Role of miR-142 in the pathogenesis of osteosarcoma and its potential as therapeutic approach

Identification of novel diagnostic and prognostic microRNAs in sarcoma on TCGA dataset: bioinformatics and machine learning approach

The discovery of unique microRNA (miR) patterns and their corresponding genes in sarcoma patients indicates their involvement in cancer development and suggests their potential use in medical management. MiRs were identified from The Cancer Genome Atlas (TCGA) dataset, with a Deep Neural Network (DNN) employed for novel miR identification. MiRDB facilitated target predictions. Functional enrichment analysis, identify critical pathways, protein-protein interaction network, and diseases/clinical data correlations were explored. COX regression, Kaplan-Meier analyses, and CombioROC was also utilized. The population consisted of 119 females and 142 males, and 1046 miRs were uncovered. Ten miRs was selected for further analysis using DNN. Upon analyzing for gene ontology, it was found that these genes showed enrichment in various activities. We identified a significant association between the overall survival rate of sarcoma patients and miRs levels. The combination of miR.3688 and miR.3936 achieved the greatest diagnostic standing. MiRs have the capability to screen sarcoma patients to identify undetected tumors, predict prognosis, and pinpoint prospective targets for treatment. Further large clinical trials are required to validate our findings.

Hsa_circ_0001480 affects osteosarcoma progression by regulating the miR-363-3p/IBSP pathway

Osteosarcoma (OS) is a malignant bone tumor that commonly affects young individuals. Circular RNAs (circRNAs) are associated with OS progression. In this study, we aimed to determine the role of hsa_circ_0001480 (circ_0001480) in OS development. OS cell invasion, viability, and colony numbers were assessed via transwell, cell counting kit-8, and colony formation assays, respectively. Tumor growth in vivo was also assessed using an OS mouse model. Additionally, targeted associations among the integrin-binding sialoprotein (IBSP), microRNA (miR)-363-3p, and circ_0001480 were evaluated via RNA immunoprecipitation and dual luciferase reporter assays, whereas their expression levels in OS cells and tissues were determined via quantitative reverse transcription-polymerase chain reaction and western blotting. Loss of circ_0001480 or IBSP significantly inhibited the proliferation and invasion of OS cells, but this effect was reversed by miR-363-3p downregulation. Moreover, circ_0001480 knockdown inhibited neoplasm growth in vivo. circ_0001480 directly bound to miR-363-3p, which further modulated IBSP. Both circ_0001480 and IBSP levels were high, whereas miR-363-3p levels were low in OS cells. Furthermore, low miR-363-3p levels attenuated the suppressive effects of circ_0001480 silencing on the proliferation and invasion of OS cells; however, loss of IBSP partially reversed these effects. Overall, our findings revealed circ_0001480 an oncogenic circRNA stimulating OS progression by modulating the miR-363-3p/IBSP pathway, suggesting its potential for OS treatment.

The evaluation of PD-1 and Tim-3 expression besides their related miRNAs in PBMCs of women with recurrent pregnancy loss

Recurrent pregnancy loss (RPL) is a multifactorial disorder, associated with immunologic abnormalities. During pregnancy, the maternal immune system uses different tolerance mechanisms to deal with a semi-allogenic fetus. The expression of immune checkpoints and their related miRNAs in immune cells can ensure pregnancy at the feto-maternal interface by modulating immune responses. This study aims to evaluate the expression of the immune checkpoint molecules PD-1 and Tim-3 on circulating T cells by flow cytometry, that of mir-138 and mir-155 in PBMCs by Real-time PCR, and the concentrations of TGF-β and IP-10 in the sera of women suffering from RPL as well as of gestational age-matched healthy pregnant women by ELISA. The percentage of PD-1 or Tim-3 expressing CD8+ T cells was significantly lower in RPL patients compared to the controls, while there was no significant difference in Tim-3 expression of CD4+ T cells between the two groups. The mRNA of both the PD-1 and Tim-3 genes were downregulated in PBMCs of RPL patients compared to controls, however, the difference was not statistically significant for Tim-3. The concentration of TGF-β was significantly lower and that of IP-10 was significantly higher in the sera of RPL patients than in those of the controls. The relative expression of mir-138 and miR-155 were significantly lower, in PBMCs of RPL patients than in those of healthy pregnant women. These data confirm that by affecting cytokine production, immune checkpoints, and microRNAs play a role in establishing the appropriate local immune environment for successful pregnancy. The wider analysis of immune checkpoints may also yield new biomarkers for the diagnosis and prevention of RPL.

Soy isoflavones induces mitophagy to inhibit the progression of osteosarcoma by blocking the AKT/mTOR signaling pathway

BACKGROUND

Soy isoflavones (SI) is a natural bioactive substance exhibiting beneficial effects on human health. This study aims to elucidate the therapeutic potential of SI in the treatment of osteosarcoma (OS) and to investigate the underlying mechanisms, particularly focusing on mitophagy.

METHODS

The effects of SI on the proliferation, apoptosis, migration, and invasion of U2OS cells were analyzed. Mitophagy was assessed through multiple parameters: mitochondrial autophagosomes, mitochondrial membrane potential, autophagy-related proteins, reactive oxygen species (ROS), and oxygen consumption rate (OCR). Protein levels related to apoptosis, autophagy, and the AKT/mTOR pathway were analyzed using western blot. The therapeutic efficacy of SI was further identified using a mouse tumor xenograft model. Cell apoptosis and proliferation in tumor xenografts were detected by TUNEL staining and immunohistochemistry (IHC), respectively.

RESULTS

SI dose-dependently suppressed the viability, colony formation, migration, and invasion of U2OS cells, and enhanced the apoptosis. SI also dose-dependently induced mitophagy in OS cells, evidenced by an increase in autophagosomes and ROS levels, a decrease in mitochondrial membrane potential and OCR, and concomitant changes in autophagy-related proteins. Mdivi-1, an inhibitor of mitophagy, reversed the anti-tumor effects of SI on U2OS cells. In addition, SI blocked the AKT/mTOR pathway in U2OS cells. SC-79, an AKT agonist, reversed the effect of SI on inducing mitophagy. Moreover, SI also promoted cell apoptosis and mitophagy in tumor xenografts in vivo.

CONCLUSIONS

SI induces mitophagy in OS cells by blocking the AKT/mTOR pathway, contributing to the inhibition of OS.

Expression of E-cadherin and N-cadherin in Epithelial-to-Mesenchymal Transition of Osteosarcoma: A Systematic Review

Osteosarcoma (OS) is a debilitating cancer of the bone that commonly afflicts the young and old. This may be de novo or associated with tumorigenic syndromes. However, many molecular mechanisms are still being uncovered and may offer greater avenues for screening and therapy. Cadherins, including E-cadherin and N-cadherin/vimentin, are involved in epithelial-to-mesenchymal transmission (EMT), which is key for tumor invasion. A study reviewing the relationship between OS and cadherins might elucidate a potential target for therapy and screening. A robust literature review was conducted by searching PubMed with the keywords "osteosarcoma", "cadherin", "e-cadherin" and "n-cadherin". Of a preliminary 266 papers, 25 were included in the final review. Review articles and those without primary data were excluded. Loss of E-cadherin is noted in metastatic cell lines of osteosarcoma. Overexpression of E-cadherin or knockout of N-cadherin/vimentin results in loss of metastatic potential. There are several methods of gene knockout, including CRISPR-Cas9 gene editing, viral vector insertion with micro RNA complementary to long noncoding RNA within gene segments, or proteomic editing. Screening for EMT and genetic treatment of EMT is a possible avenue for the treatment of refractory osteosarcoma. Several studies were conducted ex vivo. Further testing involving in vitro therapy is necessary to validate these methods. Limitations of this study involve a lack of in vivo trials to validate methods.

Correlation of TIMP1-MMP2/MMP9 Gene Expression Axis Changes with Treatment Efficacy and Survival of NSCLC Patients

In the course of lung cancer, normal cells are transformed into cancerous ones, and changes occur in the microenvironment, including the extracellular matrix (ECM), which is not only a scaffold for cells, but also a reservoir of cytokines, chemokines and growth factors. Metalloproteinases (MMPs) are among the elements that enable ECM remodeling. The publication focuses on the problem of changes in the gene expression of MMP2, MMP9 and tissue inhibitor of metalloproteinases (TIMP1) in the blood of NSCLC patients during therapy (one year after surgical resection of the tumor). The paper also analyzes differences in the expression of the studied genes in the tumor tissue, as well as data collected in publicly available databases. The results of blood tests showed no differences in the expression of the tested genes during therapy; however, changes were observed in cancerous tissue, which was characterized by higher expression of MMP2 and MMP9, compared to non-cancerous tissue, and unchanged expression of TIMP1. Nevertheless, higher expression of each of the studied genes was associated with shorter patient survival. Interestingly, it was not only the increased expression of metalloproteinase genes, but also the increased expression of the metalloproteinase inhibitor (TIMP1) that was unfavorable for patients.

MiR-125b-5p/STAT3 Axis Regulates Drug Resistance in Osteosarcoma Cells by Acting on ABC Transporters

Background

The poor prognosis of the highly malignant tumor osteosarcoma stems from its drug resistance and therefore exploring its resistance mechanisms will help us identify more effective treatment options. However, the effects of miR-125b-5p on drug resistance in osteosarcoma cells are still unclear.

Methods

To study the effects of miR-125b-5p on drug resistance in osteosarcoma cells. Osteosarcoma-resistant miR-125b-5p was obtained from the databases GeneCards and g:Profiler. CCK8, western blot, and transwell were applied for the detection of the miR-125b-5p effects on proliferation, migration, invasion, apoptosis, and drug resistance in osteosarcoma. Bioinformatics is aimed at demonstrating the targeting factor miR-125b-5p, performing protein interaction enrichment analysis by Metascape, and finally validating by binding sites.

Results

Upregulation of miR-125b-5p restrains proliferation, migration, and invasion of osteosarcoma and promotes apoptosis. In addition, miR-125b-5p can restore drug sensitivity in drug-resistant osteosarcoma. miR-125-5p restrains the signal transducer and inhibits the transcription 3 (STAT3) expression activator via targeting its 3'-UTR. STAT3 affects drug-resistant osteosarcoma to regulate the ABC transporter.

Conclusion

miR-125b-5p/STAT3 axis mediates the drug resistance of osteosarcoma by acting on ABC transporter.

Comprehensive analysis of immune implication and prognostic value of DHX33 in sarcoma

DEAH-box helicase 33 (DHX33) is an RNA helicase that has been identified to promote the progression of a variety of cancers. However, the relationship between DHX33 and sarcoma remains unknown. RNA expression data with clinical information for the sarcoma project was collected from TCGA database. The association between the differential expression of DHX33 and the prognosis for sarcoma was assessed using survival analysis. CIBERSORT was used to evaluate the immune cell infiltration in sarcoma sample tissues. We then further investigated the association between DHX33 and tumor-infiltrating immune cells in sarcoma using the TIMER database. Finally, the immune/cancer-related signaling pathways involved in DHX33 were analyzed using gene set enrichment analysis. High DHX33 expression was discovered to be a poor prognostic indicator in TCGA-SARC. Immune subpopulations in the TCGA-SARC microenvironment are dramatically altered compared to normal tissues. The tumor immune estimation resource analysis revealed a strong correlation between the expression of DHX33 and the abundance of CD8+ T cells and dendritic cells. Changes in copy number also affected neutrophils, macrophages, and CD4+ T cells. According to gene set enrichment analysis, DHX33 may be involved in a number of cancer- and immune-related pathways, such as the JAK/STAT signaling pathway, P53 signaling pathway, chemokine signaling pathway, T cell receptor signaling pathway, complement and coagulation cascades, and cytokine-cytokine receptor interaction. Our study emphasized that DHX33 may be involved in the immune microenvironment of sarcoma and play an important role. As a result, it is possible that DHX33 might serve as an immunotherapeutic target for sarcoma.

Non-coding RNAs as potential biomarkers in osteosarcoma

Osteosarcoma (OS) is a primary solid malignant tumor that occurs most frequently in the metaphysis of long bones. More likely to happen to children and adolescents. OS has high mortality and disability rate. However, the etiology and pathogenesis of OS have not been fully understood till now. Due to the lack of effective biomarkers, OS cannot be precisely detected in the early stage. With the application of next-generation and high-throughput sequencing, more and more abnormally expressed non-coding RNAs(ncRNAs) have been identified in OS. Growing evidences have suggested the ncRNAs, such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), have played an important role in the tumorigenesis and progression of OS. Thus, they can be served as novel biomarkers for diagnosis, treatment and prognosis. This review summarized the application of ncRNA as biomarkers in OS in detail, and discussed the limitation and future improvement of the potential biomarkers.

Extracellular vesicles from bone mesenchymal stem cells transport microRNA-206 into osteosarcoma cells and target NRSN2 to block the ERK1/2-Bcl-xL signaling pathway

Osteosarcoma (OS) is a kind of malignant tumor originating from mesenchymal tissues. Bone mesenchymal stem cells-derived extracellular vesicles (BMSCs-EVs) can play important roles in OS. This study investigated the mechanism of BMSCs-EVs on OS. BMSC surface antigens and adipogenic and osteogenic differentiation were detected by flow cytometry, and oil red O and alizarin red staining. EVs were isolated from BMSCs by differential centrifugation and identified by transmission electron microscopy, nanoparticle tracking analysis, and Western blot (WB). miR-206 and neurensin-2 (NRSN2) levels in human osteoblast hFOB 1.19 or OS cells (143B, MG-63, Saos2, HOS) were detected by RT-qPCR. Human OS cells with lower miR-206 levels were selected and treated with BMSCs-EVs or pSUPER-NRSN2. The uptake of EVs by 143B cells, cell proliferation, apoptosis, invasion, and migration were detected by immunofluorescence, 5-ethynyl-2’-deoxyuridine (EdU) and colony formation assays, flow cytometry, scratch test, and transwell assays. The binding sites between miR-206 and NRSN2 were predicted by Starbase database and verified by dual-luciferase assay. The OS xenograft model was established and treated with BMSCs-EVs. Tumor growth rate and volume, cell proliferation, and p-ERK1/2, ERK1/2, and Bcl-xL levels were detected by vernier caliper, immunohistochemistry, and WB. BMSCs-EVs were successfully extracted. miR-206 was diminished and NRSN2 was promoted in OS cells. BMSCs-EVs inhibited proliferation, migration, and invasion, and promoted apoptosis of OS cells. BMSCs-EVs carried miR-206 into OS cells. Inhibition of miR-206 in EVs partially reversed the inhibitory effect of EVs on malignant behaviors of OS cells. miR-206 targeted NRSN2. Overexpression of NRSN2 reversed the inhibitory effect of EVs on OS cells. NRSN2 activated the ERK1/2-Bcl-xL pathway. BMSC-EVs inhibited OS growth in vivo. In summary, BMSC-EVs targeted NRSN2 and inhibited the ERK1/2-Bcl-xL pathway by carrying miR-206 into OS cells, thus inhibiting OS progression.

Cancer combination therapies by silencing of CTLA-4, PD-L1, and TIM3 in osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most common orthopedic neoplasm, with a high metastasis rate and a dismal prognosis despite surgery and chemotherapy. Immunotherapies have offered cancer patients a ray of optimism, but their impact on OS has been disappointing. The objective of this study is to assess the effect of mono, dual, and triple combinations of CTLA-4, PD-L1, and TIM3 blockade on OS cell viability, apoptosis, and migration.

METHOD

The MG-63 and U-2 OS cell lines were transfected with mono, dual, and triple combinations of siRNAs specific for CTLA-4, PD-L1, and TIM3. After evaluation for transfection efficacy by qRT-PCR, MTT assay and flow cytometry were applied to assess cell viability and apoptosis rate in siRNA-transfected cells, respectively. Ultimately, the migration of transfected cells was measured by wound healing assay.

RESULTS

First, the qRT-PCR analysis revealed that in siRNA-transfected OS cells, CTLA-4, PD-L1, and TIM3 were downregulated. The MTT assay and flow cytometry results confirmed that silencing of these immune checkpoints in dual or triple combinations, but not in the single-agent blockade, significantly decreases cell viability and increases apoptosis, respectively. These effects were more significant when triple silencing was performed. Finally, the wound healing assay revealed that dual and triple silencing of immune checkpoints significantly inhibit cell migration, with triple silencing exhibiting a greater effect.

CONCLUSION

Our findings suggest that triple blockade of CTLA-4, PD-L1, and TIM3 is an effective strategy for inhibiting tumor cell progression and migration in OS, which requires large-scale clinical investigations to be translated into broad therapeutic applicability for OS patients.

Prognostic significance and therapeutic potentials of immune checkpoints in osteosarcoma

Although there exist manifold strategies for cancer treatment, researchers are obliged to develop novel treatments based on the challenges that arise. One of these recent treatment approaches is cancer immunotherapy, which enjoys various types of strategies itself. However, one of the most significant methods, in this regard, is employing immune checkpoint proteins (ICPs). Bone sarcomas have several subtypes, with the most common ones being chordoma, chondrosarcoma, Ewing sarcoma, and osteosarcoma. Although many aggressive treatment approaches, including radiotherapy, chemotherapy, and surgical resection, have been employed over the last decades, significantly improved outcomes have not been observed for Ewing sarcoma or osteosarcoma patients. Additionally, chordoma and chdrosarcoma resist against both radiation and chemotherapy. Accordingly, elucidating how recent therapies could affect bone sarcomas is necessary. Checkpoint inhibitors have attracted great attention for the treatment of several cancer types, including bone sarcoma. Herein, the recent advances of current immune checkpoint targets, such as anti-PD-1/PD-L1 and anti-CTLA-4 blockade, for the treatment of bone sarcoma have been reviewed.

Overexpression of Long Non-Coding RNA MIR22HG Represses Proliferation and Enhances Apoptosis via miR-629-5p/TET3 Axis in Osteosarcoma Cells

In this study, we evaluated the mechanism of long non-coding RNA MIR22 host gene (LncRNA MIR22HG) in osteosarcoma cells. Forty-eight paired osteosarcoma and adjacent tissues samples were collected and the bioinformatic analyses were performed. Target genes and potential binding sites of MIR22HG, microRNA (miR)-629-5p and tet methylcytosine dioxygenase 3 (TET3) were predicted by Starbase and TargetScan V7.2 and confirmed by dual-luciferase reporter assay. Cell Counting Kit-8, colony formation and flow cytometry assays were utilized to determine the viability, proliferation and apoptosis of transfected osteosarcoma cells. Pearson's analysis was introduced for the correlation analysis between MIR22HG and miR-629-5p in osteosarcoma tissue. Relative expressions of MIR22HG, miR-629-5p and TET3 were measured by quantitative real-time polymerase chain reaction or Western blot. MiR-629-5p could competitively bind with and was negatively correlated with MIR22HG, the latter of which was evidenced by the high expression of miR-629-5p and low expression of MIR22HG in osteosarcoma tissues. Overexpressed MIR22HG repressed the viability and proliferation but enhanced apoptosis of osteosarcoma cells, which was reversed by miR-629-5p upregulation. TET3 was the target gene of miR-629-5p, and the promotive effects of upregulated miR-629-5p on the viability and proliferation as well as its repressive effect on apoptosis were abrogated via overexpressed TET3. To sum up, overexpressed MIR22HG inhibits the viability and proliferation of osteosarcoma cells, which was achieved via regulation of the miR-629-5p/TET3 axis.

miRNA-221-3p derived from M2-polarized tumor-associated macrophage exosomes aggravates the growth and metastasis of osteosarcoma through SOCS3/JAK2/STAT3 axis

Background: Enhanced infiltration of M2-polarized tumor-associated macrophages (TAMs) is linked to osteosarcoma (OS) metastasis and growth. Here, we aim to explore a novel miR-221-3p shuttled by M2-TAM exosomes in the growth and metastasis of OS cells.

Methods: THP-1 monocytes-derived M2-TAMs were induced by PMA/interleukin (IL)-4/IL-13 and then co-cultured with OS 143B and Saos2 cells. Overexpression or downregulation models of miR-221-3p were conducted to probe the impacts of exosome-derived M2-TAMs in OS cells. OS cell proliferative ability, colony formation, invasion, migration and apoptotic level were measured by the cell counting kit-8 (CCK-8) assay, colony formation, Transwell assay, and flow cytometry. Moreover, the SOCS3/JAK2/STAT3 axis in OS cells was testified by western blot, and a dual-luciferase reporter assay was conducted to confirm the link between miR-221-3p and SOCS3.

Results: OS cells enhanced M2 polarization of TAMs, which significantly promoted OS cells’ viability, colony formation, migration, invasion, and reduced apoptosis. Moreover, the exosomes enriched by miR-221-3p from M2-polarized TAMs (M2-TAMs) also aggravated the malignant behaviors of OS cells. However, down-regulation of miR-221-3p brought about contrary results. Further, in-vivo tests uncovered that overexpressing miR-221-3p enhanced OS cells’ growth. Mechanistically, SOCS3 was a downstream target of miR-221-3p, and up-regulation of miR-221-3p choked SOCS3 and activated JAK2/STAT3. However, the pharmacological intervention of the JAK2/STAT3 pathway obviously inhibited the malignant behaviors of OS cells, which were significantly reversed by miR-221-3p up-regulation.

Conclusion: The exosomal miR-221-3p derived from M2-TAMs aggravates OS progression via modulating the SOCS3/JAK2/STAT3 axis.

MicroRNAs Possibly Involved in the Development of Bone Metastasis in Clear-Cell Renal Cell Carcinoma

Simple Summary

Bone metastases cause substantial morbidity and implicate worse clinical outcomes for clear-cell renal cell carcinoma patients. MicroRNAs are small RNA molecules that modulate gene translation and are involved in the development of cancer and metastasis. We identified six microRNAs that are potentially specifically involved in metastasis to bone, of which two seem protective and four implicate a higher risk. This aids further understanding of the process of metastasizing to bone. Furthermore, these microRNA hold potential for biomarkers or therapeutic targets.

Abstract

Bone metastasis in clear-cell renal cell carcinoma (ccRCC) leads to substantial morbidity through skeletal related adverse events and implicates worse clinical outcomes. MicroRNAs (miRNA) are small non-protein coding RNA molecules with important regulatory functions in cancer development and metastasis. In this retrospective analysis we present dysregulated miRNA in ccRCC, which are associated with bone metastasis. In particular, miR-23a-3p, miR-27a-3p, miR-20a-5p, and miR-335-3p specifically correlated with the earlier appearance of bone metastasis, compared to metastasis in other organs. In contrast, miR-30b-3p and miR-139-3p were correlated with less occurrence of bone metastasis. These miRNAs are potential biomarkers and attractive targets for miRNA inhibitors or mimics, which could lead to novel therapeutic possibilities for bone targeted treatment in metastatic ccRCC.

Simultaneous microRNA-612 restoration and 5-FU treatment inhibit the growth and migration of human PANC-1 pancreatic cancer cells

Despite the recent advances in the treatment of other cancers, the 5-year survival rate of pancreatic cancer remains under 9 %. Chemotherapy and surgical resection are the most common therapy methods. The regulatory role of microRNAs in different types of cancer has given them therapeutic importance. miR-612 has been downregulated in colorectal, bladder, liver, and some other types of cancer and could be considered a tumor-suppressor miRNA. 5-FU is one of the most common chemotherapeutic agents used in pancreatic cancer treatment, which is used in multiple drug regimens and combinatorial therapy methods. The aim of this study is the evaluation of miR-612 restoration in the PANC-1 cell line and using the tumor-suppressive effect of it in combination with 5-FU on cell growth and migration. MiR-612 mimic was transfected to PANC-1 cells through electroporation. Following the transfection, expression levels of miR-612 and BAX, BCL-2, Caspase-3, MMP9, and PD-L1 genes were measured by qRT-PCR. MTT assay was used to determine the cytotoxicity of miR-612 and 5-FU on PANC-1 cell viability. To confirm MTT results and to evaluate the quantitative effect of apoptosis induction flow cytometry test was used and in order to confirm apoptosis test results and cell cycle arrest evaluation DAPI staining and cell, cycle tests were conducted, respectively. Finally, to assess the inhibitory effect of miR-612 in combination with 5-FU on migration and growth wound healing and colony formation assays were used, respectively. Results demonstrated that miR-612 alongside 5-FU has an important role in the inhibition of migration and growth and also apoptosis induction in PANC-1 cells and could be considered as a supporting agent of chemotherapy and a novel therapeutic modality in pancreatic cancer treatment.

[The regulatory role of microRNA in osteogenic differentiation of mesenchymal stem cells and its application as a therapeutic target and diagnostic tool in orthopedic diseases]

OBJECTIVE

To summarize the research progress of the regulatory role of microRNA (miRNA) in osteogenic differentiation of mesenchymal stem cells (MSCs) and its application as a therapeutic target and diagnostic tool in orthopedic diseases.

METHODS

The recent literature on the regulation of MSCs osteogenic differentiation by miRNAs was extensively reviewed, and its regulatory mechanism and its application as a therapeutic target and diagnostic tool in orthopedic diseases were reviewed.

RESULTS

miRNAs are small endogenous non-coding RNAs with a length of 20-22 nucleotides, which play an important role in the osteogenic differentiation of MSCs. Osteogenesis begins with the differentiation of MSCs into mature osteoblasts, and each stage of dynamic homeostasis of bone metabolism is associated with the regulation of different miRNAs. miRNAs are regulated from the post-transcriptional level by mRNAs cleavage, degradation, translational repression, or methylation. In addition, current studies suggest that miRNAs can be used as a new diagnostic tool and therapeutic target for orthopedic diseases.

CONCLUSION

Further study on the regulation mechanism of miRNAs will provide more ideas for finding new therapeutic targets and diagnostic tools for orthopedic disease.

Comprehensive Analysis of a ceRNA Network Identifies lncR-C3orf35 Associated with Poor Prognosis in Osteosarcoma

Osteosarcoma is a highly malignant bone cancer which primarily occurs in children and young adults. Increasing evidence indicates that long noncoding RNAs (lncRNAs), which function as competing endogenous RNAs (ceRNAs) that sponge microRNAs (miRNAs) and messenger RNAs (mRNAs), play a pivotal role in the pathogenesis and progression of cancers. The regulatory mechanisms of lncRNA-mediated ceRNAs in osteosarcoma have not been fully elucidated. In this study, we identified differentially expressed lncRNAs, miRNAs, and mRNAs in osteosarcoma based on RNA microarray profiles in the Gene Expression Omnibus (GEO) database. A ceRNA network was constructed utilizing bioinformatic tools. Kaplan-Meier survival analysis showed that lncR-C3orf35 and HMGB1 were associated with poor prognosis of osteosarcoma patients. Furthermore, results of Gene Set Enrichment Analysis (GSEA) suggested that lncR-C3orf35 may be involved in cellular invasion, the Toll-like receptor signaling pathway, and immune cell infiltration in the tumor microenvironment. Further analysis showed that patients with osteosarcoma metastasis expressed higher levels of lncR-C3orf35 and HMGB1 compared to metastasis-free patients. Moreover, the metastasis-free survival rate of the high lncR-C3orf35/HMGB1 expression group was significantly lower than that of the low expression group. The ESTIMATE algorithm was used to calculate the immune score and stromal scores for each sample. High lncR-C3orf35 and HMGB1 levels were correlated with low immune scores. ImmuCellAI analysis revealed that a low proportion of macrophage infiltration was associated with high lncR-C3orf35 and HMGB1 expression. The differential expression of lncR-C3orf35, miR-142-3p, and HMGB1 was further verified by quantitative real-time PCR. This study indicates that lncR-C3orf35 could be considered as a novel potential biomarker and therapeutic target of osteosarcoma, which may contribute to a better understanding of ceRNA regulatory mechanisms.

Downregulated Long Non-Coding RNA MSC-AS1 Inhibits Osteosarcoma Progression and Increases Sensitivity to Cisplatin by Binding to MicroRNA-142

Background

Osteosarcoma (OS) is the most prevalent malignant primary bone tumor, resulting from severe transformation of primitive mesenchymal cells, which induces osteogenesis. Long non-coding RNA (lncRNA) MSC-AS1 triggers osteogenic differentiation by sponging microRNA (miR)-140-5p. The present study assessed the mechanism of lncRNA MSC-AS1 in OS biological features and sensitivity to cisplatin (DDP) by binding to miR-142.

Material/Methods

Firstly, lncRNA MSC-AS1 expression in OS tissues and cells was analyzed. OS cells were transfected with silenced MSC-AS1 to determine its role in OS biological behaviors, and we also assessed the effect of MSC-AS1 on OS sensitivity to DDP. Then, website prediction and dual-luciferase reporter gene assay were utilized for verification of the binding site between MSC-AS1 and miR-142. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis were performed to determine the effect of MSC-AS1 on expression of miR-142, cyclin-dependent kinase 6 (CDK6), and the PI3K/AKT signaling pathway. Xenograft transplantation was also applied to confirm the in vitro experiments.

Results

Overexpressed MSC-AS1 was associated with poor prognosis of OS patients. OS cell proliferation, invasion, and migration were reduced after silencing MSC-AS1, while cell apoptosis was enhanced. Moreover, silencing MSC-AS1 made OS cells more sensitive to DDP. Interestingly, MSC-AS1 knockdown induced miR-142 expression and reduced CDK6 levels, thereby decreasing the protein expression of p-PI3K/t-PI3K and p-AKT/t-AKT. Silencing MSC-AS1 repressed OS progression in vivo.

Conclusions

Our study demonstrated that silencing MSC-AS1 inhibited OS biological behaviors by enhancing miR-142 to decrease CDK6 and inactivating the PI3K/AKT axis. Our results may provide new insights for OS treatment.

Prospects for the involvement of cancer stem cells in the pathogenesis of osteosarcoma

Osteosarcoma (OS) is one of the most common bone tumors in children and adolescents that cause a high rate of mortality in this age group and tends to be metastatic, in spite of chemotherapy and surgery. The main reason for this can be returned to a small group of malignant cells called cancer stem cells (CSCs). OS-CSCs play a key role in the resistance to treatment and relapse and metastasis through self-renewal and differentiation abilities. In this review, we intend to go through the different aspects of this malignant disease, including the cancer stem cell-phenotype, methods for isolating CSCs, signaling pathways, and molecular markers in this disease, and drugs showing resistance in treatment efforts of OS.

Identification of critical genes associated with human osteosarcoma metastasis based on integrated gene expression profiling

Osteosarcoma is the most common type of malignant bone cancer, which often affects teenagers and young adults. The present study aimed to screen for critical genes and microRNAs (miRNAs/miRs) involved in osteosarcoma. A total of four microarray datasets (accession numbers GSE32981, GSE21257, GSE14827 and GSE14359) were downloaded from the Gene Expression Omnibus database. Following data preprocessing, module analysis was performed to identify the stable modules using the weighted gene co‑expression network analysis (WGCNA) package. The differentially expressed genes (DEGs) between metastatic samples and non‑metastatic samples were screened, followed by gene co‑expression network construction, and Gene Ontology function and Kyoto Encyclopedia of Genes and Genomes pathway analyses. Subsequently, prognosis‑associated genes were screened and a miRNA‑target gene regulatory network was constructed. Finally, the data for critical genes were validated. WGCNA analysis identified six modules; blue and yellow modules were significantly positively associated with osteosarcoma metastasis. A total of 1,613 DEGs were screened between primary tissue samples and metastatic samples. Following comparison of the genes in the two (blue and yellow) modules, a total of 166 DEGs were identified (metastatic samples vs. non‑metastatic samples). Functional enrichment analysis demonstrated that these DEGs were mainly involved in 'defense response', 'p53 signaling pathway' and 'lysosome'. By utilizing the clinical information in GSE21257, 10 critical genes associated with osteosarcoma prognosis were obtained, including CTP synthase 2 (CTPS2), tumor protein p53 inducible protein 3 (TP53I3) and solute carrier family 1 member 1 (SLC1A1). In addition, hsa‑miR‑422a and hsa‑miR‑194 were highlighted in the miRNA‑target gene network. Finally, matrix metallopeptidase 3 (MMP3) and vascular endothelial growth factor B (VEGFB) were predicted as critical genes in osteosarcoma metastasis. CTPS2, TP53I3 and SLC1A1 may serve major roles in osteosarcoma development, and hsa‑miR‑422a, hsa‑miR‑194, MMP3 and VEGFB may be associated with osteosarcoma metastasis.