ETC-159, an Upstream Wnt inhibitor, Induces Tumour Necrosis via Modulation of Angiogenesis in Osteosarcoma.

There is an increasing urgency in the search for new drugs to target high-grade cancers such as osteosarcomas (OS), as these have limited therapeutic options and poor prognostic outlook. Even though key molecular events leading to tumorigenesis are not well understood, it is widely agreed that OS tumours are Wnt-driven. ETC-159, a PORCN inhibitor that inhibits the extracellular secretion of Wnt, has recently progressed on to clinical trials. In vitro and in vivo murine and chick chorioallantoic membrane xenograft models were established to examine the effect of ETC-159 on OS. Consistent with our hypothesis, we noted that ETC-159 treatment not only resulted in markedly decreased ß-catenin staining in xenografts, but also increased tumour necrosis and a significant reduction in vascularity-a hereby yet undescribed phenotype following ETC-159 treatment. Through further understanding the mechanism of this new window of vulnerability, therapies can be developed to potentiate and maximize the effectiveness of ETC-159, further increasing its clinical utility for the treatment of OS.

Tumor-associated macrophages in osteosarcoma.

Osteosarcoma (OS) is the most common primary bone tumor in children and adolescents. It is an aggressive tumor with a tendency to spread to the lung, which is the most common site of metastasis. Patients with advanced OS with metastases have poor prognoses despite the application of chemotherapy, thus highlighting the need for novel therapeutic targets. The tumor microenvironment (TME) of OS is confirmed to be essential for and supportive of tumor growth and dissemination. The immune component of the OS microenvironment is mainly composed of tumor-associated macrophages (TAMs). In OS, TAMs promote tumor growth and angiogenesis and upregulate the cancer stem cell-like phenotype. However, TAMs inhibit the metastasis of OS. Therefore, much attention has been paid to investigating the mechanism of TAMs in OS development and the progression of immunotherapy for OS. In this article, we aim to summarize the roles of TAMs in OS and the major findings on the application of TAMs in OS treatment.

Vascularized Bone Graft Reconstruction Following Bone Tumor Resection at a Multidisciplinary Sarcoma Center: Outcome Analysis.

BACKGROUND/AIM: Limb-sparing procedures are frequently applied to improve patient outcomes. The use of vascularized bone grafts is associated with significant improvements in oncologic safety and functional satisfaction. This study highlights the clinical outcomes following tumor resection combined with vascularized bone graft reconstructions. PATIENTS AND METHODS: Twenty-five free vascularized bone grafts (17 fibulas, 5 iliac crests, 3 medial femoral condyles) were assessed with respect to consolidation and hypertrophy, functional and oncologic outcomes, and local complications. RESULTS: The rate of healing of fibular grafts after a median of 5 months was 86%. The rate of achieved unions of iliac crest grafts after a median of 5 months was 80%. In medial femoral condyle bone grafts, union occurred after a median of 4 months. Significant hypertrophy was observed in 13 patients. We identified six complications with highest rates in the fibula-group. Despite the high complications, functional results were highly satisfactory. CONCLUSION: Vascularized bone grafts represent a reconstructive approach, maintaining long-term functionality and cosmetic satisfaction without compromising tumor recurrence outcomes.

Prostate cancer-derived MMP-3 controls intrinsic cell growth and extrinsic angiogenesis.

Bone metastatic prostate cancer significantly impacts patient quality of life and overall survival, and despite available therapies, it is presently incurable with an unmet need for improved treatment options. As mediators of tumor progression, matrix metalloproteinases (MMPs) can degrade extracellular matrix components and regulate growth factor and cytokine bioactivity. Depending on tissue context, MMPs can either promote or inhibit tumorigenesis. Therefore, it is essential to study individual MMPs in specific cancer contexts and microenvironments to support the design and application of selective MMP inhibitors. Here we report that tumor-derived MMP-3 contributes to bone metastatic prostate cancer progression via intrinsic and extrinsic routes. MMP-3 ablation in prostate cancer cell lines significantly reduced in vitro growth combined with lowered AKT and ERK phosphorylation and total VEGFR1 and FGFR3 protein levels. In vivo, MMP-3 ablated tumors grew at a slower rate and were significantly less vascularized. Quantitative PCR analyses of wild type and MMP-3 silenced prostate cancer cells also demonstrate downregulation of a wide array of angiogenic factors. The extrinsic role for MMP-3 in angiogenesis was supported by in vitro endothelial tube formation assays where the lack of MMP-3 in prostate cancer conditioned media resulted in slower rates of tube formation. Taken together, our results suggest that tumor-derived MMP-3 contributes to prostate cancer growth in bone. These data indicate that selective inhibition of MMP-3 and/or targeting MMP generated products could be efficacious for the treatment of prostate to bone metastases.

Switching Homes: How Cancer Moves to Bone.

Bone metastases (BM) are a very common complication of the most prevalent human cancers. BM are extremely painful and may be life-threatening when associated with hypercalcaemia. BM can lead to kidney failure and cardiac arrhythmias and arrest, but why and how do cancer cells decide to "switch homes" and move to bone? In this review, we will present what answers science has provided so far, with focus on the molecular mechanisms and cellular aspects of well-established findings, such as the concept of "vicious cycle" and "osteolytic" vs. "osteosclerotic" bone metastases; as well as on novel concepts, such as cellular dormancy and extracellular vesicles. At the molecular level, we will focus on hypoxia-associated factors and angiogenesis, the Wnt pathway, parathyroid hormone-related peptide (PTHrP) and chemokines. At the supramolecular/cellular level, we will discuss tumour dormancy, id est the mechanisms through which a small contingent of tumour cells coming from the primary site may be kept dormant in the endosteal niche for many years. Finally, we will present a potential role for the multimolecular mediators known as extracellular vesicles in determining bone-tropism and establishing a premetastatic niche by influencing the bone microenvironment.

Melatonin regulates tumor angiogenesis via miR-424-5p/VEGFA signaling pathway in osteosarcoma.

Melatonin is recognized as an anti-angiogenic agent, but its function in the tumor microenvironment especially in osteosarcoma remains uncertain. Among the selected miRNAs, miR-205, miR-424, miR-140, miR-106, and miR-519 were upregulated by melatonin in osteosarcoma cells. The functional role of miR-424-5p in osteosarcoma was further analyzed using miR-424-5p mimic/inhibitor. VEGFA mRNA and protein expression were altered by miR-424-5p mimic/inhibitor transfection with and without melatonin treatment and it was further identified that the VEGFA 3'UTR is directly targeted by miR-424-5p using the luciferase reporter gene system. The conditioned medium from SaOS2 and MG63 cells treated with melatonin and/or transfected with miR-424-5p mimic/inhibitor was exposed to endothelial cells, and cell proliferation and migration was analyzed. MG-63 and SaOS2 cells are also transfected with miR-424-5p inhibitors and positioned on CAM vascular bed to study the angiogenic activity at both morphological and molecular level under melatonin treatment. Our observations demonstrate for the first time that, melatonin upregulated the expression of miR-424-5p in osteosarcoma inhibiting VEGFA. Furthermore, it suppresses tumor angiogenesis, modulating surrounding endothelial cell proliferation and migration as well as the morphology of blood vessels, and angiogenic growth factors. These findings suggest that melatonin could play a pivotal role in tumor suppression via miR-424-5p/VEGFA axis.

Emergency Surgery in High Volume Osteosarcoma of Left Proximal Humerus Due to Vascular Compromise: A Case Report.

BACKGROUND Osteosarcoma is the most common type of malignant bone tumor arising from mesenchymal stem cell. When occurring on the proximal humerus, it is associated with poor outcomes; there are numerous neurovascular structures around proximal humerus. Unfortunately, the degree of vascular involvement in osteosarcoma is rarely evaluated and reported. Thus, we would like to highlight our case. CASE REPORT We reported a case of left proximal humerus osteosarcoma causing dead limb in a 14-year-old boy. The dead limb progressed in the span of 3 weeks. An emergency forequarter amputation (FQA) was conducted to prevent further complications such as septicemia and mortality. Two months after the surgery, the patient had improved quality of life. One year after, the patient had no local recurrence. However, there was a lung metastasis detected 9 months after the surgery. The patient died 13 months after the surgery. CONCLUSIONS Osteosarcoma of the proximal humerus can potentially compromise vascular structures. Early diagnosis and treatment are mandatory to prevent such complications.

Apatinib as targeted therapy for advanced bone and soft tissue sarcoma: a dilemma of reversing multidrug resistance while suffering drug resistance itself.

Bone and soft tissue sarcomas are rare malignant tumors originated from mesenchymal tissues. They harbor more than 50 distinct subtypes and differ in pathological features and clinical courses. Despite the significant improvements in modern multi-modality treatment, the outcomes and overall survival rates remain poor for patients with advanced, refractory, metastatic, or relapsed diseases. The growth and metastasis of bone and soft tissue sarcoma largely depend on angiogenesis, and VEGF/VEGFR pathway is considered as the most prominent player in angiogenesis. Therefore, blockade of VEGF/VEGFR pathways is a promising therapeutic strategy to retard neovascularization. Several VEGFR inhibitors have been developed and revealed their favorable anti-neoplastic effects in various cancers, but such desirable anti-tumor effects are not obtained in advanced sarcomas because of multiple reasons, such as drug tolerance, short duration of response, and severe adverse effects. Fortunately, preclinical and clinical studies have indicated that apatinib is a novel promising VEGFR2 inhibitor showing potent anti-angiogenic and anti-neoplastic activities in advanced sarcomas. Especially, apatinib has showed notable characteristics in multidrug resistance reversal, tumor regression, vascular normalization, immunosuppression alleviation, and enhancement of chemotherapeutic and radiotherapeutic effects. However, apatinib also gets struck in dilemma of reversing multidrug resistance of chemotherapeutic agents while suffering drug resistance itself, and several difficulties should be tackled before full use of apatinib. In this review, we discuss the outstanding characteristics and main predicaments of apatinib as targeted therapy in advanced sarcomas. Bone and soft tissue sarcomas are rare but malignant tumors originated from mesenchymal tissues. They harbor more than 100 distinct subtypes and differ in features of pathologies and clinical courses. Despite the significant improvements in modern multi-modality treatment, the outcomes and overall survival rates remain poor for patients with advanced, refractory, metastatic, or relapsed lesions. The growth and metastasis of bone and soft tissue sarcoma largely depend on angiogenesis and VEGF/VEGFR pathways play a pivotal role in angiogenesis. Therefore, blockade of VEGF/VEGFR pathways is a promising therapeutic strategy. Several VEGFR inhibitors have been developed and verified in clinical trials but with unfavorable outcomes. Fortunately, preclinical studies and clinical trials have indicated that apatinib is a novel promising VEGFR2 inhibitor showing potent anti-angiogenic and anti-neoplastic activities in advanced sarcomas. Actually, apatinib has showed notable characteristics in multidrug resistance reversal, tumor regression, vascular normalization, immunosuppression alleviation, enhancement of chemotherapeutic and radiotherapeutic effects. However, apatinib also gets struck in dilemma of reversing multidrug resistance of chemotherapeutic agents while suffering drug resistance itself, and several difficulties should be tackled before full use of apatinib. In this review, we discuss the outstanding characteristics and main predicaments of apatinib as targeted therapy in advanced sarcomas.

Preclinical Quantification of Prostate Cancer-Associated Vascular Alterations in the Bone Microenvironment in vivo.

INTRODUCTION: Prostate cancer has a special predilection to form bone metastases. Despite the known impact of the microvascular network on tumour growth and its dependence on the organ-specific microenvironment, the characteristics of the tumour vasculature in bone remain unknown. METHODS: The cell lines LNCaP, DU145, and PC3 were implanted into the femurs of NSG mice to examine the microvascular properties of prostate cancer in bone. Tumour growth and the functional and morphological alterations of the microvasculature were analysed for 21 days in vivo using a transparent bone chamber and fluorescence microscopy. RESULTS: Vascular density was significantly lower in tumour-bearing bone than in non-tumour-bearing bone, with a marked loss of small vessels. Accelerated blood flow velocity led to increased volumetric blood flow per vessel, but overall perfusion was not affected. All of the prostate cancer cell lines had similar vascular patterns, with more pronounced alterations in rapidly growing tumours. Despite minor differences between the prostate cancer cell lines associated with individual growth behaviours, the same overall pattern was observed and showed strong similarity to that of tumours growing in soft tissue. DISCUSSION: The increase in blood flow velocity could be a specific characteristic of prostate cancer or the bone microenvironment.

Angiocrine signals regulate quiescence and therapy resistance in bone metastasis.

Bone provides supportive microenvironments for hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs) and is a frequent site of metastasis. While incidences of bone metastases increase with age, the properties of the bone marrow microenvironment that regulate dormancy and reactivation of disseminated tumor cells (DTCs) remain poorly understood. Here, we elucidate the age-associated changes in the bone secretome that trigger proliferation of HSCs, MSCs, and DTCs in the aging bone marrow microenvironment. Remarkably, a bone-specific mechanism involving expansion of pericytes and induction of quiescence-promoting secretome rendered this proliferative microenvironment resistant to radiation and chemotherapy. This bone-specific expansion of pericytes was triggered by an increase in PDGF signaling via remodeling of specialized type H blood vessels in response to therapy. The decline in bone marrow pericytes upon aging provides an explanation for loss of quiescence and expansion of cancer cells in the aged bone marrow microenvironment. Manipulation of blood flow - specifically, reduced blood flow - inhibited pericyte expansion, regulated endothelial PDGF-B expression, and rendered bone metastatic cancer cells susceptible to radiation and chemotherapy. Thus, our study provides a framework to recognize bone marrow vascular niches in age-associated increases in metastasis and to target angiocrine signals in therapeutic strategies to manage bone metastasis.

Clinical and Quantitative MRI Perfusion Analysis of Osteoid Osteomas Before and After Microwave Ablation.

AIM: Evaluation of osteoid osteoma (OO) perfusion characteristics pre and post microwave ablation (MWA) using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with clinical follow-up. MATERIALS AND METHODS: Patients with OO underwent T1-weighted 3D DCE-MRI at 3.0T pre and post MWA. Signal intensity (SI) and perfusion of lesions was measured. Patients answered a questionnaire for clinical follow-up. RESULTS: A total of 24 patients were included (mean age of 28 years; nine females); 21 DCE-MRI datasets were of sufficient quality for analysis. The mean SI of lesions, plasma flow, volume of distribution and pain level all decreased statistically significantly after ablation. CONCLUSION: Quantitative MRI-perfusion analysis allows for objective treatment evaluation after MWA of OO, plasma flow and volume of distribution seem to be reliable indicators for successful thermoablation. MWA is an effective treatment option for OO with a low risk profile and significant pain reduction after treatment.

Epigenetic modulators hydralazine and sodium valproate act synergistically in VEGI-mediated anti-angiogenesis and VEGF interference in human osteosarcoma and vascular endothelial cells.

Vascular endothelial growth inhibitor (VEGI; also referred to as TNFSF15 or TL1A) is involved in the modulation of vascular homeostasis. VEGI is known to operate via two receptors: Death receptor­3 (DR3) and decoy receptor­3 (DcR3). DR3, which is thus far the only known functional receptor for VEGI, contains a death domain and induces cell apoptosis. DcR3 is secreted as a soluble protein and antagonizes VEGI/DR3 interaction. Overexpression of DcR3 and downregulation of VEGI have been detected in a number of cancers. The aim of the present study was to investigate the effects of sodium valproate (VPA), a histone deacetylase inhibitor, in combination with hydralazine hydrochloride (Hy), a DNA methylation inhibitor, on the expression of VEGI and its related receptors in human osteosarcoma (OS) cell lines and human microvascular endothelial (HMVE) cells. Combination treatment with Hy and VPA synergistically induced the expression of VEGI and DR3 in both OS and HMVE cells, without inducing DcR3 secretion. In addition, it was observed that the combination of VPA and Hy significantly enhanced the inhibitory effect on vascular tube formation by VEGI/DR3 autocrine and paracrine pathways. Furthermore, the VEGI/VEGF­A immune complex was pulled down by immunoprecipitation. Taken together, these findings suggest that DNA methyltransferase and histone deacetylase inhibitors not only have the potential to induce the re­expression of tumor suppressor genes in cancer cells, but also exert anti­angiogenic effects, via enhancement of the VEGI/DR3 pathway and VEGI/VEGF­A interference.

Vascular modulation through exercise improves chemotherapy efficacy in Ewing sarcoma.

Recent studies in mouse models of cancer have shown that exercise improves tumor vascular function, thereby improving chemotherapy delivery and efficacy. However, the mechanisms underlying this improvement remain unclear and the effect of exercise on Ewing sarcoma (ES), a pediatric bone and soft tissue cancer, is unknown. The effect of exercise on tumor vascular hyperpermeability, which inversely correlates with drug delivery to the tumor, has also not been evaluated. We hypothesized that exercise improves chemotherapy efficacy by enhancing its delivery through improving tumor vascular permeability. We treated ES-bearing mice with doxorubicin with or without moderate treadmill exercise. Exercise did not significantly alter ES tumor vessel morphology. However, compared to control mice, tumors of exercised mice had significantly reduced hyperpermeability, significantly decreased hypoxia, and higher doxorubicin penetration. Compared to doxorubicin alone, doxorubicin plus exercise inhibited tumor growth more efficiently. We evaluated endothelial cell sphingosine-1-phosphate receptors 1 and 2 (S1PR1 and S1PR2) as potential mediators of the improved vascular permeability and increased function afforded by exercise. Relative to tumors from control mice, vessels in tumors from exercised mice had increased S1PR1 and decreased S1PR2 expression. Our results support a model in which exercise remodels ES vasculature to reduce vessel hyperpermeability, potentially via modulation of S1PR1 and S1PR2, thereby improving doxorubicin delivery and inhibiting tumor growth more than doxorubicin alone does. Our data suggest moderate aerobic exercise should be tested in clinical trials as a potentially useful adjuvant to standard chemotherapy for patients with ES.

Expression profiling of long noncoding RNAs associated with vasculogenic mimicry in osteosarcoma.

Osteosarcoma (OS) is the most common highly malignant bone tumor in teens. Vasculogenic mimicry (VM) is defined as de novo extracellular matrix-rich vascular-like networks formed by highly aggressive tumor cells. We previously reported the presence of VM and it is an unfavorable prognostic factor in OS patients. Long noncoding RNAs (lncRNAs) are aberrantly expressed in OS and involved in cancer cell VM. However, lncRNAs in VM formation of OS have not been investigated. We, therefore, profiled the expression of lncRNAs in highly aggressive OS cell line 143B compared with its parental poorly aggressive cell line HOS. The differentially expressed (DE) lncRNAs and messenger RNA (mRNAs) were subjected to constructed lncRNA-mRNA coexpressed network. The top-ranked hub gene lncRNA n340532 knockdown 143B cells were used for in vitro and in vivo VM assays. The annotation of DE lncRNAs was performed according to the coexpressed mRNAs by Gene Ontology and pathway analysis. A total of 1360 DE lncRNAs and 1353 DE mRNAs were screened out. lncRNA MALAT1 and FTX, which have known functions related to VM formation and tumorigenesis were identified in our data. The coexpression network composed of 226 lncRNAs and 118 mRNAs in which lncRNA n340532 had the highest degree number. lncRNA n340532 knockdown reduced VM formation in vitro. The suppression of n340532 also exhibited potent anti-VM and antimetastasis effect in vivo, suggesting its potential role in OS VM and metastasis. Furthermore, n340532 coexpressed with 10 upregulation mRNAs and 3 downregulation mRNAs. The enriched transforming growth factor-ß signaling pathway, angiogenesis and so forth were targeted by those coexpressed mRNAs, implying n340532 may facilitate VM formation in OS through these pathways and gene functions. Our findings provide evidence for the potential role of lncRNAs in VM formation of OS that could be used in the clinic for anti-VM therapy in OS.

How to Diagnose Enchondroma, Bone Infarct, and Chondrosarcoma.

Enchondromas are among the most common benign tumors seen in the skeleton. They are encountered frequently in routine clinical practice. The purpose of this review is to help radiologists confidently diagnose enchondroma and distinguish it from other entities, such as bone infarct, bone graft, and low-grade chondrosarcoma.

[Treatment of giant cell tumor of distal radius with vascular anastomosis with proximal graft of vascular].

Objective: To evaluate the curative effect of proximal fibula graft of vascular anastomosis for giant cell tumor(GCT) of distal radius of bone. Methods: 38 patients with distal radius GCT were treated with proximal articular graft of anastomotic vessels. We evaluated the wrist joint function before and after surgery using wrist activity, visual analogue scale(VAS)pain score, grip recovery rate and Cooney scoring system. Results: All patients' wounds healed in stage I, and recovered smoothly during the perioperative period. No obvious wrist deformity was observed during the follow-up period. Bony union was achieved at the tibial and humerus osteotomy ends. The average healing time was 11 weeks. At third month postoperatively, the patient's wrist motion ranged from dorsiflexion to palmar flexion (69.15±15.24)°, ulnar/spasm deviation was (22.74±10.55)°, grip strength was (88.69±12.75)%, wrist VAS pain The score was (2.45±1.11) points and the Cooney score was (89.58±11.25) points, which was significantly better than preoperation (all P<0.05). No recurrence or metastasis occurred during follow-up in all patients. Conclusions: Distal humerus GCT treated with distal radius with vascular anastomosis with proximal graft of vascular has little effect on the activity of the lower extremities. However, its reconstruction of the wrist joint function might achieve better results.

The bone microenvironment promotes tumor growth and tissue perfusion compared with striated muscle in a preclinical model of prostate cancer in vivo.

BACKGROUND: Prostate cancer-related morbidity is associated with its preferential spread to the bone. Although the molecular interactions between the bone microenvironment and cancer cells have been researched extensively, the relevance of the microvascular properties of prostate cancer bone metastases remains largely unknown. Most preclinical studies focusing on microvascular analyses are based on heterotopic tumor implantation, whereas the impact of the microenvironment on site-specific growth behavior and angiogenesis is rarely addressed. METHODS: The microvascular changes associated with tumor growth in bone and soft tissue were characterized by implanting single cell suspensions of LnCap, Du145, and Pc3 cells into the femur (femur window) or striated muscle (dorsal skinfold chamber) of NSG mice. Tumor growth and the local microvasculature were analyzed for 21 days using intravital fluorescence microscopy. RESULTS: The results showed a higher engraftment of tumor cells in bone than in striated muscle associated with accelerated growth of LnCap cells and Pc3 cells. Permeability, blood flow, and tissue perfusion rates were greater in bone than in striated muscle. Du145 cells showed similar growth behavior in both tissues with similar vascular properties. The bone microenvironment facilitated tumor engraftment and growth. Increased microvascular density in striated muscle led to a higher tumor burden during early growth, whereas the increased perfusion promoted later prostate cancer growth in bone. CONCLUSIONS: Monitoring prostate cancer microcirculation in bone and soft tissue may be useful to evaluate the organ-specific efficacy of new treatments.

Tumor thrombus in the large veins draining primary pelvic osteosarcoma on cross sectional imaging.

PURPOSE: To evaluate the frequency of tumor thrombus in the large veins draining primary pelvic osteosarcoma on early cross-sectional imaging studies and its effect on patient survival. MATERIALS AND METHODS: Our retrospective study included all patients with primary pelvic osteosarcoma treated at our facility between January 2000 and May 2014, who were ≤ 45 years of age, and had adequate imaging studies and clinical follow up. Four radiologists evaluated for tumor in the large draining veins on initial CT, MRI and PET/CTs. A consensus evaluation by the four radiologists together with findings on operative reports, pathology reports or follow-up imaging was used as the reference standard. RESULTS: Thirty-nine patients with primary pelvic osteosarcoma met final inclusion criteria. Tumor thrombus was identified in the large draining veins in 10 of the 22 (45%) patients who underwent tumor resection and 10 of the 17 (59%) who did not. In the 22 patients who underwent tumor resection, tumor thrombus was significantly associated with worse overall survival (p = 0.03). CONCLUSIONS: Tumor thrombus in the large draining veins is identified in a significant proportion of initial imaging studies in patients with pelvic osteosarcoma, and is associated with worse overall survival in patients who undergo tumor resection.

Activation of the complement system in an osteosarcoma cell line promotes angiogenesis through enhanced production of growth factors.

There is increasing evidence that the complement system is activated in various cancer tissues. Besides being involved in innate immunity against pathogens, the complement system also participates in inflammation and the modulation of tumor microenvironment. Recent studies suggest that complement activation promotes tumor progression in various ways. Among some cancer cell lines, we found that human bone osteosarcoma epithelial cells (U2-OS) can activate the alternative pathway of the complement system by pooled normal human serum. Interestingly, U2-OS cells showed less expression of complement regulatory proteins, compared to other cancer cell lines. Furthermore, the activated complement system enhanced the production of growth factors, which promoted angiogenesis of human endothelial cells. Our results demonstrated a direct linkage between the complement system and angiogenesis using the in vitro model, which suggest the complement system and related mechanisms might be potential targets for cancer treatment.