Rottlerin inhibits human T cell responses

in Biochemical Pharmacology (2007), 73(4), 515-525

Rottlerin is a pharmacological inhibitor of protein kinase C (PKC) theta, a novel PKC selectively expressed in T lymphocytes. PKC theta is known to regulate T cell receptor (TCR)/CD28 signalling pathways ... [more ▼]

Rottlerin is a pharmacological inhibitor of protein kinase C (PKC) theta, a novel PKC selectively expressed in T lymphocytes. PKC theta is known to regulate T cell receptor (TCR)/CD28 signalling pathways in T lymphocytes, but the impact of PKC theta inhibition on human T cell responses remains undefined. In this work, we describe the effects of rottlerin on the responses of CD4+ and CD8+ human T lymphocytes upon polyclonal activation. We observed a dose-dependent inhibition of CD4+ and CD8+ T cell proliferation in response to anti-CD3/antiCD28 antibodies stimulation in the presence of rottlerin. This inhibition was associated with impaired CD25 expression and decreased interleukin (IL)-2 production in activated T cells. In contrast, rottlerin did not alter IL-2-induced T cell proliferation. Furthermore, we demonstrated that rottlerin blocked interferon (IFN) gamma, IL-10 and IL-13 mRNA expression in TCR/CD28 activated CD4+ T cells. These findings place rottlerin as a potent immunosuppressive agent for the development of novel therapies in T cell mediated immune disorders. (c) 2006 Elsevier Inc. All rights reserved. [less ▲]

Biomarker discovery for inflammatory bowel disease, using proteomic serum profiling

in Biochemical Pharmacology (2007), 73(9), 1422-1433

Crohn's disease and ulcerative colitis known as inflammatory bowel diseases (IBD) are chronic immuno-inflammatory pathologies of the gastrointestinal tract. These diseases are multifactorial, polygenic ... [more ▼]

Crohn's disease and ulcerative colitis known as inflammatory bowel diseases (IBD) are chronic immuno-inflammatory pathologies of the gastrointestinal tract. These diseases are multifactorial, polygenic and of unknown etiology. Clinical presentation is non-specific and diagnosis is based on clinical, endoscopic, radiological and histological criteria. Novel markers are needed to improve early diagnosis and classification of these pathologies. We performed a study with 120 serum samples collected from patients classified in 4 groups (30 Crohn, 30 ulcerative colitis, 30 inflammatory controls and 30 healthy controls) according to accredited criteria. We compared protein sera profiles obtained with a Surface Enhanced Laser Desorption Ionization-Time of Flight-Mass Spectrometer (SELDI-TOF-MS). Data analysis with univariate process and a multivariate statistical method based on multiple decision trees algorithms allowed us to select some potential biomarkers. Four of them were identified by mass spectrometry and antibody based methods. Multivariate analysis generated models that could classify samples with good sensitivity and specificity (minimum 80%) discriminating groups of patients. This analysis was used as a tool to classify peaks according to differences in level on spectra through the four categories of patients. Four biomarkers showing important diagnostic value were purified, identified (PF4, MRP8, FIBA and Hpalpha2) and two of these: PF4 and Hpalpha2 were detected in sera by classical methods. SELDI-TOF-MS technology and use of the multiple decision trees method led to protein biomarker patterns analysis and allowed the selection of potential individual biomarkers. Their downstream identification may reveal to be helpful for IBD classification and etiology understanding. [less ▲]

Can NF-kappa B be a target for novel and efficient anti-cancer agents?

in Biochemical Pharmacology (2006), 72(9), 1054-1068

Since the discovery of the NF-kappa B transcription factor in 1986 and the cloning of the genes coding for NF-kappa B and I kappa B proteins, many studies demonstrated that this transcription factor can ... [more ▼]

Since the discovery of the NF-kappa B transcription factor in 1986 and the cloning of the genes coding for NF-kappa B and I kappa B proteins, many studies demonstrated that this transcription factor can, in most cases, protect transformed cells from apoptosis and therefore participate in the onset or progression of many human cancers. Molecular studies demonstrated that ancient widely used drugs, known for their chemopreventive or therapeutic activities against human cancers, inhibit NF-kappa B, usually among other biological effects. It is therefore considered that the anti-cancer activities of NSAIDs (non-steroidal anti-inflammatory drugs) or glucocorticoids are probably partially related to the inhibition of NF-kappa B and new clinical trials are being initiated with old compounds such as sulfasalazine. In parallel, many companies have developed novel agents acting on the NF-kappa B pathway: some of these agents are supposed to be NF-kappa B specific (i.e. IKK inhibitors) while others have wide-range biological activities (i.e. proteasome inhibitors). Today, the most significant clinical data have been obtained with bortezomib, a proteasome inhibitor, for the treatment of multiple myeloma. This review discusses the preclinical and clinical data obtained with these various drugs and their putative future developments. (c) 2006 Elsevier Inc. All rights reserved. [less ▲]

Deregulated NF-kappa B activity in haematological malignancies

in Biochemical Pharmacology (2006), 72(9), 1069-1080

The NF-kappa B family of transcription factors plays key roles in the control of cell proliferation and apoptosis. Constitutive NF-kappa B activation is a common feature for most haematological ... [more ▼]

The NF-kappa B family of transcription factors plays key roles in the control of cell proliferation and apoptosis. Constitutive NF-kappa B activation is a common feature for most haematological malignancies and is therefore believed to be a crucial event for enhanced proliferation and survival of these malignant cells. In this review, we will describe the molecular mechanisms underlying NF-kappa B deregulation in haematological malignancies and will highlight what is still unclear in this field, 20 years after the discovery of this transcription factor. (c) 2006 Elsevier Inc. All rights reserved. [less ▲]

20 years of NF-kappa B

in Biochemical Pharmacology (2006), 72(9), 1051-1053

We are celebrating this year 20 years of research dedicated to the transcription factor NF-kB. From 1986, the year of its initial identification as a DNA-binding activity for the enhancer of the ... [more ▼]

We are celebrating this year 20 years of research dedicated to the transcription factor NF-kB. From 1986, the year of its initial identification as a DNA-binding activity for the enhancer of the immunoglobulin k light-chain in activated B cells by David Baltimore and colleagues [1] to 2006, almost 20000 papers related to this transcription factor were published, which means three reports per day. This amazing amount of data generated over the years and throughout the world reflects the critical roles played by NF-kB in biology. It is indeed increasingly difficult to find circumstances where NF-kB is not involved at one point. One reason is due to the amazing amount of signals that can activate NF-kB. They include bacterial, viral and fungal products but also inflammatory cytokines, oxidative stress and therapeutically used drugs (as reviewed by Y. Habraken and J. Piette in this issue) and are listed in Tom Gilmore’s website (www.nf-kb.org) (Boston University). Another reason is due to the functional kB sites found in about one hundred genes [2]. These numerous NF-kB target genes play critical roles in cell survival and proliferation, as well as in innate and adaptive immunity, which reflects the essential role of this transcription factor in physiology and diseases. [less ▲]

Can NF-kappaB be a target for novel and efficient anti-cancer agents?

in Biochemical Pharmacology (2006), 72(9), 1054-68

Since the discovery of the NF-kappaB transcription factor in 1986 and the cloning of the genes coding for NF-kappaB and IkappaB proteins, many studies demonstrated that this transcription factor can, in ... [more ▼]

Since the discovery of the NF-kappaB transcription factor in 1986 and the cloning of the genes coding for NF-kappaB and IkappaB proteins, many studies demonstrated that this transcription factor can, in most cases, protect transformed cells from apoptosis and therefore participate in the onset or progression of many human cancers. Molecular studies demonstrated that ancient widely used drugs, known for their chemopreventive or therapeutic activities against human cancers, inhibit NF-kappaB, usually among other biological effects. It is therefore considered that the anti-cancer activities of NSAIDs (non-steroidal anti-inflammatory drugs) or glucocorticoids are probably partially related to the inhibition of NF-kappaB and new clinical trials are being initiated with old compounds such as sulfasalazine. In parallel, many companies have developed novel agents acting on the NF-kappaB pathway: some of these agents are supposed to be NF-kappaB specific (i.e. IKK inhibitors) while others have wide-range biological activities (i.e. proteasome inhibitors). Today, the most significant clinical data have been obtained with bortezomib, a proteasome inhibitor, for the treatment of multiple myeloma. This review discusses the preclinical and clinical data obtained with these various drugs and their putative future developments. [less ▲]

Sodium nitroprusside-induced osteoblast apoptosis is mediated by long chain ceramide and is decreased by raloxifene.

in Biochemical Pharmacology (2005), 69(6), 891-901

Release of high levels of nitric oxide (NO) is associated with osteoblastic cell death. The mechanisms of NO-induced cytotoxicity are not well documented and it is presently not known if estrogenic ... [more ▼]

Release of high levels of nitric oxide (NO) is associated with osteoblastic cell death. The mechanisms of NO-induced cytotoxicity are not well documented and it is presently not known if estrogenic compounds prevent this effect. We studied the role of ceramides in cell death induced by the NO donor sodium nitroprusside (SNP) and we tested the possibility that 17beta-estradiol, the anti-estrogen ICI 182.780 and two selective estrogen receptor modulators raloxifene and tamoxifen modify osteoblastic cell apoptosis. SNP dose-dependently decreased MC3T3-E1 osteoblast viability, increased NO production in the culture media and enhanced the release of intracellular ceramides C22 and C24. Cell death induced by SNP was partially inhibited when MC3T3-E1 cells were pretreated with raloxifene and tamoxifen but was not modified when the cells were pretreated with 17beta-estradiol or ICI 182.780. Cell death induced by SNP resulted from apoptosis as demonstrated by Annexin-V and propidium iodide labeling and a reduction of SNP-induced MC3T3-E1 apoptosis was confirmed in the presence of raloxifene and tamoxifen. SNP induction of C22 and C24 production was inhibited by a pretreatment with raloxifene but not with 17beta-estradiol. Moreover, the synthetic ceramide C24 (0.75 and 1microM) decreased MC3T3-E1 cell viability and osteoblast cell death induced by C24 was partially decreased by raloxifene and to a lesser extent by 17beta-estradiol. These data demonstrate that SNP-induced cell death is mediated by the long chain ceramides C22 and C24 and that raloxifene protected osteoblast from apoptosis induced by SNP, an effect that might be relevant to its pharmacological properties on bone remodeling. [less ▲]

Prostaglandin E2 induces the expression of functional inhibitory CD94/NKG2A receptors in human CD8+ T lymphocytes by a cAMP-dependent protein kinase A type I pathway.

in Biochemical Pharmacology (2005), 70(5), 714-24

The CD94/NKG2A heterodimer is a natural killer receptor (NKR), which inhibits cell-mediated cytotoxicity upon interaction with MHC class I gene products. It is expressed by NK cells and by a small ... [more ▼]

The CD94/NKG2A heterodimer is a natural killer receptor (NKR), which inhibits cell-mediated cytotoxicity upon interaction with MHC class I gene products. It is expressed by NK cells and by a small fraction of activated T cells, predominantly of CD8+ phenotype. Abnormal upregulation of the CD94/NKG2A inhibitory NKR on cytotoxic T cells (CTLs) could be responsible for a failure of immunosurveillance in cancer or HIV infection. In an attempt to identify the mechanisms leading to inhibitory NKR upregulation on T cells, we analyzed the expression of the CD94/NKG2A heterodimer on human CTLs activated with anti-CD3 mAb in the presence of PGE2 or with 8-CPT-cAMP, an analogue of cyclic AMP. As previously described, anti-CD3 mAb-mediated activation induced the expression of CD94/NKG2A on a small fraction of CD8+ T cells. Interestingly, when low concentrations of PGE2 or 8-CPT-cAMP were present during the culture, the proportion of CD8+ T cells expressing CD94/NKG2A was two- to five-fold higher. This upregulation was partially prevented by PKA inhibitors, such as KT5720 and Rp-8-Br-cAMP (type I selective). We also report that cAMP induces upregulation of NKG2A at the mRNA level. We further demonstrated that cross-linking of CD94 on CD8+ T cells expressing the CD94/NKG2A heterodimer inhibits their cytotoxic activity in a bispecific antibody redirected lysis assay. Our findings clearly demonstrate that the PGE2/cAMP/PKA type I axis is involved in the expression of CD94/NKG2A receptor on human CD8+ T lymphocytes. [less ▲]

Mechanisms involved in exogenous C2- and C6-ceramide-induced cancer cell toxicity

in Biochemical Pharmacology (2003), 65(10), 1633-1642

Ceramides are important intracellular second messengers that play a role in the regulation of cell growth, differentiation, and programmed cell death. To determine whether ceramides can mediate the ... [more ▼]

Ceramides are important intracellular second messengers that play a role in the regulation of cell growth, differentiation, and programmed cell death. To determine whether ceramides can mediate the apoptosis of HCT116 and OVCAR-3 cancer cells, exogenous C2-, C6-, and C16-ceramides were used to mimic the endogenous lipid increase that follows a large variety of stresses. C2- and C6-ceramides (cell-permeable ceramide analogs), but not C16-ceramide, induced nuclear factor-kappaB (NF-kappaB) DNA-binding, caspase-3 activation, poly(ADP-ribose) polymerase degradation, and mitochondrial cytochrome c release, indicating that apoptosis occurs through the caspase cascade and the mitochondrial pathway. No difference in survival was observed between control cells and cells expressing mutated IkappaBalpha and treated with the permeable ceramides. This suggests that, at least in these cell lines, stable NF-kappaB inhibition did not modify the ceramide-induced cytotoxicity pathway. C6-ceramide also induced a double block in G1 and G2, thus emptying the S phase. [less ▲]

Mechanisms involved in exogenous C2- and C6-ceramide-induced cancer cell toxicity.

in Biochemical Pharmacology (2003), 65(10), 1633-42

Ceramides are important intracellular second messengers that play a role in the regulation of cell growth, differentiation, and programmed cell death. To determine whether ceramides can mediate the ... [more ▼]

Ceramides are important intracellular second messengers that play a role in the regulation of cell growth, differentiation, and programmed cell death. To determine whether ceramides can mediate the apoptosis of HCT116 and OVCAR-3 cancer cells, exogenous C2-, C6-, and C16-ceramides were used to mimic the endogenous lipid increase that follows a large variety of stresses. C2- and C6-ceramides (cell-permeable ceramide analogs), but not C16-ceramide, induced nuclear factor-kappaB (NF-kappaB) DNA-binding, caspase-3 activation, poly(ADP-ribose) polymerase degradation, and mitochondrial cytochrome c release, indicating that apoptosis occurs through the caspase cascade and the mitochondrial pathway. No difference in survival was observed between control cells and cells expressing mutated IkappaBalpha and treated with the permeable ceramides. This suggests that, at least in these cell lines, stable NF-kappaB inhibition did not modify the ceramide-induced cytotoxicity pathway. C6-ceramide also induced a double block in G1 and G2, thus emptying the S phase. [less ▲]