Circulating Levels of Thrombospondin-1 and Thrombospondin-2 in Patients with Common Brain Tumors

Angiogenesis is linked to the development of cancer and plays an important role in tumor growth and malignant transformation. Thrombospondin-1 (TSP-1) and thrombospondin-2 (TSP-2) are potent angiostatic molecules that were highly expressed in developing blood vessels. The objective of this study is to measure serum levels of TSP-1 and TSP-2 in patients with common brain tumors, namely high-grade glioma (HGG), low-grade glioma (LGG), and meningioma. For this prospective study, a total of 56 patients were operated on for supratentorial gliomas and meningiomas, and 18 healthy subjects were evaluated. Serum levels of angiostatic molecules were measured with enzyme-linked immunosorbent assay. The results of patients were compared with those of healthy subjects. High serum levels of TSP-1 were seen in HGG, followed by LGG, meningioma groups, and controls. The only significant difference was found between HGGs and controls (p = 0.004). There was a trend to decrease from HGG to controls. High serum levels of TSP-2 were seen in controls, followed by meningioma, LGG, and HGG. None of the patient groups showed significant differences compared with controls. Among the patient groups, TSP-2 was significantly higher in the meningioma group than the HGG group (p = 0.01). No correlation was found with any of the molecules and the clinical parameters, including the presence of peritumoral edema or seizure, the anterior-posterior diameter of the tumor, and, more importantly, the grade of glioma. Our results indicate that TSP-2 might be more important than TSP-1 in preventing angiogenesis and a major angiostatic factor in glioma cells.