Expression of Snail2 in long bone osteosarcomas correlates with tumour malignancy

DLX2 promotes osteosarcoma epithelial-mesenchymal transition and doxorubicin resistance by enhancing HOXC8-CDH2 axis

Metastasis and doxorubicin resistance are challenges in the clinical diagnosis and treatment of osteosarcoma, the mechanisms underlying these phenomena remain unclear. In this study, we found that DLX2 is highly expressed in metastatic osteosarcoma and is closely related to clinical prognosis. Knockdown of DLX2 inhibited tumor proliferation and migration in vitro and inhibited tumor growth in vivo. Mechanistically, we found that DLX2 enhanced the repression of CDH2 transcription by binding to HOXC8, thereby promoting the epithelial-mesenchymal transition in osteosarcoma cells. Through subsequent exploration, we found that targeting DLX2/HOXC8 signaling significantly restores the sensitivity of osteosarcoma cells to doxorubicin. In conclusion, our findings demonstrate that DLX2 may enhance the transcriptional regulation of CDH2 through interacting with HOXC8, which in turn promotes epithelial-mesenchymal transition and doxorubicin resistance in osteosarcoma. These findings hold great potential for clinical application and may guide the development of novel targeted therapies for osteosarcoma.

Does PAX7 and NKX2.2 immunoreactivity in Ewing sarcoma have prognostic significance?

Ewing sarcoma (ES) is an aggressive neoplasm with variable morphology. It has no specific immunoprofile or molecular signature. Neither CD99, NKX2.2 nor PAX7 immunoreactivity alone is completely specific, although diagnostic specificity improves when combined. The purpose of the present study was to investigate the immunohistochemical (IHC) expression of PAX7 in a large series of genetically confirmed ES. Existing results for CD99 and NKX2.2 immunoexpression, morphological findings and molecular studies (fusion gene subtypes) were retrieved from a previous study. Survival analyses were performed in cases with available clinical follow-up. PAX7 was positive in 95.5% of ES with diffuse staining (> 50%) in all positive cases and moderate or strong intensity for most cases. Nineteen ES displayed both PAX7 and CD99 immunoreactivity but lacked NKX2.2 immunoexpression. No relationships could be found between PAX7 expression and the histological types or ES gene fusion subtypes. Univariant/multivariate analysis showed that lack of PAX7 and/or NKX2.2 immunoexpression constitute independent poor prognostic factors for progression free survival (PFS) and overall survival (OS). In conclusion, IHC for CD99, NKX2.2, and PAX7 may be useful in daily practice for ES diagnosis, particularly in hospitals lacking facilities for molecular studies. In addition, the combination of strong CD99 membranous positivity and nuclear PAX7 and NKX2.2 immunoreactivity seems to be very reliable for ES diagnosis when supported by a corroborating histomorphologic and clinical picture. Although PAX7 is not entirely specific for ES, it seems to have a more extensive and strong nuclear immunoreactivity than NKX2.2 expression, even in tumors with decalcification artifact. Considering the prognostically significant data herein reported, we strongly recommend validation in prospective ES series that include localized and disseminated tumors.

TGF‑β inhibitor RepSox suppresses osteosarcoma via the JNK/Smad3 signaling pathway

Osteosarcoma (OS) is the most common malignant bone tumor and the long-term survival rates remain unsatisfactory. Transforming growth factor-β (TGF-β) has been revealed to play a crucial role in OS progression, and RepSox is an effective TGF-β inhibitor. In the present study, the effect of RepSox on the proliferation of the OS cell lines (HOS and 143B) was detected. The results revealed that RepSox effectively inhibited the proliferation of OS cells by inducing S-phase arrest and apoptosis. Moreover, the inhibitory effect of RepSox on cell migration and invasion was confirmed by wound-healing and Transwell assays. Furthermore, western blotting revealed that the protein levels of molecules associated with the epithelial-mesenchymal transition (EMT) phenotype, including E-cadherin, N-cadherin, Vimentin, matrix metalloproteinase (MMP)-2 and MMP-9, were reduced by RepSox treatment. Concurrently, it was also revealed that the JNK and Smad3 signaling pathway was inhibited. Our in vivo findings using a xenograft model also revealed that RepSox markedly inhibited the growth of tumors. In general, our data demonstrated that RepSox suppressed OS proliferation, EMT and promoted apoptosis by inhibiting the JNK/Smad3 signaling pathway. Thus, RepSox may be a potential anti-OS drug.

Overexpression of the Ubiquitin Specific Proteases USP43, USP41, USP27x and USP6 in Osteosarcoma Cell Lines: Inhibition of Osteosarcoma Tumor Growth and Lung Metastasis Development by the USP Antagonist PR619

Osteosarcoma (OS) is the most common malignant bone tumor in children and teenagers. In many cases, such as poor response to treatment or the presence of metastases at diagnosis, the survival rate of patients remains very low. Although in the literature, more and more studies are emerging on the role of Ubiquitin-Specific Proteases (USPs) in the development of many cancers, few data exist regarding OS. In this context, RNA-sequencing analysis of OS cells and mesenchymal stem cells differentiated or not differentiated into osteoblasts reveals increased expression of four USPs in OS tumor cells: USP6, USP27x, USP41 and USP43. Tissue microarray analysis of patient biopsies demonstrates the nucleic and/or cytoplasmic expression of these four USPs at the protein level. Interestingly, Kaplan–Meyer analysis shows that the expression of two USPs, USP6 and USP41, is correlated with patient survival. In vivo experiments using a preclinical OS model, finally demonstrate that PR619, a USP inhibitor able to enhance protein ubiquitination in OS cell lines, reduces primary OS tumor growth and the development of lung metastases. In this context, in vitro experiments show that PR619 decreases the viability of OS cells, mainly by inducing a caspase3/7-dependent cell apoptosis. Overall, these results demonstrate the relevance of targeting USPs in OS.

Research models and mesenchymal/epithelial plasticity of osteosarcoma

Most osteosarcomas (OSs) develop from mesenchymal cells at the bone with abnormal growth in young patients. OS has an annual incidence of 3.4 per million people and a 60-70% 5-year surviving rate. About 20% of OS patients have metastasis at diagnosis, and only 27% of patients with metastatic OS survive longer than 5 years. Mutation of tumor suppressors RB1, TP53, REQL4 and INK4a and/or deregulation of PI3K/mTOR, TGFβ, RANKL/NF-κB and IGF pathways have been linked to OS development. However, the agents targeting these pathways have yielded disappointing clinical outcomes. Surgery and chemotherapy remain the main treatments of OS. Recurrent and metastatic OSs are commonly resistant to these therapies. Spontaneous canine models, carcinogen-induced rodent models, transgenic mouse models, human patient-derived xenograft models, and cell lines from animal and human OSs have been developed for studying the initiation, growth and progression of OS and testing candidate drugs of OS. The cell plasticity regulated by epithelial-to-mesenchymal transition transcription factors (EMT-TFs) such as TWIST1, SNAIL, SLUG, ZEB1 and ZEB2 plays an important role in maintenance of the mesenchymal status and promotion of cell invasion and metastasis of OS cells. Multiple microRNAs including miR-30/9/23b/29c/194/200, proteins including SYT-SSX1/2 fusion proteins and OVOL2, and other factors that inhibit AMF/PGI and LRP5 can suppress either the expression or activity of EMT-TFs to increase epithelial features and inhibit OS metastasis. Further understanding of the molecular mechanisms that regulate OS cell plasticity should provide potential targets and therapeutic strategies for improving OS treatment.

Molecular Mechanisms of Canine Osteosarcoma Metastasis

Osteosarcoma (OSA) represents the most common bone tumor in dogs. The malignancy is highly aggressive, and most of the dogs die due to metastasis, especially to the lungs. The metastatic process is complex and consists of several main steps. Assessment of the molecular mechanisms of metastasis requires in vitro and especially in vivo studies for a full evaluation of the process. The molecular and biological resemblance of canine OSA to its human counterpart enables the utilization of dogs as a spontaneous model of this disease in humans. The aim of the present review article is to summarize the knowledge of genes and proteins, including p63, signal transducer and activator of transcription 3 (STAT3), Snail2, ezrin, phosphorylated ezrin-radixin-moesin (p-ERM), hepatocyte growth factor-scatter factor (HGF-SF), epidermal growth factor receptor (EGFR), miR-9, and miR-34a, that are proven, by in vitro and/or in vivo studies, to be potentially involved in the metastatic cascade of canine OSA. The determination of molecular targets of metastatic disease may enhance the development of new therapeutic strategies.

Theabrownin inhibits the cytoskeleton‑dependent cell cycle, migration and invasion of human osteosarcoma cells through NF‑κB pathway‑related mechanisms

Considering the high metastatic potential of osteosarcoma, not only pro-apoptosis, but also anti-metastasis is important for anti-osteosarcoma therapy. Previously, the authors reported the pro-apoptotic and tumor-inhibitory effects of theabrownin (TB) on osteosarcoma cells; however, its effects on the metastasis-related migration and invasion of osteosarcoma cells remain unknown. The present study conducted RNA sequencing (RNA-seq) on xenograft zebrafish samples and performed in vitro experiments, including RT-qPCR, cell viability analysis, clone formation assay, cell cycle analysis, immunofluorescence, cell migration assay, cell invasion assay, wound healing assay and western blot (WB) analysis to evaluate the anti-metastatic effects and mechanism of TB against osteosarcoma cells. The RNA-seq data revealed that TB significantly downregulated the expression of genes involved in the microtubule bundle formation of U2OS cells, which was verified by RT-qPCR. The cell viability and clone formation data indicated that TB significantly inhibited U2OS cell viability and colony numbers. The results of cell cycle analysis revealed the blocked cell cycle progression of U2OS by TB. The immunofluorescent data revealed an evident cytoskeleton-inhibitory effect of TB against the microfilament and microtubule formation of U2OS cells. The results of cell migration and invasion demonstrated that TB significantly inhibited U2OS cell migration and invasion. The results of WB analysis revealed that TB significantly regulated key molecules of epithelial-mesenchymal transition [EMT; e.g., E-cadherin, vimentin, Snail-1, Slug and zinc finger E-box-binding homeobox 1 (ZEB-1)] and those of the nuclear factor (NF)-κB pathway (e.g., NF-κB, phospho-IKKα and phospho-IKKβ), indicating that NF-κB pathway-related EMT suppression may mediate the mechanisms underlying the anti-migratory and anti-invasive effects of TB against osteosarcoma. To the best of our knowledge, this is the first study on the inhibitory effects and mechanisms of TB on the cytoskeleton-dependent cell cycle, migration and invasion of human osteosarcoma cells. The findings presented herein suggest that TB may be a promising anti-metastatic candidate for anti-osteosarcoma therapy.

Long noncoding RNA RHPN1-AS1 exerts pro-oncogenic actions in osteosarcoma by functioning as a molecular sponge of miR-506 to positively regulate SNAI2 expression

The long noncoding RNA, RHPN1 antisense RNA 1 (RHPN1-AS1), performs important regulatory actions in the progression of many human cancers. In this study, we aimed to analyze RHPN1-AS1 expression in osteosarcoma (OS) and to assess the influence of RHPN1-AS1 knockdown on the malignant behavior of OS cells. The molecular mechanisms by which RHPN1-AS1 affects the oncogenicity of OS were explored too. The expression of RHPN1-AS1 in OS was measured by RT-qPCR. The effects of the RHPN1-AS1 silencing in OS cells were studied both in vitro (in a Cell Counting Kit-8 assay, apoptosis analysis, and Transwell migration and invasion assays) and in vivo (by means of tumor xenografts in nude mice). Herein, RHPN1-AS1 expression was found to be significantly upregulated in OS tissues and cell lines. The elevated expression of RHPN1-AS1 closely correlated with the tumor size, TNM stage, distal metastasis and shorter overall survival in patients with OS. The depletion of RHPN1-AS1 restrained OS cell proliferation, migration, and invasion, and exerted proapoptotic effects in vitro. Furthermore, the knockdown of RHPN1-AS1 effectively reduced the tumor growth of OS cells in vivo. As for the mechanism, RHPN1-AS1 increased snail family zinc finger 2 (SNAI2 also known as SNAIL2) expression by acting as a competing endogenous RNA of miR-506. Notably, increasing the amount of miR-506 partially reversed the effects of the RHPN1-AS1 downregulation on OS cells. In conclusion, RHPN1-AS1 contributes to the malignancy of OS cells in vitro and in vivo, largely via upregulation of the miR-506-SNAI2 axis output.

New Insights about the Wnt/β-Catenin Signaling Pathway in Primary Bone Tumors and Their Microenvironment: A Promising Target to Develop Therapeutic Strategies?

Osteosarcoma and Ewing sarcoma are the most common malignant primary bone tumors mainly occurring in children, adolescents and young adults. Current standard therapy includes multidrug chemotherapy and/or radiation specifically for Ewing sarcoma, associated with tumor resection. However, patient survival has not evolved for the past decade and remains closely related to the response of tumor cells to chemotherapy, reaching around 75% at 5 years for patients with localized forms of osteosarcoma or Ewing sarcoma but less than 30% in metastatic diseases and patients resistant to initial chemotherapy. Despite Ewing sarcoma being characterized by specific EWSR1-ETS gene fusions resulting in oncogenic transcription factors, currently, no targeted therapy could be implemented. It seems even more difficult to develop a targeted therapeutic strategy in osteosarcoma which is characterized by high complexity and heterogeneity in genomic alterations. Nevertheless, the common point between these different bone tumors is their ability to deregulate bone homeostasis and remodeling and divert them to their benefit. Therefore, targeting different actors of the bone tumor microenvironment has been hypothesized to develop new therapeutic strategies. In this context, it is well known that the Wnt/β-catenin signaling pathway plays a key role in cancer development, including osteosarcoma and Ewing sarcoma as well as in bone remodeling. Moreover, recent studies highlight the implication of the Wnt/β-catenin pathway in angiogenesis and immuno-surveillance, two key mechanisms involved in metastatic dissemination. This review focuses on the role played by this signaling pathway in the development of primary bone tumors and the modulation of their specific microenvironment.

New challenges in integrated diagnosis by imaging and osteo-immunology in bone lesions

INTRODUCTION

High-resolution imaging is the gold standard to measure the functional and biological features of bone lesions. Imaging markers have allowed the characterization both of tumour heterogeneity and metabolic data. Besides, ongoing studies are evaluating a combined use of 'imaging markers', such as SUVs, MATV, TLG, ADC from PET and MRI techniques respectively, and several 'biomarkers' spanning from chemokine immune-modulators, such as PD-1, RANK/RANKL, CXCR4/CXCL12 to transcription factors, such as TP53, RB1, MDM2, RUNX family, EZH2, YY1, MAD2. Osteoimmunology may improve diagnosis and prognosis leading to precision medicine in bone lesion treatment. Areas covered: We investigated modalities (molecular and imaging approach) useful to identify bone lesions deriving both from primary bone tumours and from osteotropic tumours, which have a higher incidence, prevalence and prognosis. Here, we summarized the recent advances in imaging techniques and osteoimmunology biomarkers which could play a pivotal role in personalized treatment. Expert commentary: Although imaging and molecular integration could allow both early diagnosis and stratification of cancer prognosis, large scale clinical trials will be necessary to translate pilot studies in the current clinical setting.

ABBREVIATIONS

ADC: apparent diffusion coefficient; ALCAM: Activated Leukocyte Cell Adhesion Molecule; ALP: Alkaline phosphatases; BC: Breast cancer; BSAP: B-Cell Lineage Specific Activator; BSAP: bone-specific alkaline phosphatase; BSP: bone sialoprotein; CRIP1: cysteine-rich intestinal protein 1; CD44: cluster of differentiation 44; CT: computed tomography; CXCL12: C-X-C motif ligand 12; CXCR4: C-X-C C-X-C chemokine receptor type 4; CTLA-4: Cytotoxic T-lymphocyte antigen 4; CTX-1: C-terminal end of the telopeptide of type I collagen; DC: dendritic cell; DWI: Diffusion-weighted MR image; EMT: mesenchymal transition; ET-1: endothelin-1; FDA: Food and Drug Administration; FDG: ¹⁸F-2-fluoro-2-deoxy-D-glucose; FGF: fibroblast growth factor; FOXC2: forkhead box protein C2: HK-2: hexokinase-2; ICTP: carboxyterminal cross-linked telopeptide of type I collagen; IGF-1R: Insulin Like Growth Factor 1 Receptor; ILC: innate lymphocytes cells; LC: lung cancer; IL-1: interleukin-1; LYVE1: lymphatic vessel endothelial hyaluronic acid receptor 1; MAD2: mitotic arrest deficient 2; MATV: metabolically active tumour volume; M-CSF: macrophage colony stimulating factor; MM: multiple myeloma; MIP1a: macrophage inflammatory protein 1a; MSC: mesenchymal stem cell; MRI: magnetic resonance imaging; PC: prostate cancer; NRP2: neuropilin 2; OPG: osteoprotogerin; PDGF: platelet-derived growth factor; PD-1: Programmed Cell Death 1; PET: positron emission tomography; PINP: procollagen type I N propeptide; PROX1: prospero homeobox protein 1; PSA: Prostate-specific antigen; PTH: parathyroid hormone; RANK: Receptor activator of NF-kB ligand; RECK: Reversion-inducing-cysteine-rich protein; SEMAs: semaphorins; SPECT: single photon computed tomography; SUV: standard uptake value; TLG: total lesion glycolysis; TP53: tumour protein 53; VCAM-1: vascular endothelial molecule-1; VOI: volume of interest; YY1: Yin Yang 1.

Chalcone Derivatives 4'-Amino-1-Naphthyl-Chalcone (D14) and 4'-Amino-4-Methyl-1-Naphthyl-Chalcone (D15) Suppress Migration and Invasion of Osteosarcoma Cells Mediated by p53 Regulating EMT-Related Genes

Osteosarcoma (OS) is a primary malignant bone tumor that mainly affects children, adolescents, and young adults. The inhibition of metastasis is a main strategy of OS therapy since the development of metastatic disease due to drug resistance remains the most important cause of death from this cancer. Considering the severe side effects of current OS chemotherapy, the identification of anti-metastatic drugs with reduced toxicity is of great interest. Chalcones are polyphenols with a basic structure consisting of an α-, β-unsaturated carbonyl system linking two aryl rings. These compounds exhibit anticancer activity against a variety of tumor cell lines through multiple mechanisms, including the regulation of the tumor-suppressor protein p53 and its target genes. An important process regulated by p53 is epithelial-mesenchymal transition (EMT), which facilitates tumor metastasis by conferring migratory and invasive properties to cancer cells. The activation of p53 can revert EMT and reduce migration and invasion. This study aimed to examine the inhibitory effects of two 4′-aminochalcones on the migration/invasion of the U2OS (p53+/+) and SAOS-2 (p53−/−) OS cell lines as well as the underlying molecular mechanisms. Cell viability was examined by MTT assay. Transwell assays were used to evaluate the migratory and invasive ability of the cells. The two 4′-aminochalcones showed low capacity to inhibit the viability of OS cells independent of p53 status, but preferentially suppressed the migration of U2OS cells and of a SAOS-2 cell line expressing p53. Invasion was strongly inhibited by both chalcones independent of p53 status. RT-PCR, zymography, and Western blot were used to study the expression of matrix metalloproteinases and EMT markers after treatment with the chalcones. The results indicated that the 4′-aminochalcone-induced antimigratory and anti-invasive effects are potentially associated with the inhibition of extracellular matrix (ECM) enzymatic degradation in OS cells and with the modulation of EMT genes. These effects probably result from the induced increase of p53 protein expression by the two chalcones. In conclusion, chalcones D14 and D15 have potential anti-metastatic activity mediated by p53 that can be exploited for OS treatment.

The Kraken Wakes: induced EMT as a driver of tumour aggression and poor outcome

Epithelial mesenchymal transition (EMT) describes the shift of cells from an epithelial form to a contact independent, migratory, mesenchymal form. In cancer the change is linked to invasion and metastasis. Tumour conditions, including hypoxia, acidosis and a range of treatments can trigger EMT, which is implicated in the subsequent development of resistance to those same treatments. Consequently, the degree to which EMT occurs may underpin the entire course of tumour progression and treatment response in a patient. In this review we look past the protective effect of EMT against the initial treatment, to the role of the mesenchymal state, once triggered, in promoting disease growth, spread and future treatment insensitivity. In patients a correlation was found between the propensity of a treatment to induce EMT and failure of that treatment to provide a survival benefit, implicating EMT induction in accelerated tumour progression after treatment cessation. Looking to the mechanisms driving this detrimental effect; increased proliferation, suppressed apoptosis, stem cell induction, augmented angiogenesis, enhanced metastatic dissemination, and immune tolerance, can all result from treatment-induced EMT and could worsen outcome. Evidence also suggests EMT induction with earlier therapies attenuates benefits of later treatments. Looking beyond epithelial tumours, de-differentiation also has therapy-attenuating effects and reversal thereof may yield similar rewards. A range of potential therapies are in development that may address the diverse mechanisms and molecular control systems involved in EMT-induced accelerated progression. Considering the broad reaching effects of mesenchymal shift identified, successful deployment of such treatments could substantially improve patient outcomes.

Transforming Growth Factor-β Signaling Plays a Pivotal Role in the Interplay Between Osteosarcoma Cells and Their Microenvironment

Osteosarcomas are the most frequent form of primary bone tumors and mainly affect children, adolescents, and young adults. Despite encouraging progress in therapeutic management, including the advent of multidrug chemotherapy, the survival rates have remained unchanged for more than four decades: 75% at 5 years for localized disease, but two groups of patients are still at high risk: metastatic at diagnosis (overall survival around 40% at 5 years) and/or poor responders to chemotherapy (20% at 5 years). Because these tumors are classified as “complex genomic,” it is extremely difficult to determine the signaling pathways that might be targeted by specific therapies. A hypothesis has thus emerged, stating that the particular microenvironment of these tumors may interfere with the tumor cells that promote chemoresistance and the dissemination of metastases. The stroma is composed of a large number of cell types (immune cells, endothelial cells, mesenchymal stromal cells, etc.) which secrete growth factors, such as transforming growth factor-β (TGF-β), which favors the development of primary tumors and dissemination of metastases by constituting a permissive niche at primary and distant sites. Rather than targeting the tumor cells themselves, which are very heterogeneous in osteosarcoma, the hypothesis is instead to target the key actors secreted in the microenvironment, such as TGF-βs, which play a part in tumor progression. In the last decade, numerous studies have shown that overexpression of TGF-β is a hallmark of many cancers, including primary bone tumors. In this context, TGF-β signaling has emerged as a crucial factor in the cross talk between tumor cells and stroma cells in poor-prognosis cancers. Secretion of TGF-β by tumor cells or stroma cells can effectively act in a paracrine manner to regulate the phenotype and functions of the microenvironment to stimulate protumorigenic microenvironmental changes. TGF-β can thus exert its protumorigenic function in primary bone tumors by promoting angiogenesis, bone remodeling and cell migration, and by inhibiting immunosurveillance. This review focuses on the involvement of TGF-β signaling in primary bone tumor development, and the related therapeutic options that may be possible for these tumors.

FKBP14 overexpression contributes to osteosarcoma carcinogenesis and indicates poor survival outcome

The FK506-binding protein 14 (FKBP14) is a subfamily of immunophilins, has been implicated in various biochemical processes. However, its effects on the primary malignant bone tumor, osteosarcoma, are unclear. Here, we reported that FKBP14 may be an oncogene as it overexpressed in osteosarcoma tissues and cell lines, and FKBP14 expression was correlated with metastases, recurrence, tumor maximum diameter and poor survival time. FKBP14 was associated with the biological pathways including cell cycle, apoptosis and metastasis. Furthermore, we detected FKBP14 knockdown induced cell cycle arrest, apoptosis, invasion and adhesion in vitro. FKBP14 knockdown decreased the protein levels of PCNA, CDK1 and CCNB1 that promotes cell cycle, increased Bax, caspase-3 and caspase-7 protein involved in promoting cell apoptosis, and increased KIF4A expression as well as decreased SMC4 and TMEM33 proteins that contribute to cell invasion and adhesion. In addition, FKBP14 knockdown also caused a significant inhibition in tumor growth in vivo. Then, we found that the protein RhoA was identified as a binding partner of FKBP14. Taken together, FKBP14 may act as an oncogene in osteosarcoma via suppressing apoptosis and promoting invasion and adhesion in osteosarcoma carcinogenesis. FKBP14 may be a prognostic factor and potential target for osteosarcoma treatment.

ZIC2 promotes viability and invasion of human osteosarcoma cells by suppressing SHIP2 expression and activating PI3K/AKT pathways

Osteosarcoma is a malignant tumor of the skeletal system. The zinc finger transcription factor ZIC2 has been reported to be highly expressed in human cancers. The present study evaluated the effects of ZIC2 and the possible underlying mechanisms in the human osteosarcoma cells. The expression levels of ZIC2 in human fetal osteoblastic cell line (hFOB1.19), osteosarcoma cell lines (U-2OS, SaoS2, and MG63), normal bone tissue, and osteosarcoma tumor were analyzed by Western blot, and real-time quantitative RT-PCR (qRT-PCR). Osteosarcoma cells with either overexpressed ZIC2 or suppressed ZIC2 were analyzed to determine cell viability, colony formation, and cell invasion. The expressions of SHIP2 and PI3K/AKT signal pathway-related proteins were analyzed by Western blot and qRT-PCR. We first showed that ZIC2 is highly expressed in osteosarcoma cells and tissues. Then we demonstrated that overexpression of ZIC2 promoted viability, migration, and invasion of osteosarcoma cells, whereas suppression of ZIC2 showed opposite effects. Furthermore, SHIP2 expression was negatively regulated by ZIC2. Importantly, ZIC2 overexpression activated the PI3K/AKT signal pathway; however, overexpressed SHIP2 inhibited these effects. Lastly, we showed that activation of the PI3K/AKT signal pathway is essential for the effects of ZIC2 on osteosarcoma cells, as the effects of ZIC2 on the osteosarcoma cells were reversed by a PI3K/AKT inhibitor. Overall, ZIC2 is highly expressed in osteosarcoma cells and tissues, and its overexpression promotes viability, invasion of osteosarcoma cells via SHIP2 suppression, and PI3K/AKT activation. Thus, ZIC2 can be considered as a novel drug target for osteosarcoma management.

Immunohistochemical Validation of Spontaneously Arising Canine Osteosarcoma as a Model for Human Osteosarcoma

Osteosarcoma (OS) originates from bone-forming mesenchymal cells and represents one of the primary bone tumours. It is the most common primary bone tumour in dogs and man. The characterization of an appropriate natural disease animal model to study human OS is essential to elucidate the pathogenesis of the disease. This study aimed to validate canine OS as a model for the human disease by evaluating immunohistochemically the expression of markers known to be important in human OS. The immunohistochemical panel included vimentin, alkaline phosphatase (ALP), desmin, S100, neuron-specific enolase (NSE), runt-related transcription factor 2 (Runx2) and bone morphogenetic protein 4 (BMP4). Immunohistochemistry was conducted on formalin-fixed, paraffin wax-embedded tissue sections from 59 dogs with confirmed primary OS. Vimentin, ALP, Runx2 and BMP4 were highly expressed by all tumours, while desmin, S100 and NSE were expressed variably. The findings were similar to those described previously for human OS and suggest that canine OS may represent a useful model for the study of the human disease.

Biomarkers of Osteosarcoma, Chondrosarcoma, and Ewing Sarcoma

Osteosarcoma is the most frequent malignant bone neoplasm, followed by chondrosarcoma and Ewing sarcoma. The diagnosis of bone neoplasms is generally made through histological evaluation of a biopsy. Clinical and radiological features are also important in aiding diagnosis and to complete the staging of bone cancer. In addition to these, there are several non-specific serological or specific molecular markers for bone neoplasms. In bone tumors, molecular markers increase the accuracy of the diagnosis and assist in subtyping bone tumors. Here, we review these markers and discuss their role in the diagnosis and prognosis of the three most frequent malignant bone neoplasms, namely osteosarcoma, chondrosarcoma, and Ewing sarcoma.

Platelets Inhibit Migration of Canine Osteosarcoma Cells

The interaction between platelets and tumour cells is important for tumour growth and metastasis. Thrombocytopenia or antiplatelet treatment negatively impact on cancer metastasis, demonstrating potentially important roles for platelets in tumour progression. To our knowledge, there is no information regarding the role of platelets in cancer progression in dogs. This study was designed to test whether canine platelets affected the migratory behaviour of three canine osteosarcoma cell lines and to give insights of molecular mechanisms. Intact platelets, platelet lysate and platelet releasate inhibited the migration of canine osteosarcoma cell lines. Addition of blood leucocytes to the platelet samples did not alter the inhibitory effect on migration. Platelet treatment also significantly downregulated the transcriptional levels of SNAI2 and TWIST1 genes. The interaction between canine platelets or molecules released during platelet activation and these tumour cell lines inhibits their migration, which suggests that canine platelets might antagonize metastasis of canine osteosarcoma. This effect is probably due to, at least in part, downregulation of genes related to epithelial-mesenchymal transition.

SPAG9 is overexpressed in osteosarcoma, and regulates cell proliferation and invasion through regulation of JunD

Sperm-associated antigen 9 (SPAG9) is a recently characterized oncoprotein that is considered to be involved in several forms of malignant tumor. However, its biological function and expression pattern in human osteosarcoma have not yet been elucidated. In the present study, SPAG9 expression was analyzed in 58 cases of human osteosarcoma by immunohistochemistry. The results demonstrated that SPAG9 was overexpressed in 63.8% (37/58) of osteosarcoma tissues, while normal bone tissues exhibited negative SPAG9 expression. SPAG9 small interfering RNA was employed in the U2OS cell line, which has high endogenous expression, and SPAG9 transfection was performed in the MG63 cell line, which has low endogenous expression. MTT and Matrigel invasion assays demonstrated that SPAG-9-knockdown significantly reduced U2OS cell invasion and proliferation, while SPAG9 transfection enhanced MG63 cell proliferation and invasion. Furthermore, it was observed that SPAG9 positively regulated cyclin D1, phosphorylated-c-Jun NH2-terminal kinase (JNK) and JunD expression. Treatment with the JNK inhibitor, SP600125, abolished the upregulatory effect of SPAG9 on JunD. Taken together, the present study identified SPAG9 as a critical oncoprotein involved in osteosarcoma proliferation and invasion, possibly functioning through JNK-JunD signaling.

Significance of MTA1 in the molecular characterization of osteosarcoma

Osteosarcoma is the most common malignant bone tumor in children and characterized by aggressive biologic behavior of metastatic propensity to the lung. Change of treatment paradigm brings survival benefit; however, 5-year survival rate is still low in patients having metastastatic foci at diagnosis for a few decades. Metastasis-associated protein (MTA) family is a group of ubiquitously expressed coregulators, which influences on tumor invasiveness or metastasis. MTA1 has been investigated in various cancers including osteosarcoma, and its overexpression is associated with high-risk features of cancers. In this review, we described various molecular studies of osteosarcoma, especially associated with MTA1.

CIP2A is overexpressed in osteosarcoma and regulates cell proliferation and invasion

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a newly characterized oncoprotein involved in a variety of malignant tumors. However, its expression pattern and biological functions in osteosarcoma remain unclear. In the present study, CIP2A expression was analyzed in 51 human osteosarcoma specimens using immunohistochemistry. CIP2A siRNA was used in the MG-63 cell line, and the effect of CIP2A depletion on cell proliferation and invasion was evaluated. We found that CIP2A was overexpressed in 76.5 % (39/51) of osteosarcoma tissues, while normal bone tissues showed negative CIP2A expression. In addition, the positive rate of CIP2A expression was higher in stage IIB osteosarcoma than stage IIA cases. Knockdown of the CIP2A expression significantly reduced osteosarcoma cell proliferation and invasion, with decreased c-Myc expression and p-AKT expression. CIP2A depletion also facilitated apoptosis and inhibited MMP9 mRNA expression. Taken together, our data identified CIP2A as a critical oncoprotein involved in cell proliferation and invasion, which could serve as a therapeutic target in osteosarcoma.

EMT transcription factors: implication in osteosarcoma

The primary malignant bone tumor, osteosarcoma, is a deadly disorder. Its etiology is complex, and treatment is mostly obscure. The transcription factors (TFs) involved in epithelial to mesenchymal transition (EMT) have significant role in osteosarcoma. A number of evidence suggests that overexpression of EMT-TFs, such as Twist, Snails and Zebs, is involved in complex pathogenesis of osteosarcoma. Recent research studies have showed some extent of promise in osteosarcoma treatment by targeting these EMT-TFs. However, success in research on osteosarcoma-EMT-TFs axis is just in primary stage, and a long way to go. Targeting Twist, Snail or Zeb by specific molecules or chemotherapeutic agents may provide a new dimension in osteosarcoma treatment by controlling metastasis.

Snail2 promotes osteosarcoma cell motility through remodelling of the actin cytoskeleton and regulates tumor development

The function of Snail2 in mesenchymal tumors is, to date unknown. Using knockdown and overexpression studies, we show that Snail2 regulates migration and invasion of osteosarcoma cells. Knockdown resulted in significantly decreased motility, remodelling of the actin cytoskeleton, and loss of cellular protrusions. Over-expression increased motility, formation of actin-rich cellular protrusions, and altered expression of some non-canonical Wnt pathway components whilst decreasing expression of the adhesion molecule OB-cadherin. Unexpectedly, knockdown also resulted in significantly smaller tumors in an in vivo CAM assay. Therefore Snail2 may be a potential therapeutic target for clinical intervention of osteosarcoma.

Epithelial cell adhesion molecules and epithelial mesenchymal transition (EMT) markers in Ewing's sarcoma family of tumors (ESFTs). Do they offer any prognostic significance?

Epithelial marker and adhesion molecule expression has been reported in Ewing's sarcoma family of tumors (ESFTs), although the prognostic significance has not been assessed systematically. We performed immunohistochemical analysis of epithelial cell adhesion molecule and epithelial mesenchymal transition markers on 415 genetically confirmed ESFTs. Survival analyses were performed in 217 patients. The atypical histological subtype expressed a high proportion of the epithelial markers compared with conventional and PNET variants. We observed that expression of desmoplakin (p < 0.001) and PI3K (p = 0.003) was higher in disseminated than in localized disease. Multivariate analysis showed that desmoplakin and pGSK3β constitute independent good prognostic factors for progression free survival (PFS), while ZO-1 and Snail represent independent good prognostic factors for overall survival (OS). In contrast, CK8/18 represents an independent poor prognostic factor for OS and the radiotherapy treatment group demonstrated an independent poor prognostic factor for PFS and OS. Although the expression of pan-cytokeratin has been previously highlighted in a significant proportion of ESFT, its expression did not reveal prognostic significance in the present series. Considering the results of prognostic analysis herein reported, we strongly recommend a prospective validation of at least the immunomarkers with prognostic significance (desmoplakin, ZO-1, CK8/18, pGSK3β, and Snail) in prospective series that include localized and disseminated tumors.

Immunohistochemical investigation of cell cycle and apoptosis regulators (survivin, β-catenin, p53, caspase 3) in canine appendicular osteosarcoma

Background

Osteosarcoma (OSA) represents the most common canine primary bone tumour. Despite several pathways have been investigated so far, few molecules have been identified as prognostic tools or potential therapeutic targets, and there is still the need to find out molecular pathways with specific influence over OSA progression to facilitate earlier prognosis and treatment.

Aims of the present study were to evaluate the immunohistochemical pattern and levels of expression of a panel of molecules (survivin, β-catenin, caspase 3 -inactive and active forms- and p53) involved in cell cycle and apoptosis regulation in canine OSA samples, known to be of interest in the study also of human OSA, and to detect specific relations among them and with histological tumour grade, disease free interval (DFI) and overall survival (OS).

Results

Nuclear β-catenin immunostaining was detected in normal osteoblasts adjacent to the tumour, and in 47% of the cases. Cytoplasmic and/or membranous immunostaining were also observed. Nuclear survivin and p53 positive cells were found in all cases. Moderate/high cytoplasmic β-catenin expression (≥10% positive cells) was significantly associated with the development of metastasis (P = 0.014); moderate/high nuclear p53 expression (≥10% positive cells) was significantly associated with moderate/high histological grade (P = 0.017) and shorter OS (P = 0.049). Moderate/high nuclear survivin expression (≥15% positive cells) showed a tendency toward a longer OS (P = 0,088).

Conclusions

The present results confirmed p53 as negative prognostic marker, while suggested survivin as a potential positive prognostic indicator, rather than indicative of a poor prognosis. The detection of nuclear β-catenin immunostaining in normal osteoblasts and the absent/low expression in most of the OSAs, suggested that this pathway could not play a major role in oncogenic transformation of canine osteoblasts. Further studies are needed to confirm these hypotheses.

Prognostic factors in canine appendicular osteosarcoma - a meta-analysis

Background

Appendicular osteosarcoma is the most common malignant primary canine bone tumor. When treated by amputation or tumor removal alone, median survival times (MST) do not exceed 5 months, with the majority of dogs suffering from metastatic disease. This period can be extended with adequate local intervention and adjuvant chemotherapy, which has become common practice. Several prognostic factors have been reported in many different studies, e.g. age, breed, weight, sex, neuter status, location of tumor, serum alkaline phosphatase (SALP), bone alkaline phosphatase (BALP), infection, percentage of bone length affected, histological grade or histological subtype of tumor. Most of these factors are, however, only reported as confounding factors in larger studies. Insight in truly significant prognostic factors at time of diagnosis may contribute to tailoring adjuvant therapy for individual dogs suffering from osteosarcoma. The objective of this study was to systematically review the prognostic factors that are described for canine appendicular osteosarcoma and validate their scientific importance.

Results

A literature review was performed on selected studies and eligible data were extracted. Meta-analyses were done for two of the three selected possible prognostic factors (SALP and location), looking at both survival time (ST) and disease free interval (DFI). The third factor (age) was studied in a qualitative manner. Both elevated SALP level and the (proximal) humerus as location of the primary tumor are significant negative prognostic factors for both ST and DFI in dogs with appendicular osteosarcoma. Increasing age was associated with shorter ST and DFI, however, was not statistically significant because information of this factor was available in only a limited number of papers.

Conclusions

Elevated SALP and proximal humeral location are significant negative prognosticators for canine osteosarcoma.

Possible role of Snail expression as a prognostic factor in canine mammary neoplasia

Epithelial cells adhere tightly to each other by cell-to-cell adhesion and through the basement membrane barrier to prohibit movement. In carcinomas, neoplastic epithelial cells lose their epithelial characteristics and acquire a mesenchymal phenotype during the epithelial-mesenchymal transition (EMT) for invasion and metastasis. The aim of this study was to identify Snail expression and examine the role of Snail protein in canine mammary tumour progression. Immunohistochemical expression of Snail, E-cadherin, oestrogen receptor, human epidermal growth factor receptor-2, cytokeratin 14 and p63 was analyzed in 54 samples of canine mammary epithelial tumours (11 adenomas and 43 carcinomas). Expression of mRNA encoding Snail was evaluated in seven samples (one normal mammary gland, two adenomas and four carcinomas) by reverse transcriptase-polymerase chain reaction. Snail mRNA was detected in all samples. Snail expression correlated significantly with histological type, grade and lymphatic invasion. However, there was no association between Snail expression and molecular subtype and between Snail expression and that of E-cadherin. Snail, a hallmark of EMT, might play an important role in invasion and metastasis of canine mammary carcinomas.