Randomised clinical trial: vercirnon, an oral CCR9 antagonist, vs. placebo as induction therapy in active Crohn's disease

BACKGROUND

Many patients with active Crohn's disease do not adequately respond to therapies, highlighting the need for new treatments.

AIMS

To conduct a randomised, double-blind, placebo-controlled phase 3 study to assess the efficacy and safety of vercirnon, an oral inhibitor of CC chemokine receptor-9, for the treatment of patients with moderately-to-severely active Crohn's disease.

METHODS

Patients with a Crohn's Disease Activity Index (CDAI) of 220-450, plus evidence of active disease (endoscopically confirmed or elevation of both C-reactive protein and faecal calprotectin), who had failed corticosteroid or immunosuppressant therapy were enrolled. Patients were equally randomised to receive placebo, vercirnon 500 mg once daily or vercirnon 500 mg twice daily. The primary endpoint was clinical response, defined as a 100-point decrease in CDAI from baseline to week 12.

RESULTS

Six hundred and eight patients were randomised. Patient characteristics and baseline demographics were similar among the groups. The proportions of patients achieving a clinical response were 25.1%, 27.6% and 27.2% for placebo, once daily and twice daily respectively; treatment differences were not significant (2.5%; 95% confidence interval, CI -6.1% to 11.0%, P = 0.546 for once daily vs. placebo, and 2.1%; 95% CI -6.5% to 10.7%, P = 0.648 for twice daily vs. placebo). Adverse events were reported in 69.8%, 73.3% and 78.1% with serious adverse events in 8.9%, 5.9%, and 6.0% of patients in the placebo, once-daily and twice-daily groups, respectively.

CONCLUSIONS

We did not demonstrate efficacy of vercirnon as an induction therapy in patients with moderately-to-severely active Crohn's disease; its effect in maintenance therapy was not addressed.

c-Jun N-terminal kinase specifically phosphorylates p66ShcA at serine 36 in response to ultraviolet irradiation

Mice lacking expression of the p66 isoform of the ShcA adaptor protein (p66(ShcA)) are less susceptible to oxidative stress and have an extended life span. Specifically, phosphorylation of p66(ShcA) at serine 36 is critical for the cell death response elicited by oxidative damage. We sought to identify the kinase(s) responsible for this phosphorylation. Utilizing the SH-SY5Y human neuroblastoma cell model, it is demonstrated that p66(ShcA) is phosphorylated on serine/threonine residues in response to UV irradiation. Both c-Jun N-terminal kinases (JNKs) and p38 mitogen-activated protein kinases are activated by UV irradiation, and we show that both are capable of phosphorylating serine 36 of p66(ShcA) in vitro. However, treatment of cells with a multiple lineage kinase inhibitor, CEP-1347, that blocks UV-induced JNK activation, but not p38, phosphatidylinositol 3-kinase, or MEK1 inhibitors, prevented p66(ShcA) phosphorylation in SH-SY5Y cells. Consistent with this finding, transfected activated JNK1, but not the kinase-dead JNK1, leads to phosphorylation of serine 36 of p66(ShcA) in Chinese hamster ovary cells. In conclusion, JNKs are the kinases that phosphorylate serine 36 of p66(ShcA) in response to UV irradiation in SH-SY5Y cells, and blocking p66(ShcA) phosphorylation by intervening in the JNK pathway may prevent cellular damage due to light-induced oxidative stress.

Cep-1347 (KT7515), a semisynthetic inhibitor of the mixed lineage kinase family

CEP-1347 (KT7515) promotes neuronal survival at dosages that inhibit activation of the c-Jun amino-terminal kinases (JNKs) in primary embryonic cultures and differentiated PC12 cells after trophic withdrawal and in mice treated with 1-methyl-4-phenyl tetrahydropyridine. In an effort to identify molecular target(s) of CEP-1347 in the JNK cascade, JNK1 and known upstream regulators of JNK1 were co-expressed in Cos-7 cells to determine whether CEP-1347 could modulate JNK1 activation. CEP-1347 blocked JNK1 activation induced by members of the mixed lineage kinase (MLK) family (MLK3, MLK2, MLK1, dual leucine zipper kinase, and leucine zipper kinase). The response was selective because CEP-1347 did not inhibit JNK1 activation in cells induced by kinases independent of the MLK cascade. CEP-1347 inhibition of recombinant MLK members in vitro was competitive with ATP, resulting in IC(50) values ranging from 23 to 51 nm, comparable to inhibitory potencies observed in intact cells. In addition, overexpression of MLK3 led to death in Chinese hamster ovary cells, and CEP-1347 blocked this death at doses comparable to those that inhibited MLK3 kinase activity. These results identify MLKs as targets of CEP-1347 in the JNK signaling cascade and demonstrate that CEP-1347 can block MLK-induced cell death.

The MLK family mediates c-Jun N-terminal kinase activation in neuronal apoptosis

Neuronal apoptotic death induced by nerve growth factor (NGF) deprivation is reported to be in part mediated through a pathway that includes Rac1 and Cdc42, mitogen-activated protein kinase kinases 4 and 7 (MKK4 and -7), c-Jun N-terminal kinases (JNKs), and c-Jun. However, additional components of the pathway remain to be defined. We show here that members of the mixed-lineage kinase (MLK) family (including MLK1, MLK2, MLK3, and dual leucine zipper kinase [DLK]) are expressed in neuronal cells and are likely to act between Rac1/Cdc42 and MKK4 and -7 in death signaling. Overexpression of MLKs effectively induces apoptotic death of cultured neuronal PC12 cells and sympathetic neurons, while expression of dominant-negative forms of MLKs suppresses death evoked by NGF deprivation or expression of activated forms of Rac1 and Cdc42. CEP-1347 (KT7515), which blocks neuronal death caused by NGF deprivation and a variety of additional apoptotic stimuli and which selectively inhibits the activities of MLKs, effectively protects neuronal PC12 cells from death induced by overexpression of MLK family members. In addition, NGF deprivation or UV irradiation leads to an increase in both level and phosphorylation of endogenous DLK. These observations support a role for MLKs in the neuronal death mechanism. With respect to ordering the death pathway, dominant-negative forms of MKK4 and -7 and c-Jun are protective against death induced by MLK overexpression, placing MLKs upstream of these kinases. Additional findings place the MLKs upstream of mitochondrial cytochrome c release and caspase activation.

beta-Amyloid-induced neuronal apoptosis requires c-Jun N-terminal kinase activation

beta-Amyloid (A beta) has been strongly implicated in the pathophysiology of Alzheimer's disease (AD), but the means by which the aggregated form of this molecule induces neuronal death have not been fully defined. Here, we examine the role of the c-Jun N-terminal kinases (JNKs) and of their substrate, c-Jun, in the death of cultured neuronal PC12 cells and sympathetic neurons evoked by exposure to aggregated A beta. The activities of JNK family members increased in neuronal PC12 cells within 2 h of A beta treatment and reached 3--4-fold elevation by 6 h. To test the role of these changes in death caused by A beta, we examined the effects of CEP-1347 (KT7515), an indolocarbazole that selectively blocks JNK activation. Inclusion of CEP-1347 (100--300 nM) in the culture medium effectively blocked the increases in cellular JNK activity caused by A beta and, at similar concentrations, protected both PC12 cells and sympathetic neurons from A beta-evoked-death. Effective protection required addition of CEP-1347 within 2 h of A beta treatment, indicating that the JNK pathway acts relatively proximally and as a trigger in the death mechanism. A dominant-negative c-Jun construct also conferred protection from A beta-evoked death, supporting a model in which JNK activation contributes to death via activation of c-Jun. Finally, CEP-1347 blocked A beta-stimulated activation of caspase-2 and -3, placing these downstream of JNK activation. These observations implicate the JNK pathway as a required element in death evoked by A beta and hence identify it as a potential therapeutic target in AD.

CEP-1347 (KT7515), an inhibitor of JNK activation, rescues sympathetic neurons and neuronally differentiated PC12 cells from death evoked by three distinct insults

The c-Jun N-terminal kinase signaling cascade appears to play a role in some cases of cell death, including neuronal apoptosis. CEP-1347 (KT7515), an indolocarbazole of the K252a family, blocks this stress signaling cascade and promotes survival. Here, we used CEP-1347 to probe whether neuronal death pathways activated by distinct insults also possess elements in common. Cultured rat sympathetic neurons and neuronally differentiated PC12 cells were induced to die by withdrawal of nerve growth factor, exposure to ultraviolet irradiation, or subjection to oxidative stress. In each case, death was prevented by 100-200 nM CEP-1347. Moreover, in each of these death paradigms, c-Jun N-terminal kinase 1 activity in neuronally differentiated PC12 cells was elevated by two- or threefold, and this increase was totally blocked by CEP-1347 at concentrations that promoted survival. In contrast, 200 nM CEP-1347 did not block death due to serum withdrawal from undifferentiated PC12 cells or to activation of Fas in Jurkat T cell cultures, even though in each case c-Jun N-terminal kinase 1 activation occurred and was inhibited by CEP-1347. These observations suggest that some but not all death pathways triggered by different insults can include a common mechanistic component, a likely candidate for which is activation of the c-Jun N-terminal kinase signaling cascade.

Motoneuron apoptosis is blocked by CEP-1347 (KT 7515), a novel inhibitor of the JNK signaling pathway

Neurons undergoing apoptosis can be rescued by trophic factors that simultaneously increase the activity of extracellular signal-regulated kinase (ERK) and decrease c-Jun N-terminal kinase (JNK) and p38. We identified a molecule, CEP-1347 (KT7515), that rescues motoneurons undergoing apoptosis and investigated its effect on ERK1 and JNK1 activity. Cultured rat embryonic motoneurons, in the absence of trophic factor, began to die 24-48 hr after plating. During the first 24 hr ERK1 activity was unchanged, whereas JNK1 activity increased fourfold. CEP-1347 completely rescued motoneurons for at least 72 hr with an EC50 of 20 +/- 2 nM. CEP-1347 did not alter ERK1 activity but rapidly inhibited JNK1 activation. The IC50 of CEP-1347 for JNK1 activation was the same as the EC50 for motoneuron survival. Inhibition of JNK1 activation by CEP-1347 was not selective to motoneurons. CEP-1347 also inhibited JNK1 activity in Cos7 cells under conditions of ultraviolet irradiation, osmotic shock, and inhibition of glycosylation. Inhibition by CEP-1347 of the JNK1 signaling pathway appeared to be selective, because CEP-1347 did not inhibit p38-regulated mitogen-activated protein kinase-activated protein kinase-2 (MAPKAP2) activity in Cos7 cells subjected to osmotic shock. The direct molecular target of CEP-1347 was not JNK1, because CEP-1347 did not inhibit JNK1 activity in Cos7 cells cotransfected with MEKK1 and JNK1 cDNA constructs. This is the first demonstration of a small organic molecule that promotes motoneuron survival and that simultaneously inhibits the JNK1 signaling cascade.

CEP-751 inhibits TRK receptor tyrosine kinase activity in vitro exhibits anti-tumor activity

The present report describes the in vitro and in vivo profile of CEP-751, a novel receptor tyrosine kinase inhibitor. CEP-751 at 100 nM inhibits the receptor tyrosine kinase activity of the neurotrophin receptors trkA, trkB and trkC. CEP-751 has no effect on activity of receptors for EGF, IGF-I, insulin or on erbB2; inhibition of receptors for PDGF and bFGF was observed but occurred with lesser potency than inhibition of trk. CEP-751 exhibited anti-tumor efficacy against tumors derived from NIH3T3 cells transfected with trkA. Inhibition of trk phosphorylation could also be measured in these tumors, suggesting that anti-tumor efficacy of CEP-751 is related to inhibition of trk receptor tyrosine kinase activity. CEP-751 was found to be without effect when administered to nude mice bearing SK-OV-3 tumors, which overexpress erbB2 receptors, providing further evidence that inhibition of tumor growth may be related to inhibition of trk receptor tyrosine kinase activity. Our data indicate that CEP-751 is a potent trk inhibitor which possesses anti-tumor activity.

A radioactive binding assay for inhibitors of trkA kinase

The high-affinity receptor for nerve growth factor (NGF), trkA, is a receptor-linked tyrosine kinase. The binding of NGF to trkA, depending on the context of its environment, can cause beneficial or deleterious responses in the target cells. For example, the activation of trkA in sympathetic and sensory neurons causes the subsequent survival and differentiation of these cells. On the other hand, the activation of trkA by NGF in other cells has been implicated in several pathologies including inflammation-induced hyperalgesia and several cancers. A radioactive binding assay to evaluate inhibitors of the kinase domain of trkA has been developed and validated. The assay monitors the specific binding of an inhibitor of trkA kinase activity, the indolocarbazole K-252a, to the trkA receptor. [3H]K-252a binds with high affinity to one site on the cytoplasmic kinase domain of the trkA receptor. Binding is saturable and reversible with a dissociation constant (Kd) of 1.5 nM. The binding assay has been used in competition binding experiments to determine the inhibition constants for other indolocarbazole compounds. The IC50 values for compounds obtained in the binding assay correlate very well with the IC50 values obtained in an enzyme-linked immunosorbent assay for trkA tyrosine kinase activity.

K-252b potentiation of neurotrophin-3 is trkA specific in cells lacking p75NTR

K-252b potentiates the neurotrophic effects of neurotrophin-3 (NT-3) in primary cultures of rat central cholinergic and peripheral sensory neurons and in a rat pheochromocytoma PC12 cell line. The ligand and receptor specificity, and role of the low-affinity neurotrophin receptor (p75NTR) in the potentiation response induced by K-252b, are unknown. To address the issues of ligand and receptor specificity of K-252b potentiation, we have examined neurotrophin-induced DNA synthesis ([3H]-thymidine incorporation) in NIH3T3 cells expressing trkA, trkB, or trkC. Neither NT-3 nor K-252b alone could stimulate mitogenic activity in the trkA-overexpressing clone. However, coaddition of K-252b (EC50 of approximately 2 nM) with 10-100 ng/ml NT-3 led to incorporation of [3H]thymidine in trkA expressing cells to a level induced by optimal concentrations of nerve growth factor (NGF). The K-252b- and NT-3-induced [3H]thymidine incorporation correlated with an increase in the tyrosine autophosphorylation of the trkA receptor as well as tyrosine phosphorylation of trk-associated phospholipase C-gamma 1 and SH2-containing proteins. K-252b did not potentiate submaximal doses of NGF, or maximal doses of brain-derived neurotrophic factor (BDNF) or neurotrophin-4/5 (NT-4/ 5) in trkA-expressing cells. Furthermore, K-252b did not potentiate DNA synthesis by submaximal doses of BDNF, NT-4/5, or NT-3 in trkB- or trkC-expressing NIH3T3 cells, suggesting that the potentiation profile for K-252b was specific for NT-3 in trkA-expressing cells. We found no expression of p75NTR in the trk-expressing NIH3T3 cells. This is the first demonstration that K-252b potentiates a trkA-mediated biological nonneuronal response by NT-3 that occurs independent of p75NTR and appears to be both ligand and receptor specific.

Membranes of human neuroblastoma SH-SY5Y cells contain specific binding sites for [3H]K-252A

K-252a and the structurally similar compound staurosporine promote neurotrophic responses in several cell lines (PC12, SH-SY5Y human neuroblastoma) and in cultures of primary neurons. The molecular mechanisms involved in the induction of these neurotrophic activities are unknown. It is demonstrated in this report that [3H]K-252a binds to SH-SY5Y membranes and that the binding is specific and saturable with a Kd of 2.7 nM and a Bmax of 100,000 sites per cell. The association of [3H]K-252a with its binding site is rapid and reversible, and the binding was inhibited by unlabeled K-252a and by staurosporine. Binding of [3H]K-252a was not inhibited by the potent protein kinase C (PKC) inhibitor GF109203X. Down regulation of PKC by treating SH-SY5Y cells with a phorbol ester did not cause a reduction in the specific binding of [3H]K-252a to membranes, suggesting that the binding is not to PKC. Treatment of the SH-SY5Y membranes with trypsin and by boiling destroyed all specific binding of [3H]K-252a. These results suggest that the [3H]K-252a binds to a specific protein site that is associated with membranes of SH-SY5Y cells.

K-252a induces tyrosine phosphorylation of the focal adhesion kinase and neurite outgrowth in human neuroblastoma SH-SY5Y cells

The protein kinase inhibitor K-252a has been shown to promote cholinergic activity in cultures of rat spinal cord and neuronal survival in chick dorsal root ganglion cultures. To determine the mechanism by which K-252a acts as a neurotrophic factor, we examined the effects of this molecule on a human neuroblastoma cell line, SH-SY5Y. K-252a induced neurite outgrowth in a dose-dependent manner. Coincident with neurite outgrowth was the early tyrosine phosphorylation of 125- and 140-kDa proteins. The phosphorylation events were independent of protein kinase C inhibition because down-regulation of protein kinase C by long-term treatment with phorbol ester did not prevent K252a-induced tyrosine phosphorylation. Similarly, the protein kinase C inhibitors H7, GF-109203X, and calphostin C did not induce the phosphorylation. We have identified one of the phosphosubstrates as the pp125 focal adhesion protein tyrosine kinase (Fak). Induction of phosphorylation coincided with increased Fak activity and appeared to be independent of ligand/integrin interaction. The induction of Fak phosphorylation by K-252a was also observed in LA-N-5 cells and primary cultures of rat embryonic striatal cells but not in PC12 cells. The protein kinase C-independent induction of tyrosine phosphorylation and the identification of Fak as a substrate of K-252a-induced tyrosine kinase activity suggest that this compound mediates neurotrophic effects through a novel signaling pathway.

Cloning and characterization of a thermolabile v-src gene for use in reversible transformation of mammalian cells

The use of temperature-sensitive (ts) src mutants for studies of cell transformation and differentiation has been limited by the availability of cloned ts-src genes that are inactivated at temperatures compatible with growth of mammalian cells. In this report, we describe the cloning and characterization of the tsLA90src gene, which displays tight thermal sensitivity at 39.5 degrees C. Nucleotide sequence comparison of tsLA90 and wild-type src genes from the Schmidt-Ruppin subgroup A and D strains of Rous sarcoma virus (RSV) revealed four amino acid differences in tsLA90src. Substitution of one of these residues (Lys-280) from tsLA90src with its wild-type homolog (Glu-280) caused a reversion to a wild-type src phenotype. The cloned tsLA90 gene, designated tsUP1, was introduced into avian and mammalian retroviral vectors. Chicken embryo fibroblasts and immortalized mouse 3T3 cells infected with these viral vectors displayed a temperature-dependent transformed phenotype as assessed by cell morphology, secretion of plasminogen activator, transcriptional activation of the primary response genes, Egr-1 and TIS 10, and stimulation of tyrosine phosphorylation. In addition, chicken myoblasts (infected with RSVtsUP1) showed a temperature-dependent differentiation into myotubes. Thus, this cloned src gene should be ideally suited for inducing reversible transformation and differentiation of mammalian cells in culture.

Translocation of diacylglycerol kinase from the cytosol to the membrane in phorbol ester-treated Swiss 3T3 fibroblasts

The tumor-promoting phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate, causes a rapid, partial redistribution of 1,2-diacylglycerol kinase from the cytosol to the particulate fraction of quiescent Swiss 3T3 fibroblasts. The inactive alpha form of the phorbol ester does not cause any change in diacylglycerol kinase localization, and depletion of protein kinase C by chronic administration of phorbol ester blocks the redistribution. Phorbol ester has no direct effect on membrane-bound diacylglycerol kinase in 3T3 cells. When phorbol ester is added to 3T3 membranes in the presence of ATP, Mg2+, and Ca2+, there is no activation of membrane-bound kinase, indicating that phorbol ester does not activate membrane-bound kinase through phosphorylation by protein kinase C. Stimulation of the cells with phorbol ester increases the total mass of diacylglycerol. In protein kinase C-depleted cells, addition of a cell-permeable synthetic diacylglycerol, dioctanoylglycerol, results in a partial redistribution of cytosolic diacylglycerol kinase to the membrane, also suggesting that the translocation of DAG kinase is regulated primarily by substrate concentration.

Phorbol ester-induced translocation of diacylglycerol kinase from the cytosol to the membrane in Swiss 3T3 fibroblasts

The tumor-promoting phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate, causes a rapid, partial redistribution of 1,2-sn-diacylglycerol kinase from the cytosol to the particulate fraction of quiescent, starved Swiss 3T3 fibroblasts. We utilized exogenous dioleoylglycerol as substrate for the kinase. The inactive alpha form of the phorbol ester does not cause any change in diacylglycerol kinase localization, and depletion of protein kinase C (Ca2+/phospholipid-dependent enzyme) by chronic administration of phorbol ester blocks the redistribution. Phorbol ester has no direct effect on Swiss 3T3 membrane-bound diacylglycerol kinase nor does it directly effect cytosolic diacylglycerol kinase. When phorbol ester is added to Swiss 3T3 membranes in the presence of ATP, magnesium, and calcium, there is no activation of membrane-bound kinase, indicating that phorbol ester does not activate membrane-bound kinase through phosphorylation by protein kinase C. Reconstitution studies show that the soluble rat brain diacylglycerol kinase binds to diacylglycerol-enriched membranes, produced by treatment of red cell ghosts with phospholipase C or calcium, suggesting that cytosolic diacylglycerol kinase may be capable of translocation to the membrane in response to elevated substrate concentration in the intact cell. Stimulation of the cells with phorbol ester increases the total mass of diacylglycerol. In protein kinase C-depleted cells, addition of a cell-permeable synthetic diacylglycerol, dioctanoylglycerol, results in a partial redistribution of cytosolic diacylglycerol kinase to the membrane, by 5 min, also suggesting that the translocation of diacylglycerol kinase activity is regulated primarily by substrate concentration.