Invasiveness of breast cancer cells MDA‐MB‐231 through extracellular matrix is increased by the estradiol metabolite 4‐hydroxyestradiol

Abstract

In malignant breast cancer, estrogen metabolism is altered, favoring the accumulation of hydroxyestradiols, which can generate free radicals. These reactive species can activate matrix metalloproteinases (MMPs), which in turn can hydrolyze the proteins of the extracellular matrix (ECM) that act as a barrier to tumor cell passage. The aim of this study was to determine whether reactive oxygen species generated by 4-hydroxyestradiol (4-OHE 2 ) can activate MMP-2 and then enhance the invasiveness of breast cancer cells MDA-MB-231 in vitro. Invasion and metastases development require the degradation of the extracellular matrix (ECM), which acts as a barrier to tumor cell passage. ECM consists of interstitial matrix and basement membrane (BM). The first step of tumor invasion is characterized by the degradation of BM components, particularly type IV collagen, laminin and proteoglycan. 1 Cancer cells can then migrate through the interstitial matrix by breaking down its protein components and then either entering the lymphatic capillaries or migrating a second time through BM to reach the blood stream.ECM proteins can be degraded by proteases, mainly the matrix metalloproteinases (MMPs). 2,3 In breast cancer, MMP-1, MMP-2, MMP-3, MMP-7, MMP-9 and MMP-13 are frequently detected; however, their respective importance for breast cancer progression still needs to be investigated. 4 -6 Nevertheless, the expression of MMP-2 has been linked to invasiveness of breast carcinoma cells, and its detection in breast carcinoma tissue was associated with a shortened recurrence-free survival. 7,8 MMPs are released under an inactive form (proMMPs) by cancer cells, but also by the stroma, i.e., fibroblast and endothelial cells. 9,10 Under their inactive proMMP forms, the propeptide domain covers the active site blocking access to substrate. This configuration is stabilized through the interaction between a cysteine located at a key position in the propeptide and a zinc atom at the MMP active site. 11,12 Expression and activation of proMMPs are considered to be important steps in metastases development. 2 It is proposed that proMMP-2 activation involves the cleavage of its propeptide by a membrane type 1-matrix metalloproteinase (MT1-MMP) molecule located on cell surfaces. ProMMP-2 binds to MT1-MMP using TIMP-2 as an adaptor by forming a trimolecular complex on the cell surface. 13 In this complex, the N-terminal domain of the tissue-inhibitor of matrix metalloproteinase 2 (TIMP-2) binds the catalytic domain of MT1-MMP and its C-terminal domain binds the hemopexin-like domain of proMMP-2. Another MT1-MMP near the complex cleaves the propeptide bond of proMMP-2 and generates an intermediate form, which is then converted into a fully active enzyme by an autoproteolytic mechanism. Consequently, active MMP-2 is then located directly at the migration front. 13,14 On the other hand, TIMP-2 plays a dual role since it can also inhibit MMP-2 by forming noncovalent associations with the active site of the MMP-2.ProMMP activation can also be achiev...

Hormonal regulation of catechol-O-methyl transferase activity in women with uterine leiomyomas

“…These reactive species activate matrix metalloproteinases, which in turn can hydrolyze the proteins of the extracellular matrix (18). Thus, up-regulation of COMT will favor the repaid clearance of catechol Es and consequently down-regulation of metalloproteinase enzymes.…”

In vitro irradiation of basement membrane enhances the invasiveness of breast cancer cells

“…Conditioned media were obtained using FBS-free culture medium to eliminate the endogenous proMMPs found in FBS. The conditioned media were concentrated 20 times using the Centricon YM30 column (Millipore, Etobicoke, Ontario, Canada) and samples were then analysed on a zymography gel as previously described (Paquette et al, 2005). Zymography is a non-reducing acrylamide gel polymerised with an MMP-2 and MMP-9 Substrate, gelatine.…”

Circulating Estrogen Metabolites and Risk for Breast Cancer in Premenopausal Women

“…Catecholestrogens, which include 2-and 4-hydroxyestrogens, may induce DNA damage through redox cycling, which generates reactive oxygen species and form reactive semiquinones and quinones capable of forming adducts with glutathione and purines in DNA. Measurement of 4-hydroxyestrone, which is thought to have greater estrogenic and genotoxic potential than 2-hydroxyestrone (48–50), would be of particular interest.…”