MiR-221 increases osteosarcoma cell proliferation, invasion and migration partly through the downregulation of PTEN

New emerging targets in osteosarcoma therapy: PTEN and PI3K/Akt crosstalk in carcinogenesis

Osteosarcoma (OS) is a malignant bone carcinoma that affects people in childhood and adulthood. The heterogeneous nature and chromosomal instability represent certain characteristics of OS cells. These cancer cells grow and migrate abnormally, making the prognosis undesirable for patients. Conventional and current treatments fail to completely eradicate tumor cells, so new therapeutics targeting genes may be considered. PI3K/Akt is a regulator of events such as growth, cell death, migration, and differentiation, and its expression changes during cancer progression. PTEN reduces PI3K/Akt expression, and its mutations and depletions have been reported in various tumors. Experimental evidence shows that there is upregulation of PI3K/Akt and downregulation of PTEN in OS. Increasing PTEN expression may suppress PI3K/Akt to minimize tumorigenesis. In addition, PI3K/Akt shows a positive association with growth, metastasis, EMT and metabolism of OS cells and inhibits apoptosis. Importantly, overexpression of PI3K/Akt causes drug resistance and radio-resistance and its level can be modulated by miRNAs, lncRNAs and circRNAs. Silencing PI3K/Akt by compounds and drugs can suppress OS. Here, we review in detail the function of the PTEN/PI3K/Akt in OS, revealing its biological function, function in tumor progression, resistance to therapy, and pharmacological significance.

Signal Pathways and microRNAs in Osteosarcoma Growth and the Dual Role of Mesenchymal Stem Cells in Oncogenesis

The major challenges in Osteosarcoma (OS) therapy are its heterogeneity and drug resistance. The development of new therapeutic approaches to overcome the major growth mechanisms of OS is urgently needed. The search for specific molecular targets and promising innovative approaches in OS therapy, including drug delivery methods, is an urgent problem. Modern regenerative medicine focuses on harnessing the potential of mesenchymal stem cells (MSCs) because they have low immunogenicity. MSCs are important cells that have received considerable attention in cancer research. Currently, new cell-based methods for using MSCs in medicine are being actively investigated and tested, especially as carriers for chemotherapeutics, nanoparticles, and photosensitizers. However, despite the inexhaustible regenerative potential and known anticancer properties of MSCs, they may trigger the development and progression of bone tumors. A better understanding of the complex cellular and molecular mechanisms of OS pathogenesis is essential to identify novel molecular effectors involved in oncogenesis. The current review focuses on signaling pathways and miRNAs involved in the development of OS and describes the role of MSCs in oncogenesis and their potential for antitumor cell-based therapy.

MicroRNAs and osteosarcoma: Potential targets for inhibiting metastasis and increasing chemosensitivity

Osteosarcoma (OS) is the third most common cancer in young adults after lymphoma and brain cancer. Metastasis, like other cellular events, is dependent on signaling pathways; a series of changes in some proteins and signaling pathways pave the way for OS cells to invade and migrate. Ezrin, TGF-β, Notch, RUNX2, matrix metalloproteinases (MMPs), Wnt/β-catenin, and phosphoinositide 3-kinase (PI3K)/AKT are among the most important of these proteins and signaling pathways. Despite the improvements in treating OS, the overall survival of patients suffering from the metastatic disease has not experienced any significant change after surgical treatments and chemotherapy and 5-years overall survival in patients with metastatic OS is about 20%. Studies have shown that overexpression or inhibition of some microRNAs (miRNAs) has significant effects in limiting the invasion and migration of OS cells. The results of these studies highlight the potential of the clinical application of some miRNA mimics and miRNA inhibitors (antagomiRs) to inhibit OS metastasis in the future. In addition, some studies have shown that miRNAs are associated with the most important drug resistance mechanisms in OS, and some miRNAs are highly effective targets to increase chemosensitivity. The results of these studies suggest that miRNA mimics and antagomiRs may be helpful to increase the efficacy of conventional chemotherapy drugs in the treatment of metastatic OS. In this article, we discussed the role of various signaling pathways and the involved miRNAs in the metastasis of OS, attempting to provide a comprehensive review of the literature on OS metastasis and chemosensitivity.

miR-221/222 as biomarkers and targets for therapeutic intervention on cancer and other diseases: A systematic review

Among deregulated microRNAs (miRs) in human malignancies, miR-221 has been widely investigated for its oncogenic role and as a promising biomarker. Moreover, recent evidence suggests miR-221 as a fine-tuner of chronic liver injury and inflammation-related events. Available information also supports the potential of miR-221 silencing as promising therapeutic intervention. In this systematic review, we selected papers from the principal databases (PubMed, MedLine, Medscape, ASCO, ESMO) between January 2012 and December 2020, using the keywords “miR-221” and the specific keywords related to the most important hematologic and solid malignancies, and some non-malignant diseases, to define and characterize deregulated miR-221 as a valuable therapeutic target in the modern vision of molecular medicine. We found a major role of miR-221 in this view.

Research Progress of Exosome-Loaded miRNA in Osteosarcoma

Currently, although the improvement of surgical techniques and the development of chemotherapy drugs have brought a certain degree of development to the treatment of osteosarcoma, the treatment of osteosarcoma has many shortcomings, and its treatment is limited. MiRNAs and exosomes can be used as diagnostic tools, and they play an important role in the occurrence and chemotherapy resistance of osteosarcoma. Therefore, providing a new method for the treatment of osteosarcoma is the key to solving this problem. To systematically summarize the research status of exoskeleton drug-loaded miRNA in osteosarcoma, we identified and evaluated 208 studies and found that exosome-carrying miRNA can be used as an index for the diagnosis and prognosis of osteosarcoma and share a certain relationship with chemosensitivity. In addition, exosomes can also be used as a carrier of genetic drugs able to regulate the progression of osteosarcoma. Based on the above findings, we propose suggestions for the future development of this field, aiming to bring new ideas for the early diagnosis and treatment of osteosarcoma.

miR221 regulates cell migration by targeting annexin a1 expression in human mesothelial MeT-5A cells neoplastic-like transformed by multi-walled carbon nanotube

Background

Multi-walled carbon nanotube (MWCNT) is one of the most widely used manufactured nanomaterials, however, its potential harmful effect on human health is of great concern. Previously we have shown the acute and chronic exposure to MWCNT induced different responses in human mesothelial MeT-5A cells. In the current study, MeT-5A cells were continuously subjected to MWCNT exposure at 10 μg/cm² for 48 h per passage, up to a whole year, to further clarify the carcinogesis and its potential mechanisms of MWCNT.

Results

After one-year MWCNT treatment, MeT-5A cells exhibited neoplastic-like properties, including morphological changes, anchorage-independent growth, increased cell proliferation and cell migration. Further examination revealed the expression of microRNA 221 (miR221) was gradually decreased, while the annexin a1 expression was increased at both the mRNA and protein level during the exposure. Bioinformatic analysis indicated that annexin a1 is a target for miR221 regulation, and it was confirmed by transfecting cells with miR221 mimics, which resulted in the downregulation of annexin a1. Detailed analyses demonstrated miR221 was involved in the regulation of cell migration, e.g., downregulation of miR221 or overexpression of ANNEXIN A1, contributed to the increased cell migration. In contrast, overexpression of miR221 or downregulation of ANNEXIN A1 slowed cell migration.

Conclusions

Taken together, these results point to a neoplastic-transforming property of MWCNT, and the miR221-annexin a1 axis is involved in the regulation of cell migration in the transformed cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41021-021-00209-y.

MicroRNAs: The Link between the Metabolic Syndrome and Oncogenesis

Metabolic syndrome (MetS) represents a cluster of disorders that increase the risk of a plethora of conditions, in particular type two diabetes, cardiovascular diseases, and certain types of cancers. MetS is a complex entity characterized by a chronic inflammatory state that implies dysregulations of adipokins and proinflammatory cytokins together with hormonal and growth factors imbalances. Of great interest is the implication of microRNA (miRNA, miR), non-coding RNA, in cancer genesis, progression, and metastasis. The adipose tissue serves as an important source of miRs, which represent a novel class of adipokines, that play a crucial role in carcinogenesis. Altered miRs secretion in the adipose tissue, in the context of MetS, might explain their implication in the oncogenesis. The interplay between miRs expressed in adipose tissue, their dysregulation and cancer pathogenesis are still intriguing, taking into consideration the fact that miRNAs show both carcinogenic and tumor suppressor effects. The aim of our review was to discuss the latest publications concerning the implication of miRs dysregulation in MetS and their significance in tumoral signaling pathways. Furthermore, we emphasized the role of miRNAs as potential target therapies and their implication in cancer progression and metastasis.

miR-221-3p promotes hepatocellular carcinogenesis by downregulating O6-methylguanine-DNA methyltransferase

This study aimed to investigate the influence of miR-221-3p and O⁶-methylguanine-DNA methyltransferase (MGMT) interaction in human hepatocellular carcinoma (HCC), thereby revealing a novel molecular mechanism of hepatic carcinogenesis involving miR-221-3p and MGMT.

Fluorescence qPCR and immunoblot assays were performed to determine the expression of RNA and protein in HCC tissues and cell lines. We also employed the firefly and Renilla luciferase assay to verify the target relationship between miR-221-3p and MGMT mRNA. Assessments including the MTT assay, wound-healing assay, transwell assay, colony foci formation experiment, and flow cytometric experiment were carried out to determine the viability, migration, invasion, proliferation, cell cycle progression, and apoptosis of SMMC-7721 and BEL-7404 cell lines with the modulated expression of miR-221-3p and MGMT. Compared to healthy tissues and cell line HL7702, miR-221-3p was significantly upregulated but MGMT was significantly downregulated in carcinomas and cancerous cell lines. Forced miR-221-3p overexpression was found to enhance the proliferation, migration, invasion, and clonogenicity of cell lines, but it suppressed cell apoptosis. Findings also revealed that forced miR-221-3p overexpression had little effect on cell cycle progression. After MGMT was confirmed to be atarget gene of miR-221-3p, it was found that the forced upregulation of miR-221-3p downregulated MGMT mRNA and protein levels significantly. MiR-221-3p was identified as an HCC promoting factor, and it specifically inhibited the expression of the MGMT. Besides, the upregulation of miR-221-3p had apositive influence on HCC pathogenesis by inhibiting MGMT expression.

PTEN in osteosarcoma: Recent advances and the therapeutic potential

Osteosarcoma is the most common primary malignant bone tumor, predominantly occurring in children and adolescents. Despite treated with surgery and neoadjuvant chemotherapy, osteosarcoma has a high potential of local recurrence and lung metastasis. Overall survival rates for osteosarcoma have plateaued in the past four decades, therefore, identification of novel targets and development of more effective treatment strategies are urgent. Phosphatase and tensin homolog (PTEN) is a tumor suppressor gene that negatively regulates the phosphatidylinositol 3-kinase (PI3K)/ protein kinase B (AKT)/ mammalian target of rapamycin (mTOR) pathway. Over half of clinical osteosarcoma samples presented loss or low expression of PTEN, which usually indicated an advanced stage of tumor and a poor prognosis. The expression of PTEN is regulated by epigenetic silence, transcription regulation, post-translational modifications, and protein interactions in osteosarcoma. Therefore, explicating regulations to restore the anti-tumor function of PTEN might provide novel targeted therapies for osteosarcoma. Preclinical evidence suggested directly targeting the altered PTEN in osteosarcoma was promising. Current clinical application of PTEN related therapies in osteosarcoma are PI3K/mTOR inhibitors, and these drugs have shown the favorable efficacy in patients with advanced osteosarcoma.

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.

Exosomes derived from normal human bronchial epithelial cells down-regulate proliferation and migration of hydroquinone-transformed malignant recipient cells via up-regulating PTEN expression

The gene encoding the tumor suppressor, phosphatase and tensin homolog (PTEN), located on chromosome 10, is frequently expressed at low levels in various tumors, resulting in the stimulation of cell proliferation and migration. However, the role of exosomal PTEN in cell-cell communication during the progress of benzene-induced carcinogenesis remains unclear. The goal of this study was to explore whether exosomes derived from normal human bronchial epithelial cells (16HBE) could transmit PTEN to hydroquinone-transformed malignant recipient cells (16HBE-t) and its possible effects on cell proliferation and migration. Consistent with PTEN expression being down-regulated in transformed cells, we found that its expression was significantly decreased in 16HBE-t relative to 16HBE cells and that purified exosomes secreted by 16HBE, up-regulated PTEN levels in recipient 16HBE-t cells. Thus, down-regulating their proliferation and migration. Further, when exosomes derived from 16HBE cells that had been treated with the PTEN inhibitor SF1670, were incubated with recipient 16HBE-t cells, they exhibited decreased PTEN levels, with a corresponding increase in their proliferation and migration. In conclusion, our study demonstrates that exosomes derived from 16HBE cells can down-regulate proliferation and migration of recipient 16HBE-t cells via transferring PTEN.

MicroRNA-221 and MicroRNA-222 in Common Human Cancers: Expression, Function, and Triggering of Tumor Progression as a Key Modulator

MicroRNAs (miRNAs) are a class of short (~22 nucleotides [nt]), single-stranded RNA oligonucleotides that are regulatory in nature and are often dysregulated in various diseases, including cancer. miRNAs can act as oncomiRs (miRNAs associated with cancer) or tumor suppressor miRNAs and have the potential to be a diagnostic, prognostic, noninvasive biomarker for these diseases. MicroRNA-221 (miR-221) and microRNA-222 (miR-222) are homologous miRNAs, located on the human chromosome Xp11.3, which factored significantly in impairment in the regulation of a wide range of cancers. In this review, we have highlighted the most consistently reported dysregulated miRNAs that trigger human tissues to express cancerous features and surveyed the role of those miRNAs in metastasis, apoptosis, angiogenesis, and tumor prognosis. Also, we applied the causes of drug resistance and the role of coordinated actions of these miRNAs to epigenetic changes and selected miRNAs as a potential type of cancer treatment.

miRNA signatures in childhood sarcomas and their clinical implications

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

Downregulation of miR-136 promotes the progression of osteosarcoma and is associated with the prognosis of patients with osteosarcoma

Osteosarcoma (OS) is the most common bone tumor in children and young adults, and is an aggressive tumor with poor prognosis. MicroRNAs (miRNAs) are aberrantly expressed in various types of cancer, and contribute to cancer tumorigenesis and progression. In the present study, the potential prognostic value and biological function of miRNA-136 (miR-136) in OS was investigated. Reverse transcription-quantitative polymerase chain reaction analysis was used to evaluate the expression of miR-136 in OS tissues and cell lines. Kaplan-Meier survival analysis and Cox regression analysis were conducted to investigate the prognostic significance of miR-136. Various in vitro cell based assays were used to evaluate the effects of miR-136 on the biological behavior of OS cells. A luciferase assay was performed to determine the key miR-136 targets associated with OS. The expression of miR-136 was significantly downregulated in osteosarcoma tissues and cells compared with the normal controls (all P<0.05). Decreased miR-136 expression was significantly associated with Enneking staging (P=0.030) and distant metastasis (P=0.016). Decreased miR-136 expression in patients was associated with shorter overall survival compared with patients with increased expression levels (log-rank test; P<0.05). The expression of miR-136 was indicated as an independent prognostic factor for the patients (hazard ratio=0.496; 95% confidence interval=0.250-0.987; P=0.046). MTT, transwell and Matrigel assays demonstrated that upregulation of miR-136 decreased proliferation, migration and invasion of OS cells. Bioinformatics and luciferase assays demonstrated that migration and invasion enhancer 1 (MIEN1) is a direct target of miR-136. Together, the results suggested that miR-136 functions as a tumor suppressor gene to regulate proliferation, migration and invasion of OS cells. MIEN1 was a potential target of miR-136. Additionally, miR-136 may serve as a prognostic biomarker for OS.

Novel Germline PTEN Mutation Associated with Cowden Syndrome and Osteosarcoma

BACKGROUND

Cowden syndrome (CS) is a rare autosomal-dominant inherited disorder characterized by multiple hamartomas. While the hamartomas are benign, patients with CS have increased risk of osteosarcoma and of breast, thyroid, endometrial, soft-tissue and colonic neoplasms. Germline mutations of phosphatase and tensin homolog (PTEN) are implicated in CS and in the development of osteosarcoma. We report a patient with CS who presented with osteosarcoma, ganglioneuromatosis and a benign breast mass. Osteosarcoma, as presentation of CS, is rare (only one report in the English literature). Genomic DNA from the patient's peripheral blood was quantified by spectrophotometry, then underwent sequence enrichment, polymerase chain reaction and next-generation sequencing. Molecular analysis revealed a non-synonymous c.17_18delAA frameshift mutation in exon 1 of PTEN and a c.116G>T (p.R39L) missense mutation of serine/threonine kinase 11 (STK11) of unknown significance.

CONCLUSION

We report a patient with CS presenting with ganglioneuromatosis, benign breast mass and osteosarcoma, harboring a novel molecular alteration in PTEN which to our knowledge has not been previously reported.

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

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

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

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

Comparison of the miRNA expression profiles in fresh frozen and formalin-fixed paraffin-embedded tonsillar tumors

MicroRNAs are considered as promising prognostic and diagnostic biomarkers of human cancer since their profiles differ between tumor types. Most of the tumor profiling studies were performed on rarely available fresh frozen (FF) samples. Alternatively, archived formalin-fixed paraffin-embedded (FFPE) tissue samples are also well applicable to larger-scale retrospective miRNA profiling studies. The aim of this study was to perform systematic comparison of the miRNA expression profiles between FF and macrodissected FFPE tonsillar tumors using the TaqMan Low Density Array system, with the data processed by different software programs and two types of normalization methods. We observed a marked correlation between the miRNA expression profiles of paired FF and FFPE samples; however, only 27-38% of the differentially deregulated miRNAs overlapped between the two source systems. The comparison of the results with regard to the distinct modes of data normalization revealed an overlap in 58-67% of differentially expressed miRNAs, with no influence of the choice of software platform. Our study highlights the fact that for an accurate comparison of the miRNA expression profiles from published studies, it is important to use the same type of clinical material and to test and select the best-performing normalization method for data analysis.

Long Noncoding RNA GAS5 Suppresses Cell Growth and Epithelial-Mesenchymal Transition in Osteosarcoma by Regulating the miR-221/ARHI Pathway

Dysregulated long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) play key roles in the development of human cancers. The lncRNA growth arrest-specific 5 (GAS5) is reported to be a tumor suppressor in multiple cancers. However, the roles of GAS5 and its related miRNAs in osteosarcoma are poorly understood. This study explored the potential functions and mechanisms of GAS5 in the tumorigenesis of osteosarcoma. Here, the expression of GAS5, miR-221 and aplasia Ras homologue member I (ARHI) was determined in osteosarcoma tissues and cells by Real-time PCR (RT-qPCR). The underlying mechanism of GAS5 in osteosarcoma growth was analyzed via MTT, Transwell, RT-qPCR, Western blot, dual-luciferase reporter assay, RNA immunoprecipitation, and xenograft models after GAS5 overexpression. GAS5 and ARHI levels were significantly reduced, while miR-221 increased, both in osteosarcoma tissues and cells. Overexpression of GAS5 suppressed the proliferation, migration, and epithelial-mesenchymal transition (EMT) of osteosarcoma cells. GAS5 could directly bind to miR-221 to decrease miR-221 expression and enhance ARHI expression. The effect of GAS5 overexpression on the proliferation, migration and EMT was reversed by miR-221 mimics or ARHI siRNA in osteosarcoma cells. Additionally, GAS5 suppressed tumor volume, Ki-67 and PCNA staining, and EMT process in the development of osteosarcoma in vivo. Taken together, lncRNA GAS5 functions as a competing endogenous RNA for miR-221 to suppress cell growth and EMT in osteosarcoma by regulating the miR-221/ARHI pathway. J. Cell. Biochem. 118: 4772-4781, 2017. © 2017 Wiley Periodicals, Inc.

MiR-19a regulates the cell growth and apoptosis of osteosarcoma stem cells by targeting PTEN

MicroRNAs are small, endogenous, and non-coding RNAs that play important regulatory roles in multiple biological processes in cancers. Recent evidence has indicated that miR-19a participates in the cancer tumorigenic progression. However, the functional roles of miR-19a in cancer stem cells are still unclear. As the cancer stem cells are considered to be responsible for the tumor recurrence and treatment failure in osteosarcoma, the aim of this study is to investigate the molecular mechanism of miR-19a underlying osteosarcoma tumorigenesis. In this study, we observed significant upregulation of miR-19a in osteosarcoma patients' tumor tissues as well as the osteosarcoma cell lines in vitro. We showed that knockdown of miR-19a by its antisense oligonucleotide (anti-miR-19a) significantly decreased the population of cancer stem cells in osteosarcoma cell lines. Furthermore, we found the miR-19a regulated the cell proliferation, migration, and viability in the human osteosarcoma-cancer stem cells. The gene of phosphatase and tensin homolog deleted on chromosome 10, which is an important tumor suppressor, was found to be directly regulated by miR-19a in human osteosarcoma-cancer stem cells. We demonstrated that knockdown of miR-19a increased the expression of phosphatase and tensin homolog deleted on chromosome 10. As the anti-miR-19a inhibited the phosphatidylinositol 3-kinase/AKT pathway and induced apoptosis of human osteosarcoma-cancer stem cells, the phosphatase and tensin homolog deleted on chromosome 10 small interfering RNA inhibited the effect of it. Meanwhile, the phosphatase and tensin homolog deleted on chromosome 10 small interfering RNA also abolished the effect of anti-miR-19a on inhibiting the cell proliferation, migration, and viability in the human osteosarcoma-cancer stem cells. In conclusion, our findings demonstrated that dysregulation of miR-19a plays critical roles in the osteosarcoma stem cells, at least in part via targeting the phosphatase and tensin homolog deleted on chromosome 10. Knockdown of miR-19a may represent a potential strategy for the osteosarcoma treatment.

MicroRNA-409-3p inhibits osteosarcoma cell migration and invasion by targeting catenin-δ1

Osteosarcoma is the most common primary bone cancer which is associated with early metastatic potential and poor prognosis. However, the molecular mechanisms underlying osteosarcoma progression are not well characterized. Here, we investigated the role of miR-409-3p in osteosarcoma metastasis. Osteosarcoma tissue showed decreased expression of miR-409-3p compared to adjacent non-tumorous tissue. The expression level of miR-409-3p was negatively correlated with osteosarcoma metastasis. Overexpression of miR-409-3p in osteosarcoma cells (U2OS) inhibited cell migration and invasion. Bioinformatics analysis showed that catenin-δ1 (CTNND1, p120-catenin) is a direct target of miR-409-3p. Overexpression of miR-409-3p repressed the expression of catenin-δ1 in U2OS cells at both mRNA and protein levels. Meanwhile, miR-409-3p repressed the activity of luciferase reporter containing the 3'-untranslated region (3'UTR) of CTNND1 gene. Furthermore, expression of catenin-δ1 rescued the inhibitory effect of miR-409-3p on cell migration and invasion. Altogether, these results indicated that miR-409-3p targets catenin-δ1 to repress osteosarcoma metastasis.