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-β1 (TGF-β1) in invasive and noninvasive prolactinoma.

METHODS

TSP-1 and TGF-β1 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-β1 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-β1-positive prolactinomas than in TGF-β1-negative prolactinomas.

CONCLUSIONS

These results suggest a close relationship between angiogenesis and tumour invasiveness in prolactinoma. TSP-1 and TGF-β1 may play important roles in the progression of prolactinoma, by affecting angiogenesis.