Co-Expression of Vascular Endothelial Growth Factor and Its Receptor flt-1 in Malignant Pleural Mesothelioma

Background: Vascular endothelial growth factor (VEGF) is a potent angiogenic protein with a selective mitogenic effect on endothelial cells known to be involved in many normal and pathological processes. Coexpression of VEGF and its receptor flt-1 has been reported in different types of malignant tumors. Objective: In the present study we investigated the expression of VEGF and flt-1 in 90 cases of diffuse malignant pleural mesotheliomas. Methods: VEGF and flt-1 expression was analyzed by immunohistochemistry and non-radioactive in situ hybridization. Results: VEGF expression was visualized immunohistochemically in tumor cells. flt-1 expression correlated with histological differentiation (p < 0.013). Furthermore, expression of flt-1 was detected in tumor cells, macrophages and microvessels adjacent to tumor cells. VEGF and flt-1 expression were confirmed by in situ hybridization. Conclusion: There was a statistically significant correlation between VEGF and flt-1 expression (p < 0.001). The observed coexpression of VEGF and flt-1 possibly suggests a potential autocrine loop for malignant pleural mesothelioma cells.