Targeting Acute Myelogenous Leukemia Using Potent Human Dihydroorotate Dehydrogenase Inhibitors Based on the 2-Hydroxypyrazolo[1,5-]pyridine Scaffold: SAR of the Aryloxyaryl Moiety.

In recent years, human dihydroorotate dehydrogenase inhibitors have been associated with acute myelogenous leukemia as well as studied as potent host targeting antivirals. Starting from MEDS433 (IC 1.2 nM), we kept improving the structure-activity relationship of this class of compounds characterized by 2-hydroxypyrazolo[1,5-]pyridine scaffold.

AMPK activation attenuates HER3 upregulation and Neuregulin-Mediated rescue of cell proliferation in HER2-Overexpressing breast cancer cell lines exposed to lapatinib.

Lapatinib is a highly selective reversible inhibitor of the tyrosine kinase domains of HER2 and EGFR, approved for the treatment of advanced stage HER2-overexpressing breast cancers. Although targeted therapy with lapatinib provides initial clinical advantage, cancer cells' adaptive responses can overcome the inhibitory effects of lapatinib. HER3 upregulation and autocrine induction of HER3 ligand neuregulin-1 (NRG), have been implicated in the restoration of AKT and ERK1/2 activity and rescue of cell proliferation.

Targeting Acute Myelogenous Leukemia Using Potent Human Dihydroorotate Dehydrogenase Inhibitors Based on the 2-Hydroxypyrazolo[1,5-]pyridine Scaffold: SAR of the Biphenyl Moiety.

The connection with acute myelogenous leukemia (AML) of dihydroorotate dehydrogenase (DHODH), a key enzyme in pyrimidine biosynthesis, has attracted significant interest from pharma as a possible AML therapeutic target. We recently discovered compound , a potent DHODH inhibitor (IC = 1.2 nM), able to induce myeloid differentiation in AML cell lines (THP1) in the low nM range (EC = 32.

Targeting Myeloid Differentiation Using Potent 2-Hydroxypyrazolo[1,5- a]pyridine Scaffold-Based Human Dihydroorotate Dehydrogenase Inhibitors.

Human dihydroorotate dehydrogenase ( hDHODH) catalyzes the rate-limiting step in de novo pyrimidine biosynthesis, the conversion of dihydroorotate to orotate. hDHODH has recently been found to be associated with acute myelogenous leukemia, a disease for which the standard of intensive care has not changed over decades. This work presents a novel class of hDHODH inhibitors, which are based on an unusual carboxylic group bioisostere 2-hydroxypyrazolo[1,5- a]pyridine, that has been designed starting from brequinar, one of the most potent hDHODH inhibitors.

Design, synthesis, biological evaluation and X-ray structural studies of potent human dihydroorotate dehydrogenase inhibitors based on hydroxylated azole scaffolds.

A new generation of potent hDHODH inhibitors designed by a scaffold-hopping replacement of the quinolinecarboxylate moiety of brequinar, one of the most potent known hDHODH inhibitors, is presented here. Their general structure is characterized by a biphenyl moiety joined through an amide bridge with an acidic hydroxyazole scaffold (hydroxylated thiadiazole, pyrazole and triazole). Molecular modelling suggested that these structures should adopt a brequinar-like binding mode involving interactions with subsites 1, 2 and 4 of the hDHODH binding site.

Exposure of neuroblastoma cell lines to imatinib results in the upregulation of the CDK inhibitor p27(KIP1) as a consequence of c-Abl inhibition.

Imatinib mesylate is a tyrosine kinase inhibitor with selectivity for abelson tyrosine-protein kinase 1 (c-Abl), breakpoint cluster region (Bcr)-Abl fusion protein (Bcr-Abl), mast/stem cell growth factor receptor Kit (c-Kit), and platelet-derived growth factor receptor (PDGFR). Previous studies demonstrated that imatinib in the low micromolar range exerted antiproliferative effects on neuroblastoma cell lines. However, although neuroblastoma cells express c-Kit and PDGFR, the imatinib concentrations required to achieve significant growth inhibitory effects (≥ 10 μM) are substantially higher than those required for inhibition of ligand-induced phosphorylation of wild type c-Kit and PDGFR (≤ 1 μM), suggesting that additional mechanisms are responsible for the antitumor activity of imatinib on these cells.

Reduced cellular Ca(2+) availability enhances TDP-43 cleavage by apoptotic caspases.

Accumulation of transactive response DNA binding protein (TDP-43) fragments in motor neurons is a post mortem hallmark of different neurodegenerative diseases. TDP-43 fragments are the products of the apoptotic caspases-3 and -7. Either excessive or insufficient cellular Ca(2+) availability is associated with activation of apoptotic caspases.

Cytoplasmic accumulation of TDP-43 in circulating lymphomonocytes of ALS patients with and without TARDBP mutations.

TDP-43, encoded by TARDBP, is a ubiquitously expressed, primarily nuclear protein. In recent years, TDP-43 has been identified as the major pathological protein in ALS due to its mislocalisation in the cytoplasm of motor neurons of patients with and without TARDBP mutations and expression in forms that do not match its predicted molecular weight. In this study, the TDP-43 profile was investigated using western immunoblot analysis in whole lysates, nuclei and cytoplasm of circulating lymphomonocytes from 16 ALS patients, 4 with (ALS/TDP+) and 12 without (ALS/TDP-) TARDBP mutations in the protein C-terminal domain, and thirteen age-matched, healthy donors (controls).

In CD28-costimulated human naïve CD4+ T cells, I-κB kinase controls the expression of cell cycle regulatory proteins via interleukin-2-independent mechanisms.

Stimulation of naïve CD4(+) T cells through engagement of the T-cell receptor (TCR) and the CD28 co-receptor initiates cell proliferation which critically depends on interleukin (IL)-2 secretion and subsequent autocrine signalling via the IL-2 receptor. However, several studies indicate that in CD28-costimulated T cells additional IL-2-independent signals are also required for cell proliferation. In this study, using a neutralizing anti-human IL-2 antibody and two selective, structurally unrelated, cell-permeable I-κB kinase (IKK) inhibitors, BMS-345541 and PS-1145, we show that in human naïve CD4(+) T cells stimulated through a short engagement of the TCR and the CD28 co-receptor, IKK controls the expression of the cell cycle regulatory proteins cyclin D3, cyclin E and cyclin-dependent kinase 2 (CDK2) and the stability of the F-box protein S-phase kinase-associated protein 2 (SKP2) and its co-factor CDC28 protein kinase regulatory subunit 1B (CKS1B), through IL-2-independent mechanisms.

Deregulated sphingolipid metabolism and membrane organization in neurodegenerative disorders.

Sphingolipids are polar membrane lipids present as minor components in eukaryotic cell membranes. Sphingolipids are highly enriched in nervous cells, where they exert important biological functions. They deeply affect the structural and geometrical properties and the lateral order of cellular membranes, modulate the function of several membrane-associated proteins, and give rise to important intra- and extracellular lipid mediators.

N-CAM dysfunction and unexpected accumulation of PSA-NCAM in brain of adult-onset autosomal-dominant leukodystrophy.

Previously, myelin from cerebral white matter (CWM) of two subjects of a family with orthochromatic adult-onset autosomal-dominant leukodystrophy (ADLD) was disclosed to exhibit defective large isoform of myelin-associated glycoprotein (L-MAG) and patchy distribution only in the elder subject. L-MAG and neural cell adhesion molecule (N-CAM) (N-CAM 180, 140, and 120) are structurally related and concur to myelin/axon interaction. In early developmental stages, in neurons and glia N-CAM is converted into polysialylated (PSA)-NCAM by two sialyltransferases sialyltransferase-X (STX) and polysialyltransferase-1 (PST).

TDP-43 redistribution is an early event in sporadic amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder consisting of progressive loss of motor neurons. TDP-43 has been identified as a component of ubiquitin-immunoreactive inclusions of motor neurons in ALS. We focused on the diffuse cytoplasmic TDP-43 immunoreactivity in ALS neurons, and quantitatively assessed it in comparison with skein/round TDP-43 and ubiquitin immunostaining in motor neurons of 30 sporadic ALS cases.

Pregnancy induces molecular alterations reflecting impaired insulin control over glucose oxidative pathways that only in women with a family history of Type 2 diabetes last beyond pregnancy.

In circulating lymphomonocytes (CLM) of patients with Type 2 diabetes (DM2) pyruvate dehydrogenase (PDH), the major determinant of glucose oxidative breakdown, is affected by a cohort of alterations reflecting impaired insulin stimulated glucose utilization. The cohort is also expressed, although incompletely, in 40% of healthy young subjects with a DM2-family history (FH). Pregnancy restrains glucose utilization in maternal peripheral tissues to satisfy fetal requirements.

Alterations of myelin-specific proteins and sphingolipids characterize the brains of acid sphingomyelinase-deficient mice, an animal model of Niemann-Pick disease type A.

Niemann-Pick disease (NPD) type A is a neurodegenerative disorder caused by sphingomyelin (SM) accumulation in lysosomes relying on reduced or absent acid sphingomyelinase (ASM) activity. NPD-A patients develop progressive neurodegeneration including cerebral and cerebellar atrophy, relevant Purkinje cell and myelin deficiency with death within 3 years. ASM'knock-out' (ASMKO) mice, an animal model of NPD-A, develop a phenotype largely mimicking that of NPD-A.

Characterization of the 20S proteasome in human glioblastomas.

Proteasomes are multisubunit proteases involved in many cellular processes, including tumorigenesis and immune surveillance. In their catalytic core, the 20S proteasome, the beta1, beta2 and beta5 subunits show peptidylglutamyl peptide hydrolyzing (PGPH), trypsin-like and chymotrypsin-like activities, respectively. By IFN-gamma and TNFalpha stimulus, these subunits are replaced by their counterparts LMP2, MECL-1 and LMP7, defined inducible subunits, thus originating the immunoproteasome, and expression of the proteasome activator PA28 is enhanced.

Myelin-associated glycoprotein is altered in a familial late-onset orthochromatic leukodystrophy.

Adult-onset dominant leukodystrophies are a heterogeneous group of rare disorders, whose etiology, pathogenesis and molecular background are still unknown. We report the neuropathological and biochemical investigations of the brains and their myelin proteins components in 2 members of an Italian family affected by an adult-onset autosomal dominant leukoencephalopathy. Clinical signs included spastic paraparesis, pseudobulbar syndrome, action tremor of head and hands, and moderate memory impairment.

The HIV protease inhibitors nelfinavir and saquinavir, but not a variety of HIV reverse transcriptase inhibitors, adversely affect human proteasome function.

Background: In HIV-infected patients some clinical and immunological benefits of antiretroviral therapy, which frequently include a combination of HIV protease inhibitors (PIs) and reverse transcriptase inhibitors (RTIs), cannot be solely explained by the drugs' action on viral enzymes. Proteasomes constitute the central protease of the ubiquitin ATP-dependent pathway involved in many cellular processes, as well as in HIV maturation and aggressiveness.

Objective: To explore whether the PIs nelfinavir and saquinavir and the RTIs abacavir, nevirapine, delavirdine, stavudine and didanosine affect proteasome function in vitro and in vivo.