Differentiation-dependent expression of gelatinase B/matrix metalloproteinase-9 in trophoblast cells

The purpose of this study was to evaluate the Rcho-1 trophoblast culture sy stem as a model for studying trophoblast invasion and to examine stage-spec ific expression of enzyme(s) potentially participating in rat trophoblast g iant cell invasive behavior. The invasive behavior of the differentiating R cho-1 trophoblast cells was demonstrated using Matrigel invasion chambers. Gelatin zymography and Western blot analysis of conditioned medium from dif ferentiating Rcho-1 trophoblast cell cultures and rat ectoplacental cone ou tgrowths revealed a differentiation-dependent increase in gelatinase B/matr ix metalloproteinase (MMP-9). Nothern blot and reverse transcriptase polyme rase chain reaction (RT-PCR) analyses of Rcho-1 trophoblast or ectoplacenta l cone cells also showed increasing expression of MMP-9 accompanying cell d ifferentiation. Rcho-1 trophoblast cells stably transfected with MMP-9 prom oter/luciferase reporter constructs exhibited a differentiation-dependent i ncrease in MMP-9 promoter activation. In conclusion, trophoblast giant cell differentiation is characterized by transcriptional activation of the MMP- 9 gene and appearance of the invasive phenotype.