Mélanie Mestdagt

Regulation of vimentin by SIP1 in human epithelial breast tumor cells

The expression of Smad interacting protein-1 (SIP1; ZEB2) and the de novo expression of vimentin are frequently involved in epithelial-to-mesenchymal transitions (EMTs) under both normal and pathological conditions. In the present study, we investigated the potential role of SIP1 in the regulation of vimentin during the EMT associated with breast tumor cell migration and invasion. Examining several breast tumor cell lines displaying various degrees of invasiveness, we found SIP1 and vimentin expression only in invasive cell lines. Also, using a model of cell migration with human mammary MCF10A cells, we showed that SIP1 is induced specifically in vimentin-positive migratory cells. Furthermore, transfection of SIP1 cDNA in MCF10A cells increased their vimentin expression both at the mRNA and protein levels and enhanced their migratory abilities in Boyden Chamber assays. Inversely, inhibition of SIP1 expression by RNAi strategies in BT-549 cells and MCF10A cells decreased vimentin expression. We also showed that SIP1 transfection did not activate the TOP-FLASH reporter system, suggesting that the β-catenin/TCF pathway is not implicated in the regulation of vimentin by SIP1. Our results therefore implicate SIP1 in the regulation of vimentin observed in the EMT associated with breast tumor cell migration, a pathway that may contribute to the metastatic progression of breast cancer.

β-Catenin and ZO-1: Shuttle Molecules Involved in Tumor Invasion-Associated Epithelial-Mesenchymal Transition Processes

The cytoplasmic/nuclear relocalization of β-catenin and ZO-1 from the adherens and tight junctions are common processes of the epithelial-mesenchymal transition (EMT) associated with tumor invasion. Data are now accumulating to demonstrate that these molecules, which shuttle between the plasma membrane and the nucleus or the cytosol, are involved in signaling pathways, and contribute to the regulation of genes such as vimentin or matrix metalloproteinase-14 which are turned on during EMT.

Absence of aromatase protein and mRNA expression in endometriosis.

BACKGROUND Aromatase has been reported to be involved in estrogen biosynthesis and expressed in eutopic and ectopic endometrium of endometriosis patients. The objective of the present study was to investigate its expression and localization in three distinct types of endometriosis. METHODS Human peritoneal, ovarian and rectovaginal endometriotic lesions and matched eutopic endometrium were collected from patients during laparoscopy. Aromatase protein localization (immunohistochemistry, n = 63) and mRNA expression [quantitative polymerase chain reaction (Q-PCR), n = 64] were assessed. RESULTS No aromatase protein was detected by immunohistochemistry in either the glandular or stromal compartment of endometriotic lesions or eutopic endometrium, while it was strong in placental syncytiotrophoblasts, granulosa and internal theca cells from pre-ovulatory follicles, and luteal cells from corpus luteum. By Q-PCR, low but discernible levels of aromatase expression were found in endometriomas, probably due to follicular expression. Transcripts for aromatase were barely detectable in only a few peritoneal and rectovaginal endometriotic lesions, and a few eutopic endometrium samples, probably due to contaminating surrounding tissues (adipose tissue, intact peritoneum). CONCLUSIONS Unlike previous studies, we observed no aromatase protein in any of the endometriosis types, and barely detectable aromatase mRNA expression, suggesting that locally produced aromatase (within endometriotic lesions) may be less implicated in endometriosis development than previously postulated. Potential factors responsible for these discrepancies are discussed.

Transactivation of MCP-1/CCL2 by beta-catenin/TCF-4 in human breast cancer cells.

The loss of E‐cadherin expression and the translocation of β‐catenin to the nucleus are frequently associated with the metastatic conversion of epithelial cells. In the nucleus, β‐catenin binds to the TCF/LEF‐1 (T‐cell factor/ lymphoid enhancer factor) transcription factor family resulting in the activation of several genes, some of them having important implications in tumour progression. In our study, we investigated the potential regulation of monocyte chemotactic protein‐1 (MCP‐1/CCL2) expression by the β‐catenin/TCF pathway. This CC‐chemokine has been implicated in tumour progression events such as angiogenesis or tumour associated macrophage (TAM) infiltration. We thus demonstrated that MCP‐1 expression correlates with the reorganization of the E‐cadherin/β‐catenin complexes. Indeed, MCP‐1 was expressed by invasive breast cancer cells (MDA‐MB‐231, BT549 and Hs578T), which do not express E‐cadherin but was not produced by noninvasive breast cancer cell lines (MCF7 and T47D) expressing high level of E‐cadherin. In addition, the MCP‐1 promoter was activated in BT549 breast cancer cells transfected with β‐catenin and TCF‐4 cDNAs. The MCP‐1 mRNA level was similarly upregulated. Moreover, we showed that MCP‐1 mRNA was downregulated after transfection with a siRNA against β‐catenin in both BT549 and Hs578T cells. Our results therefore identify MCP‐1 as a target of the β‐catenin/TCF/LEF pathway in breast tumour cells, a regulation which could play a key role in breast tumour progression.

The uterine and vascular actions of estetrol delineate a distinctive profile of estrogen receptor α modulation, uncoupling nuclear and membrane activation

Estetrol (E4) is a natural estrogen with a long half‐life produced only by the human fetal liver during pregnancy. The crystal structures of the estrogen receptor α (ERα) ligand‐binding domain bound to 17β‐estradiol (E2) and E4 are very similar, as well as their capacity to activate the two activation functions AF‐1 and AF‐2 and to recruit the coactivator SRC3. In vivo administration of high doses of E4 stimulated uterine gene expression, epithelial proliferation, and prevented atheroma, three recognized nuclear ERα actions. However, E4 failed to promote endothelial NO synthase activation and acceleration of endothelial healing, two processes clearly dependent on membrane‐initiated steroid signaling (MISS). Furthermore, E4 antagonized E2 MISS‐dependent effects in endothelium but also in MCF‐7 breast cancer cell line. This profile of ERα activation by E4, uncoupling nuclear and membrane activation, characterizes E4 as a selective ER modulator which could have medical applications that should now be considered further.

Estetrol is a weak estrogen antagonizing estradiol-dependent mammary gland proliferation

Estetrol (E4) is a natural estrogen produced exclusively by the human fetal liver during pregnancy. Its physiological activity remains unknown. In contrast to ethinyl estradiol and estradiol (E2), E4 has a minimal impact on liver cell activity and could provide a better safety profile in contraception or hormone therapy. The aim of this study was to delineate if E4 exhibits an activity profile distinct from that of E2 on mammary gland. Compared with E2, E4 acted as a low-affinity estrogen in both human in vitro and murine in vivo models. E4 was 100 times less potent than E2 to stimulate the proliferation of human breast epithelial (HBE) cells and murine mammary gland in vitro and in vivo respectively. This effect was prevented by fulvestrant and tamoxifen, supporting the notion that ERα (ESR1) is the main mediator of the estrogenic effect of E4 on the breast. Interestingly, when E4 was administered along with E2, it significantly antagonized the strong stimulatory effect of E2 on HBE cell proliferation and on the growth of mammary ducts. This study characterizes for the first time the impact of E4 on mammary gland. Our results highlight that E4 is less potent than E2 and exhibits antagonistic properties toward the proliferative effect of E2 on breast epithelial cells. These data support E4 as a potential new estrogen for clinical use with a reduced impact on breast proliferation.

Is the baboon model appropriate for endometriosis studies

OBJECTIVE To determinethe prevalence of spontaneous endometriosis andthe incidence of induced endometriosis after endocervical canal resection in baboons. DESIGN Induction and follow-up of endometriosis in baboons, which is one of the primate species that develop spontaneous endometriosis. Forty-one baboons were checked for the presence of spontaneous endometriosis. We then attempted to induce endometriosis in 30 of them by endocervical canal resection. SETTING Institute of Primate Research, Nairobi, Kenya, and Catholic University of Louvain, Brussels, Belgium. ANIMAL(S) Forty-one baboons were checked for spontaneous endometriosis and 30 of them were used to develop a model of induced endometriosis. INTERVENTION(S) A total of 41 baboons underwent diagnostic laparoscopy for 10 months. In a first step, 30 of this number subsequently underwent endocervical canal resection. In a second step, 20 of the 30 underwent uterine horn resection. MAIN OUTCOME MEASURE(S) Follow-up by laparoscopy. RESULT(S) Two of the 41 baboons were diagnosed with spontaneous endometriosis (4.8%). Twelve months after the surgical procedure to induce endometriosis, 8 of 29 animals presented with endometriotic lesions diagnosed by using laparoscopy and confirmed by histologic examination. The incidence of induced endometriosis in our model was thus 27.6%. In 2 baboons, endometriosis disappeared over time, resulting in a final rate of 20.7% (6/29). CONCLUSION(S) The rate of spontaneous endometriosis is very low (4.8%). Endometriosis can be induced (with a rate of just 27.6%) by endocervical canal resection to stimulate retrograde menstruation.

Regulation of CXCL8/IL-8 expression by Zonula Occludens-1 in human breast cancer cells.

Accumulating data now suggest that ZO-1, once delocalized from tight junctions, could be implicated in the regulation of tumor-promoting genes. Because of their major implication in different steps of tumor progression, we investigated here the influence of ZO-1 on chemokines expression in breast cancer cells. Using GeneArray analysis to compare chemokine mRNA expression in breast tumor cells transfected with a siRNA against ZO-1, we identified CXCL-8IL-8 as a major potential target of ZO-1 signaling, being strongly downregulated following ZO-1 siRNA transfection. Examining further the relationship between ZO-1 and interleukin-8 (CXCL8/IL-8), we first showed that CXCL8/IL-8 expression correlates with a relocalization of ZO-1 in several breast cancer cell lines. Moreover, CXCL8/IL-8 is downregulated in invasive BT549 cells transfected with three different ZO-1 siRNA and overexpressed in noninvasive BT20 and SKBR3 cells transfected with vectors expressing ZO-1. We also provide evidence for an activation of the CXCL8/IL-8 promoter by ZO-1. Finally, we show that the regulation of CXCL8/IL-8 by ZO-1 is independent of the β-catenin pathway. Our results thus clearly show an implication of ZO-1 in CXCL8/IL-8 regulation. Because of the major implications of CXCL8/IL-8 in tumor invasion, such a regulation could play an important role in breast cancer progression. Mol Cancer Res; 10(1); 121–32. ©2011 AACR.

Device-based controlled local delivery of anastrozol into peritoneal cavity: In vitro and in vivo evaluation

Local treatment using drug loaded implants allows decreasing seric concentrations of the active ingredient with the purpose of limiting side effects and reaching perfect observance. Nowadays, some diseases are already treated with implants, but generally, by subcutaneous or intra vaginal implantation. In this work, a new implant device dedicated to the intra-peritoneal cavity was developed. For this purpose, a core-membrane polymer implant was selected. We propose an original method to determine the most appropriate membrane to control the release based on the use of Franz cells. The ability of the implant to release a constant quantity of an active ingredient will be assessed by testing implants in vitro. Finally, intra peritoneal cavity and subcutaneous in vivo implantation has been achieved in order to confirm the controlled and local release of the active ingredient.