Recent advances in the management of osteosarcoma and forthcoming therapeutic strategies

Role of MTH1 in oxidative stress and therapeutic targeting of cancer

Cancer cells maintain high levels of reactive oxygen species (ROS) to drive their growth, but ROS can trigger cell death through oxidative stress and DNA damage. To survive enhanced ROS levels, cancer cells activate their antioxidant defenses. One such defense is MTH1, an enzyme that prevents the incorporation of oxidized nucleotides into DNA, thus preventing DNA damage and allowing cancer to proliferate. MTH1 levels are often elevated in many cancers, and thus, inhibiting MTH1 is an attractive strategy for suppressing tumor growth and metastasis. Targeted MTH1 inhibition can induce DNA damage in cancer cells, exploiting their vulnerability to oxidative stress and selectively targeting them for destruction. Targeting MTH1 is promising for cancer treatment because normal cells have lower ROS levels and are less dependent on these pathways, making the approach both effective and specific to cancer. This review aims to investigate the potential of MTH1 as a therapeutic target, especially in cancer treatment, offering detailed insights into its structure, function, and role in disease progression. We also discussed various MTH1 inhibitors that have been developed to selectively induce oxidative damage in cancer cells, though their effectiveness varies. In addition, this review provide deeper mechanistic insights into the role of MTH1 in cancer prevention and oxidative stress management in various diseases.

Menadione and protocatechuic acid: A drug combination with antitumor effects in murine osteosarcoma cells

Osteosarcoma (OS) is a primary malignant bone tumor that has an abnormal expression of oncogenesis and tumor suppressors and causes dysregulation of various signaling pathways. Thus, novel therapeutic strategies for OS are needed to overcome the resistance of traditional treatments. This study evaluated the cytotoxic and anticancer effects of the association between menadione (MEN) and protocatechuic acid (PCA) in murine OS cells (UMR-106). The concentrations were 3.12 μM of isolated MEN, 500 μM of isolated PCA, and their associations. We performed cell viability assays, morphology modification analysis, cell migration by the wound-healing method, apoptosis by flow cytometry, reactive oxygen species (ROS) production, gene expression of NOX by RT-qPCR, and degradation of MMP-2 and 9 by zymography. Our results showed that the association of MEN+PCA was more effective in OS cells than the compounds alone. The association decreased cell viability, delayed cell migration, and decreased the expression of NOX-2 and ROS. In addition, the MEN+PCA association induced a slight increase in the apoptotic process. In summary, the association can enhance the compound's antitumor effects and establish a higher selectivity for tumor cells, possibly caused by significant mitochondrial damage and antioxidant properties.

A novel circular RNA circRBMS3 regulates proliferation and metastasis of osteosarcoma by targeting miR-424-eIF4B/YRDC axis

Circular RNAs (circRNAs) have been demonstrated to have critical regulatory roles in tumorigenesis. However, the contribution of circRNAs to OS (osteosarcoma) remains largely unknown. circRNA deep sequencing was performed to the expression of circRNAs between OS and chondroma tissues. The regulatory and functional role of circRBMS3 (a circRNA derived from exons 7 to 10 of the RBMS3 gene, hsa_circ_0064644) upregulation was examined in OS and was validated in vitro and in vivo, upstream regulator and downstream target of circRBMS3 were both explored. RNA pull down, a luciferase reporter assay, biotin-coupled microRNA capture and fluorescence in situ hybridization were used to evaluate the interaction between circRBMS3 and micro (mi)-R-424-5p. For in vivo tumorigenesis experiments, Subcutaneous and Orthotopic xenograft OS mouse models were built. Expression of circRBMS3 was higher in OS tissues due to the regulation of adenosine deaminase 1-acting on RNA (ADAR1), an abundant RNA editing enzyme. Our in vitro data indicated that ShcircRBMS3 inhibits the proliferation and migration of osteosarcoma cells. Mechanistically, we showed that circRBMS3 could regulate eIF4B and YRDC, through 'sponging' miR-424-5p. Furthermore, knockdown of circRBMS3 inhibited malignant phenotypes and bone destruction of OS in vivo. Our results reveal an important role for a novel circRBMS3 in the growth and metastasis of malignant tumor cells and offer a fresh perspective on circRNAs in OS progression.

The synergistic anticancer effect of CBD and DOX in osteosarcoma

BACKGROUND

Osteosarcoma is a malignant tumor that can present with pain in the bones, joints, and local masses. The incidence is highest in adolescents, and the most common sites are the distal femur, proximal tibia and proximal humerus metaphyseal. Doxorubicin is the first-line chemotherapeutic agent for the treatment of osteosarcoma, but it has many side effects. Cannabidiol is a non-psychoactive plant cannabinoid cannabinol (CBD) that has been shown to be effective against osteosarcoma; however, the molecular targets and mechanisms of CBD action in osteosarcoma remain unclear.

METHODS

Cell proliferation, migration, invasion and colony formation were analyzed using two drugs alone or in combination to evaluate their inhibitory effects on the malignant characteristics of OS cells. Apoptosis and the cell cycle were detected by flow cytometry. The synergistic inhibitory effect of doxorubicin/cannabidiol on tumors was also detected in nude mouse xenotransplantation models.

RESULTS

Through analysis of two osteosarcoma cell lines, MG63 and U2R, it was found that the cannabidiol/doxorubicin combination treatment synergistically inhibited growth, migration and invasion and induced apoptosis, blocking G2 stagnation in OS cells. Further mechanistic exploration suggests that the PI3K-AKT-mTOR pathway and MAPK pathway play an important role in the synergistic inhibitory effect of the two drugs in osteosarcoma. Finally, in vivo experimental results showed that the cannabidiol/doxorubicin combination treatment significantly reduced the number of tumor xenografts compared to cannabidiol alone or doxorubicin alone.

CONCLUSIONS

Our findings in this study suggest that cannabidiol and doxorubicin have a synergistic anticancer effect on OS cells, and their combined application may be a promising treatment strategy for OS.

A four-lncRNA risk signature for prognostic prediction of osteosarcoma

Aim: Osteosarcoma is the most common primary malignant tumor of bone. However, our understanding of the prognostic indicators and the genetic mechanisms of the disease progression are still incomplete. The aim of this study was to identify a long noncoding RNA (lncRNA) risk signature for osteosarcoma survival prediction. Methods: RNA sequencing data and relevant clinical information of osteosarcoma patients were downloaded from the database of Therapeutically Applicable Research to Generate Effective Treatments (TARGET). We analyzed the differentially expressed lncRNAs between deceased and living patients by univariate and multivariate Cox regression analysis to identify a risk signature. We calculated a prognostic risk score for each sample according to this prognosis signature, and divided patients into high-risk and low-risk groups according to the median value of the risk score (0.975). Kaplan-Meier analysis and receiver operating characteristic (ROC) curve statistics were used to evaluate the performance of the signature. Next, we analyzed the signature's potential function through Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene-set enrichment analysis (GSEA). Lastly, qRT-PCR was used to validate the expression levels of the four lncRNAs in clinical samples. Results: Twenty-six differentially expressed lncRNAs were identified between deceased and living patients. Four of these lncRNAs (CTB-4E7.1, RP11-553A10.1, RP11-24N18.1, and PVRL3-AS1) were identified as independent prognostic factors, and a risk signature of these four lncRNAs for osteosarcoma survival prediction was constructed. Kaplan-Meier analysis showed that the five-year survival time in high-risk and low-risk groups was 33.1% and 82.5%, and the area under the curve (AUC) of the ROC was 0.784, which demonstrated that the prognostic signature was reliable and had the potential to predict the survival of patients with osteosarcoma. The expression level of the four lncRNAs in osteosarcoma tissues and cells was determined by qRT-PCR. Functional enrichment analysis suggested that the signature might be related to osteosarcoma through regulation of the MAPK signaling pathway, the PI3K-Akt signaling pathway, and the extracellular matrix and also provided new insights into the study of osteosarcoma, including the role of papillomavirus infection, olfactory receptor activity, and olfactory transduction in osteosarcoma. Conclusion: We constructed a novel lncRNA risk signature that served as an independent biomarker for predicting the prognosis of osteosarcoma patients.

Origin and Therapies of Osteosarcoma

Simple Summary

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

Abstract

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

The synergistic anticancer effect of the bromodomain inhibitor OTX015 and histone deacetylase 6 inhibitor WT-161 in osteosarcoma

Background

Osteosarcoma (OS) is a tumour with a high malignancy level and a poor prognosis. First-line chemotherapy for OS has not been improved for many decades. Bromodomain and extraterminal domain (BET) and histone deacetylases (HDACs) regulate histone acetylation in tandem, and BET and HDACs have emerged as potential cancer therapeutic targets.

Methods

Cell proliferation, migration, invasion, colony formation, and sphere-forming assays were performed with the two inhibitors alone or in combination to evaluate their suppressive effect on the malignant properties of OS cells. Apoptosis and the cell cycle profile were measured by flow cytometry. The synergistic inhibitory effect of OTX015/WT-161 on tumours was also examined in a nude mouse xenograft model.

Results

The combined therapy of OTX015/WT-161 synergistically inhibited growth, migration, and invasion and induced apoptosis, resulting in G1/S arrest of OS cells. Additionally, OTX015/WT-161 inhibited the self-renewal ability of OS stem cells (OSCs) in a synergistic manner. Further mechanistic exploration revealed that the synergistic downregulation of β-catenin by OTX015-mediated suppression of FZD2 and WT-161-mediated upregulation of PTEN may be critical for the synergistic effect. Finally, the results of an in vivo assay showed that tumour xenografts were significantly decreased after treatment with the OTX015/WT-161 combination compared with OTX015 or WT-161 alone.

Conclusions

Our findings in this study demonstrated that OTX015 and WT-161 had synergistic anticancer efficacy against OS, and their combination might be a promising therapeutic strategy for OS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02443-y.

A five metastasis-related long noncoding RNA risk signature for osteosarcoma survival prediction

BACKGROUND

Osteosarcoma is a highly malignant and common bone tumour with an aggressive disease course and a poor prognosis. Previous studies have demonstrated the relationship between long noncoding RNAs (lncRNAs) and tumorigenesis, metastasis, and progression.

METHODS

We utilized a large cohort from the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database osteosarcoma project to identify potential lncRNAs related to the overall survival of patients with osteosarcoma by using univariate and multivariate Cox proportional hazards regression analyses. Kaplan-Meier curves were generated to evaluate the overall survival difference between patients in the high-risk group and the low-risk group. A time-dependent receiver operating characteristic curve (ROC) was employed, and the area under the curve (AUC) of ROC was measured to assess the sensitivity and specificity of the multi-lncRNA signature.

RESULTS

Five lncRNAs (RP11-128N14.5, RP11-231|13.2, RP5-894D12.4, LAMA5-AS1, RP11-346L1.2) were identified, and a five-lncRNA signature was constructed. The AUC for predicting 5-year survival was 0.745, which suggested good performance of the five-lncRNA signature. In addition, functional enrichment analysis of the five-lncRNA-correlated protein-coding genes (PCGs) was performed to show the biological function of the five lncRNAs. Additionally, PPI network suggested RTP1 is a potential biomarker that regulates the prognosis of osteosarcoma.

CONCLUSIONS

We developed a five-lncRNA signature as a potential prognostic indicator for osteosarcoma.

Mechanisms of Resistance to Conventional Therapies for Osteosarcoma

Osteosarcoma (OS) is the most common primary bone tumor, mainly occurring in children and adolescents. Current standard therapy includes tumor resection associated with multidrug chemotherapy. However, patient survival has not evolved for the past decades. Since the 1970s, the 5-year survival rate is around 75% for patients with localized OS but dramatically drops to 20% for bad responders to chemotherapy or patients with metastases. Resistance is one of the biological processes at the origin of therapeutic failure. Therefore, it is necessary to better understand and decipher molecular mechanisms of resistance to conventional chemotherapy in order to develop new strategies and to adapt treatments for patients, thus improving the survival rate. This review will describe most of the molecular mechanisms involved in OS chemoresistance, such as a decrease in intracellular accumulation of drugs, inactivation of drugs, improved DNA repair, modulations of signaling pathways, resistance linked to autophagy, disruption in genes expression linked to the cell cycle, or even implication of the micro-environment. We will also give an overview of potential therapeutic strategies to circumvent resistance development.

Comprehensive Analysis of Aerobic Exercise-Related Genes Identifies CDCA4 That Promotes the Progression of Osteosarcoma

Background

Exercise has a positive impact on patients with osteosarcoma, improving function, reducing disability, maintaining independence and quality of life. Exercise may also directly affect the effectiveness of cancer treatment. Cell division cycle-associated protein 4 (CDCA4) is reported to function importantly during numerous human cancers development. Nevertheless, the details toward CDCA4 function are still to be investigated.

Methods

This study comprehensively analyzed the GSE74194 database and obtained aerobic exercise-related genes. Protein-protein interaction network (PPI) and Gene Ontology (GO) analysis were performed on the differentially expressed genes (DEGs). Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and tumor genome atlas (TCGA) data mining were applied to measure aerobic exercise-related gene CDCA4 level in osteosarcoma tissue. We conducted lots of functional experiments to uncover CDCA4 function and its corresponding mechanism in osteosarcoma.

Results

We screened a total of 547 DEGs related to aerobic exercise, of which 373 were up-regulated and 174 were down-regulated. PPI analysis revealed 90 genes that might play key roles. GO analysis showed that aerobic exercise-related DEGs were significantly enriched during the mitotic cell cycle, cell division, mitotic nuclear division and sister chromatid segregation, nuclear division, microtubule cytoskeleton organization involved protein, microtubule-based process, spindle organization, G2/M transition of mitotic cell cycle. Our results indicated that CDCA4 was increased in osteosarcoma tissues and cell lines, and its level had association with high mortality of osteosarcoma patients. Further studies revealed that absence of CDCA4 largely hindered osteosarcoma cancer cell proliferation, invasion, and migration.

Conclusion

Comprehensive bioinformatics analysis improves our understanding of the underlying molecular mechanisms of aerobic exercise on osteosarcoma. This provides evidence for the effect of aerobic exercise on CDCA4 expression. Our data suggested that CDCA4 could facilitate osteosarcoma development, and gave a hint that CDCA4 was a candidate target in the treatment of osteosarcoma, aerobic exercise might help the treatment and prognosis of patients with osteosarcoma.

CircUBAP2 promotes SEMA6D expression to enhance the cisplatin resistance in osteosarcoma through sponging miR-506-3p by activating Wnt/β-catenin signaling pathway

The occurrence of chemo-resistance is an essential reason for the high morbidity of osteosarcoma (OS) patients. Circular RNAs (circRNAs) have been involved in the regulation of chemo-resistance in cancers. Semaphorins 6D (SEMA6D) is abnormally expressed in many cancers. However, the roles of circUBAP2 and SEMA6D in the chemo-resistance of OS are still unclear. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression levels of circUBAP2, SEMA6D and microRNA-506-3p (miR-506-3p). The cisplatin resistance and proliferation of cells were evaluated by 3-(4, 5-dimethyl-2 thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide assay. Western blot analysis was performed to measure the protein levels of Wnt/β-catenin signaling pathway biomarkers and SEMA6D. Also, the apoptosis, migration and invasion of cells were assessed by Flow cytometry and Transwell assays, respectively. Besides, Dual-luciferase reporter assay was used to verify the interaction between miR-506-3p and circUBAP2 or SEMA6D. We found that the expression levels of circUBAP2 and SEMA6D were increased in cisplatin-resistant OS tissues and cells. Knockdown of circUBAP2 inhibited the cisplatin resistance, silenced Wnt/β-catenin signaling pathway, hindered cell proliferation, migration and invasion, and promoted apoptosis in cisplatin-resistant OS cells, all of which could be reversed by overexpression of SEMA6D. MiR-506-3p could be sponged by circUBAP2 and could target SEMA6D. The suppression of miR-506-3p overexpression on the progression of OS cisplatin resistance could be reversed by SEMA6D overexpression, while miR-506-3p inhibitor also could invert the inhibitory effect of circUBAP2 silencing on the progression of OS cisplatin resistance. In conclusion, CircUBAP2 and SEMA6D played active roles in the progression of OS cisplatin resistance through miR-506-3p, which might provide some new ideas for studying the countermeasures of OS resistance.

CircUBAP2 promotes SEMA6D expression to enhance the cisplatin resistance in osteosarcoma through sponging miR-506-3p by activating Wnt/β-catenin signaling pathway

The occurrence of chemo-resistance is an essential reason for the high morbidity of osteosarcoma (OS) patients. Circular RNAs (circRNAs) have been involved in the regulation of chemo-resistance in cancers. Semaphorins 6D (SEMA6D) is abnormally expressed in many cancers. However, the roles of circUBAP2 and SEMA6D in the chemo-resistance of OS are still unclear. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression levels of circUBAP2, SEMA6D and microRNA-506-3p (miR-506-3p). The cisplatin resistance and proliferation of cells were evaluated by 3-(4, 5-dimethyl-2 thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide assay. Western blot analysis was performed to measure the protein levels of Wnt/β-catenin signaling pathway biomarkers and SEMA6D. Also, the apoptosis, migration and invasion of cells were assessed by Flow cytometry and Transwell assays, respectively. Besides, Dual-luciferase reporter assay was used to verify the interaction between miR-506-3p and circUBAP2 or SEMA6D. We found that the expression levels of circUBAP2 and SEMA6D were increased in cisplatin-resistant OS tissues and cells. Knockdown of circUBAP2 inhibited the cisplatin resistance, silenced Wnt/β-catenin signaling pathway, hindered cell proliferation, migration and invasion, and promoted apoptosis in cisplatin-resistant OS cells, all of which could be reversed by overexpression of SEMA6D. MiR-506-3p could be sponged by circUBAP2 and could target SEMA6D. The suppression of miR-506-3p overexpression on the progression of OS cisplatin resistance could be reversed by SEMA6D overexpression, while miR-506-3p inhibitor also could invert the inhibitory effect of circUBAP2 silencing on the progression of OS cisplatin resistance. In conclusion, CircUBAP2 and SEMA6D played active roles in the progression of OS cisplatin resistance through miR-506-3p, which might provide some new ideas for studying the countermeasures of OS resistance.

Enoxacin inhibits proliferation and invasion of human osteosarcoma cells and reduces bone tumour volume in a murine xenograft model

Osteosarcoma is the most prevalent primary bone malignancy in children and adolescents. Neoadjuvant chemotherapy combined with surgical resection, the current standard treatment of osteosarcoma, is associated with a 5-year survival rate of only ~70%. Therefore, it is necessary to identify new, more effective treatment strategies for patients with this lethal disease. Enoxacin is a highly effective broad-spectrum fluoroquinolone antibiotic with low toxicity. The drug inhibits the growth and metastasis of numerous tumour types, but its efficacy has not been studied in osteosarcoma. This study assessed the antitumour effects of enoxacin in osteosarcoma 143B cells and in a murine tumour xenograft model. Enoxacin inhibited the proliferation, invasion and migration of 143B cells, as well as inducing their apoptosis. These effects were thought to be mediated by downregulation of Bcl-xL, Bxl-2, matrix metalloproteinase (MMP)2 and MMP9 expression. Enoxacin also significantly impaired the growth of bone tumours in nude mice without affecting their liver or kidney function, or blood cell count. Collectively, these results indicate that enoxacin is a promising new drug for osteosarcoma that warrants further evaluation in clinical studies.

What is the best clinical approach to recurrent/refractory osteosarcoma?

Introduction: Osteosarcoma is the most common malignant bone tumor. It is currently treated with pre-and postoperative chemotherapy, associated with surgical resection of the tumor.Area covered: Relapses occur in about one in three patients presenting with localized disease, and three in four of those with metastases at diagnosis. Relapsing disease carries a very poor prognosis, with 5-year survival rates ranging between 13% and 40%.Expert opinion: Patients with unilateral lung involvement or solitary lung metastases and a recurrence-free interval (RFI) longer than 24 months have a better prognosis, and could be managed with surgical resection and close observation. Complete surgical resection of all sites of disease remains essential to survival: patients unable to achieve complete remission have a catastrophic overall survival rate. The role of second-line chemotherapy is not at all clear, and no controlled studies are available on this topic. It is worth considering for patients unable to achieve complete surgical remission, and those with multiple metastases and/or a RFI <24 months. Given their dismal prognosis, patients with multiple sites of disease not amenable to complete surgical resection should also be considered for innovative therapeutic approaches.

TH1579, MTH1 inhibitor, delays tumour growth and inhibits metastases development in osteosarcoma model

Background

Osteosarcoma (OS) is the most common primary malignant bone tumour. Unfortunately, no new treatments are approved and over the last 30 years the survival rate remains only 30% at 5 years for poor responders justifying an urgent need of new therapies. The Mutt homolog 1 (MTH1) enzyme prevents incorporation of oxidized nucleotides into DNA and recently developed MTH1 inhibitors may offer therapeutic potential as MTH1 is overexpressed in various cancers.

Methods

The aim of this study was to evaluate the therapeutic benefits of targeting MTH1 with two chemical inhibitors, TH588 and TH1579 on human osteosarcoma cells. Preclinical efficacy of TH1579 was assessed in human osteosarcoma xenograft model on tumour growth and development of pulmonary metastases.

Findings

MTH1 is overexpressed in OS patients and tumour cell lines, compared to mesenchymal stem cells. In vitro, chemical inhibition of MTH1 by TH588 and TH1579 decreases OS cells viability, impairs their cell cycle and increases apoptosis in OS cells. TH1579 was confirmed to bind MTH1 by CETSA in OS model. Moreover, 90 mg/kg of TH1579 reduces in vivo tumour growth by 80.5% compared to non-treated group at day 48. This result was associated with the increase in 8-oxo-dG integration into tumour cells DNA and the increase of apoptosis. Additionally, TH1579 also reduces the number of pulmonary metastases.

Interpretation

All these results strongly provide a pre-clinical proof-of-principle that TH1579 could be a therapeutic option for patients with osteosarcoma.

Funding

This study was supported by La Ligue Contre le Cancer, la SFCE and Enfants Cancers Santé.

NFIL3 Acts as a Nuclear Factor to Increase Osteosarcoma Progression

Purpose

Osteosarcoma is one of the most common primary malignant, aggressive bone neoplasms. However, the mechanisms of osteosarcoma proliferation, migration, and invasion are not well understood. To explore the possible mechanism of osteosarcoma progression, we used a public database for gene analysis to identify the possible factors that are important in osteosarcoma progression. Nuclear factor interleukin 3 (NFIL3) regulated was highly expressed in sarcoma tissues. In this study, we meant to probe the function of NFIL3 in osteosarcoma proliferation, migration, and invasion.

Methods

The expression of NFIL3 in osteosarcoma tissues was analysed via RT-PCR and immunohistochemistry staining. In order to elucidate the function of NFIL3 in osteosarcoma, we performed cell growth assays and colony formation assays to explore the role of NFIL3 in proliferation in osteosarcoma cells. Futhermore, we analysed osteosarcoma cell migration and invasion via wound healing assays and transwell migration and invasion assays.

Results

NFIL3 is overexpressed in osteosarcoma tissues; 15 of the 20 osteosarcoma tissues analysed highly expressed NFIL3. Our in vitro experiments confirmed that NFIL3 promoted the proliferation of M6-63 and SaOS2 cells (P < 0.01). In addition, NFIL3 promoted the migration and invasion of osteosarcoma cells (P < 0.05).

Conclusion

NFIL3 is highly expressed in osteosarcoma tissues and thus promotes the proliferation, migration, and invasion of osteosarcoma cells. NFIL3 is potential to become a new target for development of novel treatment strategies of osteosarcoma.

In Vitro Generation of Anti-Osteosarcoma Cytotoxic Activity Using Dendritic Cells Loaded with Heat Shock Protein 70-Peptide Complexes

Introduction: This study aimed at evaluating the anti-osteosarcoma activity of cytotoxic T lymphocytes (CTLs) induced by dendritic cells (DCs) pulsed with heat shock protein 70-peptide complexes (Hsp70-PCs). Materials and methods: Human recombinant Hsp70 expression was analyzed using thin layer scanning and Western blot assay. Tumor antigens from Saos-2 cells were extracted to reconstitute Hsp70-PCs. Maturation of cord blood-derived DC was evaluated by alkaline phosphatase-anti-alkaline phosphatase kit and inverted microscope. The anti-osteosarcoma activity of CTLs evoked by DCs loaded with Hsp70-PCs was determined using Thiazolyl Blue Tetrazolium Bromide (MTT) assay. Results: Hsp70 protein level in BL21 (DE3) increased in a time-dependent manner after induction. The expression of surface markers was upregulated and a typical dendritic morphology was observed in mature DCs. Allogeneic CTLs exhibited strong cytotoxic activity against Saos-2 cells. Conclusion: Our in vitro experiment demonstrated the potent induction of cytotoxic activity against osteosarcoma using DC-based vaccine loaded with Hsp70-PCs.

KLF4 functions as an oncogene in promoting cancer stem cell-like characteristics in osteosarcoma cells

Despite more effective chemotherapy combined with limb-salvage surgery for the osteosarcoma treatment, survival rates for osteosarcoma patients have stagnated over the past three decades due to the poor prognosis. Osteosarcoma cancer stem cells (OSCs) are responsible for the growth and metastasis of osteosarcoma. The existence of OSCs offers a theoretical explanation for therapeutic failures including tumor recurrence, metastasis, and drug resistance. Understanding the pathways that regulate properties of OSCs may shed light on mechanisms that lead to osteosarcoma and suggest better modes of treatment. In this study, we showed that the expression level of Kruppel-like factor 4 (KLF4) is highly associated with human osteosarcoma cancer stemness. KLF4-overexpressed osteosarcoma cells displayed characteristics of OSCs: increased sphere-forming potential, enhanced levels of stemness-associated genes, great chemoresistance to adriamycin and CDDP, as well as more metastasis potential. Inversely, KLF4 knockdown could reduce colony formation in vitro and inhibit tumorigenesis in vivo, supporting an oncogenic role for KLF4 in osteosarcoma pathogenesis. Furthermore, KLF4 was shown to activate the p38 MAPK signaling pathway to promote cancer stemness. Altogether, our studies uncover an essential role for KLF4 in regulation of OSCs and identify KLF4-p38 MAPK axis as a potential therapeutic target for osteosarcoma treatment.

miR-363 acts as a tumor suppressor in osteosarcoma cells by inhibiting PDZD2

PDZ domain containing 2 (PDZD2) is a multi-PDZ domain protein that promotes the proliferation of insulinoma cells, and is upregulated during prostate tumorigenesis. However, the function of PDZD2 in other cancers, including osteosarcoma (OS), remains unclear. Dysregulation of microRNAs (miRNAs) contributes to tumor initiation, proliferation and metastasis, via the regulation of their target genes. The present study investigated the functions of miR-363 and PDZD2 in MG-63 OS cells. The results revealed that MG-63 cells contained low levels of miR-363, and that overexpression of miR-363 in MG-63 cells significantly inhibited the vitality, proliferation, and colony formation ability of the cells, but promoted their apoptosis and G1/S arrest by regulating proliferating cell nuclear antigen (PCNA) and caspase-3 expression. Additionally, miR-363 impaired the migration and invasion of MG-63 cells by regulating the epithelial-mesenchymal transition (EMT) phenotype. Notably, a bioinformatics analysis and luciferase reporter assay indicated that PDZD2 was a direct target of miR-363. miR-363 overexpression reduced PDZD2 protein levels and knockdown of PDZD2 suppressed the colony formation, migration and invasion of MG-63 cells, but promoted their apoptosis by regulating expression of PCNA, caspase-3, and the EMT phenotype. In vivo studies further confirmed that miR-363 functioned as tumor suppressor, by inhibiting tumor growth, promoting cell apoptosis, and reducing PDZD2 and PCNA levels and the prevalence of the EMT phenotype in tumor tissues. The present data demonstrated that downregulation of the tumor suppressor miR-363 may be involved in the development of osteosarcoma via regulation of PDZD2.

lncRNA SNHG1 negatively regulates miRNA‑101‑3p to enhance the expression of ROCK1 and promote cell proliferation, migration and invasion in osteosarcoma

Osteosarcoma (OS) is a rare malignant bone tumor that commonly occurs in children and adolescents and causes pain and swelling of the long bones of the legs and arms. Long non-coding RNA (lncRNA) and micro (mi)RNA-101 are important in the initialization and progression of OS. However, the mechanism underlying the role of the lncRNA and miRNA-101 in OS remains to be fully elucidated. In the present study, through reverse transcription-quantitative polymerase chain reaction analysis, it was first found that the lncRNA SNHG1 was upregulated and miRNA-101-3p was downregulated in OS tissues and cell lines. Second, the knockdown of lncRNA SNHG1 induced cell apoptosis and maintained the cell cycle at the G0/G1 phase, which decreased the overall cell viability. Furthermore, according to a dual-luciferase assay and western blot analysis, miRNA-101-3p was found to be a target of the lncRNA SNHG1 in OS, which further regulated the expression of Rho-associated coiled-coil-containing protein kinase 1 (ROCK1). It was found that the phosphoinositide 3-kinase/ATK pathway was inactivated and that epithelial-mesenchymal transition was activated in OS cell lines with overexpression of the lncRNA SNHG1. Taken together, in OS cell lines, the lncRNA SNHG1 acted as an oncogene, and miRNA-101-3p was considered a tumor suppressor. The lncRNA SNHG1 promoted OS cell proliferation, migration and invasion by downregulating the expression of miRNA-101-3p, which enhanced the expression of ROCK1.

Mitoxantrone induces apoptosis in osteosarcoma cells through regulation of the Akt/FOXO3 pathway

The outcome of chemotherapy for osteosarcoma have improved during the past decade and more patients have access to combination chemotherapy, but there has been no significant clinical progress in the patient survival rate. Recently, forkhead-box O3 (FOXO3) was identified as a pivotal transcription factor responsible for the transcriptional regulation of genes associated with suppression of cancer. The purpose of the present study was to screen small chemicals activating FOXO3 and elucidate their underlying mechanism. Using a drug discovery platform based on the phosphorylation status of FOXO3 in osteosarcoma cells, mitoxantrone (MTZ), a type of DNA-damaging agent, was selected as a possible FOXO3 activator from the food and drug administration-approved drug library. MTZ treatments significantly inhibited the phosphorylation level of Akt-pS473 and caused nuclear localization of FOXO3 in osteosarcoma cells. MTZ treatment inhibited proliferation in osteosarcoma cells in vitro, whereas silencing FOXO3 potently attenuates MTZ-mediated apoptosis in osteosarcoma cells. Taken together, the results indicated that MTZ induces apoptosis in osteosarcoma cells through an Akt/FOXO3-dependent mechanism.

Serum β-HCG and CA-125 as Tumor Markers in a Patient with Osteosarcoma: Case Report

Background

Elevated β-HCG serum levels are usually an indication of pregnancy or pregnancy-related disorders, but β-HCG can also be elevated in testis and germ cell tumors. HCG expression by osteosarcoma is a rare phenomenon, with a few documented cases. CA-125 is commonly used to monitor disease progression and treatment response in ovarian cancer. CA-125 expression in patients with osteosarcoma has not previously been documented.

Case report

Elevated β-HCG and CA-125 serum levels were observed in a female patient of 57 years of age with metastatic osteosarcoma during screening investigations prior to participation in a phase I clinical trial. Pregnancy was excluded. Immunohistochemical studies revealed the tumor to be the source of the elevated β-HCG serum levels. We found no CA-125 expression in tumor tissue. The patient was treated with E7080, a novel oral multi-targeted tyrosine kinase inhibitor. We measured serum β-HCG and CA-125 to monitor treatment response. She had a significant clinical and radiological response after two cycles of treatment, but developed progressive disease after the third cycle. The β-HCG serum levels seemed to better reflect her disease status than those of the other tumor marker, CA-125.

Conclusions

When elevated, β-HCG serum levels in patients with osteosarcoma might be used to monitor treatment. Treatment of advanced osteosarcoma with tyrosine kinase inhibitors, including E7080, warrants further investigation. Free full text available at www.tumorionline.it

The miR-17-92 cluster/QKI2/β-catenin axis promotes osteosarcoma progression

Quaking(QKI) is an RNA binding protein, and it has been shown to serve as a tumor suppressor. However, the expression and functions of QKI in osteosarcoma progression remain poorly understood. In this study, we aimed to explore the expression of QKI2 in osteosarcoma tissues and to determine the mechanisms underlying aberrant QKI2 expression and the effect of QKI2 on osteosarcoma progression. We found that QKI2 was significantly down-regulated in osteosarcoma tissues compared with adjacent normal bone tissues. Using a series of molecular biological techniques, we demonstrated that all members of the miR-17-92 cluster were up-regulated and contributed to the down-regulation of QKI2 expression in osteosarcoma. Functional examination showed that QKI2 inhibited the proliferation, migration and invasion of osteosarcoma cells via decreasing the expression of β-catenin. Conclusively, we revealed that the regulatory axis consisting of the miR-17-92 cluster/QKI2/β-catenin plays a crucial role in the development and progression of osteosarcoma.

Antitumor activity of resveratrol against human osteosarcoma cells: a key role of Cx43 and Wnt/β-catenin signaling pathway

Osteosarcoma is a high-grade bone sarcoma with strong invasive ability. However, treatment with traditional chemotherapeutic drugs is limited by low tolerability and side effects. Resveratrol has been reported previously to have selective antitumor effect on various tumor cells while little is known about its effects and underlying mechanism in osteosarcoma biology. In this study, we found that resveratrol inhibits proliferation and glycolysis, induces apoptosis and reduces the invasiveness of U2-OS cells in vitro. After treatment with resveratrol, the expression of related Wnt/β-catenin signaling pathway target genes, such as β-catenin, c-myc, cyclin D1, MMP-2 and MMP-9, was downregulated and an increased E-cadherin level was observed as well. Additionally, the dual luciferase assay results also indicated that resveratrol suppressed the activity of Wnt/β-catenin signaling pathway. Interestingly, we noticed that the expression of connexin 43 (Cx43) increased with the prolongation of resveratrol treatment time. To further investigate the relationship between Cx43 and the Wnt/β-catenin signaling pathway in osteosarcoma, we used lentiviral-mediated shRNA to knockdown the expression of Cx43. Knockdown of Cx43 activated the Wnt/β-catenin signaling pathway, promoted proliferation and invasion, and inhibited apoptosis of U2-OS cells. Taken together, our results demonstrate that the antitumor activity of resveratrol against U2-OS cells in vitro occurs through up-regulating Cx43 and E-cadherin, and suppressing the Wnt/β-catenin signaling pathway. Moreover, Cx43 expression is negatively related to the activity of the Wnt/β-catenin pathway in U2-OS cells.

Oxycodone Resistance Due to Rifampin Use in an Osteosarcoma Patient with Tuberculosis

BACKGROUND Oxycodone is a semisynthetic opioid receptor agonist, and is frequently used for pain control in patients with cancer. Most oxycodone is metabolized by N-demethylation to noroxycodone by CYP3A. Rifampin is a strong inducer of several drug-metabolizing enzymes, including CYP3A. Hence, rifampin-induced CYP3A activity may decrease the effect of oxycodone. CASE REPORT Osteosarcoma is a highly aggressive primary bone tumor of childhood and adolescence. Here, we report a 30-year-old male with osteosarcoma of the femur with lung metastases in the upper lobe. The lung also contained small, scattered nodular lesions that were identified as tuberculosis. Multi-drug therapy, including rifampin, was administered. The upper-lobe metastatic lesion extended to the brachial plexus and caused severe pain. Over 1000 mg per day of oxycodone was ineffective for pain control. However, morphine was able to control his pain at about one-third the equivalent dose. CONCLUSIONS Our patient demonstrated oxycodone resistance due to rifampin. Chemotherapy may have compromised the patient's immune system, thus theoretically increasing the risk of tuberculosis. Recognition of the interactions between rifampin and oxycodone is important in this and other cancers. Notably, for patients using high doses of oxycodone to manage severe pain, stopping rifampin may lead to oxycodone overdose.

Upregulation of long noncoding RNA Xist promotes proliferation of osteosarcoma by epigenetic silencing of P21

Recent studies show that lncRNAs involve in the initiation and progression of various cancers including osteosarcoma (OS). IncRNA Xist has been verified as an oncogene in several human cancers, and its abnormal expression was closely associated with tumor initiation and progression. Nevertheless, the role of Xist in OS remains unclear. Here, we revealed the Xist expression level was up-regulated in OS tissues and discovered that Xist knockdown significantly repressed OS cell proliferation. Additionally, mechanistic analysis revealed that Xist can repress P21 expression to regulate OS cell cycle and proliferation by binding to EZH2. Taking all into account, Xist may function in promoting OS cell proliferation and may potentially serve as a novel biomarker and therapeutic target for OS.

Mdm2 selectively suppresses DNA damage arising from inhibition of topoisomerase II independent of p53

Mdm2 is often overexpressed in tumors that retain wild-type TP53 but may affect therapeutic response independently of p53. Herein is shown that tumor cells with MDM2 amplification are selectively resistant to treatment with topoisomerase II poisons but not other DNA damaging agents. Tumor cells that overexpress Mdm2 have reduced DNA double-strand breaks in response to doxorubicin or etoposide. This latter result is not due to altered drug uptake. The selective attenuation of DNA damage in response to these agents is dependent on both Mdm2 levels and an intact ubiquitin ligase function. These findings reveal a novel, p53-independent activity of Mdm2 and have important implications for the choice of chemotherapeutic agents in the treatment of Mdm2-overexpressing tumors.

Effects of SOST Gene Silencing on Proliferation, Apoptosis, Invasion, and Migration of Human Osteosarcoma Cells Through the Wnt/β-Catenin Signaling Pathway

Our study explored the effects of SOST gene silencing on the proliferation, apoptosis, invasion, and migration of human osteosarcoma cells through Wnt/β-catenin signaling pathway. Fresh tissues were obtained from 108 patients with osteosarcoma and 46 patients with osteochondroma. Human osteosarcoma cells (MG-63, U2-OS, HOS, and Saos-2) and normal osteoblast (hFoB1.19) were selected and cultured. Osteosarcoma cells were grouped randomly into the blank group, the scrambled control group, and the SOST-siRNA group. Cell proliferation was determined by MTT assay. Cell cycle and apoptosis were tested by flow cytometry. Transwell and scratch test were performed to determine cell invasion and migration. The qRT-PCR and Western blotting were used to detect mRNA and protein expression level of sclerostin, Wnt1, β-catenin, C-Myc, Cyclin D1, and MMP-7. The activity of caspase-3 was assessed by immunocytochemistry. Alkaline phosphatase (ALP) activity was measured using P-nitrophenylphosphate as a substrate. Low SOST mRNA and sclerostin protein expression levels were observed in osteosarcoma tissues and cells. Compared with the blank and scrambled control groups, sclerostin expression, apoptotic cells, ALP activity, and caspase-3 activity were down-regulated, while the proliferation, invasion, and migration abilities of osteosarcoma cells were evidently enhanced in the SOST-siRNA group. After SOST gene silencing, the mRNA and protein expression levels of Wnt1, β-catenin, C-Myc, Cyclin D1, and MMP-7 in osteosarcoma cells and β-catenin protein expression levels in the nucleus and cytoplasm were significantly elevated. SOST gene silencing promotes the proliferation, invasion, and migration, and inhibits apoptosis of osteosarcoma cells by activating Wnt/β-catenin signaling pathway.

Structural analysis and magnetic induced hyperthermia of Fe3+and Mn2+substituted β-Ca3(PO4)2

Fe³⁺/Mn²⁺co-substitutions in β-Ca₃(PO₄)₂elicit a good hyperthermia effect and biocompatible features.

Resveratrol reverses P-glycoprotein-mediated multidrug resistance of U2OS/ADR cells by suppressing the activation of the NF-κB and p38 MAPK signaling pathways

The present study aimed to investigate the reversal effect of resveratrol on the phenomenon of multidrug resistance in U2OS/adriamycin (ADR) cells and to clarify the molecular mechanisms. To examine the cell survival and half-inhibitory concentration (IC50) of ADR in U2OS and U2OS/ADR cells, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used. The accumulation of ADR in U2OS and U2OS/ADR cells was investigated by flow cytometry. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were used to detect the expression of multidrug resistance protein 1 (MDR1), P-glycoprotein (P-gp), p65 and p38. Compared with U2OS cells, the IC50 value of ADR was significantly increased in U2OS/ADR cells, which exhibited high levels of MDR1/P-gp. However, resveratrol could drastically reduce the IC50 value of ADR and the expression of MDR1/P-gp, and increased the accumulation of ADR in U2OS/ADR cells. In addition, the expression levels of p38 (phosphorylated) and p65 (acetylated and total) in U2OS/ADR cells were also significantly suppressed by resveratrol. These results suggested that the nuclear factor (NF)-κB and p38 mitogen-activated protein kinase (MAPK) signaling pathways are correlated with ADR-induced drug resistance in U2OS/ADR cells. Furthermore, resveratrol could downregulate the expression of MDR1/P-gp and reverse the drug resistance phenomenon in U2OS/ADR cells partly at least by suppressing the activation of the NF-κB and p38 MAPK signaling pathways.

Celastrol negatively regulates cell invasion and migration ability of human osteosarcoma via downregulation of the PI3K/Akt/NF-κB signaling pathway in vitro

Osteosarcoma (OS) is a primary malignant tumor of the bone, with a tendency to metastasize early. Despite the advances in treatment options, more than 30% of patients develop distant metastases, and the prognosis of these patients with metastases is extremely poor. Celastrol has been demonstrated to manifest multiple pharmacological activities, including induction of apoptosis in numerous types of cancer cell lines. Our previous studies have also suggested that Celastrol is capable of inducing apoptosis of human osteosarcoma cells via the mitochondrial-dependent pathway. The purpose of this study was to investigate the effects of Celastrol on the migration and invasion of human osteosarcoma U-2OS cells in vitro. Cell migration and invasion were investigated using wound healing and Boyden chamber Transwell assays. We observed that Celastrol suppressed cell invasion and migration in human osteosarcoma U-2OS cells. Furthermore, protein expression levels of phosphorylated phosphatidylinositol 3-kinase (PI3K), Akt, inhibitor of κB kinase α/β, inhibitor of κB α, nuclear factor-κB (NF-κB subunit p65) and matrix metalloproteinase (MMP)-2 and -9 were measured by western blot analysis. We observed that the PI3K/Akt/NF-κB signaling pathway was inhibited following Celastrol treatment. In addition, the expression levels of MMP-2 and -9 proteins were also reduced significantly following Celastrol treatment. Therefore, we confirmed that Celastrol suppressed osteosarcoma U-2OS cell metastasis via downregulation of the PI3K/Akt/NF-κB signaling pathway in vitro.

Metastatic osteosarcoma: a challenging multidisciplinary treatment

Osteosarcoma is the most common malignant bone tumor, currently treated with pre-and postoperative chemotherapy in association with the surgical removal of the tumor. About 15-20% of patients have evidence of metastases at diagnosis, mostly in the lungs. Patients with metastatic disease still have a very poor prognosis, with approximately 20-30% of long-term survivors, as compared with 65-70% of patients with localized disease. The optimum management of these patients has not been standardized yet due to several patterns of metastatic disease harboring different prognosis. Complete surgical resection of all sites of disease is mandatory and predictive of survival. Patients with multiple sites of disease not amenable to complete surgery removal should be considered for innovative therapeutic approaches because of poor prognosis.

Blocking HSP90 Addiction Inhibits Tumor Cell Proliferation, Metastasis Development, and Synergistically Acts with Zoledronic Acid to Delay Osteosarcoma Progression

PURPOSE

Despite recent improvements in therapeutic management of osteosarcoma, ongoing challenges in improving the response to chemotherapy warrants the development of new strategies to improve overall patient survival. Among them, HSP90 is a molecular chaperone involved in the maturation and stability of various oncogenic proteins leading to tumor cells survival and disease progression. We assessed the antitumor properties of a synthetic HSP90 inhibitor, PF4942847, alone or in combination with zoledronic acid in osteosarcoma.

EXPERIMENTAL DESIGN

The effects of PF4942847 were evaluated on human osteosarcoma cells growth and apoptosis. Signaling pathways were analyzed by Western blotting. The consequence of HSP90 therapy combined or not with zoledronic acid was evaluated in mice bearing HOS-MNNG xenografts on tumor growth, associated bone lesions, and pulmonary metastasis. The effect of PF4942847 on osteoclastogenesis was assessed on human CD14(+) monocytes.

RESULTS

In osteosarcoma cell lines, PF4942847 inhibited cell growth in a dose-dependent manner (IC50 ±50 nmol/L) and induced apoptosis with an increase of sub-G1 fraction and cleaved PARP. These biologic events were accompanied by decreased expression of Akt, p-ERK, c-Met, and c-RAF1. When administered orally to mice bearing osteosarcoma tumors, PF4942847 significantly inhibited tumor growth by 80%, prolonged survival compared with controls, and inhibited pulmonary metastases by blocking c-Met, FAK, and MMP9 signaling. In contrast to 17-allylamino-17-demethoxygeldanamycin (17-AAG), PF4942847 did not induce osteoclast differentiation, and synergistically acted with zoledronic acid to delay osteosarcoma progression and prevent bone lesions.

CONCLUSIONS

All these data provide a strong rationale for clinical evaluation of PF4942847 alone or in combination with zoledronic acid in osteosarcoma. Clin Cancer Res; 22(10); 2520-33. ©2015 AACR.

MicroRNA-150 functions as a tumor suppressor in osteosarcoma by targeting IGF2BP1

Osteosarcoma (OS) is the most common primary malignant bone tumor with high morbidity in young adults and adolescents. Increasing evidence has demonstrated that aberrant microRNA (miRNA) expression is involved in OS occurrence and development. miR-150 has been recently widely studied in many cancers, but not including OS. This study is aimed to investigate the expression and biological role of miR-150 in OS. Here, we found that miR-150 expression was consistently downregulated in OS tissues and cell lines compared with the matched adjacent normal tissues and human normal osteoblast cells (NHOst), and its expression was significantly correlated with lymph node metastasis and tumor-node-metastasis (TNM) stage. Functional study showed that restoration of miR-150 expression in OS cells could inhibit cell proliferation, migration, and invasion and induced apoptosis in vitro as well as suppressed tumor growth of OS in vivo. Mechanistically, IGF2 mRNA-binding protein 1(IGF2BP1) was confirmed to act as a direct target of miR-150, and the IGF2BP1 mRNA expression was inversely correlated with the level of miR-150 in OS tissues. In addition, downregulation of endogenous IGF2BP1 exhibited similar effects of overexpression of miR-150. Taken together, these findings suggest that miR-150 functions as a tumor suppressor in OS partially by targeting IGF2BP1.

Mitogen-activated protein kinase 7 promotes cell proliferation, migration and invasion in SOSP-M human osteosarcoma cell line

PURPOSE

Osteosarcoma (OS) is the most common primary bone tumor and has low cure rates. Our study aimed to evaluate the roles of mitogen-activated protein kinase 7 (MAPK7) in cell proliferation, migration and invasion using the SOSP-M human OS cell line as an in vitro model.

METHODS

SOSP-M cells were transfected with PCDNA3.1-MAPK7 and siRNA-MAPK7 plasmids using Lipofectamine 2000. Quantitative real-time polymerase chain reaction (RT-PCR) was performed to determine the relative expression level of MAPK7 and Western blot analysis was carried out to determine the expression level of ERK5 protein. Then MTT, scratch wound healing and Matrigel transwell assays were used to investigate the roles of MAPK7 expression in the proliferation, migration and invasion, respectively, of SOSP-M cells in vitro.

RESULTS

RT-PCR analysis showed that the expression level of MAPK7 increased significantly after transfection with PCDNA3.1-MAPK7 plasmid compared with the blank group, while it decreased significantly after transfection with siRNA-MAPK7 plasmid. Similar results for ERK5 expression were obtained by Western blot analysis. In addition, the cell proliferation rate, cell migration rate and invasive cell number in the PCDNA3.1-MAPK7 transfection group increased significantly compared with the blank group, while they decreased significantly in the siRNA-MAPK7 transfection group.

CONCLUSIONS

Our results indicate that overexpression of MAPK7 in human OS cells could promote cell proliferation, migration and invasion, whereas knockdown of MAPK7 expression had the opposite effect. All the results suggest that MAPK7 may serve as a potent target for drug development.

Clusterin inhibition using OGX-011 synergistically enhances zoledronic acid activity in osteosarcoma

Purpose

Despite recent improvements in therapeutic management of osteosarcoma, ongoing challenges in improving the response to chemotherapy warrants new strategies still needed to improve overall patient survival. Among new therapeutic approaches, zoledronic acid (ZOL) represents a promising adjuvant molecule to chemotherapy to limit the osteolytic component of bone tumors. However, ZOL triggers the elevation of heat shock proteins (Hsp), including Hsp27 and clusterin (CLU), which could enhance tumor cell survival and treatment resistance. We hypothesized that targeting CLU using siRNA or the antisense drug, OGX-011, will suppress treatment-induced CLU induction and enhance ZOL-induced cell death in osteosarcoma (OS) cells.

Methods

The combined effects of OGX-011 and ZOL were investigated in vitro on cell growth, viability, apoptosis and cell cycle repartition of ZOL-sensitive or -resistant human OS cell lines (SaOS2, U2OS, MG63 and MNNG/HOS).

Results

In OS cell lines, ZOL increased levels of HSPs, especially CLU, in a dose- and time-dependent manner by mechanism including increased HSF1 transcription activity. The OS resistant cells to ZOL exhibited higher CLU expression level than the sensitive cells. Moreover, CLU overexpression protects OS sensitive cells to ZOL-induced cell death by modulating the MDR1 and farnesyl diphosphate synthase expression. OGX-011 suppressed treatment-induced increases in CLU and synergistically enhanced the activity of ZOL on cell growth and apoptosis. These biologic events were accompanied by decreased expression of HSPs, MDR1 and HSF1 transcriptional activity. In vivo, OGX-011, administered 3 times a week (IP, 20mg/kg), potentiated the effect of ZOL (s.c; 50μg/kg), significantly inhibiting tumor growth by 50% and prolonging survival in MNNG/HOS xenograft model compared to ZOL alone.

Conclusion

These results indicate that ZOL-mediated induction of CLU can be attenuated by OGX-011, with synergistic effects on delaying progression of osteosarcoma.

The role of chemotherapy for metastatic, relapsed and refractory osteosarcoma

Despite a large number of publications on outcomes of second-line chemotherapy for osteosarcoma, there is little consensus on efficacy of the therapy.

OBJECTIVE

Our objective was to systematically categorize published evidence for chemotherapy for metastatic, relapsed and refractory osteosarcoma in order to provide an updated and comprehensive analysis of the clinical outcomes.

METHODS

We performed a search of PubMed and EMBASE to identify published articles reporting on validated clinical outcomes measures (the rate of complete response [CR] and partial response [PR], the rate of stable disease [SD] and progressive disease [PD] and the 5-year overall survival) after chemotherapy in patients with metastatic, relapsed and refractory osteosarcoma. A total of 20 articles were identified and stratified by different regimens. Finally, six regimens that have at least two drugs were reviewed. Weighted averages of each outcome were computed.

RESULTS

The weighted average overall response rate (CR + PR) for the combination of ifosfamide, etoposide and high-dose methotrexate therapy was 62 %, and the tumor control rate (CR + PR + SD) was 92.3 %; the highest of all six regimens. The weighted average overall response rate and tumor control rate of ifosfamide-etoposide therapy (41.7 and 77.9 %, respectively) were the highest of the two-drug regimens. Weighted average overall response rate and tumor control rate for the remaining regimens were 20.5 and 56.8 %, respectively, for cyclophosphamide-etoposide; 30.0 and 73.5 % for ifosfamide, carboplatin, and etoposide; 12.0 and 40.0 % for cyclophosphamide-topotecan; and 14.5 and 36.4 % for gemcitabine-docetaxel.

CONCLUSION

A chemotherapy regimen comprising both a cell cycle-specific drug and a cell cycle-nonspecific drug could increase response rates. The combination of ifosfamide and etoposide therapy is our first choice in two-drug regimens. Regarding three-drug regimens, adding a cell cycle-specific drug to ifosfamide-etoposide therapy may result in a better response rate than adding a cell cycle-nonspecific drug, or any other two-drug regimens in current studies. Hence, we recommend the use of second-line chemotherapy based on the combination ifosfamide-etoposide regimen in patients with metastatic, relapsed and refractory osteosarcoma.

Individualized chemotherapy for osteosarcoma and identification of gene mutations in osteosarcoma

The study aims to identify novel gene mutations in osteosarcoma and to guide individualized preoperative chemotherapy for osteosarcoma based on the analysis of expression and mutations of the drug-metabolism-related genes. Twenty-eight osteosarcoma patients received individualized preoperative chemotherapy regimens. Expression levels and mutations of chemotherapy-related genes in samples collected from the patients were determined using real-time PCR and DNA sequencing, respectively. Patient sensitivity to chemotherapeutic agents was evaluated by systematic analysis of the PCR and sequencing results. Novel mutations were identified via high-throughput sequencing of 339 genes in 10 osteosarcoma samples. Individualized preoperative chemotherapy outcomes were valid for nine patients (n = 9/28, 32.1%). Chemosensitivity assays showed that all 28 patients were sensitive to ifosfamide, whereas 46.4 and 39.2% were sensitive to docetaxel and platinum, respectively. More importantly, patients receiving highly chemosensitive chemotherapy agents had better prognosis and treatment outcomes than those receiving less chemosensitive agents (P < 0.05). In addition, 39 gene mutations were detected in at least five osteosarcoma tumor samples. Analysis of the expression and mutation of drug-metabolism-related genes will aid in the design of effective individualized preoperative chemotherapy regimens for osteosarcoma. Determining the chemosensitivity of individual tumors to chemotherapeutic agents will facilitate the development of better therapeutic approaches. Individualized treatment of osteosarcoma may improve chemotherapy efficacy and the survival rate of osteosarcoma patients. High-throughput genotyping allows mapping of osteosarcoma mutations, and novel gene mutations offered new candidates for diagnosis and therapeutic targeting.

Silencing of galectin-3 represses osteosarcoma cell migration and invasion through inhibition of FAK/Src/Lyn activation and β-catenin expression and increases susceptibility to chemotherapeutic agents

Galectin-3 is involved in tumor cell proliferation, adhesion, angiogenesis and metastasis. Galectin-3 promotes β-catenin/Wnt signaling, and β-catenin-related oncogenesis has been frequently reported in osteosarcoma. However, the correlation between galectin-3 and β‑catenin signaling in osteosarcoma is poorly defined. We hypothesized that galectin-3 may control the migration and invasion of cancer cells and that silencing of galectin-3 would therefore, suppress motility in osteosarcoma cells. In the present study, we show that galectin-3 silencing in cultured human osteosarcoma cells had decreased cell migration and invasion capabilities; reduced the expression and activation of FAK, Src, Lyn, PI3K/Akt, ERK1/2 and β-catenin, which are key mediators of invasion; inhibited the expression and secretion of VEGF, MCP-1, IL-8, IL-6, MMP2/9 and phospho-Stat3; and potentiated sensitivity to cisplatin. Our results suggest that galectin-3 may be a feasible therapeutic target for osteosarcoma.

Conjugation of amino-bioactive glasses with 5-aminofluorescein as probe molecule for the development of pH sensitive stimuli-responsive biomaterials

Bioceramics, such as silica-based glasses, are widely used in bone and teeth restoration. Nowadays, the association between nanotechnology and pharmacology is one of the most promising research fields in cancer therapy. The advanced processing methods and new chemical strategies allow the incorporation of drugs within them or on their functionalized surfaces. Bioceramics can act as local drug delivery systems to treat bone and teeth diseases. The present paper reports data related to the development of a pH-stimuli responsive bioactive glass. The glass conjugation with 5-aminofluorescein (5-AF), through a pH-sensitive organic spacer, allows to produce a pH-responsive bioactive biomaterial: when it is exposed to specific pH changes, it can favour the release of 5-AF directly at the target site. 5-AF has been chosen as a simple, low cost, non toxic model to simulate doxorubicin, an anticancer drug. As doxorubicin, 5-AF contains an amino group in its structure in order to form an amide bond with the carboxylic functionalities of the glass. Raman spectroscopy and thermal analysis confirm the glass conjugation of 5-AF by means of an amide bond; the amount of 5-AF loaded was very high (≈ 65 and 44 wt%). The release tests at two different pH (4.2 and 7.4) show that the amount of released 5-AF is higher at acid pH with respect to physiological one. This preliminary datum evidenced that a pH-sensitive drug delivery system has been developed. The low amount of 5-AF released (<1 wt% of the total 5-AF) is due to the very low solubility of 5-AF in aqueous medium. This disadvantage, may be overcome in a dynamic environment (physiological conditions), where it is possible to obtain a drug release system ensuring an effective therapeutic dose for long times and, at the same time, avoiding the drug toxicity.

Glucocorticoid receptor DNA binding factor 1 expression and osteosarcoma prognosis

Glucocorticoid receptor DNA binding factor 1 (GRF-1) is an important Rho family GTPase-activating protein, and the dysregulation of GRF-1 expression maybe involved in tumor progression. However, the role of GRF-1 expression in the osteosarcoma prognosis has been well less elaborated. Here, we conducted a hospital-based case study, including 247 patients with pathologically confirmed osteosarcoma to evaluate the associations between GRF-1 expression and osteosarcoma prognosis. We found that high GRF-1 expression was correlated with poor outcome of osteosarcoma compared with low GRF-1 expression (the median recurrence-free survival times, 11 months vs 56 months; the median overall survival times, 18 months vs 53 months). Like tumor stage, the GRF-1 expression was an independent prognostic factor influencing the survival of osteosarcoma [hazard ratio values (95 % confidence interval) were 5.39 (3.54-8.20) for recurrence-free survival (RFS) and 6.58 (4.44-9.74) for overall survival (OS), respectively]. Furthermore, the high expression of GRF-1 was significantly associated with larger tumor size, tumor dedifferentiation, and increasing metastasis risk. Functionally, the knockdown of GRF-1 expression inhibited tumor cells proliferation and induced cell apoptosis. These results indicate for the first time that GRF-1 expression may modify osteosarcoma prognosis and may be a potential tumor therapeutic target.

Rho GTPase-activating protein 35 rs1052667 polymorphism and osteosarcoma risk and prognosis

The Rho GTPase-activating protein 35 (ARHGAP35), an important Rho family GTPase-activating protein, may be associated with tumorigenesis of some tumors. Here, we investigated the relationship between an important polymorphic variant at 3′-UTR of this gene (rs1052667) and osteosarcoma risk and prognosis. This hospital-based case-control study, including 247 osteosarcoma patients and 428 age-, sex-, and race-matched healthy controls, was conducted in Guangxi population. Genotypes were tested using TaqMan PCR technique. We found a significant difference in the frequency of rs1052667 genotypes between cases and controls. Compared with the homozygote of rs1052667 C alleles (rs1052667-CC), the genotypes with rs1052667 T alleles (namely, rs1052667-CT or -TT) increased osteosarcoma risk (odds ratios: 2.41 and 7.35, resp.). Moreover, rs1052667 polymorphism was correlated with such pathological features of osteosarcoma as tumor size, tumor grade, and tumor metastasis. Additionally, this polymorphism also modified the overall survival and recurrence-free survival of osteosarcoma cases. Like tumor grade, ARHGAP35 rs1052667 polymorphism was an independent prognostic factor influencing the survival of osteosarcoma. These results suggest that ARHGAP35 rs1052667 polymorphism may be associated with osteosarcoma risk and prognosis.

Prognostic significance of HLA EMR8-5 immunohistochemically analyzed expression in osteosarcoma

Background

Defects in Human Leukocyte Antigen (HLA) class I antigen expression and/or function in tumor cells have been extensively investigated, because of their potential role in the escape of tumor cells from T cell recognition and destruction. The researchers evaluated HLA class I expression in tumor tissue as a prognostic factor in osteosarcoma patients and as a predictor of their survival. This retrospective cohort study was conducted at the pathology laboratory of Ain Shams University Hospital, and Ain Shams University Specialized Hospital during the period between January 2009 and January 2012.

Methods

The researchers investigated HLA class I expression in primary osteosarcoma by immunohistochemistry using EMR8-5 mAbs. Furthermore, researchers evaluated the correlation between HLA class I expression and the clinicopathological status and outcome in formalin fixed paraffin embedded tissues from thirty six (36) patients with osteosarcoma.

Results

A high expression of HLA class I was detected in 18 (50) % of tumor samples examined; while tumors with low or negative expression represented 9 (25%) cases each. Data indicate that the overall survival rate of patients with tumors highly expressing HLA class I was significantly higher than those with low or negative expression.

Conclusion

Down-regulation of class I antigen expression is associated with features of aggressive disease and a poorer prognosis. Therefore, it is imperative to identify HLA as a prognostic factor at the time of diagnosis to detect chemotherapy-resistant tumors and to generate a modified treatment regimen.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1159334857109547.

Current therapeutic strategies and novel approaches in osteosarcoma

Osteosarcoma is the most frequent malignant primary bone tumor and a main cause of cancer-related death in children and adolescents. Although long-term survival in localized osteosarcoma has improved to about 60% during the 1960s and 1970s, long-term survival in both localized and metastatic osteosarcoma has stagnated in the past several decades. Thus, current conventional therapy consists of multi-agent chemotherapy, surgery and radiation, which is not fully adequate for osteosarcoma treatment. Innovative drugs and approaches are needed to further improve outcome in osteosarcoma patients. This review describes the current management of osteosarcoma as well as potential new therapies.

Chemical constituents of volatile oil from Pyrolae herba and antiproliferative activity against SW1353 human chondrosarcoma cells

The objective of the present study was to identify chemical constituents of volatile oil from Pyrolae herba (PHVO) and evaluate the antiproliferative activity of PHVO against SW1353 human chondrosarcoma cells. The volatile oil from Pyrolae herba was prepared by hydrodistillation and characterized by gas chromatography-mass spectroscopy (GC-MS). A total of 12 components in PHVO were identified representing 81.62% of the total integrated chromatographic peaks. The major compounds were found to be n-hexadecanoic acid (29.29%), cedrol (17.08%), 6,10,14-trimethyl-2-pentadecanone (9.59%) and cis-9-octadecadienoic acid (8.23%). The antiproliferative activity of PHVO against SW1353 cells was investigated using MTT assay, flow cytometry and western blot analysis. Our results demonstrated that PHVO inhibited SW1353 cell viability in a dose- and time-dependent manner. Furthermore, PHVO treatment decreased the number of cells entering the S phase and caused a reduction in the expression of cyclin D1, cyclin-dependent kinase (CDK)4 and CDK6, whereas it caused an increase in the expression of p21. PHVO demonstrated potent antitumor activity against SW1353 cells, suggesting its potential use as a therapeutic agent in the treatment of chondrosarcoma.

Genetically engineered mouse models and human osteosarcoma

Osteosarcoma is the most common form of bone cancer. Pivotal insight into the genes involved in human osteosarcoma has been provided by the study of rare familial cancer predisposition syndromes. Three kindreds stand out as predisposing to the development of osteosarcoma: Li-Fraumeni syndrome, familial retinoblastoma and RecQ helicase disorders, which include Rothmund-Thomson Syndrome in particular. These disorders have highlighted the important roles of P53 and RB respectively, in the development of osteosarcoma. The association of OS with RECQL4 mutations is apparent but the relevance of this to OS is uncertain as mutations in RECQL4 are not found in sporadic OS. Application of the knowledge or mutations of P53 and RB in familial and sporadic OS has enabled the development of tractable, highly penetrant murine models of OS. These models share many of the cardinal features associated with human osteosarcoma including, importantly, a high incidence of spontaneous metastasis. The recent development of these models has been a significant advance for efforts to improve our understanding of the genetics of human OS and, more critically, to provide a high-throughput genetically modifiable platform for preclinical evaluation of new therapeutics.