EXPRESSION OF METALLOPROTEINASES AND THEIR INHIBITORS IN HUMAN TROPHOBLAST CONTINUOUS CELL-LINES

Trophoblasts cells which are derived from the outer layer of the blast ocyst have developed mechanisms by which they can invade the uterus an d tap into the maternal circulation. In contrast to tumor cell invasio n trophoblast invasion is precisely regulated, being. 4confined spatia lly to the uterus and temporally to early pregnancy. The invasive prop erties manifested by trophoblasts are made possible by the secretion o f proteolytic enzymes which can degrade components of the extracellula r matrix (ECM), A number of investigators have shown that the matrix m etalloproteinases (MMPs) are important mediators of trophoblast invasi on. The two type TV collagenases, MMP-2 and MMP-9, which specifically degrade type IV collagen and gelatins have been of particular interest in this respect, Ire this paper we examine the expression and regulat ion of MMPs and their inhibitors in a series of trophoblast continuous cell lines. These cell lines, ED27, ED31, ED77, and a choriocarcinoma cell line, BeWo, were initially characterized with respect to various properties, including cytokeratin, hCG, and hPL expression. We have l ooked at the expression of MMPs and their inhibitors in these cell lin es and their in vitro invasive behavior, Using zymography and RT-PCR w e show that the trophoblast cell lines produce both MMP-2 and MMP-9, w hile the BeWo produce only MMP-2. Using an in vitro invasion assay the trophoblast cell lines were shown to be capable of invading while the BeWo were unable to invade, These results suggest that expression of MMP-9 in these cells is crucial for invasion. We have also examined th e regulation of MMP expression by cytokines and found that MMP-9 expre ssion could be modulated by IL-1 beta in these cell lines. The data pr esented in this paper suggest that these trophoblast cell lines presen t an ideal model system to investigate the regulation of metalloprotei nases in trophoblast invasion. (C) 1998 Academic Press.