Biomedical subjects

Agnès Legrand

Publications and source records attributed to Agnès Legrand.

6 recordsLinked to original sources

PubMed2007

Cartography of gene expression in CD8 single cells: novel CCR7- subsets suggest differentiation independent of CD45RA expression.

Understanding the distribution, function, and lineage relationship of CD8+ T-cell subpopulations is of fundamental value for the monitoring of the immune system in several experimental and clinical situations. However, the available data concerning the description of effector and memory CD8+ subsets in humans remain rather fragmentary because different studies favored the usage of distinct and restricted sets of cell surface markers and functional parameters. We associated multiple markers to subdivide CD8+ T cells into 14 different cell types, several of which were not described previously, and evaluated the coexpression of 18 genes simultaneously in individual cells from each subset. Our results show that each subset has a defined pattern of gene expression. Moreover, effector gene expression of CCR7- cells correlated only with CD27 expression levels and CD27/CD28 coexpression but not with CD45RA/R0 phenotypes. Our findings thus describe new CD8+ cell subsets, allow the identification of relatively homogeneous CD8+ subpopulations, provide a predictable and precise correlation between particular cell surface markers and CD8+ T-cell functional properties, and identify effector cells present in both CCR7-CD45RA+ and CCR7-CD45R0+ compartments. The results also indicate that activated cells might modulate the expression of CD45RA/R0 asynchronously rather than CCR7-CD45RA+ cells always issuing from CD45RA- precursors.

Adult↗

PubMed2006

Partial Beclin 1 silencing aggravates doxorubicin- and Fas-induced apoptosis in HepG2 cells.

AIM: To investigate the role of Beclin 1 on the susceptibility of HepG2 cells to undergo apoptosis after anti-Fas antibody or doxorubicin treatment. METHODS: Beclin 1 silencing was achieved using RNA interference. DNA ploidy, the percentage of apoptotic cells and the mitochondrial membrane potential were assessed by flow cytometry. Levels of Beclin 1, Bcl-X(L) and cytochrome c, and the cleavage of poly (ADP-ribose) polymerase (PARP) were assayed by using Western blots. RESULTS: Beclin 1 expression decreased by 75% 72 h after Beclin 1 siRNA transfection. Partial Beclin 1 silencing significantly increased the percentage of subG1 cells 24 and 40 h after treatment with doxorubicin or anti-Fas antibody, respectively, and this potentiation was abrogated by treatment with a pan-caspase inhibitor. Partial Beclin 1 silencing also increased PARP cleavage, mitochondrial membrane depolarization and cytosolic cytochrome c. The pro-apoptotic consequences of partial Beclin 1 silencing were not associated with a decline in Bcl-X(L) expression. CONCLUSION: Partial Beclin 1 silencing aggravates mitochondrial permeabilization and apoptosis in HepG2 cells treated with an anti-Fas antibody or with doxorubicin.

Antibiotics, Antineoplastic↗

PubMed2005

Keratinocyte growth factor expression by fibroblasts in pulmonary fibrosis: poor response to interleukin-1beta.

Keratinocyte growth factor (KGF) is secreted by fibroblasts and protects from pulmonary fibrosis in animal models. Interleukin (IL)-1beta is the most potent inducer of KGF in fibroblasts, acting through the c-Jun pathway. We evaluated in vitro KGF production by human lung fibroblasts from patients with idiopathic pulmonary fibrosis (IPF, n = 10) and from control subjects (n = 7) at baseline and after IL-1beta stimulation. Basal KGF secretion by IPF fibroblasts was similar to controls. In fibroblasts from control subjects, IL-1beta increased c-Jun expression, c-Jun activation, and KGF secretion. SP600125, a specific c-Jun N-terminal kinase (JNK) inhibitor, inhibited the effect of IL-1beta. By contrast, in IPF fibroblasts, IL-1beta did not increase c-Jun expression and c-Jun activation, and weakly increased KGF secretion, whereas SP600125 had no effect. IL-1beta similarly increased JunB expression in fibroblasts from patients with IPF and control subjects. Total JNK content was not different in either unstimulated or IL-1beta-stimulated IPF and control fibroblasts. IL-1beta increased phosphorylated JNK in control and IPF fibroblasts, but this increase was weaker and heterogeneous in IPF. Altogether, our results demonstrate a dysregulation of KGF secretion by IPF fibroblasts. The weak response to IL-1beta is associated with a defect of c-Jun expression and activation and a defect of JNK activation.

Adult↗

PubMed2004

Differential response of p53 target genes to p73 overexpression in SH-SY5Y neuroblastoma cell line.

p73, the first p53 gene homologue, encodes an array of p73 proteins including p73 alpha full-length (TAp73 alpha) and amino-truncated isoforms (Delta Np73 alpha), two proteins with opposite biological functions. TAp73 alpha can induce tumor suppressive properties, while Delta Np73 alpha antagonizes p53 as well as TAp73 in a dominant-negative manner. In human malignant neuroblasts, p53 protein is wild-type but known to be excluded from the nucleus, therefore disabling its function as a tumor suppressor. The present study investigates whether there is a functional link between p73 isoforms and p53 in neuroblastoma. Experiments were performed on two neuroblastoma cell lines differing in their p53 status, e.g. wild-type p53 SH-5Y5Y cells and mutated p53 IGR-N-91 cells. Data indicate that (i) both TA- and Delta N-p73 alpha enhance p53 protein level in SH-SY5Y cells, whereas level remains unchanged in IGR-N-91 cells; (ii) only in SH-SY5Y cells does forced TAp73 alpha overexpression markedly induce nuclear accumulation of p53 protein; (iii) p21 protein expression is increased in both cell lines infected with TAp73, suggesting that, in IGR-N-91 cells, p21 is induced by p73 through a p53-independent pathway; (iv) in the SHSY5Y cell line, Btg2 expression is strongly enhanced in cells overexpressing TA, and to a lesser extent in cells overexpressing Delta N. Taken together our results suggest that TAp73 may restore p53 function in NB with wild-type nonfunctional p53, but not in NB with mutated p53.

Cell Differentiation↗

PubMed2002

Activation of NF-kappa B, AP-1 and STAT transcription factors is a frequent and early event in human hepatocellular carcinomas.

BACKGROUND/AIMS: Hepatitis B and C viruses, two inducers of hepatocarcinomas, have been shown to activate AP-1, NF-kappa B and STAT in vitro, but no detailed information on the activity of these transcription factors in vivo have been provided. METHODS: We have measured the DNA binding activity of these transcription factors in the peri-tumoral and the tumoral parts of 15 primary liver cancers, of viral or non-viral etiologies, and in five hepatic metastases using electrophoretic mobility shift assays. RESULTS: AP-1, NF-kappa B and STAT binding activities were increased in the peritumoral tissue, compared with histologically normal livers in 73, 87 and 70%, respectively, of the cases. A further activation of AP-1, NF-kappa B, but not STAT binding in the tumoral parts was detected in 40 and 80%, respectively, of the cases. A close correlation was found between JunD and c-Jun levels and AP-1 binding activity at the tumoral stage. By contrast, AP-1 and NF-kappa B binding activities were low or only slightly elevated in the peri-tumoral and the tumoral tissue of metastases. CONCLUSIONS: Early activation of AP-1, NF-kappa B and STAT contributes probably to the acquisition of a transformed phenotype during hepatocarcinogenesis, whatever the etiology.

Carcinoma, Hepatocellular↗

PubMedDate not supplied

Progesterone induces BRCA1 mRNA decrease, cell cycle alterations and apoptosis in the MCF7 breast cancer cell line.

BACKGROUND: Inherited mutations of the BRCA1 gene are responsible for hereditary breast and ovarian cancer syndrome. However, little is known of how disruption of BRCA1 functions preferentially increases cancer risk in hormone-dependent organs. We aimed to study whether BRCA1 was regulated by progesterone in the MCF7 breast cancer cell line. MATERIALS AND METHODS: MCF7 breast cancer cells were incubated with 10(-4) or 10(-10) M progesterone for 24 or 48 hours. BRCA1 expression, proliferation and apoptosis were analysed. RESULTS: 10(-4) M progesterone decreased cell proliferation, cell cycle progression and induced apoptosis. In addition, BRCA1 and cyclin A mRNA decreased. In contrast, none of these effects were observed in MCF7 cells incubated with 10(-10) M progesterone. CONCLUSION: The down-regulation of BRCA1 in MCF7 cells incubated with 10(-4) M progesterone seems to be a consequence of cell cycle alterations rather than a direct effect of the hormone on BRCA1.

Apoptosis↗