Expression of metalloproteases and their inhibitors in different histological types of breast cancer

Metalloproteases (MMPs) and their tissue inhibitors of metalloproteases (TIMPs) are involved in several key aspects of tumoral growth, invasion and metastasis. The purpose of this study was to characterize on how the different histological types of breast cancer differ in the expression of several components of this enzymatic system. An immunohistochemical study was performed in 50 ductal, 23 lobular, 14 mucinous, 7 tubular, 4 papillary and 5 medullary invasive carcinomas, using tissue arrays and specific antibodies against 7 MMPs and 3 tisullar TIMPs. Staining results were categorized by means of a specific software program (score values). Carcinomas of the ductal type showed higher score values for MMPs and TIMPs than the other histological types; whereas mucinous carcinomas had lower scores values for expressions of the majority of these proteins. Stromal fibroblasts were more frequently positive for MMP-1, -7 and -13 and TIMP-1 and -3, when present in carcinomas of the ductal type than in other histological types of breast carcinomas. Stromal mononuclear inflammatory cells were more frequently positive for MMP-1 and TIMP-3, but more often negative for MMP-7, -9 and -11, when located in carcinomas of the ductal type than in other histological types of breast carcinomas. We found variations in MMP/TIMP expressions among the different histological subtypes of breast carcinomas suggesting differences in their tumor pathophysiology.