EXPRESSION OF MESSENGER-RIBONUCLEIC-ACID ENCODING MATRIX METALLOPROTEINASES AND THEIR TISSUE INHIBITORS IS RELATED TO MENSTRUATION

Matrix metalloproteinases (MMP) degrade components of the extracellula r matrix and the balance between enzyme production and that of their s pecific tissue inhibitors (TIMPs) is likely to be crucial for menstrua tion. The temporal expression of messenger (m) RNA for proMMP-1 (inter stitial collagenase), proMMP-3 (stromelysin 1), TIMP-1 and TIMP-2 has been examined by Northern analysis in 73 individually-dated endometria l tissue samples from normal women. Thirteen tissues expressed the mRN A for proMMP-3 and mRNA for proMMP-1 was detected in eleven of the sam e tissues. All of these tissues were from the menstrual(l 1) or perime nstrual (2) phases. No expression of mRNA for proMMP-1 or -3 was detec ted between cycle days 4 and 26. By contrast, mRNA for both TIMP-1 and TIMP-2 was detected in all tissue samples. The abundance of mRNA for TIMP-1 was significantly elevated in menstrual tissue compared with ti ssue from the rest of the cycle. TIMP-2 mRNA expression displayed cons iderable variability between individual tissues but mean abundance was also higher in menstrual tissue. Menstruation is therefore associated with a perturbation of the balance between the expression of MMPs and their tissue inhibitors which could lead to tissue degradation.