Therapeutic efficacy of CEP-33779, a novel selective JAK2 inhibitor, in a mouse model of colitis-induced colorectal cancer.

Constitutively activated STAT3 and STAT5 are expressed in a wide variety of human malignancies including solid and hematopoietic cancers and often correlate with a poor prognosis and resistance to multiple therapies. Given the well established role of STAT3 in tumorigenesis, inhibition of Janus-activated kinase 2 (JAK2) activity might represent an attractive therapeutic approach. Using a mouse model of colitis-induced colorectal cancer, we show that a novel, orally active, selective JAK2 inhibitor, CEP-33779, induced regression of established colorectal tumors, reduced angiogenesis, and reduced proliferation of tumor cells. Histopathologic analysis confirmed reduced incidence of histologic-grade neoplasia by CEP-33779. Tumor regression correlated with inhibition of STAT3 and NF-κB (RelA/p65) activation in a CEP-33779 dose-dependent manner. In addition, the expression of proinflammatory, tumor-promoting cytokines interleukin (IL)-6 and IL-1ß was strongly reduced upon JAK2 inhibition. The ability of CEP-33779 to suppress growth of colorectal tumors by inhibiting the IL-6/JAK2/STAT3 signaling suggests a potential therapeutic utility of JAK2 inhibitors in multiple tumors types, particularly those with a strong inflammatory component.

Optimization of a novel kinase inhibitor scaffold for the dual inhibition of JAK2 and FAK kinases.

The elaboration of a novel scaffold for the inhibition of JAK2 and FAK kinases was targeted in order to provide a dual inhibitor that could target divergent pathways for tumor cell progression.

The phosphatidylinositol 3-kinase inhibitor LY 294002 inhibits GlyT1-mediated glycine uptake.

The actions of neurotransmitter glycine are regulated by the Na+/Cl(-) dependent high-affinity glycine transporters, GlyT1 and GlyT2. These two members of the SLC6 transport family have been cloned and extensively characterized, however relatively little is known regarding their modulation. In the present study, glycine uptake in primary cultures of rat embryonic cortex has been characterized and the effects of the phosphatidylinositol 3 (PI3) kinase inhibitors LY 294002 and wortmannin on GlyT1- and GlyT2-mediated glycine uptake were investigated. GlyT1 inhibitors ALX 5407 and sarcosine reduced total glycine uptake to 80% whereas the specific GlyT2 inhibitor Org 25543 had no effect. In the presence of alanine, glycine uptake was completely blocked by the GlyT1 inhibitors ALX 5407 and sarcosine, suggesting that the high-affinity glycine uptake occurs predominantly via GlyT1. Kinetic analysis of GlyT1 revealed the Km value of 27+/-1.5 microM and Vmax value of 157+/-14 pmol/mg/min. LY 294002, a PI3 kinase inhibitor, blocked the GlyT1-mediated glycine uptake with an IC50 value of 81+/-2 microM, whereas another inhibitor wortmannin did not show any effect. In human placental choriocarcinoma (JAR) cells, which have been previously shown to predominantly express GlyT1a, LY 294002 showed a similar potency with an IC50 value of 86+/-3 microM. Immunoblots demonstrated that LY 294002 and wortmannin inhibited PI3 kinase-dependent Akt phosphorylation in the primary cultures with IC50 values of 10+/-4 microM and 7+/-1 nM, respectively. These results suggest that the commonly used PI3 kinase blocker LY 294002 may modulate GlyT1 function independent of PI3 kinase inhibition. Kinetic analysis in the presence of LY 294002 demonstrated significant decreases of both Km and Vmax values, suggesting a mechanism of uncompetitive inhibition on GlyT1-mediated glycine uptake. In addition, glycine release was blocked by LY 294002. These results raised a possibility that LY 294002 might interact with GlyT1.

Comparative analysis of cortical gene expression in mouse models of Alzheimer's disease.

Three mouse models of Alzheimer's disease (AD) were used to assess changes in gene expression potentially critical to amyloid beta-peptide (Abeta)-induced neuronal dysfunction. One mouse model harbored homozygous familial AD (FAD) knock-in mutations in both, amyloid precursor protein (APP) and presenilin 1 (PS-1) genes (APP(NLh/NLh)/PS-1(P264L/P264L)), the other two models harbored APP over-expression of FAD mutations (Tg2576) with the PS-1 knock-in mutation at either one or two alleles. These mouse models of AD had varying levels of Abeta40 and Abeta42 and different latencies and rates of Abeta deposition in brain. To assess changes in gene expression associated with Abeta accumulation, the Affymetrix murine genome array U74A was used to survey gene expression in the cortex of these three models both prior to and following Abeta deposition. Altered genes were identified by comparing the AD models with age-matched control littermates. Thirty-four gene changes were identified in common among the three models in mice with Abeta deposition. Among the up-regulated genes, three major classes were identified that encoded for proteins involved in immune responses, carbohydrate metabolism, and proteolysis. Down-regulated genes of note included pituitary adenylate cyclase-activating peptide (PACAP), brain-derived neurotrophic factor (BDNF), and insulin-like growth factor I receptor (IGF-IR). In young mice without detectable Abeta deposition, there were no regulated genes common among the three models, although 40 genes were similarly altered between the two Tg2576 models with the PS-1 FAD knock-in. Finally, changes in gene expression among the three mouse models of AD were compared with those reported in human AD samples. Sixty-nine up-regulated and 147 down-regulated genes were found in common with human AD brain. These comparisons across different genetic mouse models of AD and human AD brain provide greater support for the involvement of identified gene expression changes in the neuronal dysfunction and cognitive deficits accompanying amyloid deposition in mammalian brain.

Protein tyrosine phosphatases are up-regulated and participate in cell death induced by polyglutamine expansion.

Polyglutamine expansion is the cause of several neurodegenerative diseases. An in vitro model of polyglutamine-induced neuronal cell death was developed using truncated mutant huntingtin (Htt) and PC12 cells. Cell death was specifically observed in cells expressing a truncated mutant huntingtin-green fluorescence protein (GFP) fusion protein with 118 glutamine repeats (Gln(118)), as demonstrated by the release of lactate dehydrogenase (LDH). To gain further insights into the mechanisms of polyglutamine expansion-induced cell death, the Affymetrix rat genome array U34A was used to investigate gene expression changes associated with polyglutamine-mediated protein aggregation and cell death. Among the up-regulated genes, the increase of four protein tyrosine phosphatases (PTPs) was further confirmed by real-time quantitative reverse transcription PCR. Protein expression of mitogen activated protein (MAP) kinase phosphatase 1 (MKP1) was also increased as demonstrated by Western blot. Furthermore, phosphorylation of MAP kinase extracellular signal-regulated kinase 1/2 (ERK1/2) was substantially reduced in association with protein aggregation, and two general PTP inhibitors, sodium orthovanadate and bpV(pic), dramatically rescued the cells from polyglutamine-induced cell death. These results suggest that one or more of the PTPs are involved in the polyglutamine-induced cell death.

Mixed lineage kinase activity of indolocarbazole analogues.

The MLK1-3 activity for a series of analogues of the indolocarbazole K-252a is reported. Addition of 3,9-bis-alkylthiomethyl groups to K-252a results in potent and selective MLK inhibitors. The in vitro and in vivo survival promoting activity of bis-isopropylthiomethyl-K-252a (16, CEP-11004/KT-8138) is reported.