, apoptosis related miRNAs, invasion-metastasis-related miRNAs, and 14Q32-associated miRNAs cluster. Herrin, we discussed insights into the targeted therapies including miRNAs (i.e., tumor-suppressive miRNAs and oncomiRNAs). Using bioinformatics tools, the interaction network of all OS-associated miRNAs and their targets was also depicted.

miR-107 inhibition upregulates CAB39 and activates AMPK-Nrf2 signaling to protect osteoblasts from dexamethasone-induced oxidative injury and cytotoxicity

To human osteoblasts dexamethasone (DEX) treatment induces significant oxidative injury and cytotoxicity. Inhibition of CAB39 (calcium binding protein 39)-targeting microRNA can induce CAB39 upregulation, activating AMP-activated protein kinase (AMPK) signaling and offering osteoblast cytoprotection. Here we identified a novel CAB39-targeting miRNA: the microRNA-107 (miR-107). RNA-Pull down assay results demonstrated that the biotinylated-miR-107 directly binds to CAB39 mRNA in OB-6 human osteoblastic cells. Forced overexpression of miR-107, by infection of pre-miR-107 lentivirus or transfection of wild-type miR-107 mimic, largely inhibited CAB39 expression in OB-6 cells and primary human osteoblasts. Contrarily, miR-107 inhibition, by antagomiR-107, increased its expression, resulting in AMPK cascade activation. AntagomiR-107 largely attenuated DEX-induced cell death and apoptosis in OB-6 cells and human osteoblasts. Importantly, osteoblast cytoprotection by antagomiR-107 was abolished with AMPK in-activation by AMPKα1 dominant negative mutation, silencing or knockout. Further studies demonstrated that antagomiR-107 activated AMPK downstream Nrf2 cascade to inhibit DEX-induced oxidative injury. Conversely, Nrf2 knockout almost abolished antagomiR-107-induced osteoblast cytoprotection against DEX. Collectively, miR-107 inhibition induced CAB39 upregulation and activated AMPK-Nrf2 signaling to protect osteoblasts from DEX-induced oxidative injury and cytotoxicity.

Inhibition of miR-9 decreases osteosarcoma cell proliferation

Osteosarcoma (OS) is the most common primary bone tumor that affects adolescents and young adults. Disruption of microRNA (miRNA) regulation is well established in the pathophysiology of different cancers, including OS. Increased expression of miR-9 in OS positively correlates with the tumor size, clinical stage, and distant metastasis. In the present study, we used two different OS cell lines, MG-63 and Saos-2, as in vitro models. miR-9 inhibitor and miR-9 mimics were used to study the function of miR-9 in these two cell lines. We determined the effect of miR-9 inhibition on cell proliferation, cell cycle, apoptosis, and the protein expression of different genes. Our results demonstrated that miR-9 inhibition in the human OS cell lines suppresses their metastatic potential, as determined by decreased cell proliferation and cell cycle arrest, decreased invasion, and increased apoptosis. The Western blot analysis showed that E-cadherin, matrix metalloproteinase 13, forkhead box O3, Bcl-2-like protein 11, and β-catenin are involved in miR-9 signaling. Moreover, miR-9 mimics rescued the effects caused by the inhibition of miR-9 in the OS cell lines. Our findings suggest that miR-9 is important for mediating OS cell migration, invasion, metastasis, and apoptosis. Inhibition of miR-9 could be further explored as a therapeutic target to treat OS.

LncRNA LINC00313 Knockdown Inhibits Tumorigenesis and Metastasis in Human Osteosarcoma by Upregulating FOSL2 through Sponging miR-342-3p

PURPOSE

Osteosarcoma (OS) is the most common primary bone tumor, with high morbidity in infants and adolescents. Long noncoding RNA LINC00313 has been found to modulate papillary thyroid cancer tumorigenesis and to be dysregulate in lung cancer. However, the role of LINC00313 in OS has not yet been addressed.

MATERIALS AND METHODS

We evaluated mRNA and protein expression using real-time quantitative PCR and Western blotting. Cell proliferation was evaluated using MTT; apoptosis and autophagy were assessed with flow cytometry, Western blotting, and/or GFP-LC3 assay. Transwell assay was conducted to measure cell migration and invasion. Potential target sites for LINC00313 and miR-342-3p were predicted with starBase v.2.0 and TargetScan Human, and verified using luciferase reporter assay, RNA immunoprecipitation, and RNA pull-down assay. In vivo, xenogeneic tumors were induced with U2OS and MG-63 cells, separately.

RESULTS

LINC00313 was upregulated and miR-342-3p was downregulated in OS tissues and cells. High expression of LINC00313 was associated with shorter overall survival. FOSL2 downregulation and miR-342-3p overexpression suppressed cell proliferation and migratory and invasive abilities while promoting apoptosis and autophagy, all of which were consistent with the effects of LINC00313 knockdown. miR-342-3p, sponged by LINC00313, inversely modulated FOSL2 by targeting MG-63 cells, and FOSL2 expression was positively controlled by LINC00313. LINC00313 knockdown suppressed tumor growth in vivo.

CONCLUSION

LINC00313 is upregulated in OS, and LINC00313 knockdown plays a vital anti-tumor role in OS cell progression through a miR-342-3p/FOSL2 axis. Our study suggests that LINC00313 may be a novel, promising biomarker for diagnosis and prognosis of OS.

miR‑193b exhibits mutual interaction with MYC, and suppresses growth and metastasis of osteosarcoma

Emerging evidence has indicated that microRNAs (miRs) are involved in the malignant behavior of cancer. The present study explored the role of miR‑193b in the development and metastasis of osteosarcoma. Compared with F4 osteosarcoma cells, which have a relatively low metastatic potential, highly metastatic F5M2 cells exhibited a lower expression of miR‑193b. Furthermore, miR‑193b exerted negative effects on cell proliferation, colony formation, cell cycle progression, migration and invasion, and induced apoptosis. In vivo studies revealed negative influences of miR‑193b on tumorigenesis and metastasis. The tumor‑suppressive role of miR‑193b was achieved by targeting KRAS and stathmin 1 (STMN1). Notably, overexpression of KRAS and STMN1 attenuated the miR‑193b‑induced inhibition of malignant behaviors. There was a double‑negative regulatory loop between MYC and miR‑193b, with MYC inhibiting miR‑193b expression by directly binding to its promoter region and miR‑193b negatively influencing MYC expression indirectly through some unknown mechanism. Collectively, these findings indicated that miR‑193b may serve a tumor suppressive role in osteosarcoma by targeting KRAS and STMN1. The double‑negative regulatory loop between MYC and miR‑193b may contribute to the sustained upregulation of MYC, the downregulation of miR‑193b, and to the subsequently enhanced expression of KRAS and STMN1, which may eventually lead to the development and metastasis of osteosarcoma.

LncRNA OR3A4 Regulated the Growth of Osteosarcoma Cells by Modulating the miR-1207-5p/G6PD Signaling

Background

Increasing evidence has demonstrated the importance of non-coding RNAs including long non-coding RNA (lncRNA) and microRNAs (miRNAs) in the tumorigenesis of osteosarcoma (OS). Abnormal expression of lncRNA olfactory receptor family 3 subfamily A member 4 (OR3A4) was found in multiple human cancers; however, the function of OR3A4 in OS remains largely unknown.

Materials and Methods

The expression level of OR3A4 in OS tissues and cell lines was detected by RT-qPCR. Cell counting kit-8 assay, colony formation and flow cytometry analysis were performed to determine the growth of OS cells. The targets of OR3A4 were predicted using the miRDB database. The binding between OR3A4 and miRNAs was confirmed by dual-luciferase reporter assay.

Results

OR3A4 was overexpressed in OS tissues and correlated with the advanced progression of OS patients. Down-regulation of OR3A4 significantly inhibited the proliferation and colony formation of OS cells. Mechanistically, OR3A4 acted as a sponge of miR-1207-5p. Glucose-6-phosphate dehydrogenase (G6PD) was identified as a target of miR-1207-5p. Knockdown of OR3A4 increased the expression of miR-1207-5p and consequently, suppressed the level of G6PD in OS cells. Due to the essential role of G6PD in the pentose phosphate pathway (PPP), depletion of OR3A4 inhibited NADPH production, glucose consumption and lactate generation. Decreased level of NADPH by depletion of OR3A4 up-regulated the redox state (ROS) content and resulted in endoplasmic reticulum (ER) stress in OS cells. Restoration of G6PD significantly attenuated the cell growth inhibition induced by OR3A4 knockdown.

Conclusion

Our finding suggested the critical role of OR3A4 in the proliferation of OS cells via targeting the miR-1207-5p/G6PD axis.

The potential of micelleplexes as a therapeutic strategy for osteosarcoma disease

Osteosarcoma (OS) is a rare aggressive bone, presenting low patient survival rate, high metastasis and relapse occurrence, mostly due to multi-drug resistant cells. To surpass that, the use of nanomedicine for the targeted delivery of genetic material, drugs or both have been extensively researched. In this review, we address the current situation of the disorder and some gene therapy options in the nanomedicine field that have been investigated. Among them, polymeric micelles (PM) are an advantageous therapeutic alternative highly explored for OS, as they allow for the targeted transportation of poorly water-soluble drugs to cancer cells. In addition, micelleplexes are PMs with cationic properties with promising features, such as the possibility for a dual therapy, which have made them an attractive research subject. The aim of this review article is to elucidate the application of a micelleplex formulation encapsulating the underexpressed miRNA145 to achieve an active targeting to OS cells and overcome multi-drug resistance, as a new and viable therapeutic strategy.

The therapeutic value of the SphK1-targeting microRNA-3677 in human osteosarcoma cells

Sphingosine kinase 1 (SphK1) is a potential therapeutic target for human osteosarcoma (OS). SphK1-targeting microRNAs (miRNAs) could have important therapeutic value for OS. We discovered that micorRNA-3677 (miR-3677) is a SphK1-targeting miRNA, inhibiting OS cell progression. The results of RNA-Pull down assay confirmed direct binding between biotinylated-miR-3677 and SphK1 mRNA in primary human OS cells. In established and primary human OS cells forced overexpression of miR-3677, by a lentiviral construct, decreased SphK1 3’-UTR (untranslated region) activity and downregulated SphK1 expression. Both were however enhanced with miR-3677 inhibition in OS cells. Function studies demonstrated that OS cell growth, proliferation and migration were inhibited with miR-3677 overexpression, but augmented with miR-3677 inhibition. MiR-3677 overexpression-induced anti-OS cell activity was reversed with re-expression of the 3’-UTR-depleted SphK1. Additionally, in SphK1 knockout OS cells (by CRISPR/Cas9 strategy), altering miR-3677 expression failed to further alter cell functions. Finally, we show that miR-3677 expression was significantly downregulated in primary human OS tissues, correlating with SphK1 mRNA upregulation. We conclude that targeting SphK1 by miR-3677 inhibits human OS cell progression.

MiR-671-5p plays a promising role in restraining osteosarcoma cell characteristics through targeting TUFT1

The aim of our study was to explore the roles of miR-671-5p in mediating biological processes of osteosarcoma (OS) cells and clinical implications. On the basis of the OS samples acquired from the GEO database, the expression difference and overall survival analyses of miR-671-5p and TUFT1 were determined. The expression of MiR-671-5p was verified using OS cell lines. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, wound-healing, and Transwell assays were respectively carried out to probe whether miR-671-5p regulated OS cell vitality, migration, and invasion. The expression of miR-671-5p was downregulated in OS tissues and cell lines. High expression of MiR-671-5p blocked OS cell growth, migration, and invasion. TUFT1 was predicted and validated as the target of miR-671-5p in OS cells using in silico analysis and luciferase reporter assays. Forced expression of TUFT1 reversed the suppressive influence of miR-671-5p on cell viability, migration, and invasion of OS cells. Moreover, the low expression of miR-671-5p and the high expression of TUFT1 led to poor prognosis. Taken together, targeting miR-671-5p/TUFT1 may be a promising strategy for treating OS.

Influence mechanism of miRNA-144 on proliferation and apoptosis of osteosarcoma cells

Influence mechanism of miRNA-144 on proliferation and apoptosis of osteosarcoma cells was investigated. A total of 51 cases of osteosarcoma tissue samples were collected in the department of orthopedic surgery, Xuzhou Children's Hospital, Xuzhou Medical University from January 2014 to February 2017. Additionally, 48 cases of normal bone tissues were collected. qRT-PCR was used to detect the expression of miR-144. Correlation of miR-144 expression in serum and cancer tissues was detected. ROC curve was drawn to analyze the diagnostic value of miR-144 in patients with osteosarcoma. CCK-8 was used to detect the effect of miR-144 on the proliferation ability of U2-OS after transfection. The ratio of U2-OS apoptosis after miR-144 transfection was detected by flow cytometry. Western blot analysis was used to detect the expression of Bax, caspase-3 and Bcl-2 proteins in U2-OS after transfection. The relative expression of miR-144 in osteosarcoma and osteosarcoma serum was significantly lower than that in normal bone tissue and normal human serum (P<0.05). Serum in patients was positively correlated with the expression of miR-144 in cancer tissues. The area under the miR-144 curve was 0.852, 95% CI, 0.768–0.936. The relative expression of miR-144 in MG-63 and U2-OS cells was significantly lower than that in hFOB1.19 cells (P<0.05), while significantly lower in U2-OS cells than in MG-63 cells (P<0.05). Proliferation ability of U2-OS cells transfected with miR-144-mimics was significantly inhibited and the apoptosis rate was significantly increased (P<0.05). Bcl-2 protein was significantly decreased by detection of WB and the expression of Bax and caspase-3 protein was significantly increased (P<0.05). miR-144 may be involved in the occurrence and deterioration of osteosarcoma. miR-144 can regulate proliferation and apoptosis of U2-OS cells. It is expected to become a new diagnostic and index target for osteosarcoma.

miR-193b Increases the Chemosensitivity of Osteosarcoma Cells by Promoting FEN1-Mediated Autophagy

Background

Osteosarcoma (OS) is one of the most common malignant bone tumors and specific microRNAs (miRNAs) are closely associated with malignant OS progression. In this study, we examined the role of microRNA-193b-3p (miR-193b) and the involvement of autophagy and apoptosis in the chemosensitivity of OS cells.

Methods

We employed qRT-PCR, Western blot, and immunohistochemistry to examine the expression levels of miR-193b, flap endonuclease 1 (FEN1), and autophagy-related proteins. Apoptosis was determined by flow cytometry using an Annexin V-FITC/PI apoptosis detection kit. Luciferase reporter assays confirmed the relationship between miR-193b and FEN1.

Results

miR-193b was downregulated in OS compared to adjacent normal tissues (p < 0.05). miR-193b overexpression in the OS cell lines induced autophagy and apoptosis, as shown by Western blotting and flow cytometry. Knockdown of FEN1, a structure-specific nuclease overexpressed in OS tissues (p < 0.001), induced apoptosis through activation of autophagy. Luciferase reporter assays confirmed that FEN1 is a direct target of miR-193b, FEN1 knockdown reinforced miR-193b induced apoptosis. Moreover, miR-193b expression enhanced epirubicin-induced autophagy and apoptosis.

Conclusion

Collectively, the results showed that miR-193b/FEN1 may serve as a novel therapeutic target for OS aimed mainly at the induction of autophagy and apoptosis. The miR-193b/FEN1 axis increased the chemosensitivity of OS cells, while activation of autophagy enhanced the anticancer effects of epirubicin.

Silencing of long-non-coding RNA ANCR suppresses the migration and invasion of osteosarcoma cells by activating the p38MAPK signalling pathway

Background

Osteosarcoma (OS) is a malignancy of the bone that has no clearly identified prognostic factors for diagnosis. In this study, we evaluated the regulatory role of long non-coding RNA (lncRNA) ANCR on the migration and invasion of OS cells as well as the possible mechanism involving the p38MAPK signalling pathway.

Methods

ANCR expression was determined in OS tissues and OS cell lines (MG-63, S1353, U2OS, and UMR-106) by qRT-PCR. It was observed that ANCR was down-regulated in MG-63 and U2OS cells by 48 h of siRNA-ANCR (si-ANCR) transfection. The proliferation of transfected cells was determined using the CCK-8 and the EdU assays. The migration and invasion of transfected cells were determined by the Transwell assay. The expression of E-cadherin, N-cadherin, and phosphorylated p38MAPK (p-p38MAPK) proteins was determined by Western blot. In addition, combinatorial treatment of cells with si-ANCR + SB203580 (p38MAPK inhibitor) was performed to investigate the association between ANCR and MAPK signalling in OS cells.

Results

ANCR was up-regulated in OS cells and tissues. ANCR silencing significantly inhibited the proliferation rate, decreased the percentage of migration and invasion cells, down-regulated N-cadherin, and up-regulated E-cadherin and p-p38MAPK in MG-63 and U2OS cells. Inhibition of the p38MAPK signalling pathway (SB203580) in MG-63 and U2OS cells rescued si-ANCR-induced inhibition of cell migration and invasion.

Conclusions

Silencing of ANCR inhibited the migration and invasion of OS cells through activation of the p38MAPK signalling pathway.

LncRNA SPRY4‑IT1 promotes progression of osteosarcoma by regulating ZEB1 and ZEB2 expression through sponging of miR‑101 activity

Long non‑coding (lnc)RNA sprouty receptor tyrosine kinase signalling antagonist 4‑intronic transcript 1 (SPRY4‑IT1) has been demonstrated to serve a critical role in the tumorigenesis of osteosarcoma (OS); however, the specific underlying mechanism remains unclear. The aim of the present study was to examine the interactions between SPRY4‑IT1 and its downstream effectors, to determine if any of the interactions contributed to SPRY4‑IT1‑mediated proliferation, migration and invasion in cancer cells. A signalling cascade which involved SPRY4‑IT1, miR‑101 and zinc finger E‑box‑binding homeoboxes (ZEBs) was examined in the present study. Intracellular SPRY4‑IT1 and miR‑101 expression levels were altered through transfection to assess their effect on proliferation, cell cycle progression, survival, migration and invasion. A dual‑luciferase assay was utilized to determine the association between SPRY4‑IT1/miR‑101 and ZEBs/miR‑101 and nude mouse xenograft experiments were performed to determine the effect of SPRY4‑IT1 in vivo. The results indicated that the SPRY4‑IT1 levels were negatively associated with miR‑101 expression levels in OS cells, an association which was not observed in the normal osteoblast cells. SPRY4‑IT1 knockdown or miR‑101 overexpression reduced proliferation, cell cycle progression, survival, migration and invasion of MG‑63 and U2OS cells. SPRY4‑IT1 knockdown was accompanied by increased expression of miR‑101 and E‑cadherin levels, as well as decreased expression levels of ZEB1/2 and other epithelial‑mesenchymal transition‑associated proteins. Simultaneous knockdown of SPRY4‑IT1 and inhibition of miR‑101 partially reversed the anti‑tumour effects of SPRY4‑IT1 inhibition in vitro. Consistent with these findings, short hairpin RNA targeting SPRY4‑IT1 also hindered xenograft tumour growth and altered the levels of miR‑101, ZEB1/2 and E‑cadherin in vivo. Dual‑luciferase reporter assays demonstrated that SPRY4‑IT1 may have regulated the expression of ZEB1 and ZEB2 by sponging miR‑101. In conclusion, SPRY4‑IT1 inhibition increased miR‑101 levels, resulting in downregulation of ZEB1/2 expression and thus exerting anti‑tumour effects in OS.

The Role of miRNA in the Diagnosis, Prognosis, and Treatment of Osteosarcoma

Osteosarcoma (OS) is one of the most common malignant tumors derived from mesenchymal tissue and is highly invasive, mainly in children and adolescents. Treatment of OS is mostly based on standard treatment options, including aggressive surgical resection, systemic chemotherapy, and targeted radiation therapy, but the 5-year survival rate is still low. MicroRNA (miRNA) is a highly conserved type of endogenous nonprotein-encoding RNA, about 19-25 nucleotides in length, whose transcription process is independent of other genes. Generally, miRNAs play a role in regulating cell proliferation, differentiation, apoptosis, and development by binding to the 3' untranslated region of target mRNAs, whereby they can degrade or induce translational silencing. Although miRNAs play a regulatory role in various metabolic processes, they are not translated into proteins. Several studies have shown that miRNAs play an important role in the diagnosis, treatment, and prognosis of OS. Herein, the authors describe new advances in the diagnosis, prognosis, and treatment of miRNAs in OS.

MicroRNA-1296-5p suppresses the proliferation, migration, and invasion of human osteosarcoma cells by targeting NOTCH2

Osteosarcoma (OS) is a highly aggressive bone tumor with a poor prognosis. MicroRNAs are revealed to exerts essential roles in the carcinogenesis and tumor invasion of OS. But, the function of miR-1296-5p and its related mechanism in OS progression have not yet been studied. This study discovered the levels of miR-1296-5p in OS and corresponding noncancerous tissues, and we demonstrated that miR-1296-5p level was markedly downregulated in tumor specimens as compared with nontumor tissues. In addition, we discovered that miR-1296-5p was also underexpressed in OS cells compared with the hFOB1.19 osteoblast cells. Interestingly, the reduced expression of miR-1296-5p was confirmed to associated with large tumor size, advanced tumor stages, and distance metastasis, respectively. Patients with OS low-expressing miR-1296-5p showed a prominent shorter survival. In addition, gain-of-function assays verified that miR-1296-5p overexpression remarkably repressed OS cell proliferation, migration, and invasion. Conversely, depletion of miR-1296-5p facilitated the growth and mobility of OS cells. Notably, miR-1296-5p inversely modulated notch receptor 2 (NOTCH2) in OS cells. The level of NOTCH2 messenger RNA was negatively correlated with miR-1296-5p level in OS samples. NOTCH2 knockdown markedly suppressed the abilities of MG-63 cell proliferation and mobility. More importantly, the restoration of NOTCH2 prominently rescued miR-1296-5p-induced tumor-suppressive effects on MG-63 cells. In conclusion, our study identified the reduced expression of miR-1296-5p, which contributed to OS progression. miR-1296-5p might be a promising prognostic marker and therapeutic target in OS.

MicroRNA-29a suppresses the invasion and migration of osteosarcoma cells by regulating the SOCS1/NF-κB signalling pathway through negatively targeting DNMT3B

The present study aimed to investigate the roles of the microRNA‑29a/DNA methyltransferase 3B/suppressor of cytokine signalling 1 (miR‑29a/DNMT3B/SOCS1) axis in the invasion and the migration of osteosarcoma (OS). The expression levels of miR‑29a, DNMT3B and SOCS1 were determined in tissue samples and OS cell lines by reverse transcription‑quantitative polymerase chain reaction (PCR). Apoptosis was measured using flow cytometry analysis. Transwell and wound healing assays were conducted to measure the invasion and migration abilities of OS cells, respectively. A dual‑luciferase reporter assay was also conducted to determine the interaction between DNMT3B and miR‑29a, while methylation‑specific PCR was used to detect the methylation of SOCS1. Western blotting was performed to determine the protein levels of DNMT3B and SOCS1, as well as the levels of proteins associated with epithelial‑mesenchymal transition (EMT), apoptosis and the nuclear factor (NF)‑κB signalling pathway. The results demonstrated that miR‑29a and SOCS1 were downregulated, and DNMT3B was upregulated in both OS tissues and cell lines. The expression of miR‑29a and SOCS1 was found to be associated with advanced clinical stage and distant metastasis. In addition, the dual‑luciferase reporter assay revealed that DNMT3B was a direct target of miR‑29a. Overexpression using miR‑29a mimics decreased DNMT3B expression and the methylation level of SOCS1, which resulted in the upregulation of SOCS1 in U2OS and MG‑63 cells, while miR‑29a inhibition led to the opposite results. Transfection with miR‑29a mimics also promoted the apoptosis, and inhibited the invasion, migration and EMT process of OS cells, while it markedly reduced the nuclear translocation of p65 and IκB‑α degradation. Treatment with 5‑aza‑2'‑deoxycytidine worked together with miR‑29a mimics to synergistically enhance the aforementioned effects. By contrast, the effects induced by miR‑29a were partly reversed upon co‑transfection with SOCS1 siRNA. In conclusion, miR‑29a promoted the apoptosis, and inhibited the invasion, migration and EMT process of OS cells via inhibition of the SOCS1/NF‑κB signalling pathway by directly targeting DNMT3B.

Identification and validation of microRNAs and their targets expressed in osteosarcoma

Osteosarcoma (OS) is the most common type of bone cancer in children and adolescents, and has a poor prognosis. Previous studies have demonstrated that a number of microRNAs (miRNAs) were deregulated in OS, and that the expression of certain miRNAs was correlated with the stage of OS. Therefore, miRNAs may serve a role as a diagnostic and prognostic biomarker of OS. miRNA and mRNA integrated analysis of public expression profiles in the Gene Expression Omnibus database for OS was performed, and the regulated targets of miRNA in OS were predicted. Next, the regulatory network of miRNAs/genes was constructed and verified by reverse transcription-quantitative polymerase chain reaction in tissues and MG-63 cell lines. Two miRNA expression profiling studies and four eligible mRNA expression profiling studies were selected. Ten upregulated miRNAs, 5 downregulated miRNAs and 5 DGEs were identified in OS compared with normal tissues. hsa-miR-346 was inversely correlated with the target gene c-FLIP, which was consistent with the results of integrated analysis. In vitro, pre-miRNA-346 can downregulate the protein expression of c-FLIP, while not changing the mRNA level of c-FLIP. In the regulatory network, hsa-miR-346 and its target gene, c-FLIP, can be used as biomarkers for an earlier diagnosis of OS.

miR‑185 regulates the growth of osteosarcoma cells via targeting Hexokinase 2

MicroRNAs (miRNAs) have been proposed as potential prognostic and diagnostic biomarkers in numerous types of cancer, including osteosarcoma (OS), which is the most common bone malignancy. The present study revealed that the expression of miR‑185 was downregulated in OS tissues and cells. Overexpression of miR‑185 significantly suppressed the proliferation and migration of OS cells. To further investigate the functional roles of miR‑185 in OS, the downstream targets of miR‑185 were predicted using the microRNA.org database. The results revealed that in cancer cells, hexokinase 2 (HK2), the rate‑limiting enzyme of glycolysis, was a potential target of miR‑185. Molecular analysis indicated that miR‑185 binds to the 3'‑untranslated region of HK2 mRNA. Overexpressed miR‑185 downregulated the mRNA and protein levels of HK2 in OS cells. In addition, an inverse correlation between the expression of miR‑185 and HK2 was reported in OS. Consistent with the downregulation of HK2 induced by miR‑185, overexpression of HK2 in OS cells significantly attenuated the inhibitory effects of miR‑185 on glucose consumption and lactate production, while depletion of miR‑185 promoted the glycolysis of OS cells. Additionally, restoration of HK2 abolished the inhibitory effects of miR‑185 on the proliferation of OS cells. In summary, these results revealed that miR‑185 suppressed the glucose metabolism of OS cells; thus, miR‑185 may be considered as a promising therapeutic target for the treatment of OS.