We are presently investigating the involvement of matrix metalloproteinases (MMPs), MMP-7 (Pump-1, matrilysin) in particular, in the development of adenomyosis uteri. To examine whether progression of adenomyosis uteri might correlate with an expression of MMP enzyme activity, we initially utilized an animal model for adenomyosis uteri induced in pituitarygrafted mice. Gelatin zymography identified three distinct enzyme activities of MMP (20-30 kDa, 50 kDa, and 70 kDa) in extracts obtained from a uterus with adenomyosis, whereas no enzyme activities of MMP were demonstrated in those obtained from normal uterus. Since MMP enzyme activity of 20-30 kDa corresponds to the reported low molecular weight MMP-7 in an activated form (19 kDa) and an inactive form (28-29 kDa), the expression of MMP-7 mRNA was investigated by RT-PCR combined with Southern blot analysis. The result showed that a band of 440 bp PCR product was demonstrated in comparable amounts in both normal mouse uterus and mouse adenomyosis uteri, suggesting that an enhanced enzyme activity of MMP-7 observed in adenomyosis uteri may not be controlled solely at mRNA level. This suggestion was supported by subsequent human studies, the result of which showed a band of 440 bp PCR product in comparable amounts in both adenomyosis uteri and normal uterine endometrium. To examine the expression of MMP-7 protein in human adenomyosis uteri, Western blot analysis of the immunoreactive MMP-7 was performed in the same samples with those used in the study on the expression of the MMP-7 mRNA. Higher amounts of immunoreactive MMP-7 were observed in the epithelial cells of uterine adenomyosis than in those of normal uterine endometrium. The semi-quantitative scoring for immunoreactive MMP-7 staining showed that MMP-7 expression observed in adenomyosis uteri was menstrual cycle-independent and significantly higher than that in normal uterine endometrium, in which MMP-7 expression was menstrual cycle-dependent with its higher expression during the proliferation phase than during the early to mid secretory phase of the menstrual cycle. The data, taken together, are consistent with an idea that epithelial synthesis of MMP-7 in uterine adenomyosis contributes to its invasion into the myometrium
