Osteosarcoma

Lenvatinib Plus Ifosfamide and Etoposide in Children and Young Adults With Relapsed Osteosarcoma: A Phase 2 Randomized Clinical Trial

Importance

The combination of ifosfamide and etoposide (IE) is commonly used to treat relapsed or refractory osteosarcoma; however, second-line treatment recommendations vary across guidelines.

Objective

To evaluate whether the addition of lenvatinib to IE (LEN-IE) improves outcomes in children and young adults with relapsed or refractory osteosarcoma.

Design, Setting, and Participants

The OLIE phase II, open-label, randomized clinical trial was conducted globally across Europe, Asia and the Pacific, and North America. From March 22, 2020, through November 11, 2021, the trial enrolled patients aged 2 to 25 years with high-grade osteosarcoma, measurable or evaluable disease per Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST 1.1), and 1 to 2 prior lines of systemic treatment. The data analyses were performed between March 22, 2020 (first patient in) and June 22, 2022 (data cutoff for the primary analysis), and September 29, 2023 (end of study final database lock).

Interventions

The OLIE trial assessed the efficacy and safety of lenvatinib (14 mg/m2 taken orally once daily) combined with up to 5 cycles of ifosfamide (3000 mg/m2 intravenously) and etoposide (100 mg/m2 intravenously) on days 1 to 3 of each cycle vs IE alone at the same doses. Patients randomized to IE could cross over to receive lenvatinib upon disease progression by independent imaging review.

Main Outcomes and Measures

The primary end point was progression-free survival (PFS) per RECIST 1.1 by independent imaging review. The Kaplan-Meier method was used to estimate the PFS distribution, with a prespecified 1-sided significance threshold of .025 by stratified log-rank test. Secondary end points included PFS rate at 4 months and overall survival. Adverse events were summarized using descriptive statistics.

Results

A total of 81 patients were enrolled (median [IQR] age, 15.0 [12.0-18.0] years; 46 males [56.8%]), with 40 in the LEN-IE arm and 41 in the IE arm. Median PFS was 6.5 months (95% CI, 5.7-8.2 months) for the LEN-IE arm and 5.5 months (95% CI, 2.9-6.5 months) for the IE arm (hazard ratio [HR], 0.54; 95% CI, 0.27-1.08; 1-sided P = .04). The rate of PFS at 4 months was 76.3% (95% CI, 59.3%-86.9%) in the LEN-IE arm and 66.0% (95% CI, 47.7%-79.2%) in the IE arm. Median overall survival was 11.9 months (95% CI, 10.1 months to not estimable) with LEN-IE and 17.4 months (95% CI, 14.2 months to not estimable) with IE (HR, 1.28; 95% CI, 0.60-2.70; 1-sided nominal P = .75). Grade 3 or higher treatment-related adverse events occurred in 35 of 39 patients (89.7%) in the LEN-IE arm and 31 of 39 patients (79.5%) in the IE arm.

Conclusions and Relevance

Although LEN-IE did not meet prespecified statistical significance for improved PFS vs IE, this study demonstrates the importance of international collaboration and randomized clinical trials in patients with relapsed or refractory osteosarcoma and may inform future trial design.

Trial Registration

ClinicalTrials.gov Identifier: NCT04154189.

Biomechanical Aspects in Bone Tumor Engineering

In the past decades, anticancer drug development brought the field of tumor engineering to a new level by the need of robust test systems. Simulating tumor microenvironment in vitro remains a challenge, and osteosarcoma-the most common primary bone cancer-is no exception. The growing evidence points to the inevitable connection between biomechanical stimuli and tumor chemosensitivity and aggressiveness, thus making this component of the microenvironment a mandatory requirement to the developed models. In this review, we addressed the question: is the "in vivo - in vitro" gap in osteosarcoma engineering bridged from the perspective of biomechanical stimuli? The most notable biomechanical cues in the tumor cell microenvironment are observed and compared in the contexts of in vivo conditions and engineered three-dimensional in vitro models. Impact statement The importance of biomechanical stimuli in three-dimensional in vitro models for drug testing is becoming more pronounced nowadays. This review might assist in understanding the key players of the biophysical environment of primary bone cancer and the current state of bone tumor engineering from this perspective.

Promising Dual Anticancer and Antimetastatic Action by a Cu(II) Complex Derived from Acylhydrazone on Human Osteosarcoma Models

Osteosarcoma cancers are becoming more common in children and young adults, and existing treatments have low efficacy and a very high mortality rate, making it pressing to search for new chemotherapies with high efficacy and high selectivity index. Copper complexes have shown promise in the treatment of osteosarcoma. Here, we report the synthesis, characterization, and anticancer activity of [Cu(N-N-Fur)(NO3)(H2O)] complex where N-N-Fur is (E)-N'-(2-hydroxy-3-methoxybenzylidene)furan-2-carbohydrazide. The [Cu(N-N-Fur)(NO3)(H2O)] complex was characterized via X-ray diffraction and electron spin resonance (ESR), displaying a copper center in a nearly squared pyramid environment with the nitrate ligand acting as a fifth ligand in the coordination sphere. We observed that [Cu(N-N-Fur)(NO3)(H2O)] binds to DNA in an intercalative manner. Anticancer activity on the MG-63 cell line was evaluated in osteosarcoma monolayer (IC50 2D: 1.1 ± 0.1 μM) and spheroids (IC50 3D: 16.3 ± 3.1 μM). Selectivity assays using nontumoral fibroblast (L929 cell line) showed that [Cu(N-N-Fur)(NO3)(H2O)] has selectivity index value of 2.3 compared to cis-diamminedichloroplatinum(II) (CDDP) (SI = 0.3). Additionally, flow cytometry studies demonstrated that [Cu(N-N-Fur)(NO3)(H2O)] inhibits cell proliferation and conveys cells to apoptosis. Cell viability studies of MG-63 spheroids (IC50 = 16.3 ± 3.1 μM) showed that its IC50 value is 4 times lower than for CDDP (IC50 = 65 ± 6 μM). Besides, we found that cell death events mainly occurred in the center region of the spheroids, indicating efficient transport to the microtumor. Lastly, the complex showed dose-dependent reductions in spheroid cell migration from 7.5 to 20 μM, indicating both anticancer and antimetastatic effects.

WWOX promotes osteosarcoma development via upregulation of Myc

Osteosarcoma is an aggressive bone tumor that primarily affects children and adolescents. This malignancy is highly aggressive, associated with poor clinical outcomes, and primarily metastasizes to the lungs. Due to its rarity and biological heterogeneity, limited studies on its molecular basis exist, hindering the development of effective therapies. The WW domain-containing oxidoreductase (WWOX) is frequently altered in human osteosarcoma. Combined deletion of Wwox and Trp53 using Osterix1-Cre transgenic mice has been shown to accelerate osteosarcoma development. In this study, we generated a traceable osteosarcoma mouse model harboring the deletion of Trp53 alone (single-knockout) or combined deletion of Wwox/Trp53 (double-knockout) and expressing a tdTomato reporter. By tracking Tomato expression at different time points, we detected the early presence of tdTomato-positive cells in the bone marrow mesenchymal stem cells of non-osteosarcoma-bearing mice (young BM). We found that double-knockout young BM cells, but not single-knockout young BM cells, exhibited tumorigenic traits both in vitro and in vivo. Molecular and cellular characterization of these double-knockout young BM cells revealed their resemblance to osteosarcoma tumor cells. Interestingly, one of the observed significant transcriptomic changes in double-knockout young BM cells was the upregulation of Myc and its target genes compared to single-knockout young BM cells. Intriguingly, Myc-chromatin immunoprecipitation sequencing revealed its increased enrichment on Myc targets, which were upregulated in double-knockout young BM cells. Restoration of WWOX in double-knockout young BM cells reduced Myc protein levels. As a prototype target, we demonstrated the upregulation of MCM7, a known Myc target, in double-knockout young BM relative to single-knockout young BM cells. Inhibition of MCM7 expression using simvastatin resulted in reduced proliferation and tumor cell growth of double-knockout young BM cells. Our findings reveal BM mesenchymal stem cells as a platform to study osteosarcoma and Myc and its targets as WWOX effectors and early molecular events during osteosarcomagenesis.

Silencing FUT4 Inhibits the Progression of Osteosarcoma through Activation of FOXO1

BACKGROUND

It has been reported that inhibition of Fucosyltransferase4 (FUT4) to activate Forkhead box O1 (FOXO1) can lead to apoptosis of cancer cells, however, the mechanism in osteosarcoma is still unclear.

OBJECTIVE

To explore the biological significance of the connection between FUT4 and FOXO1 in osteosarcoma growth.

METHODS

In vitro tests were conducted using the human osteoblast cell line and the osteosarcoma cell lines. QRT-PCR assay as well as western blot assay were used to ascertain the relative expression levels of FUT4 and FOXO1 in the cells. By using the CCK-8 assay, colony assay, EDU assay, wound healing assay and Transwell assay, osteosarcoma cells' ability to proliferate, migrate and invade were examined in relation to si- FUT4. TUNEL test was used to evaluate Si-impact FUT4's on KHOS and U2OS apoptosis in osteosarcoma cells. Western blot assay was used to identify the expression of proliferative, migrating and apoptosis-related protein markers in osteosarcoma cells KHOS and U2OS and the expression of important proteins in the Wnt/ β-catenin signaling pathway.

RESULTS

In comparison with osteoblasts, osteosarcoma cells expressed more FUT4. The osteosarcoma cells' capacities to proliferate, invade, and migrate were markedly inhibited by the inhibition of FUT4 expression, which also increased osteosarcoma cell apoptosis. The Wnt/β-catenin signaling pathway was blocked by upregulating FOXO1 expression, which was in turn inhibited by inhibiting FUT4 expression.

CONCLUSION

Osteosarcoma cells express more FUT4. The Wnt/β-catenin signaling pathway has a significant effect on osteosarcoma cell death, and inhibition of FUT4 expression may target FOXO1 activation to decrease osteosarcoma cells' ability to proliferate, invade, and migrate.

Rehabilitation Following Above-Knee Amputation in a Pediatric Osteosarcoma Patient: A Case Report

The earliest stages of osteosarcomas are primitive mesenchymal cells. It generally occurs close to the long bones' metaphysis and typically affects the long bones, such as the arm and leg. This case report underscores the pivotal role of physiotherapy in the rehabilitation of a 14-year-old male diagnosed with osteosarcoma, who underwent above-knee amputation. The structured six-week rehabilitation program, encompassing passive, active-assisted, and active exercises for the affected limb, alongside strength training for unaffected joints, produced notable gains in the pain rating scale and the lower-extremity functional scale in just 15 days. These outcomes underscore the significance of early and targeted physiotherapy interventions in optimizing functional outcomes and quality of life for young patients with osteosarcoma after surgery.

Cu(II)-acylhydrazone complex, a potent and selective antitumor agent against human osteosarcoma: Mechanism of action studies over in vitro and in vivo models

Osteosarcoma (OS) is a frequent bone cancer, affecting largely children and young adults. Cisplatin (CDDP) has been efficacious in the treatment of different cancer such us OS but the development of chemoresistance and important side effects leading to therapeutic failure. Novel therapies including copper compounds have shown to be potentially effective as anticancer drugs and one alternative to usually employed platinum compounds. The goal of this work is the evaluation of the in vitro and in vivo antitumoral activity and dilucidate the molecular target of a Cu(II) cationic complex containing a tridentate hydrazone ligand, CuHL for short, H2L=N'-'-(2-hydroxy-3-methoxybenzylidene)thiophene-2-carbohydrazide, against human OS MG-63 cells. Anticancer activity on MG-63 cell line was evaluated in OS monolayer and spheroids. CuHL significantly impaired cell viability in both models (IC50 2D: 2.1 ± 0.3 μM; 3D: 9.1 ± 1.0 μM) (p < 0.001). Additional cell studies demonstrated the copper compound inhibits cell proliferation and conveys cells to apoptosis, determined by flow cytometry. CuHL showed a great genotoxicity, evaluated by comet assay. Proteomic analysis by Orbitrap Mass Spectometry identified 27 differentially expressed proteins: 17 proteins were found overexpressed and 10 underexpressed in MG-63 cells after the CuHL treatment. The response to unfolded protein was the most affected biological process. In addition, in vivo antitumor effects of the compound were evaluated on human OS tumors xenografted in nude mice. CuHL treatment, at a dose of 2 mg/kg i.p., given three times/week for one month, significantly inhibited the progression of OS xenografts and was associated to a reduction in mitotic index and to an increment of tumor necrosis (p < 0.01). Administration of standard-of-care cytotoxic agent CDDP, following the same treatment schedule as CuHL, failed to impair OS growth and progression.

Bioinspired Tumor-Targeting and Biomarker-Activatable Cell-Material Interfacing System Enhances Osteosarcoma Treatment via Biomineralization

Osteosarcoma is an aggressive malignant tumor that primarily develops in children and adolescents. The conventional treatments for osteosarcoma often exert negative effects on normal cells, and chemotherapeutic drugs, such as platinum, can lead to multidrug resistance in tumor cells. Herein, this work reports a new bioinspired tumor-targeting and enzyme-activatable cell-material interface system based on DDDEEK-pY-phenylboronic acid (SAP-pY-PBA) conjugates. Using this tandem-activation system, this work selectively regulates the alkaline phosphatase (ALP) triggered anchoring and aggregation of SAP-pY-PBA conjugates on the cancer cell surface and the subsequent formation of the supramolecular hydrogel. This hydrogel layer can efficiently kill osteosarcoma cells by enriching calcium ions from tumor cells and forming a dense hydroxyapatite layer. Owing to the novel antitumor mechanism, this strategy neither hurts normal cells nor causes multidrug resistance in tumor cells, thereby showing an enhanced tumor treatment effect than the classical antitumor drug, doxorubicin (DOX). The outcome of this research demonstrates a new antitumor strategy based on a bioinspired enzyme-responsive biointerface combining supramolecular hydrogels with biomineralization.

Differential diagnosis of an osseous cranial tumor from Hellenistic Muğla, Turkey

OBJECTIVE

This project evaluates a cranial lesion from a Hellenistic-era individual excavated by the Muğla Archaeological Museum in Gülağzı, Turkey.

MATERIALS

An osseous tumor measuring 3.02 × 3.54 × 2.98 cm originating from the occipital bone of a probable young adult male.

METHODS

The tumor was examined using gross morphological inspection, plain radiography (x-ray), and computed tomography (CT) imaging to identify potential differential diagnoses for the osseous cranial tumor.

RESULTS

The lesion in question displays features highly consistent with both osteoid osteoma and osteoblastoma. The tumor had a non-sclerotic, sharply demarcated border, a radiolucent nidus measuring less than 2 centimeters in diameter, and homogeneous sclerotic bone surrounding the nidus.

CONCLUSIONS

Differential diagnosis determined the osseous tumor to be a benign neoplasm, and in this case the features of the tumor are highly consistent with a diagnosis of either osteoblastoma or osteoid osteoma.

SIGNIFICANCE

The identification of novel neoplastic cases in paleopathology represents an important contribution to ongoing discussions regarding the temporality and regional variability of neoplastic conditions in the past. Additionally, a rigorous diagnostic study augmented by x-ray, CT scans, and 3D modeling provides data that can be utilized in future paleopathological studies.

LIMITATIONS

Diagnostic interpretation would be aided by histological examination of the tumor, which was impossible in this case. Histological examination would provide a definitive diagnosis.

SUGGESTIONS FOR FURTHER RESEARCH

Given the high incidence of benign tumors in the clinical literature but a paucity of reports in the paleopathological record, further research is indicated to better understand the implications of benign neoplasms in antiquity.

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.

Single-cell RNA sequencing reveals differential expression of EGFL7 and VEGF in giant-cell tumor of bone and osteosarcoma

Dysregulation of angiogenesis is associated with tumor development and is accompanied by altered expression of pro-angiogenic factors. EGFL7 is a newly identified antigenic factor that plays a role in various cancers such as breast cancer, lung cancer, and acute myeloid leukemia. We have recently found that EGFL7 is expressed in the bone microenvironment, but its role in giant-cell tumor of bone (GCTB) and osteosarcoma (OS) is unknown. The aims of this study are to examine the gene expression profile of EGFL7 in GCTB and OS and compare with that of VEGF-A-D and TNFSF11 using single-cell RNA sequencing data. In-depth differential expression analyses were employed to characterize their expression in the constituent cell types of GCTB and OS. Notably, EGFL7 in GCTB was expressed at highest levels in the endothelial cell (EC) cluster followed by osteoblasts, myeloid cells, and chondrocytes, respectively. In OS, EGFL7 exhibited highest expression in EC cell cluster followed by osteoblastic OS cells, myeloid cells 1, and carcinoma associated fibroblasts (CAFs), respectively. In comparison, VEGF-A is expressed at highest levels in myeloid cells followed by OCs in GCTB, and in myeloid cells, and OCs in OS. VEGF-B is expressed at highest levels in chondrocytes in GCTB and in OCs in OS. VEGF-C is strongly enriched in ECs and VEGF-D is expressed at weak levels in all cell types in both GCTB and OS. TNFSF11 (or RANKL) shows high expression in CAFs and osteoblastic OS cells in OS, and osteoblasts in GCTB. This study investigates pro-angiogenic genes in GCTB and OS and suggests that these genes and their expression patterns are cell-type specific and could provide potential prognostic biomarkers and cell type target treatment for GCTB and OS.

Tetraspanin 7 promotes osteosarcoma cell invasion and metastasis by inducing EMT and activating the FAK-Src-Ras-ERK1/2 signaling pathway

Background

Tetraspanins are members of the 4-transmembrane protein superfamily (TM4SF) that function by recruiting many cell surface receptors and signaling proteins into tetraspanin-enriched microdomains (TEMs) that play vital roles in the regulation of key cellular processes including adhesion, motility, and proliferation. Tetraspanin7 (Tspan7) is a member of this superfamily that plays documented roles in hippocampal neurogenesis, synaptic transmission, and malignant transformation in certain tumor types. How Tspan7 influences the onset or progression of osteosarcoma (OS), however, remains to be defined. Herein, this study aimed to explore the relationship between Tspan7 and the malignant progression of OS, and its underlying mechanism of action.

Methods

In this study, the levels of Tspan7 expression in human OS cell lines were evaluated via qRT-PCR and western blotting. The effect of Tspan7 on proliferation was examined using CCK-8 and colony formation assays, while metastatic role of Tspan7 was assessed by functional assays both in vitro and in vivo. In addition, mass spectrometry and co-immunoprecipitation were performed to verify the interaction between Tspan7 and β1 integrin, and western blotting was used to explore the mechanisms of Tspan7 in OS progresses.

Results

We found that Tspan7 is highly expressed in primary OS tumors and OS cell lines. Downregulation of Tspan7 significantly suppressed OS growth, metastasis, and attenuated epithelial-mesenchymal transition (EMT), while its overexpression had the opposite effects in vitro. Furthermore, it exhibited reduced OS pulmonary metastases in Tspan7-deleted mice comparing control mice in vivo. Additionally, we proved that Tspan7 interacted with β1 integrin to facilitate OS metastasis through the activation of integrin-mediated downstream FAK-Src-Ras-ERK1/2 signaling pathway.

Conclusion

In summary, this study demonstrates for the first time that Tspan7 promotes OS metastasis via interacting with β1 integrin and activating the FAK-Src-Ras-ERK1/2 pathway, which could provide rationale for a new therapeutic strategy for OS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02591-1.

Potential Seeding From Fine-Needle Aspiration of an Axial Osteosarcoma: A Case Report

This report describes the first potential case of seeding after fine-needle aspiration (FNA) of a rib osteosarcoma in a dog. An 8-year-old, 28-kg female spayed Golden Retriever was presented to her primary veterinarian with a 3-week history of a 3-cm firm, unpainful, immobile mass arising from the 9th rib. The mass was aspirated and submitted for cytological examination. A subcutaneous nodule developed several days after the FNA was performed in a location immediately overlying but distinct from the primary rib tumor on palpation. Both the primary mass and the newly diagnosed subcutaneous nodule were biopsied and were consistent with an osteosarcoma. Although it cannot be ruled out that the subcutaneous lesion was metastatic, seeding was a reasonable explanation based on where the new mass was located and how quickly it appeared after the FNA was performed. The aim of this case report was to describe the possibility of tumor seeding during FNA for osteosarcoma. It is the authors' opinion that utility of cytological diagnosis of bone tumors outweighs the risk of possible seeding and should continue to be used as a routine diagnostic test for the diagnosis of aggressive bone lesions.

Transcriptomic Analysis of Canine Osteosarcoma from a Precision Medicine Perspective Reveals Limitations of Differential Gene Expression Studies

Despite significant advances in cancer diagnosis and treatment, osteosarcoma (OSA), an aggressive primary bone tumor, has eluded attempts at improving patient survival for many decades. The difficulty in managing OSA lies in its extreme genetic complexity, drug resistance, and heterogeneity, making it improbable that a single-target treatment would be beneficial for the majority of affected individuals. Precision medicine seeks to fill this gap by addressing the intra- and inter-tumoral heterogeneity to improve patient outcome and survival. The characterization of differentially expressed genes (DEGs) unique to the tumor provides insight into the phenotype and can be useful for informing appropriate therapies as well as the development of novel treatments. Traditional DEG analysis combines patient data to derive statistically inferred genes that are dysregulated in the group; however, the results from this approach are not necessarily consistent across individual patients, thus contradicting the basis of precision medicine. Spontaneously occurring OSA in the dog shares remarkably similar clinical, histological, and molecular characteristics to the human disease and therefore serves as an excellent model. In this study, we use transcriptomic sequencing of RNA isolated from primary OSA tumor and patient-matched normal bone from seven dogs prior to chemotherapy to identify DEGs in the group. We then evaluate the universality of these changes in transcript levels across patients to identify DEGs at the individual level. These results can be useful for reframing our perspective of transcriptomic analysis from a precision medicine perspective by identifying variations in DEGs among individuals.

Potential anticancer properties and mechanisms of thymoquinone in osteosarcoma and bone metastasis

Despite great advances, therapeutic approaches of osteosarcoma, the most prevalent class of preliminary pediatric bone tumors, as well as bone-related malignancies, continue to demonstrate insufficient adequacy. In recent years, a growing trend toward applying natural bioactive compounds, particularly phytochemicals, as novel agents for cancer treatment has been observed. Bioactive phytochemicals exert their anticancer features through two main ways: they induce cytotoxic effects against cancerous cells without having any detrimental impact on normal cell macromolecules such as DNA and enzymes, while at the same time combating the oncogenic signaling axis activated in tumor cells. Thymoquinone (TQ), the most abundant bioactive compound of Nigella sativa, has received considerable attention in cancer treatment owing to its distinctive properties, including apoptosis induction, cell cycle arrest, angiogenesis and metastasis inhibition, and reactive oxygen species (ROS) generation, along with inducing immune system responses and reducing side effects of traditional chemotherapeutic drugs. The present review is focused on the characteristics and mechanisms by which TQ exerts its cytotoxic effects on bone malignancies.

MicroRNA-886 suppresses osteosarcoma cell proliferation and its maturation is suppressed by long non-coding RNA OXCT1-AS1

This study aimed to investigate the roles of microRNA-886 (miR-886) and long non-coding RNA (lncRNA) OXCT1-AS1 in osteosarcoma (OS). We predicted that they might interact with each other. The expression of OXCT1-AS1 and miR-886 (mature and premature) in osteosarcoma and paired non-tumor tissues from 66 OS patients was negatively correlated. Overexpression and silencing assays showed that OXCT1-AS1 suppresses miR-886 maturation. RNA-RNA pulldown and subcellular fractionation assays demonstrated the direct interaction between OXCT1-AS1 and miR-886. BrdU proliferation assays revealed that OXCT1-AS1 promoted OS cell proliferation, and miR-886 reduced the enhancing effects of OXCT1-AS1 on OS cell proliferation. Western blot showed that OXCT1-AS1 had no effects on the levels of epithelial-mesenchymal transition biomarkers. Overall, OXCT1-AS1 suppresses miR-886 maturation to promote OS cell proliferation.

Circle RNA circCSPP1 promotes human osteosarcoma cell proliferation and increases glucose metabolism by suppressing miR-200c maturation

INTRODUCTION

MiR-200c plays a central role in glucose metabolism in cancer cells. However, its upstream regulators in this process are unknown. CircRNA CSPP1 (circCSPP1) was predicted to bind to premature miR-200c, an oncogenic miRNA. Therefore, we explored their interaction in osteosarcoma (OS).

METHODS

Differential circCSPP1 and miR-200c expression in OS was analyzed using RT-qPCR. Glucose metabolism was analyzed by glucose uptake assay. Subcellular circCSPP1 location in OS cells was detected using cellular fractionation assay. The direct interaction between circCSPP1 and miR-200c was explored using RNA-RNA pull-down assay. The role of circCSPP1 in miR-200c maturation was investigated by analyzing both mature and premature miR-200c levels in OS cells with circCSPP1 overexpression.

RESULTS

CircCSPP1 and premature miR-200c levels were increased while mature miR-200c level was decreased in OS. CircCSPP1 was detected in both the nuclear and cytoplasm fractions of OS cells. CircCSPP1 directly interacted with premature miR-200c. CircCSPP1 overexpression increased premature miR-200c level, glucose uptake, and cell proliferation, but decreased mature miR-200c level. MiR-200c overexpression suppressed the role of circCSPP1 in OS cells.

CONCLUSIONS

CircCSPP1 promotes OS cell proliferation and increases glucose metabolism by suppressing miR-200c maturation.

Histotripsy Ablation in Preclinical Animal Models of Cancer and Spontaneous Tumors in Veterinary Patients: A Review

New therapeutic strategies are direly needed in the fight against cancer. Over the last decade, several tumor ablation strategies have emerged as stand-alone or combination therapies. Histotripsy is the first completely noninvasive, nonthermal, and nonionizing tumor ablation method. Histotripsy can produce consistent and rapid ablations, even near critical structures. Additional benefits include real-time image guidance, high precision, and the ability to treat tumors of any predetermined size and shape. Unfortunately, the lack of clinically and physiologically relevant preclinical cancer models is often a significant limitation with all focal tumor ablation strategies. The majority of studies testing histotripsy for cancer treatment have focused on small animal models, which have been critical in moving this field forward and will continue to be essential for providing mechanistic insight. While these small animal models have notable translational value, there are significant limitations in terms of scale and anatomical relevance. To address these limitations, a diverse range of large animal models and spontaneous tumor studies in veterinary patients have emerged to complement existing rodent models. These models and veterinary patients are excellent at providing realistic avenues for developing and testing histotripsy devices and techniques designed for future use in human patients. Here, we provide a review of animal models used in preclinical histotripsy studies and compare histotripsy ablation in these models using a series of original case reports across a broad spectrum of preclinical animal models and spontaneous tumors in veterinary patients.

Emerging role and function of miR-198 in human health and diseases

Ever since their discovery, microRNAs (miRNAs/miRs) have astonished us by the plethora of processes they regulate, and thus adding another dimension to the gene regulation. They have been implicated in several diseases affecting cardiovascular, neurodegenerative, hepatic, autoimmune and inflammatory functions. A primate specific exonic miRNA, miR-198 has been vastly studied during the past decade, and shown to have a critical role in wound healing. The aberrant expression of miR-198 was first reported in schizophrenia, linking it to neural development. Later, its dysregulation and tumor suppressive role was reported in hepatocellular carcinoma. However, this was just a beginning, and after which there was an explosion of reports linking miR-198 deregulation to cancers and other ailments. The first target to be identified for miR-198 was Cyclin T1 in monocytes affecting HIV1 replication. Depending on the type of cancer, miR-198 has been shown to function either as a tumor suppressor or an oncomir. Interestingly, miR-198 is not only known to regulate multiple targets and pathways, but also is itself regulated by several circular RNAs and long-non-coding RNAs, highlighting a complex regulatory network. This review highlights the currently understood mechanism and regulation of miR-198 in different diseases, and its possible diagnostic and therapeutic potential.

Therapeutic vulnerability to PARP1,2 inhibition in RB1-mutant osteosarcoma

Loss-of-function mutations in the RB1 tumour suppressor are key drivers in cancer, including osteosarcoma. RB1 loss-of-function compromises genome-maintenance and hence could yield vulnerability to therapeutics targeting such processes. Here we demonstrate selective hypersensitivity to clinically-approved inhibitors of Poly-ADP-Polymerase1,2 inhibitors (PARPi) in RB1-defective cancer cells, including an extended panel of osteosarcoma-derived lines. PARPi treatment results in extensive cell death in RB1-defective backgrounds and prolongs survival of mice carrying human RB1-defective osteosarcoma grafts. PARPi sensitivity is not associated with canonical homologous recombination defect (HRd) signatures that predict PARPi sensitivity in cancers with BRCA1,2 loss, but is accompanied by rapid activation of DNA replication checkpoint signalling, and active DNA replication is a prerequisite for sensitivity. Importantly, sensitivity in backgrounds with natural or engineered RB1 loss surpasses that seen in BRCA-mutated backgrounds where PARPi have established clinical benefit. Our work provides evidence that PARPi sensitivity extends beyond cancers identifiable by HRd and advocates PARP1,2 inhibition as a personalised strategy for RB1-mutated osteosarcoma and other cancers.

Avenues of research in dietary interventions to target tumor metabolism in osteosarcoma

Osteosarcoma (OS) is the most frequent primary bone cancer, affecting mostly children and adolescents. Although much progress has been made throughout the years towards treating primary OS, the 5-year survival rate for metastatic OS has remained at only 20% for the last 30 years. Therefore, more efficient treatments are needed. Recent studies have shown that tumor metabolism displays a unique behavior, and plays important roles in tumor growth and metastasis, making it an attractive potential target for novel therapies. While normal cells typically fuel the oxidative phosphorylation (OXPHOS) pathway with the products of glycolysis, cancer cells acquire a plastic metabolism, uncoupling these two pathways. This allows them to obtain building blocks for proliferation from glycolytic intermediates and ATP from OXPHOS. One way to target the metabolism of cancer cells is through dietary interventions. However, while some diets have shown anticancer effects against certain tumor types in preclinical studies, as of yet none have been tested to treat OS. Here we review the features of tumor metabolism, in general and about OS, and propose avenues of research in dietary intervention, discussing strategies that could potentially be effective to target OS metabolism.

OLIE, ITCC-082: a Phase II trial of lenvatinib plus ifosfamide and etoposide in relapsed/refractory osteosarcoma

While survival rates for patients with relapsed/refractory osteosarcoma are low, kinase inhibitors have shown efficacy in its treatment. The multikinase inhibitor lenvatinib, plus ifosfamide and etoposide, showed antitumor activity in a Phase II study in patients with relapsed/refractory osteosarcoma. This Phase II randomized controlled trial (OLIE) will assess whether the combination of lenvatinib + ifosfamide + etoposide is superior to ifosfamide + etoposide alone in children, adolescents and young adults with relapsed/refractory osteosarcoma. The primary end point is progression-free survival; secondary and exploratory end points include, but are not limited to, overall survival, objective response rate, safety and tolerability, pharmacokinetic characterization of lenvatinib in the combination treatment, quality of life and quantification of baseline unresectable lesions that are converted to resectable.

Primary and radiation induced skull base osteosarcoma: a systematic review of clinical features and treatment outcomes

PURPOSE

We aim to systematically review and summarize the demographics, clinical features, management strategies, and clinical outcomes of primary and radiation-induced skull-base osteosarcoma (SBO).

METHODS

PubMed, Scopus, and Cochrane databases were used to identify relevant articles. Papers including SBO cases and sufficient clinical outcome data were included. A comprehensive clinical characteristic review and survival analysis were also conducted.

RESULTS

Forty-one studies describing 67 patients were included. The median age was 31 years (male = 59.7%). The middle skull-base was most commonly involved (52.7%), followed by anterior (34.5%) and posterior (12.7%) skull-base. Headache (27%), exophthalmos (18%), and diplopia (10%) were common presenting symptoms. Sixty-eight percent of patients had primary SBO, while 25% had radiation-induced SBO. Surgery was the main treatment modality in 89% of cases. Chemotherapy was administered in 65.7% and radiotherapy in 50%. Median progression-free survival (PFS) was 12 months, and the overall 5-year survival was 22%. The five-year survival rates of radiation-induced SBO and primary SBO were 39% and 16%, respectively (P < 0.05).

CONCLUSION

SBO is a malignant disease with poor survival outcomes. Surgical resection is the primary management modality, in conjunction with chemotherapy and radiotherapy. Radiation-induced SBO has a superior survival outcome as compared to its primary counterpart. Complete surgical resection showed a statistically insignificant survival benefit as compared to partial resection.

Inhibition of the Notch signaling pathway attenuates progression of cell motility, metastasis, and epithelial-to-mesenchymal transition-like phenomena induced by low concentrations of cisplatin in osteosarcoma

Although advances in osteosarcoma treatment have been made in recent decades, the survival rate for patients suffering from metastatic disease, especially lung metastasis, remains disappointing. Previous studies have confirmed that epithelial-to-mesenchymal transition (EMT) is associated with tumor metastasis, and several studies have suggested that osteosarcoma cells also exhibit EMT-like characteristics. In addition, Notch signaling is known to be related to the development and progression of human malignancies, including osteosarcoma. However, whether chemotherapy affects the EMT-like events and whether these events are medicated by Notch signaling remain to be elucidated. To address these issues, in the current work, osteosarcoma 143B cells were exposed to sublethal concentrations of the first-line chemotherapeutic agent cisplatin (DDP), which promoted cell migration, in vitro invasion, and in vivo lung metastasis. Furthermore, low concentrations of DDP upregulated mesenchymal phenotype-related genes and proteins and promoted EMT-like properties in osteosarcoma cells. In addition, low concentrations of DDP could activate the Notch receptor and its target genes. Finally, combined treatment of DDP with the Notch signaling pathway inhibitor DAPT, which can effectively downregulate mesenchymal phenotype-related genes and proteins, inhibited cell migration and invasion in vitro, and it decreased pulmonary metastatic nodules in vivo. The results of the current study supported the idea that low concentrations of DDP could induce EMT-like characteristics in osteosarcoma cells and could promote cell mobility in vitro, as well as pulmonary metastasis in vivo. Importantly, however, these biological processes are mediated by the Notch signaling pathway. Blocking the Notch signaling pathway can effectively attenuate the osteosarcoma EMT-like phenotype and its associated migration, invasion, and metastasis.

Roles of Parathyroid Hormone-Related Protein (PTHrP) and Its Receptor (PTHR1) in Normal and Tumor Tissues: Focus on Their Roles in Osteosarcoma

Osteosarcoma (OS) is the most common primary bone tumor and originates from bone forming mesenchymal cells and primarily affects children and adolescents. The 5-year survival rate for OS is 60 to 65%, with little improvement in prognosis during the last four decades. Studies have demonstrated the evolving roles of parathyroid hormone-related protein (PTHrP) and its receptor (PTHR1) in bone formation, bone remodeling, regulation of calcium transport from blood to milk, regulation of maternal calcium transport to the fetus and reabsorption of calcium in kidneys. These two molecules also play critical roles in the development, progression and metastasis of several tumors such as breast cancer, lung carcinoma, chondrosarcoma, squamous cell carcinoma, melanoma and OS. The protein expression of both PTHrP and PTHR1 have been demonstrated in OS, and their functions and proposed signaling pathways have been investigated yet their roles in OS have not been fully elucidated. This review aims to discuss the latest research with PTHrP and PTHR1 in OS tumorigenesis and possible mechanistic pathways.

This review is dedicated to Professor Michael Day who died in May 2020 and was a very generous collaborator.

Radiological Assessment and Outcome of Local Disease Progression after Neoadjuvant Chemotherapy in Children and Adolescents with Localized Osteosarcoma

Objective: We examined the interobserver reliability of local progressive disease (L-PD) determination using two major radiological response evaluation criteria systems (Response evaluation Criteria in Solid Tumors (RECIST) and the European and American Osteosarcoma Study (EURAMOS)) in patients diagnosed with localized osteosarcoma (OS). Additionally, we describe the outcomes of patients determined to experience L-PD. Materials and Methods: Forty-seven patients diagnosed with localized OS between 2000 and 2012 at our institution were identified. Paired magnetic resonance imaging of the primary tumor from diagnosis and post-neoadjuvant chemotherapy were blindly assessed by two experienced radiologists and determined L-PD as per RECIST and EURAMOS radiological criteria. Interobserver reliability was measured using the kappa statistic (κ). The Kaplan Meier method and log-rank test was used to assess differences between groups. Results: Of 47 patients (median age at diagnosis 12.9 years), 16 (34%) had L-PD (by RECIST or EURAMOS radiological definition). There was less agreement between the radiologists using EURAMOS radiological criteria for L-PD (80.9%, κ = 0.48) than with RECIST criteria (97.9%, κ = 0.87). Patients with radiologically defined L-PD had a 5-year progression-free survival (PFS) of 55.6%, compared to a 5 year-PFS of 82.7% in the group of patients without L-PD (n = 31) (Log rank p = 0.0185). Conclusions: The interobserver reliability of L-PD determination is higher using RECIST than EURAMOS. RECIST can be considered for response assessment in OS clinical trials. The presence of L-PD was associated with worse outcomes.

Local administration of IL-12 with an HC vector results in local and metastatic tumor control in pediatric osteosarcoma

Osteosarcoma is the most frequent and aggressive bone tumor in children and adolescents, with a long-term survival rate of 30%. Interleukin-12 (IL-12) is a potent cytokine that bridges innate and adaptive immunity, triggers antiangiogenic responses, and achieves potent antitumor effects. In this work, we evaluated the antisarcoma effect of a high-capacity adenoviral vector encoding mouse IL-12. This vector harbored a mifepristone-inducible system for controlled expression of IL-12 (High-Capacity adenoviral vector enconding the EF1α promoter [HCA-EFZP]-IL-12). We found that local administration of the vector resulted in a reduction in the tumor burden, extended overall survival, and tumor eradication. Moreover, long-term survivors exhibited immunological memory when rechallenged with the same tumor cells. Treatment with HCA-EFZP-IL-12 also resulted in a significant decrease in lung metastasis. Immunohistochemical analyses showed profound remodeling of the osteosarcoma microenvironment with decreases in angiogenesis and macrophage and myeloid cell numbers. In summary, our data underscore the potential therapeutic value of IL-12 in the context of a drug-inducible system that allows controlled expression of this cytokine, which can trigger a potent antitumor immune response in primary and metastatic pediatric osteosarcoma.

Expression and clinical implications of leucine-rich repeat containing 15 (LRRC15) in osteosarcoma

Leucine-rich repeat containing 15 (LRRC15) is a member of the leucine-rich repeat superfamily that is overexpressed in various cancers and associated with higher tumor grade and aggression. Despite its known tumorigenicity, its roles within osteosarcoma are unknown, prompting us to evaluate its expression and clinical significance within this rare yet aggressive cancer. Western blots showed differential expression of LRRC15 in the osteosarcoma cell lines MNNG/HOS, KHOS, 143B, MG63, Saos-2, and U2OS. We additionally validated this positive expression, as well as sublocalization to the cell membrane, with immunofluorescence. A tissue microarray constructed from 69 osteosarcoma patient tissues was immunohistochemically stained for LRRC15 expression, stratified, and used for clinicopathological analysis. Publicly available databases on LRRC15 expression, including RNA sequencing data from the Therapeutically Applicable Research to Generate Effective Treatments on Osteosarcoma (TARGET-OS) and the Gene Expression database of Normal and Tumor tissues 2 (GENT2) were also analyzed. We found 63 of the 69 (91.3%) patient tissues exhibited some degree of LRRC15 immunostaining, including no staining (6 of 69, 8.7%), 1+ staining (12 of 69, 17.4%), 2+ staining (25 of 69, 36.2%), and 3+ staining (26 of 69, 37.7%). The patients with osteosarcomas having elevated LRRC15 expression demonstrated comparatively increased metastasis, chemoresistance, and shorter 5-year survival rates. Our analysis of the TARGET-OS and GENT2 databases also showed increased LRRC15 gene expression in osteosarcoma. Taken together, our study supports LRRC15 as a prognostic biomarker and emerging therapeutic target in osteosarcoma.

Targeting Mechanotransduction in Osteosarcoma: A Comparative Oncology Perspective

Mechanotransduction is the process in which cells can convert extracellular mechanical stimuli into biochemical changes within a cell. While this a normal process for physiological development and function in many organ systems, tumour cells can exploit this process to promote tumour progression. Here we summarise the current state of knowledge of mechanotransduction in osteosarcoma (OSA), the most common primary bone tumour, referencing both human and canine models and other similar mesenchymal malignancies (e.g., Ewing sarcoma). Specifically, we discuss the mechanical properties of OSA cells, the pathways that these cells utilise to respond to external mechanical cues, and mechanotransduction-targeting strategies tested in OSA so far. We point out gaps in the literature and propose avenues to address them. Understanding how the physical microenvironment influences cell signalling and behaviour will lead to the improved design of strategies to target the mechanical vulnerabilities of OSA cells.

Decreased long non-coding RNA lincFOXF1 indicates poor progression and promotes cell migration and metastasis in osteosarcoma

Long non‐coding RNAs have been demonstrated to be important regulators of various cancers, though the precise mechanisms remain unclear. Although lincFOXF1 has been reported to act as a tumour suppressor, its function and underlying mechanisms in osteosarcoma have not yet been explored. We employed quantitative real‐time polymerase chain reaction (qRT‐PCR) to evaluate the expression of lincFOXF1 and GAPDH in osteosarcoma tissues and cell lines, and colony‐formation, CCK8, wound‐healing, and transwell assays were conducted to analyse the proliferation, migration, and invasion capacity of osteosarcoma cells. Subcellular localization analysis by fractionation and RNA immunoprecipitation assays were performed to elucidate the mechanism responsible for lincFOXF1‐mediated phenotypes of osteosarcoma cells. The results revealed that lincFOXF1 expression is significantly decreased and strongly related to Enneking stage as well as metastasis in osteosarcoma patients. Further experiments showed that lincFOXF1 inhibits the migration, invasion and metastasis of cells in vitro and vivo. Mechanistic investigation demonstrated that lincFOXF1 physically binds to EZH2, a polycomb repressive complex 2 (PRC2) component, and a search for downstream targets suggested that G‐protein‐coupled receptor kinase‐interacting protein 1 (GIT1) is involved in the lincFOXF1‐mediated repression of osteosarcoma cells migration and invasion. Moreover, GIT1 expression is inversely correlated with lincFOXF1 in osteosarcoma. The present findings indicate that lincFOXF1 is involved in the progression of osteosarcoma through binding with EZH2, further regulating GIT1 expression. Our results suggest that lincFOXF1 may serve as a biomarker and therapeutic target for osteosarcoma patients.

2-methylbenzoyl berbamine, a multi-targeted inhibitor, suppresses the growth of human osteosarcoma through disabling NF-κB, ERK and AKT signaling networks

Osteosarcoma is the most common malignant bone tumor in children and young adults, and it has a survival rate of only 60% with current cytotoxic chemotherapy combined with aggressive surgery. The aim of this study was to evaluate the therapeutic efficacy of the berbamine derivative 2-methylbenzoyl berbamine (BBD24) for osteosarcoma in vitro and in vivo. We used human osteosarcoma cell lines, primary osteosarcoma cells and mouse models to evaluate the inhibitory effects of BBD24 on osteosarcoma and to determine the molecular mechanism. Our results showed that BBD24 inhibited the growth of the human osteosarcoma cell lines HOS and MG63 in a time- and dose-dependent manner. BBD24 also exhibited significant inhibitory effects on primary osteosarcoma cells. In contrast, BBD24 did not affect normal blood cells under the same conditions. Treatment with BBD24 induced apoptosis, necrosis and autophagy in osteosarcoma cells. Western blot analysis revealed that BBD24 activated the caspase-dependent pathway and downregulated the NF-kB, AKT, and ERK pathways. Finally, BBD24 treatment induced a significant inhibitory effect on the growth of osteosarcoma in nude mice. Our findings indicate that BBD24 is a multitarget inhibitor and may represent a new type of anticancer agent for osteosarcoma treatment.

Development of Natural-Based Bone Cement for a Controlled Doxorubicin-Drug Release

Osteosarcoma (OS) accounts for 60% of all global bone cancer diagnoses. Intravenous administration of Doxorubicin Hydrochloride (DOXO) is the current form of OS treatment, however, systemic delivery has been linked to the onset of DOXO induced cardiomyopathy. Biomaterials including calcium phosphate cements (CPCs) and nanoparticles (NPs) have been tested as localized drug delivery scaffolds for OS cells. However, the tumor microenvironment is critical in cancer progression, with mesenchymal stem cells (MSCs) thought to promote OS metastasis and drug resistance. The extent of MSC assisted survival of OS cells in response to DOXO delivered by CPCs is unknown. In this study, we aimed at investigating the effect of DOXO release from a new formulation of calcium phosphate-based bone cement on the viability of OS cells cocultured with hMSC in vitro. NPs made of PLGA were loaded with DOXO and incorporated in the formulated bone cement to achieve local drug release. The inclusion of PLGA-DOXO NPs into CPCs was also proven to increase the levels of cytotoxicity of U2OS cells in mono- and coculture after 24 and 72 h. Our results demonstrate that a more effective localized DOXO delivery can be achieved via the use of CPCs loaded with PLGA-DOXO NPs compared to CPCs loaded with DOXO, by an observed reduction in metabolic activity of U2OS cells in indirect coculture with hMSCs. The presence of hMSCs offer a degree of DOXO resistance in U2OS cells cultured on PLGA-DOXO NP bone cements. The consideration of the tumor microenvironment via the indirect inclusion of hMSCs in this study can act as a starting point for future direct coculture and in vivo investigations.

Long Non-coding RNA MRUL Contributes to Osteosarcoma Progression Through the miR-125a-5p/FUT4 Axis

Osteosarcoma (OS) originates in the skeletal system and has a rising global incidence. Long Non-coding RNAs (lncRNAs) are key regulators of human cancers development and progression. However, their roles in the development of OS are not well understood. This research aimed to investigate the effect of a long non-coding RNA (lncRNA), MRUL, on OS and revealed its potential molecular mechanisms. The bioinformatics analysis demonstrated that lncRNA MRUL was involved in regulating nucleic acid-templated transcription, cellular macromolecule biosynthetic process, immune response, and inflammatory response. In this work, the expression of lncRNA MRUL was detected by quantitative real-time polymerase chain reaction (qRT-RCR) in both cancer tissues and cell lines. We found that lncRNA MRUL was up-regulated in cancer tissues and cell lines. Functional experiments showed that knockdown of lncRNA MRUL inhibited OS cell proliferation, and metastasis. At the same time, we found that lncRNA MRUL interacted with miR-125a-5p to suppress FUT4 expression. Moreover, inhibition of miR-125a-5p abrogated the biological roles of lncRNA MRUL knockdown on OS cell proliferation, migration, and invasion. In conclusion, these results demonstrated that OS-upregulated lncRNA MRUL promoted cell proliferation, and metastasis via negatively regulating miR-125a-5p, and imply that lncRNA MRUL may be a potential biomarker for OS.

miR-429 inhibits osteosarcoma progression by targeting HOXA9 through suppressing Wnt/β-catenin signaling pathway

Osteosarcoma (OS) is the most commonly diagnosed malignant cancer of bone that occurs in adolescents and children. Mounting number of studies have indicated that miRNAs are increasingly playing fundamental roles in OS development. Thus, the biological function of miR-429 in OS progression was explored. The results of RT-qPCR revealed that miR-429 was downregulated in OS tissues and OS cell lines (MG-63, U2OS, Saos-2) while homeobox A9 (HOXA9) was markedly increased. Moreover, HOXA9 was confirmed as a direct target of miR-429 by using luciferase reporter assay. It was identified that miR-429 exhibited a suppressive effect on OS progression while HOXA9 showed the oncogenic function in OS progression by using MTT and Transwell assays. More importantly, rescue assays manifested that HOXA9 can partially overturn the suppressive effect of miR-429 on OS. Overexpression of miR-429 inhibited the activation of Wnt/β-catenin signaling pathway. In conclusion, miR-429 suppressed OS progression by targeting HOXA9 through Wnt/β-catenin pathway.

Small direct right ventricular cardiac metastasis of osteosarcoma in a 10-year-old boy affirmed by cardiac MRI

Background

Metastatic osteosarcoma with direct cardiac involvement is an exceptionally rare finding. Reliable detection of cardiac metastases is known to be crucial for patients therapy and prognosis.

Case Summary

In a 10-year-old boy affected by osteosarcoma of the left femur, a baseline Fluorine-18-fluorodeoxy-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) was performed to assess the full extent of disease. Whole-body scan detected numerous bone metastases together with a single pulmonary metastasis. Moreover, increased tracer uptake was observed in the intracavitary right cardiac ventricle in the position of a subtle spot of calcification. Because of nondetectability of a cavitary lesion on echocardiography, cardiac magnetic resonance imaging (CMRI) examination was performed to evaluate cardiac ¹⁸F-FDG PET/CT finding. CMRI revealed a small nodule in the right ventricle attached to the trabeculae, highly suspicious of a direct cardiac metastasis. After 4 cycles of chemotherapy, complete regression of tracer uptake of the lesion was observed on a follow-up ¹⁸F-FDG PET/CT scan.

Conclusion

CMRI is able to detect even small, clinically asymptomatic cardiac metastases in young patients affected by osteosarcoma.

MicroRNA-150 functions as a tumor suppressor and sensitizes osteosarcoma to doxorubicin-induced apoptosis by targeting RUNX2

Osteosarcoma (OS) is the most common form of bone malignancy in children and adolescents. MicroRNAs (miRNAs) have been associated with the development and progression of OS. In the present study, reverse transcription-quantitative PCR, western blotting, Cell Counting Kit-8, luciferase and Transwell assays were performed to investigate the biological function of microRNA-150 (miR-150) in OS. The results revealed that miR-150 was significantly downregulated in OS cell lines (HOS, SAOS2, MG-63 and U2OS) in comparison with the normal osteoblast cells (hFOB1.19). Overexpression of miR-150 significantly inhibited cell proliferation in OS cells. miR-150 could sensitize OS cells to chemotherapy treatment of doxorubicin. Runt-related transcription factor 2 (RUNX2) was identified as a target gene of miR-150. RUNX2 knockdown exhibited similar inhibitory effects on both OS cell proliferation and chemotherapy sensitivity. Restoration of RUNX2 reversed the biological function of miR-150. Finally, miR-150 overexpression and RUNX2 knockdown enhanced caspase-3 cleavage. Taken together, the present study established a novel molecular mechanism, in that miR-150 plays tumor suppressor and chemoprotective roles by targeting RUNX2 in OS, indicating that miR-150 may be a potential therapeutic target for OS therapy in the future.

Epigenetic Profiling Identifies LIF as a Super-enhancer-Controlled Regulator of Stem Cell-like Properties in Osteosarcoma

Osteosarcoma is an aggressive malignancy with poor prognosis. Super-enhancers (SE) have been highlighted as critical oncogenic elements required for maintaining the cancer cell characteristics. However, the regulatory role of SEs in osteosarcoma properties has not yet been elucidated. In the current study, we found that osteosarcoma cells and clinical specimens shared a significant fraction of SEs. Moreover, leukemia-inhibitory factor (LIF) was identified as an essential factor under the control of osteosarcoma-specific SE. The expression of LIF was positively correlated with the stem cell core factor genes in osteosarcoma. Furthermore, LIF recombinant protein-treated osteosarcoma cells displayed enhanced stem cell-like characteristics, such as increased sphere-forming potential, stimulated self-renewal, upregulated metastasis ability, and increased stemness-related gene expression. Notably, the histone 3 lysine 27 tri-methylation (H3K27me3) demethylase UTX was found as a key activator of LIF transcription in osteosarcoma. The UTX inhibitor, GSK-J4, induced H3K27me3 accumulation and impaired histone 3 lysine 27 acetylation (H3K27ac) at LIF gene locus, leading to LIF signaling pathway inhibition. GSK-J4 treatment resulted in profound defects in stem cell-like characteristics and stemness-related gene activation in osteosarcoma by modulating the H3K27ac of NOTCH1 signaling pathway gene loci. The NOTCH1 inhibitor Crenigacestat (TargetMol, T3633) repressed LIF-mediated activation of the stemness-related genes in osteosarcoma patient-derived primary tissues. IMPLICATIONS: This study reveals osteosarcoma SE profiles and uncovers a distinct tumor-stemness epigenetic regulatory mechanism in which an osteosarcoma-specific SE-mediated factor, LIF, promotes osteosarcoma stemness gene activation via NOTCH1 signaling pathway.

Primary Bone Tumors: Challenges and Opportunities for CAR-T Therapies

Primary malignant bone tumors are rare, occur in all age groups, and include distinct entities such as osteosarcoma, Ewing sarcoma, and chondrosarcoma. Traditional treatment with some combination of chemotherapy, surgery, and radiation has reached the limit of efficacy, with substantial room for improvement in patient outcome. Furthermore, genomic characterization of these tumors reveals a paucity of actionable molecular targets. Against this backdrop, recent advances in cancer immunotherapy represent a silver lining in the treatment of primary bone cancer. Major strategies in cancer immunotherapy include stimulating naturally occurring anti-tumor T cells and adoptive transfer of tumor-specific cytotoxic T cells. Chimeric antigen receptor T cells (CAR-T cells) belong to the latter strategy and are an impressive application of both insights into T cell biology and advances in genetic engineering. In this review, we briefly describe the CAR-T approach and discuss its applications in primary bone tumors. © 2019 American Society for Bone and Mineral Research.

MicroRNA-93 promotes the tumorigenesis of osteosarcoma by targeting TIMP2

Osteosarcoma (OS) is the most frequent primary bone malignancy and affects adolescents and young adults. Recently dysregulation of miRNAs has received more attention because of its extensive role in OS carcinogenesis. This research was designed to verify how microRNA-93 (miR-93) and tissue inhibitor of matrix metalloproteinase 2 (TIMP2) be involved in OS development. At first, the levels of miR-93 and its predictive target gene TIMP2 were detected in OS and osteoblast cell lines, and 62 pairs OS and adjacent non-OS specimens by real-time PCR and western blot. Then, viability, invasion, and epithelial mesenchymal transition (EMT) of OS cell lines were examined when overexpressed or knocked down miR-93, or overexpressed TIMP2. Finally, the interaction between miR-93 and TIMP2 was evaluated using mutation, gain, and loss experiment. Our data indicated that miR-93 was increased while TIMP2 was decreased in both OS cell lines and tissues. MiR-93 high-expression and TIMP2 low-expression were related with poor overall survival and prognosis of OS patients. Overexpression or knockdown experiment indicated that miR-93 enhanced OS cell viability, invasion, and EMT expression. TIMP2 could inhibit OS cell viability, invasion, and EMT expression. Further, miR-93 directly targeted TIMP2 and negatively regulated TIMP2 level in OS cells. And up-regulation of TIMP2 reversed the effects of miR-93 in OS. Finally, miR-93 regulated the oncogenic functions in OS cells by regulating the expression of TIMP2. In conclusion, our study demonstrates that miR-93 may exert an oncogenic function while TIMP2 may act as a tumor suppressor on OS.

Pediatric Osteosarcoma of Extremities: A 15-year Experience From a Tertiary Care Cancer Center in Upper Egypt

AIM

To assess the outcome and determine predictors of survival in pediatric patients with osteosarcoma of the extremities treated with a unified chemotherapy protocol at a single institution over a 15-year period.

MATERIALS AND METHODS

We performed a retrospective analysis of medical records of 48 pediatric patients with histologically verified osteosarcoma of the extremities diagnosed at South Egypt Cancer Institute and received treatment between January 2001 and December 2015.

RESULTS

With a median follow-up of 61 months for the entire cohort, estimates of overall survival (OS) for 3- and 5-year were 50.9% and 42.1%, respectively. While the estimates of OS for 3- and 5-year in the nonmetastatic group were 79% and 65.2%, respectively. In the multivariable analysis, both metastatic disease at diagnosis and poor response to chemotherapy retained their statistical significance as independent predictors for event-free survival. Whereas for OS, a metastatic disease at diagnosis remained as the lone predictor of a dismal outcome, while a poor response to chemotherapy became marginally associated with an inferior outcome.

CONCLUSIONS

In Upper Egypt, whereas slightly less than two thirds of children with localized osteosarcoma of extremities survives their disease, metastasis at presentation remains the key predictor of dismal survival outcomes.

Notch signaling regulates osteosarcoma proliferation and migration through Erk phosphorylation

We used a murine spontaneous osteosarcoma cell line with high metastatic potential, the K7M2 cell line to study the role of Notch signaling in the biological manifestations of osteosarcoma, to understand its underlying mechanism in the regulation of cell proliferation and migration, and to improve patient prognosis in cases of osteosarcoma through the discovery of novel therapeutic targets, First, Notch expression in K7M2 was determined by immunostaining, and the γ-secretase inhibitor N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT) was used to inhibit proteolytic cleavage of the Notch intracellular domain (NICD), resulting in the inhibition of Notch activation. By using the Sulforhodamine B assay, colony-forming units assay, Brdu and Ki67 staining, and flow cytometry assays of apoptosis and cell cycle stage, DAPT was found to inhibit K7M2 proliferation in a dose-dependent manner. By using wound healing and transwell migration assays, DAPT was found to inhibit K7M2 migration in a dose-dependent manner as well. By using a combination of micro-Raman spectroscopy and K-means clustering analysis, we found that DAPT inhibit a variety of important cell metabolism-related components in most K7M2 cell structures. Then, DAPT was found to inhibit Notch1ICD expression in a concentration-dependent manner, and this expression was directly correlated with Phospho-Erk1/2 (p-Erk) by using Western blotting. To confirm this finding, we used the Notch signaling ligand Jagged1 to activate the Notch signaling pathway, which in turn up-regulated p-Erk, resulting in increased proliferation and migration of K7M2. Using the Erk pathway inhibitor U0126, we showed that p-Erk was downregulated and the proliferation and migration of K7M2 decreased along with it. Finally, we constructed a K7M2 mouse para-tibial tumor model and lung metastatic model. We found DAPT inhibits p-Erk in vivo, effectively controls tumor growth, reduces angiogenesis, reduces metastasis to the lungs, and improves overall survival. In summary, Notch signaling plays an oncogene role and promotes metastasis in osteosarcoma through p-Erk. DAPT effectively inhibits osteosarcoma proliferation and metastasis in vivo and in vitro by inhibiting Erk phosphorylation. Therefore, the inhibition of Notch activation resulted the down-regulation of phosphorylation of Erk pathway can be used as potential therapeutic targets in clinical treatment to improve osteosarcoma prognosis.

Screening of disorders associated with osteosarcoma by integrated network analysis

Osteosarcoma is a common malignant bone tumor in children and adolescents under the age of 20. However, research on the pathogenesis and treatment of osteosarcoma is still insufficient. In the present study, based on gene-phenotype correlation network, an analysis was performed to screen disorders related to osteosarcoma. First, we analyzed the differential expression of osteosarcoma in two groups according to different types of osteosarcoma and screened the differentially expressed genes (DEGs) related to osteosarcoma. Further, these DEG coexpression modules were obtained. Finally, we identified a series of regulatory factors, such as endogenous genes, transcription factors (TFs), and ncRNAs, which have potential regulatory effects on osteosarcoma, based on the prediction analysis of related network of gene phenotypes. A total of 3767 DEGs of osteosarcoma were identified and clustered them into 20 osteosarcoma-related dysfunction modules. And there were 38 endogenous genes (including ARF1, HSP90AB1, and TUBA1B), 53 TFs (including E2F1, NFKB1, and EGR1), and 858 ncRNAs (including MALAT1, miR-590-3p, and TUG1) were considered as key regulators of osteosarcoma through a series of function enrichment analysis and network analysis. Based on the results of the present study, we can show a new way for biologists and pharmacists to reveal the potential molecular mechanism of osteosarcoma typing, and provide valuable reference for different follow-up treatment options.

Upregulation of microRNA-7 contributes to inhibition of the growth and metastasis of osteosarcoma cells through the inhibition of IGF1R

We aim to uncover the methylation of microRNA-7 (miR-7) promoter in osteosarcoma (OS) and the inner mechanism of miR-7 on the progression of OS cells. Expression and methylation state of miR-7 in OS tissues and cells were detected. With the aim to unearth the ability of miR-7 in OS, the proliferation, cell cycle progression, apoptosis, invasion, migration of OS cells, and the tumor growth in nude mice were determined. Meanwhile, IGF1R expression was detected and the association between miR-7 and IGF1R was confirmed. The proliferating cell nuclear antigen (PCNA) expression was tested by immunohistochemical staining, and the lung metastasis was observed by H&E staining. miR-7 expression was decreased and methylation state of miR-7 was increased in OS tissues and cells. Upregulated miR-7 inhibited proliferation, cell cycle progression, invasion,and migration, while inducing apoptosis of OS cells and the tumor growth as well as PCNA expression in nude mice. Expression of IGF1R was downregulated in OS cells with overexpression of miR-7. Experiments verified the binding site between miR-7 and IGF1R. Our study demonstrates that abnormal methylation of miR-7 contributes to decreased miR-7 in OS. In addition, miR-7 represses the initiation and progression of OS cells through the inhibition of IGF1R.

ATF6α Activation Enhances Survival against Chemotherapy and Serves as a Prognostic Indicator in Osteosarcoma

Patients with metastatic or relapsed/refractory osteosarcoma (OS) have a 5-year survival rate of <30%. This has remained unchanged over several decades. One of the factors contributing to lack of improvement in survival is the development of chemoresistance. Hence, elucidating and targeting the mechanisms that promote survival against chemotherapy and lead to chemoresistance is pivotal to improving outcomes for these patients. We identified that endoplasmic reticulum (ER) stress-activated transcription factor, ATF6α, is essential for the survival of OS cells against chemotherapy induced cell death. ATF6α cleavage and activity were enhanced in OS cells compared to normal osteoblasts and knockdown of ATF6α expression enhanced sensitivity of OS cells against chemotherapy induced cell death. This was in part due to increased Bax activation. Pharmacologic inhibition or knock-down of downstream targets of ATF6α, protein disulfide isomerases (PDI) and ERO1β, a thiol oxidase that is involved in the re-oxidation of PDIs also independently induced pronounced killing of OS cells following chemotherapy. Analysis of primary tumors from OS patients reveals that patients with high levels of nuclear ATF6α: (1) also had increased expression of its downstream targets the chaperone BiP and enzyme PDI, (2) had a significant likelihood of developing metastasis at diagnosis, (3) had significantly poorer overall and progression free survival, and (4) had poorer response to chemotherapy. These findings suggest that targeting survival signaling by the ATF6α pathway in OS cells may favor eradication of refractory OS tumor cells and ATF6α could be a useful predictor for chemo-responsiveness and prognosis.

A comparison of risk factors for metastasis at diagnosis in humans and dogs with osteosarcoma

Background

Canine osteosarcoma (OS) is a relevant spontaneous model for human OS. Identifying similarities in clinical characteristics associated with metastasis at diagnosis in both species may substantiate research aimed at using canine OS as a model for identifying mechanisms driving distant spread in the human disease.

Methods

This retrospective study included dog OS cases from three academic veterinary hospitals and human OS cases from the Surveillance, Epidemiology, and End Results program. Associations between clinical factors and metastasis at diagnosis were estimated using logistic regression models.

Results

In humans, those with trunk tumors had higher odds of metastasis at diagnosis compared to those with lower limb tumors (OR = 2.38, 95% CI: 1.51, 3.69). A similar observation was seen in dogs with trunk tumors compared to dogs with forelimb tumors (OR = 3.28, 95% CI 1.36, 7.50). Other associations were observed in humans but not in dogs. Humans aged 20‐29 years had lower odds of metastasis at diagnosis compared to those aged 10‐14 years (OR = 0.67, 95% CI: 0.47, 0.96); every 1‐cm increase in tumor size was associated with a 6% increase in the odds of metastasis at diagnosis (95% CI: 1.04, 1.08); compared to those with a white, non‐Hispanic race, higher odds were observed among those with a black, non‐Hispanic race (OR: 1.51, 95% CI: 1.04, 2.16), and those with a Hispanic origin (OR 1.35, 95% CI: 1.00, 1.81).

Conclusion

A common mechanism may be driving trunk tumors to progress to detectable metastasis prior to diagnosis in both species.

Association of GSTM1, GSTT1, GSTM3, and GSTP1 Genes Polymorphisms with Susceptibility to Osteosarcoma: a Case- Control Study and Meta-Analysis

Background: Some studies have investigated the association of GSTM1, GSTT1, GSTM3, and GSTP1 polymorphisms with susceptibility to osteosarcoma; however, these studies results are inconsistent and inconclusive. In order to drive a more precise estimation, the present case-control study and meta-analysis was performed to investigate association of GSTM1, GSTT1, GSTM3, and GSTP1 polymorphisms with osteosarcoma. Methods: Eligible articles were identified by a search of several electronic databases for the period up to May 5, 2018. Odds ratios were pooled using either fixed-effects or random effects models. Results: Finally, a total of 24 case-control studies with 2,405 osteosarcoma cases and 3,293 controls were included in the present meta-analysis. Overall, significantly increased osteosarcoma risk was found when all studies were pooled into the meta-analysis of GSTT1 (Null vs. Present: OR= 1.247 95% CI 1.020-1.524, P= 0.031) and GSTP1 polymorphism (B vs. A: OR= 8.899 95% CI 2.722-29.094, P≤0.001). In the stratified, significantly increased osteosarcoma risk was observed for GSTT1 polymorphism among Asians (Null vs. Present: OR= 1.300 95% CI 1.034-1.635, P= 0.025), but not among Caucasians. Conclusions: This meta-analysis demonstrated that GSTP1 and GSTT1 null genotype are associated with the risk of osteosarcoma. Future large welldesigned epidemiological studies are warranted to validate our results.

microRNA-138-5p as a Worse Prognosis Biomarker in Pediatric, Adolescent, and Young Adult Osteosarcoma

Osteosarcoma (OS) is the most common primary malignant bone tumor with two peaks of incidence, in early adolescence and the elderly. Patients affected with this malignancy often present metastatic disease at diagnosis, and despite multimodality therapy, survival has not improved substantially over the past 3 decades. Recently, miR-138-5p, proposed as a crucial intracellular mediator of invasion, has been recognized to target the Rho-associated coiled-coil containing protein kinase 2 (ROCK2). Dysregulation of ROCK1 and ROCK2 was also described in OS, being associated to higher metastasis incidence and worse prognosis. Nonetheless, the specific roles of miR-138-5p in pediatric and young adult OS and its ability to modulate these kinases remain to be established. Thus, in the present study, the expression levels miR-138-5p were evaluated in a consecutive cohort of exclusively pediatric and young adult primary OS samples. In contrast to previous reports that included adult tissues, our results showed upregulation of miR-138-5p associated with reduced event-free survival and relapsed cases. In parallel, ROCK1 mRNA levels were significantly reduced in tumor samples and negatively correlated with miR-138-5p. Similar correlations were observed after studying the profiles of ROCK1 and ROCK2 by immunohistochemistry. Our data present miR-138-5p as a consistent prognostic factor in pediatric and young adult OS, reinforcing its participation in the post-transcriptional regulation of ROCK kinases.

Role of microRNA-92a in metastasis of osteosarcoma cells in vivo and in vitro by inhibiting expression of TCF21 with the transmission of bone marrow derived mesenchymal stem cells

Background

This study aims to investigate the role of microRNA-92a (miR-92a) in metastasis of osteosarcoma (OS) cells in vivo and in vitro by regulatingTCF21 with the transmission of bone marrow derived mesenchymal stem cells (BMSCs).

Methods

BMSCs were isolated, purified and cultured from healthy adult bone marrow tissues. The successfully identified BMSCs were co-cultured with OS cells, and the effects of BMSCs on the growth metastasis of OS cells in vitro and in vivo were determined. qRT-PCR and western blot analysis was used to detect the expression of miR-92a and TCF21 in OS cells and OS cells co-cultured with BMSCs. Proliferation, invasion and migration of OS cells transfected with miR-92a mimics and miR-92a inhibitors was determined, and the tumorigenesis and metastasis of OS cells in nude mice were observed. Expression of miR-92a and TCF21 mRNA in tissue specimens as well as the relationship between the expression of miR-92a and the clinicopathological features of OS was analyzed.

Results

BMSCs promoted proliferation, invasion and migration of OS cells in vitro together with promoted the growth and metastasis of OS cells in vivo. Besides, high expression of miR-92a was found in OS cells co-cultured with BMSCs. Meanwhile, overexpression of miR-92a promoted proliferation, invasion and migration of OS cells in vitro as well as promoted growth and metastasis of OS cells in vivo. The expression of miR-92a increased significantly, and the expression of TCF21 mRNA and protein decreased significantly in OS tissues. Expression of miR-92a was related to Ennecking staging and distant metastasis in OS patients.

Conclusion

Collectively, this study demonstrates that the expression of miR-92a is high in OS and BMSCs transfers miR-92a to inhibit TCF21 and promotes growth and metastasis of OS in vitro and in vivo.