Abstract 1434: EMMPRIN expression is associated with metastatic progression in osteosarcoma

Abstract

Abstract Introduction: Despite the improvement of survival in localized osteosarcoma patients, patients with metastasis still carry a poor prognosis. Thus, identification of factors contributing to metastasis is needed. Extracellular matrix metalloproteinase inducer (EMMPRIN) is a cell-surface glycoprotein which plays multiple roles in physiologic and pathologic conditions. EMMPRIN is highly expressed in several cancers and stimulates adjacent stromal cells or tumor cells to produce matrix metalloproteinase (MMP). EMMPRIN also stimulates expression of vascular endothelial growth factor (VEGF) which leads to angiogenesis. These findings have made EMMPRIN an attractive therapeutic target in many cancer types. The goals of this study were; to investigate the expression of EMMPRIN in osteosarcoma; to examine if EMMPRIN, via tumor-stroma interaction, is associated with metastatic potential in osteosarcoma. Methods: Level of EMMPRIN mRNA expression was evaluated by RT-PCR in 6 tumor-derived osteosarcoma cell lines and by immunohistochemistry prechemotherapy biopsies from 52 patients. Clinical data of these patients were reviewed to examine the association of EMMPRIN expression and clinical outcome. Transfection of EMMPRIN-targeting siRNA in SaOS-2 was performed to test the role of EMMPRIN in osteosarcoma progression. To study the role of EMMPRIN in tumor-stromal interaction, co-culture of SaOS-2 with osteoblast (hFOB) was experimented. Functional in vitro assays that reflect metastatic potential of osteosarcoma cells were performed. MMP production, VEGF production, cell invasion and proliferation were studied by gelatin zymography, VEGF ELISA, Matrigel invasion assay and WST-1 assay, respectively. Results: EMMPRIN was expressed in 90% by immunohistochemistry with strong accentuation along the cell membrane. Level of EMMRIN mRNA expression was significantly higher in 5 of 6 tumor-derived cell lines compared to MG63. Patients with high EMMPRIN expression had significantly worse metastasis-free survival. EMMPRIN mRNA levels was significantly down-regulated by siRNA transfection compared to control-siRNA transfected cell. Co-culture of osteoblast and SaOS-2 enhanced stimulation of pro-MMP2. This stimulation was reversed by transfection of SaOS-2 with EMMPRIN-targeting siRNA. Number of cells crossing the chamber was statistically lower in EMMPRIN-siRNA transfected cells. When osteoblast and SaOS-2 were co-cultured, VEGF expression was increased compared to SaOS-2 only culture. EMMPRIN-targeting siRNA transfection resulted in decrease of VEGF expression. SaOS-2 cells transfected with EMMPRIN-siRNA showed decreased proliferation potential compared to control-siRNA transfected cells. Conclusion: Our data suggest that highly expressed EMMPRIN plays an important role in metastatic potential of osteosarcoma. EMMPRIN could serve as a potential therapeutic target in osteosarcoma. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1434.