Matrix Metalloproteinases Play an Active Role in Wnt1-Induced Mammary Tumorigenesis

Abstract

The Wnt signaling transduction pathway plays a critical role in the pathogenesis of several murine and human epithelial cancers. Here, we have used mouse mammary tumor virus (MMTV)-Wnt1 transgenic mice, which develop spontaneous mammary adenocarcinoma, to examine whether matrix metalloproteinases (MMPs)-a family of extracellular proteases implicated in multiple steps of cancer progressioncontributed to Wnt1-induced tumorigenesis. An analysis of the expression of several MMPs by RT-PCR and in situ hybridization revealed an increase in the expression of MMP-2, MMP-3, MMP-9, MMP-13, and MT1-MMP (MMP-14) in hyperplastic glands and in mammary tumors of MMTV-Wnt1 transgenic mice. Interestingly, whereas MMP-2, MMP-3, and MMP-9 were exclusively expressed by stromal cells in mammary tumors, MMP-13 and MT1-MMP were expressed by transformed epithelial cells in addition to the tumor stroma. To determine whether these MMPs contributed to tumorigenesis, MMTVWnt1 mice were crossed with transgenic mice overexpressing tissue inhibitor of metalloproteinase-2-a natural MMP inhibitor-in the mammary gland. In the double MMTV-Wnt1/tissue inhibitor of metalloproteinases-2 transgenic mice, we observed an increase in tumor latency and a 26.3% reduction in tumor formation. Furthermore, these tumors grew at a slower rate, exhibited an 18% decrease in proliferative rate, and a 12.2% increase in apoptotic rate of the tumor cells in association with a deficit in angiogenesis when compared with tumors from MMTV-Wnt1 mice. Thus, for the first time, the data provides evidence for the active role of MMPs in Wnt1-induced mammary tumorigenesis. (Cancer Res 2006; 66(5): 2691-9)

Stromelysin-1 (MMP-3) is a target and a regulator of Wnt1-induced epithelial-mesenchymal transition (EMT)

“…Accordingly, we previously reported an upregulation of the expression of several MMPs in the mammary tumors of MMTV/Wnt1 transgenic mice. We also demonstrated that when crossed with mice overexpressing Tissue Inhibitor of Metalloproteinases (TIMP)-2 under the same MMTV promoter, double transgenic mice develop fewer tumors with an increased latency, 29 suggesting therefore that MMPs may also play a contributory role in Wnt1-mediated malignant transformation. Here we have used Wnt1 overexpressing C57MG mouse mammary epithelial cells to demonstrate that MMPs are both targets and contributors to Wnt-induced EMT.…”

“…42 We previously reported that overexpression of TIMP-2 in the mammary glands of MMTV-Wnt1 mice inhibited tumor formation suggesting that MMP inhibition could prevent or delay malignant transformation of epithelial cells. 29 Here, using the same MMTV-Wnt1 transgenic tumor model, we examined the effect of a preventive treatment using low dose (50 mg/kg) of a small MMP inhibitor, AG3340, that was administered twice a week. In previous experiments we had used higher doses (100 mg/kg) of the inhibitor administered twice daily by gastric gavage.…”

“…SDS-PAGE zymographies were performed in gels containing either 1% gelatin or casein as substrate as previously described. 29 For western blots, gels were transferred to a nitrocellulose membrane, blocked overnight at 4°C in TBS/0.05% Tween (TBST) containing 5% dry milk, incubated with the primary antibodies for 2 h at room temperature, washed in TBST and incubated with horseradish peroxidase (HRP)-conjugated secondary antibodies. Proteins were detected using the ECL reagent (Amersham Life Science, Buckinghamshire, UK).…”

Stem Cell versus Cancer and Cancer Stem Cell: Intricate Balance Decides Their Respective Usefulness or Harmfulness in the Biological System

“…Various molecular events, which were involved in aberrant remodeling in this model of mammary tumorigenesis included extracellular matrix modulators (Matrix Metalloproteinases (MMP)/ Tissue Inhibitors of Matrix Metallo-proteinases (TIMP) [80], soluble peptide factors/co-receptors Fgf8 [81], Lrp6 [82], and cell surface proteins (Syndecan-1) [83]. Moreover, about 50 molecules were identified as remodeling factors, and the effect of individual factors on such remodeling events needed to be assessed.…”

Review of: Metalloproteinase axes increase β-catenin signaling in primary mouse mammary epithelial cells lacking TIMP3

“…Overexpression of Wnt1 in the virgin mammary gland that activates a canonical Wnt/b-catenin/Lef-1 signaling pathway can produce precocious alveolar hyperplasia and ductal hyper-branching, which eventually results in the development of mammary adenocarcinomas [16]. An increase in the expression of MMP2, MMP3 and MMP9 occurs in the mammary stroma of Wnt1 transgenic mice whereas MMP13 is expressed by the transformed mammary epithelial cells (MECs), suggesting that additional MMPs other than MMP2 and MMP3 can contribute to tumor progression after sustained activation of a Wnt/b-catenindependent pathway [17]. Finally, during pregnancy, lobuloalveolar development is regulated by progesterone and prolactin.…”