Osteosarcoma: basic science and clinical implications

Circ_0004674 regulation of glycolysis and proliferation mechanism of osteosarcoma through miR-140-3p/TCF4 pathway

As a subclass of noncoding RNAs, circular RNA play an important role in tumour development. The aim of this study was to investigate the role of circ_0004674 in osteosarcoma glycolysis and the molecular mechanism of its regulation. We examined the expression of circ_0004674, miR-140-3p, TCF4 and glycolysis-related proteins (including HK2, PKM2, GLUT1 and LDHA) in osteosarcoma cells and tissues by quantitative reverse transcription-polymerase chain reaction and immunoblotting (Western blot analysis). The role of circ_0004674, miR-140-3p and TCF4 in the proliferation, apoptosis, migration and invasion of OS cells was examined using CCK8 assay, Apoptosis assay, Wound healing assay, Transwell migration and Matrigel invasion assay. The interaction of circ_0004674/miR-140-3p and miR-1543/TCF4 was also analysed using a dual luciferase reporter assay. Finally, the glycolytic process was assessed by glucose uptake assays and lactate production measurements. The results showed that the expression of circ_0004674 and TCF4 was significantly higher in MG63 and U2OS cells compared to hFOB1.19 cells, while the expression of miR-140-3p was downregulated. Silencing of circ_0004674 gene significantly inhibited the proliferation, migration and invasion of cancer cells and promoted apoptosis of cancer cells. Experiments such as dual luciferase reporter analysis showed that circ_0004674 regulates the expression of glycolysis-related proteins through the miR-140-3p/TCF4 pathway, and inhibition of this gene attenuated the depletion of glucose content and the production of lactate in cancer cells. Furthermore, inhibition of miR-140-3p or overexpression of TCF could reverse the phenotypic changes in cancer cells induced by circ_0004674 silencing. In summary, this study elucidated the specific function and potential mechanisms of circ_0004674 in osteosarcoma glycolysis. The findings demonstrate that miR-140-3p and TCF4 function respectively as a tumor suppressor gene and an oncogene in osteosarcoma. Notably, they influence glycolysis and associated pathways, regulating osteosarcoma proliferation. Therefore, circ_0004674 promotes osteosarcoma glycolysis and proliferation through the miR-140-3p/TCF4 pathway, enhancing the malignant behaviour of tumours, and it is expected to be a potential molecular target for osteosarcoma treatment.

Distal Femur Cemented Modular Prosthesis Failure Causing a Medical Device-Related Adverse Event: A Report of a Rare Case

A distal femoral cemented modular prosthesis is a viable option for post-bone tumor and limb salvage procedures. The major reasons for implant failures are the poor quality of implants, mechanical stress, biochemical reactions, and extended period of the implant in vivo use. Rare incidences have been reported of distal femur prosthesis implant malfunctioning in a subject having osteosarcoma. Common adverse events associated with implant failure include surgical site infections, swelling, pain, revision of the surgical procedure, cyst formation, and build-up of metal debris on soft tissues. Our case report summarizes gross malfunctioning of a distal femur cemented modular prosthesis experienced by a 24-year-old post-operated osteosarcoma patient who developed excruciating sudden pain and the inability to bear weight on the right leg, with the sudden onset of these symptoms developing while turning in bed.

Osteosarcoma of the jaw: Primary versus secondary - A report of two cases

ABSTRACT

Osteosarcoma (OS) is the most common primary malignancy of bone excluding hematological malignancies. Most common sites of tumor are long bones of extremities. OS of the jaw are extremely rare with mandible being more commonly after than maxilla. Hereby, we present two cases of OS of jaw with one patient being male and other female.

The Multifaceted Therapeutic Mechanisms of Curcumin in Osteosarcoma: State-of-the-Art

Osteosarcoma is a major form of malignant bone tumor that typically occurs in young adults and children. The combination of aggressive surgical strategies and chemotherapy has led to improvements in survival time, although individuals with recurrent or metastatic conditions still have an extremely poor prognosis. This disappointing situation strongly indicates that testing novel, targeted therapeutic agents is imperative to prevent the progression of osteosarcoma and enhance patient survival time. Curcumin, a naturally occurring phenolic compound found in Curcuma longa, has been shown to have a wide variety of anti-tumor, anti-oxidant, and anti-inflammatory activities in many types of cancers including osteosarcoma. Curcumin is a highly pleiotropic molecule that can modulate intracellular signaling pathways to regulate cell proliferation, inflammation, and apoptosis. These signaling pathways include RANK/RANKL, Notch, Wnt/β-catenin, apoptosis, autophagy, JAK/STAT, and HIF-1 pathways. Additionally, curcumin can regulate the expression of various types of microRNAs that are involved in osteosarcoma. Therefore, curcumin may be a potential candidate for the prevention and treatment of osteosarcoma. This comprehensive review not only covers the use of curcumin in the treatment of osteosarcoma and its anti-cancer molecular mechanisms but also reveals the novel delivery strategies and combination therapies with the aim to improve the therapeutic effect of curcumin.

Anti-cancer properties of quercetin in osteosarcoma

Osteosarcoma is a primary bone tumor. Although it is a rare disease in general, it is the most common primary bone tumor among children. Despite the significant advances made in the field of osteosarcoma treatment, the outcomes of this disease are still unfavorable. Besides, there is still no targeted therapy for osteosarcoma that can be used in clinical settings. Quercetin is a member of the phytochemical family which is used for different diseases including cardiovascular diseases, diabetes, and cancer. Its anti-cancer effects are examined in many types of cancer including breast, colon, lung, prostate, and pancreatic cancers and have shown promising results. Herein, the studies dealing with the antitumor roles of quercetin in osteosarcoma are reviewed in this article. We take a look into quercetin's ability to affect proliferation, apoptosis, invasion, and chemo-resistance of the osteosarcoma cells through regulating protein expression and signaling pathways.

Research models and mesenchymal/epithelial plasticity of osteosarcoma

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

Chitosan applications in studying and managing osteosarcoma

Osteosarcoma has a high prevalence among children and adolescents. Common treatments of this disease are not promising enough. Molecular processes involved in the pathogenesis of osteosarcoma are not fully understood. Besides, the remnants of tumor cells after surgery can cause bone destruction and recurrence of the disease. Thus, there is a need to develop novel drugs or enhancing the currently-used drugs as well as identifying bone-repairing methods. Chitosan is a natural compound produced by the deacetylation of chitin. Research has shown that chitosan can be used in various fields due to its beneficial effects, such as biodegradability and biocompatibility. Regarding cancer, chitosan exerts several anti-tumor activities. Moreover, it can be used in diagnostic techniques, drug delivery systems, and cell culture methods. Herein, we aim to discuss the potential roles of chitosan in studying and treating osteosarcoma. We review the literature on chitosan's applications as a drug delivery system and how it can be combined with other substances to improve its ability of local drug delivery. We take a look into the studies concerning the possible benefits of chitosan in the field of bone tissue engineering and 3D culturing. Furthermore, anti-cancer activities of different compounds of chitosan are reviewed.

Construction of an integrated human osteosarcoma database, HOsDb, based on literature mining, microarray analysis, and database retrieval

Background

Osteosarcoma (OS) is the most frequent primary malignancy of bone with a high incidence in adolescence. This study aimed to construct a publicly available, integrated database of human OS, named HOsDb.

Methods

Microarray data, current databases, and a literature search of PubMed were used to extract information relevant to human OS-related genes and their transcription factors (TFs) and single nucleotide polymorphisms (SNPs), as well as methylation sites and microRNAs (miRNAs). This information was collated for constructing the HOsDb.

Results

In total, we identified 7191 OS tumor-related genes, 763 OS metastasis-related genes, and 1589 OS drug-related genes, corresponding to 190,362, 21,131, and 41,135 gene-TF pairs, respectively, 3,749,490, 358,361, and 767,674 gene-miRNA pairs, respectively; and 28,386, 2532, and 3943 SNPs, respectively. Additionally, 240 OS-related miRNAs, 1695 genes with copy number variations in OS, and 18 genes with methylation sites in OS were identified. These data were collated to construct the HOsDb, which is available at www.hosdatabase.com. Users can search OS-related molecules using this database.

Conclusion

The HOsDb provides a platform that is comprehensive, quick, and easily accessible, and it will enrich our current knowledge of OS.

Evodiamine Exerts Anticancer Effects Against 143B and MG63 Cells Through the Wnt/β-Catenin Signaling Pathway

Background

Osteosarcoma is the most common primary malignant bone neoplasm and is associated with abysmal prognosis. There are limitations of current treatment methods. Therefore, developing new agents to treat osteosarcoma is exceptionally urgent.

Aim

This study aimed to evaluate the anticancer effects of evodiamine (EVO) on osteosarcoma cells and, meanwhile, to investigate the underlying mechanisms involved.

Materials and Methods

The effect of EVO on the proliferation of osteosarcoma was detected by MTT assay, crystal violet assay and colony formation assay. The effects of EVO on the migration and invasion of osteosarcoma were detected by wound-healing assay and transwell assay. The effect of EVO on apoptosis of osteosarcoma was measured by Hoechst 33258 staining and cell cycle assay. 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 blotting assay.

Results

According to MTT, crystal violet and colony formation assay results, EVO significantly inhibited the cell proliferation in a dose-dependent manner. Hoechst 33258 staining assay revealed that EVO induced cell apoptosis in a concentration-dependent manner. Moreover, EVO inhibited the migration and invasion of the osteosarcoma cells. Mechanistic studies revealed that EVO suppresses metastatic through suppressing epithelial–mesenchymal transition (EMT) as indicated by elevating the expression of epithelial marker E‐cadherin and reducing the expression of mesenchymal markers N‐cadherin and vimentin, as well as EMT transcription factors Snail and MMPs. Subsequently, EVO induced cell cycle arrest at the G2/M phase that correlated with reduced levels of cyclin D1 protein, while the apoptotic effects of EVO were associated with the upregulation of Bax and Bad and a decrease in Bcl-2 protein levels. Furthermore, EVO exerted the anticancer effects by suppressing Wnt/β-catenin signal pathway in osteosarcoma cells.

Conclusion

In summary, EVO exhibited potent anticancer effects against human osteosarcoma cells and promoted apoptosis through suppressing Wnt/β-catenin signaling pathway. These results indicated that EVO may be regarded as a new approach for osteosarcoma treatment.

Antioxidant, Antiproliferative and Apoptosis-Inducing Efficacy of Fractions from Cassia fistula L. Leaves

: Cassia fistula L. is a highly admirable traditional medicinal plant used for the treatment of various diseases and disorders. The present study was performed to divulge the antioxidant, antiproliferative, and apoptosis-inducing efficacy of fractions from C. fistula leaves. The hexane (CaLH fraction), chloroform (CaLC fraction), ethyl acetate (CaLE fraction), n-butanol (CaLB fraction), and aqueous (CaLA fraction) were sequentially fractionated from 80% methanolic (CaLM extract) of C. fistula leaves. The CaLE fraction was fractionated using column chromatography to yield a pure compound, which was characterized as Epiafzelechin (CFL1) based on 1H, 13C, and DEPT135 NMR. Among these fractions, CaLE and isolated CFL1 fractions exhibited an effective antioxidant potential in Ferric ion reducing power, (2,2'-azino-bis (3-ethylbenzothiazoline -6-sulfonic acid)) cation radical scavenging, and nitric oxide radical scavenging assays. Epiafzelechin was investigated for its antiproliferative effects against MG-63 (osteosarcoma), IMR-32 (neuroblastoma), and PC-3 (prostate adenocarcinoma), and was found to inhibit cell proliferation with a GI50 value of 8.73, 9.15, and 11.8 μM respectively. MG-63 cells underwent apoptotic cell death on treatment with Epiafzelechin as the cells showed the formation of apoptotic bodies, enhanced reactive oxygen species (ROS) generation, mitochondrial membrane depolarization along with an increase in early apoptotic cell population analyzed using Annexin V-FITC/PI double staining assay. Cells showed cell cycle arrest at the G0/G1 phase accompanied by a downregulation in the expression levels of p-Akt (Protein kinase B), p-GSK-3β (Glycogen synthase kinase-3 beta), and Bcl-xl (B-cell lymphoma-extra large) proteins. RT-PCR (Real time-polymerase chain reaction) analysis revealed downregulation in the gene expression level of β-catenin and CDK2 (cyclin-dependent kinases-2) while it upregulated the expression level of caspase-8 and p53 genes in MG-63 cells.

lncRNA GAS8-AS1 downregulates lncRNA UCA1 to inhibit osteosarcoma cell migration and invasion

Background

Osteosarcoma (OS) is the most common type of primary bone tumor that mainly affects adolescents and young adults. The present study explored the role of lncRNA GAS8-AS1 in OS.

Methods

A total of 48 OS patients were selected from the 82 OS patients admitted by Luoyang Orthopedic Hospital of Henan Province between May 2010 and May 2013. Transient cell transfections, Transwell cell migration and invasion assay, RT-qPCR, and patient follow-up were carried out during the research.

Results

The results showed that GAS8-AS1 was downregulated, while UCA1 was upregulate in cancer tissues in comparison to adjacent non-cancer tissues of OS patients. GAS8-AS1 was not affected by clinical stage. Follow-up study showed that downregulated GAS8-AS1 in cancer tissues was closely correlated with poor survival. GAS8-AS1 and UCA1 were inversely correlated in cancer tissues. Overexpression of UCA1 failed to affect the expression of GAS8-AS1, while overexpression of GAS8-AS1 led to downregulated expression of UCA1 in OS cells, while the molecular mediators between these two lncRNAs are unknown. Overexpression of GAS8-AS1 did not affect OS cell proliferation but significantly inhibited cancer cell migration and invasion. Overexpression of UCA1 promoted the migration and invasion of OS cells and attenuated the effects of overexpressing GAS8-AS1.

Conclusions

Therefore, GAS8-AS1 may inhibit OS cell migration and invasion by downregulating oncogenic UCA1.

Silencing of RIPK4 inhibits epithelial‑mesenchymal transition by inactivating the Wnt/β‑catenin signaling pathway in osteosarcoma

Receptor interacting protein kinase 4 (RIPK4) is a serine/threonine kinase that plays an important role in the regulation of cell proliferation, invasion and metastasis in several malignancies; however, its clinical significance and biological function in osteosarcoma (OS) remains unknown. In the present study, the RIPK4 expression level was significantly upregulated in OS tissues and cell lines. High RIPK4 expression was positively associated with larger sized tumors, advanced Enneking stage and poor prognosis in patients with OS. Furthermore, the results revealed that RIPK4 knockdown in the OS cell lines MG‑63 and U2OS reduced cell migration and invasion via the inhibition of epithelial‑mesenchymal transition (EMT) process, whereby E‑cadherin expression was increased and N‑cadherin and vimentin expression decreased. Mechanistically, RIPK4 knockdown inhibited EMT by inactivating the Wnt/β‑catenin signaling pathway. These findings suggest that RIPK4 may be a novel potential therapeutic target for the treatment of metastases in patients with OS.

Radiographic manifestations of fibroblastic osteosarcoma: A diagnostic challenge

Osteosarcoma is the most common primary bone tumor after plasma cell neoplasms. Osteosarcoma has diverse histological features and is characterized by the presence of malignant spindle cells and pluripotent neoplastic mesenchymal cells that produce immature bone, cartilage, and fibrous tissue. Osteosarcoma most frequently develops in the extremities of long bones, but can occur in the jaw in rare cases. The clinical and biological behavior of osteosarcoma of the jaw slightly differs from that of long-bone osteosarcoma. The incidence of jaw osteosarcoma is greater in the third to fourth decades of life, whereas long-bone osteosarcoma mostly occurs in the second decade of life. Osteosarcoma of the jaw has a lower tendency to metastasize and a better prognosis than long-bone osteosarcoma. Radiographically, osteosarcoma can present as a poorly-defined lytic, sclerotic, or mixed-density lesion with periosteal bone reaction response. Multi-detector computed tomography is useful for identifying the extent of bone destruction, as well as soft tissue involvement of the lesion. The current case report presents a fibroblastic osteosarcoma involving the left hemimandible with very unusual radiographic features.

Capsaicin induces cytotoxicity in human osteosarcoma MG63 cells through TRPV1-dependent and -independent pathways

An accumulating body of evidence has shown that capsaicin induces apoptosis in various tumor cells as a mechanism of its anti-tumor activity. However, the effects of capsaicin on osteosarcoma have not been studied extensively. In the current study, we explore the molecular mechanism of capsaicin-mediated tumor suppressive function in osteosarcoma. We found that capsaicin-induced apoptosis and the activation of transient receptor potential receptor vanilloid 1 (TRPV1) in a dose- and time-dependent manner in human osteosarcoma MG63 cells in vitro. Blocking TRPV1 using capsazepine attenuated the capsaicin-induced cytotoxicity, mitochondrial dysfunction, overproduction of reactive oxygen species (ROS) and decrease in superoxide dismutase (SOD) activity. In addition, the results demonstrated that capsaicin induced the activation of adenosine 5'-monophosphate-activated protein kinase (AMPK), p53 and C-jun N-terminal kinase (JNK). In addition, Compound C (antagonist of AMPK) attenuated the activation of p53, which appeared to be TRPV1 independent. Taken together, the present study suggests that capsaicin effectively causes cell death in human osteosarcoma MG63 cells via the activation of TRPV1-dependent (mitochondrial dysfunction, and overproduction of ROS and JNK) and TRPV1-independent (AMPK-p53) pathways. Thus, capsaicin may be a potential anti-osteosarcoma agent.

Highly-expressed P2X7 receptor promotes growth and metastasis of human HOS/MNNG osteosarcoma cells via PI3K/Akt/GSK3β/β-catenin and mTOR/HIF1α/VEGF signaling

The P2X7 receptor, an ATP‐gated ion channel, is critical for cancer cell growth, invasiveness, and angiogenesis. Previous studies indicate that P2X7 regulates osteoblast proliferation and osteodeposition and that high P2X7 expression has a pro‐growth effect in osteosarcoma. However, how it functions in osteosarcoma cell growth and metastasis is not clear. Thus, we elucidated molecular mechanisms of P2X7‐dependent positive regulation of osteosarcoma cell proliferation, invasion, migration, epithelial to mesenchymal transition (EMT), and angiogenesis using in vitro and in vivo models. We confirm that P2X7 is highly‐expressed in human osteosarcoma tumor tissues and HOS/MNNG, MG63, U2OS, SW1353 and SAOS‐2 cell lines. P2X7 receptor stimulation enhanced HOS/MNNG and SAOS‐2 cell proliferation, migration and invasion; but knockdown of P2X7 expression or receptor inhibition had opposite effects. P2X7 positively regulated glycogen content, epithelial to mesenchymal transition and stemness of HOS/MNNG cells. P2X7 activation promoted PI3K/Akt/GSK3β/β‐catenin and mTOR/HIF1α/VEGF signaling, thereby mediating pro‐tumor effects of osteosarcoma cells. Consistent with data from in vitro experiments, systemic administration of P2X7 agonist induced tumor growth, metastasis and tumor‐associated bone destruction in osteosarcoma‐bearing nude mice, whereas a P2X7 antagonist reversed these effects. Thus, the P2X7 receptor participates in regulation of osteosarcoma growth and metastasis and we offer evidence that P2X7 may be a promising therapeutic target for treating osteosarcoma.

What's new?

The ATP‐gated ion channel receptor P2X7 is increasingly recognized as a tumor‐promoting factor. In this study, P2X7 was found to be overexpressed in human osteosarcoma tissues and cells, with its activation enhancing osteosarcoma cell proliferation, migration, and invasion. P2X7 activation further induced epithelial‐mesenchymal transition (EMT), affected the stemness of osteosarcoma cells, and augmented angiogenesis. Experiments in mice showed that P2X7 also induces osteosarcoma‐associated bone destruction. Opposing effects were observed upon P2X7 inhibition. P2X7 activity was influenced in part by PI3K/Akt/GSK3β/β‐catenin and mTOR/HIF1α/VEGF signaling pathways. The data identify P2X7 as a target for the development of novel therapeutics against osteosarcoma.

Osteosarcoma: a comprehensive review

Osteosarcoma (OS) is a relatively rare tumor of bone with a worldwide incidence of 3.4 cases per million people per year. For most of the twentieth century, five-year survival rates for classic OS were very low. In the 1970s, the introduction of adjuvant chemotherapy in the treatment of OS increased survival rates dramatically. The current article reviews the various types of OS and analyzes the clinical and histological features. We also examine historical and current literature to present a succinct review of methods for diagnosis and staging, as well as treatment, and we also discuss some of the future directions of treatment.

ATF4 regulated by MYC has an important function in anoikis resistance in human osteosarcoma cells

Anoikis resistance is a crucial step in the process of tumor metastasis. This step determines whether the tumor cells will survive when they become detached from the extracellular matrix. However, the specific mechanism of tumor cells to bypass anoikis and become resistant remains to be elucidated. The present study aimed to determine the internal mechanism of bypassing anoikis through comparison of human osteosarcoma cell lines with human normal cell lines. High activating transcription factor 4 (ATF4) and myelocytomatosis oncogene (MYC) expression levels were observed in MG-63 and U-2 OS human osteosarcoma cell lines. It is possible that ATF4 and MYC contribute to tumor progression. Subsequently, the expression levels of ATF4 and MYC in HUVEC and CHON-001 human normal cell lines were upregulated and their adhesion abilities were reduced; whereas their ability to bypass anoikis increased significantly. Simultaneously, after we Following a knock-down of ATF4 and MYC expression levels in MG-63 and U-2 OS human osteosarcoma cell lines, their adhesion ability increased and their ability to bypassing anoikis was significantly reduced. Upregulation of MYC resulted in an upregulation of ATF4, and chromatin immunoprecipitation and luciferase reporter gene technology demonstrated that MYC binds to the promoter of ATF4. These findings suggest that ATF4 regulated by MYC might contribute to resistance to anoikis in human osteosarcoma cells.

Tricetin inhibits human osteosarcoma cells metastasis by transcriptionally repressing MMP-9 via p38 and Akt pathways

Tricetin, a dietary flavonoid, has cytostatic properties and anti-metastasis activities in various cancer cells. However, the detailed impacts and underlying mechanisms of tricetin on human osteosarcoma cell metastasis are still unclear. Here, the hypothesis that tricetin possesses the anti-metastatic effects on human osteosarcoma cells was tested. The effects of tricetin on cell viability, motility, migration, and invasion in human osteosarcoma U2OS and HOS cells were investigated. Gelatin zymography, western blotting, polymerase chain reaction (PCR), and the luciferase assay were used to further explore the underlying mechanisms involved in anti-metastatic effects in U2OS cells. Their results showed that Tricetin, up to 80 μM without cytotoxicity, attenuated U2OS and HOS cells motility, invasiveness, and migration by reducing matrix metalloproteinase (MMP)-9 enzyme activities. In U2OS cells, tricetin decreased MMP-9 protein and mRNA expressions, which was confirmed by real-time PCR. Next, tricetin reduced phosphorylation of p38 and Akt, but no effect on phosphorylation of ERK1/2 and JNK. In conclusion, tricetin possesses the anti-metastatic activity of osteosarcoma cells by transcriptionally repressing MMP-9 via p38 and Akt signaling pathways. This may be potentially useful as anti-metastatic agents for osteosarcoma chemotherapy.

Correlation study of DNA methylation of WNT6 gene with osteosarcoma in children

The aim of this study was to evaluate the status and explore the impact of DNA methylation of WNT6 gene with osteosarcoma in children. A total of 50 patients with primary osteosarcoma in children were enrolled. The expression of WNT6 protein was determined by immunohistochemical staining. The DNA methylation level of WNT6 gene was evaluated by methylation-specific PCR (MSP). Human MG63 osteosarcoma cells and human normal Hfob1.19 osteoblasts were selected and cultured. Western blot analysis was utilized to measure the expression of WNT6 in the two cell lines. MSP was used to assess the status of DNA methylation of WNT6 gene. The correlation between DNA methylation of WNT6 gene and prognosis of osteosarcoma in children was evaluated by statistical analysis of the clinical and prognostic data. The results of the immunohistochemical assay showed that 84% (42/50) of primary osteosarcoma was WNT6 positive. MSP indicated that DNA methylation of WNT6 gene was found in 9 cases (18%) of primary osteosarcoma. Western blot analysis showed that WNT6 protein expression in MG63 cells was significantly higher than that in normal human Hfob1.19 osteoblasts, whereas, the level of DNA methylation of WNT6 gene in MG63 cells was significantly lower than in Hfob1.19 cells. Analysis of survival, prognosis and their correlation found that the DNA methylation level of WNT6 gene was negatively correlated with the prognosis of children with osteosarcoma. In conclusion, there was a high level of WNT6 gene expression in primary osteosarcoma, which was mainly due to low DNA methylation level of WNT6 gene. The DNA methylation of WNT6 gene was negatively correlated with the prognosis of patients with osteosarcoma in children.

2-Methoxyestradiol-Mediated Induction of Frzb Contributes to Cell Death and Autophagy in MG63 Osteosarcoma Cells

Osteosarcoma is a bone tumor that mainly affects children and adolescents. Although its pathogenesis is still not fully understood, activation of Wnt signaling has been implicated in the development and metastasis of osteosarcoma. In this report, we have investigated the effect of the anti-tumor compound, 2-methoxyestradiol (2-ME) on Wnt antagonist frizzled-related protein b (Frzb), also known as secreted frizzled-related protein (sFRP)3 in human osteosarcoma (MG63) cells. Our results show that 2-ME treatment induces Frzb gene promoter activity, and increases Frzb mRNA and protein levels in osteosarcoma cells. In addition, 2-ME treatment regulates downstream Wnt signaling, increasing the cytoplasmic levels of β-catenin, and blocking β-catenin-mediated Wnt activation in osteosarcoma cells. 2-ME-mediated induction of Frzb protein expression is specific to osteosarcoma cells, as it does not affect Frzb expression in normal primary human osteoblasts. Furthermore, 2-ME-induced apoptosis and autophagy are blocked in osteosarcoma cells transfected with Frzb siRNAs. Taken together, these studies demonstrate that Frzb protein plays an important role in 2-ME-mediated anti-tumor mechanisms in osteosarcoma cells. J. Cell. Biochem. 118: 1497-1504, 2017. © 2016 Wiley Periodicals, Inc.

Diagnostic accuracy of CD44V6 for osteosarcoma: a meta-analysis

Background

Recently, more and more evidences have revealed the association between CD44V6 and osteosarcoma (OS), but whether it can be used as a clinical biomarker is still unknown. The purpose of this study is to assess the diagnostic value of CD44V6 in OS by conducting a meta-analysis.

Methods

All relevant electronic literatures were collected from seven international databases together with three Chinese databases up to April 23, 2016. Eligible studies were selected through multiple search strategies and the quality was assessed by QUADAS. Data was extracted from studies according to the key statistics index. All analyses were performed using STATA 12 and Meta-DiSc 1.4 statistical software.

Results

According to the exclusion and inclusion criteria, 8 literatures were retrieved, accounting for 463 cases and 188 controls. For discriminating OS from benign bone tumor or healthy controls, the area under the receiver operating characteristic curve (AUC) was 0.91 (95 % CI 0.88–0.93). Overall, the results showed pooled sensitivity of 0.743 (95 % CI 0.606–0.844) and specificity of 0.897 (95 % CI 0.818–0.945), respectively. Substantial heterogeneity was detected in this study (I² = 90 %). The publication bias was assessed by using Deeks’ asymmetry test (p = 0.795). No evidence of heterogeneity from threshold effects was detected by the Spearman correlation coefficient (−0.506, p = 0.201). Meta-regression was performed to mining the source of heterogeneity, and subgroup analysis showed that neither the cut-off values nor the control groups were the source of heterogeneity.

Conclusions

The present results suggest that promoted CD44V6 expression levels are associated with OS and CD44V6 may be used as a diagnostic marker for OS.

Establishment of Cancer Stem Cell Cultures from Human Conventional Osteosarcoma

The current improvements in therapy against osteosarcoma (OS) have prolonged the lives of cancer patients, but the survival rate of five years remains poor when metastasis has occurred. The Cancer Stem Cell (CSC) theory holds that there is a subset of tumor cells within the tumor that have stem-like characteristics, including the capacity to maintain the tumor and to resist multidrug chemotherapy. Therefore, a better understanding of OS biology and pathogenesis is needed in order to advance the development of targeted therapies to eradicate this particular subset and to reduce morbidity and mortality among patients. Isolating CSCs, establishing cell cultures of CSCs, and studying their biology are important steps to improving our understanding of OS biology and pathogenesis. The establishment of human-derived OS-CSCs from biopsies of OS has been made possible using several methods, including the capacity to create 3-dimensional stem cell cultures under nonadherent conditions. Under these conditions, CSCs are able to create spherical floating colonies formed by daughter stem cells; these colonies are termed "cellular spheres". Here, we describe a method to establish CSC cultures from primary cell cultures of conventional OS obtained from OS biopsies. We clearly describe the several passages required to isolate and characterize CSCs.

3-Hydroxyflavone inhibits human osteosarcoma U2OS and 143B cells metastasis by affecting EMT and repressing u-PA/MMP-2 via FAK-Src to MEK/ERK and RhoA/MLC2 pathways and reduces 143B tumor growth in vivo

Many natural flavonoids have cytostatic and apoptotic properties; however, we little know whether the effect of synthetic 3-hydroxyflavone on metastasis and tumor growth of human osteosarcoma. Here, we tested the hypothesis that 3-hydroxyflavone suppresses human osteosarcoma cells metastasis and tumor growth. 3-hydroxyflavone, up to 50 μM without cytotoxicity, inhibited U2OS and 143B cells motility, invasiveness and migration by reducing matrix metalloproteinase (MMP)-2 and urokinase-type plasminogen activator (u-PA) and also impaired cell adhesion to gelatin. 3-hydroxyflavone significantly reduced p-focal adhesion kinase (FAK) Tyr397, p-FAK Tyr925, p-steroid receptor coactivator (Src), p-mitogen/extracellular signal-regulated kinase (MEK)1/2, p-myosin light chain (MLC)2 Ser19, epithelial cell adhesion molecule, Ras homolog gene family (Rho)A and fibronectin expressions. 3-hydroxyflavone also affected the epithelial-mesenchymal transition (EMT) by down-regulating expressions of Vimentin and α-catenin with activation of the transcription factor Slug. In nude mice xenograft model and tail vein injection model showed that 3-hydroxyflavone reduced 143B tumor growth and lung metastasis. 3-hydroxyflavone possesses the anti-metastatic activity of U2OS and 143B cells by affecting EMT and repressing u-PA/MMP-2 via FAK-Src to MEK/ERK and RhoA/MLC2 pathways and suppresses 143B tumor growth in vivo. This may lead to clinical trials of osteosarcoma chemotherapy to confirm the promising result in the future.

Establishment and Characterization of a Human Small Cell Osteosarcoma Cancer Stem Cell Line: A New Possible In Vitro Model for Discovering Small Cell Osteosarcoma Biology

Osteosarcoma (OSA) is the most common primary malignant bone tumor, usually arising in the long bones of children and young adults. There are different subtypes of OSA, among which we find the conventional OS (also called medullary or central osteosarcoma) which has a high grade of malignancy and an incidence of 80%. There are different subtypes of high grade OS like chondroblastic, fibroblastic, osteoblastic, telangiectatic, and the small cell osteosarcoma (SCO). In this study, for the first time, we have isolated, established, and characterized a cell line of cancer stem cells (CSCs) from a human SCO. First of all, we have established a primary finite cell line of SCO, from which we have isolated the CSCs by the sphere formation assay. We have proved their in vitro mesenchymal and embryonic stem phenotype. Additionally, we have showed their neoplastic phenotype, since the original tumor bulk is a high grade osteosarcoma. This research demonstrates the existence of CSCs also in human primary SCO and highlights the establishment of this particular stabilized cancer stem cell line. This will represent a first step into the study of the biology of these cells to discover new molecular targets molecules for new incisive therapeutic strategies against this highly aggressive OSA.

Curcumin and Osteosarcoma: Can Invertible Polymeric Micelles Help?

Systematic review of experimental and clinical data on the use of curcumin in the treatment of osteosarcoma is presented. The current status of curcumin's therapeutic potential against bone cancer is analyzed in regard to using polymeric micelles (including recently developed invertible, responsive, micelles) as a platform for curcumin delivery to treat osteosarcoma. The potential of micellar assemblies from responsive macromolecules in a controlled delivery of curcumin to osteosarcoma cells, and the release using a new inversion mechanism is revealed.

Combined over-expression of the hypoxia-inducible factor 2α gene and its long non-coding RNA predicts unfavorable prognosis of patients with osteosarcoma

BACKGROUND

LncRNA hypoxia-inducible factor-2α (HIF-2α) promoter upstream transcript (HIF2PUT) functions as a novel regulatory factor of osteosarcoma stem cells partly by controlling HIF-2α expression. The aim of this study was to investigate the clinical significance of HIF-2α and HIF2PUT in human osteosarcoma.

MATERIALS AND METHODS

Quantitative real-time PCR was performed to detect the expression levels of HIF-2α mRNA and HIF2PUT in 82 surgical specimens of primary osteosarcoma and matched non-cancerous bone tissues. Then, the associations of HIF-2α and/or HIF2PUT expression with various clinicopathological features of osteosarcoma patients were statistically analyzed. Moreover, their prognostic value was further evaluated.

RESULTS

Compared with non-cancerous bone tissues, HIF-2α mRNA and HIF2PUT expression were both significantly upregulated in osteosarcoma tissues (all P<0.001). Interestingly, the expression levels of HIF-2α mRNA in osteosarcoma tissues were positively correlated with those of HIF2PUT (r=0.28, P=0.009). Additionally, osteosarcoma patients with HIF-2α mRNA and/or HIF2PUT over-expression more frequently had large tumor size (all P<0.05), advanced clinical stage (all P<0.01) and positive distant metastasis (all P<0.01). Moreover, osteosarcoma patients with HIF-2α mRNA and/or HIF2PUT over-expression had a significantly shorter overall and disease-free survival (all P<0.05). Furthermore, Cox multivariate analysis identified that HIF-2α mRNA and/or HIF2PUT expression, clinical stage and distant metastasis were all independent and significant prognostic factors for both overall and disease-free survival (all P<0.05).

CONCLUSIONS

HIF-2α and HIF2PUT upregulation may be a common feature in human osteosarcomas with aggressive potency. The over-expression of the two molecules, alone or combined, may predict poor prognosis in osteosarcoma patients.

Anti-podoplanin Monoclonal Antibody LpMab-7 Detects Metastatic Lesions of Osteosarcoma

Osteosarcoma is the most common primary malignant bone tumor and is highly metastatic to the lungs. Therefore, the development of a novel molecular targeting therapy against metastasis of osteosarcoma is necessary. A platelet aggregation-inducing factor, podoplanin/aggrus, is involved in tumor metastasis. Furthermore, podoplanin expression was reported to be involved in the poor prognosis of osteosarcoma patients. However, the association between podoplanin expression and metastasis of osteosarcoma remains unclear because of the lack of highly sensitive anti-podoplanin monoclonal antibodies (MAbs). In this study, we used a novel anti-podoplanin MAb, LpMab-7, which is more sensitive than well-known anti-podoplanin MAbs in immunohistochemistry. Immunohistochemical analysis using LpMab-7 showed that podoplanin expression at primary lesions is observed in 15 out of 16 (93.8%) cases. Furthermore, podoplanin expression at metastatic lesions was higher compared with primary lesions in three out of four (75%) cases with lung metastasis. Because LpMab-7 has high sensitivity against podoplanin, it is expected to be useful for molecular targeting therapy for osteosarcomas.

The associations of vascular endothelial growth factor gene polymorphisms with susceptibility to osteosarcoma: evidence from a meta-analysis

Several studies have investigated the associations of the vascular endothelial growth factor (VEGF) gene polymorphisms with the susceptibility to osteosarcoma, while their conclusions are conflicting. This meta-analysis was performed to provide a comprehensive assessment on those associations. Electronic bibliographic databases were searched for potential studies focused on the relationship between VEGF polymorphisms and the susceptibility to osteosarcoma on 10 December 2015. Pooled odds ratios with 95% confidence intervals were conducted to assess the associations. After strict screening process, six articles consisted of 1220 osteosarcoma patients and 1576 controls were selected. The pooled results suggested that VEGF-2578C/A polymorphism was significantly associated with osteosarcoma risk in all genetic models as well as VEGF-634G/C polymorphism. When it came to VEGF+936C/T polymorphism, we detected significant associations under allele contrast, heterozygote, dominant and recessive models. As to VEFG-460T/C polymorphism, significant associations were demonstrated in allele contrast and heterozygote models. With regard to VEGF-1156G/A polymorphism, significant association was observed only in alleles contrast model. However, there was no significant association between VEGF-1612G/A polymorphism and risk of osteosarcoma. This meta-analysis suggests that these polymorphisms comprised of VEGF-2578C/A, VEGF-1156G/A, VEGF+936C/T, VEGF-634G/C and VEGF-460T/C are associated with osteosarcoma risk in Chinese Han population.

Reduced expression and prognostic implication of inhibitor of growth 4 in human osteosarcoma

Osteosarcoma is the most prevalent type of primary malignant bone tumor. Inhibitor of growth 4 (ING4) has been demonstrated to function as a tumor suppressor through multiple pathways, and is its expression is understood to be suppressed or reduced in various malignancies. The present study aimed to investigate the expression of ING4 and to determine its prognostic value in osteosarcoma tissue. Formalin-fixed, paraffin-embedded tissue microarrays were analyzed, and contained 41 osteosarcoma specimens and 11 normal bone tissue specimens with duplicate cores. ING4 expression was evaluated by immunohistochemical staining. The association between ING4 expression in the osteosarcoma and normal bone tissues was analyzed, in addition to the association between ING4 expression and Enneking classification of the osteosarcoma tissues. A significant statistical difference was observed in the ING4 immunohistochemical staining score between the osteosarcoma and normal bone tissues (P<0.001). Furthermore, a significant negative correlation was detected between the ING4 immunohistochemical staining scores and the Enneking classification results of the 41 osteosarcoma tissues (P=0.002). Low expression of ING4 was observed in the osteosarcoma specimens, and this reduced expression of ING4 was negatively correlated with Enneking classification. Thus, the results of the present study indicate that ING4 may serve as a promising prognostic marker in osteosarcoma.

Juxtacortical osteosarcoma of the mandible: Challenges in diagnosis and management

Parosteal osteosarcoma (OS) of the jaw is a rare type of OS with peculiar clinical radiographic and microscopic features. The aim of this article was to report and discuss a case of high-grade parosteal OS in the mandible of a 35-year-old woman. The patient reported sensing mild pain and swelling in the retro molar area on the left side of the mouth for a period of 4 years, despite continuous dental treatment. The radiographic evaluation showed a mixed radiopaque/radiolucent lesion in the body of the left side of the mandible. Destruction of the mandibular cortex in that area was also observed. After the initial histological study, the patient underwent partial hemi-mandibulectomy. Microscopic findings showed a tumor exhibiting spindle cells with nuclear hyperchromasia, moderate pleomorphism, and irregular osteoid formation, with chondroid differentiation noted with tumor-free margins. The immunohistochemical analysis showed the expression of negativity to p53, human epidermal growth factor receptor 2/neu, and positivity to S-100. The diagnosis was high-grade parosteal OS of the jaw. The 4 years clinical and imaging postoperative follow-up showed no evidence of recurrence. The literature on this unusual pathologic entity reviewed and diagnostic challenges described.

Invertible micellar polymer nanoassemblies target bone tumor cells but not normal osteoblast cells

Aim:

To demonstrate the capability of the invertible micellar polymer nanoassemblies (IMAs) to deliver and release curcumin using the recently discovered mechanism of macromolecular inversion to treat bone tumor cells.

Materials & Methods:

The effect of IMA-mediated delivery of curcumin on osteosarcoma cell survival was investigated using MTS assays. To assess the effect of IMAs-delivered curcumin on osteosarcoma cell growth, fluorescence-activated cell sorting was performed. The uptake of micellar nanoassemblies was followed using confocal microscopy.

Results & Discussion:

IMAs-delivered curcumin is effective in blocking osteosarcoma cell growth. It decreases cell viability in human osteosarcoma (MG63, KHOS, and LM7) cells while having no effect on normal human osteoblast cells. It indicates that curcumin-loaded IMAs provide a unique delivery system targeted to osteosarcoma cells.

Osteosarcoma is the most common primary bone malignancy that predominantly affects children and adolescents. Curcumin, a principal substance in the Asian spice turmeric, has been shown to block osteosarcoma cell growth. The clinical development of curcumin has been hindered due to poor aqueous solubility and thus, bioavailability, restricting its use as a drug. In this study, in order to improve the bioavailability and efficacy of curcumin, the drug was loaded (solubilized) into invertible micellar polymer nanoassemblies made from amphiphilic invertible polymers.

Targeted Chemotherapy in Bone and Soft-Tissue Sarcoma

Historically surgical intervention has been the mainstay of therapy for bone and soft-tissue sarcomas, augmented with adjuvant radiation for local control. Although cytotoxic chemotherapy revolutionized the treatment of many sarcomas, classic treatment regimens are fraught with side effects while outcomes have plateaued. However, since the approval of imatinib in 2002, research into targeted chemotherapy has increased exponentially. With targeted therapies comes the potential for decreased side effects and more potent, personalized treatment options. This article reviews the evolution of medical knowledge regarding sarcoma, the basic science of sarcomatogenesis, and the major targets and pathways now being studied.

Progression of Osteosarcoma from a Non-Metastatic to a Metastatic Phenotype Is Causally Associated with Activation of an Autocrine and Paracrine uPA Axis

Pulmonary metastasis is the major untreatable complication of osteosarcoma (OS) resulting in 10-20% long-term survival. The factors and pathways regulating these processes remain unclear, yet their identification is crucial in order to find new therapeutic targets. In this study we used a multi-omics approach to identify molecules in metastatic and non-metastatic OS cells that may contribute to OS metastasis, followed by validation in vitro and in vivo. We found elevated levels of the urokinase plasminogen activator (uPA) and of the uPA receptor (uPAR) exclusively in metastatic OS cells. uPA was secreted in soluble form and as part of the protein cargo of OS-secreted extracellular vesicles, including exosomes. In addition, in the tumour microenvironment, uPA was expressed and secreted by bone marrow cells (BMC), and OS- and BMC-derived uPA significantly and specifically stimulated migration of metastatic OS cells via uPA-dependent signaling pathways. Silencing of uPAR in metastatic OS cells abrogated the migratory response to uPA in vitro and decreased metastasis in vivo. Finally, a novel small-molecule inhibitor of uPA significantly (P = 0.0004) inhibited metastasis in an orthotopic mouse model of OS. Thus, we show for the first time that malignant conversion of OS cells to a metastatic phenotype is defined by activation of the uPA/uPAR axis in both an autocrine and paracrine fashion. Furthermore, metastasis is driven by changes in OS cells as well as in the microenvironment. Finally, our data show that pharmacological inhibition of the uPA/uPAR axis with a novel small-molecule inhibitor can prevent the emergence of metastatic foci.

CTGF increases matrix metalloproteinases expression and subsequently promotes tumor metastasis in human osteosarcoma through down-regulating miR-519d

Osteosarcoma, the most common primary malignant bone tumor, shows potent capacity for local invasion and distant metastasis. Connective tissue growth factor (CTGF/CCN2), a secreted protein, binds to integrins, modulates invasive behavior of certain human cancer cells. Effect of CTGF in metastasis of human osteosarcoma is unknown. We found overexpression of CTGF increasing matrix metalloproteinases (MMPs)-2 and MMP-3 expression as well as promoting cell migration. MicroRNA (miRNA) analysis of CTGF-overexpressed osteosarcoma versus control cells probed mechanisms of CTGF-mediated promotion of migration. Among miRNAs regulated by CTGF, miR-519d was most downregulated after CTGF treatment. Co-transfection with miR-519d mimic reversed CTGF-mediated MMPs expression and cell migration. Also, MEK and ERK inhibitors or mutants reduced CTGF-increased cell migration and miR-519d suppression. By contrast, knockdown of CTGF diminished lung metastasis in vivo. Clinical samples indicate CTGF expression as linked with clinical stage and tumor metastasis. Taken together, data show CTGF elevating MMPs expression and subsequently promoting tumor metastasis in human osteosarcoma, down-regulating miR-519d via MEK and ERK pathways, making CTGF a new molecular therapeutic target in osteosarcoma metastasis.

The prognostic significance of Src and p-Src expression in patients with osteosarcoma

Background

The expression of Src and phospho-Src (p-Src) is closely related to tumor invasion and metastasis. The aim of the present study was to investigate the expression of these molecules in osteosarcoma and their relationship with each other, to provide a theoretical basis to understand the prognosis of osteosarcoma.

Material/Methods

We selected surgically resected osteosarcoma specimens from 116 patients of Zhongnan Hospital of Wuhan University and Hubei Cancer Hospital, Hubei, China, between January 2000 and January 2010 with detailed follow-up data. Twenty osteochondroma specimens from the corresponding period were used as controls. Expression of Src and p-Src was detected in osteosarcoma and osteochondroma by immunohistochemistry. We analyzed the relationship of the 2 proteins and osteosarcoma patient prognosis.

Results

The expression of Src and p-Src in osteosarcoma was significantly higher than the expression level in osteochondroma (P<0.05). The expression levels of the 2 proteins, clinical stage, and tumor metastasis were significantly associated with survival time (P<0.05), but there was no correlation between age or sex and survival time. The expression of Src and p-Src in osteosarcoma was positively correlated.

Conclusions

Src and p-Src can be used as an auxiliary indicator to determine a malignant phenotype of bone tumors, and the combined detection of Src and p-Src may indicate the prognosis of osteosarcoma.

In vitro biosafety profile evaluation of multipotent mesenchymal stem cells derived from the bone marrow of sarcoma patients

Background

In osteosarcoma (OS) and most Ewing sarcoma (EWS) patients, the primary tumor originates in the bone. Although tumor resection surgery is commonly used to treat these diseases, it frequently leaves massive bone defects that are particularly difficult to be treated. Due to the therapeutic potential of mesenchymal stem cells (MSCs), OS and EWS patients could benefit from an autologous MSCs-based bone reconstruction. However, safety concerns regarding the in vitro expansion of bone marrow-derived MSCs have been raised. To investigate the possible oncogenic potential of MSCs from OS or EWS patients (MSC-SAR) after expansion, this study focused on a biosafety assessment of MSC-SAR obtained after short- and long-term cultivation compared with MSCs from healthy donors (MSC-CTRL).

Methods

We initially characterized the morphology, immunophenotype, and differentiation multipotency of isolated MSC-SAR. MSC-SAR and MSC-CTRL were subsequently expanded under identical culture conditions. Cells at the early (P3/P4) and late (P10) passages were collected for the in vitro analyses including: sequencing of genes frequently mutated in OS and EWS, evaluation of telomerase activity, assessment of the gene expression profile and activity of major cancer pathways, cytogenetic analysis on synchronous MSCs, and molecular karyotyping using a comparative genomic hybridization (CGH) array.

Results

MSC-SAR displayed comparable morphology, immunophenotype, proliferation rate, differentiation potential, and telomerase activity to MSC-CTRL. Both cell types displayed signs of senescence in the late stages of culture with no relevant changes in cancer gene expression. However, cytogenetic analysis detected chromosomal anomalies in the early and late stages of MSC-SAR and MSC-CTRL after culture.

Conclusions

Our results demonstrated that the in vitro expansion of MSCs does not influence or favor malignant transformation since MSC-SAR were not more prone than MSC-CTRL to deleterious changes during culture. However, the presence of chromosomal aberrations supports rigorous phenotypic, functional and genetic evaluation of the biosafety of MSCs, which is important for clinical applications.

Chick embryo extract demethylates tumor suppressor genes in osteosarcoma cells

BACKGROUND

Epigenetics is the study of changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence. It is widely accepted that cancer has genetic and epigenetic origins. The idea of epigenetic reprogramming of cancer cells by an embryonic microenvironment possesses potential interest from the prospect of both basic science and potential therapeutic strategies. Chick embryo extract (CEE) has been used for the successful expansion of many specific stem cells and has demonstrated the ability to facilitate DNA demethylation.

QUESTIONS/PURPOSES

The current study was conducted to compare the status of DNA methylation in highly metastatic and less metastatic osteosarcoma cells and to investigate whether CEE may affect the epigenetic regulation of tumor suppressor genes and thus change the metastatic phenotypes of highly metastatic osteosarcoma cells.

METHODS

K7M2 murine OS cells were treated with CEE to determine its potential effect on DNA methylation, cell apoptosis, and invasion capacity.

RESULTS

Our current results suggest that the methylation status of tumor suppressor genes (p16, p53, and E-cadherin) is significantly greater in highly metastatic mouse ostoesarcoma K7M2 cells in comparison with less metastatic mouse osteosarcoma K12 cells. CEE treatment of K7M2 cells caused demethylation of p16, p53, and E-cadherin genes, upregulated their expression, and resulted in the reversion of metastatic phenotypes in highly metastatic osteosarcoma cells.

CONCLUSIONS

CEE may promote the reversion of metastatic phenotypes of osteosarcoma cells and can be a helpful tool to study osteosarcoma tumor reversion by epigenetic reprogramming.

CLINICAL RELEVANCE

Demethylation of tumor suppressor genes in osteosarcoma may represent a novel strategy to diminish the metastatic potential of this neoplasm. Further studies, both in vitro and in vivo, are warranted to evaluate the clinical feasibility of this approach as an adjuvant to current therapy.

Impact of fibroblast activation protein on osteosarcoma cell lines in vitro

Fibroblast activation protein (FAP) or seprase, which belongs to the group type II integral serine proteases, is an integral membrane serine peptidase. Previous studies have demonstrated that FAP has an effect on tumor growth, proliferation and invasion. However, the cellular functional role that FAP plays in osteosarcoma (OS) remains unknown. The aim of the present study was to investigate the activities of FAP in OS cell lines. The gene expression of FAP was knocked down through a hammerhead ribozyme transgene, and the various functions between the knockdown cells and their control cells were tested using a series of functional assays in vitro. The results indicated that knockdown of FAP markedly reduced the ability of cellular growth, matrix adhesion, migration and invasion in MG-63 and HOS cell lines compared with the control cells (P<0.05). In conclusion, FAP influences OS cells and may play a role in OS tumor progression and metastasis.

Wnt signaling in osteosarcoma

Osteosarcoma (OS) is the most common primary bone malignancy diagnosed in children and adolescents with a high propensity for local invasion and distant metastasis. Despite current multidisciplinary treatments, there has not been a drastic change in overall prognosis within the last two decades. With current treatments, 60-70 % of patients with localized disease survive. Given a propensity of Wnt signaling to control multiple cellular processes, including proliferation, cell fate determination, and differentiation, it is a critical pathway in OS disease progression. At the same time, this pathway is extremely complex with vast arrays of cross-talk. Even though decades of research have linked the role of Wnt to tumorigenesis, there are still outstanding areas that remain poorly understood and even controversial. The canonical Wnt pathway functions to regulate the levels of the transcriptional co-activator β-catenin, which ultimately controls key developmental gene expressions. Given the central role of this mediator, inhibition of Wnt/β-catenin signaling has been investigated as a potential strategy for cancer control. In OS, several secreted protein families modulate the Wnt/β-catenin signaling, including secreted Frizzled-related proteins (sFRPs), Wnt inhibitory protein (WIF), Dickkopf proteins (DKK-1,2,3), sclerostin, and small molecules. This chapter focuses on our current understanding of Wnt/β-catenin signaling in OS, based on recent in vitro and in vivo data. Wnt activates noncanonical signaling pathways as well that are independent of β-catenin which will be discussed. In addition, stem cells and their association with Wnt/β-catenin are important factors to consider. Ultimately, the multiple canonical and noncanonical Wnt/β-catenin agonists and antagonists need to be further explored for potential targeted therapies.

Role of ezrin in osteosarcoma metastasis

The cause of death for the vast majority of cancer patients is the development of metastases at sites distant from that of the primary tumor. For most pediatric sarcoma patients such as those with osteosarcoma (OS), despite successful management of the primary tumor through multimodality approaches, the development of metastases, commonly to the lungs, is the cause of death. Significant improvements in long-term outcome for these patients have not been seen in more than 30 years. Furthermore, the long-term outcome for patients who present with metastatic disease is grave [1-5]. New treatment options are needed.Opportunities to improve outcomes for patients who present with metastases and those at-risk for progression and metastasis require an improved understanding of cancer progression and metastasis. With this goal in mind we and others have identified ezrin as a metastasis-associated protein that associated with OS and other cancers. Ezrin is the prototypical ERM (Ezrin/Radixin/Moesin) protein family member. ERMs function as linker proteins connecting the actin cytoskeleton and the plasma membrane. Since our initial identification of ezrin in pediatric sarcoma, an increasing understanding the role of ezrin in metastasis has emerged. Briefly, ezrin appears to allow metastatic cells to overcome a number of stresses experienced during the metastatic cascade, most notably the stress experienced as cells interact with the microenvironment of the secondary site. Cells must rapidly adapt to this environment in order to survive. Evidence now suggests a connection between ezrin expression and a variety of mechanisms linked to this important cellular adaptation including the ability of metastatic cells to initiate the translation of new proteins and to allow the efficient generation of ATP through a variety of sources. This understanding of the role of ezrin in the biology of metastasis is now sufficient to consider ezrin as an important therapeutic target in osteosarcoma patients. This chapter reviews our understanding of ezrin and the related ERM proteins in normal tissues and physiology, summarizes the expression of ezrin in human cancers and associations with clinical parameters of disease progression, reviews reports that detail a biological understanding of ezrin's role in metastatic progression, and concludes with a rationale that may be considered to target ezrin and ezrin biology in osteosarcoma.

High expression of MACC1 predicts poor prognosis in patients with osteosarcoma

Increasing evidence has demonstrated that high metastasis-associated in colon cancer-1 (MACC1) level is tightly associated with the development, progression, and poor prognosis of a variety of tumors. However, the relationship between MACC1 and the occurrence, development, and progression of osteosarcoma (OS) remains to be clarified. To facilitate and deepen the understanding of the associations of MACC1 with the development and progression of OS, in the current study, we detected the expressions of MACC1 mRNA and protein, and investigated the relationship between MACC1 expression and prognosis of the patients with OS. Our findings demonstrated that expressions of MACC1 mRNA and protein in OS tissues were significantly higher than those in paired normal bone tissues (P < 0.05). Additionally, the level of MACC1 mRNA in the patients with higher clinical stage and distant metastasis was markedly higher than those with lower clinical stage and without metastasis (P < 0.05). Furthermore, high MACC1 level was closely correlated with clinical stage and distant metastasis (P < 0.05), but not related to the patients' age, gender, tumor size, and anatomical location (P > 0.05). Stepwise investigation revealed that survival time of the patients with high MACC1 level was obviously lower than that with low MACC1 level (P < 0.05). Collectively, our data suggest that MACC1 may play important roles in the development and progression of OS, and thus may be considered as a novel molecular target for therapy of the patients with OS.

Notch Signaling is Associated with ALDH Activity and an Aggressive Metastatic Phenotype in Murine Osteosarcoma Cells

Osteosarcoma (OS) is the most common primary malignancy of bone, and pulmonary metastatic disease accounts for nearly all mortality. However, little is known about the biochemical signaling alterations that drive the progression of metastatic disease. Two murine OS cell populations, K7M2 and K12, are clonally related but differ significantly in their metastatic phenotypes and therefore represent excellent tools for studying metastatic OS molecular biology. K7M2 cells are highly metastatic, whereas K12 cells display limited metastatic potential. Here we report that the expression of Notch genes (Notch1, 2, 4) are up-regulated, including downstream targets Hes1 and Stat3, in the highly metastatic K7M2 cells compared to the less metastatic K12 cells, indicating that the Notch signaling pathway is more active in K7M2 cells. We have previously described that K7M2 cells exhibit higher levels of aldehyde dehydrogenase (ALDH) activity. Here we report that K7M2 cell ALDH activity is reduced with Notch inhibition, suggesting that ALDH activity may be regulated in part by the Notch pathway. Notch signaling is also associated with increased resistance to oxidative stress, migration, invasion, and VEGF expression in vitro. However, Notch inhibition did not significantly alter K7M2 cell proliferation. In conclusion, we provide evidence that Notch signaling is associated with ALDH activity and increased metastatic behavior in OS cells. Both Notch and ALDH are putative molecular targets for the treatment and prevention of OS metastasis.

Mesenchymal stem cells as delivery vehicle of porphyrin loaded nanoparticles: effective photoinduced in vitro killing of osteosarcoma

Mesenchymal stem cells (MSC) have the unique ability to home and engraft in tumor stroma. These features render them potentially a very useful tool as targeted delivery vehicles which can deliver therapeutic drugs to the tumor stroma. In the present study, we investigate whether fluorescent core-shell PMMA nanoparticles (FNPs) post-loaded with a photosensitizer, namely meso-tetrakis (4-sulfonatophenyl) porphyrin (TPPS) and uploaded by MSC could trigger osteosarcoma (OS) cell death in vitro upon specific photoactivation. In co-culture studies we demonstrate using laser confocal microscopy and time lapse imaging, that only after laser irradiation MSC loaded with photosensitizer-coated fluorescent NPs (TPPS@FNPs) undergo cell death and release reactive oxygen species (ROS) which are sufficient to trigger cell death of all OS cells in the culture. These results encourage further studies aimed at proving the efficacy of this novel tri-component system for PDT applications.

Reduced mitochondrial DNA copy number in Chinese patients with osteosarcoma

A plethora of somatic mutations and germline variations in mitochondrial DNA (mtDNA) have been increasingly reported in numerous cancer entities including osteosarcoma. However, it remains largely unclear whether mtDNA copy number changes occur during the multistep process of osteosarcoma carcinogenesis. For this purpose, we determined quantitative mtDNA levels in 31 primary osteosarcoma specimens and 5 normal bone tissue samples using a real-time polymerase chain reaction assay. Our data showed that the average mtDNA amount was significantly reduced in osteosarcoma tissues compared with normal bone controls. The copy number of mtDNA was statistically associated with tumor metastasis. There was an approximately 2-fold decrease of mtDNA quantity in tumors with metastasis than that in low-grade tumors without metastasis. Furthermore, change in mtDNA content was linked with somatic mutations in the D-loop regulatory region. Tumors carrying somatic D-loop mutations, at the polycytidine stretch between nucleotide positions 303 and 309 or close to the replication origin sites of the heavy strand, had significantly lowered mtDNA levels in comparison with those without mutations. Taken together, these results provide evidence for the first time that reduced mtDNA content may be critically implicated in the development and/or progression of osteosarcoma. Somatic D-loop mutation is likely one key factor among others leading to altered mtDNA amount in osteosarcoma.