Review of management issues in relapsed osteosarcoma

Metachronous Osteosarcoma, A Differential Diagnosis to be Considered in Children With Osteosarcoma: A Review of Literature and a Case From Our Center

Metachronous osteosarcomas (MOS) are currently defined as tumors that arise in a way and site unusual for typical metastasis. In this article, we reviewed the recent literature on the occurrence of metachronous osteosarcoma and presented a case from our center. Our patient, a 10-year-old girl, presented with metachronous osteoblastic osteosarcoma of the left distal femur ∼5 years after the successful treatment for osteosarcoma of the right distal femur. Even after several relapses, complete remission (CR) was achieved after the first osteosarcoma and after the metachronous osteosarcoma. The literature research revealed that metachronous osteosarcoma occurs in 3.4 to 5.4% of osteosarcoma patients. The time interval between the diagnosis of the initial osteosarcoma and the metachronous tumor ranged from 0.2 to 14.3 years (median 2.5 y). MOS appears to have differences in localization and metastatic spread, as well as a different survival pattern compared with primary osteosarcoma and osteosarcoma recurrence. Survival (median 4.3 y, range 0 to 24.6 y) appears to be associated with the time interval to diagnosis of MOS. In particular, early MOS (<24 mo after primary diagnosis) seem to have a poorer prognosis. Therefore, the occurrence of MOS at oncological unusual sites should be considered as a differential diagnosis in osteosarcoma survivors.

Prognostic factors and treatment of relapsed osteosarcoma: A monocentric Tunisian retrospective study

BACKGROUND

This study aimed to explore the treatment modalities of relapsed osteosarcoma, treatment results, and prognostic factors.

METHODS

We conducted a retrospective study of patients treated for relapsed osteosarcoma between 2005 and 2019. Patient survival was compared according to age, performance status, time to relapse, and surgical treatment at the relapse. Values of p<0.05 were considered to indicate statistical significance.

RESULTS

We included 49 patients who were treated for osteosarcoma. During the 13-year study period, 16 patients had relapsed osteosarcoma (32.7%). Prognostic factors of relapse were age over 18 years (p = 0.03), axial tumors (p = 0.01), and positive surgical margins (p = 0.018). Nine patients had palliative chemotherapy at the time of relapse. After a median follow-up of 8 months (range: 4-65 months), the overall survival at 1 year, 2 years, and 5 years after diagnosis of the relapse was 46.7%, 31.1%, and 20.7%, respectively. Relapsed osteosarcoma patients who had good performance status, late relapse (after 12 months), as well as surgery of the relapsed disease had better overall survival (OS).

CONCLUSION

Surgical treatment of relapsed osteosarcoma should be performed whenever possible since it improves significantly the survival of patients. Good performance status and late relapse were also associated with better survival.

Contribution of positron emission tomography/magnetic resonance imaging in musculoskeletal malignancies

Positron emission tomography/computed tomography (PET/CT) is a promising hybrid imaging technique for evaluating musculoskeletal malignancies. Both technologies, independently are useful for evaluating this type of tumors. PET/MR has great potential combining metabolic and functional imaging PET with soft tissue contrast and multiparametric sequences of MR. In this paper we review the existing literature and discuss the different protocols, new available radiotracers to conclude with the scarce evidence available the most useful/probable indications of the PET MR for the for musculoskeletal malignancies.

The increasing role of pigment epithelium-derived factor in metastasis: from biological importance to a promising target

Pigment epithelium-derived factor (PEDF) is a non-inhibitory member of the serpin (serine protease inhibitor) family and is a well-known potent anti-tumor factor in a variety of cancers. It has been ascertained that PEDF regulates multiple metastatic processes through various plausible mechanisms, including inhibiting angiogenesis, inducing apoptosis, stimulating extracellular matrix (ECM) degradation, and suppressing the epithelial-to-mesenchymal transition (EMT) process. Although PEDF has been recognized as an anti-metastatic marker in most studies, its role remains controversial with conflicting reports of PEDF as a metastatic marker. The emerging insights into the mechanism(s) of PEDF in tumor progression and its therapeutic effects are discussed systematically in this review, aiming to improve our understanding in the context of metastasis and drug development.

Receptor tyrosine kinase inhibitors for the treatment of osteosarcoma and Ewing sarcoma

Adjuvant chemotherapy for osteosarcoma and Ewing sarcoma consists of conventional cytotoxic regimens that have changed little over the past decades. There is an urgent need for agents that are more effective and have less long-term toxicity. Receptor tyrosine kinases regulate cell growth and proliferation of these tumors, and small-molecule inhibitors for many of these kinases are now available. In this article, we review published phase II trials for patients with recurrent disease and highlight the pathways targeted by available agents, as well as the toxicity and efficacy results seen to date. We also discuss the difficulties in identifying biomarkers to facilitate rational patient selection, as well as published and proposed strategies for how these inhibitors can be combined with conventional chemotherapy or other targeted agents. It is hoped future trials can capitalize on this growing experience to optimize the use of this exciting class of agents.

PIWI‑interacting RNA in cancer: Molecular mechanisms and possible clinical implications (Review)

PIWI‑interacting RNA is a class of non‑coding small RNA that is ~30 nt long and is primarily found in mammalian germ cells from mice and humans. In cooperation with the members of PIWI protein family, this macromolecule participates in germ cell development, inhibits DNA self‑-replication and maintains genomic stability. Increasing evidence has demonstrated that PIWI‑interacting RNA (piRNAs) are abnormally expressed in various human cancers, such as liver cancer, stomach cancer, colorectal cancer, osteosarcoma, breast cancer, lung cancer, prostate cancer, etc. piRNAs abnormal expression is also associated with the occurrence and development of human cancers, such as liver cancer, stomach cancer, colorectal cancer, etc. Despite their unclear molecular mechanisms, piRNAs may act as oncogenes or tumor suppressors by interacting with multiple cancer‑related signal pathways including STAT3/Bcl‑xl or coding genes, such as heat shock transcription factor‑1. Hence, piRNAs may be potential markers and targets and provide new opportunities for cancer diagnosis, treatment or prognosis monitoring. The current review mainly aims to highlight the latest research progress made in the biological functions and regulation of piRNAs in mammals, their involvement in various cancer forms and their potential clinical applications.

Double Endoprosthesis in the Management of Refractory Metastatic Primary Bone Tumors in Children and Young Adults

Background

Although not all children can be cured yet, much more emphasis is placed on the quality of life during and after cancer treatment. In the case of recurrence, mutilating treatment is still the prevalent option. In our study, we explored the role of limb salvage surgery for young patients with metastatic malignant bone tumors after endoprosthesis reconstruction during the first line of treatment and evaluated the impact of the local control modality in disease control and functional outcomes.

Materials and Methods

Eleven patients with bone tumor treated between 2007 and 2018 were included in this study. Both during primary treatment and during recurrence, limb salvage surgery was performed using a modular or expandable custom-made replacement system. Peri- and postoperative care for both surgeries were similar. All patients were given chemotherapy before and after both surgeries, according to the oncological guidelines.

Results

Seven patients (63.6%) are alive with a median follow-up of 6.5 years from diagnosis. None had local recurrence. Five-year estimates of event-free survival and overall survival were 36.27% and 79.55%, respectively. Median time between the first and second surgery was 2.7 years. Three patients presented with postoperative complications following both surgeries and required resurgical intervention. Three months following the second surgery, the Musculoskeletal Tumor Society Scale (MSTS) scores were 15–27 points (21 points on average—60%).

Conclusions

Limb salvage surgery is feasible and offers good chance of cure with a reasonable rate of complications and good function in patients with recurrent bone sarcoma after endoprosthesis reconstruction during the first line of treatment.

PRRX1 promotes malignant properties in human osteosarcoma

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PRRX1 is a poor-prognosis marker of human osteosarcoma.

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PRRX1 promotes proliferation, invasion, and drug resistance in human osteosarcoma.

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Forskolin was identified using RNA expression signatures of PRRX1 knockdown.

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Forskolin decreased proliferation and migration in human osteosarcoma.

Paired related homeobox 1 (PRRX1) is a marker of limb bud mesenchymal cells, and deficiency of p53 or Rb in Prrx1-positive cells induces osteosarcoma in several mouse models. However, the regulatory roles of PRRX1 in human osteosarcoma have not been defined. In this study, we performed PRRX1 immunostaining on 35 human osteosarcoma specimens to assess the correlation between PRRX1 level and overall survival. In patients with osteosarcoma, the expression level of PRRX1 positively correlated with poor prognosis or the ratio of lung metastasis. Additionally, we found PRRX1 expression on in 143B cells, a human osteosarcoma line with a high metastatic capacity. Downregulation of PRRX1 not only suppressed proliferation and invasion but also increased the sensitivity to cisplatin and doxorubicin. When 143B cells were subcutaneously transplanted into nude mice, PRRX1 knockdown decreased tumor sizes and rates of lung metastasis. Interestingly, forskolin, a chemical compound identified by Connectivity Map analysis using RNA expression signatures during PRRX1 knockdown, decreased tumor proliferation and cell migration to the same degree as PRRX1 knockdown. These results demonstrate that PRRX1 promotes tumor malignancy in human osteosarcoma.

LncRNA SNHG15 regulates osteosarcoma progression in vitro and in vivo via sponging miR-346 and regulating TRAF4 expression

Osteosarcoma (OS) is a common primary malignant bone tumor around the world. It has been reported that long noncoding RNAs (lncRNAs) take part in diverse pathological processes of OS; however, the mechanism remains unknown. This study aimed to uncover the profile of lncRNA small nucleolar RNA host gene 15 (SNHG15), its biological function, and its potential involvement in the mechanism of OS progression in vitro and in vivo. The expression of SNHG15 and TRAF4 was promoted in OS tissues opposite for that of miR-346. The silencing of SNHG15 limited the proliferation, invasion, and enhanced apoptosis of SaoS2 and HOS cells. Moreover, the putative binding sites between miR-346 and SNHG15 or TRAF4 were predicted by starBase and Targetscan software online, individually. Also, miR-346 deletion reversed the positive effects of SNHG15 elimination on proliferation, apoptosis, and invasion in cells. In addition, the upregulation of TRAF4 disrupted the biofunctional results from miR-346 promotion subsequently. Finally, SNHG15 knockdown repressed OS tumor growth in a xenograft tumor model. SNHG15 enhanced the progression of OS by regulating the miR-346/TRAF4 axis in vitro and in vivo.

The antimicrobial peptide tilapia piscidin 3 induces mitochondria-modulated intrinsic apoptosis of osteosarcoma cells

Osteosarcoma (OS) is the most common solid tumor of the bone that most often affects adolescents. The introduction of chemotherapy for the treatment of OS has largely improved the survival rates of patients with localized tumors. However, the 5-year survival rate of OS patients with relapsed or metastatic disease is only 10 to 20%. In this study, the antimicrobial peptide tilapia piscidin 3 (TP3), isolated from Nile tilapia (Oreochromis niloticus), was treated to OS MG63 cells. Our findings showed that TP3 concentration as low as 1 μM induced significant inhibition of cell viability and increased DNA fragmentation, as determined by the MTT and TUNEL assays, respectively. The protein expression levels of cleaved caspases 3/9 were increased. An in situ live-cell time-lapse video and cell tomographic microscopy images showed cellular blebbing, shrinkage, nuclear fragmentation, and chromatin condensation, with the formation of beaded apoptopodia. Moreover, there were significant increase in the production of TP3-induced mitochondrial and cellular reactive oxygen species (ROS), as well as down-regulated mitochondrial oxygen consumption and extracellular acidification rates. Additionally, TP3 enhanced mitochondrial fission, whereas fusion was attenuated. Furthermore, after administration of the mitochondria targeted antioxidant mitoTempo, TP3-induced ROS oxidant levels and alterations in cleaved caspases 3/9 expression were rescued. TP3 promoted mitochondria-modulated intrinsic apoptosis through the induction of ROS production, activation of caspases 3/9, and the down-regulation of mitochondrial oxygen consumption and extracellular acidification rates, suggesting that TP3 has potential as an innovative alternative for OS treatment.

SP1-Induced Upregulation of lncRNA LINC00514 Promotes Tumor Proliferation and Metastasis in Osteosarcoma by Regulating miR-708

Background

Growing studies have suggested the dysregulation of long non-coding RNAs (lncRNAs) in several tumors, including osteosarcoma (OS). However, limited studies report metastasis-associated lncRNAs in OS. Our present study aimed to explore the roles of lncRNA LINC00514 (LINC00514) in OS.

Materials and Methods

The LINC00514 expression was measured using qPCR assays in OS tissues and cell lines. The clinical significance of LINC00514 expression in OS patients was analyzed using chi-square test, Kaplan–Meier assays and multivariate analysis. The possible effects of LINC00514 in tumor cellular progression were determined using a series of functional assays. The mechanisms of LINC00514 action were explored through bioinformatics, luciferase reporter assays and RT-PCR assays. The mechanisms involved the upregulation of LINC00514 expression in OS were determined using luciferase reporter and chromatin immunoprecipitation (ChIP) assays.

Results

We showed that LINC00514 expressions were distinctly upregulated in both OS tissues and cell lines, especially in advanced cases. High levels of LINC0051 were positively correlated with advanced tumor stages, distant metastasis, and reduced survival of patients with OS. Functional experiments indicated that silencing of LINC00514 suppressed the ability of cell growth, colony formation and metastasis, whereas promoted cell apoptosis in vitro. Mechanistic investigation revealed that LINC00514 could directly bind to miR-708 and effectively serve as a ceRNA for miR-708. In addition, LINC00514 was upregulated by the transcription factor SP1.

Conclusion

Our findings revealed SP1-induced upregulation of LINC00514 as an oncogene in OS through competitively binding to miR-708, suggesting that there are potential diagnostic and treatment values of LINC00514 in OS.

Baicalein inhibits cell development, metastasis and EMT and induces apoptosis by regulating ERK signaling pathway in osteosarcoma

Background: Osteosarcoma is a highly malignant primary tumor. Baicalein has broad-spectrum anti-tumor effects. This study aimed to study the specific molecular regulatory mechanism of baicalein in anti-osteosarcoma and the possible regulatory signaling network involved.Methods: In vitro experiment, MG-63 cells treated with 0, 50, 75, and 100 μM of baicalein. Cell viability, proliferation, migration, invasion, cycle, apoptosis, and morphology were detected using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazoliumbromide (MTT), clone formation, wound healing, Transwell, flow cytometry, Hoechst staining, wound healing and microscopic observation. In addition, cycle, apoptosis and EMT-related proteins and p-ERK/ERK expression level were analyzed using western blotting. In vivo experiments were performed by BALB/c-nude mice model establishment to detect mice and tumor weight, tumor volume, positive rate and p-ERK/ERK expression when mice treated with 100 μM of baicalein.Results: Firstly, the IC₅₀ of baicalein was 67.57 μM. Then, baicalein decreased cell viability, proliferation, migration, invasion, and the expression of CDK2, Cyclin D1, Cyclin E1, Bcl-2, N-cad, Vimentin, MMP-2, MMP-9, p-ERK/ERK, while increased G1 phase numbers, apoptosis and the expression level of p21, p27, cleaved caspase 3/9, Bax, E-cad, ZO-1 in a dose-dependent manner in MG-63 cells. Also, baicalein reduced the body weight, tumor weight and volume and relative expression level of p-ERK/ERK in vivo.Conclusion: Baicalein inhibits cell development, metastasis, and EMT progress and induces cell cycle arrest and apoptosis by regulating ERK signaling pathway in osteosarcoma, and has a visible anti-osteosarcoma effect in vivo.

CCEPR is a novel clinical biomarker for prognosis and regulates cell proliferation through PCNA in osteosarcoma

CCEPR (cervical carcinoma expressed PCNA regulatory lncRNA) has been found to be upregulated and enhance cell proliferation in human cancers. However, the role of CCEPR in osteosarcoma remains to be discovered. In this study, we found CCEPR expression was elevated in osteosarcoma tissue specimens and cell lines compared with adjacent normal tissue specimens and osteoblast cell line, respectively. Meanwhile, osteosarcoma patients with advanced stage or tumor size greater than 8 cm had higher expression of CCEPR than patients with early stage or tumor size less than or equal to 8 cm, respectively. Survival analysis suggested that osteosarcoma patients with high CCEPR expression had a worse overall survival rate than those with low CCEPR expression. The in vitro study indicated that CCEPR positively regulated proliferating cell nuclear antigen (PCNA) expression in osteosarcoma cells and silencing of CCEPR inhibited osteosarcoma cell proliferation through decreasing PCNA expression. In conclusion, CCEPR is a potential prognostic predictor and functions as oncogenic long non-coding RNA (lncRNA) to regulate cell proliferation via PCNA in osteosarcoma.

Clinical case report of patients with osteosarcoma and anticancer benefit of calycosin against human osteosarcoma cells

Osteosarcoma (OS) is a malignant neoplasia in bone, characterized with main occurrence in teenagers. Calycosin (CC), a bioactive compound, is found to play potent pharmacological effects against cancer. Our previous study indicates CC-exerted benefits for anti-OS effect. However, further molecular mechanism behind this action needs to be investigated. In this study, human OS samples and clinical data were collected and used for further test and analysis. In addition, human osteosarcoma cell line (143B) and tumor-xenograft nude mice were used to evaluate antineoplastic activities of CC through a series of biochemical methods and immunoassays, respectively. Compared with non-OS controls, human OS samples showed increased levels of neoplastic microRNA-223 (miR-223), and elevated expressions of NF-κBp65, IκBα proteins in tumor cells. In cell culture study, CC-treated 143B cells showed reduced cell growth, increased lactic dehydrogenase (LD) content, and downregulated cellular miR-223 level. Immunolabeled cells of proliferating cell nuclear antigen, B-cell lymphoma 2 (Bcl-2), poly(ADP-ribose) polymerase (PARP) in CC treatments were decreased dose-dependently, while caspase-3 positive cells were elevated. Further, protein expressions of NF-κBp65, IκBα in CC-treated cells were downregulated. In addition, tumor-xenograft nude mice followed by CC treatments exhibited reductions of tumor mass, miR-223 levels, and Bcl-2, PARP-positive cells, as well as downregulations of NF-κBp65, IκBα protein expressions in OS samples. Taken together, these experimental findings reveal that CC exhibits potential pharmacological activities against OS through inducing apoptosis and inhibiting miR-223-IκBα signaling pathway in neoplastic cells.

Target therapy of TRIM-14 inhibits osteosarcoma aggressiveness through the nuclear factor-κB signaling pathway

Osteosarcoma is the most common cause of cancer-associated mortality and the prognosis is yet to be fully elucidated due to the paucity of effective therapeutic targets that significantly influence the quality of life and mean survival rates of patients with osteosarcoma. Studies have showed that tripartite motif-containing (TRIM)-14 is a member of the TRIM protein family that has a vital role in tumor progression and metastasis and promotes angiogenesis, invasion and apoptotic resistance of bone cancer. In this study, a chimeric antibody targeting TRIM-14 (Chanti-TRIM) was constructed and the molecular mechanism of target therapy for TRIM-14 was investigated in osteosarcoma cells and xenograft mice. The growth, migration and invasion properties of U-2OS cells were analyzed following incubation with 10–160 mg/ml Chanti-TRIM. Apoptosis of U-2OS cells was detected after Chanti-TRIM treatment. Matrix metalloproteinase (MMP)-9-mediated nuclear factor-κB (NF-κB) signal pathway was analyzed in U-2OS cells treated with Chanti-TRIM. The inhibitory efficacy of Chanti-TRIM was studied in U-2OS-bearing xenograft mice. Our results demonstrated that neutralizing TRIM-14 expression markedly inhibited the growth, migration and invasion of osteosarcoma cells, in vitro and in vivo. We found that TRIM-14 depletion decreased cell viability and induced cells apoptosis in vitro. In addition, we identified Chanti-TRIM inhibited growth and promoted apoptosis induced by cisplatin through MMP-9-mediated NF-κB signal pathway. Furthermore, we observed that Chanti-TRIM treatment inhibited osteosarcoma growth in vivo. Histological analysis indicated that apoptotic bodies were increased and NF-κB nuclear translocation factors, including Ikkβ, p65 and IkBα, were decreased in tumors treated by Chanti-TRIM. In conclusion, these results showed that Chanti-TRIM markedly inhibited the progression of osteosarcoma, suggesting Chanti-TRIM may be a potential anti-cancer agent that functions via the activation of the NF-κB pathway for osteosarcoma.

Baicalein inhibits progression of osteosarcoma cells through inactivation of the Wnt/β-catenin signaling pathway

Osteosarcoma is a very common type of malignant bone tumor in children and young adults and aberrant activation of Wnt/β-catenin signaling pathway has been discovered in osteosarcoma. The traditional Chinese medicine baicalein was proved to have anti-proliferative and anti-metastatic properties in osteosarcoma, but the mechanism remained poorly understood. In the present study, we assessed the effects of baicalein on osteosarcoma and detected the potential molecular mechanism. We found that baicalein significantly suppressed the proliferation of osteosarcoma cells in a concentration- and time-dependent manner. In additional, baicalein could induce apoptosis and cell cycle arrest and reduce cell motility. Moreover, the level of β-catenin and its target genes, including c-myc, cyclinD1, and survivin significantly decreased in baicalein-treated osteosarcoma cells, whereas exogenous expression of β-catenin could reverse the anti-proliferative and anti-metastatic effects of baicalein. Subsequently, we established a 143B xenograft tumor model and found that baicalein treatment significantly inhibited tumor growth accompanied with inhibiting Wnt/β-catenin pathway. Thus, these findings suggest that baicalein may be a potentially effective Chinese herbal medicine for therapeutics of osteosarcoma and Wnt/β-catenin signaling pathway may serve as an efficient molecular marker or predictive target for osteosarcoma.

Antisense lncRNA FOXF1-AS1 Promotes Migration and Invasion of Osteosarcoma Cells Through the FOXF1/MMP-2/-9 Pathway

Osteosarcoma (OS) is the most common primary malignant bone cancer in children and adolescents. Long non-coding RNAs (lncRNAs) have been shown to play significant role in various cancers, including OS. In a previous study, we have reported that a novel antisense lncRNA FOXF1-AS1, also known as FENDRR, could sensitize doxorubicin-resistance of OS cells through down-regulating ABCB1 and ABCC1. Here in, the critical role of FOXF1-AS1 in regulating OS progression was further investigated. Firstly, we found that FOXF1-AS1 and its antisense transcript FOXF1 expression were positively up-regulated in OS tissues and cell lines and correlated with poor prognosis of OS patients. Besides, FOXF1-AS1 as well as FOXF1 silencing significantly inhibited cell proliferation, migration, invasion of OS cells and tumor growth both in vitro and vivo through decreasing the expression of MMP2 and MMP9, whereas enhanced expression of FOXF1-AS1 had the opposite effects. In addition, mechanistically, both of FOXF1-AS1 and FOXF1 could regulate the expression of MMP2 and MMP9 at mRNA and protein levels, whereas FOXF1-AS1 could influence the FOXF1expression but FOXF1 did not have the same effect on FOXF1-AS1. Rescue assay further showed that FOXF1-AS1 overexpression efficiently reversed the knockdown of MMP2 and MMP9 expression induced by si-FOXF1. Thus, we concluded that FOXF1-AS1 may promote migration and invasion of OS cells through the FOXF1/MMP-2/-9 pathway. Taken together, these findings demonstrated the underlying mechanism of FOXF1-AS1 in the regulation of OS progression and provide a novel potential target in the OS therapy.

TRAF4 enhances osteosarcoma cell proliferation and invasion by Akt signaling pathway

TRAF4, or tumor necrosis factor receptor-associated factor 4, is overexpressed in several cancers, suggesting a specific role in cancer progression. However, its functions in osteosarcoma are unclear. This study aimed to explore the expression of TRAF4 in osteosarcoma tissues and cells, the correlation of TRAF4 to clinical pathology of osteosarcoma, as well as the role and mechanism of TRAF4 in osteosarcoma metastasis. The protein expression levels of TRAF4 in osteosarcoma tissues and three osteosarcoma cell lines, MG-63, HOS, and U2OS, were assessed. Constructed TRAF4 overexpression vectors and established TRAF4 overexpression of the U2OS cell line. Cell proliferation, cell invasion, protein levels, and TRAF4 phosphorylations were assessed following TRAF4 transfection, as well as the effects of TRAF4 siRNA on cell proliferation and invasion. The results show that TRAF4 protein levels in osteosarcoma tissues were significantly higher than that in normal bone tissues. Importantly, an obvious upregulation of TRAF4 was found in carcinoma tissues from patients with lung metastasis compared with patients without lung metastasis. Consistently, a similar increase in TRAF4 mRNA and protein was also demonstrated in the osteosarcoma cell lines MG-63, HOS, and U2OS compared to normal bone cells, hFOB1.19. When TRAF4 was overexpressed in U2OS cells, cell proliferation was significantly enhanced, accompanied by an increase in Ki67 expression and colony formation. Compared with the control and vector-treated groups, TRAF4 transfection increased the invasion potential of U2OS cells (p < 0.05). Interestingly, TRAF4 transfection significantly enhanced the phosphorylation of Akt. After blocking Akt with its specific siRNA, TRAF4-induced cell proliferation and invasion were dramatically attenuated. In summary, our findings demonstrated that TRAF4 enhances osteosarcoma cell proliferation and invasion partially by the Akt pathway. This work suggests that TRAF4 might be an important target in osteosarcoma.

Associations of chemo- and radio-resistant phenotypes with the gap junction, adhesion and extracellular matrix in a three-dimensional culture model of soft sarcoma

Background

Three-dimensional (3D) culture models are considered to recapitulate the cell microenvironment in solid tumors, including the extracellular matrix (ECM), cell-cell interactions, and signal transduction. These functions are highly correlated with cellular behaviors and contribute to resistances against chemo- and radio-therapies. However, the biochemical effects and mechanisms remain unknown in soft sarcoma. Therefore, we developed an in vitro 3D model of sarcoma to analyze the reasons of the chemo- and radio-resistance in therapies.

Methods

Four soft sarcoma cell lines, HT1080, RD, SW872, and human osteosarcoma cell line 1 (HOSS1), a cell line established from a patient-derived xenograft, were applied to 3D culture and treated with growth factors in methylcellulose-containing medium. Spheroids were examined morphologically and by western blotting, RT-qPCR, and immunofluorescence staining to analyze cell adhesion, gap junctions, ECM genes, and related factors. Proliferation and colony formation assays were performed to assess chemo- and radio-resistances between 3D and two-dimensional (2D) cell cultures. Annexin V and Propidium Iodide staining was used to detect early apoptotic sarcoma cells treated with Doxorubicin, Gemcitabine, and Docetaxel in the 3D model.

Results

The four soft sarcoma cell lines formed spheres in vitro by culture in modified condition medium. Compared with 2D cell culture, expression of ECM genes and proteins, including COL1A1, LOX, SED1, FN1, and LAMA4, was significantly increased in 3D culture. Analysis of cadherin and gap junction molecules showed significant changes in the gene and protein expression profiles under 3D conditions. These changes affected cell–cell communication and were mainly associated with biological processes such as cell proliferation and apoptosis related to chemo- and radio-resistances.

Conclusions

Our findings revealed significant differences between 3D and 2D cell culture systems, and indicated that cellular responsiveness to external stress such as radiation and chemotherapeutics is influenced by differential expression of genes and proteins involved in regulation of the ECM, cell adhesion, and gap junction signaling.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0175-0) contains supplementary material, which is available to authorized users.

Popliteal lymph node metastasis of tibial osteoblastic osteosarcoma

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Lymph node metastasis of osteosarcoma, which is a rare entity.

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Metastatic patterns could not be clearly explained.

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The effects of lymph node metastasis on prognosis are also not clearly defined and further studies are needed.

INTRODUCTION

We report a case with lymph node metastasis of osteosarcoma, which is a rare entity in comparison to hematogeneous lung or bone metastasis.

PRESENTATION OF CASE

Twenty-seven years old male patient referred to our clinic complaining of ongoing left knee pain and swelling since one month without a history of prior trauma. Magnetic resonance imaging (MRI) revealed a mass of malignant nature which causes more prominent expansion and destruction of the bone distally with periosteal reaction. A lymphadenomegaly 16 mm × 13 mm in diameter was also present in the popliteal fossa having the same signal pattern with the primary lesion. Thirteen weeks following the first referral of the patient, wide resection and reconstruction with modular tumor prosthesis was performed. Popliteal lymph node was excised through the same incision. Pathologic examination of the resected speciman reported osteoblastic osteosarcoma. The lymph node extirpated from the popliteal fossa was reported to be a metastasis of the primary tumor.

DISCUSSION

Osteosarcoma of the long bones is the most common primary malignant bone neoplasm of both childhood and adulthood. Osteosarcomas commonly metastasize hematogeneously to the lungs and bones. Lymph node metastasis is a rare entity. Similar studies report rates between 2.3% and 4%. It is not clearly explained, how lymph node metastasis in osteosarcoma occurs despite lack of lymphatic drainage in normal cortical and spongious bone.

CONCLUSION

Lymph node metastasis of osteosarcoma is a rare entity and metastatic patterns could not be clearly explained. On the other hand, the effects of lymph node metastasis on prognosis are also not clearly defined and further studies are needed.