Current questions in bone sarcomas

Extracellular Regucalcin: A Potent Suppressor in the Cancer Cell Microenvironment

The regucalcin gene is located on the X chromosome, comprising seven exons and six introns. This gene and protein are expressed in various tissues and cells and is predominantly expressed in human liver, kidney, and adrenal tissues. Regucalcin gene expression is enhanced via a mechanism mediated by several signaling molecules and transcription factors. Regucalcin plays a multifunctional role in cellular regulation in maintaining cell homeostasis. In addition, regucalcin has been implicated in several metabolic disorders and diseases. In particular, regucalcin plays a role as a novel suppressor in several types of cancer patients. Increased expression of regucalcin suppresses the growth of human cancer cells, suggesting its pivotal role in suppressing tumor development. The survival time of cancer patients is prolonged with increased expression of regucalcin in the tumor tissues. The adhesion, migration, invasion, and bone metastatic activity of cancer cells are blocked by the overexpression of regucalcin, promoting dormancy in cancer patients. Interestingly, regucalcin is also found in human serum, suggesting its character as a novel biomarker in various diseases. This extracellular regucalcin has been shown to suppress human cancer cells' growth and bone metastatic activity. Thus, extracellular regucalcin may play a vital role as a suppressor of human cancer activity. Alteration of the serum regucalcin levels in physiological and pathophysiological conditions may influence the activity of cancer cells in the microenvironment. This review will discuss the potential role of extracellular regucalcin in cancer cell activity as a critical suppressor in the cancer microenvironment.

Electrolyte prognosis scoring system can predict overall survival in patients with osteosarcoma

Osteosarcoma stands as the most prevalent bone tumor, characterized by a heightened tendency for local recurrence and distant metastasis, resulting in a bleak prognosis. Presently, there exists a shortage of novel markers to effectively determine the prognosis of osteosarcoma patients. Recent research indicates that hematological markers partially mirror an individual's microenvironment, offering potential insights into predicting patient prognosis. However, prior studies predominantly focused on the prognostic significance of singular hematological indices, failing to comprehensively represent the tumor microenvironment of patients. In our investigation, we meticulously gathered data on 22 hematological and electrolyte markers, utilizing LASSO Cox regression analysis to devise an Electrolyte Prognostic Scoring System (EPSS). The EPSS encompasses various indicators, including immunity, inflammation, coagulation, and electrolyte levels. Our findings indicate that the EPSS stands as an independent prognostic factor for overall survival among osteosarcoma patients. It serves as a valuable addition to clinical characteristics, adept at discerning high-risk patients from those deemed clinically low-risk. Furthermore, EPSS-based nomograms demonstrate commendable predictive capabilities.

9-O-monoethyl succinate berberine effectively blocks the PI3K/AKT signaling pathway by targeting Wnt5a protein in inhibiting osteosarcoma growth

BACKGROUND

Osteosarcoma (OS) is the most common primary bone malignancy, mainly affecting children, adolescents, and young adults, followed by the elderly, with a high propensity for local invasion and metastasis. Although surgery combined with chemotherapy has greatly improved the prognosis of patients with OS, the prognosis for metastatic or recurrent OS is still unsatisfactory. The research community has struggled to develop an effective chemotherapy treatment regimen for this tumor. For the creation of an OS drug, our research team has effectively developed and manufactured a new drug named 9-O-monoethyl succinate berberine (B2).

PURPOSE

In this study, we aimed to investigate the roles and functions of B2 in the treatment of OS.

METHODS

Human OS cell lines and mouse OS cell lines were used in vitro cell experiments, while BALB/c mice and BALB/c nude mice were used in vivo animal experiments. To investigate the molecular mechanism of B2 treatment, antibody microarray analysis, proteomic analysis, quantitative real-time PCR, immunohistochemical labeling, and western blotting analysis were mostly carried out. We assessed the impact of B2 on OS therapy and the underlying molecular pathways based on in vivo and in vitro studies.

RESULTS

Our findings demonstrated that B2 has the ability to inhibit the proliferation, migration, and invasion of OS cell lines, while also induce apoptosis in vitro. Additionally, our results suggested that B2 could effectively impede the growth of OS and has less heart and lung damage than cisplatin in vivo. In terms of mechanism, we discovered that the Wnt5a protein is significantly expressed in OS cell lines. Knockdown of Wnt5a can restrict OS cell lines proliferation, and overexpression of Wnt5a had the opposite results. B2 also had a strong affinity with Wnt5a and can inhibit the PI3K/AKT signaling pathway by targeting Wnt5a. Tumor cells proliferation can be inhibited by blocking the PI3K/AKT signaling pathway, and Wnt5a-mediated inactivation of the PI3K/AKT signaling pathway after B2 treatment. In vitro and in vivo experiments with Wnt5a overexpression, B2 significantly inhibited tumor growth, migration, and invasion. Moreover, B2 and Wnt5a also have a strong structural binding ability (binding energy of -7.567 ± 0.084 kcal/mol, binding values of 2.860 ± 0.434 µM), and three hydrogen bonds are generated at the docking positions of amino acids GLN286, ASN288, and ASN292.

CONCLUSION

In summary, our study confirmed for the first time that the growth of OS is related to abnormal overexpression of Wnt5a protein, and designed a novel small molecule inhibitor named B2 targeting Wnt5a protein, which inhibits OS growth by mediating PI3K/AKT signaling pathway by targeting Wnt5a protein. Our research laid the groundwork for the promotion of B2 as a new anticancer drug and revealed an innovative chemotherapeutic strategy for OS therapy.

Inhibitors of APE1 redox and ATM synergistically sensitize osteosarcoma cells to ionizing radiation by inducing ferroptosis

The resistance of osteosarcoma (OS) to ionizing radiation (IR) is an obstacle for effective patient treatment. Apurinic/apyrimidinic endonuclease-reduction/oxidation factor 1 (APE1/Ref-1) is a multifunctional protein with DNA repair and reduction/oxidation (redox) activities. We previously revealed the role of APE1 in OS radioresistance; however, whether the redox activity of APE1 is involved in OS radioresistance is unclear. APE1 regulates the activation of ataxia-telangiectasia mutated (ATM), an initiator of DNA damage response that mediates radioresistance in other cancers. The role of APE1 redox activity and ATM activation in OS radioresistance is unknown. Our study revealed that IR increased APE1 expression and ATM activation in OS cells, and APE1 directly regulated ATM activation by its redox activity. The combined use of an APE1 redox inhibitor and ATM inhibitor effectively sensitized OS cells to IR in vitro and in vivo. Mechanistically, the increased radiosensitization of OS cells by the combined use of the two inhibitors was mediated by increased ferroptosis. Co-treatment with the two inhibitors significantly decreased expression of the common targeted transcription factor P53 compared with single inhibitor treatment. Collectively, APE1 redox activity, ATM activation and their crosstalk play important roles in the resistance of OS to irradiation. Synergetic inhibition of APE1 redox activity and ATM activation sensitized OS cells to IR by inducing ferroptosis, which provides a promising strategy for OS radiotherapy.

EphA2-specific microvesicles derived from tumor cells facilitate the targeted delivery of chemotherapeutic drugs for osteosarcoma therapy

Despite advances in surgery and chemotherapy, the survival of patients with osteosarcoma (OS) has not been fundamentally improved over the last two decades. Microvesicles (MVs) have a high cargo-loading capacity and are emerging as a promising drug delivery nanoplatform. The aim of this study was to develop MVs as specifically designed vehicles to enable OS-specific targeting and efficient treatment of OS. Herein, we designed and constructed a nanoplatform (YSA-SPION-MV/MTX) consisting of methotrexate (MTX)-loaded MVs coated with surface-carboxyl Fe3O4 superparamagnetic nanoparticles (SPIONs) conjugated with ephrin alpha 2 (EphA2)-targeted peptides (YSAYPDSVPMMS, YSA). YSA-SPION-MV/MTX showed an effective targeting effect on OS cells, which was depended on the binding of the YSA peptide to EphA2. In the orthotopic OS mouse model, YSA-SPION-MV/MTX effectively delivered drugs to tumor sites with specific targeting, resulting in superior anti-tumor activity compared to MTX or MV/MTX. And YSA-SPION-MV/MTX also reduced the side effects of high-dose MTX. Taken together, this strategy opens up a new avenue for OS therapy. And we expect this MV-based therapy to serve as a promising platform for the next generation of precision cancer nanomedicines.

Regucalcin Is a Potential Regulator in Human Cancer: Aiming to Expand into Cancer Therapy

Regucalcin, a calcium-binding protein lacking the EF-hand motif, was initially discovered in 1978. Its name is indicative of its function in calcium signaling regulation. The rgn gene encodes for regucalcin and is situated on the X chromosome in both humans and vertebrates. Regucalcin regulates pivotal enzymes involved in signal transduction and has an inhibitory function, which includes protein kinases, protein phosphatases, cysteinyl protease, nitric oxide dynthetase, aminoacyl-transfer ribonucleic acid (tRNA) synthetase, and protein synthesis. This cytoplasmic protein is transported to the nucleus where it regulates deoxyribonucleic acid and RNA synthesis as well as gene expression. Overexpression of regucalcin inhibits proliferation in both normal and cancer cells in vitro, independent of apoptosis. During liver regeneration in vivo, endogenous regucalcin suppresses cell growth when overexpressed. Regucalcin mRNA and protein expressions are significantly downregulated in tumor tissues of patients with various types of cancers. Patients exhibiting upregulated regucalcin in tumor tissue have shown prolonged survival. The decrease of regucalcin expression is linked to the advancement of cancer. Overexpression of regucalcin carries the potential for preventing and treating carcinogenesis. Additionally, extracellular regucalcin has displayed control over various types of human cancer cells. Regucalcin may hold a prominent role as a regulatory factor in cancer development. Supplying the regucalcin gene could prove to be a valuable asset in cancer treatment. The therapeutic value of regucalcin suggests its potential significance in treating cancer patients. This review delves into the most recent research on the regulatory role of regucalcin in human cancer development, providing a novel approach for treatment.

Lung and bone metastases patterns in limb osteosarcoma: Surgical treatment of primary site improves overall survival

Osteosarcoma (OS) is one of the most prevalent malignant bone tumors. The proportion of patients with limb OS was relatively high. Lung metastasis (LM) and bone metastasis are the first and second most common metastatic types of OS, respectively. A total of 270 new cases of LM, 55 new cases of bone metastases (BM), and 36 new cases of lung and BM were diagnosed in the surveillance, epidemiology and end results database from 2010 to 2019. Univariate and multivariate logistic regression analyses were used to identify the risk factors for lung and/or BM, and Cox regression analyses were performed to identify the prognostic factors for lung and/or BM. Kaplan-Meier curves and log-rank tests were used to analyze the overall survival of limb OS patients with lung and/or BM. Female sex, telangiectatic OS type, central OS type, T3 stage, N1 stage, BM, surgical treatments, radiotherapy and chemotherapy were significantly correlated with LM. T3 stage, LM, liver metastases, and radiotherapy significantly correlated with BM. The small cell OS type, T2 stage, T3 stage, N1 stage, liver metastases, and radiotherapy were significantly correlated with lung and BM. Among limb OS patients with LM, the mean survival months of older age, black race, N1 stage, BM, brain metastases, no surgery, and no chemotherapy were lower than those of the control group. In limb OS patients with LM and BM, the mean survival months in the no surgery group was lower than in the surgery group. T stage and radiotherapy significantly influence the occurrence of limb OS with lung and/or BM. Surgery at the primary site has been shown to be effective in improving the survival rate of patients with lung and/or BM.

Lung and bone metastases patterns in osteosarcoma: Chemotherapy improves overall survival

Osteosarcoma (OS) is a malignant tumor originating from the mesenchymal tissue. Simultaneous reports of lung and bone metastases (BM) in OS are rare in the literature. A total of 353 new cases of lung metastases (LM), 93 new cases of BM, and 59 new cases of LM and BM were diagnosed in the Surveillance, Epidemiology and End Results (SEER) database from 2010 to 2019. Univariate and multivariate logistic regression analyses were used to identify risk factors for LM and/or BM, and Cox regression analyses were performed to identify the prognostic factors for LM and/or BM. Kaplan-Meier (K-M) curves and log-rank tests were used to analyze the overall survival of patients with LM and/or BM. LM was diagnosed in 353 patients. Female sex, tumor size >100 mm, telangiectatic OS type, central OS type, N1 stage, other locations, BM, surgical treatments, radiotherapy and chemotherapy were significantly correlated with LM. 93 patients were diagnosed with BM. 25 to 59 years old, T1 stage, presence of LM, liver metastases, radiotherapy, and surgical treatments were significantly correlated with the BM. 59 patients were diagnosed with LM and BM. The chondroblastic OS type, small cell OS type, T1 stage, N1 stage, other locations, liver metastases, radiotherapy, and surgical treatments were significantly correlated with LM and BM. Metastases, radiotherapy, and surgery at the primary site were significantly associated with LM and/or BM. Chemotherapy at the primary site has been shown to be effective in improving the survival rate of LM and/or BM. Of the OS patients with LM, 61.47% died, and older age, BM, no surgery, and no chemotherapy were harmful to survival. 72.04% of OS patients with BM died, and N1 stage, no surgery, and no chemotherapy were harmful for survival. 69.49% of OS patients with LM and BM died, and older age and no chemotherapy were harmful for survival.

Hematological Prognostic Scoring System Can Predict Overall Survival and Can Indicate Response to Immunotherapy in Patients With Osteosarcoma

Osteosarcoma is the most common primary malignant bone tumor with a high metastatic potential. Nowadays, there is a lack of new markers to identify prognosis of osteosarcoma patients with response to medical treatment. Recent studies have shown that hematological markers can reflect to some extent the microenvironment of an individual with the potential to predict patient prognosis. However, most of the previous studies have studied the prognostic value of a single hematological index, and it is difficult to comprehensively reflect the tumor microenvironment of patients. Here, we comprehensively collected 16 hematological markers and constructed a hematological prognostic scoring system (HPSS) using LASSO cox regression analysis. HPSS contains many indicators such as immunity, inflammation, coagulation and nutrition. Our results suggest that HPSS is an independent prognostic factor for overall survival in osteosarcoma patients and is an optimal addition to clinical characteristics and well suited to further identify high-risk patients from clinically low-risk patients. HPSS-based nomograms have good predictive ability. Finally, HPSS also has some hints for immunotherapy response in osteosarcoma patients.

A Nutritional Metabolism Related Prognostic Scoring System for Patients With Newly Diagnosed Osteosarcoma

Osteosarcoma is a primary malignant bone tumor with high metastatic potential. To date, achieving long-term survival of osteosarcoma patients remains a difficult task. Metabolic reprogramming has emerged as a new hallmark of cancer. However, studies on the prognostic value of hematological markers related to nutritional and metabolism in cancer patients are limited and contradictory. In this retrospective study, we extensively collected 16 hematological markers related to nutritional and metabolism in 223 osteosarcoma patients. A nutritional metabolism related prognostic scoring system (NMRS) in patients with osteosarcoma was constructed by least absolute contraction and selection operator (LASSO) cox regression analysis. Compared with individual hematological indicators, NMRS has stronger predictive power (training set: 0.811 vs. 0.362–2.638; validation set: 0.767 vs. 0.333–0.595). It is an independent prognostic factor for the survival of patients with osteosarcoma [HR: 1.957 (1.375–2.786) training set; HR: 3.146 (1.574–6.266) validation set]. NMRS-based nomograms have good and stable predictive power. NMRS facilitates further risk stratification of patients with the same clinical characteristics.

Is Chemotherapy Associated with Improved Overall Survival in Patients with Dedifferentiated Chondrosarcoma? A SEER Database Analysis

BACKGROUND

Dedifferentiated chondrosarcoma is a chondrosarcoma subtype associated with high rates of recurrence and a poor prognosis. Others have proposed treatment of dedifferentiated chondrosarcoma using osteosarcoma protocols, including perioperative chemotherapy. However, the rarity of this condition poses difficulties in undertaking single- institution studies of sufficient sample size.

QUESTION/PURPOSE

Is perioperative chemotherapy associated with improved overall survival in patients with dedifferentiated chondrosarcoma?

METHODS

We queried the Surveillance, Epidemiology, and End Results (SEER) 1973 to 2016 database for patients with a diagnosis of dedifferentiated chondrosarcoma (n = 308). As dedifferentiated chondrosarcoma was only classified as a distinct entity in SEER starting in 2000, only patients treated in 2000 and later were included. We excluded from our analyses those patients with distant disease at diagnosis, a primary site of disease other than bone or joints, and those who did not receive cancer-directed surgery. These criteria yielded 185 dedifferentiated chondrosarcoma patients for inclusion. We used Kaplan-Meier analyses and Cox proportional hazards models to assess the association of clinical, demographic, and treatment characteristics on overall survival (OS).

RESULTS

After controlling for confounding variables, including age, sex, tumor size, stage, grade, location, and radiation treatment status, and after adjusting for missing data, no overall survival benefit was associated with receipt of chemotherapy in patients with dedifferentiated chondrosarcoma (hazard ratio 0.75 [95% confidence interval 0.49 to 1.12]; p = 0.16).

CONCLUSION

Chemotherapy treatment of dedifferentiated chondrosarcoma was not associated with improved OS. These results must be viewed cautiously, given the limited granularity of information on chemotherapy treatment, the concerns regarding chemotherapy misclassification in SEER data, and the small sample of patients with dedifferentiated chondrosarcoma, all of which limit the power to detect a difference. Our findings are nevertheless consistent with those of prior reports in which no benefit of chemotherapy could be detected. Lack of clear benefit from perioperative chemotherapy in dedifferentiated chondrosarcoma argues that it should be used only after careful consideration, and ideally in the context of a clinical trial.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Resource-appropriate selection of osteosarcoma treatment protocols in low- and middle-income countries

Osteosarcoma is a rare malignancy; however, it is still the most common primary bone tumor in adolescents and young adults. Chemotherapy improves survival indubitably in osteosarcoma; nevertheless, the concern is the stagnant progress since the last several decades. There are a handful of active agents and unresolved issues, especially in choosing the ideal chemotherapy regimen. The oncology community is in equipoise regarding the position of high-dose methotrexate (HDMTX), mandatory or adjunct. The choice of therapy becomes widely relevant, including in low- and middle-income countries (LMIC), where HDMTX administration brings additional complexities. Research into novel non-HDMTX-based protocols adapted to the available resources is pivotal in improving disease outcomes, especially in LMIC. The current review focuses on real-world challenges in decision-making and provides a comprehensive overview of the evolution of treatment protocols in LMIC.

ZIP10 drives osteosarcoma proliferation and chemoresistance through ITGA10-mediated activation of the PI3K/AKT pathway

Background

The zinc transporters Zrt- and Irt-related protein (ZIP/SLC39) are overexpressed in human tumors and correlate with poor prognosis; however, their contributions to carcinogenesis and chemoresistance in osteosarcoma (OS) remain unclear.

Methods

We collected 64 OS patient tissues with (n = 12) or without (n = 52) chemotherapy. The expression levels of ZIP10 were measured by immunohistochemistry and applied to prognostic analysis. ZIP10 was knocked down or overexpressed in OS cell lines to explore its effect on proliferation and chemoresistance. RNA sequencing, quantitative real-time PCR, and western blotting analysis were performed to explore ZIP10-regulated downstream target genes. A xenograft mouse model was established to evaluate the mechanisms by which ZIP10 modulates chemoresistance in OS cells.

Results

The expression of ZIP10 was significantly induced by chemotherapy and highly associated with the clinical outcomes of OS. Knockdown of ZIP10 suppressed OS cell proliferation and chemoresistance. In addition, ZIP10 promoted Zn content-induced cAMP-response element binding protein (CREB) phosphorylation and activation, which are required for integrin α10 (ITGA10) transcription and ITGA10-mediated PI3K/AKT pathway activation. Importantly, ITGA10 stimulated PI3K/AKT signaling but not the classical FAK or SRC pathway. Moreover, overexpression of ZIP10 promoted ITGA10 expression and conferred chemoresistance. Treatment with the CREB inhibitor 666–15 or the PI3K/AKT inhibitor GSK690693 impaired tumor chemoresistance in ZIP10-overexpressing cells. Finally, a xenograft mouse model established by subcutaneous injection of 143B cells confirmed that ZIP10 mediates chemotherapy resistance in OS cells via the ZIP10-ITGA10-PI3K/AKT axis.

Conclusions

We demonstrate that ZIP10 drives OS proliferation and chemoresistance through ITGA10-mediated activation of the PI3K/AKT pathway, which might serve as a target for OS treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02146-8.

Trends in Tumor Site-Specific Survival of Bone Sarcomas from 1980 to 2018: A Surveillance, Epidemiology and End Results-Based Study

OBJECTIVES

As diagnosis and treatment guidelines for bone sarcomas continue updating, it is important to examine whether, when, and which kinds of patients have had a survival improvement over the last four decades.

METHODS

This cohort study included 9178 patients with primary bone and joint sarcomas from 1 January 1980 to 31 December 2018 using data from Surveillance, Epidemiology and End Results (SEER)-9 Registries. The follow-up period was extended to November 2020. Patients were divided by decade into four time periods: 1980-1989, 1990-1999, 2000-2009, and 2010-2018. The primary endpoint was bone sarcomas-specific mortality (CSM). The 5-year bone sarcomas-specific survival (CSS) rate was determined stratified by demographic, neoplastic, temporal, economic, and geographic categories. The associations between time periods and CSM were examined using a multivariable Cox regression model, with reported hazard ratio (HR) and 95% confidence interval (CI).

RESULTS

The 5-year CSS rate for bone sarcomas was 58.7%, 69.9%, 71.0%, and 69.2%, in the 1980s, 1990s, 2000s, and 2010s, respectively. Older age, male gender, tumor sites at pelvic bones, sacrum, coccyx and associated joints, as well as vertebral column, osteosarcoma and Ewing tumor, and residence in non-metropolitan areas were independently associated with higher CSM risk. After adjusting for the covariates above, patients in the 1990s (HR = 0.74, 95% CI = 0.68-0.82), 2000s (HR = 0.71, 95% CI = 0.65-0.78), and 2010s (HR = 0.68, 95% CI = 0.62-0.76) had significantly lower CSM risks than patients in the 1980s. However, patients in the 2000s and 2010s did not have lower CSM risks than those in the 1990s (both p > 0.05).

CONCLUSIONS

Although bone sarcomas survival has significantly improved since 1990, it almost halted over the next three decades. Bone sarcomas survival should improve over time, similar to common cancers. New diagnostic and therapeutic strategies such as emerging immune and targeted agents are warranted to overcome this survival stalemate.

ICG-001, an Inhibitor of the β-Catenin and cAMP Response Element-Binding Protein Dependent Gene Transcription, Decreases Proliferation but Enhances Migration of Osteosarcoma Cells

High-grade osteosarcomas are the most frequent malignant bone tumors in the pediatric population, with 150 patients diagnosed every year in France. Osteosarcomas are associated with low survival rates for high risk patients (metastatic and relapsed diseases). Knowing that the canonical Wnt signaling pathway (Wnt/β-catenin) plays a complex but a key role in primary and metastatic development of osteosarcoma, the aim of this work was to analyze the effects of ICG-001, a CBP/β-catenin inhibitor blocking the β-catenin dependent gene transcription, in three human osteosarcoma cell lines (KHOS, MG63 and 143B). The cell proliferation and migration were first evaluated in vitro after ICG-001 treatment. Secondly, a mouse model of osteosarcoma was used to establish the in vivo biological effect of ICG-001 on osteosarcoma growth and metastatic dissemination. In vitro, ICG-001 treatment strongly inhibits osteosarcoma cell proliferation through a cell cycle blockade in the G0/G1 phase, but surprisingly, increases cell migration of the three cell lines. Moreover, ICG-001 does not modulate tumor growth in the osteosarcoma mouse model but, rather significantly increases the metastatic dissemination to lungs. Taken together, these results highlight, despite an anti-proliferative effect, a deleterious pro-migratory role of ICG-001 in osteosarcoma.

Inhibiting proliferation and metastasis of osteosarcoma cells by downregulation of long non-coding RNA colon cancer-associated transcript 2 targeting microRNA-143

Osteosarcoma is a malignant bone tumor, which has a high incidence in children and adolescents. However, the pathogenesis of osteosarcoma remains unclear. Long noncoding RNA (lncRNA) is a new potential therapeutic target and diagnostic biomarker for osteosarcoma. Hence, the present study aimed to explore the effect of lncRNA colon cancer-associated transcript (CCAT2) on osteosarcoma and its potential underlying mechanisms. For this purpose, the proliferation of osteosarcoma cells was measured using the CCK-8 assay. The scratch-wound and cell invasion assays were used to determine the migration and invasion of osteosarcoma cells, respectively. LncRNA CCAT2 and microRNA (miR)-143 binding sites were identified by the dual-luciferase reporter assay. RNA and protein expression levels were detected by reverse-transcription quantitative PCR and western blotting, respectively. Downregulation of lncRNA CCAT2 inhibited the proliferation, migration, and invasion of osteosarcoma cells. The findings also revealed that miR-143 bound directly to lncRNA CCAT2. The expression of miR-143 was upregulated by the knockdown of lncRNA CCAT2. Downregulation of the FOS-like antigen 2 was also observed after knockdown of lncRNA CCAT2. The function of lncRNA CCAT2 in osteosarcoma cells was attenuated by co-transfection with anti-miR-143 oligodeoxyribonucleotide. In conclusion, downregulation of lncRNA CCAT2 inhibited the proliferation and metastasis of osteosarcoma cells by targeting miR-143. lncRNA CCAT2 was identified as a potential target for osteosarcoma treatment.

The value of chest and skeletal staging studies in conventional chondrosarcoma

OBJECTIVE

To determine the value of chest and skeletal staging in patients presenting with conventional chondrosarcoma (CS).

MATERIALS AND METHODS

Retrospective review of patients with CS diagnosed between January 2007 and December 2019. Data collected included age, sex, skeletal location and results of chest CT and whole-body bone scintigraphy (WB-BSc) obtained at initial diagnosis. The histological tumour grade based on surgical resection or needle biopsy was classified as low-grade (LGCT), high-grade (HGCT) and dedifferentiated (DD-CS). Findings of chest CT and WB-BSc were correlated with tumour grade.

RESULTS

Four hundred twenty patients were included (234 males and 186 females with mean age 54.5 years, range 9-91 years). The major long bones were involved in 205 cases, the flat bones in 166 cases, the mobile spine in 14 cases and the small bones of the hands and feet in 35 cases. Three hundred fifty tumours were central in location, 39 peripheral and 31 on the surface of the bone. There were 151 LGCTs, 196 HGCTs and 73 DD-CSs. Of patients with LGCT, 41.7% underwent chest CT and 25.2% WB-BSc. Of patients with HGCT, 95.4% underwent chest CT and 76.5% WB-BSc. Of patients with DD-CS, 98.6% underwent chest CT and 86.3% WB-BSc. Metastases were diagnosed in 2 (3.3%) chest CT studies and 0 WB-BSc in LGCT, in 8 (4.3%) chest CT studies and 0 WB-BSc in HGCT and in 21 (30%) chest CT studies and 6 (21%) WB-BSc in DD-CS.

DISCUSSION

Staging chest CT and WB-BSc is of little or no value except in DD-CS.

PTEN in osteosarcoma: Recent advances and the therapeutic potential

Osteosarcoma is the most common primary malignant bone tumor, predominantly occurring in children and adolescents. Despite treated with surgery and neoadjuvant chemotherapy, osteosarcoma has a high potential of local recurrence and lung metastasis. Overall survival rates for osteosarcoma have plateaued in the past four decades, therefore, identification of novel targets and development of more effective treatment strategies are urgent. Phosphatase and tensin homolog (PTEN) is a tumor suppressor gene that negatively regulates the phosphatidylinositol 3-kinase (PI3K)/ protein kinase B (AKT)/ mammalian target of rapamycin (mTOR) pathway. Over half of clinical osteosarcoma samples presented loss or low expression of PTEN, which usually indicated an advanced stage of tumor and a poor prognosis. The expression of PTEN is regulated by epigenetic silence, transcription regulation, post-translational modifications, and protein interactions in osteosarcoma. Therefore, explicating regulations to restore the anti-tumor function of PTEN might provide novel targeted therapies for osteosarcoma. Preclinical evidence suggested directly targeting the altered PTEN in osteosarcoma was promising. Current clinical application of PTEN related therapies in osteosarcoma are PI3K/mTOR inhibitors, and these drugs have shown the favorable efficacy in patients with advanced osteosarcoma.

Osteosarcoma and Epidermoid Cyst in the Cerebellopontine Angle of an Adult

BACKGROUND

Osteosarcoma is a common malignant bone tumor that occurs in children or adolescents but rarely in the skull. Epidermoid cysts, also known as cholesteatomas, represent approximately 0.2%-1.8% of all intracranial tumors. The occurrence of osteosarcoma with an epidermoid cyst is extremely rare.

CASE DESCRIPTION

A 41-year-old woman had both osteosarcoma and cholesteatoma in the left cerebellopontine angle. We resected the 2 tumors using the suboccipital retrosigmoid approach, and she received radiotherapy and chemotherapy after the surgery. One year after surgery, the patient is healthy and has recovered well.

CONCLUSIONS

Osteosarcomas and epidermoid cysts should be completely resected to prevent tumor recurrence and aseptic meningitis. Postoperative osteosarcoma treatment should include radiotherapy and chemotherapy to improve the survival rate of patients. It is hoped that this report will help clinicians in diagnosis and treatment of patients with similar conditions.

Overexpression of Regucalcin Suppresses the Growth of Human Osteosarcoma Cells in Vitro: Repressive Effect of Extracellular Regucalcin

Regucalcin plays a pivotal role as a suppressor of human carcinogenesis, and downregulation of regucalcin expression may contribute to the promotion of human osteosarcoma. Overexpression of regucalcin suppressed the proliferation of Saos-2 human osteosarcoma cells in vitro and decreased the protein levels of multiple signaling components, transcription factors, and tumor suppressors. Interestingly, extracellular regucalcin repressed colony formation and proliferation of Saos-2 cells, and reduced the protein levels of multiple signaling components, cell cycle inhibitor, and various transcription factors. Thus, regucalcin suppressed the growth of human osteosarcoma cells, providing a novel strategy with the gene therapy for treatment of osteosarcoma.

New Insights about the Wnt/β-Catenin Signaling Pathway in Primary Bone Tumors and Their Microenvironment: A Promising Target to Develop Therapeutic Strategies?

Osteosarcoma and Ewing sarcoma are the most common malignant primary bone tumors mainly occurring in children, adolescents and young adults. Current standard therapy includes multidrug chemotherapy and/or radiation specifically for Ewing sarcoma, associated with tumor resection. However, patient survival has not evolved for the past decade and remains closely related to the response of tumor cells to chemotherapy, reaching around 75% at 5 years for patients with localized forms of osteosarcoma or Ewing sarcoma but less than 30% in metastatic diseases and patients resistant to initial chemotherapy. Despite Ewing sarcoma being characterized by specific EWSR1-ETS gene fusions resulting in oncogenic transcription factors, currently, no targeted therapy could be implemented. It seems even more difficult to develop a targeted therapeutic strategy in osteosarcoma which is characterized by high complexity and heterogeneity in genomic alterations. Nevertheless, the common point between these different bone tumors is their ability to deregulate bone homeostasis and remodeling and divert them to their benefit. Therefore, targeting different actors of the bone tumor microenvironment has been hypothesized to develop new therapeutic strategies. In this context, it is well known that the Wnt/β-catenin signaling pathway plays a key role in cancer development, including osteosarcoma and Ewing sarcoma as well as in bone remodeling. Moreover, recent studies highlight the implication of the Wnt/β-catenin pathway in angiogenesis and immuno-surveillance, two key mechanisms involved in metastatic dissemination. This review focuses on the role played by this signaling pathway in the development of primary bone tumors and the modulation of their specific microenvironment.

Upregulation of miR-214 Induced Radioresistance of Osteosarcoma by Targeting PHLDA2 via PI3K/Akt Signaling

Osteosarcoma is an aggressive bone tumor with high resistance to radiotherapy. Pleckstrin homology-like domain family A member 2 (PHLDA2) displays low expression in human osteosarcoma as a proapoptosis factor. miRNAs have been shown to be important in modulating translation and therapeutic responsiveness in solid tumors. Herein, we used luciferase assay to show that miR-214 downregulates the PHLDA2 expression by targeting its 3′-untranslated region (UTR). A high level of miR-214 was identified in tumor tissues from 30 osteosarcoma patients via qPCR analysis, associated positively with lung metastasis. Ectopic expression miR-214 enhanced radioresistance in osteosarcoma cells, with decreased IR-induced apoptosis. Moreover, the depletion of miR-214 enhanced radiosensitivity in both osteosarcoma cells and mouse xenograft models. Importantly, we showed that miR-214 regulated the activation of phosphatidylinositol-3-kinase/Akt signaling pathway by inhibiting PHLDA2. Finally, the introduction of PHLDA2 cDNA lacking the 3′-UTR or treatment with Akt inhibitor LY294002 partially abrogated miR-214-induced radioresistance. In summary, our results reveal that the upregulation of miR-214 as a frequent event in osteosarcoma contributes to radioresistance by regulating the PHLDA2/Akt pathway. The miR-214/PHLDA2/Akt axis provides a new avenue toward understanding the mechanism of radiosensitivity and may be a potential target for osteosarcoma intervention.

GAPLINC is a predictor of poor prognosis and regulates cell migration and invasion in osteosarcoma

Gastric adenocarcinoma predictive long intergenic non-coding (GAPLINC) is a novel long non-coding RNA (lncRNA) and has been found to function as an oncogenic lncRNA in gastric cancer, colorectal cancer, and bladder cancer. The expression status and biological function of GAPLINC in osteosarcoma are still unknown. Thus, we analyzed the association between GAPLINC expression and clinicopathological characteristics in osteosarcoma clinical samples, and conducted loss-of-function study in osteosarcoma cell lines. In our results, GAPLINC expression is elevated in osteosarcoma tissues and cell lines, and correlated with advanced Enneking stage, present distant metastasis, and poor histological grade. Survival analyses indicated that GAPLINC expression was negatively associated with overall survival, and GAPLINC high-expression was an independent risk factor in osteosarcoma patients. The in vitro studies showed knockdown of GAPLINC depressed osteosarcoma cell migration and invasion via inhibiting CD44 expression, but no effect on cell proliferation. In conclusion, GAPLINC may serve as a potential biomarker for predicting prognosis and developing therapy for osteosarcoma.