Discovery of Potent Small-Molecule Inhibitors of WDR5-MYC Interaction

WD repeat domain 5 (WDR5) is a member of the WD40-repeat protein family that plays a critical role in multiple processes. It is also a prominent target for pharmacological inhibition in diseases such as cancer, aging, and neurodegenerative disorders. Interactions between WDR5 and various partners are essential for sustaining its function. Most drug discovery efforts center on the WIN (WDR5 interaction motif) site of WDR5 that is responsible for the recruitment of WDR5 to chromatin. Here, we describe the discovery of novel WDR5 inhibitors for the other WBM (WDR5 binding motif) pocket on this scaffold protein, to disrupt WDR5 interaction with its binding partner MYC by high-throughput biochemical screening, subsequent molecule optimization, and biological assessment. These new WDR5 inhibitors provide useful probes for future investigations of WDR5 and an avenue for targeting WDR5 as a therapeutic strategy.

Access to oncology consultation in a cancer cohort in northeastern Ontario

BACKGROUND

To enhance cancer symptom management for residents of Sudbury-Manitoulin District, an ambulatory palliative clinic (pac) was established at the Northeast Cancer Centre of Health Sciences North. The pac is accessed from a medical or radiation oncology consultation. The primary purpose of the present population-based retrospective study was to estimate the percentage of cancer patients who died without ever having a medical or radiation oncology consultation. A secondary purpose was to determine factors associated with never having received one of those specialized consultations.

METHODS

Administrative data was obtained through the Ontario Cancer Data Linkage Project. For each index case, we constructed a timeline, in days, of all Ontario Health Insurance Plan billing codes and associated service dates starting with the primary cancer diagnosis and ending with death.

RESULTS

Within the 5-year study period (2004-2008), 6683 people in the area of interest with a valid record of primary cancer diagnosis died from any cause. Most (n = 5988, 89.6%) had 1 primary cancer diagnosis. For that subgroup, excluding those with a disease duration of 0 days (n = 67), about 18.4% (n = 1088) never had a consultation with a medical or radiation oncologist throughout their disease trajectory. Patients who were older or who resided in a rural area were significantly less likely to have had a consultation.

CONCLUSIONS

Specific strategies directed toward older and rural patients might help to address this important access-to-care issue.

Effects of the vasopressin (V1b) receptor antagonist, SSR149415, and the corticotropin-releasing factor 1 receptor antagonist, SSR125543, on FG 7142-induced increase in acetylcholine and norepinephrine release in the rat

Arginine vasopressin and corticotropin-releasing factor are two neuroactive peptides that regulate hypothalamic-pituitary-axis and associated stress response. While the potential antidepressant and anxiolytic profiles of corticotropin-releasing factor 1 antagonists have been well studied, the concept of blockade of vasopressin system as another approach for the treatment of emotional processes has only been made available recently by the synthesis of the first non-peptide antagonist at the V1b receptor, SSR149415. In the present study SSR149415 has been compared with the corticotropin-releasing factor 1 antagonist SSR125543 and with anxiolytic and antidepressant drugs on the response of hippocampal cholinergic and cortical noradrenergic systems to the anxiogenic benzodiazepine receptor inverse agonist FG 7142. Acute (0.3-10 mg/kg, i.p.) and long-term administration (10 mg/kg, i.p., 21 days) of SSR149415 and SSR125543 reduced the FG 7142-induced increase in extracellular concentrations of acetylcholine in the hippocampus of anesthetized rats measured by microdialysis. By contrast acute and long-term administration of SSR149415 failed to reduce the FG 7142-induced increase in the release of norepinephrine in the cortex of freely moving rats. The present results demonstrate that the two compounds have similar profiles in a model of activation by an anxiogenic drug of the hippocampal cholinergic system and they suggest that SSR149415 and SSR125543 may have anti-stress anxiolytic and antidepressant effects via a mechanism of action different from classical benzodiazepine ligands and noradrenergic antidepressants.

SL25.1131 [3(S),3a(S)-3-methoxymethyl-7-[4,4,4-trifluorobutoxy]-3,3a,4,5-tetrahydro-1,3-oxazolo[3,4-a]quinolin-1-one], a new, reversible, and mixed inhibitor of monoamine oxidase-A and monoamine oxidase-B: biochemical and behavioral profile

SL25.1131 [3(S),3a(S)-3-methoxymethyl-7-[4,4,4-trifluorobutoxy]-3,3a,4,5-tetrahydro-1,3-oxazolo[3,4-a]quinolin-1-one] is a new, nonselective, and reversible monoamine oxidase (MAO) inhibitor, belonging to a oxazoloquinolinone series. In vitro studies showed that SL25.1131 inhibits rat brain MAO-A and MAO-B with IC50 values of 6.7 and 16.8 nM and substrate-dependent Ki values of 3.3 and 4.2 nM, respectively. In ex vivo conditions, the oral administration of SL25.1131 induced a dose-dependent inhibition of MAO-A and MAO-B activities in the rat brain with ED50 values of 0.67 and 0.52 mg/kg, respectively. In the rat brain, duodenum, and liver, the inhibition of MAO-A and MAO-B by SL25.1131 (3.5 mg/kg p.o.) was reversible, and the recovery of MAO-A and MAO-B activities was complete 16 h after administration. SL25.1131 (3.5 mg/kg p.o.) increased tissue levels of dopamine (DA), norepinephrine, and 5-hydroxytryptamine and decreased levels of their deaminated metabolites 3,4-dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindolacetic acid. In mice, SL25.1131 induced a dose-dependent potentiation of 5-hydroxytryptophan-induced tremors and phenylethylamine-induced stereotypies with ED50 values of 0.60 and 2.8 mg/kg p.o., respectively. SL25.1131 was able to reestablish normal striatal dopaminergic tone and locomotor activity in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned mice. In addition, when coadministered with L-DOPA, SL25.1131 increased the available DA in the striatum and the duration of L-DOPA-induced hyperactivity. The duration of the effect of L-DOPA on circling behavior in 6-hydroxydopamine-lesioned rats was also increased. The neurochemical profile of SL25.1131 demonstrates that this compound is a mixed, potent, and reversible MAO-A/B inhibitor in vitro, in vivo, and ex vivo. SL25.1131 has therapeutic potential as a symptomatic treatment during the early phase of Parkinson's disease and as an adjunct to L-DOPA therapy during the early and late phases of the disease.

Evaluation of simple and complex sensorimotor behaviours in rats with a partial lesion of the dopaminergic nigrostriatal system

We have examined the behavioural consequences of a partial unilateral dopaminergic denervation of the rat striatum. This partial lesion was obtained by an intrastriatal 6-hydroxy-dopamine injection (6-OHDA, 20 or 10 microgram divided between two injection sites) and was compared with a unilateral complete lesion resulting from an injection of 6-OHDA (2 x 6 microgram) into the medial forebrain bundle. Quantification of striatal dopamine (DA) and its metabolites, and the immunohistochemical evaluation of the nigrostriatal DA system confirmed the complete and partial lesions. Animals with complete striatal denervation displayed both apomorphine- and amphetamine-induced rotations whereas the partial denervation elicited amphetamine-induced rotations only. However, the rates of amphetamine-induced rotation were not correlated with the size of the lesion. In contrast, the paw-reaching impairments were significantly correlated with the striatal dopaminergic depletion. When evaluated in the staircase test, animals with partial denervation were impaired exclusively for the paw contralateral to the side of the lesion. This motor deficit (50-75%) included all components of the skilled paw use (i.e. attempt, motor coordination and success) and was observed at least 12 weeks after the lesion. However, these animals were able to perform normal stepping adjustments with the impaired paw, indicating that the partial lesion induced a coordination deficit of the paw rather than a deficit of movement initiation. After a complete lesion, stepping adjustments of the contralateral paw were dramatically impaired (by 80%), an akinesia which almost certainly accounted for the great deficit in skilled paw use. The paw-reaching impairments resulting from the partial striatal denervation are proposed as a model of the early symptoms of Parkinson's disease and may be useful for the development of restorative therapies.

Aspirin and salicylate protect against MPTP-induced dopamine depletion in mice

The neurotoxic effects of the dopamine-selective neurotoxin MPTP (15 mg/kg, s.c.), in mice, were totally prevented by systemic administration of salicylate (ED50 = 40 mg/kg, i.p.), aspirin (ED50 = 60 mg/kg, i.p.), or the soluble lysine salt of aspirin, Aspegic (ED50 = 80 mg/kg, i.p.). The protective effects of aspirin are unlikely to be related to cyclooxygenase inhibition as paracetamol (100 mg/kg, i.p.), diclofenac (100 mg/kg, i.p.), ibuprofen (20 mg/kg, i.p.) and indomethacin (100 mg/kg, i.p.) were ineffective. Dexamethasone (3-30 mg/kg, i.p.), which, like aspirin and salicylate, has been reported to inhibit the transcription factor NF-kappaB, was also ineffective. Aspirin or salicylate (100 microM) had no effect on dopamine uptake into striatal synaptosomes or on monoamine oxidase B activity. The neuroprotective effects of salicylate derivatives could perhaps be related to hydroxyl radical scavenging. This was suggested by the fact that hydroxylated metabolites of salicylate (2,3- and 2,5-dihydrobenzoic acid) were recovered in brain tissue following the combined administration of MPTP and aspirin to a greater extent than following aspirin alone. The surprising neuroprotective effects of aspirin in an animal model of Parkinson's disease warrant further clinical investigation.

Befloxatone, a new reversible and selective monoamine oxidase-A inhibitor. I. Biochemical profile

Befloxatone, a novel oxazolidinone derivative, inhibited selectively and competitively monoamine oxidase (MAO)-A in human and rat brain, heart, liver and duodenum homogenates with Ki values ranging from 1.9 to 3.6 nM for MAO-A and from 270 to 900 nM for MAO-B. In vitro, befloxatone was more potent at inhibiting MAO-A activity than reference compounds (befloxatone > harmaline > brofaromine > BW 137OU87 > RS 8359 > toloxatone > moclobemide). The inhibition of MAO-A by befloxatone was time-dependent and fully reversible after dilution. After p.o. administration, befloxatone induced a dose-dependent and selective inhibition of rat brain and duodenum MAO-A activities ex vivo with ED50 values of 0.06 and 0.025 mg/kg, respectively. Befloxatone (0.5 mg/kg p.o.) decreased MAO-B activity by only 20% in both tissues. In the brain, liver and duodenum, the inhibition of MAO-A activity by befloxatone was short lasting. Twenty-four hours after administration of befloxatone (0.75 mg/kg p.o.), a full recovery of MAO-A activity was observed in the brain, but the enzyme activity was still decreased by 38 and 56% in the duodenum and liver, respectively. In the rat brain, befloxatone (0.75 mg/kg p.o.) increased levels of norepinephrine, dopamine and 5-hydroxytryptamine and decreased levels of their respective deaminated metabolites. These variations were dose-dependent and reversed 24 hr after administration. In addition, befloxatone (0.75 mg/kg p.o.) decreased free 3,4-dihydroxyphenylethylene glycol levels in the brain and plasma. Befloxatone (10 microM) did not modify the activities of diamine or benzylamine oxidase and did not interact with monoamine uptake mechanisms or with a variety of neurotransmitter or drug receptor sites. In conclusion, the neurochemical profile of befloxatone demonstrates that this compound is a selective, competitive, potent and reversible MAO-A inhibitor.