Although trefoil factor 1 (TFF1; previously named pS2) is abnormally expressed in about 50% of human breast tumors, its physiopathological role in this disease has been poorly studied. Moreover, controversial data have been reported. TFF1 function in the mammary gland therefore needs to be clarified. In this study, using retroviral vectors, we performed TFF1 gain- or loss-of-function experiments in four human mammary epithelial cell lines: normal immortalized TFF1-negative MCF10A, malignant TFF1-negative MDA-MB-231 and malignant TFF1-positive MCF7 and ZR75.1. The expression of TFF1 stimulated the migration and invasion in the four cell lines. Forced TFF1 expression in MCF10A, MDA-MB-231 and MCF7 cells did not modify anchorage-dependent or -independent cell proliferation. By contrast, TFF1 knockdown in MCF7 enhanced soft-agar colony formation. This increased oncogenic potential of MCF7 cells in the absence of TFF1 was confirmed in vivo in nude mice. Moreover, chemically induced tumorigenesis in TFF1-deficient (TFF1-KO) mice led to higher tumor incidence in the mammary gland and larger tumor size compared with wild-type mice. Similarly, tumor development was increased in the TFF1-KO ovary and lung. Collectively, our results clearly show that TFF1 does not exhibit oncogenic properties, but rather reduces tumor development. This beneficial function of TFF1 is in agreement with many clinical studies reporting a better outcome for patients with TFF1-positive breast primary tumors.

The substrate of matrix metalloproteinase 11 (MMP11) remains unknown. We have recently shown that MMP11 is a negative regulator of adipogenesis, able to reduce and even to revert mature adipocyte differentiation. Here, we have used mouse 3T3L1 cells and human U87MG and SaOS cells to show that MMP11 cleaves the native a3 chain of collagen VI, which is an adipocyte-related extracellular matrix component. It is known that extracellular proteolytic processing of this chain is required for correct collagen VI folding. Interestingly, MMP11-deficient fat tissue is less cohesive and exhibits collagen VI alteration, dramatic adipocyte plasma and basement membrane abnormalities and lipid leakage. MMP11 is thus required for correct collagen VI folding and therefore for fat tissue cohesion and adipocyte function. Both MMP11 and collagen VI favor tumor progression. Similar spatio-temporal overexpression at the adipocyte-cancer cell interface has been reported for the two proteins. MMP11-dependent collagen VI processing might therefore be expected to occur during malignancy. Accordingly, collagen VI no longer delineates adipocytes located at the invasive front of breast carcinomas. In conclusion, the native a3 chain of collagen VI constitutes a specific MMP11 substrate. This MMP11 collagenolytic activity is functional in fat tissue ontogenesis as well as during cancer invasive steps.

No abstract

Low-density lipoprotein receptor-related protein-(LRP-1) is a large endocytic receptor that binds more than 35 ligands and exhibits signaling properties. Proteinases capable of degrading extracellular matrix (ECM), called matrix proteinases in this paper, are mainly serine proteinases: the activators of plasminogen into plasmin, tissue-type (tPA) and urokinase-type (uPA) plasminogen activators, and the members of the matrix metalloproteinase (MMP) family. LRP-1 is responsible for clearing matrix proteinases, complexed or not with inhibitors. This paper attempts to summarize some aspects on the cellular and molecular bases of endocytic and signaling functions of LRP-1 that modulate extra- and pericellular levels of matrix proteinases.

Tissue inhibitor of metalloproteinases-1 (TIMP-1) regulates the extracellular matrix turnover by inhibiting the proteolytic activity of matrix metalloproteinases (MMPs). TIMP-1 also displays MMP-independent activities that influence the behavior of various cell types including neuronal plasticity, but the underlying molecular mechanisms remain mostly unknown. The trans-membrane receptor low-density lipoprotein receptor-related protein-1 (LRP-1) consists of a large extracellular chain with distinct ligand-binding domains that interact with numerous ligands including TIMP-2 and TIMP-3 and a short transmembrane chain with intracellular motifs that allow endocytosis and confer signaling properties to LRP-1. We addressed TIMP-1 interaction with recombinant ligand-binding domains of LRP-1 expressed by CHO cells for endocytosis study, or linked onto sensor chips for surface plasmon resonance analysis. Primary cortical neurons bound and internalized endogenous TIMP-1 through a mechanism mediated by LRP-1. This resulted in inhibition of neurite outgrowth and increased growth cone volume. Using a mutated inactive TIMP-1 variant we showed that TIMP-1 effect on neurone morphology was independent of its MMP inhibitory activity. We conclude that TIMP-1 is a new ligand of LRP-1 and we highlight a new example of its MMP-independent, cytokine-like functions.

Abstract. Alcohol consumption is a well-established risk factor for hormone-dependent breast cancer. In vitro studies performed to understand the mechanisms by which ethanol acts on breast cancer cells have shown that this compound stimulates both proliferation and migration. In the present study, we show by gelatin zymography that, when exposed to ethanol, MCF-7 human breast cancer cells display a higher amount of active metalloproteinases (MMP) 2 and 9 in their culture medium. This increase is somewhat higher than those observed in the case of 17ß-estradiol (E 2 ) exposure. As expected, anti-estrogen ICI 182,780 inhibits the E 2 -induced overexpression of a well-known estrogen responsive gene, the progesterone receptor, in MCF-7 cells. ICI 182,780 also inhibits the E 2 -induced increase in MMP-2 and -9 secretion. Nevertheless, in the case of ethanol exposure, this ER antagonist was only efficient on MMP-9 secretion. In addition, although MMP-9 transcription was not sensitive to E 2 or ethanol, MMP-2 transcription was stimulated in MCF-7 cells exposed to ethanol. Collectively, these results give new insights into the effects of alcohol on breast cancer cell migration, which are not due solely to an estrogen-like activity of alcohol.

Alcohol consumption is an increased risk factor for hormone-dependent breast cancer but the underlying molecular bases are unknown. Several studies suggest that ethanol could activate the estrogen signaling pathway. We have performed an in vitro study in order to investigate the molecular players involved in this phenomenon. Exposure of MCF-7 breast cancer cells to ethanol induced an increase in the mRNA level of two well known estrogen target genes: progesterone receptor (PR) and pS2. This result was confirmed by an increase in luciferase activity in pEREtkLuc-transfected MCF-7 cells exposed to ethanol. These effects, whose intensity was similar to those of E 2 , were observed also in steroid-free medium and were inhibited by the antiestrogen ICI 182,780. This suggested a ligand-independent activation of ERα that was confirmed by the absence of ERα proteolysis in ethanol-treated cells. Using PKA inhibitor (H89), the study of phospho-CREB by Western blot and transfection experiments with a CRE-reporter construct demonstrated that PKA was involved in ethanol-induced transcription of ERα target genes. Adenylyl cyclase inhibition impaired the activation of estrogen signaling pathway induced by ethanol. The results obtained in vitro, are discussed in regard to alcohol consumption and relevance to humans.

This study presents the bio-guided chemical investigation of a 80% methanol extract of Hippocrepis emerus flowers, a perennial non-climbing shrub. Liquid-liquid partitioning in solvents of increasing polarity combined to biological screening enabled to determine the EtOAc and n-BuOH soluble fractions as the most active parts of the extract. These fractions were chemically profiled by using a 13 C NMR-based dereplication method, resulting in the identification of twenty-six compounds. The dereplication process was completed by purification of some unknown or minor compounds of the n-BuOH fraction. Three new glycosylated flavonoids, namely kaempferol-3-O-β-D-glucopyranosyl-7-O-β-Dglucopyranosyl-(1→3)-α-L-rhamnopyranoside (1), isorhamnetin-3-O-β-D-glucopyranosyl-7-O-β-D-glucopyranosyl-(1→3)-α-L-rhamnopyranoside (2) and quercetin-3-O-β-Dglucopyranosyl-7,4'-O-α-L-dirhamnopyranoside (3), together with twelve known compounds (4 -15) were isolated. Their structures were elucidated by spectroscopic methods including NMR, HR-ESI-MS and UV. The antioxidant activity of fractions and isolated compounds were evaluated using DPPH and hydroxyl radical scavenging and CUPRAC assays. In parallel, their inhibitory properties against mushroom tyrosinase and human neutrophil elastase enzymes were assessed. Three quercetin glycosides exhibited a significant radicalscavenging activity and two flavonoids showed a moderate elastase inhibitory activity.