Imatinib mesylate exerts anti-proliferative effects on osteosarcoma cells and inhibits the tumour growth in immunocompetent murine models

Advancing the Management of Skull Base Chondrosarcomas: A Systematic Review of Targeted Therapies

Background: Chondrosarcomas rank as the second most common primary bone malignancy. Characterized by the production of a cartilaginous matrix, these tumors typically exhibit resistance to both radiotherapy (RT) and chemotherapy (CT), resulting in overall poor outcomes: a high rate of mortality, especially among children and adolescents. Due to the considerable resistance to current conventional therapies such as surgery, CT, and RT, there is an urgent need to identify factors contributing to resistance and discover new strategies for optimal treatment. Over the past decade, researchers have delved into the dysregulation of genes associated with tumor development and therapy resistance to identify potential therapeutic targets for overcoming resistance. Recent studies have suggested several promising biomarkers and therapeutic targets for chondrosarcoma, including isocitrate dehydrogenase (IDH1/2) and COL2A1. Molecule-targeting agents and immunotherapies have demonstrated favorable antitumor activity in clinical studies involving patients with advanced chondrosarcomas. In this systematic review, we delineate the clinical features of chondrosarcoma and provide a summary of gene dysregulation and mutation associated with tumor development, as well as targeted therapies as a promising molecular approach. Finally, we analyze the probable role of the tumor microenvironment in chondrosarcoma drug resistance. Methods: A systematic search was conducted across major medical databases (PubMed, Embase, and Cochrane Library) up to 10 November 2023. The search strategy utilized relevant Medical Subject Heading (MeSH) terms and keywords related to “chondrosarcomas”, “target therapies”, “immunotherapies”, and “outcomes”. The studies included in this review consist of randomized controlled trials, non-randomized controlled trials, and cohort studies reporting on the use of target therapies for the treatment of chondrosarcoma in human subjects. Results: Of the initial 279 articles identified, 40 articles were included in the article. The exclusion of 140 articles was due to reasons such as irrelevance, non-reporting of selected results, systematic literature review or meta-analysis, and lack of details on the method/results. Three tables highlighted clinical studies, preclinical studies, and ongoing clinical trials, encompassing 13, 7, and 20 studies, respectively. For the clinical study, a range of molecular targets, such as death receptors 4/5 (DR4 and DR5) (15%), platelet-derived growth factor receptor-alpha or -beta (PDGFR-α, PDGFR-β) (31%), were investigated. Adverse events were mainly constitutional symptoms emphasizing that to improve therapy tolerance, careful observation and tailored management are essential. Preclinical studies analyzed various molecular targets such as DR4/5 (28.6%) and COX-2 (28.6%). The prevalent indicator of antitumoral activity was the apoptotic rate of both a single agent (tumor necrosis factor-related apoptosis-inducing ligand: TRAIL) and double agents (TRAIL-DOX, TRAIL-MG132). Ongoing clinical trials, the majority in Phase II (53.9%), highlighted possible therapeutic strategies such as IDH1 inhibitors and PD-1/PD-L1 inhibitors (30.8%). Conclusions: The present review offers a comprehensive analysis of targeted therapeutics for skull base chondrosarcomas, highlighting a complex landscape characterized by a range of treatment approaches and new opportunities for tailored interventions. The combination of results from molecular research and clinical trials emphasizes the necessity for specialized treatment strategies and the complexity of chondrosarcoma biology.

Cancer characterization using light backscattering spectroscopy and quantitative ultrasound: an ex vivo study on sarcoma subtypes

Histological analysis is the gold standard method for cancer diagnosis. However, it is prone to subjectivity and sampling bias. In response to these limitations, we introduce a quantitative bimodal approach that aims to provide non-invasive guidance towards suspicious regions. Light backscattering spectroscopy and quantitative ultrasound techniques were combined to characterize two different bone tumor types from animal models: chondrosarcomas and osteosarcomas. Two different cell lines were used to induce osteosarcoma growth. Histological analyses were conducted to serve as references. Three ultrasound parameters and intensities of the light reflectance profiles showed significant differences between chondrosarcomas and osteosarcomas at the 5% level. Likewise, variations in the same biomarkers were reported for the two types of osteosarcoma, despite their similar morphology observed in the histological examinations. These observations show the sensitivity of our techniques in probing fine tissue properties. Secondly, the ultrasound spectral-based technique identified the mean size of chondrosarcoma cells and nuclei with relative errors of about 22% and 9% respectively. The optical equivalent technique correctly extracted scatterer size distributions that encompass nuclei and cells for chondrosarcomas and osteosarcomas ([Formula: see text] and [Formula: see text] respectively). The optical scattering contributions of nuclei were estimated at 52% for the chondrosarcomas and 69% for the osteosarcomas, probably indicating the abundant and the absent extracellular matrix respectively. Thus, the ultrasound and the optical methods brought complementary parameters. They successfully estimated morphological parameters at the cellular and the nuclear scales, making our bimodal technique promising for tumor characterization.

Targeting signaling pathways in osteosarcoma: Mechanisms and clinical studies

Osteosarcoma (OS) is a highly prevalent bone malignancy among adolescents, accounting for 40% of all primary malignant bone tumors. Neoadjuvant chemotherapy combined with limb-preserving surgery has effectively reduced patient disability and mortality, but pulmonary metastases and OS cells' resistance to chemotherapeutic agents are pressing challenges in the clinical management of OS. There has been an urgent need to identify new biomarkers for OS to develop specific targeted therapies. Recently, the continued advancements in genomic analysis have contributed to the identification of clinically significant molecular biomarkers for diagnosing OS, acting as therapeutic targets, and predicting prognosis. Additionally, the contemporary molecular classifications have revealed that the signaling pathways, including Wnt/β-catenin, PI3K/AKT/mTOR, JAK/STAT3, Hippo, Notch, PD-1/PD-L1, MAPK, and NF-κB, have an integral role in OS onset, progression, metastasis, and treatment response. These molecular classifications and biological markers have created new avenues for more accurate OS diagnosis and relevant treatment. We herein present a review of the recent findings for the modulatory role of signaling pathways as possible biological markers and treatment targets for OS. This review also discusses current OS therapeutic approaches, including signaling pathway-based therapies developed over the past decade. Additionally, the review covers the signaling targets involved in the curative effects of traditional Chinese medicines in the context of expression regulation of relevant genes and proteins through the signaling pathways to inhibit OS cell growth. These findings are expected to provide directions for integrating genomic, molecular, and clinical profiles to enhance OS diagnosis and treatment.

Imatinib-Functionalized Galactose Hydrogels Loaded with Nanohydroxyapatite as a Drug Delivery System for Osteosarcoma: In Vitro Studies

This study reports an impact of structure (XRPD, FT-IR) and surface morphology (SEM-EDS) of imatinib-functionalized galactose hydrogels, loaded and unloaded with nHAp, on osteosarcoma cell (Saos-2 and U-2OS) viability, levels of free oxygen radicals, and nitric oxide, levels of BCL-2, p53, and caspase 3 and 9, as well as glycoprotein-P activity. It was investigated how the rough surface of the crystalline hydroxyapatite-modified hydrogel affected amorphous imatinib (IM) release. The imatinib drug effect on cell cultures has been demonstrated in different forms of administration-directly to the culture or the hydrogels. Administration of IM and hydrogel composites could be expected to reduce the risk of multidrug resistance development by inhibiting P_gp.

Receptor Tyrosine Kinase Inhibitors for the Treatment of Recurrent and Unresectable Bone Sarcomas

Bone sarcomas are a heterogeneous group of rare tumors with a predominance in the young population. Few options of systemic treatment are available once they become unresectable and resistant to conventional chemotherapy. A better knowledge of the key role that tyrosine kinase receptors (VEGFR, RET, MET, AXL, PDGFR, KIT, FGFR, IGF-1R) may play in the pathogenesis of these tumors has led to the development of multi-target inhibitors (TKIs) that are progressively being incorporated into our therapeutic arsenal. Osteosarcoma (OS) is the most frequent primary bone tumor and several TKIs have demonstrated clinical benefit in phase II clinical trials (cabozantinib, regorafenib, apatinib, sorafenib, and lenvatinib). Although the development of TKIs for other primary bone tumors is less advanced, preclinical data and early trials have begun to show their potential benefit in advanced Ewing sarcoma (ES) and rarer bone tumors (chondrosarcoma, chordoma, giant cell tumor of bone, and undifferentiated pleomorphic sarcoma). Previous reviews have mainly provided information on TKIs for OS and ES. We aim to summarize the existing knowledge regarding the use of TKIs in all bone sarcomas including the most recent studies as well as the potential synergistic effects of their combination with other systemic therapies.

Mangiferin promotes osteogenic differentiation and alleviates osteoporosis in the ovariectomized mouse via the AXL/ERK5 pathway

Mangiferin is a xanthone glucoside extracted from multiple plants, which has been shown to inhibit bone resorption and alleviate osteoporosis. However, the effect of purified Mangiferin on osteoporosis and its specific mechanisms is unknown. This study aimed to explore whether Mangiferin can promote osteogenic differentiation and alleviate osteoporosis in ovariectomized (OVX) mice and explore the potential mechanisms. Different concentrations and durations of Mangiferin were applied to MC3T3-E1 cells. The optimal concentration and duration of Mangiferin were determined by evaluating the cell viability via cell count kit-8 (CCK-8). The gene and protein expressions of AXL, ERK5, and osteogenic differentiation markers, including BMP2, Collagen1, OPN, Osterix, and Runx2, were detected using western blotting, qRT-PCR, immunofluorescence, and flow cytometry. Mangiferin was administered to OVX mice, and the severity of osteoporosis was evaluated by H and E staining, immunohistochemistry (IHC), microscopic computed-tomography (micro-CT) scanning, western blotting, and immunofluorescence of bone tissue. We found that Mangiferin promoted osteogenic differentiation in a dose-dependent manner at concentrations less than 30 μM. The 30 μM Mangiferin significantly upregulated the expression of AXL, ERK5, and osteogenic differentiation, including the ALP activity, percentage of alizarin red, and the levels of osteogenic differentiation markers. However, these expression levels decreased when AXL was knocked down in MC3T3-E1 cells and it could not be rescued by Mangiferin. Mangiferin relieved osteoporosis in OVX mice without causing severe organ damage. This study concluded that Mangiferin promoted osteogenic differentiation of MC3T3-E1 cells and alleviated osteoporosis in OVX mice. The potential mechanism was via the AXL/ERK5 pathway.

cyy260 suppresses the proliferation, migration and tumor growth of osteosarcoma by targeting PDGFR-β signaling pathway

Osteosarcoma (OS) is a group of malignant tumors with high rates of malignancy and metastasis. OS most commonly affects adolescents and young individuals. However, owing to the lack of effective targeted treatments, the 5-year survival rate for OS is still around 20%. Thus, it is essential to develop effective drugs with low toxicity for OS treatment. In the present study, we investigated the antitumor effect and underlying mechanism of cyy260 in OS via suppressing PDGFR-β and its downstream pathway. We demonstrated that cyy260 inhibits OS cell proliferation and promotes apoptosis via inducing DNA damage and causing cell cycle arrest. More importantly, cyy260 also significantly inhibits tumor migration. Further analysis of molecular mechanisms confirmed that PDGFR-β and its downstream AKT, STAT3, and ERK were involved in the cyy260-mediated antitumor effect. Analysis of subcutaneously transplanted tumors in mice showed that cyy260 suppressed tumor cell growth and exhibited low toxicity in vivo. Collectively, these findings proved that cyy260 could serve as a promising PDGFR-β inhibitor for the treatment of OS.

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.

Discovery of Potent and Orally Bioavailable Platelet-Derived Growth Factor Receptor (PDGFR) Inhibitors for the Treatment of Osteosarcoma

Platelet-derived growth factor receptors (PDGFRs) are now considered promising targets for the treatment of osteosarcoma. Herein, the design, synthesis, and structure-activity relationships (SAR) of novel pyrimidine-2,4-diamine derivatives that selectively inhibit PDGFRα/β kinases have been studied. The screening cascades revealed that 7m was the preferred compound among these derivatives, with IC₅₀ values of 2.4 and 0.9 nM for PDGFRα and PDGFRβ, respectively. Moreover, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) experiment revealed that 7m has a substantial cytotoxic effect against all osteosarcoma cancer cell lines; 7m also displayed robust antitumor effects and low toxicity in a xenograft model. Additionally, 7m showed excellent bioavailability (F = 62.9%), suitable half-life (T_1/2 = 2.12 h), satisfactory metabolic stability, and weak CYP isoform inhibitory activity, suggesting that 7m is a potential drug candidate for PDGFR-driven osteosarcoma.

1,3,5-triazines inhibit osteosarcoma and avert lung metastasis in a patient-derived orthotopic xenograft mouse model with favorable pharmacokinetics

Objectives

Osteosarcoma is a major solid malignant tumor of bone, possessing significant burden on healthcare due to non-availability of specific anticancer agents. The current study was conducted to identify novel 1,3,5-triazine derivatives against osteosarcoma.

Materials and Methods

The compounds were synthesized in a straight-forward two-step reaction and subsequently tested against PI3K and mTOR kinase and anticancer activity against osteosarcoma cells (MG-63, U2-OS, and Saos-2). The effect of the most potent compound was evaluated on apoptosis and cell phase of Saos-2 cells. The pharmacological activity was further established in the patient-derived orthotopic xenograft (PDOX) mouse model.

Results

The developed compounds 8 (a-f) showed significant inhibitory activities against PI3K, mTOR, and OS cells. Among the tested series, compound 8a showed highly potent PI3K/mTOR inhibitory activity with significant anticancer activity against Saos-2 cells compared with Imatinib as standard. It also induces apoptosis and causes G2/M arrest in Saos-2 cells. Compound 8a significantly improved body weight, reduced tumor volume, and inhibited lung metastasis in athymic nude mice in a PDOX mouse model. It also showed optimal pharmacokinetic parameters in SD rats.

Conclusion

In summary, 1,3,5-triazine analogs were identified as new PI3K/mTOR inhibitors against osteosarcoma.

Imatinib mesylate inhibits androgen-independent PC-3 cell viability, proliferation, migration, and tumor growth by targeting platelet-derived growth factor receptor-α

AIM

The abnormal expression of oncogenic tyrosine kinase receptors such as platelet-derived growth factor receptors (PDGFRs) has been reported in cancer progression. However, the role of PDGFRs in the human androgen-independent prostate cancer PC-3 cell line is not well understood. Thus, this study examined the role of PDGFRs in androgen-independent PC-3 cells.

MAIN METHODS

PDGFR mRNA and protein expression was determined by quantitative real-time PCR and western blotting, respectively. The effects of the tyrosine kinase inhibitor imatinib (imatinib mesylate) and small interfering RNAs (siRNAs) were determined by a Cell Counting Kit-8 assay, bromodeoxyuridine assay, and Transwell migration assay. The in vivo effect of imatinib was analyzed using a tumor formation assay in nude mice.

KEY FINDINGS

PDGFRα was upregulated in androgen-independent PC-3 cells compared with normal prostate epithelial cells. PDGF-BB induced the phosphorylation of PDGFRα and downstream signaling molecules, including Akt, in a dose-dependent manner. Imatinib reduced the phosphorylation of the PDGFRα/Akt axis. Imatinib also suppressed the viability, proliferation, migration, and tumor growth of PC-3 cells. PDGFRα knockdown by siRNA decreased the viability and migration of PC-3 cells.

SIGNIFICANCE

These results demonstrated the distinct contribution of PDGFRα signaling to the proliferation and migration of PC-3 cells and suggested the potential for PDGFRα as a therapeutic target for metastatic and androgen-independent prostate cancer.

PDGFRβ Modulates Aerobic Glycolysis in Osteosarcoma HOS Cells via the PI3K/AKT/mTOR/c-Myc Pathway

Osteosarcoma is a malignant tumor abundant in vascular tissue, and its rich blood supply may have a significant impact on its metabolic characteristics. PDGFRβ is a membrane receptor highly expressed in osteosarcoma cells and vascular wall cells, and its effect on osteosarcoma metabolism needs to be further studied. In this study, we discussed the effect and mechanism of PDGFRβ on the glucose metabolism of osteosarcomaHOS cells. First, GSEA, Pearson's correlation test, and PPI correlation analysis indicated the positive regulation of PDGFRβ on aerobic glycolysis in osteosarcoma. The results of qPCR and western blot further confirmed the prediction of bioinformatics. Glucose metabolism experiments proved that PDGF/PDGFRβ couldeffectively promote the aerobic glycolysis of osteosarcoma cells. In addition, the mitochondrial membrane potential experiment proved that the metabolic change triggered by PDGFRβ was not caused by mitochondrial damage. PI3K pathway inhibitor LY294002 or MEK pathway inhibitor U0126, or Warburg effect inhibitor DCA was used to carry out western blot and glucose metabolism experiments, and the results showed that PDGFBB/PDGFRβ mainly activated the PI3K/AKT/mTOR/ c-Myc pathway to promote aerobic glycolysis in osteosarcoma HOS cells. The newly elucidated role of PDGFRβ provides a novel metabolic therapeutic target for osteosarcoma.

Fabrication of Imatinib Mesylate-Loaded Lactoferrin-Modified PEGylated Liquid Crystalline Nanoparticles for Mitochondrial-Dependent Apoptosis in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a major cause of concern as it has substantial morbidity associated with it. Previous reports have ascertained the antiproliferative activity of imatinib mesylate (IMS) against diverse types of carcinomas, but limited bioavailability has also been reported. The present study envisaged optimized IMS-loaded lactoferrin (LF)-modified PEGylated liquid crystalline nanoparticles (IMS-LF-LCNPs) for effective therapy of IMS to HCC via asialoglycoprotein receptor (ASGPR) targeting. Results displayed that IMS-LF-LCNPs presented an optimum particle size of 120.40 ± 2.75 nm, a zeta potential of +12.5 ± 0.23 mV, and 73.94 ± 2.69% release. High-resolution transmission electron microscopy and atomic force microscopy were used to confirm the surface architecture of IMS-LF-LCNPs. The results of cytotoxicity and 4,6-diamidino-2-phenylindole revealed that IMS-LF-LCNPs had the highest growth inhibition and significant apoptotic effects. Pharmacokinetics and biodistribution studies showed that IMS-LF-LCNPs have superior pharmacokinetic performance and targeted delivery compared to IMS-LCNPs and plain IMS, which was attributed to the targeting action of LF that targets the ASGPR in hepatic cells. Next, our in vivo experiment established that the HCC environment existed due to suppression of BAX, cyt c, BAD, e-NOS, and caspase (3 and 9) genes, which thus owed upstream expression of Bcl-xl, iNOS, and Bcl-2 genes. The excellent therapeutic potential of IMS-LF-LCNPs began the significant stimulation of caspase-mediated apoptotic signals accountable for its anti-HCC prospect. ¹H nuclear magnetic resonance (serum) metabolomics revealed that IMS-LF-LCNPs are capable of regulating the disturbed levels of metabolites linked to HCC triggered through N-nitrosodiethylamine. Therefore, IMS-LF-LCNPs are a potentially effective formulation against HCC.

Receptor Tyrosine Kinases in Osteosarcoma Treatment: Which Is the Key Target?

Recent clinical trials have shown several multi-target tyrosine kinase inhibitors (TKIs) to be effective in the treatment of osteosarcoma. However, these TKIs have a number of targets, and it is yet unclear which of these targets has a key role in osteosarcoma treatment. In this review, we first summarize the TKIs that were studied in clinical trials registered on ClinicalTrials.gov. Further, we compare and discuss the targets of these TKIs. We found that TKIs with promising therapeutic effect for osteosarcoma include apatinib, cabozantinib, lenvatinib, regorafenib, and sorafenib. The key targets for osteosarcoma treatment may include VEGFRs and RET. The receptor tyrosine kinases (RTKs) MET, IGF-1R, AXL, PDGFRs, KIT, and FGFRs might be relevant but unimportant targets for osteosarcoma treatment. Inhibition of one type of RTK for the treatment of osteosarcoma is not effective. It is necessary to inhibit several relevant RTKs simultaneously to achieve a breakthrough in osteosarcoma treatment. This review provides comprehensive information on TKI targets relevant in osteosarcoma treatment, and it will be useful for further research in this field.

Enhanced proliferation inhibition and apoptosis in glioma cells elicited by combination of irinotecan and imatinib

Glioma is a kind of lethal malignant tumor, and lacks efficient therapies. Combination therapy has been claimed to be a promising approach to combat cancer, due to its increased anti-cancer effects and reduced side effects. This study aimed to investigate the anti-cancer effect and mechanism of combining imatinib with irinotecan or its active metabolite 7-ethyl-10-hydroxycamptothecin (SN-38). First, we found that this drug combination exerted synergistic antitumor effects against glioma in vitro and in vivo. In addition, flow cytometry results proved that the SN-38-induced apoptosis was further enhanced by imatinib, and similar results were observed by determining the protein expression levels of apoptosis biomarkers. Interestingly, p53 expression was elevated by the SN-38 mono-treatment, and was not further increased after the co-treatment; besides, knockdown of p53 could only reduce the expression of cleaved-PARP partially, and weaken the enhanced proliferation inhibition induced by SN-38 plus imatinib, indicating that there might be other factors involved in the synergistic effects besides p53. Meanwhile, the markedly elevated p21 expression was observed only in the combination group, instead of the mono-treated groups. According to the results of p21 knockdown, we found that p21 was also required for the synergistic inhibitory effects. Moreover, we explored and ruled out the possibility of imatinib enhancing the sensitivity of irinotecan by inhibiting drug efflux pumps. Thus, our findings collectively suggest that combining irinotecan with imatinib could be a promising new strategy to fight against glioma.

Bone Metastasis: Current State of Play

Bone metastasis (BM) in cancer remains a critical issue because of its associated clinical and biological complications. Moreover, BM can alter the quality of life and survival rate of cancer patients. Growing evidence suggests that bones are a fertile ground for the development of metastasis through a "vicious circle" of bone resorption/formation and tumor growth. This review aims to outline the current major issues in the diagnosis and management of BM in the most common types of osteotropic cancers and describe the mechanisms and effects of BM. First, we discuss the incidence of BM through the following questions: Are we witnessing an increase in incidence, and are we now better equipped with modern imaging techniques? Is the advent of efficient bone resorption inhibitors affecting the bigger picture of BM management? Second, we discuss the potential effects of cancer progression and well-prescribed drugs, such as multitarget tyrosine kinase inhibitors, inhibitors of the mammalian target of rapamycin, and immune checkpoint inhibitors, on BM. Finally, we examine the duality of the effects of some therapies that may help in cancer treatment but may also contribute to further BM.

Genomic Complexity of Osteosarcoma and Its Implication for Preclinical and Clinical Targeted Therapies

Osteosarcoma is a genomically complex disease characterized by few recurrent single-nucleotide mutations or in-frame fusions. In contrast, structural alterations, including copy number changes, chromothripsis, kataegis, loss of heterozygosity (LOH), and other large-scale genomic alterations, are frequent and widespread across the osteosarcoma genome. These observed structural alterations lead to activation of oncogenes and loss of tumor suppressors which together contribute to oncogenesis. To date, few targeted therapies for osteosarcoma have been identified. It is likely that effectiveness of targeted therapies will vary greatly in subsets of tumors with distinct key driver events. Model systems which can recapitulate the genetic heterogeneity of this disease are needed to test this hypothesis. One possible approach is to use patient-derived xenograft (PDX) models characterized with regards to their similarity to the human tumor samples from which they were derived. Here we review evidence pointing to the genomic complexity of osteosarcoma and how this is reflected in available model systems. We also review the current state of preclinical testing for targeted therapies using these models.

Receptor Tyrosine Kinases in Osteosarcoma: 2019 Update

The primary conclusions of our 2014 contribution to this series were as follows: Multiple receptor tyrosine kinases (RTKs) likely contribute to aggressive phenotypes in osteosarcoma and, therefore, inhibition of multiple RTKs is likely necessary for successful clinical outcomes. Inhibition of multiple RTKs may also be useful to overcome resistance to inhibitors of individual RTKs as well as resistance to conventional chemotherapies. Different combinations of RTKs are likely important in individual patients. AXL, EPHB2, FGFR2, IGF1R, and RET were identified as promising therapeutic targets by our in vitro phosphoproteomic/siRNA screen of 42 RTKs in the highly metastatic LM7 and 143B human osteosarcoma cell lines. This chapter is intended to provide an update on these topics as well as the large number of osteosarcoma clinical studies of inhibitors of multiple tyrosine kinases (multi-TKIs) that were recently published.

CDC20 and its downstream genes: potential prognosis factors of osteosarcoma

BACKGROUND

We investigated the microarray data GSE42352 to identify genes that can be used as prognosis factors in osteosarcoma.

METHODS

Gene Ontology (GO) biological process analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of Cytoscape ClueGo were used in verifying the function of different genes. Realtime-PCR were used to confirm the microarray results. 83 patient samples were collected and underwent Kaplan-Meier survival analysis and multivariate analysis to predict the prospect of genes using as prognosis factors.

RESULTS

After analyzing the microarray data GSE42352, mitosis metaphase to anaphase-related genes CDC20, securin, cyclin A2 and cyclin B2 were found to be overexpressed in osteosarcoma cell lines. Kaplan-Meier survival analysis showed that overexpression of these genes can predict poor prognosis outcomes in osteosarcoma patients. Furthermore, any combination of the four genes seems to be more effective in predicting osteosarcoma outcomes than any of these genes alone.

CONCLUSIONS

CDC20 and its downstream substracts securin, cyclin A2 and cyclin B2 are good factors that can predict prognosis outcomes in osteosarcoma. Any two combination of these four genes are more effective to be used as osteosarcoma prognosis factors.

PDGF/PDGFR effects in osteosarcoma and the "add-on" strategy

New treatment options for advanced osteosarcoma have remained limited. The platelet-derived growth factor (PDGF)/platelet-derived growth factor receptor (PDGFR) pathway plays an important role in the development and metastasis of osteosarcoma, via either direct autocrine stimulation of tumor cells, or paracrine stimulation on tumor stromal cells. It promotes angiogenesis to overcome hypoxia in the tumor microenvironment, and modulates tumor interstitial fluid pressure to control the influx and efflux of other agents. Targeting the PDGF/PDGFR pathway is a promising therapeutic method to overcome drug resistance and improve patients' outcome in osteosarcoma. Further evidence is needed to define the detailed mechanism. Results from clinical trials using PDGF/PDGFR inhibitor as a single agent were disappointing, both in osteosarcoma and soft tissue sarcoma. However, when combined with other agents, named as "add-on" strategy, a synergistic antitumor effect has been confirmed in soft tissue sarcoma, and should be attempted in osteosarcoma.

Exploring targeted therapy of osteosarcoma using proteomics data

Despite multimodal therapeutic treatments of osteosarcoma (OS), some patients develop resistance to currently available regimens and eventually end up with recurrent or metastatic outcomes. Many attempts have been made to discover effective drugs for improving outcome; however, due to the heterogeneity of the disease, new therapeutic options have not yet been identified. This study aims to explore potential targeted therapy related to protein profiles of OS. In this review of proteomics studies, we extracted data on differentially expressed proteins (DEPs) from archived literature in PubMed and our in-house repository. The data were divided into three experimental groups, DEPs in 1) OS/OB: OS vs osteoblastic (OB) cells, 2) metastasis: metastatic vs non-metastatic sublines plus fresh tissues from primary OS with and without pulmonary metastasis, and 3) chemoresistance: spheroid (higher chemoresistance) vs monolayer cells plus fresh tissues from biopsies from good and poor responders. All up-regulated protein entities in the list of DEPs were sorted and cross-referenced with identifiers of targets of US Food and Drug Administration (FDA)-approved agents and chemical inhibitors. We found that many targets of FDA-approved antineoplastic agents, mainly a group of epigenetic regulators, kinases, and proteasomes, were highly expressed in OS cells. Additionally, some overexpressed proteins were targets of FDA-approved non-cancer drugs, including immunosuppressive and antiarrhythmic drugs. The resulting list of chemical agents showed that some transferase enzyme inhibitors might have anticancer activity. We also explored common targets of OS/OB and metastasis groups, including amidophosphoribosyltransferase (PPAT), l-lactate dehydrogenase B chain (LDHB), and pyruvate kinase M2 (PKM2) as well as the common target of all categories, cathepsin D (CTSD). This study demonstrates the benefits of a text mining approach to exploring therapeutic targets related to protein expression patterns. These results suggest possible repurposing of some FDA-approved medicines for the treatment of OS and using chemical inhibitors in drug screening tests.

Effects of the overexpression of IFITM5 and IFITM5 c.-14C>T mutation on human osteosarcoma cells

The present study aimed to investigate the effects of overexpression of interferon-induced transmembrane protein 5 (IFITM5) and IFITM5 c.-14C>T mutation on osteogenic differentiation, and the proliferation, migration and invasion of SaOS2 cells. SaOS2 cells were transfected with plasmids containing wild type IFITM5 (W) or IFITM5 containing the c.-14C>T mutation (MU). The mRNA and protein expression levels of IFITM5 in SaOS2 cells were respectively detected by reverse transcription quantitative polymerase chain reaction and western blotting. The proliferative, migratory and invasive ability of SaOS2 cells was also examined. In addition, the expression levels of osteogenic differentiation markers alkaline phosphatase (ALP), osteocalcin (OCN) and runt-related transcription factor 2 (Runx2) were detected. Mineralized nodules were detected by Alizarin Red S staining and were quantified by measuring absorbance. The mRNA and protein expression levels of IFITM5 were high in cells transfected with IFITM5 and IFITM5 c.-14C>T mutation, and were higher in cells transfected with IFITM5 c.-14C>T mutation. There was no difference in proliferation between the control group (C) and the W and MU groups. However, overexpression of IFITM5 and IFITM5 c.-14C>T mutation increased apoptotic rate, decreased invasive capacity, increased the expression of ALP, OCN and Runx2, and increased the number of mineralized nodules following osteogenic induction. In addition, compared with C and W groups, cells transfected with IFITM5 c.-14C>T mutation exhibited decreased migratory ability. In conclusion, overexpression of IFITM5 and IFITM5 c.-14C>T mutation promotes tumor cell apoptosis, inhibits tumor invasion and promotes osteogenic differentiation. These findings may provide a theoretical basis for the development of a novel treatment method that targets IFITM5, and provides a platform for the potential treatment of human osteosarcoma.

Noscapine targets EGFRp-Tyr1068 to suppress the proliferation and invasion of MG63 cells

Osteosarcoma, the most common primary malignant bone tumor, usually arises in the metaphysis of long bones. Amplification and mutation of the epidermal growth factor receptor (EGFR) gene represent signature genetic abnormalities encountered in osteosarcoma. Noscapine is a benzylisoquinoline alkaloid derived from the opium poppy Papaver somniferum. Recently several studies have suggested its anti-cancer effect in melanoma, ovarian cancer, gliomas, breast cancer, lung cancer, and colon cancer. However, the underlying molecular mechanism for its anti-cancer effect still remains unclear. In this paper, we found the mechanism of noscapine effectively suppressed proliferation and invasion of MG63 cell line by inhibiting the phosphorylation of EGFR and its downstream pathway.

Histology-Specific Uses of Tyrosine Kinase Inhibitors in Non-gastrointestinal Stromal Tumor Sarcomas

OPINION STATEMENT

Adult sarcomas, especially those with metastatic or unresectable disease, have limited treatment options. Traditional chemotherapeutic options have been limited by poor response rates in patients with advanced sarcomas. The important clinical question is whether the success of targeted therapy in GIST can be extended to other sarcomas and also if preclinical data describing targets across this heterogeneous group of cancers can be translated to clinical efficacy of known and upcoming target specific agents. Multi-targeted tyrosine kinase inhibitors (TKI) such as pazopanib, sorafenib, sunutinib, cediranib have shown benefits across various histologies of soft tissue sarcoma as well as bone sarcomas. The efficacy of imatinib in Dermatofibrosarcoma Protruberans; sunitinib and cediranib in alveolar soft part sarcoma; and sorafenib and imatinib in chordomas have provided a treatment option of these rare tumors where no effective options existed. TKIs are being tested in combination with chemotherapy as well as radiation to improve response. Although traditional RECIST criteria may not adequately reflect response to these targeted agents, the studies have shown promise for the efficacy of TKIs across the spectrum of sarcomas. The integration of biomarker studies with clinical trials may help further identify responders beyond that defined by histology. With the current data, TKIs are being used both as first-line treatment and beyond in non-GIST sarcomas.

Influence of ezrin-shRNA in combination with HSP70 on the apoptosis and proliferation of osteosarcoma cells

Ezrin and heat shock protein (HSP)70 have been reported to regulate cell apoptosis and tumor development of osteosarcoma. However, there has not been reported the synergy effect of knocking down ezrin and overexpressing HSP70. In the present study, two vectors, pGFP-V-RS-shRNA and pGFP-V-RS-shRNA-HSP70, were constructed and transfected into LM8 cells [denoted as small hairpin (sh)RNA group and dual group, respectively]. The apoptosis rates in these two transfected groups were significantly higher than those in the control group (empty vector) (P=0.036), while significantly lower proliferation rates were observed in these two groups (P=0.023). The cytotoxic T lymphocyte activity on target LM8 tumor cells in the dual group was significantly higher than in other groups, with cytotoxicity as high as 55.56±2.10%. Further studies revealed that the transfection of ezrin-shRNA/HSP70 also suppressed tumor formation in vivo in nude mice. A lower cluster of differentiation (CD)4/CD8 ratio was detected in the tumor formed by injecting cells in the dual group (P=0.006). Furthermore, the serum level of interleukin-4 in the dual group was significantly decreased, while the serum level of interferon-γ was significantly increased, compared with the other two groups (P=0.004). Simultaneously knocking down ezrin and overexpressing HSP70 promotes cellular apoptosis and suppresses the proliferation of osteosarcoma cells in vitro, and enhances the tumor killing effects of HSP70-induced immune killing.

Present Advances and Future Perspectives of Molecular Targeted Therapy for Osteosarcoma

Osteosarcoma (OS) is a bone cancer mostly occurring in pediatric population. Current treatment regime of surgery and intensive chemotherapy could cure about 60%-75% patients with primary osteosarcoma, however only 15% to 30% can be cured when pulmonary metastasis or relapse has taken place. Hence, novel precise OS-targeting therapies are being developed with the hope of addressing this issue. This review summarizes the current development of molecular mechanisms and targets for osteosarcoma. Therapies that target these mechanisms with updated information on clinical trials are also reviewed. Meanwhile, we further discuss novel therapeutic targets and OS-targeting drug delivery systems. In conclusion, a full insight in OS pathogenesis and OS-targeting strategies would help us explore novel targeted therapies for metastatic osteosarcoma.

Mesenchymal stem cells increase proliferation but do not change quiescent state of osteosarcoma cells: Potential implications according to the tumor resection status

Conventional therapy of primary bone tumors includes surgical excision with wide resection, which leads to physical and aesthetic defects. For reconstruction of bone and joints, allografts can be supplemented with mesenchymal stem cells (MSCs). Similarly, adipose tissue transfer (ATT) is supplemented with adipose-derived stem cells (ADSCs) to improve the efficient grafting in the correction of soft tissue defects. MSC-like cells may also be used in tumor-targeted cell therapy. However, MSC may have adverse effects on sarcoma development. In the present study, human ADSCs, MSCs and pre-osteoclasts were co-injected with human MNNG-HOS osteosarcoma cells in immunodeficient mice. ADSCs and MSCs, but not the osteoclast precursors, accelerated the local proliferation of MNNG-HOS osteosarcoma cells. However, the osteolysis and the metastasis process were not exacerbated by ADSCs, MSCs, or pre-osteoclasts. In vitro proliferation of MNNG-HOS and Saos-2 osteosarcoma cells was increased up to 2-fold in the presence of ADSC-conditioned medium. In contrast, ADSC-conditioned medium did not change the dormant, quiescent state of osteosarcoma cells cultured in oncospheres. Due to the enhancing effect of ADSCs/MSCs on in vivo/in vitro proliferation of osteosarcoma cells, MSCs may not be good candidates for osteosarcoma-targeted cell therapy. Although conditioned medium of ADSCs accelerated the cell cycle of proliferating osteosarcoma cells, it did not change the quiescent state of dormant osteosarcoma cells, indicating that ADSC-secreted factors may not be involved in the risk of local recurrence.

Targeting protein kinases to reverse multidrug resistance in sarcoma

Sarcomas are a group of cancers that arise from transformed cells of mesenchymal origin. They can be classified into over 50 subtypes, accounting for approximately 1% of adult and 15% of pediatric cancers. Wide surgical resection, radiotherapy, and chemotherapy are the most common treatments for the majority of sarcomas. Among these therapies, chemotherapy can palliate symptoms and prolong life for some sarcoma patients. However, sarcoma cells can have intrinsic or acquired resistance after treatment with chemotherapeutics drugs, leading to the development of multidrug resistance (MDR). MDR attenuates the efficacy of anticancer drugs and results in treatment failure for sarcomas. Therefore, overcoming MDR is an unmet need for sarcoma therapy. Certain protein kinases demonstrate aberrant expression and/or activity in sarcoma cells, which have been found to be involved in the regulation of sarcoma cell progression, such as cell cycle, apoptosis, and survival. Inhibiting these protein kinases may not only decrease the proliferation and growth of sarcoma cells, but also reverse their resistance to chemotherapeutic drugs to subsequently reduce the doses of anticancer drugs and decrease drug side-effects. The discovery of novel strategies targeting protein kinases opens a door to a new area of sarcoma research and provides insight into the mechanisms of MDR in chemotherapy. This review will focus on the recent studies in targeting protein kinase to reverse chemotherapeutic drug resistance in sarcoma.

EGFR is not a major driver for osteosarcoma cell growth in vitro but contributes to starvation and chemotherapy resistance

Background

Enhanced signalling via the epidermal growth factor receptor (EGFR) is a hallmark of multiple human carcinomas. However, in recent years data have accumulated that EGFR might also be hyperactivated in human sarcomas. Aim of this study was to investigate the influence of EGFR inhibition on cell viability and its interaction with chemotherapy response in osteosarcoma cell lines.

Methods

We have investigated a panel of human osteosarcoma cell lines regarding EGFR expression and downstream signalling. To test its potential applicability as therapeutic target, inhibition of EGFR by gefitinib was combined with osteosarcoma chemotherapeutics and cell viability, migration, and cell death assays were performed.

Results

Osteosarcoma cells expressed distinctly differing levels of functional EGFR reaching in some cases high amounts. Functionality of EGFR in osteosarcoma cells was proven by EGF-mediated activation of both MAPK and PI3K/AKT pathway (determined by phosphorylation of ERK1/2, AKT, S6, and GSK3β). The EGFR-specific inhibitor gefitinib blocked EGF-mediated downstream signal activation. At standard in vitro culture conditions, clinically achievable gefitinib doses demonstrated only limited cytotoxic activity, however, significantly reduced long-term colony formation and cell migration. In contrast, under serum-starvation conditions active gefitinib doses were distinctly reduced while EGF promoted starvation survival. Importantly, gefitinib significantly supported the anti-osteosarcoma activities of doxorubicin and methotrexate regarding cell survival and migratory potential.

Conclusion

Our data suggest that EGFR is not a major driver for osteosarcoma cell growth but contributes to starvation- and chemotherapy-induced stress survival. Consequently, combination approaches including EGFR inhibitors should be evaluated for treatment of high-grade osteosarcoma patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0251-5) contains supplementary material, which is available to authorized users.

Synergistic antiproliferative effect of imatinib and adriamycin in platelet-derived growth factor receptor-expressing osteosarcoma cells

Osteosarcoma (OS) is the most frequent primary solid malignant tumor of bone. Its prognosis remains poor in the substantial proportion of patients who do not respond to chemotherapy and novel therapeutic options are therefore needed. We previously established a mouse model that mimics the aggressive behavior of human OS. Enzyme-linked immunosorbent assay-based screening of such mouse tumor lysates identified platelet-derived growth factor–BB (PDGF-BB) as an abundant soluble factor, the gene for which was expressed dominantly in surrounding non-malignant cells of the tumor, whereas that for the cognate receptor (PDGF receptor β) was highly expressed in OS cells. Platelet-derived growth factor-BB induced activation of both MEK–ERK and phosphatidylinositol 3-kinase–protein kinase B signaling pathways and promoted survival in OS cells deprived of serum, and these effects were blocked by the PDGF receptor inhibitor imatinib. However, these actions of PDGF-BB and imatinib were mostly masked in the presence of serum. Whereas imatinib alone did not manifest an antitumor effect in mice harboring OS tumors, combined treatment with imatinib and adriamycin exerted a synergistic antiproliferative effect on OS cells in vivo. These results suggest that treatment of OS with imatinib is effective only when cell survival is dependent on PDGF signaling or when imatinib is combined with another therapeutic intervention that renders the tumor cells susceptible to imatinib action, such as by inducing cellular stress.

X609, a novel manassantin A derivative, exhibits antitumor activity in MG-63 human osteosarcoma cells in vitro and in vivo

Manassantin A has been well-established as an inhibitor of HIF-1. In the present study, a new manasantin A derivative, X609, with decreased stereochemical complexity, rendering it amenable to a simplified synthesis scheme, was synthesized and was found to increase HIF-1 inhibitory activity. X609 exhibited antiproliferative activity in a broad spectrum of tumor cell lines, via HIF-1-dependent mechanisms. X609 may induce apoptosis in MG-63 cells through activation of the mitochondrial pathway. Oral administration of X609 significantly inhibited the growth of human osteosarcomas implanted into nude mice. In light of the results of the present study, it may be possible to develop X609 for use as a novel antitumor agent, which targets human osteosarcoma.

Apoptosis prediction via inhibition of AKT signaling pathway by neogrifolin

Neogrifolin, a natural biologically active substance isolated from the edible bodies of the mushroom Albatrellus confluens, has been shown to possess several pharmacological properties. No studies were investigated against osteosarcoma cancer. Hence, in this study, we investigated the apoptosis-inducing effects and the mechanisms of neogrifolin on human osteosarcoma cells. Our results demonstrated that neogrifolin induced concentration- and time-dependent suppression of proliferation. Further, induction of apoptosis in U2OS and MG63 osteosarcoma cell lines were also observed. Neogrifolin induced the release of cytochrome c accompanied by activation of caspase-9, caspase-3 and cleavage of poly (ADP-ribose) polymerase (PARP). In addition, z-VAD-fmk, a universal inhibitor of caspases, prevented caspase-3 activation and PARP cleavage and inhibited neogrifolin-induced cell growth inhibition. Furthermore, neogrifolin treatment resulted in a reduction of phosphorylated AKT level, FOXO transcription factor, and glycogen synthase kinase 3 (GSK3). Knockdown of GSK3 with siRNA inhibited the apoptotic effects of neogrifolin. On the other hand, neogrifolin treatment also down-regulated the expression of the inhibitor of apoptosis protein (IAP) in both osteosarcoma cells. Collectively, our results suggested that neogrifolin is a potential candidate for osteosarcoma.

HSP70 desensitizes osteosarcoma cells to baicalein and protects cells from undergoing apoptosis

Baicalein is a new drug that has shown promising anti-cancer effects against a broad spectrum of tumors. However, the potential effect on osteosarcoma cells and the mechanisms involved are still largely unknown. Resistance to chemotherapy remains a major obstacle in cancer therapy. Therefore, the aim of the present study was to investigate the anti-tumor effect of baicalein on human osteosarcoma cancer cells and the molecular mechanism involved, as well as identify possible mechanisms of drug resistance. Our results revealed that baicalein-induced apoptosis in osteosarcoma cells was via a mitochondrial pathway involving both caspase-dependent and independent mechanisms. Notably, baicalein treatment upregulated the expression of HSP70, which partially prevented human osteosarcoma cells from undergoing apoptosis. Moreover, it was revealed that HSP70 expression decreased the sensitivity of osteosarcoma cells to baicalein via activation of PI3K/AKT and MAPK/ERK pathways. These results suggest that targeting HSP70-mediated drug resistance, in combination with chemotherapy drugs, may provide novel therapeutic opportunities.

Receptor tyrosine kinases: Characterisation, mechanism of action and therapeutic interests for bone cancers

Bone cancers are characterised by the development of tumour cells in bone sites, associated with a dysregulation of their environment. In the last two decades, numerous therapeutic strategies have been developed to target the cancer cells or tumour niche. As the crosstalk between these two entities is tightly controlled by the release of polypeptide mediators activating signalling pathways through several receptor tyrosine kinases (RTKs), RTK inhibitors have been designed. These inhibitors have shown exciting clinical impacts, such as imatinib mesylate, which has become a reference treatment for chronic myeloid leukaemia and gastrointestinal tumours. The present review gives an overview of the main molecular and functional characteristics of RTKs, and focuses on the clinical applications that are envisaged and already assessed for the treatment of bone sarcomas and bone metastases.