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ABSTRACT: Epigenetic modifications commonly associated with tumor development, such as histone deacetylation, may influence the resistance of some tumor cells to tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) by regulating gene transcription of components of the TRAIL signalling pathway. In the present study we have analyzed the effect of six different histone deacetylase inhibitors (HDACi), belonging to the four classic structural families, on TRAIL-induced apoptosis in leukemic T cell lines. Non-toxic and functional doses of all HDACi but apicidin, similarly sensitized different leukemic T cell lines to TRAIL-induced apoptosis, while they showed no effect on the resistance of normal T lymphocytes. Sensitizing doses of vorinostat, valproic acid, sodium butyrate and MS-275 regulated the expression of TRAIL-R2, c-FLIP and Apaf-1 in leukemic cells while TSA modulated only the expression of Apaf-1. The synergistic effect of all HDACi and TRAIL was inhibited in Bcl-2-overexpressing leukemic T cells. Thus, different HDACi may affect the expression of different TRAIL-related genes, but regulation of the mitochondrial pathway seems to be essential for the TRAIL sensitizing effect of HDACi in leukemic T cells. Overall, HDACi represent a promising and safe strategy in combination with TRAIL for treatment of T-cell leukaemia.
Cancer letters 11/2010; 297(1):91-100. · 4.86 Impact Factor
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ABSTRACT: To determine if fetal-placental hypoxia is a primary outcome of defective spiral artery remodeling.
Pregnancies in Rag2(-/-)Il2rg(-/-) double knock-out mice, which fail to undergo normal physiological spiral arterial remodeling, were compared to syngeneic BALB/c control pregnancies. Mice at gestation day (gd)6, 8, 10, 12 and 18 were infused with Hypoxyprobe-1 before euthanasia to enable detection of cellular hypoxia by immunohistochemistry.
In implantation sites of both phenotypes, trophoblast cells were reactive to Hypoxyprobe-1. No major differences were observed between the phenotypes in decidua or placenta at any gd or in gd18 fetal brain, lung, heart, liver or intestine or in maternal heart, brain, liver or spleen. Maternal kidneys from BALB/c were significantly hypoxic to Rag2(-/-)Il2rg(-/-) kidneys.
In mice, lack of pregnancy-associated spiral artery remodeling does not impair oxygen delivery to the conceptus, challenging the concept that deficient spiral arterial remodeling leads to fetal hypoxia in human gestational complications such as preeclampsia and fetal growth restriction. The isolated hypoxic response of normal kidney has revealed that renal lymphocytes may have unique, tissue-specific regulatory actions on vasoconstriction that are pregnancy independent.
Placenta 08/2010; 31(8):731-7. · 3.69 Impact Factor
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ABSTRACT: Wingless-type mouse mammary tumor virus integration site family, member 5A (WNT5A), is expressed in mouse decidua and is thought to play an important role in decidualization. We examined expression of the receptor for WNT5A, receptor tyrosine kinase-like orphan receptor 2 (ROR2), in the uteri of cycling and pregnant mice.
Reverse transcription (RT)-PCR and immunohistochemistry were performed.
RT-PCR revealed that transcripts for Ror2, Wnt3a, Wnt5a and inhibitor of WNT signaling, Dickkopf homolog 1 (Dkk1), were present in the pregnant uterus. Immunohistochemistry revealed that in the virgin uterus, ROR2 is expressed in stromal cells and on the basal side of uterine gland and endometrial epithelial cells. During pregnancy, both the luminal and basal side of uterine gland epithelial cells expressed ROR2, stromal cell expression of ROR2 became more frequent and ROR2 expressing uterine Natural Killer (NK) cells and cells lining the maternal vascular space emerged. Immunofluorescence imaging and flow cytometry revealed that although uterine NK cells expressed ROR2, NK cells of the spleen were ROR2 negative.
The expression of ROR2 by endometrial epithelial cells may suggest WNT signaling has roles in uterine epithelial cell polarity or implantation. Expression of ROR2 by uterine NK cells may suggest WNT signaling regulates uterine NK cell functions such angiogenesis and regulation of trophoblast migration. In summary, our results show that ROR2 expression by maternal uterine cells is influenced by pregnancy.
Placenta 02/2010; 31(4):327-33. · 3.69 Impact Factor
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ABSTRACT: Human decidual stromal cells (DSC) have been shown to be involved in different immune functions that may be relevant for the relationship between the mother and fetus and hence for successful pregnancy. The expression of death ligands by fetal trophoblast and maternal decidual cells has been proposed as a mechanism for the establishment of materno-fetal immunotolerance. This study intended to elucidate the interrelations between DSC and lymphocytes. We analyzed the expression and function of death receptors and ligands in DSC maintained in culture. These DSC lines expressed CD95 and TNF-related apoptosis-inducing ligand receptor-2 (TRAIL-R2), although they were resistant to death receptor-mediated apoptosis. Regarding the expression of CD95L and TRAIL, it was variable among DSC lines although none of them induced apoptosis in death ligand-sensitive Jurkat T cells. Interestingly, most of the DSC lines, as well as fresh DSC, reduced apoptosis in Jurkat cells induced by anti-CD95 antibody and recombinant TRAIL. The protective effect of DSC was observed when they were co-cultured with Jurkat cells in Transwell plates, indicating that DSC may produce soluble factors of importance for lymphocyte survival. Moreover, the viability of peripheral blood lymphocytes and decidual lymphocytes was improved when co-cultured with DSC. Our results suggest that DSC, far from inducing apoptosis, may be relevant in the regulation of lymphocyte survival at the materno-fetal interface.
Placenta 07/2009; 30(8):677-85. · 3.69 Impact Factor
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Cell Death and Differentiation 10/2002; 9(9):1026-9. · 8.85 Impact Factor
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ABSTRACT: Bc1-2 protein is a potent anti-apoptotic protein that inhibits a mitochondria-operated pathway of apoptosis in many cells. DNA damaging agents and death receptor ligands can activate this mitochondrial apoptotic mechanism. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been suggested to escape from the inhibitory action of Bc1-2 protein. We show that in human breast tumor MCF-7 cells, TRAIL induced a mitochondrial pathway of apoptosis that involved cytochrome c release from mitochondria and activation of caspase 9. The DNA damaging drug doxorubicin also activated this mitochondria-regulated mechanism of apoptosis, which was inhibited in Bc1-2-overexpressing cells. We also demonstrate that in MCF-7 cells Bc1-2 might confer resistance to TRAIL-induced apoptosis, depending on the expression levels of the anti-apoptotic protein. These results indicate that enhanced expression of Bc1-2 in tumor cells can render these cells less sensitive not only to chemotherapeutic drugs but also to TRAIL.
Oncogene 11/2001; 20(48):7128-33. · 6.37 Impact Factor
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ABSTRACT: The role of interferon (IFN)-gamma as a sensitizing agent in apoptosis induced by ligation of death receptors has been evaluated in human myeloid leukemia cells. Incubation of U937 cells with IFN-gamma sensitized these cells to apoptosis induced by tumor necrosis factor-alpha, agonistic CD95 antibody, and tumor necrosis factor-related apoptosis-inducing ligand. Other human myeloid leukemic cells were also sensitized by IFN-gamma to death receptor-mediated apoptosis. Treatment of U937 cells with IFN-gamma up-regulated the expression of caspase-8 and potently synergized with death receptor ligation in the processing of caspase-8 and BID cleavage. Concomitantly, a marked down-regulation of BCL-2 protein was also observed in cells incubated with IFN-gamma. Furthermore, the caspase-dependent generation of a 23-kDa fragment of BCL-2 protein, the release of cytochrome c from mitochondria and the activation of caspase-9 were also enhanced upon death receptor ligation in IFN-gamma-treated cells. Ectopically expressed Bcl-2 protein inhibited IFN-gamma-induced sensitization to apoptosis. In summary, these results indicate that IFN-gamma sensitizes human myeloid leukemic cells to a death receptor-induced, mitochondria-mediated pathway of apoptosis.
Journal of Biological Chemistry 06/2001; 276(21):17779-87. · 4.77 Impact Factor
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ABSTRACT: TRAIL causes apoptosis in numerous types of tumor cells. However, the mechanisms regulating TRAIL-induced apoptosis remain to be elucidated. We have investigated the role of PKC in regulating TRAIL-induced mitochondrial events and apoptosis in the Jurkat T cell line. We found a caspase-dependent decline in mitochondrial membrane potential and translocation of cytochrome c from mitochondria into the cytosol in response to TRAIL. Both these events were prevented by PKC activation. Moreover, PKC activation considerably reduced the activation of caspases, PARP cleavage and apoptosis when induced upon TRAIL treatment. MAPK activation was involved in the mechanism of PKC-mediated inhibition of TRAIL-induced cytochrome c release from mitochondria. Furthermore, inhibition of the MAPK pathway partially reversed the PKC-mediated inhibition of TRAIL-induced apoptosis. Besides, PKC activation may also inhibit the TRAIL-induced apoptosis through a MAPK-independent mechanism. Altogether, these results indicate a negative role of PKC in the regulation of apoptotic signals generated upon TRAIL receptor activation.
Cell Death and Differentiation 03/2001; 8(2):172-81. · 8.85 Impact Factor
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ABSTRACT: In this report, we have assessed the role of IFN-gamma as a sensitizing agent in apoptosis mediated by activation of death receptor CD95 in breast tumor cells. Treatment of the tumor cell lines MCF-7 and MDA-MB231 with IFN-gamma significantly facilitated apoptosis induced by CD95 receptor ligation at the plasma membrane, independently of p53 status. In contrast, IFN-gamma treatment did not enhance the apoptotic effect of the DNA-damaging drug, doxorubicin. Analysis of apoptosis regulators indicated that caspase-8 mRNA and protein levels were up-regulated in both of the cell lines after treatment with IFN-gamma. Furthermore, IFN-gamma sensitized MCF-7 and MDA-MB231 cells to CD95-mediated activation of caspase-8, induction of cytochrome c release from mitochondria, and processing of caspase-9. Release of cytochrome c, caspases activation, and apoptosis were prevented in MCF-7 cells overexpressing Bcl-2. Altogether these results indicate that IFN-gamma, maybe through the elevation of caspase-8 levels, sensitizes human breast tumor cells to a death receptor-mediated, mitochondria-operated pathway of apoptosis.
Cancer Research 11/2000; 60(20):5673-80. · 7.86 Impact Factor
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ABSTRACT: We have recently reported that activation of protein kinase C (PKC) plays a negative role in CD95-mediated apoptosis in human T cell lines. Here we present data indicating that although the PKC-induced mitogen-activated protein kinase pathway could be partially implicated in the abrogation of CD95-mediated apoptosis by phorbol esters in Jurkat T cells, the major inhibitory effect is exerted through a PKC-dependent, mitogen-activated protein kinase-independent signaling pathway. Furthermore, we demonstrate that activation of PKC diminishes CD95 receptor aggregation elicited by agonistic CD95 Abs. On the other hand, it has been reported that UV radiation-induced apoptosis is mediated at least in part by the induction of CD95 oligomerization at the cell surface. Here we show that activation of PKC also inhibits UVB light-induced CD95 aggregation and apoptosis in Jurkat T cells. These results reveal a novel mechanism by which T cells may restrain their sensitivity to CD95-induced cell death through PKC-mediated regulation of CD95 receptor oligomerization at the cell membrane.
The Journal of Immunology 12/1999; 163(9):4737-46. · 5.79 Impact Factor
