Thrombospondin-1 and Transforming Growth Factor-β1 Levels in Prolactinoma and Their Clinical Significance

OBJECTIVE: To investigate the roles of angiogenesis, thrombospondin-1 (TSP-1) and transforming growth factor-beta(1) (TGF-beta(1)) in invasive and noninvasive prolactinoma. METHODS: TSP-1 and TGF-beta(1) protein were examined using immunohistochemistry and Western blotting in 81 prolactinomas. Angiogenesis was assessed by measuring microvessel density via CD34 immunostaining. RESULTS: Microvessel density was significantly higher in invasive prolactinomas than in noninvasive prolactinomas. Immunohistochemistry demonstrated that significantly fewer invasive prolactinomas were positive for TSP-1 compared with noninvasive prolactinomas (17.9% versus 50.0%, respectively), and significantly higher numbers of invasive prolactinomas were positive for TGF-beta(1) compared with noninvasive prolactinomas (82.1% versus 42.9%, respectively). Microvessel density was significantly lower in TSP-1-positive prolactinomas than in TSP-1-negative prolactinomas, and significantly higher in TGF-beta(1)-positive prolactinomas than in TGF-beta(1)-negative prolactinomas. CONCLUSIONS: These results suggest a close relationship between angiogenesis and tumour invasiveness in prolactinoma. TSP-1 and TGF-beta(1) may play important roles in the progression of prolactinoma, by affecting angiogenesis.