MicroRNAs and Potential Targets in Osteosarcoma: Review

MicroRNA-152 Suppresses Human Osteosarcoma Cell Proliferation and Invasion by Targeting E2F Transcription Factor 3

MicroRNA-152 (miR-152) expression has been reported to be downregulated in osteosarcoma (OS). However, the role of miR-152 in OS is not well documented. In the present study, we aimed to explore the function and underlying mechanism of miR-152 in OS. We found that miR-152 was underexpressed in OS tissues and cell lines. Decreased miR-152 was inversely correlated with lymph node metastasis and advanced clinical stage. Overexpression of miR-152 significantly inhibited cell proliferation, colony formation, migration, and invasion of OS cells. Bioinformatics analyses showed that miR-152 directly targeted E2F transcription factor 3 (E2F3), as further confirmed by a dual-luciferase reporter assay. E2F3 expression was upregulated and inversely correlated with miR-152 expression level in human OS tissues. Moreover, the inhibitory effects of miR-152 on OS growth and invasion were attenuated by E2F3 overexpression. Taken together, our findings indicated that miR-152 reduced OS growth and invasion by targeting E2F3 and provided new evidence of miR-152 as a potential therapeutic target for OS.

Biological analysis of cancer specific microRNAs on function modeling in osteosarcoma

Osteosarcoma (OS) is the most common bone tumor characterized with a high risk of amputation and malignant morbidity among teenagers and adolescents. However, relevant pathogenic/biological mechanisms underlying OS-genesis remains to be ambiguous. The aim of this study was to elucidate functional relationship about microRNAs-mRNAs networks and to identify potential molecular markers via a computational method. Gene expression profile (GSE70415) was recruited from Gene Expression Omnibus. 3856 differentially expressed genes and 250 significantly expressed microRNAs were identified by using GCBI. The results of GO and KEGG pathways associated proteomics analysis indicated that extracellular matrix organization, small molecule metabolic process, cell adhesion (GO IDs: 0030198, 0044281, 0007155) and pathways in cancer, PI3K-Akt signaling pathway, metabolic pathways (pathway IDs: 5200, 4151, 1100) were significantly enriched. In addition, CKMT2, miR-93b-5p, miR-29b-3p were found to be positively/negatively correlated with TP53, EGFR, and MMP members mediated OS development, including angiogenesis, migration and invasion. Further visualization of collective effect of 1181 microRNAs-mRNAs pairs and protein-protein interactions was realized by applying with cytosacpe. In summary, our work provided a better understanding of non-coding regulatory mechanisms of transcriptomics and unraveled essential molecular biomarkers in osteosarcoma.

The Microtubule Network and Cell Death Are Regulated by an miR-34a/Stathmin 1/βIII-Tubulin Axis

MicroRNA-34a (miR-34a) is a master regulator of signaling networks that maintains normal physiology and disease and is currently in development as a miRNA-based therapy for cancer. Prior studies have reported low miR-34a expression in osteosarcoma; however, the molecular mechanisms underlying miR-34a activity in osteosarcoma are not well-defined. Therefore, this study evaluated the role of miR-34a in regulating signal transduction pathways that influence cell death in osteosarcoma. Levels of miR-34a were attenuated in human osteosarcoma cells and xenografts of the Pediatric Preclinical Testing Consortium (PPTC). Bioinformatics predictions identified stathmin 1 (STMN1) as a potential miR-34a target. Biotin pull-down assay and luciferase reporter analysis confirmed miR-34a target interactions within the STMN1 mRNA 3'-untranslated region. Overexpression of miR-34a in osteosarcoma cells suppressed STMN1 expression and reduced cell growth in vitro Restoration of miR-34a led to microtubule destabilization and increased βIII-tubulin expression, with corresponding G1-G2 phase cell-cycle arrest and apoptosis. Knockdown of the Sp1 transcription factor, by siRNA silencing, also upregulated βIII-tubulin expression in osteosarcoma cells, suggesting that miR-34a indirectly affects Sp1. Validating the coordinating role of miR-34a in microtubule destabilization, when miR-34a was combined with either microtubule inhibitors or chemotherapy, STMN1 phosphorylation was suppressed and there was greater cytotoxicity in osteosarcoma cells. These results demonstrate that miR-34a directly represses STMN1 gene and protein expression and upregulates βIII-tubulin, leading to disruption of the microtubule network and cell death.Implications: The miR-34a/STMN1/βIII-tubulin axis maintains the microtubule cytoskeleton in osteosarcoma, and combining miR-34a with microtubule inhibitors can be investigated as a novel therapeutic strategy. Mol Cancer Res; 15(7); 953-64. ©2017 AACR.

MicroRNA-25 suppresses proliferation, migration, and invasion of osteosarcoma by targeting SOX4

Altered expression of the miR-25 has been implicated in many human malignant progression as oncogene or tumor suppressor. However, the precise role of miR-25 in osteosarcoma progression remains largely unclear. This study aimed to investigate the role and underlying mechanism of miR-25 in osteosarcoma. In this study, we demonstrated that miR-25 was significantly downregulated in osteosarcoma cell lines and tissues and that lower miR-25 was associated with advanced tumor-node-metastasis stage and lymph node metastasis. Then, we found that introduction of miR-25 significantly suppressed the proliferation, colony formation, migration, and invasion of osteosarcoma cells in vitro and retarded tumor growth in vivo. Further studies indicated that the epithelial-mesenchymal transition-related transcription factor, SOX4 (SRY-related high-mobility group box 4), was a direct target gene of miR-25, evidenced by bioinformatics analysis predicted and luciferase reporter assay. Furthermore, miR-25 could decrease the expression of SOX4 levels and inhibited epithelial-mesenchymal transition process. The levels of miR-25 were inversely correlated with those of SOX4 expression in osteosarcoma tissues. SOX4 overexpression rescued miR-25-induced suppression of proliferation, migration, and invasion of osteosarcoma cells. Taken together, these results suggest that miR-25 functions as a tumor suppressor in the progression of osteosarcoma by repressing SOX4.

Genome-Wide Scleral Micro- and Messenger-RNA Regulation During Myopia Development in the Mouse

Purpose

MicroRNA (miRNAs) have been previously implicated in scleral remodeling in normal eye growth. They have the potential to be therapeutic targets for prevention/retardation of exaggerated eye growth in myopia by modulating scleral matrix remodeling. To explore this potential, genome-wide miRNA and messenger RNA (mRNA) scleral profiles in myopic and control eyes from mice were studied.

Methods

C57BL/6J mice (n = 7; P28) reared under a 12L:12D cycle were form-deprived (FD) unilaterally for 2 weeks. Refractive error and axial length changes were measured using photorefraction and 1310-nm spectral-domain optical coherence tomography, respectively. Scleral RNA samples from FD and fellow control eyes were processed for microarray assay. Statistical analyses were performed using National Institute of Aging array analysis tool; group comparisons were made using ANOVA, and gene ontologies were identified using software available on the Web. Findings were confirmed using quantitative PCR in a separate group of mice (n = 7).

Results

Form-deprived eyes showed myopic shifts in refractive error (−2.02 ± 0.47 D; P < 0.01). Comparison of the scleral RNA profiles of test eyes with those of control eyes revealed 54 differentially expressed miRNAs and 261 mRNAs fold-change >1.25 (maximum fold change = 1.63 and 2.7 for miRNAs and mRNAs, respectively) (P < 0.05; minimum, P = 0.0001). Significant ontologies showing gene over-representation (P < 0.05) included intermediate filament organization, scaffold protein binding, detection of stimuli, calcium ion, G protein, and phototransduction. Significant differential expression of Let-7a and miR-16-2, and Smok4a, Prph2, and Gnat1 were confirmed.

Conclusions

Scleral mi- and mRNAs showed differential expression linked to myopia, supporting the involvement of miRNAs in eye growth regulation. The observed general trend of relatively small fold-changes suggests a tightly controlled, regulatory mechanism for scleral gene expression.

DNA Methylation Mediated Down-Regulation of miR-370 Regulates Cell Growth through Activation of the Wnt/β-Catenin Signaling Pathway in Human Osteosarcoma Cells

MicroRNA-370 (miR-370) has been observed to act as a tumor suppressor through the targeting of different proteins in a variety of tumors. Our previous study indicated that miR-370 was able to target forkhead box protein M1 (FOXM1) to inhibit cell growth and metastasis in human osteosarcoma cells. In this study, we reported that FOXM1 interacted with β-catenin in vitro and in vivo. Similar to FOXM1, critical components of the Wnt signaling pathway, including β-catenin, c-Myc, and Cyclin D1, were also highly expressed in different human osteosarcoma cells lines. Pharmacological inhibition of FOXM1 or β-catenin but not of c-Myc was associated with the increased expression of miR-370. Ectopic expression of miR-370 inhibited the downstream signaling of β-catenin. Moreover, osteosarcoma cells treated with 5-AZA-2'-deoxycytidine (AZA), a DNA methylation inhibitor, exhibited increased levels of miR-370 and decreased levels of β-catenin downstream targets, which resulted in inhibition of cell proliferation and colony formation ability. In conclusion, our results supported a model in which the DNA methylation-mediated down-regulation of miR-370 reduced its inhibitory effect on FOXM1, thereby promoting FOXM1-β-catenin interaction and activating the Wnt/β-Catenin signaling pathway in human osteosarcoma cells.

Genetic polymorphisms in ERCC1 and ERCC2 genes are associated with response to chemotherapy in osteosarcoma patients among Chinese population: a meta-analysis

BACKGROUND

There existed controversies about the association between the response to chemotherapy for osteosarcoma (OS) patients and the genetic polymorphisms in excision repair cross-complementation group (ERCC1 and ERCC2) genes. We aimed to perform a meta-analysis to comprehensively evaluate the association.

METHOD

We searched multiple databases for literature retrieval including the PubMED (1966 ∼ 2017), Embase (1980 ∼ 2017), and the Web of science (1945 ∼ 2017). The overall odds ratios(OR) and their corresponding 95% confidence interval (CI) were calculated for the three polymorphisms under the dominant, recessive, and allelic models.

RESULTS

From six eligible articles in our study, we found that for ERCC1 rs11615 polymorphism, a significant association was detected between the chemotherapy response and the polymorphism under all three models (dominant model: OR = 2.015, P = 0.005; recessive model: OR = 1.791, P = 0.003; allelic model: OR = 1.677, P = 0.003), and OS patients carrying C allele in rs11615 polymorphism were more likely to response to chemotherapy. In terms of ERCC2 rs1799793 polymorphism, this polymorphism was significantly associated with the response to chemotherapy for OS patients under recessive model (OR = 1.337, P = 0.036), and patients with AG + AA genotype in rs1799793 polymorphism were more appropriate to receive chemotherapy. With respect to ERCC2 rs13181 polymorphism, this polymorphism was not correlated with the response to chemotherapy for OS patients under all three models.

CONCLUSIONS

Our meta-analysis suggested that among Chinese population, the rs11615 and rs1799793 polymorphisms were significantly correlated with the response to chemotherapy for patients with OS, and patients with CC or TC + CC genotypes in ERCC1 rs11615 polymorphism or AG + AA genotype in ERCC2 rs1799793 polymorphism were more suitable for chemotherapy.

MicroRNA-342-3p Inhibits the Proliferation, Migration, and Invasion of Osteosarcoma Cells by Targeting Astrocyte-Elevated Gene-1 (AEG-1)

Recent studies suggest that microRNAs (miRNAs) are critical regulators in many types of cancer, including osteosarcoma. miR-342-3p has emerged as an important cancer-related miRNA in several types of cancers. However, the functional significance of miR-342-3p in osteosarcoma is unknown. The aims of this study were to investigate whether miR-342-3p is dysregulated in osteosarcoma and to explore the biological function of miR-342-3p in regulating cellular processes of osteosarcoma cells. We found that miR-342-3p expression was significantly decreased in osteosarcoma tissues and cell lines. Overexpression of miR-342-3p inhibits the proliferation, migration, and invasion of osteosarcoma cells. In contrast, the inhibition of miR-342-3p exhibited the opposite effect. Astrocyte-elevated gene-1 (AEG-1) was identified as one of the target genes of miR-342-3p in osteosarcoma cells by bioinformatics analysis, dual-luciferase reporter assay, real-time quantitative polymerase chain reaction, and Western blot analysis. Overexpression of miR-342-3p also inhibited the Wnt and nuclear factor κB signaling pathways. Moreover, overexpression of AEG-1 partially rescued the inhibitory effects of miR-342-3p mediated on the proliferation, migration, and invasion of osteosarcoma cells. Overall, our results show that miR-342-3p inhibits the proliferation, migration, and invasion of osteosarcoma cells through targeting AEG-1, suggesting a potential target for the development of miRNA-based therapy for osteosarcoma.

Advances in Bone-targeted Drug Delivery Systems for Neoadjuvant Chemotherapy for Osteosarcoma

Targeted therapy for osteosarcoma includes organ, cell and molecular biological targeting; of these, organ targeting is the most mature. Bone-targeted drug delivery systems are used to concentrate chemotherapeutic drugs in bone tissues, thus potentially resolving the problem of reaching the desired foci and minimizing the toxicity and adverse effects of neoadjuvant chemotherapy. Some progress has been made in bone-targeted drug delivery systems for treatment of osteosarcoma; however, most are still at an experimental stage and there is a long transitional period to clinical application. Therefore, determining how to combine new, polymolecular and multi-pathway targets is an important research aspect of designing new bone-targeted drug delivery systems in future studies. The purpose of this article was to review the status of research on targeted therapy for osteosarcoma and to summarize the progress made thus far in developing bone-targeted drug delivery systems for neoadjuvant chemotherapy for osteosarcoma with the aim of providing new ideas for highly effective therapeutic protocols with low toxicity for patients with osteosarcoma.

miR-204-5p acts as a tumor suppressor by targeting matrix metalloproteinases-9 and B-cell lymphoma-2 in malignant melanoma

An increasing number of microRNAs have been found to be involved in tumorigenesis, including melanoma tumorigenesis. miR-204-5p is down-regulated and functions as a tumor suppressor in many human malignant tumors. miR-204-5p expression is also decreased in melanoma tissues, but its biological roles and molecular mechanisms in malignant melanoma remain unclear. In this study, the aberrant down-regulation of miR-204-5p was detected in melanoma, especially in metastatic melanoma. miR-204-5p also served as a protective factor for the prognosis of melanoma patients. We determined that miR-204-5p suppresses cell proliferation, migration and invasion, and promotes cell apoptosis in melanoma. Matrix metalloproteinases-9 and B-cell lymphoma-2 are the functional targets of miR-204-5p, through which it plays an important biological role in malignant melanoma. The effect of miR-204-5p on malignant melanoma is verified using a xenograft model. We also determined that miR-204-5p increases 5-fluorouracil and cisplatin (DDP) chemosensitivity in malignant melanoma cells. This finding elucidates new functions and mechanisms for miR-204-5p in melanoma development, and provides potential therapeutic targets for the treatment of melanoma.

Overexpression of miR‑214 promotes the progression of human osteosarcoma by regulating the Wnt/β‑catenin signaling pathway

The aberrant expression of microRNA (miR)‑214 contributes to the regulation of normal and cancer cell biology, and is associated with human malignancies, however, it can operate in a contradictory manner. The role of miR‑214 in osteosarcoma remains to be fully elucidated. The aim of the present study was to investigate the effects of miR‑214 on osteosarcoma progression and tumor cell proliferation, and examine the molecular mechanism underlying osteosarcoma. The level of miR‑214 was determined using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) analysis in osteosarcoma and matched paracancerous tissues, and in human osteosarcoma cancer cell lines. The roles of miR‑214 in cell proliferation, survival and cell cycle were analyzed using miR‑214 lentivirus (LV‑miR‑214)‑infected osteosarcoma cells. In addition, the downstream target proteins in the Wnt/β‑catenin signaling pathway were evaluated using western blot analysis in the LV‑miR‑214‑infected cells. The LV‑miR‑214‑infected MG63 cells were also treated with exogenous β‑catenin for 24, 48 and 72 h, respectively, following which the expression of β‑catenin was measured using western blot analysis and survival was determined using a 3‑(4,5‑cimethylthiazol‑2‑yl)‑2,5‑diphenyl tetrazolium bromide (MTT) assay. The results of the RT‑qPCR analysis showed that the expression level of miR‑214 was significantly higher in the osteosarcoma tissues, compared with that in the matched paracancerous tissues, and the same was observed in the osteosarcoma cell lines. The MG63, Saos‑2 and U2OS cells were infected with the hsa‑mir‑214 lentivirus for 48 h, and the levels of miR‑214 were significantly upregulated in the human osteosarcoma cancer cells. The overexpression of miR‑214 in the MG‑63 and Saos‑2 cells promoted cell growth, and treatment of the cells with specific antisense‑microRNA oligonucleotides (AMOs) for miR‑214 for indicated durations reversed the effects of miR‑214. Additionally, the AMO‑treated MG63 cells showed G0/G1 phase arrest, suggesting that miR‑214 contributed to regulation of the cell cycle. In addition, the results of western blot analysis showed that, in the miR‑214 lentivirus‑infected cells, the levels of cyclin‑D1, c‑myc and lymphoid enhancer‑binding factor‑1 were significantly increased, compared with those in the control lentivirus‑infected cancer cells. Of note, infection with the miR‑214 lentivirus did not affect the levels of Wnt1, Wnt2, Wnt4, Axin or glycogen synthase kinase β in the U2OS cells, whereas the expression levels of β‑catenin in the MG63 cells and Saos‑2 cells were significantly increased. The addition of exogenous β‑catenin effectively reversed the efficiency of miR‑214‑specific AMOs, which was detected using an MTT assay. These data suggested the critical role of miR‑214 in human osteosarcoma via regulation of the Wnt/β‑catenin signaling pathway and demonstrated that miR‑214 is as an oncogene for human osteosarcoma.

Decreased Expression of miR-548c-3p in Osteosarcoma Contributes to Cell Proliferation Via Targeting ITGAV

The members of the integrin αv (ITGAV) family are widely expressed on many types of tumors and have been reported to be involved into angiogenesis, tumor metastases, and multicellular radioresistance. Osteosarcoma (OS) is the most common primary malignant bone tumor and the role of ITGAV in OS needs to be further elucidated. MicroRNAs are aberrantly expressed in a variety of cancers. Thus, the authors collected OS tissues (n = 15) and corresponding paracancerous tissues (n = 15) and found that the expression of miR-548c-3p was significantly downregulated in OS tissues and cell lines 143B, SaoS2, and HOS when compared to the corresponding paracancerous tissues and human osteoblast cell line hFOB (OB3), respectively. In addition, the authors identified that miR-548c-3p could directly target the 3'-untranslated region of ITGAV, and miR-548c-3p overexpression inhibits the mRNA and protein levels of ITGAV, which were confirmed by the luciferase reporter assays. Interestingly, they also uncovered that miR-548c-3p overexpression or knockdown of ITGAV remarkably suppressed cell vitality and promoted apoptosis and G2/M cell cycle arrest, leading to abrogating the ability of colony formation. The results indicated that the miR-548c-3p, similar to the target agents against integrin αv in clinical trials, could negatively regulate the ITGAV and be a promising tumor therapeutic target.

Overexpression of miR-92a promotes the tumor growth of osteosarcoma by suppressing F-box and WD repeat-containing protein 7

MicroRNAs (miRNAs) have been reported to be critical players in osteosarcoma (OS). Among numerous cancer-related miRNAs, the expression level of miR-92a and its potential role in OS has not been investigated. Here, We showed that overexpression of miR-92a was identified in OS specimens and cells compared to normal bone tissues. The high level of miR-92a was correlated with high T classification and advanced clinical stages of OS patients. Notably, miR-92a highly expressing OS patients showed a notably reduced survival rate. In vitro experiments showed that loss of miR-92a inhibited U2OS cell proliferation and cell-cycle progression while induced apoptosis. In turn, its restoration facilitated MG-63 cell growth and suppressed apoptosis. Experimental nude mice showed that miR-92a silencing prohibited the in vivo growth of OS cells. Furthermore, bioinformatics software predicted that F-box and WD repeat-containing protein 7 (FBXW7) was a direct target of miR-92a. We then observed the negative regulation of miR-92a on FBXW7 expression and the direct binding between them was further verified by dual-luciferase assays in OS cells. Forced expression of FBXW7 resulted in reduced proliferation, cell cycle arrest at G1 phase and increased apoptosis in miR-92a overexpressing MG-63 cells. In summary, this study demonstrates miR-92a probably functions as a driver of tumor progression by targeting FBXW7, and highlights the potential effects of miR-92a on prognosis and treatment of OS.

MicroRNA-101 inhibits proliferation, migration and invasion in osteosarcoma cells by targeting ROCK1

Osteosarcoma is a rare malignant bone tumor in adolescents, with high degree of malignancy, and highly incidence of recurrence and metastasis. Our study aimed to explore the role of miR-101 in osteosarcoma cells by targeting ROCK1. In the present study, reverse transcription-quantitative polymerase chain reaction data revealed that miR-101 was down-regulated in the tissue samples of 20 patients with osteosarcoma compared with their matched adjacent non-tumor tissues (P < 0.01). Furthermore, miR-101 was significantly down-regulated in three common OS cell lines, MG63, U2OS, and OS732 compared with the human osteoblast cell line, hFOB1.19 (P < 0.01). MiR-101 was shown to target the ROCK1 3'-UTR in dual-luciferase reporter assays in MG63 cells. Overexpression of miR-101 significantly suppressed the protein expression levels of ROCK1, while knockdown of miR-101 significantly enhanced the formers' expression levels in MG63 cells (P < 0.05). Overexpression of miR-101 inhibited cell viability, migration, and invasion while promoted apoptosis. Independent inhibition of ROCK1 and knockdown of miR-101 expression levels significantly promoted MG63 cell proliferation, migration and invasion while inhibited apoptosis (P < 0.01). Moreover, knockdown of ROCK1 reversed the promotion effect of miR-101 knockdown on proliferation, migration, and invasion while promoted apoptosis of MG63 cells, suggesting that miR-101 acts as a tumor suppressor in osteosarcoma cells via targeting ROCK1. Furthermore, overexpression of miR-101 inhibited tumor growth and motion by inactivating PI3K/AKT and JAK/STAT signaling pathways via downregulation of ROCK1. To conclude, miR-101/ROCK1 may be a potential therapeutic target for osteosarcoma therapy.

MicroRNA-187 exerts tumor-suppressing functions in osteosarcoma by targeting ZEB2

MicroRNA-187 (miR-187) has been reported to be involved in the occurrence and development of several types of cancers; however, a role for miR-187 in osteosarcoma (OS) has not yet been reported. Here, miR-187 was found to be significantly downregulated in OS cell lines and tissue samples, and decreased miR-187 expression was shown to be correlated closely with the TNM stage and lymph node metastasis. miR-187 overexpression suppressed OS cell proliferation, colony formation, migration, invasion, and epithelial-mesenchymal transition (EMT). Mechanically, zinc finger E-box binding homeobox 2 (ZEB2) was shown to serve as a direct target of miR-187 in OS cells and the overexpression of ZEB2 rescued the miR-187-induced suppression of proliferation, colony formation, migration, and invasion in OS cells. In clinical OS specimens, ZEB2 expression levels were elevated and were inversely correlated with miR-187 expression. These results suggest that miR-187 functions as a tumor suppressor in OS, partially by targeting ZEB2, and that miR-187 can serve as a promising candidate for OS.

MicroRNA-613 suppresses proliferation, migration and invasion of osteosarcoma by targeting c-MET

MicroRNA-613 (miR-613) has been reported to play an important role in the pathogenesis of multiple cancers by negatively regulating gene expression at posttranscriptional level. However, the biological role of miR-613 in osteosarcoma (OS) remained unclear. In this study, we aimed to determine the expression and biological roles of miR-613 in OS. We found that miR-613 was significantly downregulated in OS tissues and cell lines, and that decreased miR-613 expression was correlated negatively with advanced TNM stage and lymph node metastasis. Overexpression of miR-613 in OS cells significantly suppressed the proliferation and colony formation by regulating cell arrest at G0/G1 phase, and impaired the migration and invasive abilities of OS cells, followed by suppression of the epithelial mesenchymal transition (EMT). Bioinformatic and luciferase reporter analysis identified cellular-mesenchymal to epithelial transition factor (c-MET, also named as MET) as a direct target of miR-613. Overexpression of miR-613 significantly inhibited the c-MET expression and its downstream PI3k/Akt/mTOR signaling pathway in OS cells. In OS clinical samples, there was a significant inverse correlation between miR-613 and c-MET mRNA expression. Rescue experiments showed that overexpression of c-MET partially prevented miR-613-induced suppression of OS cell proliferation, colony formation, migration and invasion. In conclusion, we provide first evidence for the suppressive activity of miR-613 by repressing c-MET, suggesting that miR-613 might be a potential therapeutic strategy for OS.

miR-15b modulates multidrug resistance in human osteosarcoma in vitro and in vivo

The development of multidrug resistance (MDR) in cancer cells to chemotherapy drugs continues to be a major clinical problem. MicroRNAs (miRNA, miR) play an important role in regulating tumour cell growth and survival; however, the role of miRs in the development of drug resistance in osteosarcoma cells is largely uncharacterized. We sought to identify and characterize human miRs that act as key regulators of MDR in osteosarcoma. We utilized a miR microarray to screen for differentially expressed miRs in osteosarcoma MDR cell lines. We determined the mechanisms of the deregulation of expression of miR-15b in osteosarcoma MDR cell lines, and its association with clinically obtained tumour samples was examined in tissue microarray (TMA). The significance of miR-15b in reversing drug resistance was evaluated in a mouse xenograft model of MDR osteosarcoma. We identified miR-15b as being significantly (P < 0.01) downregulated in KHOS_MR and U-2OS_MR cell lines as compared with their parental cell lines. We found that Wee1 is a target gene of miR-15b and observed that transfection with miR-15b inhibits Wee1 expression and partially reverses MDR in osteosarcoma cell lines. Systemic in vivo administration of miR-15b mimics sensitizes resistant cells to doxorubicin and induces cell death in MDR models of osteosarcoma. Clinically, reduced miR-15b expression was associated with poor patient survival. Osteosarcoma patients with low miR-15b expression levels had significantly shorter survival times than patients with high expression levels of miR-15b. These results collectively indicate that MDR in osteosarcoma is associated with downregulation of miR-15b, and miR-15b reconstitution can reverse chemotherapy resistance in osteosarcoma.

Overexpression of miR-422a inhibits cell proliferation and invasion, and enhances chemosensitivity in osteosarcoma cells

Osteosarcoma (OS) is an aggressive malignant tumor that is mesenchymal in origin with a very low 5-year survival rate, particularly in the patients with locally advanced or metastatic tumors and recurrent disease. MicroRNAs (miRNAs) play a critical role in essential biological processes as cellular proliferation, differentiation and apoptosis in normal or cancer cells, including OS cells. In the present study, we aimed to investigate the role of miR-422a in OS. We demonstrated that miR-422a expression was significantly downregulated in OS tissues and cell lines compared with the normal controls. In addition, overexpression of miR-422a was able to inhibit cell proliferation and the ability of invasion, and enhance paclitaxel and cisplatin-mediated apoptosis in OS cells. Inversely, downregulation of miR-422a exhibited an opposite role. We further demonstrated that miR-422a directly targeted TGFβ2 and regulated its expression and the activation of downstream molecules, smad2 and smad3 in OS cells. Thus, miR-422a/TGFβ2/smad axis may be a potential target for OS treatment.

Clinical Decision Making: Integrating Advances in the Molecular Understanding of Spine Tumors

STUDY DESIGN

Literature review.

OBJECTIVE

To describe advancements in molecular techniques, biomarkers, technology, and targeted therapeutics and the potential these modalities hold to predict treatment paradigms, clinical outcomes, and/or survival in patients diagnosed with primary spinal column tumors.

SUMMARY OF BACKGROUND DATA

Advances in molecular technologies and techniques have influenced the prevention, diagnosis, and overall management of patients diagnosed with cancer. Assessment of genomic, proteomic alterations, epigenetic, and posttranslational modifications as well as developments in diagnostic modalities and targeted therapeutics, although the best studied in nonspinal metastatic disease, have led to increased understanding of spine oncology that is expected to improve patient outcomes. In this manuscript, the technological advancements that are expected to change the landscape of spinal oncology are discussed with a focus on how these technologies will aid in clinical decision-making for patients diagnosed with primary spinal tumors.

METHODS

A review of the literature was performed focusing on studies that integrated next-generation sequencing, circulating tumor cells/circulating tumor DNA, advances in imaging modalities and/or radiotherapy in the diagnosis and treatment of cancer.

RESULTS

We discuss genetic and epigenetic drivers, aberrations in receptor tyrosine kinase signaling, and emerging therapeutic strategies that include receptor tyrosine kinase inhibitors, immunotherapy strategies, and vaccine-based cancer prevention strategies.

CONCLUSION

The wide range of approaches currently in use and the emerging technologies yet to be fully realized will allow for better development of rationale therapeutics to improve patient outcomes.

LEVEL OF EVIDENCE

N/A.

Overexpression of miR-140 Inhibits Proliferation of Osteosarcoma Cells via Suppression of Histone Deacetylase 4

miRNAs play a pivotal role in the development and progression of osteosarcoma (OS). Previous studies indicated that miR-140 acts as a tumor suppressor in many cancers. However, its accurate expression and exact function in OS cells remain unknown. Herein, we demonstrated the lower expression of miR-140 in 40 paired OS tissues. Restoring miR-140 expression in OS cells had a marked effect on inhibiting cell proliferation and invasion, inducing cell apoptosis in vitro, and suppressing tumor growth in vivo. Moreover, a bioinformatics prediction indicated that the histone deacetylase 4 (HDAC4) is a target gene of miR-140 and is involved in miR-140-mediated suppressive effects. In conclusion, our findings show that miR-140 acts as a tumor suppressor in OS by targeting HDAC4.

MicroRNA-494 inhibits proliferation and metastasis of osteosarcoma through repressing insulin receptor substrate-1

Despite microRNA-494 (miR-494) has a well-established role in many types of cancer; the biological function and potential mechanism of miR-494 in human osteosarcoma (OS) has not been elucidated. The aim of this study was therefore to investigate the role and underlying mechanism of miR-494 expression in osteosarcoma. Here, we found that miR-494 was significantly decreased in OS tissues and cell lines compared to the adjacent noncancerous bone tissues (P<0.01) and human normal osteoblast cells (NHOst) (P<0.05), respectively. Functional assays demonstrated that ectopic overexpression of miR-494 could significantly inhibit cell proliferation, colony formation, migration and invasion in vitro, as well as suppress tumor growth in nude mice model. Further integrative and functional studies suggested insulin receptor substrate 1 (IRS1) as a target gene of miR-494 in OS cells. IRS1 expression was upregulated, and inversely correlated with miR-494 expression in clinical OS tissues (r=-0.589, P=0.001). Moreover, downregulation of IRS1 had similar the inhibition effect on cell proliferation, colony formation, migration and invasion of miR-494 overexpression. Overexpresion of miR-494 obviously decreased AKT signal pathway activation. These findings suggested that miR-494 functioned as a tumor suppressor in OS, at least in part, by targeting IRS1.

Cell apoptosis, autophagy and necroptosis in osteosarcoma treatment

Osteosarcoma is the most common primary bone tumor in children and adolescents. Although combined therapy including surgery and multi-agent chemotherapy have resulted in great improvements in the overall survival of patients, chemoresistance remains an obstacle for the treatment of osteosarcoma. Molecular targets or effective agents that are actively involved in cell death including apoptosis, autophagy and necroptosis have been studied. We summarized how these agents (novel compounds, miRNAs, or proteins) regulate apoptotic, autophagic and necroptotic pathways; and discussed the current knowledge on the role of these new agents in chemotherapy resistance in osteosarcoma.

miR-338 inhibits the metastasis of lung cancer by targeting integrin β3

miR-338 as an intronic miRNA from apoptosis-associated tyrosine kinase (AATK) is involved in tumor proliferation and apoptosis, but its function and regulatory mechanism in lung cancer is still obscure. In the present study, we found that miR-338 was strikingly downregulated in 115 lung cancer tissues and 5 lung cancer cell lines. Besides, low level of miR-338 was associated with tumor emboli, TNM stage, tumor recurrence and poor survival. Regaining the expression of miR-338 in lung cancer cell lines significantly impaired cellular adhesion, migration, invasion and lung tumor formation in nude mice. Furthermore, we also identified a metastasis related protein, integrin β3 (ITGB3), as a novel target gene of miR-338. Our results reveal a new regulatory mechanism of miR-338 which may help us better understand the metastasis of lung cancer.

MicroRNA-138 functions as a tumor suppressor in osteosarcoma by targeting differentiated embryonic chondrocyte gene 2

BACKGROUND

MicroRNA-138 (miR-138) has been proven to be a tumor suppressor gene in various types of tumors. However, the expression and the role of miR-138 in human osteosarcoma are still poorly understood. We investigated the function and the underlying mechanism of miR-138 in osteosarcoma.

METHODS

The expression of miR-138 in human osteosarcoma tissues and cell lines was detected by real-time PCR analysis. The gain-of-function and loss-of-function experiments were performed on osteosarcoma cell lines to investigate the effects of miR-138 on osteosarcoma progression, and to determine whether differentiated embryonic chondrocyte gene 2 (DEC2) mediates these effects. Cell proliferation, apoptosis and invasion were assessed by MTT, flow cytometry and transwell-matrigel assays. Dual-luciferase reporter assay was used to identify whether DEC2 is a direct target of miR-138.

RESULTS

MiR-138 was significantly downregulated in human osteosarcoma tissues and cell lines. Moreover, miR-138 expression was significantly lower in metastatic osteosarcoma tissues than that in non-metastatic tissues. The in vitro gain-of-function and loss-of-function experiments demonstrated that miR-138 inhibited cell proliferation and invasion, and promoted cell apoptosis of human osteosarcoma cells. DEC2 was verified as a direct target of miR-138, and DEC2 could reverse the inhibitory effect of miR-138 on osteosarcoma progression.

CONCLUSIONS

These findings suggested that miR-138 acts as a tumor suppressor in osteosarcoma.miR-138 inhibited cell proliferation and invasion, as well as promoted cell apoptosis of human osteosarcoma cells, at least partially, by inhibiting the expression of DEC2. MiR-138/DEC2 may be a novel therapeutic target in osteosarcoma.

Genetic factors conferring metastasis in osteosarcoma

Osteosarcoma (OS) is a deadly bone malignancy affecting mostly children and adolescents. OS has outstandingly complex genetic alterations likely due to p53-independent genomic instability. Based on analysis of recent published research we claim existence of various genetic mechanisms of osteosarcomagenesis conferring great variability to different OS properties including metastatic potential. We also propose a model explaining how diverse genetic mechanisms occur and providing a framework for future research. P53-independent preexisting genomic instability, which precedes and frequently causes TP53 genetic alterations, is central in our model. In addition, our analyses reveal a possible cooperation between aberrantly activated HIF-1α and AP-1 genetic pathways in OS metastasis. We also review the involvement of noncoding RNA genes in OS metastasis.

Aberrant expression of microRNA-99a and its target gene mTOR associated with malignant progression and poor prognosis in patients with osteosarcoma

Background

The mammalian target of rapamycin (mTOR) has been reported to act as a target gene of microRNA (miR)-99a in various cancer cells and identified as an independent prognostic marker of human osteosarcoma. The aim of this study was to investigate the clinical significance of miR-99a/mTOR axis in human osteosarcoma.

Methods

A total of 130 pairs of osteosarcoma and matched noncancerous bone tissues were used to detect the expression levels of miR-99a and mTOR mRNA by quantitative real-time polymerase chain reaction. Then, associations of miR-99a and/or mTOR expression with clinico-pathological features and prognosis of patients with osteosarcoma were statistically analyzed.

Results

The expression levels of miR-99a (tumor vs normal: 2.11±1.03 vs 4.69±1.21, P<0.001) and mTOR mRNA (tumor vs normal: 4.40±1.13 vs 1.74±0.85, P<0.001) in osteosarcoma tissues were, respectively, lower and higher than those in noncancerous bone tissues. The expression levels of miR-99a in osteosarcoma tissues were negatively correlated with those of mTOR mRNA. Additionally, miR-99a-low and/or mTOR-high expression were all significantly associated with advanced surgical stage, positive metastasis and recurrence, and poor response to chemotherapy (all P<0.05). Moreover, patients with osteosarcoma with miR-99a-low and/or mTOR-high expression had shorter overall and disease-free survivals than those in miR-99a-high and/or mTOR-low expression groups. Multivariate Cox analyses showed that miR-99a and/or mTOR expression were all independent prognostic factors of osteosarcoma.

Conclusion

Our data showed the crucial role of miR-99a/mTOR axis in the malignant progression of human osteosarcoma, implying that conjoined expression of miR-99a and mTOR may offer an attractive novel prognostic marker for this disease.

Understanding the Osteosarcoma Pathobiology: A Comparative Oncology Approach

Osteosarcoma is an aggressive primary bone tumor in humans and is among the most common cancer afflicting dogs. Despite surgical advancements and intensification of chemo- and targeted therapies, the survival outcome for osteosarcoma patients is, as of yet, suboptimal. The presence of metastatic disease at diagnosis or its recurrence after initial therapy is a major factor for the poor outcomes. It is thought that most human and canine patients have at least microscopic metastatic lesions at diagnosis. Osteosarcoma in dogs occurs naturally with greater frequency and shares many biological and clinical similarities with osteosarcoma in humans. From a genetic perspective, osteosarcoma in both humans and dogs is characterized by complex karyotypes with highly variable structural and numerical chromosomal aberrations. Similar molecular abnormalities have been observed in human and canine osteosarcoma. For instance, loss of TP53 and RB regulated pathways are common. While there are several oncogenes that are commonly amplified in both humans and dogs, such as MYC and RAS, no commonly activated proto-oncogene has been identified that could form the basis for targeted therapies. It remains possible that recurrent aberrant gene expression changes due to gene amplification or epigenetic alterations could be uncovered and these could be used for developing new, targeted therapies. However, the remarkably high genomic complexity of osteosarcoma has precluded their definitive identification. Several advantageous murine models of osteosarcoma have been generated. These include spontaneous and genetically engineered mouse models, including a model based on forward genetics and transposon mutagenesis allowing new genes and genetic pathways to be implicated in osteosarcoma development. The proposition of this review is that careful comparative genomic studies between human, canine and mouse models of osteosarcoma may help identify commonly affected and targetable pathways for alternative therapies for osteosarcoma patients. Translational research may be found through a path that begins in mouse models, and then moves through canine patients, and then human patients.

miR-22 inhibits the proliferation, motility, and invasion of human glioblastoma cells by directly targeting SIRT1

Recently, microRNAs (miRNAs), a kind of small and non-coding RNA, can target the downstream molecules. Increasing evidence demonstrates that miRNAs meditate the onset and progression of a variety of tumors. In the present study, we carried out gene transfection, western blot, and reverse transcription PCR (RT-PCR) to explore the role of miR-22 in glioblastoma tissues and cell lines. Here, we verified that the expression of miR-22 was downregulated in glioblastoma tissues and cells rather than matched non-tumor tissues and normal human astrocyte (NHA) cells (p < 0.001). By contrast, SIRT1 messenger RNA (mRNA) and protein were upregulated in glioblastoma tissues and cells (p < 0.001). In vitro miR-22 mimics interfered with cell proliferation, migration, and invasion of U87 and U251 cells. Mechanically, the 3'-untranslated regions (3'-UTRs) of SIRT1 were a direct target of miR-22, leading to the decreased expression of SIRT1 protein in U87 and U251 cells. Meanwhile, miR-22 mimics also inhibited the expression of epidermal growth factor receptor (EGFR) and matrix metallopeptidase 9 (MMP9). In conclusion, miR-22 inhibited cell proliferation, migration, and invasion via targeting the 3'-UTR of SIRT1 in the progression of glioblastoma and miR-22-SIRT1 pathway can be recommended as a potential target for treatment of glioblastoma.

Upregulated miRNA-622 inhibited cell proliferation, motility, and invasion via repressing Kirsten rat sarcoma in glioblastoma

Glioblastoma has been reported as one of the leading causes of cancer-related death, and some factors including oncogenic genes and environments are involved in tumorigenesis. MicroRNAs (miRNAs) act as a kind of small and noncoding RNA, which can target the downstream molecules. Emerging reports demonstrate that microRNAs regulate the initiation and progression of different cancers. In the present study, we conducted in vitro experiment as well as clinical studies in a cohort of 20 glioblastoma samples. We demonstrated that miR-622 expression was lower in tumor tissues and cells, when compared to normal brain tissues and normal human astrocyte (NHA) cells, while K-Ras messenger RNA (mRNA) and protein showed the opposite expression profile. Overexpression of miR-622 suppressed tumor cell proliferation, migration, and invasion of A172, U87, and U251 cells. Accordingly, the proliferating cell nuclear antigen (PCNA), matrix metallopeptidase 2 (MMP2), and MMP9 expressions were also decreased due to miR-622 overexpression. Importantly, we discovered that wild Kirsten rat sarcoma (K-Ras) was a direct target of miR-622, which decreased the expression of K-Ras protein in A172, U87, and U251 cells. In conclusion, upregulated miRNA-622 inhibited cell proliferation, migration, and invasion via repressing K-Ras in the progression of glioblastoma, and miR-622-K-Ras pathway can be recommended as a potential target for treatment of glioblastoma.

The overexpression of miR-30a affects cell proliferation of chondrosarcoma via targeting Runx2

MicroRNAs (miRNAs) are emerging as important epigenetic modulators of multiple target genes, leading to abnormal cellular signaling involving cellular proliferation in cancers. Aberrant miRNA expression has been observed in human chondrosarcoma (CS). The purpose of the present study was to evaluate the expression and molecular mechanisms of Runx2 and miR-30a in human CS tissues and CS cell lines JJ012, SW1353, and L3252. In the present study, we found that the expression of miR-30a was markedly downregulated in CS cell lines and human CS tissues, compared to matched non-tumor-associated tissues. Furthermore, miR-30a expression was inversely proportional to that of Runx2 messenger RNA (mRNA) and protein. Upregulation of miR-30a dramatically reduced the proliferation, colony formation, and cell cycle-related proteins of CS cells. Flow cytometry analysis showed that ectopic expression of miR-30a significantly decreased the percentage of S phase cells and increased the percentage of G1/G0 phase cells. Luciferase reporter assays confirmed that miR-30a binding to the 3'-untranslated region (3'-UTR) region of Runx2 inhibited the expression of Runx2 in cancer cells. Taken together, our results suggest that miR-30a plays an important role to inhibit the proliferation of CS cells and presents a novel mechanism for direct miRNA-mediated suppression of Runx2 in CS. Thus, miR-30a/Runx2 may have an important role in treatment of CS patients.

The upregulation of miRNA-146a inhibited biological behaviors of ESCC through inhibition of IRS2

In recent years, microRNAs, also called as miRNAs, play an important role in carcinogenesis, and the dysregulation of miRNAs is closely associated with cancer progression. Till now, little has been known about the role of miRNA-146a in the esophageal squamous cell carcinomas (ESCC). In the present study, we used in vitro assays to investigate the mechanisms of miRNA-146a in ESCC cell lines and 60 ESCC tissues. Here, we found that miRNA-146a expression is downregulated in both ESCC cell lines and tissues and obviously associated with pathological indicators, such as metastasis and stage of ESCC. In addition, the overexpression of miRNA-146a suppressed EC109 and TE8 cell proliferation and invasion. Meanwhile, miRNA-146a overexpression extremely inhibited the protein expression of insulin receptor substrate 2 (IRS2). Notably, the enforced expression of IRS2 in EC109 cells with miRNA-146a overexpression attenuated the inhibitory effects of miRNA-146a. In conclusion, our findings suggest that miRNA-146a may function as a useful clinical tool in the treatment and diagnosis of ESCC, and its overexpression suppressed cell growth through inhibition of IRS2. Thus, miRNA-146a pathway may be recommended as potential makers for drug design.