IADR Abstract Archives
Revealing the Autocrine and Paracrine Role of VEGF Metastatic Potential
Objectives: Osteosarcoma (OS) is the most common bone malignancy affecting the long bones and jaw. Survival rate of patients with metastatic-osteosarcoma (OS) is 20% and have not been changed for decades. Treatment protocols include chemotherapy and surgery. Angiogenesis is an important process that contributes to tumor growth, invasion and metastasis. Vascular endothelial growth factor (VEGF) is one of the main players in angiogenesis. In human OS biopsies we found high levels of VEGF and CD 31 in metastatic-OS compared to non-metastatic tumors. Aim: to investigate the autocrine and paracrine role of VEGF in osteosarcoma invasion.
Methods: The expression of VEGF receptors in OS cells was assessed by FACS and RT-PCR. VEGF secretion by OS cells was measured by ELISA. The effect of VEGF on human OS cells (U2-OS) invasion was examined in-vitro by:1) exogenous addition of VEGF to the culture media 2) silencing of VEGF in OS cells. Following VEGF addition/inhibition, western blot was performed to reveal up/down phosphorylation of signaling pathways
Results: human OS cells expressed VEGF receptor 2 and secreted high concentrations of VEGF (3.9ng/ml). Exogenous addition of VEGF to OS culture enhanced cell invasion (1.9 fold) and phosphorylation of AKT (x2.5 fold), indicating that VEGF promotes OS invasion in a paracrine manner. VEGF silencing decreased OS invasion (x11 folds) and AKT phosphorylation (x2.2 folds) suggesting an autocrine role of VEGF in OS invasion.
Conclusions: VEGF plays a dual role in osteosarcoma invasion via VEGF/AKT pathway, more predominantly by an autocrine signaling. Its inhibition may suppress OS metastatic potential therefore pave the way for the development of a novel biological therapy for OS.
Methods: The expression of VEGF receptors in OS cells was assessed by FACS and RT-PCR. VEGF secretion by OS cells was measured by ELISA. The effect of VEGF on human OS cells (U2-OS) invasion was examined in-vitro by:1) exogenous addition of VEGF to the culture media 2) silencing of VEGF in OS cells. Following VEGF addition/inhibition, western blot was performed to reveal up/down phosphorylation of signaling pathways
Results: human OS cells expressed VEGF receptor 2 and secreted high concentrations of VEGF (3.9ng/ml). Exogenous addition of VEGF to OS culture enhanced cell invasion (1.9 fold) and phosphorylation of AKT (x2.5 fold), indicating that VEGF promotes OS invasion in a paracrine manner. VEGF silencing decreased OS invasion (x11 folds) and AKT phosphorylation (x2.2 folds) suggesting an autocrine role of VEGF in OS invasion.
Conclusions: VEGF plays a dual role in osteosarcoma invasion via VEGF/AKT pathway, more predominantly by an autocrine signaling. Its inhibition may suppress OS metastatic potential therefore pave the way for the development of a novel biological therapy for OS.