Induction of Endothelial Cell Apoptosis by Solid Tumor Cells

The mechanisms by which tumor cells extravasate to form metastasis remain controversial. Previous studies performed in vivo and in vitro demonstrate that the contact between tumor cells and the vascular wall impairs endothelium integrity. Here, we investigated the effect of breast adenocarcinoma MCF-7 cells on the apoptosis of human umbilical vein endothelial cells (HUVEC). TUNEL labeling, nuclear morphology, and DNA electrophoresis indicated that MCF-7 cells induced a two- to fourfold increase in HUVEC apoptosis. Caspase-3 activity was significantly enhanced. Neither normal cells tested (mammary epithelial cells, fibroblasts, leukocytes) nor transformed hematopoietic cells tested (HL60, Jurkat) induced HUVEC apoptosis. On the contrary, cells derived from solid tumors (breast adenocarcinoma, MDA-MB-231 and T47D; fibrosarcoma, HT 1080) had an effect similar to that of MCF-7 cells. The induction of apoptosis requires cell-to-cell contact, since it could not be reproduced by media conditioned by MCF-7 cells cultured alone or cocultured with HUVEC. Our results suggest that cells derived from solid tumors may alter the endothelium integrity by inducing endothelial cell apoptosis. On the contrary, normal or malignant leukocytes appear to extravasate by distinct mechanisms and do not damage the endothelium. Our data may lead to a better understanding of the steps involved in tumor cell extravasation

What Is the Interest of Klinefelter's Syndrome for (Child) Psychiatrists?

peer reviewedÀ partir de la prise en charge psychiatrique et endocrinologique à l'âge de 22 ans d'un patient atteint d'un trouble schizoaffectif et d'un syndrome de Klinefelter (SK), nous présentons les aspects psychopathologiques de ce syndrome qui est fréquent (près d'un garçon sur 500 à la naissance) et dont, le plus souvent, le diagnostic n'est pas posé. Les garçons atteints de ce syndrome ont généralement un retard d'acquisition du langage, un QI verbal inférieur à la moyenne et un QI global dans les limites de la normale. Sans suivi spécifique, le risque de troubles psychiatriques (de tous types) est plus élevé que celui de la population générale, comme le prouvent des études réalisées en milieu psychiatrique. En cas d'hypotestostéronémie (très fréquente), un traitement substitutif par undécanoate de testostérone devrait être instauré (idéalement entre 11 et 15 ans, mais le diagnostic est souvent posé à l'âge adulte) pour ses effets bénéfiques somatiques et psychiques. Jusqu'à présent, aucune donnée fiable dans la littérature ne contre-indique formellement un traitement par androgènes en cas de trouble psychiatrique grave. Cependant, chaque situation devra être évaluée attentivement ; l'éventuelle androgénothérapie doit être intro­ duite progressivement et sera associée à une évaluation psychiatrique très régulière

A Heterogeneous In Vitro Three Dimensional Model of Tumour-Stroma Interactions Regulating Sprouting Angiogenesis

Angiogenesis, the formation of new blood vessels, is an essential process for tumour progression and is an area of significant therapeutic interest. Different in vitro systems and more complex in vivo systems have been described for the study of tumour angiogenesis. However, there are few human 3D in vitro systems described to date which mimic the cellular heterogeneity and complexity of angiogenesis within the tumour microenvironment. In this study we describe the Minitumour model – a 3 dimensional human spheroid-based system consisting of endothelial cells and fibroblasts in co-culture with the breast cancer cell line MDA-MB-231, for the study of tumour angiogenesis in vitro. After implantation in collagen-I gels, Minitumour spheroids form quantifiable endothelial capillary-like structures. The endothelial cell pre-capillary sprouts are supported by the fibroblasts, which act as mural cells, and their growth is increased by the presence of cancer cells. Characterisation of the Minitumour model using small molecule inhibitors and inhibitory antibodies show that endothelial sprout formation is dependent on growth factors and cytokines known to be important for tumour angiogenesis. The model also shows a response to anti-angiogenic agents similar to previously described in vivo data. We demonstrate that independent manipulation of the different cell types is possible, using common molecular techniques, before incorporation into the model. This aspect of Minitumour spheroid analysis makes this model ideal for high content studies of gene function in individual cell types, allowing for the dissection of their roles in cell-cell interactions. Finally, using this technique, we were able to show the requirement of the metalloproteinase MT1-MMP in endothelial cells and fibroblasts, but not cancer cells, for sprouting angiogenesis

Demonstration in Vivo That Stromelysin-3 Functions through Its Proteolytic Activity

Stromelysin-3 (ST3), a matrix metalloproteinase (MMP) expressed in aggressive carcinomas, has been shown to promote tumor development in different in vivo experimental models. However, the inability of its mature form to degrade extracellular matrix components casts doubt on whether ST3 functions in vivo as a protease. In this study, we evaluated whether the ST3 tumor-promoting effect could be ascribed to its proteolytic activity and whether this putative protease could be targeted with MMP inhibitors. Catalytically inactive mutant cDNA of human (h) ST3 or mouse (m) ST3 were generated and transfected into MCF7 cells. When injected into nude mice in the presence of matrigel, the mutant-bearing cells did not exhibit the enhanced tumorigenicity elicited by MCF7 cells transfected with wild-type ST3 cDNA. In a second approach, TIMP2 overproduction in MCF7 cells expressing hST3 was induced by retroviral infection. The co-expression of ST3 and TIMP2 failed to enhance the tumorigenicity of MCF7 cells. Notably, matrigel depleted of low-molecular-weight proteins and growth factors failed to promote the tumorigenicity of ST3-expressing MCF7 cells. These findings provide the first in vivo evidence that ST3 is indeed a protease that can modulate cancer progression by remodeling extracellular matrix and probably by inducing it to release the necessary microenvironmental factors. Thus, ST3 represents an interesting target for specific MMP inhibition

L’apoptose mammaire dans le sein normal et en pathologie

peer reviewe

Effects of a progestogen on normal human breast epithelial cell apoptosis in vitro and in vivo

peer reviewedMany investigators have reported cyclic proliferation of normal human breast epithelial cells. A delicate balance between proliferation and apoptosis (programmed cell death) ensures breast homeostasis. Both the follicular and luteal phases of the menstrual cycle are characterized by proliferation, whereas apoptosis occurs only at the end of the latter phase. In this study, we observed that the withdrawal of a synthetic progestin (nomegestrol acetate or NOMAC), but not continuous treatment with it, induced apoptosis of normal human breast epithelial cells in vitro and in women who applied NOMAC gel to their breasts. Furthermore, this apoptotic response was specific to normal breast cells, since withdrawal of NOMAC did not induce apoptosis of tumoral T47D cells in vitro or of fibroadenoma cells in women. These observations open up new perspectives in the prevention of hyperplasia and breast cancer. (C) 2003 Elsevier Science Ltd. All rights reserved

Influence du régime d’administration continu ou discontinu d’acétate de nomégestrol sur l’apoptose des cellules mammaires

peer reviewe

Emerging Roles for Proteinases in Cancer

Metalloproteinases and serine proteinases have been associated with tumor invasion and formation of metastasis which represent the major obstacles to cancer cure. The contribution of proteinases in these processes was initially thought to be the destruction of extracellular matrices. However, recent evidence suggests that they mainly affect tumor growth rather than invasion. Proteinases can indeed generate active matrix protein fragments, influence the release, the activation and the bioavailability of growth factors, and consequently modulate tumor cell growth, apoptosis and angiogenesis. Additionally, proteinases, their receptors and/or inhibitors can be directly involved in cell migration and in the processing or shedding of cell surface proteins. Further elucidation of the functions of proteinases is essential for the development of novel anticancer strategies

Progesterone Receptor Activation. An Alternative to SERMs in Breast Cancer

Data regarding the effects of progesterone and a progestagen on human normal breast epithelial cell proliferation and apoptosis are presented here. In postmenopausal women, adding progesterone to percutaneously administrated oestradiol significantly reduces the proliferation induced by oestradiol. In vitro and in premenopausal women, stopping the administration of nomegestrol acetate triggers a peak of apoptosis. Fibro-adenoma and cancerous cells do not show this regulation of apoptosis. Progesterone seems to be important in normal breast homeostasis