C. M. Lapiere

Enhancement of tumorigenicity of human breast adenocarcinoma cells in nude mice by matrigel and fibroblasts.

The failure of MCF7 cells to induce the formation of tumours after sub-cutaneous inoculation into athymic nude mice can be obviated by the simultaneous injection of an extract of basement membrane proteins (matrigel). Tumour growth is promoted and the latency period is low (2 to 4 weeks). In the absence of matrigel, the simultaneous inoculation of fibroblasts and MCF7 cells also resulted in the development of tumours, but with a longer latency period (about 2 months). The tumorigenic synergy between matrigel and fibroblasts was evidenced by co-inoculating MCF7 cells MDA-MB 231 cells with fibroblasts and matrigel. This co-inoculation decreased the delay of appearance of the tumours and/or accelerated the tumour growth, depending upon the number of fibroblasts injected. Repeated injections of fibroblasts conditioned medium, at the site of inoculum of tumour cells also enhanced tumour growth, suggesting the involvement of soluble factors secreted by fibroblasts. Histologically, tumours induced by co-inoculation of tumour cells and fibroblasts contained more stromal structures including vimentin-positive cells, fibronectin and interstitial collagens. These data suggest that human tumours may be reconstituted and grown in athymic nude mice using basement membrane components and fibroblasts as inductors.

ADAMTS-2 functions as anti-angiogenic and anti-tumoral molecule independently of its catalytic activity

ADAMTS-2 is a metalloproteinase that plays a key role in the processing of fibrillar procollagen precursors into mature collagen molecules by excising the amino-propeptide. We demonstrate that recombinant ADAMTS-2 is also able to reduce proliferation of endothelial cells, and to induce their retraction and detachment from the substrate resulting in apoptosis. Dephosphorylation of Erk1/2 and MLC largely precedes the ADAMTS-2 induced morphological alterations. In 3-D culture models, ADAMTS-2 strongly reduced branching of capillary-like structures formed by endothelial cells and their long-term maintenance and inhibited vessels formation in embryoid bodies (EB). Growth and vascularization of tumors formed in nude mice by HEK 293-EBNA cells expressing ADAMTS-2 were drastically reduced. A similar anti-tumoral activity was observed when using cells expressing recombinant deleted forms of ADAMTS-2, including catalytically inactive enzyme. Nucleolin, a nuclear protein also found to be associated with the cell membrane, was identified as a potential receptor mediating the antiangiogenic properties of ADAMTS-2.

Primary sarcoma of an abdominal aortic aneurysm

Primary tumors of the aorta are extremely rare and the diagnosis is made most often after surgery or autopsy. Because clinical symptoms of abdominal sarcoma are similar to those of occlusive or aneurysmal disease, aortic sarcomas are frequently mistaken for these lesions. The imaging findings are frequently nonspecific and therefore do not allow a definitive preoperative diagnosis. We report a case of an epithelioid angiosarcoma in the vessel wall of an abdominal aortic aneurysm.

Investigation of the relationship between osteoporosis and the collagenase gene by means of polymorphism of the 5′upstream region of this gene

Osteoporosis is a slowly progressing disease resulting from an imbalance between bone accretion and degradation. As interstitial collagenase is a key enzyme in the degradatior of bone matrix, we investigated a possible relationship between the collagenase gene and osteoporosis. Analysis of an amplified genomic DNA fragment from-524 to +52 by denaturing gradient gel electrophoresis and sequencing allowed us to detect three dimorphic sites upstream of base-300, one of them leading to a BanI restriction site. None of the sites could be directly associated with osteoporosis. The allele frequencies of the three dimorphic sites were estimated. The interallelic ratios were high, thus providing new useful genetic markers for linkage analysis. When comparing these ratios in osteoporotic and nonosteoporotic subjects, no significant differences could be observed.

Establishment of stable human fibroblast cell lines constitutively expressing active Rho-GTPases

Summary.Small GTP-binding proteins of the Rho family (RhoA, Cdc42, Rac1) regulate the organisation and the turnover of the cell’s cytoskeleton and adhesion structures. A significant function of these cellular structures is to translate and counterbalance forces applied to, or generated by, cells in order to maintain homeostasis and control cell movement. We therefore hypothesised that Rho-GTPases are directly involved in cellular gravity perception and may participate in the alterations induced in microgravity. To define an adequate cellular model allowing to investigate this issue, we have established stable cell lines constitutively expressing active forms of either RhoA, Cdc42, or Rac1. The three cell lines differ by morphology and by their ability to form filopodia, lamellipodia, and bundles of actin stress fibers. Overexpression of the active form of either RhoA, Cdc42, or Rac1 is compatible with cell viability and does not affect cell population doubling time. Thus, our series of mutant cells appear well suited to gain further knowledge on the molecular mechanisms of cellular gravity perception.

Increased Mrna Expression of Decorin in the Prolapsing Posterior Leaflet of the Mitral Valve

To improve our understanding of myxomatous degeneration of the valvar tissue as seen in mitral valve prolapse, we have compared the biosynthetic phenotype of the connective tissue cells in myxomatous segments (n=4) resected during surgery with that of homologous segments of normal valves (n=4) harvested in age-matched organ donors. The steady-state level of mRNA for selected extracellular matrix macromolecules and metalloproteinases was assessed by quantitative (internal standard controlled) reverse transcriptase-polymerase chain reaction (RT-PCR). Among the investigated gene products, the decorin mRNA expression was significantly increased in degenerative valve compared with normal tissue (211+/-48 vs. 100+/-70, p<0.02). The level of fibrillin 2 also tended to be increased (194+/-88 vs. 100+/-81, p=0.08). These results suggest that myxomatous valvar tissue is characterized by an overexpression of mRNA for decorin. Owing to the role of this small leucine-rich proteoglycan in the regulation of fibril assembly and stability, this alteration may account for or is a result of a defective organization of the collagen and elastic fibers in this disease and contribute to the intrinsic distensibility and fragility of the myxomatous tissue.

Signaling through Rho GTPases in microgravity (Rho signaling) on ISS (Soyuz TMA-1) Belgian Soyuz Mission "Odissea"

Rho GTPases, RhoA, Rac1 and Cdc42, are molecular switches in the intracellular signaling pathways, that relay the information collected by receptors to soluble mediators and insoluble extracellular matrix environment. The objective of this experiment was to investigate the impact of microgravity on cellular processes depending on Rho GTPases activity, i.e.cytoskeleton and focal adhesions organization, GTPases translocation to the membrane, nuclear translocation of signaling molecules and gene expression. WI26 fibroblasts were stably transfected by the constitutively active form of each of the Rho GTPase. Selected clone of the engineered cells and the wild-type cells were used during the belgian ODISSEA Soyuz mission to investigate the alterations of the mechanical and phenotypic expression of the cells induced by microgravity and their rescue by the engineered Rho GTPases. A failure in the time schedule, a disconnection of the experiment containers before the automatic activation of the fixation procedure, was responsible for the loss of the biological samples.

High-Grade Pleomorphic T Cell Lymphoma with Restricted Involvement of Skin and Bone Marrow

Pleomorphic T cell lymphoma of the medium to large cell type expressing CD30 antigen is a most aggressive peripheral T cell lymphoma. Currently, there is no satisfactory treatment available for this neoplasm. We report the case of a woman with prominent skin and bone marrow involvement without detectable lymph node localization. This unusual presentation of disease responded well to polychemotherapy combined with autologous bone marrow transplantation.

Effect of Pregnancy on the Biosynthesis of Collagen and Proteoglycan by Normotensive or Hypertensive Rat Aortas

The rates of biosynthesis of collagen and glycosaminoglycan were reduced in aortas of normotensive pregnant rats as compared with those of non pregnant animals of the same age. Induction of renal hypertension caused a two to three fold increase in the synthesis of aortic collagen and glycosaminoglycan in non pregnant as well as in pregnant rats. The activities of prolyl-4-hydroxylase and galactosylhydroxylysyl-glucosyltransferase, two intracellular enzymes of collagen synthesis, exhibited changes which paralleled those of collagen synthesis. Prolyl-4-hydroxylase was localized predominantly to the aortic smooth muscle cells indicating that these cells are responsible for the deposition of collagen in normal and hypertensive arteries. No shift of types I and III collagen synthesis was observed during pregnancy or in the early phases of induced renal hypertension.