Biomedical subjects

D Thibout

Publications and source records attributed to D Thibout.

4 recordsLinked to original sources

PubMed2001

Decrease of breast cancer cell invasiveness by sodium phenylacetate (NaPa) is associated with an increased expression of adhesive molecules.

Sodium phenylacetate (NaPa), a non-toxic phenylalanine metabolite, has been shown to induce in vivo and in vitro cytostatic and antiproliferative effects on various cell types. In this work, we analysed the effect of NaPa on the invasiveness of breast cancer cell (MDA-MB-231, MCF-7 and MCF-7 ras). Using the highly invasive breast cancer cell line MDA-MB-231, we demonstrated that an 18-hour incubation with NaPa strongly inhibits the cell invasiveness through Matrigel (86% inhibition at 20 mM of NaPa). As cell invasiveness is greatly influenced by the expression of urokinase (u-PA) and its cell surface receptor (u-PAR) as well as the secretion of matrix metalloproteinases (MMP), we tested the effect of NaPa on these parameters. An 18-hour incubation with NaPa did not modify u-PA expression, either on MDA-MB-231 or on MCF-7 and MCF-7 ras cell lines, and induced a small u-PA decrease after 3 days of treatment of MDA-MB-321 with NaPa. In contrast, an 18 h incubation of MDA-MB-231 increased the expression of u-PAR and the secretion of MMP-9. As u-PAR is a ligand for vitronectin, a composant of the extracellular matrix, these data could explain the increased adhesion of MDA-MB-231 to vitronectin, while cell adhesivity of MCF-7 and MCF-7 ras was unmodified by NaPa treatment. NaPa induced also an increased expression of both Lymphocyte Function-Associated-1 (LFA-1) and Intercellular Adhesion Molecule-1 (ICAM-1), which was obvious from 18 hour incubation with NaPa for the MDA-MB-231 cells, but was delayed (3 days) for MCF-7 and MCF-7 ras. Only neutralizing antibodies against LFA-1 reversed the decreased invasiveness of NaPa-treated cells. Therefore we can conclude that the strong inhibition of MDA-MB-231 invasiveness is not due to a decrease in proteases involved in cell migration (u-PA and MMP) but could be related both to the modification of cell structure and an increased expression of adhesion molecules such as u-PAR and LFA-1.

Antineoplastic Agents↗

PubMed1997

Characterization of a new BLM mutation associated with a topoisomerase II alpha defect in a patient with Bloom's syndrome.

Bloom's syndrome (BS), a human recessive disorder associated with an increased risk of malignancy, arises through mutations in both alleles of the BLM gene, which was recently identified as a member of the RecQ helicase family. BS cells are characterized by an increased rate of sister chromatid exchange (SCE). However, a subpopulation of lymphocytes exhibiting a normal level of SCE is observed in some patients. It has been proposed that reversion to a low-SCE phenotype involves an intragenic crossing over between the paternal and maternal BLM alleles, generating a wild-type allele. In this study we characterize a new BLM mutation in a BS patient leading to the replacement, in the C-terminal region of Blm, of a highly conserved cysteine by a phenylalanine in codon 1036. Moreover, our data show that this patient also inherited a BLM allele carrying a mutation affecting its expression and that a somatic intragenic crossing over was involved in reversion to the low-SCE phenotype. Further, we show that both topoisomerase II alpha mRNA and protein levels are decreased in the high-SCE cells derived from this patient, whereas they are normal in the corresponding low-SCE cells. Altogether, our data led us to propose that besides its putative helicase activity, Blm could be involved in transcription regulation.

Adenosine Triphosphatases↗

PubMedDate not supplied

Sodium phenylacetate (NaPa) induces modifications of the proliferation, the adhesion and the cell cycle of tumoral epithelial breast cells.

Sodium phenylacetate (NaPa), a physiological product of phenylalanine metabolism, present in micromolar concentrations in human plasma, has been shown to induce in vivo and in vitro cytostatic antiproliferative effects at millimolar concentrations. Cadherin molecules are powerful invasion suppressor molecules and the reduction of E-cadherin expression plays an important role in the invasion and metastasis of human breast cancer. In this study, we demonstrated, on one hand, that NaPa stimulated aggregation by increasing the expression of E-cadherin at the surface of breast cancer MCF-7ras cells transformed by Ha-ras oncogene and inhibited its expression in MCF-7 cells. We demonstrated that NaPa increased the formation of MCF-7ras cell aggregates and did not alter the formation of MCF-7 cell aggregates. By Northern blot, we demonstrated that the E-cadherin expression was not regulated at the transcriptional level. On the other hand, we analyzed the cell cycle of these 2 cell lines after NaPa treatment and showed that NaPa induced arrest at the G1/S phase in both MCF-7 and MCF-7ras cells. bFGF increased the growth of MCF-7 cells, but inhibited MCF-7ras cell proliferation. NaPa treatment suppressed the stimulation of MCF-7 cell proliferation and increased MCF-7ras cell growth inhibition. We have demonstrated a new target of NaPa action in blocking the cell cycle of tumor cells in G0/G1. We suggest that the anti-proliferative effect of NaPa associated to the restoration of the cadherin function in human mammary carcinoma cells indicates that NaPa could be a novel therapeutic agent in breast cancer.

Adenocarcinoma↗

PubMedDate not supplied

Sodium phenylacetate modulates the synthesis of autocrine and paracrine growth factors secreted by breast cancer cell lines.

Sodium Phenylacetate (NaPq) has been shown to suppress tumor growth and promote differentiation in experimental models. Thus, we have previously shown an inhibition of MCF-7ras cell proliferation by NaPa both in vitro and in vivo on xenographed tumors. In order to study the action of NaPa on the synthesis of paracrine or autocrine growth factors, conditioned media were prepared from breast pretumoral HBL100 cells, tumoral MCF-7 and MCF-7ras cells in the presence of NaPa. Growth factor activities of these media were tested on Balb c/3T3 fibroblasts and on the above breast tumor cells. Conditioned media from the 3 cell types contained different mitogenic activities when tested on the same cell lines. NaPa treatment for 24 hours inhibited differentially and dose-dependently the mitogenic activity of conditioned media. Inhibitions of HBL100 and MCF-7 cell proliferation by MCF-7ras medium conditioned with 20 mM NaPa reached 75% and 48% respectively. In contrast, NaPa treated MCF-7 conditioned medium decreased HBL100 and MCF-7ras proliferation by 49% and 72%, respectively, at the same NaPa concentration. The efficiency of NaPa inhibition reached an optimum as soon as one day after treatment. Among growth factors secreted by MCF-7 and MCF-7ras, TGF beta synthesis is inhibited and stimulated in MCF-7 and MCF-7ras cells respectively after NaPa treatment. We showed that NaPa modifies the synthesis of growth factors secreted by MCF-7 and MCF-7ras tumor cells leading to cell proliferation inhibitions. The synthesis of these previously identified factors was more involved in MCF-7 cells than fibroblast cell proliferation. In vitro and in vivo NaPa inhibition of MCF-7ras cells which secreted higher levels of these growth factors could be explained by this mechanism of action.

3T3 Cells↗