Expression of matrix metalloproteinases in patients with uterine smooth muscle tumors: an immunohistochemical analysis of MMP-1 and MMP-2 protein expression in leiomyoma, uterine smooth muscle tumor of uncertain malignant potential, and leiomyosarcoma.

Abstract

Matrix metalloproteinases (MMPs) have been suggested to play an important role in tumor invasion and metastasis. We compared the expression of MMP-1 and MMP-2 protein in patients with leiomyoma, uterine smooth muscle tumor of uncertain malignant potential (STUMP), and leiomyosarcoma (LMS). MMP-1 and MMP-2 expression was investigated by immunohistochemistry from paraffin-embedded tissue in 26 patients with leiomyoma, in 24 patients with STUMP, and in 21 patients with LMS. MMP-1 was expressed in 92% of leiomyomas, in 83% of STUMP, and in 86% of LMS, whereas MMP-2 was expressed in 12% of leiomyomas, in 17% of STUMP, and in 48% of LMS. A statistically significant difference regarding the frequency of MMP-2 expression was observed between LMS and STUMP (P =.025) as well as between LMS and leiomyoma (P =.006), but not between STUMP and leiomyoma (P >.05). Likewise, the staining intensity did significantly differ between LMS and leiomyoma (P =.025), but no statistical significant difference was observed between LMS and STUMP (P >.05) and between STUMP and leiomyoma (P >.05). The stronger MMP-2 expression in patients with LMS compared with STUMP and leiomyoma indicates that this protein might be a marker for tumor invasion or metastasis in patients with uterine LMS. Furthermore, MMP-2 seems to be a useful immunohistochemical parameter to distinguish cases of smooth muscle tumors in which histologic features are ambiguous or borderline. Further studies including larger numbers of patients are necessary to establish MMP-2 as a routine marker for tumor invasion and progression.