Drugs in early clinical development for the treatment of osteosarcoma

Cancer Stem Cells in Sarcomas: In Vitro Isolation and Role as Prognostic Markers: A Systematic Review

Sarcomas are a diverse group of neoplasms with an incidence rate of 15% of childhood cancers. They exhibit a high tendency to develop early metastases and are often resistant to available treatments, resulting in poor prognosis and survival. In this context, cancer stem cells (CSCs) have been implicated in recurrence, metastasis, and drug resistance, making the search for diagnostic and prognostic biomarkers of the disease crucial. The objective of this systematic review was to analyze the expression of CSC biomarkers both after isolation from in vitro cell lines and from the complete cell population of patient tumor samples. A total of 228 publications from January 2011 to June 2021 was retrieved from different databases, of which 35 articles were included for analysis. The studies demonstrated significant heterogeneity in both the markers detected and the CSC isolation techniques used. ALDH was identified as a common marker in various types of sarcomas. In conclusion, the identification of CSC markers in sarcomas may facilitate the development of personalized medicine and improve treatment outcomes.

Psoralidin inhibits osteosarcoma growth and metastasis by downregulating ITGB1 expression via the FAK and PI3K/Akt signaling pathways

BACKGROUND

Psoralea corylifolia is a medicinal leguminous plant that has long been used to treat various diseases. Psoralidin (PSO) is the main extract compound of P. corylifolia and exhibits antibacterial, antitumor, anti-inflammatory, antioxidant, and other pharmacological activities. PSO has demonstrated inhibitory effects in several cancers; however, its inhibitory effect on osteosarcoma has not been reported. This study aimed to evaluate the inhibitory effect of PSO on osteosarcoma and elucidate the underlying molecular mechanisms.

METHODS

Crystal violet, cell counting kit-8 (CCK8), and 5-Ethynyl-2'-deoxyuridine (EdU) staining assays were used to assess the inhibitory effect of PSO on the proliferation of 143B and MG63 osteosarcoma cells. Wound healing and Transwell assays were conducted to evaluate the effects of PSO on osteosarcoma cell migration and invasion. The cell cycle and apoptosis were analyzed using flow cytometry. To determine the possible molecular mechanisms, RNA-sequencing was performed and protein expression was analyzed by western blotting. The inhibitory effect of PSO on osteosarcoma in vivo was analyzed using a mouse model of orthotopic osteosarcoma and immunohistochemistry.

RESULTS

PSO inhibited osteosarcoma cell proliferation in a concentration-dependent manner, inhibited cell migration and invasion, and induced cell-cycle arrest and apoptosis. Mechanistically, PSO treatment significantly inhibited the focal adhesion kinase (FAK) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways by downregulating ITGB1 expression in both MG63 and 143B cells. Furthermore, we demonstrated that PSO restrained osteosarcoma growth in vivo.

CONCLUSION

PSO may suppress osteosarcoma via the FAK and PI3K/Akt signaling pathways by downregulating ITGB1 expression.

The emerging applications and advancements of Raman spectroscopy in pediatric cancers

Although the survival rate of pediatric cancer has significantly improved, it is still an important cause of death among children. New technologies have been developed to improve the diagnosis, treatment, and prognosis of pediatric cancers. Raman spectroscopy (RS) is a non-destructive analytical technique that uses different frequencies of scattering light to characterize biological specimens. It can provide information on biological components, activities, and molecular structures. This review summarizes studies on the potential of RS in pediatric cancers. Currently, studies on the application of RS in pediatric cancers mainly focus on early diagnosis, prognosis prediction, and treatment improvement. The results of these studies showed high accuracy and specificity. In addition, the combination of RS and deep learning is discussed as a future application of RS in pediatric cancer. Studies applying RS in pediatric cancer illustrated good prospects. This review collected and analyzed the potential clinical applications of RS in pediatric cancers.

Heparin and Heparin-Based Drug Delivery Systems: Pleiotropic Molecular Effects at Multiple Drug Resistance of Osteosarcoma and Immune Cells

One of the main problems of modern health care is the growing number of oncological diseases both in the elderly and young population. Inadequately effective chemotherapy, which remains the main method of cancer control, is largely associated with the emergence of multidrug resistance in tumor cells. The search for new solutions to overcome the resistance of malignant cells to pharmacological agents is being actively pursued. Another serious problem is immunosuppression caused both by the tumor cells themselves and by antitumor drugs. Of great interest in this context is heparin, a biomolecule belonging to the class of glycosaminoglycans and possessing a broad spectrum of biological activity, including immunomodulatory and antitumor properties. In the context of the rapid development of the new field of “osteoimmunology,” which focuses on the collaboration of bone and immune cells, heparin and delivery systems based on it may be of intriguing importance for the oncotherapy of malignant bone tumors. Osteosarcoma is a rare but highly aggressive, chemoresistant malignant tumor that affects young adults and is characterized by constant recurrence and metastasis. This review describes the direct and immune-mediated regulatory effects of heparin and drug delivery systems based on it on the molecular mechanisms of (multiple) drug resistance in (onco) pathological conditions of bone tissue, especially osteosarcoma.

Origin and Therapies of Osteosarcoma

Simple Summary

Osteosarcoma is the most common malignant bone tumor in children, with a 5-year survival rate ranging from 70% to 20% depending on the aggressiveness of the disease. The current treatments have not evolved over the past four decades due in part to the genetic complexity of the disease and its heterogeneity. This review will summarize the current knowledge of OS origin, diagnosis and therapies.

Abstract

Osteosarcoma (OS) is the most frequent primary bone tumor, mainly affecting children and young adults. Despite therapeutic advances, the 5-year survival rate is 70% but drastically decreases to 20–30% for poor responders to therapies or for patients with metastasis. No real evolution of the survival rates has been observed for four decades, explained by poor knowledge of the origin, difficulties related to diagnosis and the lack of targeted therapies for this pediatric tumor. This review will describe a non-exhaustive overview of osteosarcoma disease from a clinical and biological point of view, describing the origin, diagnosis and therapies.

SOX9 and SATB2 Immunohistochemistry Cannot Reliably Distinguish Between Osteosarcoma and Chondrosarcoma on Biopsy Material

INTRODUCTION

Limited tissue in biopsies of malignant bone lesions can preclude definitive subclassification, especially when cellular or matrix elements are sparse, absent, or confounding. It is uncertain whether IHC for SOX9 (marker of chondrogenesis) and SATB2 (marker of osteoblastic differentiation) may be discriminatory tools towards osteosarcoma and chondrosarcoma.

METHODS

This study interrogated the pre-resection biopsies of a cohort of osteosarcoma and chondrosarcoma with SATB2 and SOX9 in tandem, to assess their value as diagnostic adjuncts as well as their concordance with final resection diagnoses.

RESULTS

SATB2 was expressed more frequently in osteosarcoma (46/53, 86%) compared to chondrosarcoma (9/18, 50%); SOX9 was expressed in high frequencies in both osteosarcoma (52/53, 98%) and chondrosarcoma (17/18, 94%), and SATB2 and SOX9 were co-expressed in both osteosarcoma (46/53, 89%) and chondrosarcoma (8/18, 44%).

CONCLUSIONS

There exists significant overlap in expression of SATB2 and SOX9 in osteosarcoma and chondrosarcoma. These markers are not expressed in a distribution that is unique enough for application towards this particular diagnostic differential.

The Effect of miR-138 on the Function of Follicular Helper T Cells and the Differentiation of B Cells in Osteosarcoma

OBJECTIVE

To explore the effect of miR-138 on the function of follicular helper T (Tfh) cells and the differentiation of B cells in osteosarcoma.

METHODS

Clinically collect peripheral blood from osteosarcoma (OS) patients and healthy volunteers (HC), as well as OS tumor tissues (OS tumor) and adjacent tissues with normal histology (normal group). The CD4+CXCR5+Tfh cells of OS patients were screened and isolated by flow cytometry, and the expression of Tfh cell membrane surface antigens PD-1 and CTLA-4 was detected. In addition, qRT-PCR was used to detect the expression of miR-138 in tissues and Tfh cells, and the correlation relationship between miR-138 and PD-1 and CTLA-4 was analyzed. After interference or overexpression of miR-138 in Tfh cells, coculture with untreated B cells was done, and the levels of IL-10, IL-12, IL-21, and INF-γ in Tfh cell culture medium and the levels of IgM, IgG, and IgA in B cell culture medium after coculture were measured by ELISA. Flow cytometry was used to detect the expression of B cell membrane surface antigens CD27 and CD38 after coculture.

RESULTS

The rate of PD-1- and CTLA-4 positive cells in the peripheral blood and tissues of the OS group was significantly increased, the expression of miR-138 was significantly reduced, and the expression of miR-138 was negatively correlated with the expression of PD-1 and CTLA-4. In addition, upregulation of miR-138 can lead to a significant increase in the level of IL-10 in the supernatant of Tfh cells and a significant decrease in the levels of IL-12, IL-21, and INF-γ, which in turn leads to increased levels of IgM, IgG, and IgA released by B cells. At the same time, it significantly increases the rate of CD27- and CD38-positive cells and promotes the maturation of B cells. Downregulating miR-138 has the opposite effect.

CONCLUSION

Downregulating the expression of miR-138 in osteosarcoma can improve the dysfunction of CD4+CXCR5+Tfh cells and promote the differentiation of B cells.

Tetrandrine suppresses the growth of human osteosarcoma cells by regulating multiple signaling pathways

Although osteosarcoma (OS) is the most common malignant tumor among juvenile bone tumors, its treatment plan and clinical outcome have not improved significantly in recent decades. Tetrandrine (TET), a Chinese medicine that is usually used in the therapy of silicosis, hypertension and arthritis, has been confirmed by many studies to possess potent antitumour growth properties, but there are different limitations when describing specific mechanisms. Here, we found that TET can obviously prevent the proliferation, migration and invasion of both 143B and MG63 cells and promote their apoptosis in vitro. Our results for luciferase reporter and Western blotting assays show that TET may exert its antitumour activity by regulating multiplex signaling pathways, including the MAPK/Erk, PTEN/Akt, Juk and Wnt signaling pathways. Furthermore, the regulatory effect of TET on OS cells and related signaling pathways was verified again in vivo. Our findings suggest that the anticancer function of TET on human OS may be mediated by its targeting of multiple signaling pathways and that TET may be used as a single drug or in combination with other drugs during the treatment of OS.

The smac mimetic LCL161 targets established pulmonary osteosarcoma metastases in mice

Osteosarcoma is the most common form of primary bone cancer and frequently metastasizes to the lungs. Current therapies fail to successfully treat over two thirds of patients with metastatic osteosarcoma, so there is an urgent imperative to develop therapies that effectively target established metastases. Smac mimetics are drugs that work by inhibiting the pro-survival activity of IAP proteins such as cIAP1 and cIAP2, which can be overexpressed in osteosarcomas. In vitro, osteosarcoma cells are sensitive to a range of Smac mimetics in combination with TNFα. This sensitivity has also been demonstrated in vivo using the Smac mimetic LCL161, which inhibited the growth of subcutaneous and intramuscular osteosarcomas. Here, we evaluated the efficacy of LCL161 using mice bearing osteosarcoma metastases without the presence of a primary tumor, modeling the scenario in which a patient's primary tumor had been surgically removed. We demonstrated the ability of LCL161 as a single agent and in combination with doxorubicin to inhibit the growth of, and in some cases eliminate, established pulmonary osteosarcoma metastases in vivo. Resected lung metastases from treated and untreated mice remained sensitive to LCL161 in combination with TNFα ex vivo. This suggested that there was little to no acquired resistance to LCL161 treatment in surviving osteosarcoma cells and implied that tumor microenvironmental factors underlie the observed variation in responses to LCL161.

Acid Microenvironment in Bone Sarcomas

Simple Summary

Although rare, malignant bone sarcomas have devastating clinical implications for the health and survival of young adults and children. To date, efforts to identify the molecular drivers and targets have focused on cancer cells or on the interplay between cancer cells and stromal cells in the tumour microenvironment. On the contrary, in the current literature, the role of the chemical-physical conditions of the tumour microenvironment that may be implicated in sarcoma aggressiveness and progression are poorly reported and discussed. Among these, extracellular acidosis is a well-recognized hallmark of bone sarcomas and promotes cancer growth and dissemination but data presented on this topic are fragmented. Hence, we intended to provide a general and comprehensive overview of the causes and implications of acidosis in bone sarcoma.

Abstract

In bone sarcomas, extracellular proton accumulation is an intrinsic driver of malignancy. Extracellular acidosis increases stemness, invasion, angiogenesis, metastasis, and resistance to therapy of cancer cells. It reprograms tumour-associated stroma into a protumour phenotype through the release of inflammatory cytokines. It affects bone homeostasis, as extracellular proton accumulation is perceived by acid-sensing ion channels located at the cell membrane of normal bone cells. In bone, acidosis results from the altered glycolytic metabolism of bone cancer cells and the resorption activity of tumour-induced osteoclasts that share the same ecosystem. Proton extrusion activity is mediated by extruders and transporters located at the cell membrane of normal and transformed cells, including vacuolar ATPase and carbonic anhydrase IX, or by the release of highly acidic lysosomes by exocytosis. To date, a number of investigations have focused on the effects of acidosis and its inhibition in bone sarcomas, including studies evaluating the use of photodynamic therapy. In this review, we will discuss the current status of all findings on extracellular acidosis in bone sarcomas, with a specific focus on the characteristics of the bone microenvironment and the acid-targeting therapeutic approaches that are currently being evaluated.

Co-delivery of doxorubicin and paclitaxel by reduction/pH dual responsive nanocarriers for osteosarcoma therapy

Nanoparticle-based drug delivery system offers a promising platform for combination cancer therapy. However, the inefficient drug release in cells reduces the therapeutic efficacy of cancer nanomedicines. Herein, a PEGylated poly(α-lipoic acid) copolymer (mPEG-PαLA) was prepared and used as a reduction/pH dual responsive nanocarrier to simultaneously deliver paclitaxel (PTX) and doxorubicin (DOX) for osteosarcoma therapy. The amphiphilic mPEG-PαLA could efficiently encapsulate both PTX and DOX during its self-assembly into micelles in aqueous solution to generate PTX and DOX co-loaded nanoparticles (NP-PTX-DOX). The as-prepared NP-PTX-DOX showed enhanced PTX and DOX release in response to reductive and acidic stimuli. Moreover, the dual-drug loaded nanoparticles were efficiently internalized by K7 osteosarcoma cells and released drugs intracellularly, as confirmed by flow cytometry analysis and confocal laser scanning microscopy. Consequently, NP-PTX-DOX exhibited synergistic therapeutic effects and induced enhanced cell apoptosis in K7 cells. Furthermore, NP-PTX-DOX presented improved biodistribution and higher tumor growth inhibition efficacy compared to the control groups in a murine osteosarcoma model. Altogether, the results of this work indicate that the proposed strategy is promising for osteosarcoma therapy using mPEG-PαLA copolymer as a dual-responsive nanocarrier to co-deliver anticancer drugs.

Silencing of the Long Non-Coding RNA TTN-AS1 Attenuates the Malignant Progression of Osteosarcoma Cells by Regulating the miR-16-1-3p/TFAP4 Axis

Objectives

Osteosarcoma (OS) is a type of bone malignancy. This study attempted to explore the effect of long non-coding RNA TTN-AS1 (TTN-AS1) on OS and to determine its molecular mechanisms.

Methods

The expression of TTN-AS1, microRNA-16-1-3p (miR-16-1-3p), and transcription factor activating enhancer binding protein 4 (TFAP4) in OS was assessed using qRT-PCR. The OS cell proliferation, migration, and invasion were measured using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), wound-healing, and transwell assays. N-cadherin and MMP-2 protein level was determined with western blot. Interactions between TTN-AS1 and miR-16-1-3p or TFAP4 and miR-16-1-3p were confirmed using the dual-luciferase reporter assay. Additionally, an OS xenograft tumor model was constructed to assess the effect of TTN-AS1 on tumor growth.

Results

TTN-AS1 and TFAP4 expression was increased in OS, while miR-16-1-3p expression was decreased. TTN-AS1 silencing restrained OS cell proliferation, migration, invasion, N-cadherin and MMP-2 protein expression, and hindered tumor growth. MiR-16-1-3p overexpression retarded the malignant behavior of OS cells. TTN-AS1 played a carcinostatic role by down-regulating miR-16-1-3p in the OS cells. Moreover, miR-16-1-3p inhibition or TFAP4 elevation weakened the suppressive effect of TTN-AS1 silencing on OS cell tumor progression.

Conclusion

TTN-AS1 promoted the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of OS cells via mediating the miR-16-1-3p/TFAP4 axis. TTN-AS1 may be a critical target for improving OS.

Heterogeneous Circulating Tumor Cells in Sarcoma: Implication for Clinical Practice

Simple Summary

The present review is aimed to discuss the relevance of assaying for the presence and isolation of circulating tumor cells (CTCs) in patients with sarcoma. Just a few studies have been performed to detect and enumerate viable CTCs in sarcoma and a majority of them still represent proof-of-concept studies, while more frequently tumor cells have been detected in the circulation by using the PCR-based method. Nevertheless, recent advances in technologies allowed detection of epithelial–mesenchymal transitioned CTCs from patients with mesenchymal malignancies, despite results being mostly preliminary. The possibility to identify CTCs holds a great promise for both applications of liquid biopsy in sarcoma for precision medicine, and for research purposes to pinpoint the mechanism of the metastatic process through the characterization of tumor mesenchymal cells. Coherently, clinical trials in sarcoma have been designed accordingly to detect CTCs, for diagnosis, identification of novel therapeutic targets and resistance mechanisms of systemic therapies, and patient stratification.

Abstract

Bone and soft tissue sarcomas (STSs) represent a group of heterogeneous rare malignant tumors of mesenchymal origin, with a poor prognosis. Due to their low incidence, only a few studies have been reported addressing circulating tumor cells (CTCs) in sarcoma, despite the well-documented relevance for applications of liquid biopsy in precision medicine. In the present review, the most recent data relative to the detection and isolation of viable and intact CTCs in these tumors will be reviewed, and the heterogeneity in CTCs will be discussed. The relevance of epithelial–mesenchymal plasticity and stemness in defining the phenotypic and functional properties of these rare cells in sarcoma will be highlighted. Of note, the existence of dynamic epithelial–mesenchymal transition (EMT)-related processes in sarcoma tumors has only recently been related to their clinical aggressiveness. Also, the presence of epithelial cell adhesion molecule (EpCAM)-positive CTC in sarcoma has been weakly correlated with poor outcome and disease progression, thus proving the existence of both epithelial and mesenchymal CTC in sarcoma. The advancement in technologies for capturing and enumerating all diverse CTCs phenotype originating from these mesenchymal tumors are presented, and results provide a promising basis for clinical application of CTC detection in sarcoma.

Role of microRNAs in the crosstalk between osteosarcoma cells and the tumour microenvironment

Osteosarcoma (OS) is the most common primary bone tumour, with a peak incidence in adolescents, and the five-year survival rate of patients with metastasis or recurrence is much lower than that of patients without metastasis and recurrence. OS is initiated and develops in a complex tumour microenvironment (TME) that contains many different components, such as osteoblasts, osteoclasts, mesenchymal stem cells, fibroblasts, immune cells, extracellular matrix (ECM), extracellular vesicles, and cytokines. The extensive interaction between OS and the TME underlies OS progression. Therefore, rather than targeting OS cells, targeting the key factors in the TME may yield novel therapeutic approaches. MicroRNAs (miRNAs) play multiple roles in the biological behaviours of OS, and recent studies have implied that miRNAs are involved in mediating the communication between OS cells and the surrounding TME. Here, we review the TME landscape and the miRNA dysregulation of OS, describe the role of the altered TME in OS development and highlight the role of miRNA in the crosstalk between OS cells and the TME.

Circulating Tumor Cells and Biomarker Modulation with Olaratumab Monotherapy Followed by Olaratumab plus Doxorubicin: Phase Ib Study in Patients with Soft-Tissue Sarcoma

This phase Ib study enumerated whole blood circulating tumor cells (CTC) and evaluated biomarkers in patients with potentially resectable soft-tissue sarcoma (STS) treated with olaratumab monotherapy (20 mg/kg) for one cycle followed by up to six cycles of olaratumab (20 mg/kg, cycles 1-2; 15 mg/kg, cycles 3-7) plus doxorubicin (75 mg/m² on day 1). CTCs, platelet-derived growth factor receptors (PDGFR), and PDGF ligand expression in tumor tissue pre- and post-olaratumab monotherapy were evaluated. Antitumor activity, safety, pharmacokinetics, and PET/biomarker association with clinical outcome were assessed. Of 51 treated patients, 35, 43, and 37 were evaluable for CTC enumeration, PDGFRs, and PDGF ligand expression, respectively. An increase in CTCs at cycle 1 day 8 was observed, followed by a significant reduction by cycle 3 day 1 or 30-day follow-up. Decrease in CTC counts after olaratumab monotherapy was higher in patients with disease control than without disease control (57.9% vs. 31.2%). Baseline IHC expression was positive in most patients for PDGFRα [n = 31 (72.1%)] and PDGFRβ [n = 36 (83.7%)]. Similar rates were observed post-olaratumab monotherapy [PDGFRα, n = 30 (69.8%); PDGFRβ, n = 33 (76.7%)]. Eleven patients (29.7%) showed a 30% reduction by RT-PCR in PDGFRα at cycle 2. PDGFR expression and PET response showed no correlation with clinical outcome. Safety and pharmacokinetic profiles were consistent with previous reports. This study, the first to use a validated method for CTC detection, confirms that CTC enumeration in STS is feasible. However, no correlation was observed between PDGFRα expression and clinical outcome.

Tumor-Associated Macrophages in Osteosarcoma: From Mechanisms to Therapy

Osteosarcomas (OSs) are bone tumors most commonly found in pediatric and adolescent patients characterized by high risk of metastatic progression and recurrence after therapy. Effective therapeutic management of this disease still remains elusive as evidenced by poor patient survival rates. To achieve a more effective therapeutic management regimen, and hence patient survival, there is a need to identify more focused targeted therapies for OSs treatment in the clinical setting. The role of the OS tumor stroma microenvironment plays a significant part in the development and dissemination of this disease. Important components, and hence potential targets for treatment, are the tumor-infiltrating macrophages that are known to orchestrate many aspects of OS stromal signaling and disease progression. In particular, increased infiltration of M2-like tumor-associated macrophages (TAMs) has been associated with OS metastasis and poor patient prognosis despite currently used aggressive therapies regimens. This review aims to provide a summary update of current macrophage-centered knowledge and to discuss the possible roles that macrophages play in the process of OS metastasis development focusing on the potential influence of stromal cross-talk signaling between TAMs, cancer-stem cells and additional OSs tumoral microenvironment factors.

Piperlongumine induces apoptosis and G2/M phase arrest in human osteosarcoma cells by regulating ROS/PI3K/Akt pathway

Previous research has reported that piperlongumine exerts antitumor properties on several types of tumor cells. However, its effect on osteosarcoma cells remains unknown. This study aimed to investigate the antitumor effects of piperlongumine on osteosarcoma cells (MG63 and U2OS cells) in vitro and determined the underlying mechanism. Cell viability was measured using MTT assay. Cell apoptosis was assessed via AO/EB staining and flow cytometry apoptosis as well as western blot analysis. Cell cycle distribution was detected by flow cytometric cell cycle and western blot analysis. In our research, we found that piperlongumine induced apoptosis and G2/M phase arrest of MG63 cells. Western blot analysis not only confirmed the above results, but also demonstrated that piperlongumine induced apoptosis of osteosarcoma cells by activating Caspase-9-dependent apoptotic pathway. Furthermore, we also found that piperlongumine significantly induced apoptosis and cell cycle arrest of osteosarcoma cells by regulating ROS/PI3K/Akt signaling pathway. In summary, our findings suggested that piperlongumine inhibited osteosarcoma progression by promoting apoptosis of osteosarcoma cells. In addition, the underlying mechanism demonstrated that piperlongumine produced potent antitumor properties in osteosarcoma cells by regulating ROS/PI3K/Akt signaling pathway.

A novel risk score model based on eight genes and a nomogram for predicting overall survival of patients with osteosarcoma

BACKGROUND

This study aims to identify a predictive model to predict survival outcomes of osteosarcoma (OS) patients.

METHODS

A RNA sequencing dataset (the training set) and a microarray dataset (the validation set) were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database, respectively. Differentially expressed genes (DEGs) between metastatic and non-metastatic OS samples were identified in training set. Prognosis-related DEGs were screened and optimized by support vector machine (SVM) recursive feature elimination. A SVM classifier was built to classify metastatic and non-metastatic OS samples. Independent prognosic genes were extracted by multivariate regression analysis to build a risk score model followed by performance evaluation in two datasets by Kaplan-Meier (KM) analysis. Independent clinical prognostic indicators were identified followed by nomogram analysis. Finally, functional analyses of survival-related genes were conducted.

RESULT

Totally, 345 DEGs and 45 prognosis-related genes were screened. A SVM classifier could distinguish metastatic and non-metastatic OS samples. An eight-gene signature was an independent prognostic marker and used for constructing a risk score model. The risk score model could separate OS samples into high and low risk groups in two datasets (training set: log-rank p < 0.01, C-index = 0.805; validation set: log-rank p < 0.01, C-index = 0.797). Tumor metastasis and RS model status were independent prognostic factors and nomogram model exhibited accurate survival prediction for OS. Additionally, functional analyses of survival-related genes indicated they were closely associated with immune responses and cytokine-cytokine receptor interaction pathway.

CONCLUSION

An eight-gene predictive model and nomogram were developed to predict OS prognosis.

USF1-mediated upregulation of lncRNA GAS6-AS2 facilitates osteosarcoma progression through miR-934/BCAT1 axis

Long noncoding RNAs (lncRNAs) have been certified as important regulators in tumorigenesis. LncRNA GAS6-AS2 (GAS6-AS2) was a newly identified tumor-related lncRNA, and its dysregulation and oncogenic effects in melanoma and bladder cancer had been reported in previous studies. However, the expression pattern and potential function of GAS6-AS2 in osteosarcoma (OS) have not been investigated. In this study, we identified a novel OS-related lncRNA GAS6-AS2. We found that GAS6-AS2 was distinctly upregulated in both OS specimens and cell lines. Distinct up-regulation of GAS6-AS2 in OS was correlated with advanced clinical stages and shorter survivals. In addition, USF1 could directly bind to the GAS6-AS2 promoter and contribute to its overexpression. Furthermore, GAS6-AS2 knockdown caused tumor suppressive effects via reducing cellular proliferation, migration and invasion, and promoting OS cell apoptosis. Besides, GAS6-AS2 directly bound to miR-934 and downregulated its expression. Mechanistically, GAS6-AS2 positively regulated the expression of BCAT1 through sponging miR-934. Taken together, our data illustrated how GAS6-AS2 played an oncogenic role in OS and might offer a potential therapeutic target for treating OS.

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

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

Bone sarcomas in the immunotherapy era

Bone sarcomas are primary bone tumours found mainly in children and adolescents, as osteosarcoma and Ewing's sarcoma, and in adults in their 40s as chondrosarcoma. The last four decades the development of therapeutic approaches was based on drug combinations have shown no real improvement in overall survival. Recently oncoimmunology has allowed a better understand of the crucial role played by the immune system in the oncologic process. This led to clinical trials with the aim of reprogramming the immune system to facilitate cancer cell recognition. Immune infiltrates of bone sarcomas have been characterized and their molecular profiling identified as immune therapeutic targets. Unfortunately, the clinical responses in trials remain anecdotal but highlight the necessity to improve the characterization of tumour micro-environment to unlock the immunotherapeutic response, especially in their paediatric forms. Bone sarcomas have entered the immunotherapy era and here we overview the recent developments in immunotherapies in these sarcomas. LINKED ARTICLES: This article is part of a themed issue on The molecular pharmacology of bone and cancer-related bone diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.9/issuetoc.

MicroRNA-99b predicts clinical outcome of osteosarcoma and suppresses tumor cell proliferation, migration and invasion

BACKGROUND

Osteosarcoma (OS) is a malignancy predominantly occurred in children and adolescents. Numerous microRNAs are involved in the pathogenesis of various cancers. This study aimed to investigate the expression profiles of miR-99b and its prognostic value in OS patients, and further analyze the biological function of miR-99b in the tumor progression by using OS cells.

METHODS

Expression of miR-99b was measured using quantitative real-time PCR. Kaplan-Meier survival curves and Cox regression analysis were performed to evaluate the prognostic value of miR-99b. OS cell lines were used to investigate the effects of miR-99b on cell proliferation, migration and invasion.

RESULTS

A significant decreased expression of miR-99b was observed in the OS tissues and cell lines respectively compared with the normal tissues and cells. Aberrant expression of miR-99b was associated with the patients' metastasis and TNM stage, and could be used to predict the prognosis of OS. The expression of miR-99b was regulated in vitro by cell transfection, and we found that the overexpression of miR-99b led to suppressed cell proliferation, migration and invasion, whereas the knockdown of miR-99b resulted in the opposite results.

CONCLUSIONS

In one word, the aberrantly expressed miR-99b serves a prognostic biomarker for OS patients. OS cell proliferation, migration and invasion can be inhibited by the overexpression of miR-99b, suggesting that the methods to increase miR-99b expression may be novel therapeutic strategies in OS.

The Heterogeneity of Osteosarcoma: The Role Played by Cancer Stem Cells

Osteosarcoma is the most common bone sarcoma and is one of the cancer entities characterized by the highest level of heterogeneity in humans. This heterogeneity takes place not only at the macroscopic and microscopic levels, with heterogeneous micro-environmental components, but also at the genomic, transcriptomic and epigenetic levels. Recent investigations have revealed the existence in osteosarcoma of cancer cells with stemness properties. Cancer stem cells are characterized by their specific phenotype and low cycling capacity, and are linked to drug resistance, tumour growth and the metastatic process. In addition, cancer stem cells contribute to the enrichment of tumour heterogeneity. The present manuscript will describe the main characteristic features of cancer stem cells in osteosarcoma and will discuss their impact on maintaining tumour heterogeneity. Their clinical implications will also be briefly addressed.

Osteoimmunology of Oral and Maxillofacial Diseases: Translational Applications Based on Biological Mechanisms

The maxillofacial skeleton is highly dynamic and requires a constant equilibrium between the bone resorption and bone formation. The field of osteoimmunology explores the interactions between bone metabolism and the immune response, providing a context to study the complex cellular and molecular networks involved in oro-maxillofacial osteolytic diseases. In this review, we present a framework for understanding the potential mechanisms underlying the immuno-pathobiology in etiologically-diverse diseases that affect the oral and maxillofacial region and share bone destruction as their common clinical outcome. These otherwise different pathologies share similar inflammatory pathways mediated by central cellular players, such as macrophages, T and B cells, that promote the differentiation and activation of osteoclasts, ineffective or insufficient bone apposition by osteoblasts, and the continuous production of osteoclastogenic signals by immune and local stromal cells. We also present the potential translational applications of this knowledge based on the biological mechanisms involved in the inflammation-induced bone destruction. Such applications can be the development of immune-based therapies that promote bone healing/regeneration, the identification of host-derived inflammatory/collagenolytic biomarkers as diagnostics tools, the assessment of links between oral and systemic diseases; and the characterization of genetic polymorphisms in immune or bone-related genes that will help diagnosis of susceptible individuals.

Knockdown of HOXB8 inhibits tumor growth and metastasis by the inactivation of Wnt/β-catenin signaling pathway in osteosarcoma

Homeobox B8 (HOXB8) is a member of HOX family and was reported to be dysregulated in human cancers. However, its expression pattern and function in human osteosarcoma (OS) remain unknown. The aim of the current study is to examine its expression and biological roles in human OS cells. Our results showed that HOXB8 was highly expressed in human OS tissues and cell lines. Knockdown of HOXB8 significantly suppressed the proliferation of OS cells in vitro and attenuated the tumor growth in a tumor xenograft model. In addition, knockdown of HOXB8 dramatically repressed the migration and invasion of OS cells. Furthermore, knockdown of HOXB8 efficiently prevented the activation of Wnt/β-catenin signaling pathway in OS cells. In conclusion, the findings of the present study demonstrated that knockdown of HOXB8 could suppress tumorigenesis and metastasis in OS through regulation of the Wnt/β-catenin signaling pathway. Thus, HOXB8 may represent a novel therapeutic target for the treatment of OS.

Allogenic γδ T cell and tumor cell fused vaccine for enhanced immunotherapeutic efficacy of osteosarcoma

Human γδ T cells have displayed their potential in cancer immunity through efficient tumor killing activities. Besides, they are also known for their capacity of antigen presentation. How to improve γδ T cells' immunotherapeutic effect as the cell vaccine is still a great challenge. Herein, we explore the human γδ T cells and tumor cell fused vaccine for enhanced immunotherapeutic efficacy of osteosarcoma. The fusion cell vaccine was prepared by chemical fusion between human γδ T cells and inactive osteosarcoma Saos-2 cells. The fusion process was confirmed by microscopy observation, and flow cytometry analysis further validated the antigen presenting functions of the fusion cells. Moreover, the immunotherapeutic potential of the fusion cells was then verified via cytotoxicity assay and cytokine release detection. Our study provided novel immunotherapeutic strategy for patients with osteosarcoma, which merits further practice in the near future.

The Intrinsic and Extrinsic Implications of RANKL/RANK Signaling in Osteosarcoma: From Tumor Initiation to Lung Metastases

Background: Osteosarcoma is the most frequent form of malignant pediatric bone tumor. Despite the current therapeutic arsenal, patient life-expectancy remains low if metastases are detected at the time of diagnosis, justifying research into better knowledge at all stages of osteosarcoma ontogenesis and identification of new therapeutic targets. Receptor Activator of Nuclear factor κB (RANK)expression has been reported in osteosarcoma cells, raising the question of Receptor Activator of Nuclear factor κB Ligand (RANKL)/RANK signaling implications in these tumor cells (intrinsic), in addition to previously reported implications through osteoclast activation in the tumor microenvironment (extrinsic). Methods: Based on in vitro and in vivo experimentations using human and mouse osteosarcoma cell lines, the consequences on the main cellular processes of RANK expression in osteosarcoma cells were analyzed. Results: The results revealed that RANK expression had no impact on cell proliferation and tumor growth, but stimulated cellular differentiation and, in an immune-compromised environment, increased the number of lung metastases. The analysis of RANKL, RANK and osteoprotegerin (OPG) expressions in biopsies of a cohort of patients revealed that while RANK expression in osteosarcoma cells was not significantly different between patients with or without metastases at the time of diagnosis, the OPG/RANK ratio decreased significantly. Conclusion: Altogether, these results are in favor of RANKL-RANK signaling inhibition as an adjuvant for the treatment of osteosarcoma.

Progress in the chemotherapeutic treatment of osteosarcoma

Osteosarcoma (OS) is the most common type of primary bone tumor in children and adolescents and has been associated with a high degree of malignancy, early metastasis, rapid progression and poor prognosis. However, the use of adjuvant chemotherapy improves the prognosis of patients with OS. OS chemotherapy is based primarily on the use of adriamycin, cisplatin (DDP), methotrexate (MTX), ifosfamide (IFO), epirubicin (EPI) and other drugs. Previous studies have revealed that the survival rate for patients with OS appears to have plateaued: 5-year survival rates remain close to 60%, even with the use of combined chemotherapy. The most limiting factors include complications and fatal toxicity associated with chemotherapy agents, particularly high-dose MTX (HD-MTX), for which high toxicity and great individual variation in responses have been observed. Docetaxel (TXT) is a representative member of the relatively recently developed taxane class of drugs, which function to inhibit OS cell proliferation and induce apoptosis. Recently, more clinical studies have reported that TXT combined with gemcitabine (GEM) is effective in the treatment of OS (relapse/refractory and progressive), providing evidence in support of potential novel treatment strategies for this patient population. However, there is still no global consensus on this type of chemotherapy approach. The present review summarizes current studies surrounding progress in the chemotherapeutic treatment of OS and discusses the advantages and potential feasibility of TXT+GEM in the treatment of OS.

Isolation of circulating tumor cells in a preclinical model of osteosarcoma: Effect of chemotherapy

Osteosarcoma is a rare primary bone tumor, which mainly affects children and adolescents and has a poor prognosis, especially for patients with metastatic disease. A poor therapeutic response to the conventional chemotherapy is observed with the development of lung metastases, highlighting the need for improving the current regimens and the identification of early markers of the recurrent and metastatic disease. Circulating Tumour Cells (CTCs) play a key role in the metastatic process and could be powerful biomarkers of the progressive disease. The present study aimed to isolate CTCs by using a pre-clinical model of human osteosarcoma and to monitor their kinetic of release and their modulation by ifosfamide. CTCs were detectable into the bloodstream before any palpable primary tumors. Ifosfamide increased CTCs count and in contrast decreased the number of lung tumor nodules. On established tumors, ifosfamide slowed down the tumour growth and did not modulate CTC count that could be explained by a release of cancer cells from the primary tumour with reduced properties for inducing lung metastases. This report highlights the biological interest of CTCs in osteosarcoma.

Oral administration of edelfosine encapsulated lipid nanoparticles causes regression of lung metastases in pre-clinical models of osteosarcoma

Osteosarcoma (OS) is the most frequent paediatric bone cancer, responsible for 9% of all cancer-related deaths in children. In this paper, a new strategy based on delivering edelfosine (ET) in lipid nanoparticles (LN) was explored in order to target the primary tumour and eliminate metastases. The in vitro and in vivo efficacy of the free drug, drug loaded into lipid nanoparticles (ET-LN) and doxorubicin (DOX) against osteosarcoma (OS) cells was analysed. ET and ET-LN decreased the growth of OS cells in vitro in a time- and dose-dependent manner. Interestingly, the uptake of ET and ET-LN was lower when OS cells were pre-treated with DOX. In vivo studies revealed that ET and ET-LN slowed down the primary tumour growth in two OS models. However, the combination of both drugs showed no additional anti-tumour effect. Importantly, ET-LN successfully prevented the metastatic spread of OS cells from the primary tumour to the lungs. On the whole, ET-LN are a promising candidate for OS chemotherapy.

Ginsenoside Rg3 Suppresses Proliferation and Induces Apoptosis in Human Osteosarcoma

Osteosarcoma is the most common primary malignancy of bone in children and the elderly. Recently, more and more researches have demonstrated that Ginsenoside Rg3 (Rg3) is involved in chemotherapy resistance in many cancer, making it a promising Chinese herbal monomer for oncotherapy. In this study, we investigated the efficacy of Rg3 in human osteosarcoma cell lines (MG-63, U-2OS, and SaOS-2). Cell proliferation was measured by CCK8 assay. The migration of cells was examined using the scratch assay method. Quantification of apoptosis was assessed further by flow cytometry. In addition, the expression of apoptosis-related genes (caspase9, caspase3, Bcl2, and Bax) were investigated using RT-PCR. We further investigated the protein level expression of Bcl 2, cleaved-caspase3, and PI3K/AKT/mTOR signaling pathway factors by Western blot assay. Our results revealed that Rg3 inhibited the proliferation and migration of human osteosarcoma cells and induced apoptosis in a concentration- and time-dependent manner. Western blot results showed that Rg3 reduced the protein expression of Bcl2 and PI3K/AKT/mTORbut increased the levels of cleaved-caspase3. Therefore, we hypothesized Rg3 inhibits the proliferation of osteosarcoma cell line and induces their apoptosis by affecting apoptosis-related genes (Bcl2, caspase3) as well as the PI3K/AKT/mTOR signaling pathway. To conclude, Rg3 is a new therapeutic agent against osteosarcoma.

Dysregulation of macrophage polarization is associated with the metastatic process in osteosarcoma

Osteosarcoma (OS) is the most common bone sarcoma in adolescents, and has poor prognosis. A vicious cycle is established between OS cells and their microenvironment in order to facilitate the tumor growth and cell spreading. The present work aims to better characterize the tumor microenvironment in OS in order to identify new therapeutic targets relating to metastatic process. Tissue microarrays of pre-chemotherapy OS biopsies were used for characterizing the tumor niche by immunohistochemistry. Parameters studies included: immune cells (M1, M2-subtypes of tumor-associated macrophages (TAM); T, B lymphocytes; mast cells), vascularization (endothelial, perivascular cells), OPG, RANKL, and mitotic index. Two groups of patients were defined, 22 localized OS (OS Meta-) and 28 metastatic OS (OS Meta+). The OS Meta- group was characterized by a higher infiltration of INOS+ M1-polarizedmacrophages and upregulated OPG immunostaining. OS Meta+ tumors showed a significant increase in CD146+ cells. INOS+ M1-macrophages were correlated with OPG staining, and negatively with the presence of metastases. CD163+ M2-macrophages were positively correlated with CD146+ cells. In multivariate analysis, INOS and OPG were predictive factors for metastasis. An older age, non-metastatic tumor, good response to chemotherapy, and higher macrophage infiltration were significantly associated with better overall survival. TAMs are associated with better overall survival and a dysregulation of M1/M2 polarized-macrophages in favor of M1 subtype was observed in non-metastatic OS.

Expression patterns of class I histone deacetylases in osteosarcoma: a novel prognostic marker with potential therapeutic implications

Epigenetic aberrations are recognized as having pivotal roles in cancer etiology and progression. Histone deacetylases are among the most studied epigenetic modulators in various cancer types. The expression levels of class I histone deacetylase isoforms 1, 2, and 3 in patient-derived primary osteosarcoma cells (6 cases) was investigated, comparing them to normal bone graft-derived osteoblasts (6 cases) using the immunoblotting technique. Expression profiles of histone deacetylases in high-grade osteosarcoma tissue of 89 patients were examined and their association with clinicopathologic parameters and the patient survival was evaluated. Histone deacetylases were immunohistochemically stained on formalin-fixed paraffin-embedded biopsied tissue. Primary osteosarcoma cells expressed higher levels of histone deacetylase 1 and histone deacetylase 2, but lower levels of histone deacetylase 3 compared to benign osteoblasts. Overall, 82, 99, and 93% of 89 osteosarcomas showed nuclear expression of the histone deacetylase isoforms 1, 2, and 3, respectively. Low levels of histone deacetylase 1 were significantly associated with a high Enneking stage (P=0.014) and the presence of initial metastasis (P=0.040), while low levels of histone deacetylase 3 were significantly correlated with age >15 years (P=0.026). Univariate survival analysis found significantly shorter survival in the patients with a high Enneking stage (P<0.001), axial location (P=0.009), presence of initial metastasis (P<0.001), low-histone deacetylase 1 expression (P=0.038), and low-all-histone deacetylases expression (P=0.016). Multivariate survival analysis showed that only axial location (P=0.011) and low-all-histone deacetylases expression (P=0.039) were independent prognostic factors. In subgroup analysis of stage IIB patients (n=45), only axial location and low-all-histone deacetylases expression were associated with shorter survival in both univariate and multivariate analysis (axial location, P=0.008 and 0.010; low-all-HDACs, P=0.013 and 0.038, respectively). Low levels of all-histone deacetylases expression were significantly associated with advanced disease status and short survival. These findings may be a guide to future use of histone deacetylase inhibitors in osteosarcoma patients.

Biology of Bone Sarcomas and New Therapeutic Developments

Bone sarcomas are tumours belonging to the family of mesenchymal tumours and constitute a highly heterogeneous tumour group. The three main bone sarcomas are osteosarcoma, Ewing sarcoma and chondrosarcoma each subdivided in diverse histological entities. They are clinically characterised by a relatively high morbidity and mortality, especially in children and adolescents. Although these tumours are histologically, molecularly and genetically heterogeneous, they share a common involvement of the local microenvironment in their pathogenesis. This review gives a brief overview of their specificities and summarises the main therapeutic advances in the field of bone sarcoma.

Pediatric Cancer Immunotherapy: Opportunities and Challenges

Cancer immunotherapies, widely heralded as transformational for many adult cancer patients, are becoming viable options for selected subsets of pediatric cancer patients. Many therapies are currently being investigated, from immunomodulatory agents to adoptive cell therapy, bispecific T-cell engagers, oncolytic virotherapy, and checkpoint inhibition. One of the most exciting immunotherapies recently FDA approved is the use of CD19 chimeric antigen receptor T cells for pre-B-cell acute lymphoblastic leukemia. With this approval and others, immunotherapy for pediatric cancers is gaining traction. One of the caveats to many of these immunotherapies is the challenge of predictive biomarkers; determining which patients will respond to a given therapy is not yet possible. Much research is being focused on which biomarkers will be predictive and prognostic for these patients. Despite many benefits of immunotherapy, including less long-term side effects, some treatments are fraught with immediate side effects that range from mild to severe, although most are manageable. With few downsides and the potential for disease cures, immunotherapy in the pediatric population has the potential to move to the front-line of therapeutic options.

Long Noncoding RNA miR210HG Sponges miR-503 to Facilitate Osteosarcoma Cell Invasion and Metastasis

Long noncoding RNAs (lncRNAs) have been illustrated to function as important regulator in carcinogenesis and cancer progression. However, roles of lncRNA miR210HG (miR210 host gene) in osteosarcoma remain unclear. In this study, miR210HG expression level was significantly upregulated in 55 cases of osteosarcoma tissue samples compared to adjacent normal tissue. Besides, the aberrantly enhanced miR210HG expression predicted poor prognosis and lower survival rate. In vitro, miR210HG knockdown suppressed the osteosarcoma cell proliferation, invasion, and epithelial-mesenchymal transition-related marker (N-cadherin and vimentin) expression. In vivo, miR210HG silencing decreased the tumor growth. miR-503 was verified to be the target miRNA of miR210HG using bioinformatics online program and luciferase assay. Furthermore, miR-503 could reverse the role of miR210HG on osteosarcoma cells. In conclusion, our study indicates that miR210HG sponges miR-503 to facilitate osteosarcoma cell invasion and metastasis, revealing the oncogenic role of miR210HG on osteosarcoma cells.

Multitype Network-Guided Target Controllability in Phenotypically Characterized Osteosarcoma: Role of Tumor Microenvironment

This study highlights the relevance of network-guided controllability analysis as a precision oncology tool. Target controllability through networks is potentially relevant to cancer research for the identification of therapeutic targets. With reference to a recent study on multiple phenotypes from 22 osteosarcoma (OS) cell lines characterized both in vitro and in vivo, we found that a variety of critical proteins in OS regulation circuits were in part phenotype specific and in part shared. To generalize our inference approach and match cancer phenotypic heterogeneity, we employed multitype networks and identified targets in correspondence with protein sub-complexes. Therefore, we established the relevance for diagnostic and therapeutic purposes of inspecting interactive targets, namely those enriched by significant connectivity patterns in protein sub-complexes. Emerging targets appeared with reference to the OS microenvironment, and relatively to small leucine-rich proteoglycan members and D-type cyclins, among other collagen, laminin, and keratin proteins. These described were evidences shared across all phenotypes; instead, specific evidences were provided by critical proteins including IGFBP7 and PDGFRA in the invasive phenotype, and FGFR3 and THBS1 in the colony forming phenotype.