Correlation between the expression of vegf and survival in osteosarcoma

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.

Together Intra-Tumor Hypoxia and Macrophagic Immunity Are Driven Worst Outcome in Pediatric High-Grade Osteosarcomas

Simple Summary

Radiological and immunohistochemical data were correlated with the outcome in a retrospective monocentric cohort of 30 pediatric osteosarcomas (OTS). A necrotic volume of more than 50 cm³ at diagnosis was significantly linked to a worse overall survival (OS). Regarding immunohistochemical analyses, an overexpression of hypoxic markers, such as HIF-1α and anhydrase carbonic IX (CAIX), was significantly linked to a worse OS, while pS6-RP hyperexpression was correlated with a better survival. We also featured that CD68 positive cells, representative of macrophagic M1 polarization, were mostly associated with HIF-1α and CAIX hyperexpressions and that M2-like polarization, mostly related to CD163 positivity, was correlated to mTor activation. These findings, involving clinical, radiological and biology data, allowed us to hypothesize a dual signature association ready to use routinely in future protocols.

Abstract

Background: Osteosarcomas (OTS) represent the most common primary bone cancer diagnosed in adolescents and young adults. Despite remarkable advances, there are no objective molecular or imaging markers able to predict an OTS outcome at diagnosis. Focusing on biomarkers contributing broadly to treatment resistance, we examine the interplay between the tumor-associated macrophages and intra-tumor hypoxia. Methods: Radiological and immunohistochemical (IHC) data were correlated with the outcome in a retrospective and monocentric cohort of 30 pediatric OTS. We studied hypoxic (pS6, phospho-mTor, HIF-1α and carbonic anhydrase IX (CAIX)) and macrophagic (CD68 and CD163) biomarkers. Results: The imaging analyses were based on MRI manual volumetric measures on axial post-contrast T1 weighted images, where, for each tumor, we determined the necrotic volume and its ratio to the entire tumor volume. When they were above 50 cm³ and 20%, respectively, they correlated with a worse overall survival (p = 0.0072 and p = 0.0136, respectively) and event-free survival (p = 0.0059 and p = 0.0143, respectively). IHC assessments enable a significant statistical link between HIF-1α/CAIX hyper-expressions, CD68+ cells and a worse outcome, whereas activation of mTor pathway was linked to a better survival rate and CD163+ cells. Conclusions: This study evidenced the links between hypoxia and immunity in OTS, as their poor outcome may be related to a larger necrotic volume on diagnostic MRI and, in biopsies, to a specific IHC profile.

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.

Comparison of VEGF-A secretion from tumor cells under cellular stresses in conventional monolayer culture and microfluidic three-dimensional spheroid models

Vascular endothelial growth factor (VEGF) is a major cytokine in tumor biology affecting tumor survival, aggressiveness and pro-angiogenetic activities. In addition, cellular stresses often result in aggressive pro-angiogenetic behavior in tumors. For in vitro study, conventional monolayer cell culture has been broadly exploited; however, it often provides limited information due to its different microenvironment from that in vivo. Recently, three-dimensional (3D) cell spheroid culture provides in vivo-like microenvironments to study tumor biology and their survival mechanisms with better predictive power. In this work, vascular endothelial growth factor of type A (VEGF-A) secretion from osteosarcoma (MG-63) cells cultured using monolayer and 3D spheroid models under two stress conditions: nutrient deficiency (reduced serum culture) and hypoxia-inducible factor (HIF) inhibition (HIF inhibitor, YC-1) are characterized and systematically compared. In order to obtain ample sample size for consistent characterization of cellular responses from cancer spheroids under the stresses and compare the responses to those from the conventional monolayer model, a microfluidic spheroid formation and culture device is utilized in the experiments. In the analysis, cell viability is estimated from captured images, and quantification of VEGF-A secreted from the cells is achieved using enzyme-linked immunosorbent assay (ELISA). The experimental results show that the viabilities decrease when the cells face higher stress levels in both monolayer and 3D spheroid culture models; however, the VEGF-A secretion profiles between the cell culture models are different. The VEGF-A secretion decreases when the cells face higher stress conditions in the monolayer cell culture. In contrast, for the 3D spheroid culture, the VEGF-A concentration decreases for low stress levels but increases while the stress level is high. The VEGF-A regulation in the 3D models mimics in vivo cases of tumor survival and can provide insightful information to investigate tumor angiogenesis in vitro. The approach developed in this paper provides an efficient method to quantitatively and statistically study tumor growth kinetics and stress responses from highly uniform samples and it can also be applied to compare the underlying biomolecular mechanisms in monolayer and 3D spheroid culture models to elucidate the effects of microenvironments on cellular response in cancer research.

Posterior retroperitoneoscopic adrenalectomy for pediatric adrenal tumors

BACKGROUND/AIMS

Posterior retroperitoneoscoic adrenalectomy has been reported as an option for adrenal tumor resection but is not commonly performed in children owing to the extreme semikneeling position advocated to flatten the lumbar lordosis in order to achieve adequate retroperitoneal space. As children have smaller lordosis angles, flattening of the lordosis and creation of optimal retroperitoneal space may be achieved with less hip flexion. We used pediatric lumbar lordosis measurements to develop a modified prone jackknife position and report our experiences with this setup for posterior retroperitoneoscopic adrenalectomy for adrenal tumors.

METHODS

Lordosis angles were measured on sagittal computed tomography (CT) and magnetic resonance imaging (MRI) studies of patients with adrenal tumors and compared to normal references. The data were used to develop our modified prone jackknife position. Selected patients with adrenal tumors underwent posterior retroperitoneoscopic adrenalectomy in this position. Patient demographics, diagnoses, operative times, complications, postop analgesia requirements, and length of hospitalization were analyzed.

RESULTS

CT and MRI studies were analyzed for 20 patients with adrenal tumors diagnosed in our institution from 2012 to 2017; median lordosis angle was 27.84° (range: 15.50°-36.48°) - less than reference lordosis angles of respective age groups, and flexion angles of common operating tables. Five patients underwent retroperitoneoscopic adrenalectomy between June 2016 and June 2018. Histological diagnoses were neuroblastoma, adrenal hyperplasia, pheochromocytoma, and adrenal angiomatoid fibrous histiocytoma. Median age was 4 years [range: 1-11]. Median operating time was 137 min [range 111-181 min]. No conversions to open surgery were required. One patient had intraoperative bleeding from the adrenal vein. Only 1 patient required postoperative opioids for analgesia. Median length of hospitalization after surgery was 2 days (range: 2-3 days).

CONCLUSIONS

Pediatric patients can achieve flattening of lumbar lordosis with less extreme positioning. Posterior retroperitoneoscopic adrenalectomy in a modified prone jackknife position is a feasible operation for pediatric patients with small adrenal masses.

TYPE OF STUDY

Clinical research paper.

LEVEL OF EVIDENCE

Level III.

Caveolin-1 Expression Together with VEGF can be a Predictor for Lung Metastasis and Poor Prognosis in Osteosarcoma

Caveolin-1, the major protein component of caveolae, plays vital functions in tumorigenesis and metastasis. Previous evidence demonstrated the positive role of Caveolin-1 in the regulation of endothelial cell differentiation and the involvement of Caveolin-1 in vascular endothelial growth factor (VEGF) mediated angiogenesis. The correlation of Caveolin-1 expression and angiogenesis is not yet elucidated in osteosarcoma. This study aimed to investigate the expression levels of Caveolin-1 and VEGF in osteosarcoma and their associations with clinicopathological data. This study included 66 formalin-fixed and paraffin embedded osteosarcoma tissue samples. The expression levels of Caveolin-1 and VEGF were assessed by immunohistochemistry. Then associations with clinicopathological variables and the correlation between both markers were evaluated statistically. We also investigated the expression of Caveolin-1 and VEGF values in gene microarrays of osteosarcoma patients and cell lines by using GEO data sets on https://www.ncbi.nlm.nih.gov. Caveolin-1 and VEGF were expressed in 19.6% and 77.3%, respectively. Caveolin-1 expression was associated positively with osteoblastic histological subtype (P < 0.0001). VEGF expression showed positive association with patient age, histological grade and clinical stage (P = 0.031, P = 0.024 and P < 0.001; respectively). An inverse correlation between Caveolin-1 and VEGF expressions in osteosarcoma was found (r = 0.2 P = 0.04). In silico analysis of Caveolin-1 and VEGF expression supported our results. Our results suggest that Caveolin-1 may act as a tumor suppressor in osteosarcoma. Down-regulation of Caveolin-1 can be used as an indicator for poor prognosis in osteosarcoma patients. Meanwhile, overexpression of VEGF is a predictor of pulmonary metastasis and poor prognosis.

A humanized bone microenvironment uncovers HIF2 alpha as a latent marker for osteosarcoma

The quest for predictive tumor markers for osteosarcoma (OS) has not well progressed over the last two decades due to a lack of preclinical models. The aim of this study was to investigate if microenvironmental modifications in an original humanized in vivo model alter the expression of OS tumor markers. Human bone micro-chips and bone marrow, harvested during hip arthroplasty, were implanted at the flanks of NOD/scid mice. We administered recombinant human bone morphogenetic protein 7 (rhBMP-7) in human bone micro-chips/bone marrow group I in order to modulate bone matrix and bone marrow humanization. Ten weeks post-implantation, human Luc-SAOS-2 OS cells were injected into the humanized tissue-engineered bone organs (hTEBOs). Tumors were harvested 5 weeks post-implantation to determine the expression of the previously described OS markers ezrin, periostin, VEGF, HIF1α and HIF2α. Representation of these proteins was analyzed in two different OS patient cohorts. Ezrin was downregulated in OS in hTEBOs with rhBMP-7, whereas HIF2α was significantly upregulated in comparison to hTEBOs without rhBMP-7. The expression of periostin, VEGF and HIF1α did not differ significantly between both groups. HIF2α was consistently present in OS patients and dependent on tumor site and clinical stage. OS patients post-chemotherapy had suppressed levels of HIF2α. In conclusion, we demonstrated the overall expression of OS-related factors in a preclinical model, which is based on a humanized bone organ. Our preclinical research results and analysis of two comprehensive patient cohorts imply that HIF2α is a potential prognostic marker and/or therapeutic target. STATEMENT OF SIGNIFICANCE: This study demonstrates the clinical relevance of the humanized organ bone microenvironment in osteosarcoma research and validates the expression of tumor markers, especially HIF2α. The convergence of clinically proven bone engineering concepts for the development of humanized mice models is a new starting point for investigations of OS-related marker expression. The validation and first data set in such a model let one conclude that further clinical studies on the role of HIF2α as a prognostic marker and its potential as therapeutic target is a condition sine qua non.

Humanization of bone and bone marrow in an orthotopic site reveals new potential therapeutic targets in osteosarcoma

BACKGROUND

Existing preclinical murine models often fail to predict effects of anti-cancer drugs. In order to minimize interspecies-differences between murine hosts and human bone tumors of in vivo xenograft platforms, we tissue-engineered a novel orthotopic humanized bone model.

METHODS

Orthotopic humanized tissue engineered bone constructs (ohTEBC) were fabricated by 3D printing of medical-grade polycaprolactone scaffolds, which were seeded with human osteoblasts and embedded within polyethylene glycol-based hydrogels containing human umbilical vein endothelial cells (HUVECs). Constructs were then implanted at the femur of NOD-scid and NSG mice. NSG mice were then bone marrow transplanted with human CD34 ⁺ cells. Human osteosarcoma (OS) growth was induced within the ohTEBCs by direct injection of Luc-SAOS-2 cells. Tissues were harvested for bone matrix and marrow morphology analysis as well as tumor biology investigations. Tumor marker expression was analyzed in the humanized OS and correlated with the expression in 68 OS patients utilizing tissue micro arrays (TMA).

RESULTS

After harvesting the femurs micro computed tomography and immunohistochemical staining showed an organ, which had all features of human bone. Around the original mouse femur new bone trabeculae have formed surrounded by a bone cortex. Staining for human specific (hs) collagen type-I (hs Col-I) showed human extracellular bone matrix production. The presence of nuclei staining positive for human nuclear mitotic apparatus protein 1 (hs NuMa) proved the osteocytes residing within the bone matrix were of human origin. Flow cytometry verified the presence of human hematopoietic cells. After injection of Luc-SAOS-2 cells a primary tumor and lung metastasis developed. After euthanization histological analysis showed pathognomic features of osteoblastic OS. Furthermore, the tumor utilized the previously implanted HUVECS for angiogenesis. Tumor marker expression was similar to human patients. Moreover, the recently discovered musculoskeletal gene C12orf29 was expressed in the most common subtypes of OS patient samples.

CONCLUSION

OhTEBCs represent a suitable orthotopic microenvironment for humanized OS growth and offers a new translational direction, as the femur is the most common location of OS. The newly developed and validated preclinical model allows controlled and predictive marker studies of primary bone tumors and other bone malignancies.

A Validated Preclinical Animal Model for Primary Bone Tumor Research

BACKGROUND

Despite the introduction of 21st-century surgical and neoadjuvant treatment modalities, survival of patients with osteosarcoma (OS) has not improved in two decades. Advances will depend in part on the development of clinically relevant and reliable animal models. This report describes the engineering and validation of a humanized tissue-engineered bone organ (hTEBO) for preclinical research on primary bone tumors in order to minimize false-positive and false-negative results due to interspecies differences in current xenograft models.

METHODS

Pelvic bone and marrow fragments were harvested from patients during reaming of the acetabulum during hip arthroplasty. HTEBOs were engineered by embedding fragments in a fibrin matrix containing bone morphogenetic protein-7 (BMP-7) and implanted into NOD-scid mice. After 10 weeks of subcutaneous growth, one group of hTEBOs was harvested to analyze the degree of humanization. A second group was injected with human luciferase-labeled OS (Luc-SAOS-2) cells. Tumor growth was followed in vivo with bioluminescence imaging. After 5 weeks, the OS tumors were harvested and analyzed. They were also compared with tumors created via intratibial injection.

RESULTS

After 10 weeks of in vivo growth, a new bone organ containing human bone matrix as well as viable and functional human hematopoietic cells developed. Five weeks after injection of Luc-SAOS-2 cells into this humanized bone microenvironment, spontaneous metastatic spread to the lung was evident. Relevant prognostic markers such as vascular endothelial growth factor (VEGF) and periostin were found to be positive in OS tumors grown within the humanized microenvironment but not in tumors created in murine tibial bones. Hypoxia-inducible transcription factor-2α (HIF-2α) was detected only in the humanized OS.

CONCLUSIONS

We report an in vivo model that contains human bone matrix and marrow components in one organ. BMP-7 made it possible to maintain viable mesenchymal and hematopoietic stem cells and created a bone microenvironment mimicking human physiology.

CLINICAL RELEVANCE

This novel platform enables preclinical research on primary bone tumors in order to test new treatment options.

Silencing of VEGF inhibits human osteosarcoma angiogenesis and promotes cell apoptosis via VEGF/PI3K/AKT signaling pathway

BACKGROUND

Osteosarcoma is a kind of highly malignant tumor and the growth and metastasis is closely related to angiogenesis. Vascular endothelial growth factor (VEGF) is an important angiogenesis-promoting factor. In the current study, we investigated the effects of suppressed VEGF on osteosarcoma and its molecular mechanism provided for a basis by targeting angiogenesis.

MATERIAL/METHODS

We established bearing human osteosarcoma Wistar rats model by subcutaneous inoculation of human SaOS-2 cells and the adenovirus vector Ad-VEGF-siRNA was constructed for further study. We assessed the efficiency of VEGF silencing and its influence on SaOS-2 cells. The expression of mRNA and protein were detected by RT-PCR and western blotting, respectively. Intratumoral microvessel density (MVD), VEGF and CD31 were evaluated by immunohistochemistry. We detected the cell apoptotic rates by flow cytometry.

RESULTS

Our results indicated that Ad-VEGF-siRNA could effectively suppressed the expression of VEGF expression, inhibited the proliferation capability and promoted apoptosis of SaOS-2 cells in vitro. Silencing of VEGF expression also suppress osteosarcoma tumor growth and reduce osteosarcoma angiogenesis in the Wistar rats model in vivo. Furthermore, We found that phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT) activation were considerably reduced while inhibition VEGF expression in SaOS-2 cells.

CONCLUSION

Our data demonstrated that VEGF silencing could suppress cells proliferation, promote cells apoptosis and reduce osteosarcoma angiogenesis through inactivation of VEGF/PI3K/AKT signaling pathway.

Clinicopathological and prognostic significance of chemokine receptor CXCR4 in patients with bone and soft tissue sarcoma: a meta-analysis

The prognostic significance of CXC chemokine receptor 4 (CXCR4) in patients with bone and soft tissue sarcomas remains controversial. To investigate the impact of its expression on survival and clinicopathological features, we performed a meta-analysis. Comprehensive literature searches were conducted in PubMed, Web of Science, Embase and Cochrane Library for relevant studies. In total, 12 studies with 997 sarcoma patients were included. CXCR4 expression was found to be significantly associated with poor overall survival (HR 2.37, 95 % CI 1.86-3.01; P < 0.001). Further, when the analysis was stratified by histological subtypes (bony sarcoma including osteosarcoma and Ewing sarcoma and soft tissue sarcoma including synovial sarcoma and rhabdomyosarcoma), statistical analysis method (multivariate analysis and univariate analysis) and CXCR4 measuring method (IHC or RT-PCR), the significant correlation to poor overall survival was also observed except for that in Ewing sarcoma and RT-PCR groups. As for clinicopathological features, CXCR4 expression was significantly associated with higher rate of metastasis (OR 6.97, 95 % CI 2.28-21.31; P = 0.001) and higher tumor stage (OR 7.55, 95 % CI 1.25-45.47; P = 0.027), but not associated with gender, age and tumor site. In conclusion, CXCR4 expression may be an effective predictive factor of poor prognosis and clinicopathological features for bone and soft tissue sarcomas. Further studies are needed to validate our findings.

Effects of vascular endothelial growth factor expression on pathological characteristics and prognosis of osteosarcoma

Vascular endothelial growth factor (VEGF) has been linked with tumor invasion and metastasis. However, the role of VEGF expression in osteosarcoma remains controversial. By searching the PubMed, Embase, and Google Scholar databases, we conducted a meta-analysis to evaluate the pathological and prognostic significance of VEGF in osteosarcoma. Studies were pooled, and the odds ratio (OR) and its corresponding 95 % confidence interval (CI) were calculated. Nine relevant articles were included in this meta-analysis study. We performed pooled analysis with available data on the association between VEGF expression and age, gender, tumor stages IIB-III versus I-IIA, tumor recurrence, response to chemotherapy, and tumor metastasis. Our results revealed that VEGF expression might be closely associated with metastasis of osteosarcoma (OR 4.74, 95 % CI 2.53-8.87, P < 0.001). Furthermore, our findings also demonstrated that patients with grade IIB-III osteosarcoma showed a higher frequency of VEGF expression than those with grade I-IIA osteosarcoma (OR 5.33, 95 % CI 2.03-13.98, P = 0.001). We failed to find the association between VEGF expression and age (OR 0.82, 95 % CI 0.44-1.53, P = 0.539), gender (OR 1.33, 95 % CI 0.52-3.42, P = 0.553), tumor recurrence (OR 1.47, 95 % CI 0.56-3.86, P = 0.429), and response to chemotherapy (OR 1.26, 95 % CI 0.14-11.72, P = 0.839). In conclusion, VEGF is related to the grade and metastasis of osteosarcoma. It may play a significant role in clinical guidelines for the treatment and prognostic evaluation.

Promoter hypermethylation of the cysteine protease RECK may cause metastasis of osteosarcoma

The present study examined the role of reversion-inducing cysteine-rich protein with Kazal motifs (RECK) promoter hypermethylation as a causative factor in metastasis of osteosarcoma. Using human pathological samples, it is demonstrated that RECK, a cysteine protease that reversibly regulates expression of matrix metalloproteases like matrix metallopeptidase 9 (MMP9), is transcriptionally inhibited in osteosarcoma, especially metastatic variants. This result comes from its promoter hypermethylation, as evaluated in the present study by methylation-specific PCR reaction. The expression of RECK was also significantly diminished in the metastatic variants of osteosarcoma. This downregulation of RECK in advanced grades of osteosarcoma and metastatic grades was also associated with the increased expression of invadosome-specific markers like MMP9, phospho-FAK, and integrins, suggesting the complex contributions of RECK in the prevention of metastasis and its downregulation as a causative factor in osteosarcoma metastasis.

The early stages of tumor angiogenesis in human osteosarcoma: a nude mice xenotransplant model

Osteosarcoma (Os) is the most common malignant bone tumor in childhood and not rare in adults. In recent years, much research has focused on the role of angiogenesis in tumor development, growth, invasion, and metastasis. The aims of this study were to characterize neovascularization established between the xenotransplanted Os and the host at histological, immunohistochemical, ultrastructural, and molecular level, and to evaluate if this model could be used in testing new anti-angiogenic drugs. Three xenotransplanted human Os were evaluated. Tumor pieces 3-4 mm in size were implanted subcutaneously on the back of athymic Balb-c nude mice (n = 14). The animals were killed at 24, 48, and 72 h and 7, 14, 21, and 28 days after implantation. Tumor samples were either fixed in 10 % formaldehyde and embedded in paraffin for histological analysis, or fixed with glutaraldehyde (2 %) for electron microscopy or retained non-fixed for molecular analysis (ELISA and qRT-PCR). Morphologically, intense neo-vasculogenesis within tumor parenchyma was present between the first and third week after transplantation. Immunohistochemistry demonstrated overexpression of VEGF and their receptors together with PDFGFRA 24-48 h after tumor implantation. Additionally, neoplastic cells co-expressed chemokines (CXCL9, CXCL10, and GRO) and their receptors. Molecular studies showed two expression profiles, distinguishing an early and a late phase in the angiogenic process. In Os, our model showed two stages of induced angiogenesis, with close association between histological and molecular events. This approximation could be of use for testing the effect of different anti-angiogenic agents.