Human chondrosarcoma secretes vascular endothelial growth factor to induce tumor angiogenesis and stores basic fibroblast growth factor for regulation of its own growth

Molecular In-Depth Characterization of Chondrosarcoma for Current and Future Targeted Therapies

Chondrosarcoma (CHS) are heterogenous, but as a whole, represent the second most common primary malignant bone tumor entity. Although knowledge on tumor biology has grown exponentially during the past few decades, surgical resection remains the gold standard for the treatment of these tumors, while radiation and differentiated chemotherapy do not result in sufficient cancer control. An in-depth molecular characterization of CHS reveals significant differences compared to tumors of epithelial origin. Genetically, CHS are heterogenous, but there is no characteristic mutation defining CHS, and yet, IDH1 and IDH2 mutations are frequent. Hypovascularization, extracellular matrix composition of collagen, proteoglycans, and hyaluronan create a mechanical barrier for tumor suppressive immune cells. Comparatively low proliferation rates, MDR-1 expression and an acidic tumor microenvironment further limit therapeutic options in CHS. Future advances in CHS therapy depend on the further characterization of CHS, especially the tumor immune microenvironment, for improved and better targeted therapies.

Systemic Therapy for Chondrosarcoma

OPINION STATEMENT

Clinical trial enrollment should be actively encouraged in all patients diagnosed with advanced, surgically unresectable chondrosarcoma (CS) due to the lack of consensus treatment recommendations. In the absence of an appropriate clinical trial, treatments are determined based on histologic subtype of CS with consideration given to targetable mutations (i.e., IDH1). Conventional CS is inherently resistant to cytotoxic chemotherapy and patients may benefit from antiangiogenic therapy including off-label use of pazopanib. Individuals harboring an IDH1 mutation may derive clinical benefit from ivosidenib, an IDH1 inhibitor. Upon progression and with functional status permitting, alternative options include mTOR inhibitors (sirolimus, temsirolimus) or other tyrosine kinase inhibitors (dasatinib), though no clear sequencing data exists. For dedifferentiated CS, conventional chemotherapies with osteosarcoma-like regimens are upfront options although prospective data is limited with minimal overall benefit. Alternative treatment options include immunotherapy with pembrolizumab or ivosidenib in IDH1-mutant, dedifferentiated CS, but questionable efficacy was observed in small sample sizes with either approach. In mesenchymal CS, treatment with Ewing sarcoma-like chemotherapy regimens may be considered, although data supporting its use is even more limited given its rarity.

Chondrosarcoma-from Molecular Pathology to Novel Therapies

Chondrosarcoma (CHS) is the second most common primary malignant bone sarcoma. Overall survival and prognosis of this tumor are various and often extreme, depending on histological grade and tumor subtype. CHS treatment is difficult, and surgery remains still the gold standard due to the resistance of this tumor to other therapeutic options. Considering the role of differentiation of CHS subtypes and the need to develop new treatment strategies, in this review, we introduced a multidisciplinary characterization of CHS from its pathology to therapies. We described the morphology of each subtype with the role of immunohistochemical markers in diagnostics of CHS. We also summarized the most frequently mutated genes and genome regions with altered pathways involved in the pathology of this tumor. Subsequently, we discussed imaging methods and the role of currently used therapies, including surgery and the limitations of chemo and radiotherapy. Finally, in this review, we presented novel targeted therapies, including those at ongoing clinical trials, which can be a potential future target in designing new therapeutics for patients with CHS.

Basic fibroblast growth factor promotes doxorubicin resistance in chondrosarcoma cells by affecting XRCC5 expression

Chondrosarcoma is the second most common form of bone cancer and is characterized by its ability to produce an extracellular matrix of the cartilage. High-grade chondrosarcoma is highly aggressive and can metastasize to other parts of the body. Chondrosarcoma is resistant to both conventional chemotherapy and radiotherapy; hence, the current main treatment is still surgical resection. Doxorubicin (Dox) has been shown to significantly improve patient survival compared with untreated chondrosarcoma. However, for patients with metastasis, surgical resection alone can hardly treat them. In addition, drug resistance is one of the leading causes of death in patients with chondrosarcoma. Secreted proteins can mediate cell-cell interactions in the cancer microenvironment, which may be associated with the development of drug resistance. In the present study, chondrosarcoma cells were treated with Dox, the conditioned medium was then collected and changes in secreted proteins were analyzed using the antibody array. Results showed that the Dox-treated group had the highest secretion of basic fibroblast growth factor (bFGF), indicating the effect of bFGF on Dox sensitivity in chondrosarcoma. Furthermore, lentiviral-mediated knockdown and treatment of exogenous recombinant protein were employed to further investigate the effect of bFGF on Dox resistance. Results demonstrated that bFGF can promote the expression of X-ray repair cross-complementing protein 5 (XRCC5), leading to Dox resistance. Secreted bFGF is likely to be detected in serum, in addition to being a biomarker for predicting Dox resistance, the combination of Dox and bFGF/XRCC5 blockers may be a new therapeutic strategy to improve the efficacy of Dox in future.

Results of a prospective phase 2 study of pazopanib in patients with surgically unresectable or metastatic chondrosarcoma

BACKGROUND

This single-arm, multicenter, phase 2 study evaluated the safety and antitumor activity of pazopanib in patients with unresectable or metastatic conventional chondrosarcoma.

METHODS

Eligible patients had conventional chondrosarcoma of any grade with measurable tumors that were unresectable or metastatic. Patients with mesenchymal, dedifferentiated, and extraskeletal myxoid chondrosarcoma subtypes and patients who received prior tyrosine kinase inhibitor therapy were excluded. Pazopanib at 800 mg once daily was administered for 28-day cycles. Tumor responses were evaluated by local radiology assessments every 2 cycles. The primary endpoint was the disease control rate (DCR) at week 16 (4 cycles).

RESULTS

Forty-seven patients were enrolled. The DCR at 16 weeks was 43% (95% confidence interval [CI], 28%-58%), which was superior to the null hypothesis rate of 30%, but the 2-sided P value (exact test) was .09 (1-sided P = .045). One patient had a partial response. The median overall survival was 17.6 months (95% CI, 11.3-35.0 months), and the median progression-free survival was 7.9 months (95% CI, 3.7-12.6 months). Grade 3 or higher adverse events were infrequent; hypertension (26%) and elevated alanine aminotransferase (9%) were most common.

CONCLUSIONS

This study provides evidence of positive drug activity for pazopanib in conventional chondrosarcoma.

Clinical Benefit of Pazopanib in a Patient with Metastatic Chondrosarcoma: A Case Report and Review of the Literature

Chondrosarcoma is a rare malignancy characterized by the production of cartilage matrix, displaying heterogeneous histopathology and clinical behavior. Due to lack of effective treatment for advanced disease, the clinical management of metastatic chondrosarcoma is exceptionally challenging. Chondrosarcomas harbor molecular abnormalities, such as overexpression of platelet-derived growth factor receptor (PDGFR)-alpha and PDGFR-beta, which are required for cancer development, progression, and metastasis. Pazopanib is a potent and selective multitargeted tyrosine kinase inhibitor, which co-inhibits stem cell growth factor receptor (c-KIT), fibroblast growth factor receptor (FGFR), PDGFR, and vascular endothelial growth factor receptor (VEGFR) and has demonstrated clinical activity in patients with advanced previously treated soft tissue sarcoma. Herein, we describe the unique case of a patient with metastatic chondrosarcoma who derived clinical benefit from pazopanib after first-line chemotherapy failure.

Hyaluronan stimulates chondrogenic gene expression in human meniscus cells

Purpose/Aim of the Study: Inner meniscus cells have a chondrocytic phenotype, whereas outer meniscus cells have a fibroblastic phenotype. In this study, we examined the effect of hyaluronan on chondrocytic gene expression in human meniscus cells.

MATERIALS AND METHODS

Human meniscus cells were prepared from macroscopically intact lateral meniscus. Inner and outer meniscus cells were obtained from the inner and outer halves of the meniscus. The cells were stimulated with hyaluronan diluted in Dulbecco's modified Eagle's medium without serum to the desired concentration (0, 10, 100, and 1000 μg/mL) for 2-7 days. Cellular proliferation, migration, and polymerase chain reaction analyses were performed for the inner and outer cells separately. Meniscal samples perforated by a 2 mm diameter punch were maintained for 3 weeks in hyaluronan-supplemented medium and evaluated by histological analyses.

RESULTS

Hyaluronan increased the proliferation and migration of both meniscus cell types. Moreover, cellular counts at the surface of both meniscal tissue perforations were increased by hyaluronan treatments. In addition, hyaluronan stimulated α1(II) collagen expression in inner meniscus cells. Accumulation of type II collagen at the perforated surface of both meniscal samples was induced by hyaluronan treatment. Hyaluronan did not induce type I collagen accumulation around the injured site of the meniscus.

CONCLUSION

Hyaluronan stimulated the proliferation and migration of meniscus cells. Our results suggest that hyaluronan may promote the healing potential of meniscus cells in damaged meniscal tissues.

Clinical benefit of antiangiogenic therapy in advanced and metastatic chondrosarcoma

Chondrosarcoma is the most common bone sarcoma in adults. Conventional chondrosarcoma, the commonest histological subtype, is largely resistant to anthracycline-based chemotherapy. There have been anecdotal reports of durable clinical benefit with antiangiogenic agents in this disease. A retrospective search of patients treated at three sarcoma referral centers was performed to identify patients with advanced chondrosarcoma treated with antiangiogenic agents. The aim of this study was to evaluate the efficacy and safety of antiangiogenic agents in advanced chondrosarcoma. Ten patients were identified; seven with conventional, one each with clear cell, extraskeletal mesenchymal chondrosarcoma and extraskeletal myxoid chondrosarcoma. The median progression-free survival for patients with conventional and clear cell sarcoma was 22.6 months. Median overall survival has not been met. Antiangiogenic therapy was well tolerated in this series of patients. Our retrospective data suggest that antiangiogenic therapy can provide prolonged clinical benefit in advanced chondrosarcoma patients. Further prospective trials are required to precisely define the role of this class of agent in advanced chondrosarcoma.

The distribution of vascular endothelial growth factor in human meniscus and a meniscal injury model

BACKGROUND

The meniscus plays an important role in controlling the complex biomechanics of the knee. Meniscus injury is common in the knee joint. The perimeniscal capillary plexus supplies the outer meniscus, whereas the inner meniscus is composed of avascular tissue. Angiogenesis factors, such as vascular endothelial growth factor (VEGF), have important roles in promoting vascularization of various tissues. VEGF-mediated neovascularization is beneficial to the healing of injured tissues. However, the distribution and angiogenic role of VEGF remains unclear in the meniscus and injured meniscus. We hypothesized that VEGF could affect meniscus cells and modulate the meniscus healing process.

METHODS

Menisci were obtained from total knee arthroplasty patients. Meniscal injury was created ex vivo by a microsurgical blade. VEGF mRNA and protein expression were detected by the polymerase chain reaction and immunohistochemical analyses, respectively.

RESULTS

In native meniscal tissue, the expression of VEGF and HIF-1α mRNAs could not be detected. However, VEGF and HIF-1α mRNAs were found in cultured meniscal cells (VEGF: outer > inner; HIF-1α: outer = inner). Injury increased mRNA levels of both VEGF and HIF-1α, with the increase being greatest in the outer area. Immunohistochemical analyses revealed that VEGF protein was detected mainly in the outer region and around injured areas of the meniscus. However, VEGF concentrations were similar between inner and outer menisci-derived media.

CONCLUSIONS

This study demonstrated that both the inner and outer regions of the meniscus contained VEGF. HIF-1α expression and VEGF deposition were high in injured meniscal tissue. Our results suggest that injury stimulates the expression of HIF-1α and VEGF that may be preserved in the extracellular matrix as the healing stimulator of damaged meniscus, especially in the outer meniscus.

Histological and biological comparisons between complete and incomplete discoid lateral meniscus

The discoid lateral meniscus (DLM) is an anatomically abnormal meniscus that covers a greater area of the tibial plateau than the normal meniscus. The DLM is classified into two types: complete (CDLM) and incomplete (ICDLM) types. In this study, we investigated the histological and cell biological characteristics of CDLM and ICDLM. The number of blood vessels, proteoglycan deposition, and collagen distribution were assessed using meniscal tissues. Collagen production was also investigated in CDLM and ICDLM cells. The intercondylar region of the CDLM had a higher number of blood vessels than the inner region of the ICDLM. Safranin O staining density and type II collagen deposition in ICDLM were higher than those in CDLM. Type II collagen-positive cells were higher in ICLDM than in CDLM. CDLM cells showed slender fibroblastic morphology, while ICDLM cells were triangular chondrocytic in shape. This study demonstrated that the intercondylar region of the CDLM showed similar properties to the outer region of the meniscus. The inner region of the ICDLM, on the other hand, differed from the intercondylar region of the CDLM. Our results suggest that the intercondylar region of the CDLM may have a high healing potential like the outer meniscus.

Anti-angiogenic therapy, a new player in the field of sarcoma treatment

Sarcomas encompass a heterogeneous family of mesenchymal malignancies. In metastatic disease improvement in outcome has been limited and there is a clear need for the development of new therapies. One potential target is angiogenesis, already an accepted target for treatment of more prevalent cancers. Multiple (pre)clinical studies focused on the role of angiogenesis and anti-angiogenic treatment in sarcomas. However, getting significant results is complicated due to the relatively small number of patients and the broad range of sarcoma subtypes. Recently, pazopanib has been approved for the treatment of advanced soft tissue sarcoma patients, which is an important step forward and paves the way for the introduction of anti-angiogenic treatment in sarcomas. However, more studies are needed to understand the biological mechanisms by which patients respond to angiogenic inhibitors and to detect markers of response. This review covers the knowledge that has been gained on the role of angiogenesis and anti-angiogenic therapy in sarcomas.

Chondromodulin-I derived from the inner meniscus prevents endothelial cell proliferation

The meniscus is a fibrocartilaginous tissue that plays an important role in controlling complex biomechanics of the knee. A perimeniscal capillary plexus supplies the outer meniscus, whereas the inner meniscus is composed of avascular tissue. Anti-angiogenic molecules, such as chondromodulin-I (ChM-I) and endostatin, have pivotal roles in preserving the avascularity of cartilage. However, the anti-angiogenic role of ChM-I is unclear in the meniscus. We hypothesized that the inner meniscus might maintain its avascular feature by expressing ChM-I. Immunohistochemical analyses revealed that ChM-I was mainly detected in the inner and superficial zones of the meniscus. On the other hand, endostatin distribution was similar between the inner and outer meniscus. In Western blot, ChM-I was detected only in the inner meniscus, whereas endostatin was equally observed in both inner and outer menisci. In addition, ChM-I concentration of the inner meniscus-derived conditioned medium was higher than that of the outer meniscus-derived medium. ChM-I removal from the inner meniscus-derived medium and functional blocking of ChM-I significantly increased endothelial cell proliferation. In this study, we demonstrated that the inner meniscus contained larger amounts of ChM-I, and that the inner meniscus-derived ChM-I inhibited endothelial cell proliferation. Our results suggest that ChM-I may be a key anti-angiogenic factor for maintaining the avascularity of the inner meniscus.

Mechanical stretch increases Smad3-dependent CCN2 expression in inner meniscus cells

The intrinsic zone-specific properties of the menisci are determined by biomechanical environments. In this study, we examined mechanical stretch-dependent expression of multifunctional growth factor CYR61/CTGF/NOV (CCN) 2, and investigated the role of CCN2 in meniscus cells. Uni-axial cyclic tensile strain (CTS) was applied using a STB-140 system. CTS-induced expression of CCN2 and α1(I) collagen (COL1A1) was assessed by quantitative real-time PCR analysis. The distribution of CCN2 and Smad2/3 in stretched cells was investigated by immunohistochemical analysis. Smad2/3-dependent CCN2 transactivation was measured by luciferase reporter assay. The relationship between Smad2/3 and CTS-induced CCN2 transcription was investigated by chromatin immunoprecipitation. CTS stimulated gene expression of CCN2 and COL1A1 in inner meniscus cells, but not in outer meniscus cells. Recombinant CCN2 increased COL1A1 expression only in inner meniscus cells. CCN2 synthesis and nuclear translocalization of phosphorylated Smad2/3 in inner meniscus cells were stimulated by CTS. The CCN2 promoter activity was synergistically enhanced by overexpressed Smad3 in stretched inner meniscus cells, but was not by Smad2. Chromatin immunoprecipitation revealed that CTS increased the association between Smad3 and the Smad-binding element on the CCN2 proximal promoter in inner meniscus cells. Our results suggest that stretch-induced CCN2 may have a crucial role in regulating COL1A1 expression in the inner meniscus.

Synthetic disulfide-bridged cyclic peptides mimic the anti-angiogenic actions of chondromodulin-I

Chondromodulin-I (ChM-I) is a 25-kDa glycoprotein in cartilage matrix that inhibits angiogenesis. It contains two distinctive structural domains: the N-terminal third of the molecule is a hydrophilic domain that contains O-linked and N-linked oligosaccharide chains, and the C-terminal two-thirds is a hydrophobic domain that contains all of the cysteine residues. In the present study, we have attempted to further uncover the structural requirements for ChM-I to exert anti-angiogenic activity by monitoring its inhibition of the vascular endothelial growth factor (VEGF)-A-induced migration of HUVEC in vitro. Site-directed mutagenesis experiments revealed that the cyclic structure formed by the disulfide bridge between Cys⁸³ and Cys⁹⁹ in human ChM-I is indispensable for its anti-angiogenic function. Moreover, the C-terminal hydrophobic tail (from Trp¹¹¹ to Val¹²⁰) was found to play an important role in ensuring the effectiveness of ChM-I activity on HUVEC. A synthetic cyclic peptide corresponding to the ChM-I region between Ile⁸² to Arg¹⁰⁰ also inhibited the migration of HUVEC, while replacing the Cys⁸³ and Cys⁹⁹ residues in this peptide with Ser completely negated this inhibitory activity. An additional synthetic cyclic peptide harboring the hydrophobic C-terminal tail of ChM-I clearly mimicked the inhibitory action of this protein on the migration of HUVEC and successfully inhibited tumor angiogenesis and growth in a xenograft mouse model of human chondrosarcoma.

Mechanical stretch enhances COL2A1 expression on chromatin by inducing SOX9 nuclear translocalization in inner meniscus cells

The meniscus plays an important role in controlling the biomechanics of the knee. However, the mechanical stress-related response in meniscus cells remains unclear. We investigated mechanical stretch-regulated gene expression in human meniscus cells. Human inner and outer meniscus cells were prepared from the inner and outer halves of the lateral meniscus. The gene expressions of Sry-type HMG box (SOX) 9 and α1(II) collagen (COL2A1) were assessed by real-time PCR analyses after cyclic tensile strain (CTS) treatment (0.5 Hz, 5% stretch). The localization and phosphorylation of SOX9 were evaluated by immunohistochemical and Western blot (WB) analyses. Chromatin immunoprecipitation (IP) analysis was performed to assess the stretch-related protein-DNA complex formation between SOX9 and the COL2A1 enhancer on chromatin. Type II collagen deposition and SOX9 production were detected only in inner menisci. CTS treatments increased expression of the COL2A1 and SOX9 genes in inner meniscus cells, but not in outer meniscus cells. In addition, CTS treatments stimulated nuclear translocalization and phosphorylation of SOX9 in inner meniscus cells. Chromatin IP analyses revealed that CTS increased the association between SOX9 and its DNA-binding site, included in the COL2A1 enhancer, on chromatin. Our results indicate that inner and outer meniscus cells have different properties in mechanical stretch-induced COL2A1 expression. In inner meniscus cells, mechanical stretch may have an essential role in the epigenetic regulation of COL2A1 expression.

Chondrosarcoma and peroxisome proliferator-activated receptor

Induction of differentiation and apoptosis in cancer cells by ligands of PPARγ is a novel therapeutic approach to malignant tumors. Chondrosarcoma (malignant cartilage tumor) and OUMS-27 cells (cell line established from grade III human chondrosarcoma) express PPARγ. PPARγ ligands inhibited cell proliferation in a dose-dependent manner, and induced apoptosis of OUMS-27. The higher-grade chondrosarcoma expressed a higher amount of antiapoptotic Bcl-xL in vivo. The treatment of OUMS-27 by 15d-PGJ₂, the most potent endogenous ligand for PPARγ, downregulated expression of Bcl-xL and induced transient upregulation of proapoptotic Bax, which could accelerate cytochrome c release from mitochondria to the cytosol, followed by induction of caspase-dependent apoptosis. 15d-PGJ₂ induced the expression of CDK inhibitor p21 protein in human chondrosarcoma cells, which appears to be involved in the mechanism of inhibition of cell proliferation. These findings suggest that targeted therapy with PPARγ ligands could be a novel strategy against chondrosarcoma.

The Bone Niche of Chondrosarcoma: A Sanctuary for Drug Resistance, Tumour Growth and also a Source of New Therapeutic Targets

Chondrosarcomas are malignant cartilage-forming tumours representing around 20% of malignant primary tumours of bone and affect mainly adults in the third to sixth decade of life. Unfortunately, the molecular pathways controlling the genesis and the growth of chondrosarcoma cells are still not fully defined. It is well admitted that the invasion of bone by tumour cells affects the balance between early bone resorption and formation and induces an “inflammatory-like” environment which establishes a dialogue between tumour cells and their environment. The bone tumour microenvironment is then described as a sanctuary that contributes to the drug resistance patterns and may control at least in part the tumour growth. The concept of “niche” defined as a specialized microenvironment that can promote the emergence of tumour stem cells and provide all the required factors for their development recently emerges in the literature. The present paper aims to summarize the main evidence sustaining the existence of a specific bone niche in the pathogenesis of chondrosarcomas.

Inner meniscus cells maintain higher chondrogenic phenotype compared with outer meniscus cells

Meniscus cells have several distinct properties in cellular morphology and extracellular matrix production. Inner meniscus cells are considered to have more chondrocytic phenotype compared with outer meniscus cells. However, the chondrogenic property of each meniscus cell has not been elucidated in detail. In this study, we investigated the difference between human inner and outer meniscus-derived cells in extracellular matrix deposition and chondrogenic potential. Monolayer-cultured inner meniscus cells showed small and ovoid shapes though slender and fibroblastic cells were obtained from outer half of human meniscus. The syntheses of type II collagen and safranin O-stained proteoglycans were increased in chondrogenic pellets derived from inner meniscus cells, rather than in outer meniscus cell-derived pellets. On the other hand, adipogenic lipid vacuoles were equally accumulated in both inner and outer meniscus cells after adipogenic treatment. Chondrogenic treatments also enhanced the expression of chondrogenic marker genes, such as Sry-type HMG box (SOX) 9, Scleraxis, and alpha1(II) collagen, in inner meniscus cells. However, SOX9 expression was not increased in outer meniscus cells even after chondrogenic treatment. This study demonstrated that inner meniscus cells maintained higher chondrogenic potential compared with outer meniscus cells. Our results suggest that the difference between inner and outer meniscus cells in chondrogenic property might have an essential role in preserving a zone-specific meniscal feature.

Analysis of angiogenic factors and cyclooxygenase-2 expression in cartilaginous tumors- clinical and histological correlation

OBJECTIVES

To study the role of angiogenesis and cyclooxygenase-2 expression in cartilaginous tumors and correlate these factors with prognosis.

INTRODUCTION

For chondrosarcoma, the histological grade is the current standard for predicting tumor outcome. However, a low-grade chondrosarcoma can follow an aggressive course-as monitored by sequential imaging techniques-even when it is histologically indistinguishable from an enchondroma. Therefore, additional tools are needed to help identify the biological potential of these tumors. The degree of angiogenesis that is induced by the tumor could assist in this task. Angiogenesis can be quantified by measuring the expression of vascular endothelial growth factor and CD34, and cyclooxygenase-2 can induce angiogenesis by stimulating the production of proangiogenic factors.

METHODS

In total, 21 enchondromas and 58 conventional chondrosarcomas were studied by examining the clinical and histopathological findings in conjunction with the immunostaining markers of angiogenesis and cyclooxygenase- 2 expression.

RESULTS

The significant variables that were associated with poor outcome were 1) higher-grade chondrosarcomas, 2) tumors that developed in flat bones, and 3) over-expression of CD34 (with a median count that was higher than 5.9 vessels in 5 high power fields). Moreover, CD34 expression (measured using the Chalkley method) revealed significantly higher microvessel density in flat bone chondrosarcomas.

DISCUSSION

Previous studies have shown a positive correlation between Chalkley microvessel density and histological grade; however, in our sample, we found that the former is predictive of the outcome. Chondrosarcomas in flat bones have been shown to correlate with a poor prognosis. We also found that CD34 microvessel density values were significantly higher in flat-bone chondrosarcomas. This could explain-at least in part-the more aggressive biological course that is taken by these tumors.

CONCLUSIONS

These results provide evidence that CD34 microvessel density in chondrosarcomas can be helpful in predicting patient outcome and may add to our understanding of chondrosarcoma pathogenesis.

Microenvironment alters epigenetic and gene expression profiles in Swarm rat chondrosarcoma tumors

BACKGROUND

Chondrosarcomas are malignant cartilage tumors that do not respond to traditional chemotherapy or radiation. The 5-year survival rate of histologic grade III chondrosarcoma is less than 30%. An animal model of chondrosarcoma has been established--namely, the Swarm Rat Chondrosarcoma (SRC)--and shown to resemble the human disease. Previous studies with this model revealed that tumor microenvironment could significantly influence chondrosarcoma malignancy.

METHODS

To examine the effect of the microenvironment, SRC tumors were initiated at different transplantation sites. Pyrosequencing assays were utilized to assess the DNA methylation of the tumors, and SAGE libraries were constructed and sequenced to determine the gene expression profiles of the tumors. Based on the gene expression analysis, subsequent functional assays were designed to determine the relevancy of the specific genes in the development and progression of the SRC.

RESULTS

The site of transplantation had a significant impact on the epigenetic and gene expression profiles of SRC tumors. Our analyses revealed that SRC tumors were hypomethylated compared to control tissue, and that tumors at each transplantation site had a unique expression profile. Subsequent functional analysis of differentially expressed genes, albeit preliminary, provided some insight into the role that thymosin-β4, c-fos, and CTGF may play in chondrosarcoma development and progression.

CONCLUSION

This report describes the first global molecular characterization of the SRC model, and it demonstrates that the tumor microenvironment can induce epigenetic alterations and changes in gene expression in the SRC tumors. We documented changes in gene expression that accompany changes in tumor phenotype, and these gene expression changes provide insight into the pathways that may play a role in the development and progression of chondrosarcoma. Furthermore, specific functional analysis indicates that thymosin-β4 may have a role in chondrosarcoma metastasis.

Nitric oxide synthases, cyclooxygenase-2, nitrotyrosine, and angiogenesis in chondrosarcoma and their relation to prognosis

BACKGROUND

The localization in tumor tissue of various markers by immunohistochemistry can help to establish a diagnosis or predict prognosis. Nitric oxide is associated with tumors and has been studied indirectly by nitrotyrosine analysis and with use of the enzymes nitric oxide synthase (NOS)1, NOS2, and NOS3. Nitric oxide reacts with superoxide anions to yield peroxynitrite, which has toxic effects on genes. Peroxynitrite adds a nitro group to the benzene ring of tyrosine to form nitrotyrosine. The accumulation of nitrotyrosine, a stable product in cells, indicates the formation of peroxynitrite. Nitric oxide stimulates the production of cyclooxygenase-2 (COX-2), which has been associated with angiogenesis in tumors. Neovascularization influences tumor prognosis, as demonstrated by microvessel studies with use of CD34, an immunohistochemical endothelial cell marker. This study examines the expression of these markers in chondrosarcomas and their relation to histological grade and prognosis.

METHODS

Tissue microarrays composed of formalin-fixed tissue samples from 101 patients with chondrosarcoma were immunohistochemically stained to localize NOS1, NOS2, NOS3, COX-2, nitrotyrosine, and CD34. Five samples of normal cartilage were used as controls. Patient demographics, selected surgical variables, and tumor grade were tabulated, and the associations were analyzed. Analyses of local and overall survival rates were performed with use of the Kaplan-Meier method, and multivariable analyses were performed.

RESULTS

There was a significant association of nitrotyrosine, COX-2, and CD34 with histological grades (p = 0.022, p = 0.014, and p = 0.028, respectively), but not with overall prognosis (p = 0.064, p = 0.143, and p = 0.581, respectively). The presence of NOS2 was associated with a lower rate of local disease-free survival (p = 0.038), and positive expressions of NOS1 and NOS2 were associated with decreased overall survival rates (p = 0.007 and p < 0.001, respectively). On multivariable analysis, NOS2 expression demonstrated an independent prognostic impact on local disease-free survival; NOS1 and NOS2 expression was a dependent variable, and their isolated or combined expression was related to lower overall survival rates (p = 0.046 and p = 0.004) (hazard ratio, 3.17 [95% confidence interval, 1.0 to 9.8] and 5.58 [95% confidence interval, 1.7 to 18.0], respectively).

CONCLUSIONS

Immunohistochemical markers may have an independent value in predicting the prognosis for patients with chondrosarcoma.

GDF-5/7 and bFGF activate integrin alpha2-mediated cellular migration in rabbit ligament fibroblasts

Cellular activities responding to growth factors are important in ligament healing. The anterior cruciate ligament (ACL) has poor healing potential compared to the medial collateral ligament (MCL). To assess the differences, we investigated the proliferation, migration, adhesion, and matrix synthesis responding to growth factors in rabbit ACL and MCL fibroblasts. ACL cell proliferation to basic fibroblast growth factor (bFGF), bone morphogenetic protein-2, growth and differentiation factor (GDF)-5, and GDF-7 treatment was similar to that of MCL cells. GDF-5 enhanced Col1a1 expression in ACL and MCL fibroblasts up to 4.7- and 17-fold levels of control, respectively. MCL fibroblasts showed stronger migration activities in response to bFGF and GDF-5 than ACL cells. GDF-5/7 and bFGF also changed the stress fiber formation and cellular adhesion by modulating the distribution of integrin alpha2. Functional blocking analyses using anti-integrin alpha2 antibodies revealed that cellular migration responding to growth factors depended on the integrin alpha2-mediated adhesion on type I collagen. The expression of integrin alpha2 was also increased by growth factors in both cells. Our results demonstrate that GDF-5/7 and bFGF stimulate cellular migration by modulating integrin alpha2 expression and integrin alpha2-dependent adhesion, especially in MCL fibroblasts. These findings suggest that the different healing potential between ACL and MCL may be caused by different cellular behavior in the integrin alpha2-mediated cellular migration in response to growth factors.

Anterior cruciate ligament-derived cells have high chondrogenic potential

Anterior cruciate ligament (ACL)-derived cells have a character different from medial collateral ligament (MCL)-derived cells. However, the critical difference between ACL and MCL is still unclear in their healing potential and cellular response. The objective of this study was to investigate the mesenchymal differentiation property of each ligament-derived cell. Both ligament-derived cells differentiated into adipogenic, osteogenic, and chondrogenic lineages. In chondrogenesis, ACL-derived cells had the higher chondrogenic property than MCL-derived cells. The chondrogenic marker genes, Sox9 and alpha1(II) collagen (Col2a1), were induced faster in ACL-derived pellets than in MCL-derived pellets. Sox9 expression preceded the increase of Col2a1 in both pellet-cultured cells. However, the expression level of Sox9 and a ligament/tendon transcription factor Scleraxis did not parallel the increase of Col2a1 expression along with chondrogenic induction. The present study demonstrates that the balance between Sox9 and Scleraxis have an important role in the chondrogenic differentiation of ligament-derived cells.

Scleraxis and E47 cooperatively regulate the Sox9-dependent transcription

During musculoskeletal development, Sry-type HMG box 9 (Sox9) has a crucial role in mesenchymal condensation and chondrogenesis. On the other hand, a tissue-specific basic helix-loop-helix (bHLH) transcription factor Scleraxis (Scx) regulates the differentiation of tendon and ligament progenitors. Whereas these two transcription factors cooperatively participate in the determination of cellular lineages, the precise interaction between Sox9 and Scx remains unclear. We have previously demonstrated that the Sox9-dependent transcription is synergistically activated by several Sox9-associating molecules, such as p300 and Smad3, on chromatin. In this study, we investigated the function of Scx in the Sox9-dependent transcription. The expression of alpha1(II) collagen (Col2a1) gene was stimulated by an appropriate transduction of Sox9 and Scx. Scx and its partner E47, which dimerizes with other bHLH proteins, cooperatively enhanced the Sox9-dependent transcription in luciferase reporter assays. Coactivator p300 synergistically increased the activity of Sox9-regulated reporter gene, which contains promoter and enhancer regions of Col2a1, in the presence of Scx and E47. Immunoprecipitation analyses revealed that Scx and E47 formed a transcriptional complex with Sox9 and p300. Scx/E47 heterodimer also associated with a conserved E-box sequence (CAGGTG) in the Col2a1 promoter on chromatin. These findings suggest that Scx and E47 might modulate the primary chondrogenesis by associating with the Sox9-related transcriptional complex, and by binding to the conserved E-box on Col2a1 promoter.

Development of chondrosarcoma animal models for assessment of adjuvant therapy

Chondrosarcoma is a primary cancer of bone causing significant morbidity due to local recurrence and limited treatment options. Relatively few chondrosarcoma animal models have been developed, and the only orthotopic model is technically demanding and has limited clinical relevance. The aim of this review is to assess the features of current animal chondrosarcoma models for the purpose of developing new models in which to test adjuvant chondrosarcoma therapy. The available literature on this topic was identified using the PubMed database, and then analysed for relevance to the human chondrosarcoma disease and feasibility in testing new therapeutic agents. Animal-derived chondrosarcoma models comprise predominantly allograft tumour transplanted into the rat (Swarm rat chondrosarcoma) or the hamster. These types of models are less relevant to the human disease and have been more useful for evaluation of chondrosarcoma growth and histology than in developing novel therapeutic agents. The athymic nude mouse has enabled reliable human xenograft transplantation. A number of human chondrosarcoma cell lines have been successfully used to generate tumours in this species, including OUMS-27 and HCS-2/A. Although effective in demonstrating anti-tumour effects of a number of agents, the lack of a representative orthotopic model diminishes overall clinical relevance. More clinically relevant models of human chondrosarcoma progression are required either through transgenic mice or orthotopic human xenograft models.

Basic FGF augments hypoxia induced HIF-1-alpha expression and VEGF release in T47D breast cancer cells

AIM

Both hypoxia inducible factor 1 (HIF-1) and basic fibroblast growth factor (bFGF) play important roles in tumour angiogenesis. This study was designed to clarify the cooperative effect of these two mediators in induction of vascular endothelial cell growth factor (VEGF) release from breast cancer and probe possible mechanisms involved.

METHODS

Release of VEGF from a breast cancer cell line (T47D) was quantitated by enzyme linked immunosorbent assay (ELISA). Expression of HIF-1 and ERK was assayed using Western blotting. Transient transfection and dual luciferase reporter assay were used to study HIF-1 transactivity.

RESULTS

The data showed that hypoxia induced the expression of HIF-1alpha protein, the transactivity of HIF-1 and the release of VEGF. bFGF further augmented these hypoxic inductions. The PI3K pathway was required for these processes as demonstrated by application of PI3Kinase inhibitor (LY294002) or mutant construct transfections. In contrast, the MEK1 inhibitor PD98059 showed no effect on either activation of HIF-1 or VEGF release, which is in agreement with our finding that ERK1/2 was not activated by hypoxia. Under hypoxic conditions, bFGF activated the MEK1/ERK pathway. PD98059 blocked the activation of ERK1/2 and suppressed bFGF-induced HIF-1 transactivity, yet the protein expression of HIF-1alpha or VEGF release was not affected by PD98059.

CONCLUSION

bFGF augments hypoxia induced VEGF release mainly through the PI3K pathway and partly depending on HIF-1 activity. Elucidation of this mechanism may provide a new target for anti-angiogenesis in cancer therapy.

Diagnostic Relevance of the Immunohistochemical Detection of Growth Factors in Benign and Malignant Cartilaginous Tumors

The goal of this study was to evaluate the diagnostic relevance of the expression of growth factors in cartilaginous tumors and to investigate on the possible correlation with grade, local recurrence, metastatic potential, and survival. Expression of VEGF, PDGF, FGF1, TFGbeta2, TNFalpha, Ki-67, and p53 was analyzed in 21 cases of benign and malignant cartilaginous tumors using immunohistochemistry. Immunohistochemical staining was performed on sections from paraffin-embedded tissue. The correlation of these markers' expression and grading or clinical outcome was also evaluated. Immunohistochemistry revealed a high correlation between grading and VEGF-positive staining (P=0.001). In addition, a correlation with local recurrence was found in cases with a positive expression of Ki-67 (P=0.035), TGFbeta (P=0.007), PDGF (P=0.007), and p53 (P=0.0455), with a time-related association. These data suggest a progressive modification in the biologic behavior of malignant cartilaginous tumors. VEGF could be used as a marker in the preoperative surgical assessment of chondrosarcoma. New therapeutic strategies could be considered for VEGF-positive cases. Positive expression of TGFbeta and PDGF seems to be a predictor of clinical outcome.

The vascular-targeting fusion toxin VEGF121/rGel inhibits the growth of orthotopic human bladder carcinoma tumors

Vascular endothelial growth factor (VEGF) and its receptors (FLT-1 and KDR) are overexpressed by human bladder cancer cells and tumor endothelial cells, respectively. Strategies that target VEGF receptors hold promise as antiangiogenic therapeutic approaches to bladder cancer. A fusion protein of VEGF121 and the plant toxin gelonin (rGel) was constructed, expressed in bacteria, and purified to homogeneity. Cytotoxicity experiments of VEGF121/rGel on the highly metastatic 253J B-V human bladder cancer cell line demonstrated that the VEGF121/rGel does not specifically target these cells, whereas Western blot analysis showed no detectable expression of KDR. Treatment with VEGF121/rGel against orthotopically implanted 253J B-V xenografts in nude mice resulted in a significant suppression of bladder tumor growth (approximately 60% inhibition; P < .05) compared to controls. Immunohistochemistry studies of orthotopic 253J B-V tumors demonstrated that KDR is highly overexpressed in tumor vasculature. Immunofluorescence staining with antibodies to CD-31 (blood vessel endothelium) and rGel demonstrated a dramatic colocalization of the construct on tumor neovasculature. Treated tumors also displayed an increase in terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling staining compared to controls. Thus, VEGF121/rGel inhibits the growth of human bladder cancer by cytotoxic effects directed against the tumor vascular supply and has significant potential as a novel antiangiogenic therapeutic against human bladder cancer.

The MAPK-AP-1/-Runx2 signalling axes are implicated in chondrosarcoma pathobiology either independently or via up-regulation of VEGF

AIMS

To investigate whether and how the JNK/ERK-AP-1/-Runx2 signalling pathways and vascular endothelial growth factor (VEGF) are engaged in the pathogenesis of cartilaginous tumours. Chondrosarcoma is the third most common primary skeletal malignancy. Nevertheless, the molecular events underlying its pathogenesis remain elusive. JNK/ERK MAPKs and their downstream effectors, c-Jun and c-Fos (AP-1), are involved in chondroblastic differention/proliferation. These proteins interact with the Runx2 transcription factor, which is also implicated in chondroblast biology. VEGF, a key angiogenic factor, is up-regulated in human chondrosarcomas.

METHODS AND RESULTS

Normal cartilage and neoplastic cells from 45 chondrosarcomas and 21 enchondromas were investigated immunohistochemically. We evaluated the cellular levels of JNK2, p-JNK2 (phosphorylated/activated JNK2), its main substrate, c-Jun, pc-Jun (phosphorylated/activated c-Jun) and c-Fos. Moreover, the levels of p-ERK (phosphorylated/activated ERK), Runx2 and VEGF were assessed. Positive immunostaining for all proteins was observed in the majority of the examined chondrosarcomas and in a small fraction of enchondromas. The expression levels of all proteins were positively and significantly correlated with each other. These levels were substantially augmented in high-grade compared with low-grade chondrosarcomas and in low-grade tumours compared with benign enchondromas, implying a potential use as molecular markers for prediction of high-grade neoplasms.

CONCLUSIONS

The JNK/ERK-AP-1/-Runx2 signal transduction 'network' is associated with chondroblastic malignant transformation and chondrosarcoma development, either separately or through coordinated induction of VEGF.

Differential expression of VEGF-A and angiopoietins in cartilage tumors and regulation by interleukin-1β

BACKGROUND

Vascular endothelial growth factor (VEGF)-A and angiopoietin (Ang)-1 and Ang-2 are key factors in angiogenic signaling. In this study the expression of these factors was identified in cartilage tumors. As interleukin (IL)-1beta has been found to be an indispensable factor in angiogenic signaling, we further analyzed the effect of IL-1beta on the expression of VEGF-A, Ang-1, and Ang-2 using a previously established cell culture model.

METHODS

Surgical specimens of enchondromas, conventional chondrosarcomas, and dedifferentiated chondrosarcomas were obtained from 72 patients. VEGF-A, Ang-1, and Ang-2 mRNA expression was detected by conventional and quantitative reverse transcription polymerase chain reaction (PCR). VEGF-A expression was also detected by immunohistochemistry or Western blot.

RESULTS

Differential expression of VEGF-A, Ang-1, and Ang-2 was clearly demonstrated in cartilage tumors. VEGF-A expression was positively correlated with the tumor type. Higher VEGF-A expression levels were detected in conventional chondrosarcomas Grades II and III (using a 3-tier grading system) than in dedifferentiated chondrosarcomas (P < .05). A typical pattern of VEGF-A isoforms was identified, including VEGF(121), VEGF(145), VEGF(165), and VEGF(189). Ang-1 presented as a low-level transcript with slightly elevated levels in chondrosarcomas (P < .05). Highly variable Ang-2 expression levels were detected in solitary cases of conventional chondrosarcomas. IL-1beta regulated VEGF-A and Ang-1 expressions in a dose-dependent manner. Whereas low IL-1beta concentrations increased VEGF-A and Ang-1 transcription, high IL-1beta concentrations had the opposite effect. IL-1beta did not activate Ang-2 expression.

CONCLUSIONS

Angiogenic signaling in cartilage tumors is variable and at least partly regulable by IL-1beta. The findings are of therapeutic relevance, either as a desired effect or a side effect in medical treatment.

Chondromodulin-I and tenomodulin: a new class of tissue-specific angiogenesis inhibitors found in hypovascular connective tissues

In tissues and/or organs of mesenchymal origin, the vasculature is usually well developed. However, there are certain hypovascular tissues that exhibit powerful anti-angiogenic resistance, implying the presence of tissue-type specific inhibitors of angiogenesis. Hyaline cartilage is one example, and several anti-angiogenic factors have been purified from cartilage. We previously identified chondromodulin-I (ChM-I) as a tissue-specific inhibitor of angiogenesis in fetal bovine cartilage. ChM-I is specifically expressed in the avascular regions of the growth-plate and cartilaginous bone rudiments in embryos. Recently, we cloned a novel type II transmembrane protein, tenomodulin (TeM), having a domain homologous to ChM-I at its C-terminus. TeM turned out to be expressed specifically in other hypovascular structures in the mesenchyme, such as the epimysium, tendon, and ligaments. In this overview, we discuss the structural characteristics of this class of anti-angiogenic molecules and their pathophysiological role in the control of vascularity.

Sox9 and p300 cooperatively regulate chromatin-mediated transcription

Chromatin structure is a fundamental component of gene regulation, expression, and cellular differentiation. We have previously reported that the multifunctional coactivator p300 is a member of the Sox9 (Sry-type high mobility group box 9)-related transcriptional apparatus and activates Sox9-dependent transcription during chondrogenesis. However, the mechanism of synergy between Sox9 and p300 in chromatin-mediated transcription has not been elucidated. In the present study we investigated the activity of Sox9 and p300 on chromatinized templates in vitro. Recombinant Sox9 was shown to be associated with several transcriptional cofactors including p300. In vitro transcription assays revealed that p300 potentiated Sox9-dependent transcription on chromatinized DNA and, importantly, was associated with hyperacetylated histones. Consistent with these results, the histone deacetylase inhibitor trichostatin A stimulated the expression of Sox9-regulated cartilage matrix genes and induced histone acetylation around the enhancer region of the collagen alpha1 (II) gene in chondrocytes. These findings suggest that Sox9 interacts with chromatin and activates transcription via regulation of chromatin modification.

Chondrosarcoma, lupus anticoagulant and cerebral ischaemia

Chondrosarcoma is a malignant disease of cartilage. Systemic embolisation usually arises from cancerous invasion of pulmonary vessels or the left atrium but cerebral embolisation or ischaemia is rarely recognised. We report a man with left leg amputation for tibial myxoid chondrosarcoma who suffered multiple cerebral embolisms one year later. Cerebral angiography and aortogram did not reveal luminal stenosis and a cardiac survey was normal. Lupus anticoagulant (LAC) and a prolonged activated partial thromboplastin time were detected. A molecular mimicry between prothrombin and paracrine hormones may have accounted for his LAC. A procoagulant autoantibody reacting against metastatic cancer cells may contribute to cancerous thrombosis, such as in chondrosarcoma.

Smad3 Induces Chondrogenesis through the Activation of SOX9 via CREB-binding Protein/p300 Recruitment

The transcriptional activation by SRY-type high mobility group box 9 (SOX9) and the transforming growth factor beta (TGF-beta) signals are necessary for chondrogenic differentiation. We have previously shown that CREB-binding protein (CBP/p300) act as an important SOX9 co-activator during chondrogenesis. In the present study, we investigated the relationship between TGF-beta-dependent Smad2/3 signaling pathways and the SOX9-CBP/p300 transcriptional complex at the early stage of chondrogenesis. Overexpressed Smad3 strongly induced the primary chondrogenesis of human mesenchymal stem cells. In addition, Smad3 enhanced the transcriptional activity of SOX9 and the expression of alpha1(II) collagen gene (COL2A1), and small interference RNA against Smad3 (si-Smad3) inhibited them. We observed that Smad2/3 associated with Sox9 in a TGF-beta-dependent manner and formed the transcriptional complexes with SOX9 on the enhancer region of COL2A1. Interestingly, the association between Sox9 and CBP/p300 was increased by Smad3 overexpression and was suppressed by si-Smad3. Our findings indicate that Smad3 has a stronger potential to stimulate the SOX9-dependent transcriptional activity by modulating the interaction between SOX9 and CBP/p300, rather than Smad2. This study suggests that the Smad3 pathway presents a key role for the SOX9-dependent transcriptional activation in primary chondrogenesis.

Angiogenesis inhibitors localized in hypovascular mesenchymal tissues: chondromodulin-I and tenomodulin

The majority of mesenchymal tissues obtain their nutrients via a well-developed network of capillaries. Cartilage, however, is normally devoid of capillary networks and, with the exception of endochondral bone formation, is resistant to vascular invasion from surrounding tissues. However, because of its avascular nature, cartilage is widely regarded as an enriched source of endogenous angiogenesis inhibitors, and many previous attempts have been made to identify these factors. We have identified chondromodulin-I (ChM-I) as an angiogenesis inhibitor derived from extracts of fetal epiphyseal cartilage, based upon its growth inhibitory activity in vascular endothelial cells in vitro. In the musculoskeletal system, ChM-I is specifically expressed in the avascular zones of cartilage. Upon functional expression of human ChM-I precursor cDNA, the purified recombinant protein was found to block the growth of solid tumors by inhibiting angiogenesis. Recently, we also cloned a cDNA that encodes a novel type II transmembrane glycoprotein containing a cysteine rich C-terminal domain homologous to ChM-I. We termed this glycoprotein "tenomodulin" (TeM) after tendons that were found to be the predominant expression sites in addition to other dense connective tissues including ligaments and cornea. Subsequently, by employing an adenovirus-mediated expression system, we demonstrated that the ChM-I-like domain of TeM is both antiangiogenic and antitumorigenic. In this article, we summarize the structural characteristics and biological activities of these two antiangiogenic molecules.

Perlecan and tumor angiogenesis

Perlecan is a major heparan sulfate proteoglycan (HSPG) of basement membranes (BMs) and connective tissues. The core protein of perlecan is divided into five domains based on sequence homology to other known proteins. Commonly, the N-terminal domain I of mammalian perlecan is substituted with three HS chains that can bind a number of matrix molecules, cytokines, and growth factors. Perlecan is essential for metazoan life, as shown by genetic manipulations of nematodes, insects, and mice. There are also known human mutations that can be lethal. In vertebrates, new functions of perlecan emerged with the acquisition of a closed vascular system and skeletal connective tissues. Many of perlecan's functions may be related to the binding and presentation of growth factors to high-affinity tyrosine kinase (TK) receptors. Data are accumulating, as discussed here, that similar growth factor-mediated processes may have unwanted promoting effects on tumor cell proliferation and tumor angiogenesis. Understanding of these attributes at the molecular level may offer opportunities for therapeutic intervention.

Osteopontin overproduced by tumor cells acts as a potent angiogenic factor contributing to tumor growth

Angiogenesis, which is essential for tumor growth, is regulated by various angiogenic factors. Osteopontin (OPN) is expressed in various human tumors and is postulated to be involved in tumor progression. We have recently reported that culture medium with murine neuroblastoma C1300 cells transfected with OPN gene significantly stimulates human umbilical vein endothelial cell migration and induces neovascularization in mice by dorsal air sac assay. However, the effect of OPN on tumorigenesis as an angiogenic factor remains to be clarified. In this study, we injected the OPN-transfected C1300 cells and control cells into the nude mice subcutaneously. OPN-overexpressing C1300 cells significantly formed rapidly growing tumor as compared to the control cells in mice, although in vitro and in vivo cell growth rates were similar. In vivo tumorigenecity of these cells correlated with the amount of secreted OPN protein. In addition, neovascularization of OPN-transfected tumor was significantly increased in comparison with those of control cells by immunohistochemistry for CD31. In vitro chemoinvasiveness and gene expression of proteases including uPA, MMP2, 9, MT1-MMP, and cathepsin B, D, L, were not different between OPN-transfected and control cells determined with matrigel invasion assay and cDNA expression macroarray, respectively. Conclusively, these results strongly imply that OPN plays an important role in tumor growth through the enhancement of angiogenesis in vivo.

Anti-cancer effect of genistein in oral squamous cell carcinoma with respect to angiogenesis and in vitro invasion

Oral squamous cell carcinoma (OSCC) is one of the most common head and neck cancers. OSCC generally has a poor prognosis due to its tendency towards local invasion and subsequent metastasis, which is mediated by multiple proteolytic enzymes and angiogenesis. The purpose of this study was to evaluate the anti-cancer effects of genistein, a soybean product known to be an effective natural anti-angiogenic agent, with respect to tumor growth, angiogenesis and in vitro invasion in an OSCC model. Northern blot analysis for vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and matrix metalloproteinase-2 (MMP-2), in vitro invasion assay and gelatin zymography were carried out for HSC-3 cells treated with genistein (27.3 microg/ml). In the animal experiment, genistein (0.5 mg/kg) was injected into tumor (HSC-3)-bearing mice (male balb/c/nu). The tumor growth rate and metastasis to lymph node or lung were compared and the microvessel density (CD31) was subsequently analyzed by immunohistochemistry. The genistein-treated group showed a down-regulation in VEGF mRNA expression, but not in bFGF and MMP-2 mRNA expression. Genistein reduced in vitro invasion through the artificial basement membrane and gelatin zymography also showed a reduced gelatinolytic activity in the genistein-treated group. In the genistein-treated mice, a significantly lower CD31 immunoreactivity was found. However, the tumor growth and metastatic behavior in the experimental group and the control group were similar and there were no significant differences. These results suggest the possible use of genistein as an anti-cancer agent in oral squamous cell carcinoma. However, it appears from the present study that anti-angiogenic therapy consisting of a single application of genistein may not provide a satisfactory treatment for OSCC. As a result, further research is recommended to confirm that genistein may be employed as an adjunct treatment modality for OSCC.

Anticarcinogenic properties of a daidzein-rich fraction isolated from soybean

In a previous study, we demonstrated that the methanol extract of soybean powder contains an active component(s) that promotes the differentiation of HL-60 cells. Partial purification of the extract, using solvent fractionation and silica gel chromatography, produced an active fraction rich in daidzein. The daidzein-rich fraction (DRF) was evaluated for its cancer preventive potential by assessing its cytotoxic activity and effect on the expression of the transforming growth factor beta (TGF-beta) family of cytokines and their receptors. DRF appeared to exert cytotoxic activity via an apoptotic pathway as evaluated by a DNA fragmentation assay and caspase-3 induction. DRF also increased the expression of TGF-beta2, but had little effect on the expression of other members of the TGF-beta family of cytokines and their receptors, or on the expression of the vascular endothelial growth factor gene. In conclusion, the DRF isolated from the methanol extract of soybean may have the potential to prevent tumorigenesis and, therefore, deserves to undergo further evaluation of its active component(s) and in vivo evaluation for anticarcinogenic efficacy.