Comparative study of the immunohistochemical expression of tissue inhibitors of metalloproteinases 1 and 2 between clearly invasive carcinomas and "in situ" trophoblast invasion.

Tissue inhibitors of metalloproteinases (TIMPs) play an important role in extracellular matrix homeostasis by regulating MMP activity. Although they were initially considered inhibitors of tumor growth and metastasis, recently their role in cancer progression has been controversial. The aim of our study was to compare the immunohistochemical expression of TIMP1 and TIMP2 between an uncontrollably invasive phenomenon (cancer) and an "in situ" process (trophoblast invasion) in an effort to assess any differential role of these molecules between these two distinct phenomena and therefore to understand better their contribution in cancer invasion and migration. We performed an immunohistochemical analysis of 50 carcinomas (colorectal, gastric, breast, pulmonary, and renal) and 40 first trimester gestations. The marker expression was evaluated semiquantitatively, separately in cancer parenchymal and trophoblastic cells as well as in malignant stromal and decidual cells, according to a percentage scale (0, <10, 10-50, and >50%) and according to staining intensity (0, +, ++, and +++). Our results showed that there was no statistically significant difference in TIMP1 expression between cancer parenchymal cells and trophoblastic cells. On the other hand, TIMP1 was expressed more often in decidual cells than in cancer stromal cells. Immunostaining for TIMP2 was more extensive and intense both in trophoblastic and decidual cells than in cancer parenchymal and stromal cells, respectively. The reduced expression of TIMP2 in metastatic carcinomas by comparison with non-metastatic gestation specimens underlines its importance in cancer invasion and migration. On the other hand, TIMP1 was more expressed in decidua than cancer stroma, but at the same time showed no statistically significant difference between cancer parenchyma and trophoblasts, highlighting its multifunctional activity in cancer progression.