Japanese orthopaedic association (JOA) clinical practice guidelines on the management of malignant bone tumors - Secondary publication

BACKGROUND

In Japan, there are currently no general guidelines for the treatment of primary malignant bone tumors. Therefore, the Japanese Orthopaedic Association established a committee to develop guidelines for the appropriate diagnosis and treatment of primary malignant bone tumors for medical professionals in clinical practice.

METHODS

The guidelines were developed in accordance with "Minds Clinical Practice Guideline Development Handbook 2014″ and "Minds Clinical Practice Guideline Development Manual 2017". The Japanese Orthopaedic Association's Bone and Soft Tissue Tumor Committee established guideline development and systematic review committees, drawing members from orthopedic specialists leading the diagnosis and treatment of bone and soft tissue tumors. Pediatricians, radiologists, and diagnostic pathologists were added to both committees because of the importance of multidisciplinary treatment. Based on the diagnosis and treatment algorithm for primary malignant bone tumors, important decision-making points were selected, and clinical questions (CQ) were determined. The strength of recommendation was rated on two levels and the strength of evidence was rated on four levels. The recommendations published were selected based on agreement by 70% or more of the voters.

RESULTS

The guideline development committee examined the important clinical issues in the clinical algorithm and selected 22 CQs. The systematic review committee reviewed the evidence concerning each CQ and a clinical value judgment was added by experts. Eventually, 25 questions were published and the text of each recommendation was determined.

CONCLUSION

Since primary malignant bone tumors are rare, there is a dearth of strong evidence based on randomized controlled trials, and recommendations cannot be applied to all the patients. In clinical practice, appropriate treatment of patients with primary malignant bone tumors should be based on the histopathological diagnosis and degree of progression of each case, using these guidelines as a reference.

Therapeutic potential of tyrosine-protein kinase MET in osteosarcoma

Osteosarcoma, the most prevalent primary bone tumor in children and young adults, can often be successfully treated with standard chemotherapy and surgery when diagnosed at an early stage. However, patients presenting with metastases face significant challenges in achieving a cure. Despite advancements in classical therapies over the past few decades, clinical outcomes for osteosarcoma have not substantially improved. Recently, there has been increased understanding of the biology of osteosarcoma, leading to the identification of new therapeutic targets. One such target is MET, a tyrosine kinase receptor for Hepatocyte Growth Factor (HGF) encoded by the MET gene. In vitro and in vivo studies have demonstrated that the HGF/MET pathway plays a crucial role in cancer growth, invasion, metastasis, and drug resistance across various cancers. Clinical trials targeting this pathway are already underway for lung cancer and hepatocellular carcinoma. Moreover, MET has also been implicated in promoting osteosarcoma progression. This review summarizes 3 decades' worth of research on MET's involvement in osteosarcoma and further explores its potential as a therapeutic target for patients with this disease.

Construction of a prognostic risk score model based on the ARHGAP family to predict the survival of osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most common primary malignancy of bone tumors. More and more ARHGAP family genes have been confirmed are to the occurrence, development, and invasion of tumors. However, its significance in osteosarcoma remains unclear. In this study, we aimed to identify the relationship between ARHGAP family genes and prognosis in patients with OS.

METHODS

OS samples were retrieved from the TCGA and GEO databases. We then performed LASSO regression analysis and multivariate COX regression analysis to select ARHGAP family genes to construct a risk prognosis model. We then validated this prognostic model. We utilized ESTIMATE and CIBERSORT algorithms to calculate the stroma and immune scores of samples, as well as the proportions of tumor infiltrating immune cells (TICs). Finally, we conducted in vivo and in vitro experiments to investigate the effect of ARHGAP28 on osteosarcoma.

RESULTS

We selected five genes to construct a risk prognosis model. Patients were divided into high- and low-risk groups and the survival time of the high-risk group was lower than that of the low-risk group. The high-risk group in the prognosis model constructed had relatively poor immune function. GSEA and ssGSEA showed that the low-risk group had abundant immune pathway infiltration. The overexpression of ARHGAP28 can inhibit the proliferation, migration, and invasion of osteosarcoma cells and tumor growth in mice, and IHC showed that overexpression of ARHGAP28 could inhibit the proliferation of tumor cells.

CONCLUSION

We constructed a risk prognostic model based on five ARHGAP family genes, which can predict the overall survival of patients with osteosarcoma, to better assist us in clinical decision-making and individualized treatment.

Circ_SIPA1L1 Promotes Osteosarcoma Progression Via miR-379-5p/MAP3K9 Axis

Background: Osteosarcoma (OS) is a common malignant bone tumor. Circular RNAs (circRNAs) exert important roles in the pathogenesis of human cancers, including OS. In this study, the authors focused on the role and mechanism of circRNA signal-induced proliferation-associated 1 like 1 (circ_SIPA1L1) in OS. Methods: The enrichment of SIPA1L1, circ_SIPA1L1, microRNA-379-5p (miR-379-5p), and mitogen-activated protein kinase kinase kinase 9 (MAP3K9) was assessed by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The colony formation capacity was assessed through colony formation assay. Transwell assays were used to detect the migration and invasion abilities. Western blot assay was used to measure the expression of metastasis-related proteins and MAP3K9. The target interactions between the genes in circ_SIPA1L1/miR-379-5p/MAP3K9 axis were predicted by StarBase and confirmed by dual-luciferase reporter assay. The in vivo role of circ_SIPA1L1 was verified by murine xenograft assay. Results: Circ_SIPA1L1 abundance was aberrantly elevated in OS tissues and cell lines. Circ_SIPA1L1 accelerated the proliferation and metastasis abilities of OS cells. Circ_SIPA1L1 promoted the malignant behaviors of OS cells through elevating MAP3K9 level. MiR-379-5p directly bound to circ_SIPA1L1 and MAP3K9. MiR-379-5p interference rescued the abilities of proliferation and metastasis in OS cells, which were suppressed by the silencing of circ_SIPA1L1. Circ_SIPA1L1 promoted the development of OS via miR-379-5p/MAP3K9 in vivo. Conclusion: Circ_SIPA1L1 promoted the progression of OS via miR-379-5p/MAP3K9 axis.

Advances in the Biological Functions and Mechanisms of miRNAs in the Development of Osteosarcoma

Osteosarcoma is one of the most common primary malignant bone tumors, mainly occurring in children and adolescents, and is characterized by high morbidity and poor prognosis. MicroRNAs, a class of noncoding RNAs consisting of 19 to 25 nucleotides, are involved in cell proliferation, invasion, metastasis, and apoptosis to regulate the development and progression of osteosarcoma. Studies have found that microRNAs are closely related to the diagnosis, treatment, and prognosis of osteosarcoma patients and have an important role in improving drug resistance in osteosarcoma. This paper reviews the role of microRNAs in the pathogenesis of osteosarcoma and their clinical value, aiming to provide a new research direction for diagnosing and treating osteosarcoma and achieving a better prognosis.

Osteosarcoma of the Pelvis: Clinical Presentation and Overall Survival

Introduction

Osteosarcoma is the most common sarcoma of bone. Pelvic osteosarcoma presents a significant therapeutic challenge due to potential late symptom onset, metastatic dissemination at diagnosis, and inherent difficulties of wide surgical resection secondary to the complex and critical anatomy of the pelvis. The rates of survival are well reported for osteosarcoma of the appendicular skeleton, but specific details regarding presentation and survival are less known for osteosarcoma of the pelvis.

Methods

The Surveillance, Epidemiology, and End Results (SEER) program was queried for primary osteosarcoma of the bony pelvis from 2004 to 2015. Cases with Collaborative Staging variables (available after 2004) were analyzed by grade, histologic subtype, surgical intervention, tumor size, tumor extension, and presence of metastasis at diagnosis. The 2-, 5-, and 10-year survival rates were assessed with respect to these variables. The SEER database was then queried for age, tumor size, surgical intervention, metastasis at time of presentation, and survivorship data for patients with primary osteosarcoma of the upper extremity, lower extremity, vertebrae, thorax, and face/skull, and rates for all anatomic locations were then compared to patients with primary pelvic osteosarcoma.

Results

A total of 292 cases of pelvic osteosarcoma were identified from 2004 to 2015 within the database, representing 9.8% of cases among all surveyed primary sites. The most common histologic subtype was osteoblastic osteosarcoma (69.9%), followed by chondroblastic osteosarcoma (22.3%). The majority of cases were high-grade tumors (94.3%), of size >8 cm (72.0%), and with extension beyond the originating bone (74.0%). For the entire pelvic osteosarcoma group, the 2-, 5-, 10-year survival rates were 45.6%, 26.5%, and 21.4%, respectively, which were the poorest among surveyed anatomic sites. The 5-year overall survival was an abysmal 5.3% for patients with metastatic disease at diagnosis, and 37.0% for non-metastatic pelvic osteosarcoma treated with surgery and chemotherapy. When compared to other locations, pelvic osteosarcoma had higher rates of metastatic disease at presentation (33.5%), larger median tumor size (11.0 cm), and older median age at diagnosis (47.5 years). While over 85% of patients with tumors at the extremities received surgery, only 47.4% of pelvic osteosarcomas in this cohort received surgical resection—likely influenced by larger tumor size, sacral involvement, frequency of metastasis, older age, or delayed referral to a sarcoma center.

Conclusion

This study clarifies presenting features and clinical outcomes of pelvic osteosarcomas, which often present with large, high-grade tumors with extracompartmental extension, high likelihood of metastatic disease at diagnosis, and a potential limited ability to be addressed surgically. The survival rates of primary osteosarcoma of the pelvis are poor and are lower than osteosarcomas from other anatomic locations. While acknowledging the influence of metastasis, tumor characteristics, and advanced age on the decision to undergo surgical excision of a pelvic osteosarcoma, the rates of surgical resection are low and highlight the importance of understanding appropriate conditions for oncologic resection of pelvic sarcomas.

hsa_circ_0000006 induces tumorigenesis through miR-361-3p targeting immunoglobulin-like domains protein 1 (LRIG1) in osteosarcoma

Background

Osteosarcoma (OS) is considered to be the most highly prevalent bone tumor. In the progression of different human cancers, the role of circular RNAs (circRNAs) has been extensively studied. Microarray analysis has indicated that hsa_circ_0000006 expression was lower in OS, but the mechanism of hsa_circ_0000006 in regulating the progression of OS remains elusive.

Methods

The expression of cancer-related genes at the transcriptional and translational levels was assessed by RT-qPCR and western blotting (WB). Colony formation and Cell Counting Kit-8 (CCK-8) assays were used to evaluate the proliferative potential of cells. The transwell assay was used to examine the invasive and migratory potential of cells. Furthermore, dual-luciferase reporter (DLR) and RNA pull-down assays were performed for the validation of the targeting sites of hsa_circ_0000006, miR-361-3p, and the 3'-untranslated region (3'-UTR) of immunoglobulin-like domains protein 1 (LRIG1) mRNA. Moreover, the protein levels of epithelial-to-mesenchymal transition (EMT) markers were analyzed by WB.

Results

The expression of hsa_circ_0000006 and LRIG1 were found to be down-regulated in OS tissues and cells, while miR-361-3p was up-regulated. Knockdown of hsa_circ_0000006 promoted the progression and development of OS, as well as EMT. Furthermore, hsa_circ_0000006 was revealed as a sponge of miR-361-3p, which negatively regulates miR-361-3p expression. LRIG1 was found to be an miR-361-3p target. In OS cells, the LRIG1 expression level was decreased, with elevated expression of miR-361-3p. Advanced studies demonstrated that hsa_circ_0000006 regulates LRIG1 expression through sponging miR-361-3p, then promotes the tumorigenesis of OS.

Conclusions

hsa_circ_0000006 is associated with the progression and development of OS through miR-361-3p by target LRIG1, which is a significant biomarker and effective therapeutic target for patients with OS.

Hematopoietic cell kinase enhances osteosarcoma development via the MEK/ERK pathway

Osteosarcoma (OS) is a sarcoma with high rates of pulmonary metastases and mortality. The mechanisms underlying tumour generation and development in OS are not well‐understood. Haematopoietic cell kinase (HCK), a vital member of the Src family of kinase proteins, plays crucial roles in cancer progression and may act as an anticancer target; however, the mechanism by which HCK enhances OS development remains unexplored. Therefore, we investigated the role of HCK in OS development in vitro and in vivo. Downregulation of HCK attenuated OS cell proliferation, migration and invasion and increased OS cell apoptosis, whereas overexpression of HCK enhanced these processes. Mechanistically, HCK expression enhanced OS tumorigenesis via the mitogen‐activated protein kinase (MEK)/extracellular signal‐regulated kinase (ERK) pathway; HCK upregulation increased the phosphorylation of MEK and ERK and promoted epithelial‐mesenchymal transition, with a reduction in E‐cadherin in vitro. Furthermore, HCK downregulation decreased the tumour volume and weight in mice transplanted with OS cells. In conclusion, HCK plays a crucial role in OS tumorigenesis, progression and metastasis via the MEK/ERK pathway, suggesting that HCK is a potential target for developing treatments for OS.

Manganese-doped gold core mesoporous silica particles as a nanoplatform for dual-modality imaging and chemo-chemodynamic combination osteosarcoma therapy

In this study, an effective and facile strategy is reported to construct a multifunctional nanoplatform by in situ doping metal manganese on gold core mesoporous silica nanoparticles (Au@MMSN). After further modification of alendronate (Ald) on Au@MMSN, the obtained Au@MMSN-Ald efficiently integrates bone targeted chemo-chemodynamic combination therapy and dual-modality computed tomography/magnetic resonance (CT/MR) imaging into a single platform. In particular, Au@MMSN-Ald exhibits excellent tumor microenvironment responsive drug release efficiency. The doxorubicin hydrochloride (DOX) loaded Au@MMSN-Ald (DOX@Au@MMSN-Ald) is demonstrated with excellent targeted ability toward osteosarcoma. Accordingly, in a specific tumor microenvironment, DOX@Au@MMSN-Ald also displays outstanding combined efficiency for killing cancer cells in vitro and suppressing the osteosarcoma growth in vivo. Benefiting from the Au nanoparticles confined in the core and manganese ions released from the shell, CT and MR dual-modality imaging were performed to verify the effective accumulation of Au@MMSN-Ald at the tumor site. Overall, the constructed DOX@Au@MMSN-Ald nanoparticles integrated imaging guide, responsive drug release and combination therapy, which may provide some insight for further biomedical applications in efficient osteosarcoma therapy.

Circular RNA circ_0002137 regulated the progression of osteosarcoma through regulating miR-433-3p/ IGF1R axis

Current clinical treatment targeting osteosarcoma (OS) are limited for OS patients with pulmonary metastasis or relapse, which led to high mortality (70%‐85%) for advanced osteosarcoma patients. Although ongoing efforts have been made to illustrate the mechanisms of tumorigenesis and progression in OS; however, it was far for us to learn a comprehensive molecular mechanism implies in OS development. In our study, we implicated a circRNA hsa_circ_0002137, which was higher expressed in osteosarcoma tumours compared with paracancerous tissue. The dysregulated expression pattern was also found in osteosarcoma cell lines. The role of circ_0002137 was explored via down‐ or up‐regulated experiments. It was proved that down‐regulation of circ_0002137 suppressed the progress of OS, including cell invasion, cell cycle and cell apoptosis. Furthermore, the correlation between circ_0002137 and miR‐433‐3p was predicted using bioinformatic tools and verified utilizing RNA pull‐down assay and luciferase reporter assay. Interestingly, we found that the inhibitory effect of circ_0002137 on OS was dependent of insulin‐like growth factor‐1 receptor (IGF1R). In conclusion, it was demonstrated that circ_0002137 could restrain the progression of OS through regulating miR‐433‐3p/IGF1R axis, providing a comprehensive landscape of circ_0002137 in the generation and development of OS.

Nomograms to predict lung metastasis probability and lung metastasis subgroup survival in malignant bone tumors

The aim of this study was to construct and validate nomograms for predicting lung metastasis and lung metastasis subgroup overall survival in malignant primary osseous neoplasms. Least absolute shrinkage and selection operator, logistic and Cox analyses were used to identify risk factors for lung metastasis in malignant primary osseous neoplasms and prognostic factors for overall survival in the lung metastasis subgroup. Further, nomograms were established and validated. A total of 3184 patients were collected. Variables including age, histology type, American Joint Committee on Cancer T and N stage, other site metastasis, tumor extension and surgery were extracted for the nomograms. The authors found that nomograms could provide an effective approach for clinicians to identify patients with a high risk of lung metastasis in malignant primary osseous neoplasms and perform a personalized overall survival evaluation for the lung metastasis subgroup.

LncRNA GSEC promotes the proliferation, migration and invasion by sponging miR-588/ EIF5A2 axis in osteosarcoma

BACKGROUND

Long noncoding RNAs (LncRNAs) show dysregulation in a variety of cancers. However, the function and specific mechanism of LncRNA GSEC in the progression of osteosarcoma remain mostly unknown. In this study, we sought to elucidate the role and mechanism of LncRNA GSEC in the occurrence and progression of osteosarcoma.

METHODS

we examined the expression of LncRNA GSEC in osteosarcoma cell lines by quantitative real time PCR. In vitro experiments, including transwell assays, cck8 assays, and flow cytometry analysis have biologically demonstrated the effect of LncRNA GSEC on the proliferation and migration of osteosarcoma cell lines. Furthermore, the regulation of miR-588 by LncRNA GSEC was determined by luciferase reporter assay and quantitative real time PCR. What's more, subcutaneous tumor formation was performed in nude mice to monitor the growth of the tumor in vivo.

RESULTS

We found that the expression of LncRNA GSEC was up-regulated in osteosarcoma cell lines. Overexpression of LncRNA GSEC promoted the proliferating and migratory capacity, and inhibited the apoptosis of osteosarcoma cells. Conversely, knockdown of LncRNA GSEC resulted in the opposite effect. Mechanistically, we identified LncRNA GSEC functioned as the sponge of miR-588, thus inhibiting the miR-588/EIF5A2 signal pathway. In addition, the expression of miR-588 was negatively correlated with LncRNA GSEC, and the effect by silencing or overexpressing LncRNA GSEC could be rescued by the introduction of miR-588 mimics or inhibitors, respectively.

CONCLUSIONS

In summary, this study shows that LncRNA GSEC promotes the proliferation and invasion of OS through the regulation of miR-588/EIF5A2 pathway, which might provide a new strategy for the treatment of osteosarcoma in the future.

TUSC8 inhibits the development of osteosarcoma by sponging miR‑197‑3p and targeting EHD2

Osteosarcoma (OS) is one of the most common malignant bone tumours and generally occurs in children and adolescents. Increasing evidence has demonstrated that dysregulated long non-coding RNAs (lncRNAs) play crucial roles in the progression of various human neoplasms. Among these, tumour suppressor candidate 8 (TUSC8) is a novel lncRNA and has been reported to function as a tumour suppressor in cervical cancer. However, the exact role of TUSC8 in OS remains largely unknown. In the present study, it was observed that TUSC8 was markedly downregulated in OS tissues and cell lines. Functional experiments demonstrated that the overexpression of TUSC8 significantly suppressed the proliferation, migration, invasion and epithelial-mesenchymal transition (EMT), whereas it accelerated the apoptosis of OS cells. Mechanistically, TUSC8 served as a sponge for miR-197-3p, and EH-domain containing 2 (EHD2) was identified as a downstream target molecule of miR-197-3p. Further investigations indicated that EHD2 knockdown significantly reversed the effects on OS cellular processes induced by TUSC8 overexpression. On the whole, these findings indicate that TUSC8 functions as a competing endogenous RNA (ceRNA) to suppress OS cell growth and EMT via the miR-197-3p/EHD2 axis. TUSC8 may thus function as a potential therapeutic target in OS treatment.

Long Noncoding RNA HNF1A-AS1 Regulates Osteosarcoma Advancement Through Modulating the miR-32-5p/HMGB1 Axis

Background: Osteosarcoma (OS) is a primary malignant tumor in children and adolescents. Long noncoding RNA HNF1A antisense RNA 1 (HNF1A-AS1) is connected with OS development. However, there are few reports on the role and mechanism of HNF1A-AS1 in OS. Materials and Methods: Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to assess the expression of HNF1A-AS1, miR-32-5p, and high-mobility group protein B1 (HMGB1). Western blot analysis was performed to detect the protein level of HMGB1. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation, transwell, or flow cytometer assays were applied to determine the proliferation, migration, invasion, and apoptosis of OS cells. The interaction between HNF1A-AS1 and miR-32-5p or HMGB1 was predicted by the starBase database and confirmed by dual-luciferase reporter assay. Enzyme-linked immunosorbent assay was employed to analyze levels of HMGB1 in the OS cell supernatant. Results: HNF1A-AS1 and HMGB1 were upregulated, while miR-32-5p was downregulated, in OS tissues and cells. Functionally, HNF1A-AS1 depletion induced apoptosis and impeded proliferation, migration, and invasion of OS cells. Interestingly, HNF1A-AS1 bound to miR-32-5p to regulate the expression of HMGB1. Furthermore, miR-32-5p knockdown overturned the effects of HNF1A-AS1 knockdown on apoptosis, proliferation, migration, and invasion of OS cells. In addition, the effects of HNF1A-AS1 silencing on the malignant behaviors of OS cells were reserved by HMGB1 overexpression. In addition, HNF1A-AS1 regulated the HMGB1 level in the OS cell supernatant through the miR-32-5p/HMGB1 axis. Conclusion: Downregulation of HNF1A-AS1 blocked OS progression through the miR-32-5p/HMGB1 axis, which provides a possible target and prognostic biomarker for treatment of OS.

Locally Controlled Release of Methotrexate and Alendronate by Thermo-Sensitive Hydrogels for Synergistic Inhibition of Osteosarcoma Progression

Osteosarcoma (OS) is a serious primary bone malignant tumor that can easily affect children and adolescents. Chemotherapy is one of the important and feasible clinical treatment strategies for the treatment of OS at present, which is severely limited due to insufficient retention time, poor penetration ability, and serious side effects of current anti-tumor drug preparations. In this work, a novel injectable thermo-sensitive hydrogel (mPEG₄₅-PLV₁₉) loaded with methotrexate and alendronate, and the sustained release at the tumor site synergistically inhibited the progression of OS. The mPEG₄₅-PLV₁₉ shows excellent physical and chemical properties. Compared with other treatment groups, the in vivo treatment of gel+ methotrexate + alendronate effectively inhibited the growth of tumor. More importantly, it significantly reduced bone destruction and lung metastasis caused by OS. Therefore, this injectable thermo-sensitive hydrogel drug delivery system has broad prospects for OS chemotherapy.

Selective Activation of ZAK β Expression by 3-Hydroxy-2-Phenylchromone Inhibits Human Osteosarcoma Cells and Triggers Apoptosis via JNK Activation

Although various advancements in radical surgery and neoadjuvant chemotherapy have been developed in treating osteosarcoma (OS), their clinical prognosis remains poor. A synthetic chemical compound, 3-hydroxylflavone, that is reported to regulate ROS production is known to inhibit human bone osteosarcoma cells. However, its role and mechanism in human OS cells remains unclear. In this study, we have determined the potential of 3-Hydroxy-2-phenylchromone (3-HF) against OS using human osteosarcoma (HOS) cells. Our previous studies showed that Zipper sterile-alpha-motif kinase (ZAK), a kinase member of the MAP3K family, was involved in various cellular events such as cell proliferation and cell apoptosis, and encoded two transcriptional variants, ZAKα and β. In this study, we show that 3-HF induces the expression of ZAK and thereby enhances cellular apoptosis. Using gain of function and loss of function studies, we have demonstrated that ZAK activation by 3-HF in OS cells is confined to a ZAKβ form that presumably plays a leading role in triggering ZAKα expression, resulting in an aggravated cancer apoptosis. Our results also validate ZAKβ as the predominant form of ZAK to drive the anticancer mechanism in HOS cells.

Afatinib is active in osteosarcoma in osteosarcoma cell lines

PURPOSE

Osteosarcoma is the most common bone tumor, mainly affecting adolescents and young adults, and metastatic disease has poor outcomes with a dismal overall survival. Currently, chemotherapy is the standard of care with limited results, finding that new therapies could improve these outcomes. Preclinical and clinical studies have suggested a possible important role of ErbB pathway aberrations in osteosarcoma etiology. The present study shows the effect of afatinib, an irreversible ErbB family blocker in osteosarcoma cell lines.

METHODS

Within a panel of human osteosarcoma cell lines, we addressed cell viability assay using afatinib at increasing concentrations. Motility was measured in wound-healing assays and invasion capacity was assessed in Transwell chamber assays. Finally, to monitor ErbB pathway modulation by afatinib and related compounds, we used Western blot analyses.

RESULTS

Cell viability inhibition, as well as a reduction of motility and migration of osteosarcoma cell line were observed after treatment with afatinib. Likewise, in the HOS cell line, afatinib decreased phosphorylation of key components in the ErbB signaling pathway.

CONCLUSIONS

Afatinib shows relevant antitumor effect in several osteosarcoma cell lines, as it causes a significant impact on cell viability, motility, and migration with a significant decrease in the activation of ErbB pathway activity.

EWS promotes cell proliferation and inhibits cell apoptosis by regulating miR-199a-5p/Sox2 axis in osteosarcoma

OBJECTIVE

Osteosarcoma is one of the most common malignant bone tumors which mainly occurs in children and adolescents. It is characterized by high malignancy and high metastasis rate, resulting in high mortality and disability. Accumulating studies have validated that long noncoding RNAs (lncRNAs) exerted vital roles in multiple cancer progression by regulating the expression of specific genes. This work aimed to explore the potential molecular mechanism of EWS in osteosarcoma.

RESULTS

In this study, we discovered that both EWS and Sox2 were highly expressed in osteosarcoma tissue samples. In addition, the expression of EWS was positively associated with Sox2 level. We conducted a series of functional assays and observed that Sox2 overexpression could significantly overturned the enhancement of cell proliferation and the decline of cell apoptosis induced by EWS knockdown in osteosarcoma. Moreover, we found a key upstream regulatory gene of Sox2: miR-199a-5p.

CONCLUSIONS

Through molecular biology studies and rescue assays, we further demonstrated that EWS promotes tumor growth through the miR-199a-5p/Sox2 signaling axis in osteosarcoma. These findings may provide an important theoretical basis for the clinical diagnosis and treatment of osteosarcoma.

Autophagy regulation by microRNAs: Novel insights into osteosarcoma therapy

Osteosarcoma (OS) is a kind of primary bone cancer that is considered as the leading cause of children death. Surgery and chemotherapy are considered as common treatment approaches for OS; the rate of survival for patients is almost 60-70%. Besides the used therapeutic approaches, it seems that there is a crucial need to launch new treatments for OS. In this regard, more understanding about cellular and molecular pathways involved in OS can contribute to recovery and develop new therapeutic platforms. Autophagy is a cellular machinery that digests and degrades dysfunctional proteins and organelles, so it can regulate the cell proliferation and survival. Most of the time, OS cells use autophagy to increase their survival and proliferation and to gain the ability to resist chemotherapy. Although, there are several controversial evidences on how OS cells use autophagy. A variety of cellular and molecular pathways, that is, microRNAs (miRNAs) can modulate autophagy. MiRNAs are some endogenous, approximately 22 nucleotide RNAs that have an important role in posttranscriptional regulation of mRNAs by targeting them. There are many evidences that the various miRNA expressions in OS cells are dysregulated, so it can propel a normal cell to cancerous one by influencing the cell survival, apoptosis, and autophagy, and eventually increased chemoresitance. Hence, miRNAs can be considered as new biomarkers for OS diagnosis, and according to the role of autophagy in OS progression, miRNAs can use inhibiting or promoting autophagy agents. The present review summarizes the effects of aberrant expression of miRNAs in OS diagnosis and treatment with focus on their roles in autophagy.

GDF15 promotes osteosarcoma cell migration and invasion by regulating the TGF‑β signaling pathway

Growth and differentiation factor 15 (GDF15), a novel divergent member of the transforming growth factor‑β (TGF‑β) superfamily, was previously reported to be overexpressed in various types of cancers and was shown to be involved in tumor metastasis; however, the role of GDF15 in the development and malignant progression of osteosarcoma remains unclear. In the present study, reverse transcription‑quantitative polymerase chain reaction, western blot and ELISA analyses were performed to detect mRNA and protein expression, including that of GDF15, SMAD2 and SMAD3. Wound‑healing and cell invasion assays were conducted to determine the migratory and invasive abilities of osteosarcoma cells. A luciferase assay was performed to evaluate the transcriptional activity of a TGF‑β/SMAD‑responsive luciferase reporter. The Kaplan‑Meier method was used to generate survival curves, with a log‑rank test use to evaluate differences in survival. The results revealed that GDF15 expression was upregulated in metastatic osteosarcoma tissues compared with non‑metastatic osteosarcoma tissues. Patients with osteosarcoma that possessed high serum GDF15 levels exhibited significantly decreased overall survival (OS) and pulmonary metastasis‑free survival (PMFS) time compared with patients with low GDF15 expression. Furthermore, high serum GDF15 was an independent prognostic parameter for poor OS and short PMFS. Additionally, it was observed that the knockdown of GDF15 attenuated the migration and invasion of osteosarcoma cells. Silencing GDF15 markedly suppressed the TGF‑β signaling pathway. In conclusion, GDF15 may promote osteosarcoma cell metastasis by regulating the TGF‑β signaling pathway, and serum GDF15 levels may be a potential prognostic and pulmonary metastasis‑predictive biomarker in osteosarcoma.

Overexpression of miR-20a promotes the progression of osteosarcoma by directly targeting QKI2

Osteosarcoma (OS) is the most common type of malignant primary bone neoplasm. Although the application of neoadjuvant chemotherapy has improved the 5-year survival rate of patients suffering from OS, prognosis remains poor. Therefore, it is important to elucidate the molecular mechanisms underlying the occurrence, progression and metastasis of OS. The RNA-binding protein Quaking (QKI) is a member of the STAR family of proteins, and can function as a tumor suppressor gene to suppress the occurrence and progression of a variety of tumors; however, the role of QKI in OS remains to be fully elucidated. In the present study, it was identified that the expression of QKI2 was downregulated in OS using western blot analysis. In addition, subsequent functional investigations, including MTT, Transwell invasion and migration assays, revealed that QKI2 inhibited the proliferation, invasion and migration of an OS cell line in vitro. By implementing a series of experimental techniques in molecular biology, including reverse transcription-quantitative polymerase chain reaction and a double fluorescence reporter assay, it was demonstrated that the expression of miR-20a was high and inhibited the expression of QKI2 in OS. In conclusion, it was revealed that aberrantly upregulated miR-20a inhibited the expression of QKI2 in OS by targeting QKI2 mRNA, subsequently promoting the proliferation, migration and invasion of OS cells.

Effect of timing of pulmonary metastasis occurrence on the outcome of metastasectomy in osteosarcoma patients

BACKGROUND

Complete metastasectomy is the best predictor of survival in patients with osteosarcoma pulmonary metastases. There has been some controversy in the literature regarding the prognostic significance of the timing of occurrence of lung metastasis.

METHODS

We reviewed the clinical course of all osteosarcoma patients with pulmonary metastases treated by metastasectomy in our hospital from January 2008 through December 2016. Each patient who underwent metastasectomy was placed into one of three groups based on whether lung metastases were present at initial presentation (Group 1), developed during chemotherapy (Group 2), or appeared after completion of chemotherapy (Group 3). Data were obtained retrospectively and follow-up was obtained until the end of June 2017.

RESULTS

We identified 170 patients with pulmonary nodules of whom 99 (58.2%) underwent at least one metastasectomy (149 thoracotomies). Eleven patients had benign pulmonary nodules and were excluded. The other 88 patients were classified as Group 1 (37), Group 2 (18) or Group 3 (33). The median follow-up was 35 months (range 8 to 99). Postmetastasis 5-year overall survival (OS) was 38.1 ± 6.4%; event-free survival (EFS) was 25 ± 5.3%. By group, postmetastasis 5-year OS and EFS were 34.3 ± 13% and 18 ± 9.3% in Group 1, 8 ± 6.5% and 6.5 ± 5% in Group 2, and 52 ± 11.4% and 25 ± 9% in Group 3 (P < 0.001). In univariate analysis, the only significant factors associated with survival were timing of occurrence of lung metastasis and the number of lung nodules found.

CONCLUSION

The timing of occurrence of lung metastasis is an important prognostic factor among osteosarcoma patients eligible for metastasectomy. Patients whose metastases occurred during chemotherapy had the worst survival.

LEVEL OF EVIDENCE

Level II.

Activation of CXCL6/CXCR1/2 Axis Promotes the Growth and Metastasis of Osteosarcoma Cells in vitro and in vivo

Osteosarcoma (OS) is a malignant primary bone tumor with high metastatic rate. C-X-C motif chemokine ligand 6 (CXCL6) and its receptor C-X-C motif chemokine receptor 1/2 (CXCR1/2) have been found to participate in the process of carcinogenesis. In this study, we evaluated the role of CXCL6/CXCR1/2 axis in proliferation and metastasis of OS cells. According to our results, the mRNA and protein expressions of CXCL6, CXCR1, and CXCR2 in multiple OS cell lines were determined. Treatment with exogenous CXCL6 for more than 72 h significantly promoted the proliferation of OS cells. Blocking the effect of endogenous CXCL6 restrained the migration, invasion and epithelial-mesenchymal transition (EMT) as evidenced by increased E-cadherin level, decreased N-cadherin and Snail levels in OS cells. On the contrary, exogenous CXCL6 administration enhanced the migration and invasive abilities of OS cells. Moreover, silencing of CXCR1/2 suppressed migration, invasion and EMT of OS cells with or without treatment with exogenous CXCL6. In addition, exogenous CXCL6 promoted the activation of PI3K/AKT and β-catenin signaling pathways, which could be repressed by CXCR2 knockdown. Inactivation of PI3K/AKT or β-catenin pathway by specific inhibitors effectively suppressed CXCL6-induced migration, invasion and EMT of OS cells. Finally, overexpression of CXCL6 significantly contributed to tumor growth, pulmonary metastasis and activation of PI3K/AKT and β-catenin pathways in nude mice in vivo, which were repressed by treatment with CXCR2 antagonist. Our results suggest that CXCL6/CXCR1/2 axis promotes the proliferation and metastasis of OS cells.

Nitidine Chloride Inhibits SIN1 Expression in Osteosarcoma Cells

Nitidine chloride (NC) has been demonstrated to exert a tumor-suppressive function in various types of human cancers. However, the detailed mechanism of NC-mediated anti-tumor effects remains elusive. It has been reported that SIN1, a component of mTORC2 (mammalian target of rapamycin complex C2), plays an oncogenic role in a variety of human cancers. Therefore, the inhibition of SIN1 could be useful for the treatment of human cancers. In this study, we explored whether NC triggered an anti-cancer function via the inhibition of SIN1 in osteosarcoma (OS) cells. An MTT assay was performed to measure the effect of NC on the cell growth of osteosarcoma cells, and flow cytometry was used to detect the apoptotic rate of the cells after NC treatment. The expression of SIN1 was detected by western blotting. Wound-healing assay and Transwell chamber invasion assay were conducted to analyze the motility of osteosarcoma cells following NC exposure. We found that exposure to NC led to the inhibition of cell growth, migration, and invasion and the induction of apoptosis. Mechanistically, we found that NC inhibited the expression of SIN1 in osteosarcoma cells. Overexpression of SIN1 abrogated the inhibition of cell growth and motility induced by NC in osteosarcoma cells. Our results indicate that NC exhibits its tumor-suppressive activity via the inhibition of SIN1 in osteosarcoma cells, suggesting that NC could be a potential inhibitor of SIN1 in osteosarcoma.

Diosgenin exerts its tumor suppressive function via inhibition of Cdc20 in osteosarcoma cells

Osteosarcoma (OS) is one of the aggressive malignancies for young adults. Cdc20 (cell division cycle 20 homologue) has been reported to exhibit an oncogenic role in OS, suggesting that inhibition of Cdc20 could be a novel strategy for the treatment of OS. Since Cdc20 inhibitors have side effects, it is important to discover the new CDC20 inhibitors with non-toxic nature. In the present study, we determine whether natural agent diosgenin is an inhibitor of Cdc20 in OS cells. We performed MTT, FACS, Wound healing assay, Transwell, Western blotting, transfection assays in our study. We found diosgenin inhibited cell growth and induced apoptosis. Moreover, diosgenin exposure led to inhibition of cell migration and invasion. Notably, diosgenin inhibited the expression of Cdc20 in OS cells. Overexpression of Cdc20 abrogated the inhibition of cell growth and invasion induced by diosgenin. Our data reveal that inhibition of Cdc20 by diosgenin could be helpful for the treatment of patients with OS.

Platelet-Derived TGF-β Induces Tissue Factor Expression via the Smad3 Pathway in Osteosarcoma Cells

Over the last three decades, the prognosis of osteosarcoma has remained unchanged; the prognosis for patients with lung metastasis is still poor, and the development of new treatments is urgently required. We previously showed that aggressive osteosarcoma cells express more tissue factor (TF) and demonstrate enhanced extrinsic pathway capacity. Furthermore, tumor growth can be suppressed with the anticoagulant low molecular weight heparin. However, the molecular mechanisms underlying TF regulation are still unclear. Here, we report that transforming growth factor-β (TGF-β) upregulates TF, which can occur via activated platelets. TF was found to be expressed on osteosarcoma cell surfaces, which mediated the production of Xa and thrombin. TF induction by TGF-β was observed in several osteosarcoma cells, and especially in MG 63 cells. Both TF expression by TGF-β and extrinsic pathway activity through TF were rapidly increased. This reaction was inhibited by a TGF-β type I receptor inhibitor and TGF-β neutralizing antibody. Although TGF-β was found to phosphorylate both Smad2 and Smad3, their roles were markedly disparate. Surprisingly, Smad2 knockdown resulted in no inhibitory effect, whereas Smad3 knockdown completely suppressed TGF-β-induced TF expression. Next, data suggested that platelets were the source of TGF-β. We confirmed that thrombin-activated platelets and osteosarcoma cells could release TGF-β, and that platelet-derived TGF-β could induce TF expression. These processes were also inhibited by a TGF-β type I receptor inhibitor and Smad3 knockdown. Moreover, CD42b, TF, TGF-β, Smad2/3, and p-Smad2/3 were also detected in a biopsy sample from an osteosarcoma patient. Collectively, these finding suggested that the interaction between osteosarcoma cells and platelets, via thrombin and TGF-β, results in a continuous cycle, and that anti-platelet or anti-TGF-β therapy could be a promising tool for disease treatment. © 2018 American Society for Bone and Mineral Research.

TRIM2 regulates the development and metastasis of tumorous cells of osteosarcoma

The present study aimed to investigate candidate genes involved in the development and metastasis of osteosarcoma. Candidate genes were screened preliminarily from the Gene Expression Omnibus database and then validated using actual tumor tissues collected from patients with osteosarcoma. The cells were prepared and transfected with specific gene-targeted small interfering RNA followed by an MTS assay for cell viability detection and Transwell assays for cell migration and invasion capacity detection. The cell apoptosis was determined by flow cytometry and the protein level of the genes was detected by western blot analysis. An in vivo nude model was used and injected with cells to detect the functions of the genes. Transcriptome sequencing was performed to verify the regulation network, followed by reverse transcription-quantitative polymerase chain reaction and western blot analyses for validation. Increased tripartite motif-containing protein 2 (TRIM2) was detected in the osteosarcoma tumor tissues compared with normal tissues. The inhibition of TRIM2 induced lower cell viability and cell invasion capacity, and increased the rate of cell apoptosis. Decreased TRIM2 also inhibited the development and metastasis of osteosarcoma in the nude mouse models. The transcriptome sequencing revealed that the regulation of TRIM2 may be correlated with genes, Sirtuin 4, DNA damage inducible transcript 3, cAMP responsive element binding protein 5, G protein-coupled receptor 65 (GPR65) and ADP-ribosyltransferase 5. Western blot analysis indicated that TRIM2 regulated the development and metastasis of osteosarcoma via the phosphoinositide 3-kinase/protein kinase B signaling pathway. Therefore, TRIM2 performs important functions in regulating the development and metastasis of osteosarcoma.

CXCR1/Akt signaling activation induced by mesenchymal stem cell-derived IL-8 promotes osteosarcoma cell anoikis resistance and pulmonary metastasis

The loss of appropriate cell adhesion normally induces apoptosis via a process termed anoikis. The aim of this study was to investigate the effects of mesenchymal stem cells (MSCs) in the cancer microenvironment on the anoikis resistance and pulmonary metastasis of osteosarcoma (OS) cells, and to evaluate the critical role of the interleukin (IL)-8/C-X-C chemokine receptor (CXCR) 1/Akt-signaling pathway in these processes. Metastatic OS subtype cells, which did or did not interact with MSC-conditioned medium (MSC-CM) in vitro, were isolated from the pulmonary site and named Saos2-lung-M. Both MSC-CM and IL-8 treatment increased the anoikis resistance of Saos2 cells in vitro. Moreover, exogenous MSC-CM promoted the survival and metastasis of Saos2 cells in nude mice. Saos2-lung-M cells were more malignant and resistant to anoikis than parental cells. MSCs secreted IL-8, thereby protecting OS cells from anoikis. Blocking the IL-8/CXCR1/Akt pathway via CXCR1 knockdown inhibited the pulmonary metastasis of Saos2-lung-MSCs and prolonged the survival of tumor-bearing mice. In conclusion, MSCs enhanced OS cell resistance to anoikis and pulmonary metastasis via regulation of the IL-8/CXCR1/Akt pathway. These findings suggest that MSCs can “select for” OS cells with high metastatic potential in vivo, and highlight CXCR1 as a key target in the regulation of pulmonary metastasis of OS cells.

Meta-analysis of serum lactate dehydrogenase and prognosis for osteosarcoma

BACKGROUNDS

A large number of studies have reported the relationships between serum lactate dehydrogenase (LDH) and prognosis of osteosarcoma. However, the result is still controversial and no consensus has been reached. Therefore, we performed a meta-analysis to evaluate the prognostic role of serum LDH in osteosarcoma patients.

METHODS

We performed the systematic computerized search for eligible articles from PubMed, Embase, and Cochrane databases until December 21, 2017. The pooled hazard ratio (HR) and 95% confidence intervals (CIs) of overall survival (OS) and event-free survival (EFS) were obtained to assess the prognostic value of serum LDH.

RESULTS

A total of 18 studies with 2543 osteosarcoma patients were included. Overall, 15 studies assessed the elevated serum LDH level on OS and the pooled HR was 1.87 (95% CI = 1.58-2.20). Meanwhile, the pooled HR to evaluate the relationship between serum LDH and EFS in 9 studies was 1.78 (95% CI = 1.51-2.10). The same results were acquired when these studies were stratified by Enneking stage, geographic region, and sample size. No heterogeneity existed between these subgroups (P > .05). Begg's funnel plot and Egger's test (OS: P = .04; EFS: P = .34) showed that possible publication bias might exist in OS studies. Sensitivity analysis suggested the pooled HR was robust.

CONCLUSIONS

This meta-analysis demonstrates that elevated serum LDH level is apparently associated with lower EFS rate and serum LDH could be a prognostic biomarker for osteosarcoma patients.

miR-363-3p Inhibits Osteosarcoma Cell Proliferation and Invasion via Targeting SOX4

miR-363-3p has been shown to suppress tumor growth and metastasis in various human cancers. However, the function of miR-363-3p in osteosarcoma (OS) has not been determined. In our study, we found that the expression of miR-363-3p was significantly downregulated in OS tissues compared with adjacent normal tissues. miR-363-3p expression was associated with the poor overall survival rate of OS patients. Moreover, we found that overexpression of miR-363-3p markedly inhibited the proliferation, migration, and invasion of U2OS and MG63 cells. Moreover, we found that SOX4 was a direct target of miR-363-3p in OS cells. Overexpression of miR-363-3p significantly inhibited the expression of SOX4. Expression levels of miR-363-3p and SOX4 were negatively correlated in OS tissues. Finally, we found that restoration of SOX4 attenuated the suppressive effects of miR-363-3p on the proliferation, migration, and invasion of U2OS and MG63 cells. Therefore, our findings demonstrated that miR-363-3p served as a tumor suppressor in OS tissues by targeting SOX4.

Expression and therapeutic implications of cyclin-dependent kinase 4 (CDK4) in osteosarcoma

Overexpression and/or hyperactivation of cyclin-dependent kinase 4 (CDK4) has been found in many types of human cancers, and a CDK4 specific inhibitor, palbociclib, has been recently approved by the FDA for the treatment of breast cancer. However, the expression and the therapeutic potential of CDK4 in osteosarcoma remain unclear. In the present study, CDK4 was found to be highly expressed in human osteosarcoma tissues and cell lines as compared with normal human osteoblasts. Elevated CDK4 expression correlated with metastasis potential and poor prognosis in osteosarcoma patients as determined by immunohistochemical analysis in a human osteosarcoma tissue microarray (TMA). CDK4 inhibition by either palbociclib or specific small interference RNA (siRNA) exhibited dose-dependent inhibition of osteosarcoma cell proliferation and growth, accompanied by suppression of the CDK4/6-cyclinD-Rb signaling pathway. Flow cytometry analysis showed that CDK4 knockdown arrested osteosarcoma cells in the G1 phase of the cell cycle and induced cell apoptosis. Furthermore, inhibition of CDK4 significantly decreased osteosarcoma cell migration in vitro determined by the wound healing assay. These data highlight that CDK4 may be a potential promising therapeutic target in the treatment of human osteosarcoma.

Doxorubicin induces ZAKα overexpression with a subsequent enhancement of apoptosis and attenuation of survivability in human osteosarcoma cells

Human osteosarcoma (OS) is a malignant cancer of the bone. It exhibits a characteristic malignant osteoblastic transformation and produces a diseased osteoid. A previous study demonstrated that doxorubicin (DOX) chemotherapy decreases human OS cell proliferation and might enhance the relative RNA expression of ZAK. However, the impact of ZAKα overexpression on the OS cell proliferation that is inhibited by DOX and the molecular mechanism underlying this effect are not yet known. ZAK is a protein kinase of the MAPKKK family and functions to promote apoptosis. In our study, we found that ZAKα overexpression induced an apoptotic effect in human OS cells. Treatment of human OS cells with DOX enhanced ZAKα expression and decreased cancer cell viability while increasing apoptosis of human OS cells. In the meantime, suppression of ZAKα expression using shRNA and inhibitor D1771 both suppressed the DOX therapeutic effect. These findings reveal a novel molecular mechanism underlying the DOX effect on human OS cells. Taken together, our findings demonstrate that ZAKα enhances the apoptotic effect and decreases cell viability in DOX-treated human OS cells.

Knockdown of pyruvate kinase type M2 suppresses tumor survival and invasion in osteosarcoma cells both in vitro and in vivo

Osteosarcoma (OS) is the mostly diagnosed primary bone malignancy. Emerging evidence indicates that the activity of pyruvate kinase M2 (PKM2) isoform is crucial for the survival of tumor cells. In the present study, the effect of PKM2 knockdown on the proliferation and migration of OS cells were assessed both in vitro and in vivo. Small hairpin RNA (shRNA) technology were employed to suppress the expression of PKM2 in MG-63 and Saos-2 cell lines. In vitro, shRNA-mediated knockdown of PKM2 efficiently inhibited cell proliferation, and induced G1 cell cycle arrest and apoptosis in both cell lines, which was associated with decreased expressions of cyclin D1 and Bcl-2 as well as increased expressions of Bax, cleaved-caspase-3, and cleaved-PARP. The invasion and migration potential of OS cell lines were also inhibited by PKM2 knockdown through the regulating effect of PKM2 on MMP-2 and VEGF signaling. In vivo, knockdown of PKM2 decelerated tumor growth rate and induced structure deterioration in tumor tissues. The current study for the first time showed that the activity of PKM2 was indispensable for the development and metastasis of OS, thereby providing the basic information for the future development of PKM2-based anti-OS therapies.

Cell division cycle 20 promotes cell proliferation and invasion and inhibits apoptosis in osteosarcoma cells

Cdc20 (cell division cycle 20 homologue) has been reported to exhibit an oncogenic role in human tumorigenesis. However, the function of Cdc20 in osteosarcoma (OS) has not been investigated. In the current study, we aim to explore the role of Cdc20 in human OS cells. Multiple approaches were used to measure cell growth, apoptosis, cell cycle, migration and invasion in OS cells after depletion of Cdc20 or overexpression of Cdc20. We found that down-regulation of Cdc20 inhibited cell growth, induced apoptosis and triggered cell cycle arrest in OS cells. Moreover, Cdc20 down-regulation let to inhibition of cell migration and invasion in OS cells. Consistently, overexpression of Cdc20 in OS cells promoted cell growth, inhibited apoptosis, enhanced cell migration and invasion. Mechanistically, our Western blotting results showed that overexpression of Cdc20 reduced the expression of Bim and p21, whereas depletion of Cdc20 upregulated Bim and p21 levels in OS cells. Altogether, our findings demonstrated that Cdc20 exerts its oncogenic role partly due to regulation of Bim and p21 in OS cells, suggesting that targeting Cdc20 could be useful for the treatment of OS.

Antibiotic anisomycin induces cell cycle arrest and apoptosis through inhibiting mitochondrial biogenesis in osteosarcoma

The anti-cancer activities of antibiotic anisomycin have been demonstrated in kidney, colon and ovarian cancers whereas its underlying mechanisms are not well elucidated. In this work, we investigated whether anisomycin is effective in sensitizes osteosarcoma cell response to chemotherapy. We show that anisomycin inhibits proliferation via inducing osteosarcoma cell arrest at G2/M phase, accompanied by the increased levels of mitotic marker cyclin B and the decreased levels of Rb and E2F-1. Anisomycin also induces apoptosis in a caspase-dependent manner in osteosarcoma cells. Importantly, anisomycin is less effective in normal control NIH3T3 cells compared to osteosarcoma cells. In addition, anisomycin inhibits osteosarcoma growth in xenograft mouse model and enhances the inhibitory effects of doxorubicin in osteosarcoma in vitro and in vivo. Mechanistically, anisomycin targets mitochondrial biogenesis in osteosarcoma as shown by the decreased mitochondrial membrane potential, suppressed mitochondrial respiration via decreasing complex I activity, reduced ATP production. Furthermore, mitochondrial biogenesis stimulator acetyl-L-Carnitine (ALCAR) significantly rescues the inhibitory effects of anisomycin in osteosarcoma cells. Our work demonstrates that anisomycin is active against osteosarcoma cells and the molecular mechanism of its action is the inhibition of mitochondrial biogenesis.

Ouabain impairs cell migration, and invasion and alters gene expression of human osteosarcoma U-2 OS cells

Ouabain, the specific Na⁺ /K⁺ -ATPase blocker, has biological activity including anti-proliferative and anti-metastasis effects in cancer cell. There is no study to show ouabain inhibiting cell migration and invasion in human osteosarcoma U-2 OS cells. Thus, we investigated the effect of ouabain on the cell migration and invasion of human osteosarcoma U-2 OS cells. Results indicated that ouabain significantly decreased the percentage of viable cells at 2.5-5.0 μM, thus, we selected 0.25-1.0 μM for inhibiting studies. Ouabain inhibited cell migration, invasion and the enzymatic activities of MMP-2, and also affected the expression of metastasis-associated protein in U-2 OS cells. The cDNA microarray assay indicated that CDH1, TGFBR3, SHC3 and MAP2K6 metastasis-related genes were increased, but CCND1, JUN, CDKN1A, TGFB1, 2 and 3, SMAD4, MMP13, MMP2 and FN1 genes were decreased. These findings provide more information regarding ouabain inhibited cell migration and invasion and associated gene expressions in U-2 OS cells after exposed to ouabain.

MiR-200c regulates tumor growth and chemosensitivity to cisplatin in osteosarcoma by targeting AKT2

MicroRNAs (miRNAs) expression aberration has been discovered in almost all human cancers, thus offering a group of potential diagnostic markers, prognostic factors and therapeutic targets in tumorigenesis. Now our data showed that miR-200c, which is downregulated in osteosarcoma tissues, drives chemosensitivity to cisplatin in osteosarcoma. We demonstrated that AKT2 is a direct target of miR-200c, Spearman’s rank correlation analysis showed that the expression levels of AKT2 and miR-200c in 35 pairs of osteosarcoma specimens were inversely correlated. Moreover, miR-200c inhibited cell proliferation and cell migration. Taken together, for the first time, our results demonstrate that miR-200c plays a significant role in osteosarcoma tumor growth and chemosensitivity by regulating AKT2, which may provide a novel therapeutic strategy for treatment of osteosarcoma.

S-phase kinase-associated protein 2 promotes cell growth and motility in osteosarcoma cells

Skp2 (S-phase kinase-associated protein 2) plays an oncogenic role in a variety of human cancers. However, the function of Skp2 in osteosarcoma (OS) is elusive. Therefore, in the current study, we explore whether Skp2 exerts its oncogenic function in OS. The cell growth, apoptosis, invasion and cell cycle were measured in OS cells after Skp2 overexpression. We found that overexpression of Skp2 enhanced cell growth, and inhibited cell apoptosis in OS cells. Moreover, we observed that upregulation of Skp2 accelerated cell cycle progression in OS cells. Furthermore, the ability of migration and invasion was enhanced in Skp2 overexpressing OS cells. Mechanically, our Western blotting data suggested that Skp2 decreased the expression of E-cadherin, Foxo1, p21, and p57, but increased MMP-9 in OS cells. In conclusion, our study demonstrated that Skp2 exhibited an oncogenic function in OS cells, suggesting that inhibition of Skp2 may be a novel approach for the treatment of OS.

Fangchinoline suppresses the proliferation, invasion and tumorigenesis of human osteosarcoma cells through the inhibition of PI3K and downstream signaling pathways

Osteosarcoma is the most common malignant bone tumor. Most patients diagnosed with osteosarcoma are less than 20 years of age. Osteosarcoma cells proliferate rapidly and invade other tissues. At present, neoadjuvant chemotherapy is the primary pharmacodynamic strategy to prevent the progression of osteosarcoma. However, adverse effects of this strategy limit its long-term application. Previous research has shown that fangchinoline exerts antitumor effects on several types of tumor cells; however, its effect on osteosarcoma cells remains unknown. The present study evaluated the effects of fangchinoline on the proliferation, apoptosis, migration and invasion of osteosarcoma cells in vitro and on their tumorigenesis in vivo and determined the possible underlying mechanism of action. Fangchinoline-treated MG63 and U20S cells showed significantly decreased proliferation and significantly increased apoptosis. Fangchinoline markedly suppressed the migration and invasion of the MG63 cells. Fangchinoline-treated MG63 cells showed significantly decreased expression of phosphoinositide 3-kinase (PI3K) and Akt^p-Thr308. Moreover, fangchinoline-treated MG63 cells showed downregulated expression of cyclin D1 and matrix metalloproteinase 2 and 9, which act downstream of PI3K, and upregulated expression of caspase-3 and caspase-8. Furthermore, fangchinoline suppressed the growth of subcutaneous osteosarcoma tumors in Balb/c mice subcutaneously injected with osteosarcoma cells. These findings suggest that fangchinoline inhibits the progression of osteosarcoma by suppressing the proliferation, migration and invasion and by accelerating the apoptosis of osteosarcoma cells. In addition, our results suggest that the mechanism underlying the antitumor effects of fangchinoline involve the inhibition of PI3K and its downstream signaling pathways.

Heat shock transcription factor 1 promotes the proliferation, migration and invasion of osteosarcoma cells

OBJECTIVES

Osteosarcoma is the most commonly diagnosed primary malignancy of bone and its overall survival rate is still very low. The molecular mechanisms underlying the progression of osteosarcoma have not been clearly illuminated. Heat shock transcription factor 1 (HSF1) is a key regulator of the heat shock response and also plays important roles in many cancers, but its function in osteosarcoma remains unexplored.

MATERIALS AND METHODS

In this study, the proliferation of osteosarcoma cells was determined by Cell Counting Kit-8 assays and colony formation assays. Transwell assays were used to demonstrate the migration and invasion abilities of osteosarcoma cells. A tumour formation assay in a nude mouse model was performed to assess the effect of HSF1 on osteosarcoma cell growth in vivo. The protein levels of HSF1 were analysed with immunohistochemical staining in samples from osteosarcoma patients.

RESULTS

We demonstrated that knockdown of HSF1 reduced the proliferation, migration and invasion of osteosarcoma cells, while overexpression of HSF1 promoted the proliferation, migration and invasion of osteosarcoma cells. Furthermore, HSF1 promoted the proliferation of osteosarcoma cells in vivo. In addition, high levels of HSF1 were associated with a poor prognosis in osteosarcoma.

CONCLUSIONS

These data highlight an important role of HSF1 in proliferation, migration and invasion of osteosarcoma cells. Moreover, the expression of HSF1 was associated with prognosis in osteosarcoma.

MiR-451 suppresses proliferation, migration and promotes apoptosis of the human osteosarcoma by targeting macrophage migration inhibitory factor

Previous studies have shown that MiR-451 plays an important role in human osteosarcoma carcinogenesis, but the underlying mechanism by which MiR-451 affects the osteosarcoma has not been fully understood. This study intends to uncover the mechanism by which MiR-451 functions as a tumor suppressor. The expression of MiR-451 in osteosarcoma tissues and osteosarcoma cell lines was monitored by real-time PCR. The proliferation ability was examined by MTT and cell cycle assay. The migration and apoptosis of cells were monitored by migration assay and flow cytometry, respectively. Moreover, the angiogenesis of HUVEC cells transfected with MiR-451 mimics was examined by tube formation assay. The effect of MiR-451 on MIF was determined by luciferase assays and Western blot assay. The results showed that MiR-451 expression level was significantly reduced in the osteosarcoma compared with normal bone tissues. Overexpression of MiR-451 significantly attenuated the proliferation and migration, and induced the apoptosis of osteosarcoma cells. Furthermore, the angiogenesis of HUVEC cells transfected with MiR-451 mimics was assayed and the decreased angiogenic ability was detected compared to the controls. Finally, we demonstrated that MiR-451 overexpression inhibited the malignant behavior of osteosarcoma by downregulating MIF. These findings suggest that MiR-451 may act as a tumor suppressor in osteosarcoma. MiR-451 inhibited cell proliferation, migration and angiogenesis and promoted apoptosis of human osteosarcoma cells, at least partially, by inhibiting the expression of MIF. MiR-451/MIF may be a novel therapeutic target in treatment of osteosarcoma.

BMPR2 and HIF1- overexpression in resected osteosarcoma correlates with distant metastasis and patient survival

Objective

Bone morphogenetic protein receptor 2 (BMPR2) and hypoxia-inducible factor 1-α (HIF1-α) existed abnormal expression in several types of cancer. However, their expressions and related roles in osteosarcoma are largely unknown.

Methods

To investigate the clinical significance of BMPR2 and HIF1-α in osteosarcoma, we analyzed their expression levels in 103 osteosarcoma specimens by immunochemistry. Meanwhile, we conducted a follow-up to examine the metastatic behavior and overall survival (OS) of osteosarcoma patients.

Results

Among 103 tissues, 61 cases had BMPR2-positive expression and 57 cases had HIF1-α positive expression. A significant correlation was noticed between BMPR2 and HIF1-α expression in osteosarcoma specimens (P=0.035). Receiver-operating characteristic (ROC) curves were calculated to investigate the predictive value of the two markers in tumor metastasis. By means of univariate and multivariate analysis, BMPR2 and HIF1-α expression, as well as higher tumor grade, were identified as significant risk factors for OS in patients with osteosarcoma. Kaplan-Meier survival analysis revealed that the patients with BMPR2 and HIF1-α positive expression had worse OS compared with patients with BMPR2-negative or HIF1-α-negative staining.

Conclusions

It can be concluded that BMPR2 and HIF1-α expression is highly correlated with metastatic behavior in patients with osteosarcoma and can serve as predictive markers for metastasis and OS of these patients.

Effect of Unplanned Therapy on the Prognosis of Patients with Extremity Osteosarcoma

Unplanned therapy for extremity osteosarcoma can result in erroneous surgical procedures and lack of neoadjuvant chemotherapy before the first operation. Our aim was to compare the prognosis between patients with extremity osteosarcoma who received unplanned therapy and those who received standard treatment. This was a retrospective review of patients with extremity osteosarcoma who received appropriate surgical treatment and neoadjuvant chemotherapy (n = 79) and those who received unplanned therapy (n = 24) between June 2000 and October 2014. Survival rate, local recurrence rate and metastasis rate were compared between the two groups. We found that patients who had unplanned therapy had a higher local recurrence rate (41.7% vs. 21.5%; P = 0.049) and a shorter mean time for recurrence (8.90 vs. 14.59 months; P = 0.018). There was no significant difference between groups in the 5-year survival rate (56.3% vs.67.8%; P = 0.356), metastasis rate (45.8% vs. 30.4%; P = 0.125) and mean time to metastasis (23.18 vs.18.24 months; P = 0.396). Our findings suggest that unplanned therapy for extremity osteosarcoma can result in failure of local control. The use of supplementary interventions after unplanned therapy, such as neoadjuvant chemotherapy and limb salvage surgery, may explain the similar survival and metastasis rates between patients receiving unplanned therapy and those receiving standard treatment.

TGF-β Signaling in Bone Remodeling and Osteosarcoma Progression

Osteosarcomas are the most prevalent malignant primary bone tumors in children. Despite intensive efforts to improve both chemotherapeutics and surgical management, 40% of all osteosarcoma patients succumb to the disease. Specifically, the clinical outcome for metastatic osteosarcoma remains poor; less than 30% of patients who present metastases will survive five years after initial diagnosis. Treating metastatic osteosarcoma thus remains a challenge. One of the main characteristics of osteosarcomas is their ability to deregulate bone remodelling. The invasion of bone tissue by tumor cells indeed affects the balance between bone resorption and bone formation. This deregulation induces the release of cytokines or growth factors initially trapped in the bone matrix, such as transforming growth factor-β (TGF-β), which in turn promote tumor progression. Over the past years, there has been considerable interest in the TGF-β pathway within the cancer research community. This review discusses the involvement of the TGF-β signalling pathway in osteosarcoma development and in their metastatic progression.

miR-10b promotes invasion by targeting KLF4 in osteosarcoma cells

OBJECTIVE

Osteosarcoma is a common malignancy with high rate of metastasis. miR-10b has been reported to be expressed in many types of tumors abnormally and be associated with cancer carcinogenesis and progression. But the function of miR-10b in osteosarcoma is still unknown. So this study was aimed to investigate the role of miR-10b in osteosarcoma development.

METHODS

miR-10b expression in osteosarcoma tissues and osteosarcoma cells were detected using real time PCR. The effects of miR-10b on osteosarcoma cells proliferation, apoptosis, migration and invasion were detected using CCK-8 assay, flow cytometry, wound-healing assay and transwell assay, respectively. The relationship between miR-10b and KLF4 was evaluated using dual-luciferase assay, correlation analysis.

RESULTS

miR-10b was highly expressed in osteosarcoma tissues and osteosarcoma cells. Furthermore, inhibition of miR-10b in osteosarcoma cells depressed the cells proliferation, migration and invasion but promoted cells apoptosis. In addition, KLF4 was down-regulated by miR-10b and miR-10b expression was negatively related to KLF4 expression in osteosarcoma tissue, miR-10b participated in the process of osteosarcoma cells invasion by regulating KLF4 expression.

CONCLUSION

miR-10b is overexpressed in osteosarcoma and KLF4 is the direct target gene of miR-10b. Furthermore, miR-10b promotes osteosarcoma cells progression by downregulating KLF4 expression. These results suggest that miR-10b functions as an oncomiR and play an important role in osteosarcoma cellular processes at least partially through regulating KLF4; miR-10b may be a therapeutic target for osteosarcoma treatment.

Meta-analysis of alkaline phosphatase and prognosis for osteosarcoma

Many studies have evaluated the relationships between alkaline phosphatase (ALP) levels and the prognosis for osteosarcoma. However, a consensus has yet to be reached. We completed a meta-analysis to assess the significance of ALP and prognosis for osteosarcoma. We retrieved eligible documents from the PubMed and Embase databases and extracted related data from those documents. The overall survival (OS), hazard ratio (HR) and event-free survival (EFS) HR were obtained after combination to evaluate the impacts of ALP levels on prognosis for osteosarcoma. After screening, a total of 12 documents published between 1999 and 2013 were included. The ALP levels on OS were evaluated in nine documents. The pooled HRs was 1.78 (95% CI: 1.52-2.07, p < .05). The ALP levels on EFS were determined in eight documents. The pooled HRs was 1.58 (95% CI: 1.37-1.82, p < .05). Begg's test (OS, p > .754; EFS, p > .386) and Egger's test (OS, p > .649; EFS, p > .274) showed that there was no significant publication bias during analytic process. In summary, our meta-analysis shows that a higher level of ALP can decrease the OS and EFS in patients with osteosarcoma and ALP is an important biological indicator for patients with osteosarcoma.

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.