Clinical significance of hypoxia-inducible factor 1 and VEGF-A in osteosarcoma

Microenvironment matters: insights from the FOSTER consortium on microenvironment-driven approaches to osteosarcoma therapy

Osteosarcoma (OS), a prevalent malignant bone tumor, has seen limited progress in treatment efficacy and patient outcomes over decades. Recent insights into the tumor microenvironment (TME) have revealed its crucial role in tumor progression and therapeutic resistance, particularly in OS. This review offers a comprehensive exploration of the OS microenvironment, meticulously dissecting its crucial components: the mesenchymal stromal TME, the immune microenvironment, hypoxia-induced adaptations, and the impact of the physical microenvironment. By demonstrating how these elements collectively drive tumor proliferation, immune evasion, and invasion, this review explores the intricate molecular and cellular dynamics at play. Furthermore, innovative approaches targeting the OS microenvironment, such as immunotherapies, are presented. This review highlights the importance of the TME in OS progression and its potential as a source of novel therapeutic strategies, offering new hope for improved patient outcomes.

Prognostic Significance of Microvessel Density and Hypoxic Markers in Canine Osteosarcoma: Insights into Angiogenesis and Tumor Aggressiveness

Canine osteosarcoma (OSA) is an aggressive and highly malignant tumor of bone with a poor prognosis and it mirrors the disease in humans. Angiogenesis, the formation of new blood vessels, is driven by hypoxia-induced factors such as HIF-1α and VEGF, both of which play a crucial role in tumor growth and metastasis. However, the role of angiogenesis in OSA remains a topic of ongoing debate. This study aimed to investigate the relationship between angiogenesis, measured by intratumoral microvessel density (MVD), hypoxic markers, and clinical outcomes in 28 dogs diagnosed with appendicular OSA. Clinicopathological data such as age, breed distribution, tumor localization, histopathological subtypes, and metastatic behavior were consistent with reported epidemiologic characteristics of canine OSA, though no significant correlation was found among these variables. The results indicated a significant association between higher MVD and high-grade OSA (p = 0.029), suggesting that increased tumor vascularization is linked to more aggressive tumor behavior. Additionally, elevated VEGF expression was strongly correlated with disease-free interval DFI), with a p-value of 0.045. Although HIF-1α positivity showed a trend towards poorer survival, the results did not reach statistical significance (p = 0.07). These findings highlight the potential role of VEGF as a valuable prognostic marker in canine OSA, which could have potentially important implications for therapeutic targeting and clinical management of the disease. This study advances the understanding of angiogenesis in canine OSA, while emphasizing the need for continued research into the complex mechanisms regulating the interplay between hypoxia, angiogenesis and tumor progression.

Advances in prognostic models for osteosarcoma risk

The risk prognosis model is a statistical model that uses a set of features to predict whether an individual will develop a specific disease or clinical outcome. It can be used in clinical practice to stratify disease severity and assess risk or prognosis. With the advancement of large-scale second-generation sequencing technology, along Prognosis models for osteosarcoma are increasingly being developed as large-scale second-generation sequencing technology advances and clinical and biological data becomes more abundant. This expansion greatly increases the number of prognostic models and candidate genes suitable for clinical use. This article will present the predictive effects and reliability of various prognosis models, serving as a reference for their evaluation and application.

Unveiling the Protective Role of Melatonin in Osteosarcoma: Current Knowledge and Limitations

Melatonin, an endogenous neurohormone produced by the pineal gland, has received increased interest due to its potential anti-cancer properties. Apart from its well-known role in the sleep-wake cycle, extensive scientific evidence has shown its role in various physiological and pathological processes, such as inflammation. Additionally, melatonin has demonstrated promising potential as an anti-cancer agent as its function includes inhibition of tumorigenesis, induction of apoptosis, and regulation of anti-tumor immune response. Although a precise pathophysiological mechanism is yet to be established, several pathways related to the regulation of cell cycle progression, DNA repair mechanisms, and antioxidant activity have been implicated in the anti-neoplastic potential of melatonin. In the current manuscript, we focus on the potential anti-cancer properties of melatonin and its use in treating and managing pediatric osteosarcoma. This aggressive bone tumor primarily affects children and adolescents and is treated mainly by surgical and radio-oncological interventions, which has improved survival rates among affected individuals. Significant disadvantages to these interventions include disease recurrence, therapy-related toxicity, and severe/debilitating side effects that the patients have to endure, significantly affecting their quality of life. Melatonin has therapeutic effects when used for treating osteosarcoma, attributed to its ability to halt cancer cell proliferation and trigger apoptotic cell death, thereby enhancing chemotherapeutic efficacy. Furthermore, the antioxidative function of melatonin alleviates harmful side effects of chemotherapy-induced oxidative damage, aiding in decreasing therapeutic toxicities. The review concisely explains the many mechanisms by which melatonin targets osteosarcoma, as evidenced by significant results from several in vitro and animal models. Nevertheless, if further explored, human trials remain a challenge that could shed light and support its utility as an adjunctive therapeutic modality for treating osteosarcoma.

Hypoxia inducible factor-1ɑ as a potential therapeutic target for osteosarcoma metastasis

Osteosarcoma (OS) is a malignant tumor originating from mesenchymal tissue. Pulmonary metastasis is usually present upon initial diagnosis, and metastasis is the primary factor affecting the poor prognosis of patients with OS. Current research shows that the ability to regulate the cellular microenvironment is essential for preventing the distant metastasis of OS, and anoxic microenvironments are important features of solid tumors. During hypoxia, hypoxia-inducible factor-1α (HIF-1α) expression levels and stability increase. Increased HIF-1α promotes tumor vascular remodeling, epithelial-mesenchymal transformation (EMT), and OS cells invasiveness; this leads to distant metastasis of OS cells. HIF-1α plays an essential role in the mechanisms of OS metastasis. In order to develop precise prognostic indicators and potential therapeutic targets for OS treatment, this review examines the molecular mechanisms of HIF-1α in the distant metastasis of OS cells; the signal transduction pathways mediated by HIF-1α are also discussed.

Progresses in Fluorescence Imaging Guidance for Bone and Soft Tissue Sarcoma Surgery

R0 surgical resection is the preferred treatment for bone and soft tissue sarcoma. However, there is still a lack of precise technology that can visualize bone and soft tissue sarcoma during surgery to assist the surgeon in judging the tumor surgical boundary. Fluorescence imaging technology has been used in the diagnosis of cancer. It is a simple and essentially safe technique that takes no additional time during the operation. Intraoperative fluorescence imaging has potential application prospects in assisting the surgeons in judging the tumor boundary and improving the accuracy of surgical resection. This review mainly starts with clinical studies, animal experimentation, and newly designed probes of intraoperative fluorescence imaging of bone and soft tissue sarcoma, to appraise the application prospects of fluorescence imaging technology in bone and soft tissue sarcoma.

Correlation of vascular endothelial growth factor with survival and pathological characteristics of patients with osteosarcoma: A systematic review and meta-analysis

OBJECTIVE

This study aimed to assess the prognostic role of vascular endothelial growth factor (VEGF) expression in osteosarcoma.

METHODS

Systematic searches of PubMed, Embase, CINAHL, Cochrane Library, ScienceDirect, and Web of Science were conducted. The correlation between VEGF expression and patients' survival was our primary endpoint. The secondary endpoints were the associations between VEGF level and patients' sociodemographic and pathological characteristics. The pooled hazard ratio (HR) or odd ratio (OR) and corresponding 95% confidence intervals (CIs) were obtained to assess the associations between VEGF expression and the target factors. Subgroup and meta-regression analyses were conducted to explore potential factors that associated with VEGF efficacy.

RESULTS

The combined HR suggested that a positive VEGF status has a negative impact on overall survival (OS) (HR = 2.58; 95% CI, 2.09-3.19; P < 0.0001) and disease-free survival (DFS) (HR = 2.54; 95% CI, 1.84-3.50; P < 0.0001) in patients with osteosarcoma. Meta-regression analysis ruled out the influence of cut-off value, disease stage, histological subtype, disease grade, tumour location, geographic area, publication year, and method of HR acquisition on heterogeneity. Results showed that VEGF expression was closely correlated with tumour staging, chemotherapy response, and metastasis.

CONCLUSION

Based on the study results, VEGF could serve as an effective biomarker of prognosis in patients with osteosarcoma. Besides, VEGF was related to increased tumour malignancy, which might help guide clinical decision-making regarding therapy and outcomes.

Sphingosine Kinase-1 Is Overexpressed and Correlates with Hypoxia in Osteosarcoma: Relationship with Clinicopathological Parameters

The Sphingosine kinase-1/Sphingosine 1-Phosphate (SphK1/S1P) signaling pathway is overexpressed in various cancers, and is instrumental for the adaptation to hypoxia in a number of solid tumor models, but no data are available in osteosarcoma. Here we report that SphK1 and the S1P₁ receptor are involved in HIF-1α accumulation in hypoxic osteosarcoma cells. FTY720 (Fingolimod), which targets SphK1 and S1P_1, prevented HIF-1α accumulation, and also inhibited cell proliferation in both normoxia and hypoxia unlike conventional chemotherapy. In human biopsies, a significant increase of SphK1 activity was observed in cancer compared with normal bones. In all sets of TMA samples (130 cases of osteosarcoma), immunohistochemical analysis showed the hypoxic marker GLUT-1, SphK1 and S1P₁ were expressed in tumors. SphK1 correlated with the GLUT-1 suggesting that SphK1 is overexpressed and correlates with intratumoral hypoxia. No correlation was found between GLUT-1 or SphK1 and response to chemotherapy, but a statistical difference was found with increased S1P₁ expression in patients with poor response in long bone osteosarcomas. Importantly, multivariate analyses showed that GLUT-1 was associated with an increased risk of death in flat bone, whereas SphK1 and S1P₁ were associated with an increased risk of death in long bones.

Osteosarcoma and Metastasis

Osteosarcoma is the most common primary bone malignancy in adolescents. Its high propensity to metastasize is the leading cause for treatment failure and poor prognosis. Although the research of osteosarcoma has greatly expanded in the past decades, the knowledge and new therapy strategies targeting metastatic progression remain sparse. The prognosis of patients with metastasis is still unsatisfactory. There is resonating urgency for a thorough and deeper understanding of molecular mechanisms underlying osteosarcoma to develop innovative therapies targeting metastasis. Toward the goal of elaborating the characteristics and biological behavior of metastatic osteosarcoma, it is essential to combine the diverse investigations that are performed at molecular, cellular, and animal levels from basic research to clinical translation spanning chemical, physical sciences, and biology. This review focuses on the metastatic process, regulatory networks involving key molecules and signaling pathways, the role of microenvironment, osteoclast, angiogenesis, metabolism, immunity, and noncoding RNAs in osteosarcoma metastasis. The aim of this review is to provide an overview of current research advances, with the hope to discovery druggable targets and promising therapy strategies for osteosarcoma metastasis and thus to overcome this clinical impasse.

The role of vascular endothelial growth factor as a prognostic and clinicopathological marker in osteosarcoma: a systematic review and meta-analysis

BACKGROUND

In recent years, numerous investigations have been conducted to determine the clinical significance and critical functions of vascular endothelial growth factor (VEGF) in various malignant cancers. The purpose of this meta-analysis was to comprehensively evaluate the prognostic and clinicopathological value of VEGF in patients with osteosarcoma.

METHODS

We performed a systematic literature retrieval of available databases. Odds ratios (ORs) or standard mean difference (SMD) for clinicopathological parameters, hazard ratios (HRs) for overall survival and disease-free survival were calculated to assess the correlation between VEGF expression and prognosis in patients with osteosarcoma.

RESULTS

A total of 22 studies with 1144 patients were included in our study. Pooled analyses showed that VEGF overexpression predicted worse overall survival (HR, 2.42; 95% CI, 1.87-3.11, p < 0.001) and disease-free survival (HR, 2.604; 95% CI, 1.698-3.995, p < 0.001), respectively. Furthermore, investigation regarding osteosarcoma clinicopathologic characteristics suggested that high VEGF expression was significantly associated with metastasis (OR, 4.39; 95% CI, 2.77-6.95; p < 0.001), clinical stage (OR, 0.73; 95% CI, 0.62-0.87; p < 0.001), and microvessel density (SMD, 3.33, 95% CI,1.57-5.10, p < 0.001), but not associated with tumor location, gender, age, local recurrence, and chemotherapy response.

CONCLUSION

Our meta-analysis findings suggest that elevated VEGF expression may be a predictive biomarker for poor prognosis and adverse clinicopathological characteristics in patients with osteosarcoma.

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.

Hypoxia stimulates the migration and invasion of osteosarcoma via up-regulating the NUSAP1 expression

Osteosarcoma is a highly aggressive malignant tumor, which most commonly occurs in children and adolescents. This study aims to reveal that hypoxia promotes the invasion of osteosarcoma cells by up-regulating the expression of NUSAP1. The expression of HIF-1α and NUSAP1 was significantly up-regulated in MG63 cells cultured in hypoxia for 6–36 h. Furthermore, hypoxia induced the migration and invasion of MG63 cells and regulated the level of E-cad, N-cad, Vimentin, Snail, Slug, MMP2, and MMP9 proteins. Importantly, knockdown of NUSAP1 inhibited hypoxia-induced cell migration and invasion. In the hypoxia microenvironment, the addition of HIF-1α inhibitor or the transfection of siRNA specifically targeting HIF-1α significantly reduced the expression of HIF-1α and NUSAP1 and markedly inhibited the migration and invasion of MG63 cells under the hypoxia microenvironment. In conclusion, hypoxia induced the expression of NUSAP1 in a HIF-1α-dependent manner, stimulating the migration and invasion of MG63 cells.

Hypoxia increases the expression of stem cell markers in human osteosarcoma cells

Osteosarcoma (OS) is the most common primary malignant tumor of bone. It is a common phenomenon that osteosarcoma cells have a hypoxic microenvironment. Hypoxia can dedifferentiate cells of several malignant tumor types into stem cell-like phenotypes. However, the role of hypoxia in stemness induction and the expression of cancer stem cell (CSC) markers in human osteosarcoma cells has not been reported. The present study examined the effects of hypoxia on stem-like cells in the human osteosarcoma MNNG/HOS cells. Under the incubation with 1% oxygen, the expression of CSCs markers (Oct-4, Nanog and CD133) in MNNG/HOS cells were increased. Moreover, MNNG/HOS cells cultured under hypoxic conditions were more likely to proliferate into spheres and resulted in larger xenograft tumor. Hypoxia also increased the mRNA and protein levels of hypoxia-inducible factor (HIF)-1α. Then rapamycin was used, which has been shown to lower HIF-1α protein level, to inhibit the hypoxic response. Rapamycin suppressed the expression of HIF-1α protein and CSCs markers (Oct4, Nanog and CD133) in MNNG/HOS cells. In addition, pretreatment with rapamycin reduced the efficiency of MNNG/HOS cells in forming spheres and xenograft tumors. The results demonstrated that hypoxia (1% oxygen) can dedifferentiate some of the MNNG/HOS cells into stem cell-like phenotypes, and that the mTOR signaling pathway participates in this process via regulating the expression of HIF-1α protein.

Clinical significance and in vitro cellular regulation of hypoxia mimicry on HIF-1α and downstream genes in canine appendicular osteosarcoma

Cellular adaptation to a hypoxic microenvironment is essential for tumour progression and is largely mediated by HIF-1α and hypoxia-regulated factors, including CXCR4, VEGF-A and GLUT-1. In human osteosarcoma, hypoxia is associated with resistance to chemotherapy as well as with metastasis and poor survival, whereas little is known about its role in canine osteosarcoma (cOSA). This study aimed primarily to evaluate the prognostic value of several known hypoxic markers in cOSA. Immunohistochemical analysis for HIF-1α, CXCR4, VEGF-A and GLUT-1 was performed on 56 appendicular OSA samples; correlations with clinicopathological features and outcome was investigated. The second aim was to investigate the in vitro regulation of markers under chemically induced hypoxia (CoCl₂). Two primary canine osteosarcoma cell lines were selected, and Western blotting, immunofluorescence and qRT-PCR were used to study protein and gene expression. Dogs with high-grade OSA (35.7%) were more susceptible to the development of metastases (P = 0.047) and showed high HIF-1α protein expression (P = 0.007). Moreover, HIF-1α overexpression (56%) was correlated with a shorter disease-free interval (DFI; P = 0.01), indicating that it is a reliable negative prognostic marker. The in vitro experiments identified an accumulation of HIF-1α in cOSA cells after chemically induced hypoxia, leading to a significant increase in GLUT-1 transcript (P = 0.02). HIF-1α might be a promising prognostic marker, highlighting opportunities for the use of therapeutic strategies targeting the hypoxic microenvironment in cOSA. These results reinforce the role of the dog as a comparative animal model since similar hypoxic mechanisms are reported in human osteosarcoma.

Pseudogene MSTO2P enhances hypoxia-induced osteosarcoma malignancy by upregulating PD-L1

Hypoxia has been shown to be related to osteosarcoma development and progression. Pseudogene MSTO2P was reported to be dysregulated in hepatocellular carcinoma and lung cancer. However, the mechanism by which MSTO2P-modulated osteosarcoma remains unclear. MSTO2P and PD-L1 expression levels were examined by RT-qPCR and westernblot. Tumor cell invasion was determined by tranwell assay. EMT process was probed by determining E-cadherin and Vimentin levels. Soft agar assay was used to examine anchorage-independent growth of osteosarcoma cells. In vivo tumor growth was measured by xenografting tumor experiment. Hypoxia treatment promoted cell growth, invasion and EMT of osteosarcoma cells. MSTO2P knockdown led to attenuated cell growth, invasion and EMT of osteosarcoma cells under hypoxia condition. More interestingly, our data revealed that MSTO2P was positively associated with tumor growth in immunodeficient mice and human clinical tissues. PD-L1 was shown to act as a key effector for MSTO2P-regulated osteosarcoma progression under hypoxia condition. In conclusion, we unravel a novel mechanism for explaining MSTO2P-involved osteosarcoma progression under hypoxia condition, which will facilitate development of potential diagnostic and therapeutical strategies for osteosarcoma.

Association of JMJD2B and Hypoxia-Inducible Factor 1 Expressions with Poor Prognosis in Osteosarcoma

Background

JMJD2B has been reported to be implicated in malignant tumors. This study is aimed at exploring the expression and prognostic significance of JMJD2B in osteosarcoma and its association with hypoxia-inducible factor 1 (HIF1).

Methods

The histopathological and clinical characteristics were retrospectively reviewed from 53 osteosarcoma patients. JMJD2B and HIF1 were examined by immunohistochemical staining of paraffin-embedded osteosarcoma samples, and their association with clinical characteristics was examined by Spearman's test. Overall survival was examined by Kaplan-Meier analysis, and prognostic factors were identified by univariate and multivariate regression analyses.

Results

JMJD2B and HIF1 expression levels were both significantly associated with Enneking stage, distant metastasis, and neoadjuvant chemotherapy, and the JMJD2B and HIF1 expressions were positively correlated (p < 0.001, R = 0.752). In addition, univariate analysis showed that the expression of both JMJD2B and HIF1 was significantly associated with overall survival, but multivariate analysis showed that only JMJD2B expression was significantly associated with overall survival in osteosarcoma patients.

Conclusions

JMJD2B and HIF1 expression levels show significant correlation with osteosarcoma progression, and JMJD2B could predict poor prognosis of osteosarcoma patients.

Role of VEGFs/VEGFR-1 Signaling and its Inhibition in Modulating Tumor Invasion: Experimental Evidence in Different Metastatic Cancer Models

The vascular endothelial growth factor (VEGF) family members, VEGF-A, placenta growth factor (PlGF), and to a lesser extent VEGF-B, play an essential role in tumor-associated angiogenesis, tissue infiltration, and metastasis formation. Although VEGF-A can activate both VEGFR-1 and VEGFR-2 membrane receptors, PlGF and VEGF-B exclusively interact with VEGFR-1. Differently from VEGFR-2, which is involved both in physiological and pathological angiogenesis, in the adult VEGFR-1 is required only for pathological angiogenesis. Besides this role in tumor endothelium, ligand-mediated stimulation of VEGFR-1 expressed in tumor cells may directly induce cell chemotaxis and extracellular matrix invasion. Furthermore, VEGFR-1 activation in myeloid progenitors and tumor-associated macrophages favors cancer immune escape through the release of immunosuppressive cytokines. These properties have prompted a number of preclinical and clinical studies to analyze VEGFR-1 involvement in the metastatic process. The aim of the present review is to highlight the contribution of VEGFs/VEGFR-1 signaling in the progression of different tumor types and to provide an overview of the therapeutic approaches targeting VEGFR-1 currently under investigation.

Hypoxia promotes osteosarcoma cell proliferation and migration through enhancing platelet-derived growth factor-BB/platelet-derived growth factor receptor-β axis

Osteosarcoma is a primary malignant bone tumor, characterized by high therapeutic resistance and poor outcomes, due to unclear pathological mechanisms. It has been shown recently that the platelet-derived growth factor (PDGF)/platelet-derived growth factor receptor (PDGFR) pathway is closely associated with the pathogenesis of osteosarcoma. Hypoxia is a critical hallmark of tumor microenvironment that promotes the malignant phenotype in many solid tumors and a fundamental impediment to effective tumor therapy. In this study, we confirmed that hypoxia is an important feature of osteosarcoma, validated by the positive immunohistochemistry staining of hypoxia marker hypoxia-inducible factor-1α (HIF-1α) and carbonic anhydrase IX (CAIX) in osteosarcoma tissue samples. More importantly, we discovered that hypoxia could transcriptionally upregulate the expression of both PDGF-BB and PDGFR-β in osteosarcoma cells in vitro. Likewise, we also established that hypoxia-induced PDGF-BB is strongly related to the enhanced cell proliferation and migration, by activating AKT, ERK1/2, and STAT3 signaling pathways. Notably, when using an antibody to block the autocrine of PDGF-BB, cell proliferation and migration were partially aborted in hypoxia. Collectively, we demonstrated that the hypoxia-activated PDGF-BB/PDGFR-β axis plays essential roles in osteosarcoma progression. These findings may shed light on the molecular pathogenesis of osteosarcoma, and provide a novel strategy for osteosarcoma treatment by combinational targeting hypoxia and PDGF-BB/PDGFR signaling.

Clinicopathological and prognostic value of hypoxia-inducible factor-1α in patients with bone tumor: a systematic review and meta-analysis

Background

Recently, many studies have shown the role of hypoxia-inducible factor-1α (HIF-1α) expression in the outcome of bone tumor. However, the results remain inconclusive. It is necessary to carry out a meta-analysis of all the current available data to clarify the relationship between HIF-1α and survival or clinicopathological features of bone tumor.

Methods

PubMed, Cochrane Library, Web of Science, China National Knowledge Internet, and Wanfang databases were used to search the relationship between HIF-1α and bone tumor. Articles investigating clinicopathological and prognostic value of HIF-1α in bone tumor patients were enrolled in this meta-analysis. Overlapping articles, duplicate data, reviews, case reports, and letters without original data were excluded. The pooled risk ratios (RRs) and hazard ratios (HRs) were used to evaluate the clinicopathological and prognostic value of HIF-1α on bone tumor patients, respectively.

Results

A total of 28 studies including 1443 patients were included in this meta-analysis, which were involved in three different types of bone tumor including 3 chondrosarcomas, 2 giant cell tumors of bone, and 23 osteosarcomas. Our results showed that high expression levels of HIF-1α were associated with poorer OS (overall survival) (HR = 2.61, 95% CI 2.11–3.23, P <  0.001) and shorter DFS (disease-free survival) (HR = 2.02, 95% CI 1.41–2.89, P <  0.001) in bone tumor. In addition, this study also analyzed the role of HIF-1α expression in clinicopathological features, which were closely related with the severity of bone tumor, including differentiation, clinical stage, metastasis, and microvessel density. Our results indicated that HIF-1α overexpression was significantly associated with differentiation (RR = 1.56, 95% CI 1.00–2.43, P = 0.049), clinical stage (RR = 1.75, 95% CI 1.25–2.45, P = 0.001), metastasis (RR = 1.78, 95% CI 1.58–2.00, P <  0.001), and microvessel density (SMD = 2.34, 95% CI 1.35–3.34, P <  0.001) of bone tumor.

Conclusions

HIF-1α overexpression indicated an unfavorable factor for OS and DFS in bone tumor, suggesting that HIF-1α may serve as a potential prognostic marker for bone tumor.

Electronic supplementary material

The online version of this article (10.1186/s13018-019-1101-5) contains supplementary material, which is available to authorized users.

Hypoxia-inducible factor-1 promotes cancer progression through activating AKT/Cyclin D1 signaling pathway in osteosarcoma

OBJECTIVE

Osteosarcoma is an aggressive malignant neoplasm, which commonly afflicts patients of 20-30 years of age, and its morbidity has increased markedly in recent years. Certain genes and signal pathways have been identified to exert key roles in osteosarcoma progression. Here, we set out to characterize in more detail of the role of HIF-1/AKT/Cyclin D1 pathway in the progression of osteosarcoma.

METHODS

Immunohistochemistry, western blot and qPCR were used to test the protein or mRNA levels of HIF-1 in osteosarcoma tissues or adjacent nontumor tissues. MTT, clone formation, wound healing, Transwell, in vivo tumorigenesis, flow cytometry and western blot analysis were used to determine cell proliferation, clone formation ability, migration, invasion, tumorigenesis, and cell apoptosis in MG63 and U2OS cells, respectively. Immunoprecipitation and immunofluorescence assays were performed to investigate the protein-protein interaction between HIF-1α and proteins related to signal pathways.

RESULTS

HIF-1 was overexpressed in osteosarcoma tissues and cell lines, which promoted cell proliferation, clone formation, migration, invasion and inhibited cell apoptosis. Results also demonstrated that HIF-1 combined with AKT, and there might be a positive loop between the two proteins of HIF-1 and AKT, then the protein-protein interaction up-regulated the expression of Cyclin D1 in protein level, but not mRNA level, made Cyclin D1 protein more stable, triggered cell proliferation, clone formation, tumorigenesis, but inhibited cell apoptosis.

CONCLUSIONS

The present study showed that HIF-1 modulated Cyclin D1 expression might through shaping a positive loop with AKT proteins. Additionally, HIF-1α promoted the tumor cells growth, migration and invasion in osteosarcoma through the activation of the AKT/Cyclin D1 signal cascade. We proposed that HIF-1 could be served as a marker for distinguishing osteosarcoma and an effective therapeutic target for osteosarcoma.

Established Models and New Paradigms for Hypoxia-Driven Cancer-Associated Bone Disease

The five-year survival rate for primary bone cancers is ~ 70% while almost all cases of secondary metastatic bone cancer are terminal. Hypoxia, the deficiency of oxygen which occurs as the rate of tumour growth exceeds the supply of vascularisation, is a key promoter of tumour progression. Hypoxia-driven effects in the primary tumour are wide ranging including changes in gene expression, dysregulation of signalling pathways, resistance to chemotherapy, neovascularisation, increased tumour cell proliferation and migration. Paget's seed and soil theory states that for a metastasising tumour cell 'the seed' it requires the correct microenvironment 'soil' to colonise. Why and how metastasising tumour cells colonise the bone is a complex and intriguing problem. However, once present tumour cells are able to disrupt bone homeostasis through increasing osteoclast activity and downregulating osteoblast function. Osteoclast resorption releases growth factors from the bone matrix that subsequently contribute to the proliferation of invasive tumour cells creating the vicious cycle of bone loss and metastatic cancer progression. Recently, we have shown that hypoxia increases expression and release of lysyl oxidase (LOX) from primary mammary tumours, which in turn disrupts bone homeostasis to favour osteolytic degradation to create pre-metastatic niches in the bone microenvironment. We also demonstrated how treatment with bisphosphonates could block this cancer-induced bone remodelling and reduce secondary bone metastases. This review describes the roles of hypoxia in primary tumour progression to metastasis, with a focus on key signalling pathways and treatment options to reduce patient morbidity and increase survival.

Fibroblast activation protein-α in tumor cells promotes colorectal cancer angiogenesis via the Akt and ERK signaling pathways

Fibroblast activation protein-α (FAP-α) is a cell surface serine protease of the post-prolyl peptidase family, and stromal FAP-α expression may serve important functions in tumor occurrence and progression. In recent years, FAP-α expression in tumor cells has been detected in a number of types of tumor, and its roles in tumor growth and metastasis have been reported. However, the presence of FAP-α in colorectal cancer (CRC) cells lacks sufficient evidence and its role in angiogenesis remains unknown. The present study confirmed FAP-α expression in CRC cells at the tissue and cellular level, using immunohistochemistry and western blot analysis, respectively; it additionally identified that FAP-α in CRC cells was positively associated with vascular endothelial growth factor (VEGF)-A expression and microvessel density in stained tissue samples for the first time. In addition, western blotting identified that FAP-α overexpression in SW1116 cells significantly upregulated VEGF-A expression, and silencing of FAP-α in HT29 cells markedly inhibited VEGF-A expression. Survival analysis demonstrated that patients with high expression of FAP-α and VEGF-A had the shortest survival time. To detect the effects of FAP-α on human umbilical vein endothelial cells (HUVECs), conditioned medium (CM) from CRC cell lines was used and it was identified that CM from SW1116 cells with overexpressed FAP-α exhibited significantly increased VEGF-R2, phosphorylated extracellular signal-regulated kinase (p-ERK) and p-RAC-α serine/threonine-protein kinase (Akt) in HUVECs, in addition to the proliferation rate. Conversely, CM from HT29 cells with FAP-α silenced exhibited a significantly inhibited proliferation rate. Molecular mechanism analysis demonstrated that p-ERK and p-Akt in SW1116 and HT29 cells were affected by alterations in FAP-α expression, and treatment with a p-ERK inhibitor (U0126) and p-Akt inhibitor (LY294002) ameliorated VEGF-A upregulation induced by FAP-α overexpression. All the results confirmed the presence of FAP-α in CRC cells and suggested that FAP-α may effectively promote angiogenesis in CRC via the Akt and ERK signaling pathways.

Combined analysis of ChIP-seq and gene microarray datasets identify the E2-mediated genes in ERα-dependent manner in osteosarcoma

Osteosarcoma is a common bone tumor which is affected by E2, the most representative estrogen. Gene regulation function of E2 is highly dependent on estrogen receptor. The purpose of this study was to explore the gene regulation patterns of E2 through estrogen receptor α (ESR1) in osteosarcoma based on the combined analysis of ChIP-seq and gene microarray. All of the datasets were downloaded from the Gene Expression Omnibus (GEO). Differential expression genes (DEGs) in E2 treated U2OS cells expressing ESR1 (U2OS-ERα) compared with those treated with vehicle were obtained based on R programming software. ESR1-specific binding sites (peaks) in E2 treated U2OS cells were identified through MACS. Overlaps between DEGs and ESR1 target genes which contained peaks in promoters were considered as reliable E2-mediated genes through ESR1 in osteosarcoma. Moreover, we conducted miRNA-Gene regulation analysis for those genes through miRWalk database to identify potential therapeutic targets for the genes. Functional enrichment analysis of DEGs indicated their potential involvement in cancer, and cell activity-related processes. Fifteen overlaps were identified between DEGs and target genes of ESR1, of which 12 were found to be regulated by miRNA. Several known estrogen response genes and novel genes were obtained in this study and they might provide potential therapeutic targets for osteosarcoma.

Curcumin inhibits hypoxia-induced proliferation and invasion of MG-63 osteosarcoma cells via downregulating Notch1

Curcumin is a biologically active ingredient abundantly present in the ground rhizomes of Curcuma longa with a wide range of bioactive properties, including antitumor effects. Hypoxia is a common characteristic of solid tumors, including osteosarcoma. However, whether curcumin has antitumor effects on osteosarcoma under hypoxic conditions, and its underlying molecular mechanisms, remain unclear. The present study demonstrated that the MG‑63 osteosarcoma cell line exhibited increased proliferation and enhanced invasiveness upon exposure to hypoxic conditions. However, these effects were prevented by curcumin treatment. Further investigation revealed that curcumin may inhibit Notch1 upregulation induced by hypoxia. Overexpression of Notch1 via Notch1 cDNA transfection ameliorated curcumin‑inhibited MG‑63 cell growth under hypoxic conditions. Taken together, these data revealed that curcumin may suppress the growth of osteosarcoma cells in hypoxia via inhibiting Notch1 signaling.

Prognosis value of Hypoxia-inducible factor-1α expression in patients with bone and soft tissue sarcoma: a meta-analysis

The prognostic significance of Hypoxia-inducible factor-1α (HIF-1α) in patients with bone and soft tissue sarcoma remains controversial. To investigate the impact of its expression on survival outcomes, we performed a meta-analysis. Comprehensive literature searches were conducted in PubMed, Web of Science, Embase and Cochrane Library. A total of 16 studies published from 2006 to 2015 were included. We found that expression of HIF-1α was significantly associated with higher rate of metastasis (RR 3.21, 95 % CI 2.12–4.84, P < 0.001), poorer overall survival (HR 2.05, 95 % CI 1.51–2.77, P < 0.001) and poorer disease-free survival (HR 2.05, 95 % CI 1.55–2.70, P < 0.001). In addition, when subgroup analysis was conducted according to histology type, the significant correlations to poor overall survival and disease-free survival were also observed in patients with osteosarcoma, chondrosarcoma and soft tissue sarcoma. Publication bias was not found and sensitivity analysis showed the results were stable. In conclusion, HIF-1α expression might be an effective predicative factor of poor prognosis for bone and soft tissue sarcoma.

Hypoxia-inducible factor-1 expression predicts osteosarcoma patients' survival: a meta-analysis

Osteosarcoma, the most common primary bone malignancy, is characterized by easily relapsing and metastasizing. Hypoxia-inducible factor-1 (HIF-1) plays an essential role in tumorigenesis, affecting tumor metabolism, differentiation, angiogenesis, proliferation and metastasis, and has been found to be associated with survival in patients with osteosarcoma. The possible prognostic value of HIF-1 was investigated in many studies, but the results were inconsistent. We therefore conducted a meta-analysis to elucidate the correlation of HIF-1 expression, analyzed by immunohistochemistry in osteosarcoma tissues, with prognosis. The association degree was assessed by calculation of the hazard ratio (HR) and risk ratio (RR) with corresponding 95% confidence intervals (CIs). Follow-up information was available for 486 patients from 7 studies. The results showed that high HIF-1 expression was associated with a worse prognosis when compared to low or undetectable HIF-1 expression, with an HR of 3.67 (95% CI 2.24-5.99; p<0.001) for overall survival (OS) and an RR of 3.72 (95% CI 2.26-6.13; p<0.001) for OS. The RR of 2.55 for disease-free survival (DFS) did not show any obvious relationship between a high level of HIF-1 and DFS (95% CI 0.95-6.87; p = 0.064). The stability of this result was tested by sensitivity analysis and no significant change was detected. This meta-analysis suggests that HIF-1 is an effective prognostic biomarker to predict OS in patients with osteosarcoma.

The impact of high co-expression of Sp1 and HIF1α on prognosis of patients with hepatocellular cancer

Transcription factor specificity protein 1 (Sp1) and hypoxia-inducible factor 1α (HIF1α) serve vital roles in tumor growth and metastasis. The present study aimed to evaluate the impact of co-expression of Sp1 and HIF1α on the prognosis of patients with hepatocellular cancer (HCC) using The Cancer Genome Atlas (TCGA) database and to validate the association between the expression levels of Sp1/HIF1α in HCC specimens and patient survival using immunohistochemical analysis. A total of 214 eligible patients with HCC from TCGA database were collected for the study. The expression profile of Sp1 and HIF1α were obtained from the TCGA RNAseq database. Clinicopathological characteristics, including age, height, weight, gender, race, ethnicity, family cancer history, serum α-fetoprotein (AFP), surgical procedures and TNM stage were collected. The Cox proportional hazards regression model and Kaplan-Meier curves were used to assess the relative factors. Receiver operating characteristic (ROC) curves for cancer-specific survival (CSS) prediction were plotted to compare the prediction ability of expression of Sp1 and HIF1α and their co-expression. The location and expression of Sp1 and HIF1α in the HCC tissues were detected by immunohistochemistry (IHC) to verify the association between these two genes and CSS. The results demonstrated that the expressions of Sp1 and HIF1α were significantly increased in the succumbed group (P=0.001), compared with the surviving group. The CSS rates were 60.1% at 3 years (1,067 days), 35.8% at 5 years (1,823 days) and 9.5% at 10 years (3,528 days). Multivariate Cox regression analysis demonstrated that only the high expression levels of Sp1 and HIF1α (≥2×103) were independent predictors for cancer mortality, with P=0.001 and P=0.029, respectively. The area under the curve for the ROC was found to be higher using the combination testing for two genes (0.751) in predicting cancer mortality, compared to a single gene (0.632 for Sp1 and 0.717 for HIF1α). Based on the cutoff points for gene expression, patients were divided into 3 groups: G1 (both genes <2×103), G2 (either gene ≥2×103) and G3 (both genes ≥2×103). The risk of cancer mortality increased with high expression of genes, and G3 exhibited a greater risk than G2 when compared with the G1 group (HR=5.420, 95% CI 2.767-10.616, P=0.001; HR=3.270, 95% CI 1.843-5.803, P=0.001). The IHC staining results indicated that patients who died of cancer presented with significantly higher expression levels of these genes compared with those that did not (P=0.001). In summary, high expression levels of Sp1 and HIF1α in HCC tissues were associated with poor prognosis; in particular, the co-expression of these two genes increased the risk of cancer mortality.

Genetic factors conferring metastasis in osteosarcoma

Osteosarcoma (OS) is a deadly bone malignancy affecting mostly children and adolescents. OS has outstandingly complex genetic alterations likely due to p53-independent genomic instability. Based on analysis of recent published research we claim existence of various genetic mechanisms of osteosarcomagenesis conferring great variability to different OS properties including metastatic potential. We also propose a model explaining how diverse genetic mechanisms occur and providing a framework for future research. P53-independent preexisting genomic instability, which precedes and frequently causes TP53 genetic alterations, is central in our model. In addition, our analyses reveal a possible cooperation between aberrantly activated HIF-1α and AP-1 genetic pathways in OS metastasis. We also review the involvement of noncoding RNA genes in OS metastasis.

Prognostic role of hypoxia-inducible factor-1 alpha expression in osteosarcoma: a meta-analysis

Background

Hypoxia-inducible factor-1α (HIF-1α) plays an important role in tumor progression and metastasis. A number of studies have investigated the association of HIF-1α with prognosis and clinicopathological characteristics of osteosarcoma but yielded inconsistent results.

Method

Systematic computerized searches were performed in PubMed, Embase, and Web of Science databases for relevant original articles. The pooled hazard ratios (HRs) and odds ratios (ORs) with corresponding confidence intervals (CIs) were calculated to assess the prognostic value of HIF-1α expression. The standard mean difference was used to analyze the continuous variable.

Results

Finally, nine studies comprising 486 patients were subjected to final analysis. Protein expression level of HIF-1α was found to be significantly related to overall survival (HR =3.0; 95% CI: 1.46–6.15), disease-free survival (HR =2.23; 95% CI: 1.26–3.92), pathologic grade (OR =21.33; 95% CI: 4.60–98.88), tumor stage (OR =10.29; 95% CI: 3.55–29.82), chemotherapy response (OR =9.68; 95% CI: 1.87–50.18), metastasis (OR =5.06; 95% CI: 2.87–8.92), and microvessel density (standard mean difference =2.83; 95% CI: 2.28–3.39).

Conclusion

This meta-analysis revealed that overexpression of HIF-1α is a predictive factor of poor outcomes for osteosarcoma. HIF-1α appeared to play an important role in prognostic evaluation and may be a potential target in antitumoral therapy.