The understanding of how estrogen and progesterone (P 4 ) drive uterine remodeling in rodents has largely been based on studies involving administration of exogenous hormones, using steroid receptor-deficient mice, or relying on vaginal smears. In all these cases, the actual serum levels of 17b-estradiol (E 2 ) and P 4 are not directly measured, and the relationship between physiological levels of female sex hormones and uterine remodeling in cycling mice has not been fully explored. Here, we measured the circulating levels of E 2 and P 4 in cycling mice and performed correlation analysis between hormone levels and epithelial and stromal uterine parameters, irrespective of the estrous stage. In parallel, these parameters were analyzed in relation to the more conventional method of vaginal smear classification of estrous stage. We found that circulating P 4 inversely correlated with uterine width, luminal epithelial proliferation, stromal apoptosis, and degradation of luminal epithelial basement membrane collagen type-IV. Circulating E 2 positively correlated with uterine width, stromal cell proliferation, and collagen type-I content, while it negatively correlated with glandular epithelial proliferation, loss of collagen type-IV surrounding glandular epithelium, and apoptosis in luminal, glandular, and stromal compartments. Our findings indicate that measuring P 4 or E 2 levels can predict many concurrent cellular and stromal events in the mouse uterus, suggesting that in naturally cycling mice cellular responses to hormone changes are not delayed, but occur very rapidly.

Background-Despite the mounting clinical burden of heart failure, the biomolecules that control myocardial tissue remodeling are poorly understood. TIMP-3 is an endogenous inhibitor of matrix metalloproteinases (MMPs) that has been found to be deficient in failing human myocardium. We hypothesized that TIMP-3 expression prevents maladaptive tissue remodeling in the heart, and accordingly, its deficiency in mice would alone be sufficient to trigger progressive cardiac remodeling and dysfunction similar to human heart failure. Methods and Results-Mice with a targeted timp-3 deficiency were evaluated with aging and compared with age-matched wild-type littermates. Loss of timp-3 function triggered spontaneous LV dilatation, cardiomyocyte hypertrophy, and contractile dysfunction at 21 months of age consistent with human dilated cardiomyopathy. Its absence also resulted in interstitial matrix disruption with elevated MMP-9 activity, and activation of the proinflammatory tumor necrosis factor-␣ cytokine system, molecular hallmarks of human myocardial remodeling. Conclusions-TIMP-3 deficiency disrupts matrix homeostasis and the balance of inflammatory mediators, eliciting the transition to cardiac dilation and dysfunction. Therapeutic restoration of myocardial TIMP-3 may provide a novel approach to limit cardiac remodeling and the progression to failure in patients with dilated cardiomyopathy.

Increased pericellular proteolysis due to an imbalance between MMPs (matrix metalloproteinases) and TIMPs (tissue inhibitors of metalloproteinases) promotes early stages of tumorigenesis. We have reported that TIMP-1 down-regulation confers tumorigenicity on immortal Swiss 3T3 fibroblasts. In pursuit of the mechanism involved in this transformation, we asked whether MMP inhibitors modulate contact inhibition and cell adhesion, because the dysregulation of these events is essential for cellular transformation. Using both genetic and biochemical means, we demonstrate that MMP inhibitors regulate fibroblast cell adhesion. TIMP-1 down-regulated cells formed dense, multilayered colonies, suggesting a loss of contact inhibition. Recombinant TIMP-1 and synthetic MMP inhibitors (MMPi) restored normal cell contact and density of these cells in a dose-dependent manner. Consequently, the effect of MMPi on both cell-extracellular matrix (ECM) and cell-cell adhesion were investigated. Upon MMPi treatment, p125 FAK was redistributed, together with vinculin, to points of cell-ECM contact. Furthermore, phosphorylation of p125 FAK was restored to levels similar to that of wild type. In parallel, MMPi treatment increased cadherin levels and stabilized cadherin-mediated cell-cell contacts. Moreover, enhanced cadherin function was evident as increased calcium-dependent cell-cell aggregation and co-localization of cadherin and ␤-catenin at the cell membrane. We also obtained independent evidence of altered cadherin function using timp-1 ؊/؊ mouse embryonic fibroblasts. Our data provide provocative evidence that increased pericellular proteolysis impacts cell adhesion systems to offset normal contact inhibition, with subsequent effects on cell transformation and tumorigenesis. Matrix metalloproteinases (MMPs)1 and their tissue inhibitors (TIMPs) constitute a key system of pericellular proteolysis within the cell microenvironment. Our understanding of the role of this proteolytic system in cancer has evolved over the past decade. Initially linked to tumor invasion and metastasis, an MMP:TIMP imbalance is now thought to function in promoting early events of tumor development (1). The current emphasis is on identifying the mechanisms underlying these early effects. A better understanding of the relationship between MMP:TIMP activity and cell-extracellular matrix (ECM) and cell-cell communication is fundamental to this effort. We had reported that down-regulation of TIMP-1 expression caused an immortal fibroblast cell line to become tumorigenic (2). Extensive literature has since led to the knowledge that cancer involves a disrupted balance between MMPs and TIMPs. Both TIMPs and MMPs have been manipulated through genetic and biochemical approaches in tissue culture systems to demonstrate that, in general, TIMPs inhibit tumor cell invasion, angiogenesis, metastasis, and tumor formation (3-9), whereas MMPs promote these events (10 -13). Transgenic and knockout animals have further supported the role of this proteolytic system in early tumo...