Advances in emerging drugs for osteosarcoma

Blocking CXCR4-CARM1-YAP axis overcomes osteosarcoma doxorubicin resistance by suppressing aerobic glycolysis

Osteosarcoma, recognized for its aggressiveness and resistance to chemotherapy, notably doxorubicin, poses significant treatment challenges. This comprehensive study investigated the CXCR4-CARM1-YAP signaling axis and its pivotal function in controlling aerobic glycolysis, which plays a crucial role in doxorubicin resistance. Detailed analysis of Dox-resistant 143b/MG63-DoxR cells has uncovered the overexpression of CXCR4. Utilizing a combination of molecular biology techniques including gene silencing, aerobic glycolysis assays such as Seahorse experiments, RNA sequencing, and immunofluorescence staining. The study provides insight into the mechanistic pathways involved. Results demonstrated that disrupting CXCR4 expression sensitizes cells to doxorubicin-induced apoptosis and alters glycolytic activity. Further RNA sequencing revealed that CARM1 modulated this effect through its influence on glycolysis, with immunofluorescence of clinical samples confirming the overexpression of CXCR4 and CARM1 in drug-resistant tumors. Chromatin immunoprecipitation studies further highlighted the role of CARM1, showing it to be regulated by methylation at the H3R17 site, which in turn affected YAP expression. Crucially, in vivo experiments illustrated that CARM1 overexpression could counteract the tumor growth suppression that resulted from CXCR4 inhibition. These insights revealed the intricate mechanisms at play in osteosarcoma resistance to doxorubicin and pointed toward potential new therapeutic strategies that could target this metabolic and signaling network to overcome drug resistance and improve patient outcomes.

Cyclin L1 participates in Adriamycin resistance and progression of osteosarcoma via PI3K/AKT-mTOR pathway

Chemoresistance is a common and thorny problem in the treatment of osteosarcoma (OS), which obstructs the response of relapse or metastasis of OS to chemotherapy and leads to the unfavorable prognosis of OS patients. Cyclin L1 (CCNL1) is a non-canonical cyclin that plays an important role in the regulation of tumor cell proliferation and lymph node metastasis. In this work, we explored the impact of CCNL1 expression levels on proliferation, migration, and Adriamycin (ADM) resistance in OS and related mechanisms. We found that CCNL1 expression levels were significantly associated with clinical prognosis of patients with OS and CCNL1 could promote OS proliferation and migration. In addition, we also revealed that cellular CCNL1 was significantly increased in ADM-resistant OS cells and promoted ADM resistance. The PI3K/AKT-mTOR pathway is involved in CCNL1-mediated ADM resistance in OS. In summary, CCNL1 is involved in the progression of ADM resistance and OS through the PI3K/AKT-mTOR pathway, which will provide a new clue to the mechanism of ADM resistance and a potential target for the treatment of ADM-resistant OS.

Current approaches in tissue engineering-based nanotherapeutics for osteosarcoma treatment

Osteosarcoma (OS) is a malignant bone neoplasm plagued by poor prognosis. Major treatment strategies include chemotherapy, radiotherapy, and surgery. Chemotherapy to treat OS has severe adverse effects due to systemic toxicity to healthy cells. A possible way to overcome the limitation is to utilize nanotechnology. Nanotherapeutics is an emerging approach in treating OS using nanoparticulate drug delivery systems. Surgical resection of OS leaves a critical bone defect requiring medical intervention. Recently, tissue engineered scaffolds have been reported to provide physical support to bone defects and aid multimodal treatment of OS. These scaffolds loaded with nanoparticulate delivery systems could also actively repress tumor growth and aid new bone formation. The rapid developments in nanotherapeutics and bone tissue engineering have paved the way for improved treatment efficacy for OS-related bone defects. This review focuses on current bifunctional nanomaterials-based tissue engineered (NTE) scaffolds that use novel approaches such as magnetic hyperthermia, photodynamic therapy, photothermal therapy, bioceramic and polymeric nanotherapeutics against OS. With further optimization and screening, NTE scaffolds could meet clinical applications for treating OS patients.

Overexpression of miR-506-3p reversed doxorubicin resistance in drug-resistant osteosarcoma cells

Background and objective: Osteosarcoma is a common primary malignant tumor of bone, and doxorubicin is one of the most widely used therapeutic drugs. While the problem of doxorubicin resistance limits the long-term treatment benefits in osteosarcoma patients. The role of miRNAs and their target genes in osteosarcoma have become increasingly prominent. Currently, there is no report on miR-506-3p reversing doxorubicin resistance by targeting STAT3 in osteosarcoma. The purpose of this study was to investigate the molecular mechanism that overexpression of miR-506-3p reverses doxorubicin resistance in drug-resistant osteosarcoma cells. Methods: Doxorubicin-resistant osteosarcoma cells (U-2OS/Dox) were constructed by intermittent stepwise increasing stoichiometry. The target genes of miR-506-3p were predicted by bioinformatics approach and the targeting relationship between miR-506-3p and STAT3 was detected using dual luciferase reporter assay. U-2OS/Dox cells were treated with miR-506-3p overexpression and STAT3 silencing respectively. Then Western blot and RT-qPCR were used to detect the protein and mRNA expression levels of JAK2/STAT3 signaling pathway, drug-resistant and apoptotic associated molecules. The migration and invasion were assessed by cell scratch assay and transwell assay. The cell proliferative viability and apoptosis were investigated by CCK8 assay and flow cytometry assay. Results: U-2OS/Dox cells were successfully constructed with a 14.4-fold resistance. MiR-506-3p is directly bound to the 3'-UTR of STAT3 mRNA. Compared with U-2OS cells, the mRNA expression of miR-506-3p was reduced in U-2OS/Dox cells. Overexpression of miR-506-3p decreased the mRNA expression levels of JAK2, STAT3, MDR1/ABCB1, MRP1/ABCC1, Survivin and Bcl-2, and decreased the protein expression levels of p-JAK2, STAT3, MDR1/ABCB1, MRP1/ABCC1, Survivin and Bcl-2, and conversely increased Bax expression. It also inhibited the proliferation, migration and invasion of U-2OS/Dox cells and promoted cells apoptosis. The results of STAT3 silencing experiments in the above indicators were consistent with that of miR-506-3p overexpression. Conclusion: Overexpression of miR-506-3p could inhibit the JAK2/STAT3 pathway and the malignant biological behaviors, then further reverse doxorubicin resistance in drug-resistant osteosarcoma cells. The study reported a new molecular mechanism for reversing the resistance of osteosarcoma to doxorubicin chemotherapy and provided theoretical support for solving the clinical problems of doxorubicin resistance in osteosarcoma.

Development of a novel vasculogenic mimicry-associated gene signature for the prognostic assessment of osteosarcoma patients

BACKGROUND

Osteosarcoma (OS) is a form of primary bone malignancy associated with poor prognostic outcomes. Recent work has highlighted vasculogenic mimicry (VM) as a key mechanism that supports aggressive tumor growth. The patterns of VM-associated gene expression in OS and the relationship between these genes and patient outcomes, however, have yet to be defined.

METHODS

Here, 48 VM-related genes were systematically assessed to examine correlations between the expression of these genes and OS patient prognosis in the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) cohort. Patients were classified into three OS subtypes. Differentially expressed genes for these three OS subtypes were then compared with hub genes detected in a weighted gene co-expression network analysis, leading to the identification of 163 overlapping genes that were subject to further biological activity analyses. A three-gene signature (CGREF1, CORT, and GALNT14) was ultimately constructed through a least absolute shrinkage and selection operator Cox regression analysis, and this signature was used to separate patients into low- and high-risk groups. The K-M survival analysis, receiver operating characteristic analysis, and decision curve analysis were adopted to evaluate the prognostic prediction performance of the signature. Furthermore, the expression patterns of three genes derived from the prognostic model were validated by quantitative real-time polymerase chain reaction (RT-qPCR).

RESULTS

VM-associated gene expression patterns were successfully established, and three VM subtypes of OS that were associated with patient prognosis and copy number variants were defined. The developed three-gene signature was constructed, which served as independent prognostic markers and prediction factors for the clinicopathological features of OS. Finally, lastly, the signature may also have a guiding effect on the sensitivity of different chemotherapeutic drugs.

CONCLUSION

Overall, these analyses facilitated the development of a prognostic VM-associated gene signature capable of predicting OS patient outcomes. This signature may be of value for both studies of the mechanistic basis for VM and clinical decision-making in the context of OS patient management.

3-AP inhibits the growth of human osteosarcoma by decreasing the activity of the iron-dependent pathway

3-aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP) has broad-spectrum antitumor activity. However, its role in osteosarcoma (OS) remains unclear. Therefore, this study explored the effects of 3-AP on OS in vitro and in vivo using three human OS cell lines (MG-63, U2-OS, and 143B) and a nude mice model generated by transplanting 143B cells. The cells and mice were treated with DMSO (control) or gradient concentrations of 3-AP. Then, various assays (e.g., cell counting kit-8, flow cytometry, immunohistochemistry, and western blotting) were performed to assess cell viability and apoptosis levels, as well as γH2A.X (DNA damage correlation), ribonucleotide reductase catalytic subunit M1 and M2 (RRM1 and RRM2, respectively) protein levels (iron-dependent correlation). 3-AP time- and dose-dependably suppressed growth and induced apoptosis in all three OS cell lines, and ferric ammonium citrate (FAC) blocked these effects. Moreover, 3-AP decreased RRM2 and total ribonucleotide reductase (RRM1 plus RRM2) protein expression but significantly increased γH2A.X expression; treatment did not affect RRM1 expression. Again, FAC treatment attenuated these effects. In vivo, the number of apoptotic cells in the tumor slices increased in the 3-AP-treated mice compared to the control mice. 3-AP treatment also decreased Ki-67 and p21 expression, suggesting inhibited OS growth. Furthermore, the expression of RRM1, RRM2, and transferrin receptor protein 1 (i.e., Tfr1) indicated that 3-AP inhibited OS growth via an iron-dependent pathway. In conclusion, 3-AP exhibits anticancer activity in OS by decreasing the activity of iron-dependent pathways, which could be a promising therapeutic strategy for OS.

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.

Psoralidin inhibits osteosarcoma growth and metastasis by downregulating ITGB1 expression via the FAK and PI3K/Akt signaling pathways

BACKGROUND

Psoralea corylifolia is a medicinal leguminous plant that has long been used to treat various diseases. Psoralidin (PSO) is the main extract compound of P. corylifolia and exhibits antibacterial, antitumor, anti-inflammatory, antioxidant, and other pharmacological activities. PSO has demonstrated inhibitory effects in several cancers; however, its inhibitory effect on osteosarcoma has not been reported. This study aimed to evaluate the inhibitory effect of PSO on osteosarcoma and elucidate the underlying molecular mechanisms.

METHODS

Crystal violet, cell counting kit-8 (CCK8), and 5-Ethynyl-2'-deoxyuridine (EdU) staining assays were used to assess the inhibitory effect of PSO on the proliferation of 143B and MG63 osteosarcoma cells. Wound healing and Transwell assays were conducted to evaluate the effects of PSO on osteosarcoma cell migration and invasion. The cell cycle and apoptosis were analyzed using flow cytometry. To determine the possible molecular mechanisms, RNA-sequencing was performed and protein expression was analyzed by western blotting. The inhibitory effect of PSO on osteosarcoma in vivo was analyzed using a mouse model of orthotopic osteosarcoma and immunohistochemistry.

RESULTS

PSO inhibited osteosarcoma cell proliferation in a concentration-dependent manner, inhibited cell migration and invasion, and induced cell-cycle arrest and apoptosis. Mechanistically, PSO treatment significantly inhibited the focal adhesion kinase (FAK) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways by downregulating ITGB1 expression in both MG63 and 143B cells. Furthermore, we demonstrated that PSO restrained osteosarcoma growth in vivo.

CONCLUSION

PSO may suppress osteosarcoma via the FAK and PI3K/Akt signaling pathways by downregulating ITGB1 expression.

Injectable rhein-assisted crosslinked hydrogel for efficient local osteosarcoma chemotherapy

Osteosarcoma (OS) is the most common malignant tumor of the bone that affects children and adolescents, and its treatment usually involves doxorubicin hydrochloride (DOX). However, the drug resistance and side effects caused by high-dose DOX infusion greatly hinder its therapeutic effects. To achieve efficient OS treatment with low toxicity, an injectable rhein (RH)-assisted crosslinked hydrogel (PVA@RH@DOX hydrogel, PRDH) was designed, which was prepared by loading DOX and RH into a polyvinyl alcohol (PVA) solution. The cytotoxicity assay and live/dead staining results showed that the combination of RH and DOX more effectively killed OS cells, producing excellent effects at low concentrations of DOX. The wound healing and transwell test results proved that PRDH could significantly inhibit the metastasis and invasion of OS cells. PRDH showed a long-lasting antitumor effect after injection of a single dose, significantly suppressing the proliferation and metastasis of OS and achieving the strategy of a single administration for long-term treatment. Excitingly, RH facilitated hydrogel formation by assisting with PVA crosslinking. This system provides an alternative regimen and broadens the horizon for the clinical treatment of OS.

Polypeptide N-Acetylgalactosaminyltransferase 14 (GALNT14) as a Chemosensitivity-Related Biomarker for Osteosarcoma

Purpose

Osteosarcoma is the most common primary bone tumor. Polypeptide N-acetylgalactosaminyltransferase 14 (GALNT14), a member of the N-acetylgalactosaminyltransferase family, has been considered to be associated with various cancers. However, its role in osteosarcoma remains unknown. Here, we aimed to explore the expression and potential mechanism of GALNT14 in osteosarcoma through bioinformatics analysis and in vitro experiments.

Methods

We investigated GALNT14 expression in osteosarcoma using GEO, the TIMER database, and clinical samples. Protein-protein interaction (PPI) network analysis on GALNT14 was performed by STRING. TARGET was used to identify differentially expressed genes (DEGs) between high and low GALNT14 expression. The correlation between GALNT14 and cuproptosis-related genes in osteosarcoma was analyzed by R language. The prognostic significance of GALNT14 was examined by Kaplan-Meier survival analysis. Additionally, we inhibited GALNT14 function in an osteosarcoma cell line by transfecting siRNA and subsequently explored the effect on drug sensitivity by CCK-8, clonogenic assay, and flow cytometry.

Results

GALNT14 was significantly elevated in osteosarcoma tissue, osteosarcoma cell lines, and metastatic osteosarcoma. PPI analysis revealed that GALNT14 was associated with MUC7, MUC13, MUC5AC, C1GALT1, MUC15, MUC16, MUC1, MUC4, MUC21, and MUC17. In the high GALNT14 expression group, we discovered 81 upregulated DEGs and 73 downregulated DEGs. Functional enrichment analysis of DEGs showed significant enrichment in the Wnt, TGF-β, Hippo, PI3K signaling pathways and cell adhesion molecules. Expression of cuproptosis-related genes was closely related in osteosarcoma, and GALNT14 expression was significantly positively correlated with FDX1, a key regulator of cuproptosis. Kaplan-Meier survival showed that GALNT14 was linked to poor overall survival and disease-free survival in osteosarcoma. In vitro experiments suggested that GALNT14 was associated with chemotherapy resistance in osteosarcoma.

Conclusion

We identified a GALNT family gene, GALNT14, that was highly expressed in osteosarcoma. This gene was closely associated with metastasis, progression, cuproptosis-related genes, and chemosensitivity of osteosarcoma, and showed correlation with poor overall survival and disease-free survival in osteosarcoma.

Heparin and Heparin-Based Drug Delivery Systems: Pleiotropic Molecular Effects at Multiple Drug Resistance of Osteosarcoma and Immune Cells

One of the main problems of modern health care is the growing number of oncological diseases both in the elderly and young population. Inadequately effective chemotherapy, which remains the main method of cancer control, is largely associated with the emergence of multidrug resistance in tumor cells. The search for new solutions to overcome the resistance of malignant cells to pharmacological agents is being actively pursued. Another serious problem is immunosuppression caused both by the tumor cells themselves and by antitumor drugs. Of great interest in this context is heparin, a biomolecule belonging to the class of glycosaminoglycans and possessing a broad spectrum of biological activity, including immunomodulatory and antitumor properties. In the context of the rapid development of the new field of “osteoimmunology,” which focuses on the collaboration of bone and immune cells, heparin and delivery systems based on it may be of intriguing importance for the oncotherapy of malignant bone tumors. Osteosarcoma is a rare but highly aggressive, chemoresistant malignant tumor that affects young adults and is characterized by constant recurrence and metastasis. This review describes the direct and immune-mediated regulatory effects of heparin and drug delivery systems based on it on the molecular mechanisms of (multiple) drug resistance in (onco) pathological conditions of bone tissue, especially osteosarcoma.

LncRNA FGD5-AS1 potentiates autophagy-associated doxorubicin resistance by regulating the miR-154-5p/WNT5A axis in osteosarcoma

Osteosarcoma is prevalent in children and adolescent. The oncogenic function of long-chain noncoding RNA (lncRNA) FGD5 antisense RNA 1 (FGD5-AS1) has been reported. However, the function of FGD5-AS1 in doxorubicin-resistance in osteosarcoma remains to be illucidated. Quantitative real-time PCR (qRT-PCR) and western blot analysis (WB) were used to measure the expression of FGD5-AS1, miR-154-5p, WNT5A and autophagy proteins. MTT assay was used to assess cell viability and transwell assay was performed to evaluate migration. A nude mouse xenograft model was developed to verify the function of FGD5-AS1 in vivo. FGD5-AS1 was upregulated in doxorubicin-resistant (DXR) osteosarcoma cells. Knockdown of FGD5-AS1 suppressed osteosarcoma cell proliferation, migration, and autophagy. FGD5-AS1 upregulated WNT5A expression via sponging miR-154-5p. Furthermore, FGD5-AS1 enhanced osteosarcoma cell chemotherapy resistance through upregulation of WNT5A by inhibiting miR-154-5p. Suppression of FGD5-AS1 significantly suppressed tumor growth in nude mice. FGD5-AS1 may promote chemoresistance through WNT5A-induced autophagy by sponging miR-154-5p in osteosarcoma cells.

Antitumor Effect of Sclerostin against Osteosarcoma

Simple Summary

Osteosarcoma is highly variable and heterogeneous, which is one of the reasons for its resistance to treatment. Because osteosarcoma is defined by abnormal bone formation, we hypothesize its suppression could lead to effective treatment for all types of osteosarcomas. Sclerostin is secreted by osteocytes and inhibits the canonical pathway by binding to LRP5/6, thereby suppressing bone formation. The resulting suppression of bone formation leads to bone loss and osteoporosis. Here, we investigated the antitumor effect of sclerostin against osteosarcoma and found that sclerostin suppressed the proliferative capacity and migratory ability of osteosarcoma cells.

Abstract

Various risk factors and causative genes of osteosarcoma have been reported in the literature; however, its etiology remains largely unknown. Bone formation is a shared phenomenon in all types of osteosarcomas, and sclerostin is an extracellular soluble factor secreted by osteocytes that prevents bone formation by inhibiting the Wnt signaling pathway. We aimed to investigate the antitumor effect of sclerostin against osteosarcoma. Osteosarcoma model mice were prepared by transplantation into the dorsal region of C3H/He and BALB/c-nu/nu mice using osteosarcoma cell lines LM8 (murine) and 143B (human), respectively. Cell proliferations were evaluated by using alamarBlue and scratch assays. The migratory ability of the cells was evaluated using a migration assay. Sclerostin was injected intraperitoneally for 7 days to examine the suppression of tumor size and extension of survival. The administration of sclerostin to osteosarcoma cells significantly inhibited the growth and migratory ability of osteosarcoma cells. Kaplan–Meier curves and survival data demonstrated that sclerostin significantly inhibited tumor growth and improved survival. Sclerostin suppressed the proliferative capacity and migratory ability of osteosarcoma cells. Osteosarcoma model mice inhibited tumor growth and prolonged survival periods by the administration of sclerostin. The effect of existing anticancer drugs such as doxorubicin should be investigated for future clinical applications.

Development of a Nomogram for Predicting the Efficacy of Preoperative Chemotherapy in Osteosarcoma

Background

Due to the obvious heterogeneity of osteosarcoma, many patients are not sensitive to neoadjuvant chemotherapy. In this study, the clinical characteristics and auxiliary examinations of patients with osteosarcoma were used to predict the effect of preoperative chemotherapy, so as to guide the clinical adjustment of the treatment plan to improve the prognosis of patients.

Methods

In this study, 90 patients with pathologically confirmed osteosarcoma were included, and they were randomly divided into training cohort (n=45) and validation cohort (n=45). A prediction model of preoperative chemotherapy efficacy for osteosarcoma was established by multivariate logistic regression analysis, and a nomogram was used as the visualization of the model. The ROC curve and C-index were used to evaluate the accuracy of the nomogram. Decision curve analysis (DCA) was used to evaluate the net benefit of the nomogram in predicting the efficacy of neoadjuvant chemotherapy under different threshold probabilities.

Results

In the study, the age, gender, location, tumor volume, metastasis at the first visit, MSTS staging, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) were used in the multivariate logistic regression analysis and the construction of the nomogram. The AUC and C-index of the training cohort were 0.793 (95% CI: 0.632, 0.954) and 0.881 (95% CI: 0.776, 0.986), respectively. The AUC and C-index in the validation cohort were 0.791 (95% CI: 0.644, 0.938) and 0.813 (95% CI: 0.679, 0.947), respectively, which were close to the training cohort. DCA showed that the model had good clinical application value.

Conclusion

Based on the clinical characteristics of patients and auxiliary examinations, the nomogram can be good used to predict the efficacy of preoperative chemotherapy for osteosarcoma.

3',4'-Dihydroxyflavonol Modulates the Cell Cycle in Cancer Cells: Implication as a Potential Combination Drug in Osteosarcoma

New agents are demanded to increase the therapeutic options for osteosarcoma (OS). Although OS is the most common bone cancer in children and adolescents, it is considered a rare disorder. Therefore, finding adjuvant drugs has potential to advance therapy for this disease. In this study, 3′,4′-dihydroxyflavonol (DiOHF) was investigated to assess the effects in OS cellular models in combination with doxorubicin (Dox). MG-63 and U2OS human OS cells were exposed to DiOHF and Dox and tested for cell viability and growth. To elucidate the inhibitory effects of DiOHF, additional studies were conducted to assess apoptosis and cell cycle distribution, gene expression quantification of cell cycle regulators, and cytokinesis-block cytome assay to determine nuclear division rate. DiOHF decreased OS cell growth and viability in a concentration-dependent manner. Its combination with Dox enabled Dox dose reduction in both cell lines, with synergistic interactions in U2OS cells. Although no significant apoptotic effects were detected at low concentrations, cytostatic effects were demonstrated in both cell lines. Incubation with DiOHF altered cell cycle dynamics and resulted in differential cyclin and cyclin-dependent kinase expression. Overall, this study presents an antiproliferative action of DiOHF in OS combination therapy via modulation of the cell cycle and nuclear division.

MiR-196a promoted cell migration, invasion and the epithelial-mesenchymal transition by targeting HOXA5 in osteosarcoma

INTRODUCTION

Osteosarcoma (OS), aggressive neoplasms of the bone, is the most common primary bone cancer in children. MiR-196a usually low expressed in several tumors and its functions in osteosarcoma still unclear.

MATERIALS AND METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to assess the expression of miR-196a and the HOXA5. Cell metastasis and epithelial-mesenchymal transition (EMT) abilities were assessed using Transwell and western blot. The dual luciferase reporter assay was carried out to verify whether miR-196a directly targeted the 3'-untranslated region (UTR) of HOXA5 mRNA.

RESULTS

MiR-196a was overexpressed and HOXA5 was low expressed in osteosarcoma versus the non-tumor tissues and normal cell lines. Upregulation of miR-196a or downregulation of HOXA5 was associated with worse outcome of osteosarcoma patients. MiR-196a enhanced cell migration, invasion and EMT by regulating the expression of HOXA5 through directly targeting the 3'-UTR of its mRNA in osteosarcoma. HOXA5 partially reversed roles of miR-196a on metastasis and EMT in osteosarcoma.

CONCLUSIONS

MiR-196a promoted cell metastasis and EMT by targeting the 3'-UTR of HOXA5 mRNA in osteosarcoma. The newly identified miR-196a/HOXA5 axis provides novel insight into the pathogenesis of osteosarcoma.

Mitochondria-targeting graphene oxide nanocomposites for fluorescence imaging-guided synergistic phototherapy of drug-resistant osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most common primary malignant bone tumor occurring in children and young adults. Drug-resistant osteosarcoma often results in chemotherapy failure. Therefore, new treatments aimed at novel therapeutic targets are urgently needed for the treatment of drug-resistant osteosarcoma. Mitochondria-targeted phototherapy, i.e., synergistic photodynamic/photothermal therapy, has emerged as a highly promising strategy for treating drug-resistant tumors. This study proposed a new nano-drug delivery system based on near-infrared imaging and multifunctional graphene, which can target mitochondria and show synergistic phototherapy, with preferential accumulation in tumors.

METHODS AND RESULTS

Based on our previous study, (4-carboxybutyl) triphenyl phosphonium bromide (TPP), a mitochondria-targeting ligand, was conjugated to indocyanine green (ICG)-loaded, polyethylenimine-modified PEGylated nanographene oxide sheets (TPP-PPG@ICG) to promote mitochondrial accumulation after cellular internalization. Thereafter, exposure to a single dose of near-infrared irradiation enabled synergistic photodynamic and photothermal therapy, which simultaneously inhibited adenosine triphosphate synthesis and mitochondrial function. Induction of intrinsic apoptosis assisted in surmounting drug resistance and caused tumor cell death. After fluorescence imaging-guided synergistic phototherapy, the mitochondria-targeting, multifunctional graphene-based, drug-delivery system showed highly selective anticancer efficiency in vitro and in vivo, resulting in marked inhibition of tumor progression without noticeable toxicity in mice bearing doxorubicin-resistant MG63 tumor cells.

CONCLUSION

The mitochondria-targeting TPP-PPG@ICG nanocomposite constitutes a new class of nanomedicine for fluorescence imaging-guided synergistic phototherapy and shows promise for treating drug-resistant osteosarcoma.

miR-26a Reverses Multidrug Resistance in Osteosarcoma by Targeting MCL1

The multidrug resistance (MDR) acquired in human osteosarcoma is a huge obstacle for effective chemotherapy. Recently, microRNA-26a (miR-26a) has been associated with the pathogenesis and progression of osteosarcoma. However, whether it regulates MDR in osteosarcoma is unknown. We show here that miR-26a expression declines in chemoresistant osteosarcoma after neoadjuvant chemotherapy, and its expression correlates with clinical outcome. In addition, compared with sensitive parental cells, miR-26a expression also declines in osteosarcoma MDR cells, together suggesting a negative correlation between miR-26a expression and MDR development in osteosarcoma. We also show that the enforced expression of miR-26a reverses MDR in osteosarcoma cells, and conversely, miR-26a knockdown confers MDR in chemosensitive osteosarcoma cells treated with doxorubicin, methotrexate, or cisplatin. Mechanistically, miR-26a directly targets the pro-survival protein myeloid cell leukemia 1 (MCL1), and in turn, the enforced expression of MCL1 markedly antagonizes miR-26a-decreased MDR in osteosarcoma MDR cells, therefore demonstrating that miR-26a reverses MDR in osteosarcoma by targeting MCL1. Lastly, miR-26a reverses resistance to doxorubicin in osteosarcoma MDR cells xenografted in nude mice. Collectively, these results reveal a negative role and the underlying mechanism of miR-26a in the regulation of MDR in human osteosarcoma, implying a potential tactic of manipulating miR-26a for overcoming MDR in osteosarcoma chemotherapy.

CircSAMD4A contributes to cell doxorubicin resistance in osteosarcoma by regulating the miR-218-5p/KLF8 axis

Circular RNA sterile alpha motif domain containing 4A (circSAMD4A) was found to be differentially expressed in osteosarcoma and contributed to the tumorigenesis of osteosarcoma. However, the role of circSAMD4A in doxorubicin (DXR) resistance of osteosarcoma is yet to be elucidated. Levels of circSAMD4A, microRNA (miR)-218-5p and Krüppel-like factor 8 (KLF8) were detected using quantitative reverse transcription-polymerase chain reaction. Western blot was applied to detect the protein levels of KLF8, cyclin D1 and p21. Cell viability, cell cycle, migration and invasion were analyzed using Cell Counting Kit-8 assay, flow cytometry and transwell assay, respectively. The interaction between miR-218-5p and circSAMD4A or KLF8 was verified using dual-luciferase reporter assay or RNA immunoprecipitation assay. In vivo experiments were performed using murine xenograft models. CircSAMD4A and KLF8 were elevated in osteosarcoma, and knockdown of circSAMD4A or KLF8 sensitized osteosarcoma cells to DXR by mediating resistant cell viability, migration and invasion inhibition, and cell cycle arrest in vitro. miR-218-5p was decreased in osteosarcoma, and miR-218-5p inhibition enhanced DXR resistance. Besides, miR-218-5p was found to bind to circSAMD4A or KLF8, and subsequent rescue experiments indicated that miR-218-5p inhibition reversed the inhibitory effects of circSAMD4A silencing on DXR resistance, and silencing miR-218-5p enhanced DXR resistance by targeting KLF8 in osteosarcoma cells. Moreover, circSAMD4A could indirectly regulate KLF8 via miR-218-5p. Additionally, circSAMD4A knockdown enhanced the cytotoxicity of DXR in osteosarcoma in vivo via regulating miR-218-5p and KLF8. In all, circSAMD4A enhanced cell DXR resistance in osteosarcoma by regulating the miR-218-5p/KLF8 axis, suggesting a novel therapeutic target for therapy-resistant osteosarcoma.

Identification of CDCA8, DSN1 and BIRC5 in Regulating Cell Cycle and Apoptosis in Osteosarcoma Using Bioinformatics and Cell Biology

Introduction:

Osteosarcoma is the most common primary tumor of bone, although some molecular markers have been identified, the detailed molecular mechanisms underlying osteosarcoma are currently not fully understood. In the present study, we attempted to identify the potential key genes and pathways in osteosarcoma using bioinformatics analysis.

Methods:

GSE14359 was downloaded from the GEO database, and analyzed using Limma package. Gene Ontology and pathway enrichment analyses of the DEGs were performed in the DAVID database, followed by the construction of a protein–protein interaction (PPI) network with software Cytoscape, subnetwork modules were subsequently identified and analyzed, and further validation in human osteosarcoma tissues and osteosarcoma cells line was performed.

Results:

964 Differentially expressed genes (DEGs) identified, of which 222 were up-regulated and 742 were down-regulated. Among them, 10 genes (including BIRC5, MAD2L1, Bub1, DSN1, SPC24, CDCA8, STAG2, CENPA, MLF1IP and Mis12) were identified as hub genes and they were mainly enriched in pathways, including mRNA surveillance, RNA transport and PI3K-Akt signaling pathways. Further validation indicated 6 gene (DSN1, BIRC5, CDCA8, MLF1IP, MAD2L1 and SPC24) is highly expressed in osteosarcoma tissues. Among them, CDCA8, DSN1 and BIRC5 significantly promoted the proliferation of osteosarcoma cells in vitro. In terms of mechanism, DSN1 and CDCA8 were mainly involved in cell cycle regulation, while BIRC5 was mainly involved in the regulation of apoptosis pathway.

Conclusions:

We identified some key genes and pathways in osteosarcoma, which might be used as molecular targets or diagnostic biomarker for the diagnosis and therapy of osteosarcoma.

The enhancement apoptosis of osteosarcoma mesenchymal stem cells co-cultivation with peripheral blood mononuclear cells sensitized by secretome and granulocyte macrophage colony-stimulating factor

The advanced, metastasis, and reccurent of osteosarcoma (OS) patients have a poor prognosis postaggresive surgery and chemotherapy. Peripheral blood mononuclear cells (PBMCs) as cell-based immunotherapy may successful in the OS treatment. To investigate the enhancement apoptosis of OS-mesenchymal stem cells (OS-MSCs) co-cultivated with PBMCs sensitized using the secretome and granulocyte macrophage colony-stimulating factor (GMCSF). This true experimental study with posttest only control group design and in vitro study. The sample was cultured OS-MSCs which confirmed by Cluster of Differentiation-133 using immunocytochemistry (ICC) and histopathology analysis. The sample divided into six groups accordingly: OS-MSC, OS-MSC + PMBC, OS-MSC + PMBC + Secretome, OS-MSC + PMBC + GMCSF, OS-MSC + PBMC + Secretome + GMCSF (n = 5/N = 30). The enhancement of OS-MSCs apoptosis was analyzed through Interleukin-2 (IL-2) level through the Enyzme-Linked Immunosorbent Assay examination, expression of Signal Transducers and Activators of Transcription (STAT)-3 and caspase-3 by ICC. One-way analysis of variance test and Tukey Honestly Significant Difference to analyze the difference between the groups (P < 0.05). The highest of IL-2 level was found in the PBMC + Secretome + GMCSF group. The highest expression of caspase-3 was found in OS-MSC + PBMC + Secretome + GMCSF group with significant different between groups (P < 0.05). There was insignificant difference of STAT-3 epxression and IL-2 level between groups (P > 0.05). The co-cultivation of OS-MSCs and PBMSCs activated using secretome and GMCSF has a great ability to enhance OS-MSCs apoptosis.

Alantolactone inhibits proliferation, metastasis and promotes apoptosis of human osteosarcoma cells by suppressing Wnt/β-catenin and MAPKs signaling pathways

Although there are many therapeutic strategies such as surgery and chemotherapy, the prognosis of osteosarcoma (OS) is still far from being satisfactory. It is urgent to develop more effective, tolerable and safe drugs for the treatment of OS. In the present study, we investigated the anti-OS activity of Alantolactone (ALT), a natural eucalyptone sesquiterpene lactone mainly exists in Inula helenium, and probed the possible mechanism involved. We demonstrated that ALT significantly inhibited cell proliferation of various human OS cell lines while had relative lower cytotoxicity against normal cells. Then, we validated that ALT reduced migration, decreased invasion possibly through reversing epithelial mesenchymal transition (EMT) process and suppressing Matrix metalloproteinases (MMPs). Moreover, we confirmed that ALT promoted apoptosis and arrested cell cycle at G2/M phase of human OS cells in vitro. In addition, we confirmed that ALT restrained tumor growth and metastasis of OS 143 cells in a xenograft model in vivo. Mechanistically, ALT inhibited the activity of Wnt/β-catenin and p38, ERK1/2 and JNK Mitogen Activated Protein Kinases (MAPKs) signal pathway. Notably, the combination of ALT and Wnt/β-catenin inhibitor, as well as the combination of ALT and MAPKs inhibitors resulted in a synergistically effect on inhibiting the proliferation, migration and invasion of OS cells. Collectively, our results validate the ALT may inhibit proliferation, metastasis and promotes apoptosis of human OS cells possibly through suppressing Wnt/β-Catenin and MAPKs signaling pathways.

Analysis of Transcriptomic Similarity between Osteosarcoma Cell Lines and Primary Tumors

BACKGROUND

Osteosarcoma (OS) cell lines are commonly used to mimic tumors for in vitro experiments. The present study explores the resemblance of OS cell lines to OS primary tumors in regard to gene expression.

METHODS

Transcriptomic data were retrieved from published data sets for 18 primary tumor samples and 13 commonly used OS cell lines. Tumor purity was accounted for when correlating tumor and cell line gene expression. Differentially expressed genes between tumors and cell lines were discovered and gene ontology analysis was performed.

RESULTS

Certain commonly used cell lines, including NY, NOS1, and U2OS, display less resemblance to OS tumors than do other cell lines. For genes overexpressed in tumors, and consequently underexpressed in cell lines, gene ontology analysis enriched pathways related to cell-cell adhesion and stimulus detection.

CONCLUSION

The pathways dysregulated between cell lines and tumors have been implicated in OS pathogenesis. Therefore, the findings suggest that the transcriptome of OS cell lines may not be completely representative of OS primary tumors' gene expression and the disease process.

Loss of histone H4 lysine 20 trimethylation in osteosarcoma is associated with aberrant expression ofhistone methyltransferase SUV420H2

Epigenetic modifications of histones have crucial roles in various types of cancers. The aberrant trimethylation of histone H4 at lysine 20 (H4K20) has been implicated in carcinogenesis. At present, the status of trimethylation at H4k20 (H4K20me3) in osteosarcoma (OS), the predominant bone cancer in humans, is unknown. In the present study, a genome-wide decrease was observed in H4K20me3 levels in OS tissues and cell lines. Reduced levels of lysine methyltransferase 5C (SUV420H2), the histone methyltranferase responsible for modification of H4K20me3, was also observed in OS cells with the associated loss of H4K20me3. Furthermore, a total of 507 SUV420H2-regulated genes were identified through RNA-seq and a number of candidate genes were further validated. Bioinformatic analysis revealed an association between SUV420H2 and multiple signaling pathway, including the mitogen-activated protein kinase, P53, transforming growth factor and the ErbB pathways. These results demonstrated that there are aberrant levels of H4K20me3 and SUV420H2 in OS, and highlighted H4K20me3 as a candidate biomarker for the early detection of OS.

Ginsenoside Rg3 Inhibits the Growth of Osteosarcoma and Attenuates Metastasis through the Wnt/β-Catenin and EMT Signaling Pathway

Osteosarcoma (OS) is the most common primary malignant bone cancer. An increasing number of studies have demonstrated that ginsenoside Rg3 (Rg3), which is extracted from the roots of the traditional Chinese herb Panax ginseng, plays a tumor suppression role in various malignant tumors. In the present study, we aimed at investigating the role of Rg3 in the proliferation, migration, and invasion of OS and at exploring the underlying mechanisms. Cell viability and proliferation were observed by MTT assay and crystal violet staining. The migration and invasion of cells were measured by wound-healing assay and Transwell method. Signaling pathway screening was investigated using luciferase reporter gene assay. qRT-PCR and western blot were performed to measure the expression of molecules involved in cell epithelial-mesenchymal transition (EMT), and Wnt/β-catenin pathway. Results suggested that Rg3 could not only inhibit proliferation but also hamper the migration and invasion of OS. qRT-PCR and western blot demonstrated that a reduced level of MMP2/MMP7/MMP9 was induced after Rg3 treatment. In addition, the expression levels of proteins related to EMT and the Wnt/β-catenin pathway were downregulated. In summary, our data revealed that Rg3 could inhibit the proliferation, migration, and invasion of OS cells. This effect of Rg3 might be mediated by downregulating MMP2, MMP7, and MMP9 expression and suppressing EMT as well as the Wnt/β-catenin pathway. Thus, Rg3 might be a potential agent for the treatment of OS.

FBXO2 modulates STAT3 signaling to regulate proliferation and tumorigenicity of osteosarcoma cells

Background

Osteosarcoma (OS) is the most common primary bone malignancy in children and adolescents, and hyperproliferation of cells is a major problem of OS. FBXO2 belongs to the family of F-box proteins, and is a substrate recognition component of the Skp1-Cul1-F-box protein (SCF) E3 ubiquitin ligase complex with specificity for high-mannose glycoproteins. The aim of the present study was to investigate the critical role of FBXO2 in OS cells.

Methods

The protein and mRNA expression levels of FBXO2 in clinic OS patients were measured by quantitative real time-polymerase chain reaction (qRT-PCR), Western blot and Immunohistochemical (IHC) staining assays, respectively. The FBXO2 overexpression model was constructed by retro-virus transfection in OS cells. FBXO2 knockout (KO) cells were generated by Clustered regularly interspaced short palindromic repeat (CRISPR)-CRISPR-associated protein 9 (Cas9) assay. Cell counting and colony formation assays were used to analyze the effect of FBXO2 on the biological function of OS cells. FBXO2 KO cells were injected into nude mice to observe tumor growth in vivo. The interaction between FBXO2 and IL-6 was detected by immunoprecipitation. Luciferase assay was used to determine the transcriptional activity of STAT3.

Results

Here, we show that FBXO2 is significantly up-regulated in clinical OS samples compared to adjacent normal tissues. Ectopic expression of FBXO2 leads to increased OS cell proliferation and colony-forming ability, while FBXO2 knockout by CRISPR-Cas9-based gene editing has the opposite effect. In addition, the glycoprotein recognition activity of FBXO2 is required for its biological function in OS. In vivo experiments showed that FBXO2 knockout greatly impaired the tumorigenicity of OS cells in nude mice. At the molecular level, we found that knocking out FBXO2 can significantly inhibit STAT3 phosphorylation and downstream target gene expression through IL-6R stabilization.

Conclusion

Together, these results indicate that FBXO2 promotes OS development by activating the STAT3 signaling pathway, suggesting that FBXO2 may be a new target for OS treatment.

Sea cucumber Cucumaria frondosa fucoidan inhibits osteosarcoma adhesion and migration by regulating cytoskeleton remodeling

Osteosarcoma (OS) has been demonstrated to be difficult to cure due to its potently malignant metastasis. Therefore, new therapeutic approaches blocking the metastatic potential of OS are urgently required to improve the outcomes for OS patients. In the present study, the anti-metastatic capacity of sea cucumber (Cucumaria frondosa) fucoidan (Cf-Fuc) was evaluated on osteosarcoma cells by cell adhesion assay, Transwell assay and U2OS cell migration assay. The underlying mechanism on the dynamic remodeling of the cytoskeleton was also explored. The present data indicated that Cf-Fuc could block the U2OS osteosarcoma cell adhesion to fibronectin and significantly inhibit U2OS cell migration. Cf-Fuc greatly impaired the migration capacity of U2OS cells, and the migrated distance and velocity of Cf-Fuc-treated cells were markedly reduced. Also, Cf-Fuc could impair the dynamic remodeling of the cytoskeleton possibly by suppressing the phosphorylation of focal adhesion kinase and paxillin, as well as the activation of the Rac1/PAK1/LIMK1/cofilin signaling axis. Collectively, the present findings provide a novel therapeutic potential of C. frondosa fucoidan for osteosarcoma metastasis.

ABCA1/ABCB1 Ratio Determines Chemo- and Immune-Sensitivity in Human Osteosarcoma

The ATP Binding Cassette transporter B1 (ABCB1) induces chemoresistance in osteosarcoma, because it effluxes doxorubicin, reducing the intracellular accumulation, toxicity, and immunogenic cell death induced by the drug. The ATP Binding Cassette transporter A1 (ABCA1) effluxes isopentenyl pyrophosphate (IPP), a strong activator of anti-tumor Vγ9Vδ2 T-cells. Recruiting this population may represent an alternative strategy to rescue doxorubicin efficacy in ABCB1-expressing osteosarcoma. In this work, we analyzed how ABCA1 and ABCB1 are regulated in osteosarcoma, and if increasing the ABCA1-dependent activation of Vγ9Vδ2 T-cells could be an effective strategy against ABCB1-expressing osteosarcoma. We used 2D-cultured doxorubicin-sensitive human U-2OS and Saos-2 cells, their doxorubicin-resistant sublines (U-2OS/DX580 and Saos-2/DX580), and 3D cultures of U-2OS and Saos-2 cells. DX580-sublines and 3D cultures had higher levels of ABCB1 and higher resistance to doxorubicin than parental cells. Surprisingly, they had reduced ABCA1 levels, IPP efflux, and Vγ9Vδ2 T-cell-induced killing. In these chemo-immune-resistant cells, the Ras/Akt/mTOR axis inhibits the ABCA1-transcription induced by Liver X Receptor α (LXRα); Ras/ERK1/2/HIF-1α axis up-regulates ABCB1. Targeting the farnesylation of Ras with self-assembling nanoparticles encapsulating zoledronic acid (NZ) simultaneously inhibited both axes. In humanized mice, NZ reduced the growth of chemo-immune-resistant osteosarcomas, increased intratumor necro-apoptosis, and ABCA1/ABCB1 ratio and Vγ9Vδ2 T-cell infiltration. We suggest that the ABCB1^highABCA1^low phenotype is indicative of chemo-immune-resistance. We propose aminobisphosphonates as new chemo-immune-sensitizing tools against drug-resistant osteosarcomas.

Interleukin-22 modulates cisplatin sensitivity of osteosarcoma cells by regulating the STAT3 signaling pathway

The present study aimed to investigate the regulatory mechanisms by which interleukin (IL)-22 regulates cisplatin (DDP) sensitivity in osteosarcoma cells. Firstly, reverse transcription-quantitative (RT-q) PCR and western blotting demonstrated that IL-22 expression was significantly increased in osteosarcoma tissues and cell lines compared with the adjacent normal tissues and the normal osteoblast hFOB1.19 cells. Subsequently, the MG63 osteosarcoma cell line and cisplatin-resistant MG63/DDP osteosarcoma cell line were treated with different concentrations of cisplatin (2.5, 5.0, 10, 20, 40 and 80 µg/ml), and the half maximal inhibitory concentration (IC₅₀) was calculated based on the MTT assay. The results showed that the IC₅₀ of DDP in MG63/DDP cells was significantly higher than that in MG63 cells. Furthermore, IL-22 expression was higher in MG63/DDP cells compared with MG63 cells. Subsequently, the effects of IL-22 downregulation and overexpression on MG63/DDP and MG63 cells were assessed using the MTT assay, flow cytometry, RT-qPCR and western blotting. The IL-22 small interfering (si) RNA in MG63/DDP cells significantly decreased the IC₅₀ of DDP and decreased the cell viability of MG63/DDP cells. Furthermore, IL-22 RNA interference decreased BCl-2 expression and phosphorylation of STAT3, induced apoptosis, and increased the expression of Bax and cleaved caspase-3. The IL-22 overexpression plasmid had opposite effects to the observations in IL-22 siRNA-transfected MG63 cells. Overall, the present study indicated that IL-22 regulated the cell viability and apoptosis of osteosarcoma cells by regulating the activation of the STAT3 signaling pathway and affecting the expression of apoptosis-associated genes, and thereby mediating the sensitivity of osteosarcoma cells to cisplatin.

SIAH1/ZEB1/IL-6 axis is involved in doxorubicin (Dox) resistance of osteosarcoma cells

Osteosarcoma (OS) patients often exhibit pulmonary metastasis, which results in high patient mortality. Our present study established the doxorubicin (Dox) resistant human OS MG-63 and HOS cells and named them MG-63/Dox and HOS/Dox, respectively. The Dox resistant OS cells had greater invasion ability than that of parental cells. The expression of ZEB1, while not FOXM1, Snail, HIF-1α, or Sp1, was significantly increased in Dox resistant OS cells. Silencing of ZEB1 can attenuate the metastasis and increase Dox sensitivity of MG-63/Dox and HOS/Dox cells. The upregulation of ZEB1 can increase of the expression of interlukin-6 (IL-6). Anti-IL-6 inhibited the invasion and increase the Dox sensitivity of MG-63/Dox and HOS/Dox cells. There was no significant difference of ZEB1 mRNA between Dox resistant and control cells. The upregulation of ZEB1 in Dox resistant OS cells can be attributed to the increase of protein half-life. This was confirmed by results that the inhibitor of proteasomal degradation can increase ZEB1 in Dox resistant OS cells. Over expression of SIAH1 can inhibit the expression of ZEB1 and increase the Dox sensitivity of MG-63/Dox and HOS/Dox cells. Collectively, we confirmed that SIAH1 induced ZEB1 is involved in the Dox resistance of OS cells.

Bone sarcoma patient-derived xenografts are faithful and stable preclinical models for molecular and therapeutic investigations

Standard therapy of osteosarcoma (OS) and Ewing sarcoma (EW) rests on cytotoxic regimes, which are largely unsuccessful in advanced patients. Preclinical models are needed to break this impasse. A panel of patient-derived xenografts (PDX) was established by implantation of fresh, surgically resected osteosarcoma (OS) and Ewing sarcoma (EW) in NSG mice. Engraftment was obtained in 22 of 61 OS (36%) and 7 of 29 EW (24%). The success rate in establishing primary cell cultures from OS was lower than the percentage of PDX engraftment in mice, whereas the reverse was observed for EW; the implementation of both in vivo and in vitro seeding increased the proportion of patients yielding at least one workable model. The establishment of in vitro cultures from PDX was highly efficient in both tumor types, reaching 100% for EW. Morphological and immunohistochemical (SATB2, P-glycoprotein 1, CD99, caveolin 1) studies and gene expression profiling showed a remarkable similarity between patient’s tumor and PDX, which was maintained over several passages in mice, whereas cell cultures displayed a lower correlation with human samples. Genes differentially expressed between OS original tumor and PDX mostly belonged to leuykocyte-specific pathways, as human infiltrate is gradually replaced by murine leukocytes during growth in mice. In EW, which contained scant infiltrates, no gene was differentially expressed between the original tumor and the PDX. A novel therapeutic combination of anti-CD99 diabody C7 and irinotecan was tested against two EW PDX; both drugs inhibited PDX growth, the addition of anti-CD99 was beneficial when chemotherapy alone was less effective. The panel of OS and EW PDX faithfully mirrored morphologic and genetic features of bone sarcomas, representing reliable models to test therapeutic approaches.

An update on emerging drugs in osteosarcoma: towards tailored therapies?

Introduction: Current treatment of conventional and non-conventional high-grade osteosarcoma (HGOS) is based on the surgical removal of primary tumor and, when possible, of metastases and local reccurrence, together with systemic pre- and post-operative chemotherapy with drugs that have been used since decades. Areas covered: This review is intended to summarize the new agents and therapeutic strategies that are under clinical evaluation in HGOS, with the aim to increase the cure probability of this highly malignant bone tumor, which has not significantly improved during the last 30-40 years. The list of drugs, compounds and treatment modalities presented and discussed here has been generated by considering only those that are included in presently ongoing and recruiting clinical trials, or which have been completed in the last 2 years with reported results, on the basis of the information obtained from different and continuously updated databases. Expert opinion: Despite HGOS is a rare tumor, several clinical trials are presently evaluating different treatment strategies, which may hopefully positively impact on the outcome of patients who experience unfavorable prognosis when treated with conventional therapies.

Dihydrotanshinone I inhibits the growth of osteosarcoma through the Wnt/β-catenin signaling pathway

Background: Osteosarcoma is a common malignant tumor, with relatively lower survival rates in adolescents. Dihydrotanshinone I (DHI) was extracted from the traditional Chinese medicine Salvia miltiorrhiza and was shown to inhibit several types of cancer. Purpose: To explore the effect of DHI on the proliferation, migration, invasion, and apoptosis of osteosarcoma cells, as well as the possible molecular mechanism. Methods: The effect of DHI on the proliferation of osteosarcoma was detected by crystal violet assay, MTT assay, colony formation assay. The effects of DHI on the migration and invasion of osteosarcoma were detected by wound healing assays, cell migration and invasion assays. The effect of DHI on apoptosis of osteosarcoma was detected by cell apoptosis assay and Hoechst apoptosis staining. The protein expression levels were detected by Western blotting assay. The activity of Wnt/β-Catenin signaling pathway was detected by luciferase reporter assay and Western blot. The inhibitory effect of DHI on osteosarcoma in vivo was analyzed by an orthotopic OS tumor animal model and immunohistochemistry. Result: DHI may inhibit the proliferation, decrease the migration, reduce the invasion, and promote the apoptosis of osteosarcoma cells. In vivo mouse model, DHI can inhibit the formation of osteosarcoma. In terms of mechanism, DHI may inhibit both the transcriptional activity and the total protein level of β-catenin. Conclusion: DHI may inhibit the proliferation, migration, and invasion as well as induce the apoptosis of osteosarcoma cells, possibly through suppressing the Wnt/β-catenin signaling pathway.

Extracellular Nanovesicles Secreted by Human Osteosarcoma Cells Promote Angiogenesis

Angiogenesis involves a number of different players among which extracellular nanovesicles (EVs) have recently been proposed as an efficient cargo of pro-angiogenic mediators. Angiogenesis plays a key role in osteosarcoma (OS) development and progression. Acidity is a hallmark of malignancy in a variety of cancers, including sarcomas, as a result of an increased energetic metabolism. The aim of this study was to investigate the role of EVs derived from osteosarcoma cells on angiogenesis and whether extracellular acidity, generated by tumor metabolism, could influence EVs activity. For this purpose, we purified and characterized EVs from OS cells maintained at either acidic or neutral pH. The ability of EVs to induce angiogenesis was assessed in vitro by endothelial cell tube formation and in vivo using chicken chorioallantoic membrane. Our findings demonstrated that EVs derived from osteosarcoma cells maintained either in acidic or neutral conditions induced angiogenesis. The results showed that miRNA and protein content of EVs cargo are correlated with pro-angiogenic activity and this activity is increased by the acidity of tumor microenvironment. This study provides evidence that EVs released by human osteosarcoma cells act as carriers of active angiogenic stimuli that are able to promote endothelial cell functions relevant to angiogenesis.

Hyaluronated liposomes containing H2S-releasing doxorubicin are effective against P-glycoprotein-positive/doxorubicin-resistant osteosarcoma cells and xenografts

Doxorubicin (dox) is one of the first-line drug in osteosarcoma treatment but its effectiveness is limited by the efflux pump P-glycoprotein (Pgp) and by the onset of cardiotoxicity. We previously demonstrated that synthetic doxs conjugated with a H₂S-releasing moiety (Sdox) were less cardiotoxic and more effective than dox against Pgp-overexpressing osteosarcoma cells. In order to increase the active delivery to tumor cells, we produced hyaluronic acid (HA)-conjugated liposomes containing Sdox (HA-Lsdox), exploiting the abundance of the HA receptor CD44 in osteosarcoma. HA-Lsdox showed favorable drug-release profile and higher toxicity in vitro and in vivo than dox or the FDA-approved liposomal dox Caelyx^® against Pgp-overexpressing osteosarcoma, displaying the same cardiotoxicity profile of Caelyx^®. Differently from dox, HA-Lsdox delivered the drug within the endoplasmic reticulum (ER), inducing protein sulfhydration and ubiquitination, and activating a ER stress pro-apoptotic response mediated by CHOP. HA-Lsdox also sulfhydrated the nascent Pgp in the ER, reducing its activity. We propose HA-Lsdox as an innovative tool noteworthy to be tested in Pgp-overexpressing patients, who are frequently less responsive to standard treatments in which dox is one of the most important drugs.

Visfatin is involved in the cisplatin resistance of osteosarcoma cells via upregulation of Snail and Zeb1

Understanding the mechanisms of chemoresistance in osteosarcoma (OS) cell is important for drug development. By establishment of cisplatin (CDDP) resistant OS cells, we found that the levels of visfatin in OS/CDDP cells were significantly greater than that in their parental cells. The CDDP resistant OS cells showed greater migration and invasion capability than that of parental cells. Knockdown of visfatin can rescue the CDDP sensitivity of resistant OS cells. Among the detected epithelial-mesenchymal transition-related transcription factors (EMT-TFs), visfatin can increase the expression of Snail and Zeb-1 in OS cells. Overexpression of Snail and Zeb1 can attenuate si-visfatin reduced CDDP resistance of OS cells. Mechanistical studies indicated that visfatin can increase the mRNA expression of Snail and therefore upregulate its expression via HIF-1α induced transcription. As to Zeb1, visfatin had no effect on its mRNA expression, while significantly increased its protein stability. Furthermore, the upregulation of ATM, which can phosphorylate and stabilize Zeb1, was involved in visfatin-induced Zeb1 expression in OS cells. Collectively, our revealed that visfatin was involved in CDDP resistance of OS cells via upregulation of Snail and Zeb1, suggesting that inhibition of visfatin might be a potential pathway for OS treatment.

Current understanding of pharmacogenetic implications of DNA damaging drugs used in osteosarcoma treatment

INTRODUCTION

DNA damaging drugs are widely used for the chemotherapeutic treatment of high-grade osteosarcoma (HGOS). In HGOS patients, several germline polymorphisms have been reported to impact on the development of adverse toxic events related to DNA damaging drugs treatment. Some of these polymorphisms, when present in tumor cells, may also influence treatment response and prognosis of HGOS patients. Area covered: In this review, the authors have focused on pharmacogenetic markers (mainly germline polymorphisms) described in patients with HGOS, which have proved or indicated to be related to the susceptibility to adverse toxic reactions and/or to influence response to DNA damaging drugs. The concordant and discordant results reported in different studies have also been discussed. Expert opinion: Response and toxicity predisposition to DNA damaging drugs are influenced by genes encoding proteins involved in their uptake, efflux, activation, inactivation, and in DNA repair, activity of which may vary according to specific gene variations. In HGOS, there is a substantial medical need for biomarkers predictive for individual response and toxicity predisposition to DNA-targeting drugs, which may be used to tailor therapy in order to decrease the occurrence of adverse side effects and increase treatment efficacy and safety.

Tankyrase1 antisense oligodeoxynucleotides suppress the proliferation, migration and invasion through Hippo/YAP pathway in human osteosarcoma cells

Osteosarcoma is the most common malignant tumor of bone with a high potential for metastasis and poor prognosis. This study intends to explore the effect of tankyrase1 (TANK1) in the development of osteosarcoma cells and the underlying mechanism. The osteosarcoma cell line MG-63 cells were cultured and transfected with tankyrase1 antisense oligodeoxynucleotides (TANK1-ASODN). Cell proliferation was detected with CCK-8 and immunofluorescence. Cell migration and invasion were examined by wound healing assay and Transwell assay, respectively. Reverse transcription-quantitative polymerase chain reaction was performed to detect the mRNA level of TANK1 and western blot was conducted to detect relative protein expression during the research. As a result, we demonstrated that TANK1 was upregulated in osteosarcoma. The TANK1-ASODN inhibited MG-63 cell proliferation, migration and invasion. The progress of epithelial-mesenchymal transition (EMT) was also suppressed in TANK1-ASODN transfected MG-63 cells compared to control group. Besides, the TANK1-ASODN activated and modulated the Hippo/YAP signaling which might be the pathway that TANK1 depended on. Overall, our finding supported that TANK1-ASODN slowed down the progress of osteosarcoma by suppressing cell proliferation, migration, invasion and EMT through Hippo/YAP pathway.

Breaking the Depth Dependence by Nanotechnology-Enhanced X-Ray-Excited Deep Cancer Theranostics

The advancements in nanotechnology have created multifunctional nanomaterials aimed at enhancing diagnostic accuracy and treatment efficacy for cancer. However, the ability to target deep-seated tumors remains one of the most critical challenges for certain nanomedicine applications. To this end, X-ray-excited theranostic techniques provide a means of overcoming the limits of light penetration and tissue attenuation. Herein, a comprehensive overview of the recent advances in nanotechnology-enhanced X-ray-excited imaging and therapeutic methodologies is presented, with an emphasis on the design of multifunctional nanomaterials for contrast-enhanced computed tomography (CT) imaging, X-ray-excited optical luminescence (XEOL) imaging, and X-ray-excited multimodal synchronous/synergistic therapy. The latter is based on the concurrent use of radiotherapy with chemotherapy, gas therapy, photodynamic therapy, or immunotherapy. Moreover, the featured biomedical applications of X-ray-excited deep theranostics are discussed to highlight the advantages of X-ray in high-sensitivity detection and efficient elimination of malignant tumors. Finally, key issues and technical challenges associated with this deep theranostic technology are identified, with the intention of advancing its translation into the clinic.

Endoplasmic reticulum-targeting doxorubicin: a new tool effective against doxorubicin-resistant osteosarcoma

Doxorubicin is one of the most effective drugs for the first-line treatment of high-grade osteosarcoma. Several studies have demonstrated that the major cause for doxorubicin resistance in osteosarcoma is the increased expression of the drug efflux transporter ABCB1/P-glycoprotein (Pgp). We recently identified a library of H2S-releasing doxorubicins (Sdox) that were more effective than doxorubicin against resistant osteosarcoma cells. Here we investigated the molecular mechanisms of the higher efficacy of Sdox in human osteosarcoma cells with increasing resistance to doxorubicin. Differently from doxorubicin, Sdox preferentially accumulated within the endoplasmic reticulum (ER), and its accumulation was only modestly reduced in Pgp-expressing osteosarcoma cells. The increase in doxorubicin resistance was paralleled by the progressive down-regulation of genes of ER-associated protein degradation/ER-quality control (ERAD/ERQC), two processes that remove misfolded proteins and protect cell from ER stress-triggered apoptosis. Sdox, that sulfhydrated ER-associated proteins and promoted their subsequent ubiquitination, up-regulated ERAD/ERQC genes. This up-regulation, however, was insufficient to protect cells, since Sdox activated ER stress-dependent apoptotic pathways, e.g., the C/EBP-β LIP/CHOP/PUMA/caspases 12-7-3 axis. Sdox also promoted the sulfhydration of Pgp that was subsequently ubiquitinated: this process further enhanced Sdox retention and toxicity in resistant cells. Our work suggests that Sdox overcomes doxorubicin resistance in osteosarcoma cells by at least two mechanisms: it induces the degradation of Pgp following its sulfhydration and produces a huge misfolding of ER-associated proteins, triggering ER-dependent apoptosis. Sdox may represent the prototype of innovative anthracyclines, effective against doxorubicin-resistant/Pgp-expressing osteosarcoma cells by perturbing the ER functions.

In vitro and in vivo anticancer effects of two quinoline-platinum(II) complexes on human osteosarcoma models

Platinum-based drugs, mainly cisplatin, are used for the treatment of several solid tumors such as OS. However, cisplatin treatment often results in the development of chemoresistance, leading therapeutic failure. We have previously reported that platinum complexes containing 8-hydroxyquinoline ligands have good antitumor activity against different cancer cell lines and with a different and better cytotoxic profile than cisplatin. Here, the anticancer properties of two different quinoline-platinum complexes [Pt(Cl)₂(quinoline)(dmso)] (1) [PtCl(8-O-quinoline)(dmso)] (2) on in vitro (2D and 3D) and in vivo models (xenograft tumor of human osteosarcoma in mice) are presented. In this order, [PtCl(8-O-quinoline)(dmso)] (2) impaired cell viability to have a more pronounced antitumor effect than cisplatin on MG-63 osteosarcoma cells (IC₅₀ 4 µM vs. 39 µM). Besides, [PtCl(8-O-quinoline)(dmso)] (2) increased ROS production in a dose-manner response and this compound induced early and late apoptotic fractions of human osteosarcoma cells. Finally, [PtCl(8-O-quinoline)(dmso)] (2) decreased the cell viability of multicellular spheroids and reduced the tumor volume on athymic nude mice N:NIH(S) Fox1^nu without inducing side effects. In this way, [PtCl(8-O-quinoline)(dmso)] (2) did not alter the normal cytoarchitecture of liver and kidney and the blood biomarkers (GPT, GOT, uremia, and creatinine) did not suffer modifications. Taken together, our data indicate that these compounds showed a better anticancer performance than cisplatin on in vitro and in vivo studies. These results showed the importance of chelation in the antitumor properties, suggesting that the [PtCl(8-O-quinoline)(dmso)] (2) might be a promising agent for the treatment of human osteosarcoma tumors resistant to cisplatin.

Clinical epidemiology and treatment outcomes of spindle cell non-osteogenic bone sarcomas - A nationwide population-based study

Purpose

To describe epidemiological and clinical characteristics, as well as long-term treatment outcomes of spindle cell non-osteogenic bone sarcomas (SCS), comprising leiomyosarcoma, fibrosarcoma and undifferentiated pleomorphic sarcoma in bone.

Method

We have analysed a nationwide cohort of 104 patients with histologically verified SCS diagnosed between 1975 and 2009, based on registry sources supplemented with clinical records from Norwegian hospitals involved in sarcoma management.

Results

In this unselected cohort, a stable annual incidence for SCS patients of slightly below 0.6 per million was observed, with a dominant peak among elderly patients. SCS is mostly a high-grade malignancy (92%) with a male to female ratio of 1.6 for all patients. The axial to appendicular ratio was 0.7, seemingly independent of age. More than one fourth of the patients (29%) had primary metastatic disease. Another 32 patients (46%) developed metastases during follow-up and 12 (17%) experienced local relapses. The five-year sarcoma-specific survival rate was 37%, with no documented improvement over time. Primary metastatic disease was an adverse prognostic factor for survival. Predisposing factors were documented in 19 patients (18%). Negative prognostic factors for overall survival were tumour size >9 cm, age > 40 years, axial tumour localization, FS as subtype and pathologic fracture at time of diagnoses. As expected, patients who received both surgery and chemotherapy as their primary treatment for high-grade SCS (25%) significantly had best sarcoma specific five years survival (62%).

Conclusion

We confirm SCS as a rare high-grade bone sarcoma entity, mostly among elderly patients and with a poor overall outcome. The combined treatment of surgery and chemotherapy is essential to achieve optimal long-term survival of SCS.

Functionalized Keratin as Nanotechnology-Based Drug Delivery System for the Pharmacological Treatment of Osteosarcoma

Osteosarcoma therapy might be moving toward nanotechnology-based drug delivery systems to reduce the cytotoxicity of antineoplastic drugs and improve their pharmacokinetics. In this paper, we present, for the first time, an extensive chemical and in vitro characterization of dual-loaded photo- and chemo-active keratin nanoparticles as a novel drug delivery system to treat osteosarcoma. The nanoparticles are prepared from high molecular weight and hydrosoluble keratin, suitably functionalized with the photosensitizer Chlorin-e6 (Ce6) and then loaded with the chemotherapeutic drug Paclitaxel (PTX). This multi-modal PTX-Ce6@Ker nanoformulation is prepared by both drug-induced aggregation and desolvation methods, and a comprehensive physicochemical characterization is performed. PTX-Ce6@Ker efficacy is tested on osteosarcoma tumor cell lines, including chemo-resistant cells, using 2D and 3D model systems. The single and combined contributions of PTX and Ce6 is evaluated, and results show that PTX retains its activity while being vehiculated through keratin. Moreover, PTX and Ce6 act in an additive manner, demonstrating that the combination of the cytostatic blockage of PTX and the oxidative damage of ROS upon light irradiation have a far superior effect compared to singularly administered PTX or Ce6. Our findings provide the proof of principle for the development of a novel, nanotechnology-based drug delivery system for the treatment of osteosarcoma.

Genetic testing for high-grade osteosarcoma: a guide for future tailored treatments?

INTRODUCTION

Genetic characterization of osteosarcoma has evolved during the last decade, thanks to the integrated application of conventional and new candidate-driven and genome-wide technologies. Areas covered: This review provides an overview of the state of art in genetic testing applied to osteosarcoma, with particular regard to novel candidate genetic biomarkers that can be analyzed in tumor tissue and blood samples, which might be used to predict toxicity and prognosis, detect disease relapse, and improve patients' selection criteria for tailoring treatment. Expert commentary: Genetic testing based on modern technologies is expected to indicate new osteosarcoma-related prognostic markers and driver genes, which may highlight novel therapeutic targets and patients stratification biomarkers. The definition of tailored or targeted treatment approaches may improve outcome of patients with localized tumors and, even more, of those with metastatic disease, for whom progress in cure probability is highly warranted.

SUMO-specific protease 2 (SENP2) functions as a tumor suppressor in osteosarcoma via SOX9 degradation

Osteosarcoma (OS) is the most common primary bone malignancy in children and adolescents, the pathogenesis of which remain largely unknown. Small ubiquitin-like modifier (SUMO)-Specific Protease 2 (SENP2) has been reported to serve as a tumor suppressor in hepatocellular carcinoma cells. The aim of the present study was to investigate the critical role of SENP2 in OS cells. Using reverse transcription-quantitative polymerase chain reaction and western blot assays, it was observed that SENP2 was significantly downregulated in clinical OS tissues compared with adjacent normal samples. Ectopic expression of SENP2 resulted in the suppression of proliferation, migration and invasion in OS cells, whereas SENP2 knockdown by CRISPR-Cas9-based gene editing had the opposite effect. SENP2 is associated with the proteasome-dependent ubiquitination and degradation of SRY-box-9 (SOX9). SOX9 silencing impaired SENP2-depletion-induced accelerated cell growth and migration. Together, these results suggest that SOX9 is a critical downstream effector of the tumor suppressor SENP2 in OS.

The effect of ERCC1 and ERCC2 gene polymorphysims on response to cisplatin based therapy in osteosarcoma patients

Background

Cisplatin is one of the major drugs that used in the treatment of osteosarcoma. Cisplatin exerts its function by making cisplatin-DNA adducts culminating in cellular death. These adducts found to be repaired by nucleotide excision repair (NER) pathway. This study aimed to evaluate if polymorphisms in two main genes in the NER pathway, excision repair cross-complementing group 1 and 2 (ERCC1 and ERCC2) could affect the histological response to cisplatin based chemotherapy or clinical outcomes, particularly, event free survival (EFS) and overall survival (OS) rates.

Method

ERCC1 (C118T (rs11615) and C8092A (rs3212986)) and ERCC2 (A751C (rs171140) and G312A (rs1799793)) polymorphisms were analysed in 44 patients with osteosarcoma, who were treated with cisplatin based neoadjuvant chemotherapy. DNA was extracted from patient’s formalin-fixed paraffin-embedded (FFPE) samples, patient’s genotypes were determined by using polymerase chain reaction-restriction fragment length polymorphism PCR-RFLP assay. The distribution of the patients’ genotype and the allele frequencies were reported. The association between each of these genotypes and many clinical and patho-histological parameters (e.g. EFS, OS and patho-histological response to treatment) was examined. The associations between gender, tumor location, presence of metastasis at diagnosis, histological subtypes, and type of neoadjuvant chemotherapy and between the histological response, EFS and OS rates were also examined.

Results

This study revealed that there was a positive and significant association between ERCC1 C8092 A genotypes and median EFS rate in years; patients who were carriers of C allele (CC & CA) were found to have longer EFS rates than patients with AA genotype (P value = 0.006) and the median EFS rates were respectively as following: 2.04, 0.24 years. As well, both the presence of metastasis and the histological subtype at the time of diagnosis, were able to affect the EFS rate but not the OS. However, there was a positive correlation between OS rate and the patients’ primary response to treatment.

Conclusions

Our results suggested that ERCC1 8092 C allele may play a role as a candidate prognostic marker in patients with osteosarcoma.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0627-4) contains supplementary material, which is available to authorized users.

Candidate germline polymorphisms of genes belonging to the pathways of four drugs used in osteosarcoma standard chemotherapy associated with risk, survival and toxicity in non-metastatic high-grade osteosarcoma

This study aimed to identify associations between germline polymorphisms and risk of high-grade osteosarcoma (HGOS) development, event-free survival (EFS) and toxicity in HGOS patients treated with neo-adjuvant chemotherapy and surgery.

Germline polymorphisms of 31 genes known to be relevant for transport or metabolism of all four drugs used in HGOS chemotherapy (methotrexate, doxorubicin, cisplatin and ifosfamide) were genotyped in 196 patients with HGOS and in 470 healthy age and gender-matched controls. Of these 196 HGOS patients, a homogeneously treated group of 126 patients was considered for survival analyses (survival cohort). For 57 of these, treatment-related toxicity data were available (toxicity cohort).

Eleven polymorphisms were associated with increased risk of developing HGOS (p < 0.05). The distribution of polymorphisms in patients was characterized by a higher Shannon entropy. In the survival cohort (n = 126, median follow-up = 126 months), genotypes of ABCC2_1249A/G, GGH_452T/C, TP53_IVS2+38G/C and CYP2B6*6 were associated with EFS (p < 0.05). In the toxicity cohort (n = 57), genotypes of ABCB1_1236T/C, ABCC2_1249A/G, ABCC2_3972A/G, ERCC1_8092T/G, XPD_23591A/G, XRCC3_18067T/C, MTHFR_1298A/C and GGH_16T/C were associated with elevated risk for toxicity development (p < 0.05).

The results obtained in this retrospective study indicate that the aforementioned germline polymorphisms significantly impact on the risk of HGOS development, EFS and the occurrence of chemotherapy-related toxicity. These findings should be prospectively validated with the aim of optimizing and tailoring HGOS treatment in the near future.

Long non-coding RNA CTA sensitizes osteosarcoma cells to doxorubicin through inhibition of autophagy

Recently, several long non-coding RNAs (lncRNAs) have been implicated in osteosarcoma (OS). However, the regulatory roles of lncRNAs in chemotherapy resistance of OS still remain unclear. This study aimed to screen a novel lncRNA that contributes to chemotherapeutic resistance of OS, and to explore the underlying mechanisms. Our data showed that lncRNA CTA was markedly downregulated in OS tissues compared to their matched non-tumor tissues, and low expression of lncRNA CTA was significantly associated with the advanced clinical stage and tumor size. In addition, OS patients with low lncRNA CTA levels showed a worse prognosis when compared with those with high expression of lncRNA CTA. Furthermore, we report that lncRNA CTA has an inverse relationship with miR-210 expression in OS tissues. LncRNA CTA could be activated by doxorubicin (DOX), and could promote OS cell apoptosis by competitively binding miR-210, while inhibit cell autophagy. On the other hand, lncRNA CTA was downregulated in DOX-resistant OS cells. Overexpression of lncRNA CTA reduced autophagy and subsequently overcame DOX resistance of OS in vitro and in vivo. Therefore, we demonstrate that lncRNA CTA is an essential regulator in DOX-induced OS cell apoptosis, and the lncRNA CTA-miR-210 axis plays an important role in reducing OS chemoresistance.

Novel smoothened antagonists as anti-neoplastic agents for the treatment of osteosarcoma

Osteosarcoma (OS) is an ultra-rare highly malignant tumor of the skeletal system affecting mainly children and young adults and it is characterized by an extremely aggressive clinical course. OS patients are currently treated with chemotherapy and complete surgical resection of cancer tissue. However, resistance to chemotherapy and the recurrence of disease, as pulmonary metastasis, remain the two greatest challenges in the management, and treatment of this tumor. For these reasons, it is of primary interest to find alternative therapeutic strategies for OS. Dysregulated Hedgehog signalling is involved in the development of various types of cancers including OS. It has also been implicated in tumor/stromal interaction and cancer stem cell biology, and therefore presents a novel therapeutic strategy for cancer treatment. In our work, we tested the activity of five potent Smoothened (SMO) inhibitors, four acylguanidine and one acylthiourea derivatives, against an OS cell line. We found that almost all our compounds were able to inhibit OS cells proliferation and to reduce Gli1 protein levels. Our results also indicated that SMO inhibition in OS cells by such compounds, induces apoptosis with a nanomolar potency. These findings suggest that inactivation of SMO may be a useful approach to the treatment of patients with OS.