The role of chemotherapy for metastatic, relapsed and refractory osteosarcoma

Spatial multiplexed immunofluorescence analysis reveals coordinated cellular networks associated with overall survival in metastatic osteosarcoma

Patients diagnosed with advanced osteosarcoma, often in the form of lung metastases, have abysmal five-year overall survival rates. The complexity of the osteosarcoma immune tumor microenvironment has been implicated in clinical trial failures of various immunotherapies. The purpose of this exploratory study was to spatially characterize the immune tumor microenvironment of metastatic osteosarcoma lung specimens. Knowledge of the coordinating cellular networks within these tissues could then lead to improved outcomes when utilizing immunotherapy for treatment of this disease. Importantly, various cell types, interactions, and cellular neighborhoods were associated with five-year survival status. Of note, increases in cellular interactions between T lymphocytes, positive for programmed cell death protein 1, and myeloid-derived suppressor cells were observed in the 5-year deceased cohort. Additionally, cellular neighborhood analysis identified an Immune-Cold Parenchyma cellular neighborhood, also associated with worse 5-year survival. Finally, the Osteosarcoma Spatial Score, which approximates effector immune activity in the immune tumor microenvironment through the spatial proximity of immune and tumor cells, was increased within 5-year survivors, suggesting improved effector signaling in this patient cohort. Ultimately, these data represent a robust spatial multiplexed immunofluorescence analysis of the metastatic osteosarcoma immune tumor microenvironment. Various communication networks, and their association with survival, were described. In the future, identification of these networks may suggest the use of specific, combinatory immunotherapeutic strategies for improved anti-tumor immune responses and outcomes in osteosarcoma.

CircUSP48 promotes malignant behavior by regulating CYR61 via miR-365 in osteosarcoma

Even though circular RNAs (circRNAs), a class of non-coding endogenous RNA, play a crucial role in the progression of osteosarcoma (OS), the specific function of hsa_circ_0000028 (circUSP48) remains unclear. This study aims to elucidate the mechanism by which circUSP48 regulates OS. We employed qRT-PCR and western blot techniques to quantify circDOCK1, miR-186, and DNMT3A levels. Cell proliferation was assessed using the cell counting kit-8 (CCK-8), 5-Ethynyl-20-deoxyuridine (EdU) assay, and colony formation assay. Cell migration and invasion were evaluated through Transwell and cell scratch assays. Furthermore, we performed dual-luciferase reporter, RIP, and RNA pull-down assays to investigate the association between circUSP48, miR-365, and CYR61. In addition, an in vivo xenograft model was utilized to assess the functional role of circUSP48. High levels of circUSP48 and CYR61 were observed in OS tissues and cells, while miR-365 levels were low. Knockdown of circUSP48 suppressed the multiplication, motility, and invasion of OS cells, thereby reducing carcinoma growth. Moreover, inhibition of miR-365 reversed the OS cell-suppressive effect caused by circUSP48 knockdown through direct interaction with circUSP48. Additionally, circUSP48 upregulated the expression of CYR61 by sponging miR-365. The findings suggest that circUSP48 promotes malignant behavior in OS by regulating the expression of CYR61 through miR-365, making it a potential therapeutic target for OS.

Potential target identification for osteosarcoma treatment: Gene expression re-analysis and drug repurposing

Survival rate of osteosarcoma has remained plateaued for the past three decades. New treatment is needed to improve survival rate. Drug repurposing, a method to identify new indications of previous drugs, which saves time and cost compared to the de novo drug discovery. Data mining from gene expression profile was carried out and new potential targets were identified by using drug repurposing strategy. Selected data were newly categorized as pathophysiology and metastasis groups. Data were normalized and calculated the differential gene expression. Genes with log fold change ≥ 2 and adjusted p-value ≤ 0.05 were selected as primary candidate genes (PCGs). PCGs were further enriched to determine the secondary candidate genes (SCGs) by protein interaction analysis, upstream transcription factor and related-protein kinase identification. PCGs and SCGs were further matched with gene targeted of corresponding drugs from the Drug Repurposing Hub. A total of 778 targets were identified (360 from PCGs, and 418 from SCGs). This newly identified KLHL13 is a new candidate target based on its molecular function. KLHL13 was upregulated in clinical samples. We found 256 drugs from matching processes (50anti-cancerand206non-anticancerdrugs). Clinical trials of anti-cancer drugs from 5 targets (CDK4, BCL-2, JUN, SRC, PIK3CA) are being performed for osteosarcoma treatment. Niclosamide and synthetic PPARɣ ligands are candidates for repurposing due to the possibility based on their mechanism and pharmacology properties. Re-analysis of gene expression profile could identify new potential targets, confirm a current implication, and expand the chance of repurposing drugs for osteosarcoma treatment.

PET-CT in Clinical Adult Oncology-VI. Primary Cutaneous Cancer, Sarcomas and Neuroendocrine Tumors

PET-CT is an advanced imaging modality with many oncologic applications, including staging, therapeutic assessment, restaging and surveillance for recurrence. The goal of this series of six review articles is to provide practical information to providers and imaging professionals regarding the best use of PET-CT for specific oncologic indications, the potential pitfalls and nuances that characterize these applications, and guidelines for image interpretation. Tumor-specific clinical information and representative PET-CT images are provided. The current, sixth article in this series addresses PET-CT in an evaluation of aggressive cutaneous malignancies, sarcomas and neuroendocrine tumors. A discussion of the role of FDG PET for all types of tumors in these categories is beyond the scope of this review. Rather, this article focuses on the most common malignancies in adult patients encountered in clinical practice. It also focuses on Food and Drug Agency (FDA)-approved and clinically available radiopharmaceuticals rather than research tracers or those requiring a local cyclotron. This information will serve as a guide to primary providers for the appropriate role of PET-CT in managing patients with cutaneous malignancies, sarcomas and neuroendocrine tumors. The nuances of PET-CT interpretation as a practical guide for imaging providers, including radiologists, nuclear medicine physicians and their trainees, are also addressed.

Clinicopathological value of the upregulation of cyclin-dependent kinases regulatory subunit 2 in osteosarcoma

Background

Cyclin-dependent kinase subunit 2 (CKS2) is a member of cyclin dependent kinase subfamily and the relationship between CKS2 and osteosarcoma (OS) remains to be further analyzed.

Methods

80 OS and 41 non-tumor tissue samples were arranged to perform immunohistochemistry (IHC) to evaluate CKS2 expression between OS and non-tumor samples. The standard mean deviation (SMD) was calculated based on in-house IHC and tissue microarrays, and exterior high-throughput datasets for further verification of CKS2 expression trend in OS. The effect of CKS2 expression on clinicopathological parameters of OS patients, and single-cell in OS tissues was analyzed through public high-throughput datasets and functional enrichment analysis was conducted for co-expression genes of CKS2 in accordance with weighted correlation network analysis.

Results

A total of 217 OS samples and 87 non-tumor samples (including tissue and cell line) were obtained from in-house IHC, microarrays and exterior high-throughput datasets. The analysis of integrated expression status demonstrated up-regulation of CKS2 in OS (SMD = 1.57, 95%CI [0.27–2.86]) and the significant power of CKS2 expression in distinguishing OS samples from non-tumor samples (AUC = 0.97 95%CI [0.95–0.98]). Clinicopathological analysis of GSE21257 indicated that OS patients with higher CKS2 expression was more likely to suffer OS metastasis. Although Kaplan–Meier curves showed no remarkable difference of overall survival rate between OS patients with high and low-CKS2, CKS2 was found up-regulated in proliferating osteosarcoma cells. Co-expression genes of CKS2 were mainly assembled in function and pathways such as cell cycle, cell adhesion, and intercellular material transport.

Conclusions

In summary, up-regulation of CKS2 expression in OS tissue was found through multiple technical approaches. In addition, scRNA-seq and co-expression analysis showed that CKS2 may have an impact on important biological process linked with cell cycle, cell adhesion, and intercellular material transport. Present study on CKS2 in OS indicated a promising prospect for CKS2 as a biomarker for OS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01234-8.

Overexpression of Long Non-Coding RNA MIR22HG Represses Proliferation and Enhances Apoptosis via miR-629-5p/TET3 Axis in Osteosarcoma Cells

In this study, we evaluated the mechanism of long non-coding RNA MIR22 host gene (LncRNA MIR22HG) in osteosarcoma cells. Forty-eight paired osteosarcoma and adjacent tissues samples were collected and the bioinformatic analyses were performed. Target genes and potential binding sites of MIR22HG, microRNA (miR)-629-5p and tet methylcytosine dioxygenase 3 (TET3) were predicted by Starbase and TargetScan V7.2 and confirmed by dual-luciferase reporter assay. Cell Counting Kit-8, colony formation and flow cytometry assays were utilized to determine the viability, proliferation and apoptosis of transfected osteosarcoma cells. Pearson's analysis was introduced for the correlation analysis between MIR22HG and miR-629-5p in osteosarcoma tissue. Relative expressions of MIR22HG, miR-629-5p and TET3 were measured by quantitative real-time polymerase chain reaction or Western blot. MiR-629-5p could competitively bind with and was negatively correlated with MIR22HG, the latter of which was evidenced by the high expression of miR-629-5p and low expression of MIR22HG in osteosarcoma tissues. Overexpressed MIR22HG repressed the viability and proliferation but enhanced apoptosis of osteosarcoma cells, which was reversed by miR-629-5p upregulation. TET3 was the target gene of miR-629-5p, and the promotive effects of upregulated miR-629-5p on the viability and proliferation as well as its repressive effect on apoptosis were abrogated via overexpressed TET3. To sum up, overexpressed MIR22HG inhibits the viability and proliferation of osteosarcoma cells, which was achieved via regulation of the miR-629-5p/TET3 axis.

Research Progress of MicroRNA in Chemotherapy Resistance of Osteosarcoma

Osteosarcoma (OS) is a malignant tumor prevalent in adolescents; however, a clinically effective treatment for this malignancy is lacking. The lack of effective treatment methods and factors, such as recurrence and drug resistance, further dampen the prospect of clinically treating OS. In recent years, small molecule microRNAs (miRNAs) with a length of approximately 20-24 nucleotides have gradually attracted the attention of the medical community. Studies have found that miRNAs can regulate the cell cycle, apoptosis, cell proliferation, and cell proliferation. The metabolic response of cancer cells, invasion and metastasis of cancer cells, and angiogenesis play an important role in the process of tumorigenesis. miRNAs regulate gene expression by regulating mRNA expression after transcription. A large amount of data from many studies indicate that they have diagnostic and prognostic biomarker effects in OS and are involved in regulating the metabolism of cancer cells and resistance or sensitivity to chemotherapy drugs. Chemotherapy resistance is one of the most critical problems in clinically treating OS. A large number of basic studies and systematic summaries are required to provide a theoretical basis for elucidating the mechanism and drug development of chemotherapeutic agents. Therefore, this article discusses the role of miRNAs in OS resistance. Herein, the related research progress of the studies is reviewed to provide more useful information for the development of effective therapy.

Systematic Review of Recurrent Osteosarcoma Systemic Therapy

Osteosarcoma is the most frequent primary bone cancer, mainly affecting those of young ages. Although surgery combined with cytotoxic chemotherapy has significantly increased the chances of cure, recurrent and refractory disease still impose a tough therapeutic challenge. We performed a systematic literature review of the available clinical evidence, regarding treatment of recurrent and/or refractory osteosarcoma over the last two decades. Among the 72 eligible studies, there were 56 prospective clinical trials, primarily multicentric, single arm, phase I or II and non-randomized. Evaluated treatment strategies included cytotoxic chemotherapy, tyrosine kinase and mTOR inhibitors and other targeted agents, as well as immunotherapy and combinatorial approaches. Unfortunately, most treatments have failed to induce objective responses, albeit some of them may sustain disease control. No driver mutations have been recognized, to serve as effective treatment targets, and predictive biomarkers of potential treatment effectiveness are lacking. Hopefully, ongoing and future clinical and preclinical research will unlock the underlying biologic mechanisms of recurrent and refractory osteosarcoma, expanding the therapeutic choices available to pre-treated osteosarcoma patients.

Circ_WWC3 overexpression decelerates the progression of osteosarcoma by regulating miR-421/PDE7B axis

Background

Emerging evidence has shown that circular RNAs (circRNAs) are vital regulators in osteosarcoma (OS) progression. However, the effects of circ_WWC3 in OS have not been explored. In this research, the functions and mechanisms of circ_WWC3 in OS were investigated.

Methods

Quantitative reverse trancription polymerase chain reaction (qRT-PCR) was adopted to determine the levels of circ_WWC3, WW and WWC3 mRNA, miR-421, and phosphodiesterase 7B (PDE7B) mRNA. RNase R assay was used to determine the characteristic of circ_WWC3. Colony formation assay and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay were applied for cell growth. Transwell assay was performed for cell migration and invasion. Flow cytometry analysis was utilized for cell apoptosis. Western blot assay was conducted for the levels of apoptosis-related proteins and PDE7B protein. Dual-luciferase reporter assay was carried out to analyze the targeting relationship between miR-421 and circ_WWC3 or PDE7B. The murine xenograft model was established to explore the effect of circ_WWC3 in vivo.

Results

Compared to normal tissues and cells, circ_WWC3 and PDE7B were downregulated in OS tissues and cells. Overexpression of circ_WWC3 or PDE7B suppressed OS cell growth, migration, and invasion and promoted apoptosis in vitro. Regarding the mechanism analysis, circ_WWC3 positively modulated PDE7B expression by targeting miR-421. MiR-421 overexpression restored the impacts of circ_WWC3 on OS cell growth, metastasis, and apoptosis. Inhibition of miR-421 repressed the malignant behaviors of OS cells by targeting PDE7B. In addition, circ_WWC3 inhibited the tumorigenicity of OS in vivo.

Conclusion

Circ_WWC3 overexpression slowed the development of OS by elevating PDE7B via sponging miR-421.

Cardamonin inhibits the growth of human osteosarcoma cells through activating P38 and JNK signaling pathway

Osteosarcoma (OS) is the most common type of bone malignant tumors. Clinical commonly used therapeutic drugs of OS treatment are prone to toxic and side effects, so it is very urgent to develop new drugs with low toxicity and low side effects. As a Chinese herbal medicine, Cardamonin (CAR) (C16H14O4) has inhibitory effects in various tumors. In the present study, we investigated the effects of CAR on OS cells in vitro and in vivo. We found that CAR inhibited cell proliferation, reduced migration, decreased invasion, and induced G2 / M arrest of OS cells. Notably, we demonstrated that CAR had no obvious effect on proliferation and apoptosis of normal cells. Besides, CAR repressed tumor growth of OS cells in xenograft mouse model. Mechanically, we found that CAR increased the phosphorylation level of P38 and JNK. In summary, our research validates that CAR may inhibit the proliferation, migration, and invasion of OS and promote apoptosis possibly by activating P38 and JNK Mitogen-activated protein kinase (MAPK) signaling pathway.

Identification and Analysis of Three Hub Prognostic Genes Related to Osteosarcoma Metastasis

Osteosarcoma (OS) often occurs in children and often undergoes metastasis, resulting in lower survival rates. Information on the complexity and pathogenic mechanism of OS is limited, and thus, the development of treatments involving alternative molecular and genetic targets is hampered. We categorized transcriptome data into metastasis and nonmetastasis groups, and 400 differential RNAs (230 messenger RNAs (mRNAs) and 170 long noncoding RNAs (lncRNAs)) were obtained by the edgeR package. Prognostic genes were identified by performing univariate Cox regression analysis and the Kaplan-Meier (KM) survival analysis. We then examined the correlation between the expression level of prognostic lncRNAs and mRNAs. Furthermore, microRNAs (miRNAs) corresponding to the coexpression of lncRNA-mRNA was predicted, which was used to construct a competitive endogenous RNA (ceRNA) regulatory network. Finally, multivariate Cox proportional risk regression analysis was used to identify hub prognostic genes. Three hub prognostic genes (ABCG8, LOXL4, and PDE1B) were identified as potential prognostic biomarkers and therapeutic targets for OS. Furthermore, transcriptions factors (TFs) (DBP, ESX1, FOS, FOXI1, MEF2C, NFE2, and OTX2) and lncRNAs (RP11-357H14.16, RP11-284N8.3, and RP11-629G13.1) that were able to affect the expression levels of genes before and after transcription were found to regulate the prognostic hub genes. In addition, we identified drugs related to the prognostic hub genes, which may have potential clinical applications. Immunohistochemistry (IHC) and quantitative real-time polymerase chain reaction (qRT-PCR) confirmed that the expression levels of ABCG8, LOXL4, and PDE1B coincided with the results of bioinformatics analysis. Moreover, the relationship between the hub prognostic gene expression and patient prognosis was also validated. Our study elucidated the roles of three novel prognostic biomarkers in the pathogenesis of OS as well as presenting a potential clinical treatment for OS.

circUBAP2 regulates osteosarcoma progression via the miR‑204‑3p/HMGA2 axis

Circular RNA (circRNA/circ)-ubiquitin associated protein 2 (UBAP2), a newly recognized circRNA, serves a functional role in several types of tumor, including ovarian cancer, colorectal cancer and osteosarcoma. However, the precise roles and molecular mechanism under-lying circUBAP2 in osteosarcoma (OS) are not completely understood. In the present study, the expression levels of circUBAP2, microRNA (miR)-204-3p and (HMGA2) were evaluated via reverse transcription-quantitative PCR in OS tissues and cells. OS cell proliferation, migration, invasion and apoptosis were assessed by performing Cell Counting Kit-8, Transwell and flow cytometry assays, respectively. HMGA2 protein expression levels were determined via western blot-ting. Dual-luciferase reporter assays were performed to verify the interaction between circUBAP2 and miR-204-3p, and between miR-204-3p and HMGA2. An RNA immunoprecipitation (RIP) assay was conducted to confirm the interaction between circUBAP2 and miR-204-3p. The results demonstrated that circUBAP2 expression was significantly upregulated in OS tissues and cell lines compared with para-cancerous tissues and hFOB1.19 cells, respectively. In addition, high circUBAP2 expression levels in patients with OS were associated with a lower survival rate compared with lower expression levels in patients with OS. The functional assays revealed that circUBAP2 knockdown significantly inhibited OS cell proliferation, migration and invasion, but increased OS cell apoptosis compared with the small interfering RNA-negative control (si-NC) group. The dual-luciferase reporter and RIP assay results confirmed that circUBAP2 bound to miR-204-3p. Moreover, miR-204-3p expression was significantly downregulated in OS tissues compared with paracancerous tissues, and miR-204-3p expression was negatively correlated with circUBAP2 expression in OS tissues. Collectively, the results demonstrated that miR-204-3p was associated with circUBAP2 knockdown-mediated inhibition of OS cell malignant behavior. Moreover, miR-204-3p was also identified as one of the direct targets of HMGA2. Collectively, the results indicated that compared with the si-NC group, circUBAP2 knockdown significantly inhibited OS cell malignant behavior by binding to miR-204-3p, which subsequently regulated HMGA2 expression. Therefore, the present study demonstrated that circUBAP2 expression was upregulated in OS, and circUBAP2 regulated OS cell malignant behavior via the miR-204-3p/HMGA2 axis.

Gemcitabine and Rapamycin Exhibit Additive Effect against Osteosarcoma by Targeting Autophagy and Apoptosis

The overall prognosis for sarcoma-based cancer patients has remained largely unchanged over the past 10 years. Because there is no effective anticancer drug for patients with chemoresistant osteosarcoma (OS), novel approaches are needed to improve the prognosis. Here, we investigated whether rapamycin (Rapa) could enhance the anti-tumor effects of gemcitabine (Gem) in OS. Gem dose-dependently killed the OS cells, but exhibited much lower cytotoxicity on osteoblasts. Treatment with a combination Gem and Rapa was much more effective than that of either single agent with respect to reducing cell viability, cell invasion, cell migration, and vascular endothelial growth factor production in vitro. Moreover, the combination of these agents suppressed tumor growth, angiogenesis, and lung metastasis in allograft and xenograft murine models of OS with minimal adverse effects. Overall, the combination therapy prolonged the overall survival of tumor-bearing mice. Mechanistically, Gem induced apoptosis and increased the levels of cleaved caspases, while Rapa induced autophagy and microtubule-associated protein light chain 3 (LC3)-I/LC3-II expression both in vitro and in vivo. Our findings suggest that chemotherapy using Gem combined with Rapa may be a novel and promising therapeutic approach for the treatment of OS.

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

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

One-stop radiotherapeutic targeting of primary and distant osteosarcoma to inhibit cancer progression and metastasis using 2DG-grafted graphene quantum dots

The application of radiotherapy (RT) to treat osteosarcoma (OS) has been limited, but this is starting to change as the ability to target radiation energy to niches improves. Furthermore, lung cancer from highly metastatic OS is a major cause of death, so it is critical to explore new strategies to tackle metastasis. In this study, we designed a nanoscale radiosensitizer by grafting 2-deoxy-d-glucose (2DG) onto graphene quantum dots (GQD) to achieve OS targeting and boost RT efficacy. Combining the use of 2DG-grafted GQDs (2DG-g-GQD) with RT produced a significant increase in oxidative stress response and DNA damage in the 143B OS cell line compared with RT alone. Moreover, 2DG-g-GQDs selectively associated with 143B cells, and demonstrated the inhibition of migration in a scratch assay. We also demonstrated remarkable improvement in their ability to inhibit tumour progression and lung metastasis in an OS xenograft mouse model. Our results show that the use of 2DG-g-GQDs as OS-targeting radiosensitizers improves their therapeutic outcome and exhibits potential for use in low-dose precision RT for OS.

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.

Apatinib ameliorates doxorubicin-induced migration and cancer stemness of osteosarcoma cells by inhibiting Sox2 via STAT3 signalling

Background

Osteosarcoma, ranking as the second primary cause of cancer-related death, is the most common type of bone cancer. Doxorubicin (DOX) is used as a first-line treatment for osteosarcoma; however, the tumour recurrence rate remains high. Recent studies have suggested that DOX-induced migration and stemness in osteosarcoma cells might be the primary reason of recurrence and drug resistance. However, the underlying mechanisms remain unclear. Therefore, it is urgent to explore novel effective treatments to overcome DOX-induced drug resistance of osteosarcoma.

Methods

Osteosarcoma cells KHOS and U2OS were treated with DOX and apatinib (AP) alone or in combination. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and colony formation assays were performed to evaluate effects on proliferation. Flow cytometry analysis was carried out to assess cell apoptosis. Cell migration was determined by the transwell assay. Cancer stemness was detected by flow cytometry analysis of CD133⁺ cells and sphere-formation assay. Western blot assay was used to measure the expression of E-cadherin, N-cadherin, vimentin, matrix metalloproteinase 9 (MMP-9), signal transducer and activator of transcription 3 (STAT3)/p-STAT3, SRY-box2 (Sox2) and octamer-binding protein 4 (Oct4), and Nanog in treated osteosarcoma cells.

Results

Herein, we revealed that AP treatment significantly enhanced the sensitivity of osteosarcoma cells to DOX, reversed the DOX-induced stemness phenotype and metastasis capacity of osteosarcoma cells, and abolished the upregulation of p-STAT3, Sox2, Oct4, and Nanog. We further demonstrated that AP reversed DOX-induced stemness and migration of osteosarcoma cells through Sox2.

Conclusion

These results suggested that AP significantly abolished the DOX-induced stemness phenotype and metastasis capacity in osteosarcoma cells by inhibiting Sox2 via STAT3 signalling.

The translational potential of this article

Our study indicates that Doxorubicin-based chemotherapeutics may simulate cancer stem cells (CSCs) properties in osteosarcoma, leading to the resistance of osteosarcoma. Apatinib can reduce the Doxorubicin-induced chemoresistance through STAT3/Sox2 pathway inactivation. This study represents that Apatinib may act as an effective chemotherapy sensitiser for reducing chemoresistance correlated with CSCs in osteosarcoma.

The association of XRCC1 polymorphism with osteosarcoma risk, clinicopathologic features, and prognosis in a Chinese Han population

Introduction

The association of single-nucleotide polymorphisms at X-ray repair cross-complementing group-1 (XRCC1) with osteosarcoma (OS) development has not been fully clear to date. The aim of the present study is to evaluate the association of XRCC1 polymorphisms with risk, clinicopathologic features, and prognosis in Chinese OS patients.

Methods

A total of 146 patients with primary OS and 248 age- and gender-matched controls were included in the present study. The frequencies of four XRCC1 polymorphisms (rs25487, rs1799782, rs25489, and rs3213245) were determined between OS patients and controls. The association of XRCC1 polymorphism with clinicopathologic characteristics, prognosis, and XRCC1 expression was further evaluated.

Results

Compared with TT genotype, individuals carrying the minor C allele (TC+ CC) of rs3213245 had significantly increased risk of OS development (OR =1.83, 95% CI 1.14–3.00). OS patients carrying TC genotype and C allele at rs3213245 were more likely to be with larger tumor size and metastasis. Survival analysis demonstrated that OS patients carrying C allele (TC + CC) at rs3213245 had shorter survival time than those with TT genotype. The T to C substitution at rs3213245 could decrease XRCC1 gene transcriptional activity in vitro. XRCC1 mRNA and protein expression levels were lower in OS patients carrying TC or CC genotype at rs3213245. Besides, no significant association of rs25487, rs1799782, and rs25489 with OS was observed.

Conclusion

In conclusion, these findings revealed that XRCC1 rs3213245 polymorphism was associated with increased risk of OS, which could affect XRCC1 expression in vitro and in vivo.

Knockdown of MALAT1 inhibits osteosarcoma progression via regulating the miR‑34a/cyclin D1 axis

Long non-coding (lnc)RNAs have been demonstrated to be involved in the development of various types of cancers, such as osteosarcoma (OS). Long non-coding (lnc) RNA metastasis associated lung adenocarcinoma transcript 1 (MALAT1) expression was reported to be highly expressed in OS and promoted the development of this disease; however, the underlying molecular mechanism by which MALAT1 promotes the progression of OS requires further investigation. In the present study, the expression of MALAT1 and miR-34a was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The abundance of cyclin D1 (CCND1) was detected by RT-qPCR and western blotting. Cell viability, migration and invasion were examined by MTT and Transwell assays. The interaction between miR-34a and MALAT1 or CCND1 was probed by a dual luciferase reporter assay and RNA immunoprecipitation. Xenograft tumor assay was performed to verify the roles of MALAT1 and miR-34a in tumor growth in vivo. The results demonstrated that MALAT1 and CCND1 mRNA expression levels were upregulated and miR-34a was downregulated in OS tissues and cells. Additionally, MALAT1 expression was correlated with tumor size, clinical stage and distant metastasis in patients with OS. In addition, MALAT1 promoted OS cell viability, invasion and migration, while MALAT1 silencing exhibited opposing effects. Moreover, MALAT1 functioned as a ceRNA to suppress miR-34a expression and in turn upregulate CCND1 in OS cells. Rescue experiments further demonstrated that MALAT1 knockdown partially reversed anti-miR-34a-mediated promotion on OS cell viability, migration and invasion; overexpression of CCND1 partially reversed the effects of MALAT1 silencing on OS progression. Furthermore, in vivo experiments also revealed that MALAT1 promoted OS tumor growth via miR-34a inhibition and upregulating the expression of CCND1. In conclusion, the present study suggested that MALAT1 exerted its oncogenic function in OS by regulating the miR-34a/CCND1 axis in OS, which may provide novel insight into the diagnosis and therapy for OS.

Combination of gemcitabine and docetaxel: a regimen overestimated in refractory metastatic osteosarcoma?

Background

The combination of gemcitabine and docetaxel (GT) has been demonstrated to be effective against various types of solid tumors, including sarcoma. However, the regimen has not been confirmed in large, well-designed clinical trials in refractory metastatic osteosarcoma.

Methods

We retrospectively reviewed the records of patients with refractory metastatic osteosarcoma at Peking University People’s Hospital who were treated with gemcitabine (1000 mg/m²) intravenously (IV) on Day 1 and Day 8, and docetaxel (75 mg/m²) IV on Day 8, repeated every 21 days.

Results

A total of 52 patients with a median age of 18.4 years were treated with GT at the Peking University People’s Hospital from August 2012 to August 2017. A total of 174 courses were administered. Only five patients with pulmonary metastasis achieved a best response of stable disease (SD), while all other patients had progressive disease. The result was disappointing with an ORR of 0%, a DCR of 9.6%, and a median DOR of 3.5 months. Grade 3 or 4 toxicities were observed in 69 (39.7%) courses and in 28 (53.8%) patients, most of which were myelosuppression, especially thrombocytopenia. No fatal adverse effect (AE) was found.

Conclusion

The combination of gemcitabine and docetaxel (GT) as a salvage regimen is well-tolerated but not as effective as expected in refractory metastatic osteosarcoma. This report highlights the need for the development of new approaches with higher activity in these patients.

Synergistic effect of docetaxel combined with cisplatin on inhibiting human osteosarcoma in nude mice

Cisplatin (CDDP) has been shown to be a promising anticancer drug that is effective against many types of cancer, which include osteosarcoma (OS). However, its therapeutic application is restricted by its toxicity in normal tissues, side effects caused in patients, and chemotherapy resistance. Thus, to further improve patients' treatment, the development of novel, more effective and well tolerated therapeutic approaches against OS in clinical is urgent and important. In the present study, nude mice were inoculated subcutaneously with injections of HOS8603 cells, CDDP and docetaxel (DTX) were administered intraperitoneally respectively. The inhibitive effects and the side effects were observed. Tumor weights and volumes were significantly lower and the tumor inhibition rate was significantly higher in the combination group than those of either drug alone or vehicle. The cell density in the tumor tissue was significantly decreased, apoptotic and necrotic cell death was significantly increased in the combination group, as compared with those of either drug alone or vehicle. In addition, there was no obvious side effect happening besides the appearance of erythema and papules in some mice. These results suggest that the combined effects of CDDP and DTX on the growth of human OS in vivo were superior to the single effects. CDDP combined with DTX had synergistic effects at lower concentrations and promoted apoptosis, but did not increase the side effects of chemotherapy.

Long non-coding RNA SNHG5 sponges miR-26a to promote the tumorigenesis of osteosarcoma by targeting ROCK1

BACKGROUND

Osteosarcoma (OS) is one of the most common invasive malignancies of the bone. The long non-coding RNA (lncRNA) SNHG5 (small nucleolar RNA host gene 5) has been consistently shown to be involved in many cancers, although its precise function in osteosarcoma remains poorly understood. In this study, we investigated the role of SNHG5 in OS progression and the underlying mechanism.

METHODS

SNHG5 expression in 32 OS tissues and 4 OS cell lines was measured by quantitative real-time PCR (qRT-PCR). Migration, invasion, proliferation and cell cycle profiles were analyzed by established assays to determine the biological functions of SNHG5 and miR-26a in OS cells. The binding sites of miR-26a in SNHG5 and ROCK1 were predicted by the RNAhybrid 2.2 program. Luciferase reporter assay was then used to validate the direct targeting of SNHG5 with miR-26a and of Rho-associated coiled coil-containing protein kinase 1 (ROCK1) with miR-26a. The effect of SNHG5 on the ROCK signaling pathway was assessed by western blotting.

RESULTS

Elevated expression of SNHG5 was correlated with poor clinical outcome and prognosis in OS patients. SNHG5 functioned as a sponge for miR-26a and promoted proliferation, invasion and migration, and accelerated G1 to S phase transition in OS cells. SNHG5 functioned as a competing endogenous RNA (ceRNA) for miR-26a and activated the ROCK signaling pathway through the miR-26a-ROCK1 axis.

CONCLUSION

SNHG5 acts as an oncogene in OS via the SNHG5-miR-26a-ROCK1 axis and is therefore a potential novel therapeutic target for OS treatment.

Efficacy and safety of stereotactic radiosurgery for pulmonary metastases from osteosarcoma: Experience in 73 patients

Osteosarcoma pulmonary metastases are typically treated with resection and/or chemotherapy. We hypothesize that stereotactic radiosurgery (SRS) can be an alternative to surgery that can achieve high rates of local control with limited toxicity. From January 2005 to December 2013, 73 patients who developed pulmonary metastasis during period of adjuvant chemotherapy or follow-up were analyzed. 33 patients were treated by stereotactic radiosurgery using the body gamma-knife system. A total dose of 50 Gy was delivered at 5 Gy/fraction to the 50% isodose line covering the planning target volume, whereas a total dose of 70 Gy was delivered at 7 Gy/fraction to the gross target volume. The other 40 patients were treated by surgical resection. Four-year progression-free survival rate, four-year survival rate, median time of PRPFS (post-relapse progress-free survival) and PROS (post-relapse overall survival) in SRS group were parallel to that in surgical group. Patients tolerated gamma knife radiosurgery well. Our study demonstrates that SRS is well-tolerated with excellent local control and less complications. SRS should be considered as a potential option in patients with pulmonary metastases from osteosarcoma, especially in those who are medically inoperable, refuse surgery.

rs1760944 Polymorphism in the APE1 Region is Associated with Risk and Prognosis of Osteosarcoma in the Chinese Han Population

The effects of single nucleotide polymorphisms (SNPs) at APE1 have been investigated in several types of cancer. However, no reports of the association of APE1 polymorphisms with osteosarcoma (OS) have been published. The present study was designed to determine whether APE1 polymorphisms (rs1130409, rs1760944, rs1760941, rs2275008, rs17111750) are associated with OS. A 2-stage case-control study was performed in a total of 378 OS patients and 616 normal controls. Individuals carrying TG and GG genotypes had significantly lower risk of developing OS than those with the WT genotype TT at rs1760944 (OR = 0.65, 95%CI 0.49–0.86; OR = 0.50, 95%CI 0.34–0.74, respectively). OS patients with allele G at rs1760944 were less susceptible to low differentiation tumor and metastasis (OR = 0.73, 95%CI 0.54–0.98; OR = 0.63, 95%CI 0.43–0.92, respectively). Kaplan-Meier curves and log-rank results revealed that OS patients harboring genotype GG and G allele at rs1760944 had better survival (P < 0.001 for both). In addition, the APE1 protein was underexpressed in individuals who carried G allele at rs1760944. This study suggested that APE1 rs1760944 polymorphism is associated with decreased risk of developing OS and better survival of OS patients.

The synergistic antitumor effect of cinobufagin and cisplatin in human osteosarcoma cell line in vitro and in vivo

Cisplatin (CDDP) has been shown to be a promising anticancer drug that is effective against many types of cancer, which include osteosarcoma (OS). However, its therapeutic application is restricted by its toxicity in normal tissues and by side effects caused in patients. Reduction of the toxicity of CDDP is necessary to improve cancer treatment. In the present study, we attempted to clarify how cinobufagin, a traditional Chinese medicine, enhances CDDP-induced cytotoxicity in OS cells. OS 143B cells were treated with cinobufagin and CDDP alone or in combination. After low dose combined treatments with cinobufagin and CDDP, the effects of these therapeutics on cell proliferation, apoptosis, cell cycle, migration, invasion, and involvement in Notch pathway, as well as tumor growth and metastatic capability were determined. It was found that the combination of low doses of cinobufagin and CDDP markedly inhibited cell activity, motility, and induced apoptosis and cell cycle arrest in S phase, as well as suppressing tumor growth, metastasis and prolonging longer survival of nude mice in OS xenograft models compared with the actions of either drug alone or vehicle. The results also demonstrated that cinobufagin plus CDDP significantly suppressed the Notch pathway. The anticancer mechanism of these two drugs may involve intervention in the Notch signaling, which may contribute to inhibit tumor growth. All of these results suggest that application of lower concentration cinobufagin plus CDDP could produce a synergistic antitumor effect and this finding warrants further investigation for its potential clinical applications in human OS patients.

Antisense lncRNA FOXC2-AS1 promotes doxorubicin resistance in osteosarcoma by increasing the expression of FOXC2

Recent efforts have revealed that numerous natural antisense lncRNAs play a crucial role in the regulation of cancer biology. Here, based on our previous study, we further identified that the lncRNA FOXC2-AS1 and its antisense transcript FOXC2 are positively up-regulated in doxorubicin-resistant osteosarcoma cell lines and tissues, correlate with poor prognosis and promote doxorubicin resistance in osteosarcoma cells in vitro and in vivo. In addition, FOXC2-AS1 and FOXC2 are mainly located in the cytoplasm and form an RNA-RNA double-stranded structure in the overlapping region, which is necessary for FOXC2-AS1 to regulate the expression of FOXC2 at both the transcription and post-transcription levels. In addition, transcription factor FOXC2 also contributes to doxorubicin resistance through inducing the expression of the classical multi-drug resistance-related ABCB1 gene similar to FOXC2-AS1. Thus, we concluded that the lncRNA FOXC2-AS1 may promote doxorubicin resistance in OS by increasing the expression of transcription factor FOXC2, further facilitating ABCB1 expression. These findings demonstrate the potential underlying mechanism of FOXC2-AS1 in the regulation of doxorubicin resistance in OS and possibly provide a novel reversing target.

Update on Survival in Osteosarcoma

Osteosarcoma is the most common primary bone malignancy in children. Treatment has evolved to include systemic chemotherapy and local control surgery. Although survival improved initially in a drastic fashion with this approach, recent decades have seen little to no further gains in this area. Limb salvage surgery evolved with effective chemotherapy and advances in imaging, and continues to improve in the recent era. This article serves as a review of survival in high-grade osteosarcoma: prognostic factors, advances in chemotherapy and surgery, late effects of chemotherapy and surgery in survivors, and future directions.

Research advances in HMGN5 and cancer

High-mobility group nucleosome-binding domain 5 (HMGN5) is a new member of the high-mobility group N (HMGN) protein family that is involved in nucleosomal binding and transcriptional activation. It was first discovered in mouse, and recent studies found that the expressions of HMGN5 in many human cancers were also highly regulated, such as prostate, bladder, breast, and lung and clear cell renal cell carcinoma. Numerous reports have demonstrated that HMGN5 plays significant roles in many biological and pathological conditions, such as in developmental defects, hypersensitivity to stress, embryonic stem cell differentiation, and tumor progression. Importantly, deficiency of HMGN5 has been shown to be linked to cancer cell growth, cell cycle regulation, migration, invasion, and clinical outcomes, and it represents a promising therapeutic target for many malignant tumors. In the present review, we provide an overview of the current knowledge concerning the role of HMGN5 in cancer development and progression.

DNA strand breaks induced by nuclear hijacking of neuronal NOS as an anti-cancer effect of 2-methoxyestradiol

2-Methoxyestradiol (2-ME) is a physiological metabolite of 17β-estradiol. At pharmacological concentrations, 2-ME inhibits colon, breast and lung cancer in tumor models. Here we investigated the effect of physiologically relevant concentrations of 2-ME in osteosarcoma cell model. We demonstrated that 2-ME increased nuclear localization of neuronal nitric oxide synthase, resulting in nitro-oxidative DNA damage. This in turn caused cell cycle arrest and apoptosis in osteosarcoma cells. We suggest that 2-ME is a naturally occurring hormone with potential anti-cancer properties.