Cambinol, a Novel Inhibitor of Neutral Sphingomyelinase 2 Shows Neuroprotective Properties

Abstract

Ceramide is a bioactive lipid that plays an important role in stress responses leading to apoptosis, cell growth arrest and differentiation. Ceramide production is due in part to sphingomyelin hydrolysis by sphingomyelinases. In brain, neutral sphingomyelinase 2 (nSMase2) is expressed in neurons and increases in its activity and expression have been associated with pro-inflammatory conditions observed in Alzheimer’s disease, multiple sclerosis and human immunodeficiency virus (HIV-1) patients. Increased nSMase2 activity translates into higher ceramide levels and neuronal cell death, which can be prevented by chemical or genetic inhibition of nSMase2 activity or expression. However, to date, there are no soluble, specific and potent small molecule inhibitor tool compounds for in vivo studies or as a starting point for medicinal chemistry optimization. Moreover, the majority of the known inhibitors were identified using bacterial, bovine or rat nSMase2. In an attempt to identify new inhibitor scaffolds, two activity assays were optimized as screening platform using the recombinant human enzyme. First, active hits were identified using a fluorescence-based high throughput compatible assay. Then, hits were confirmed using a 14C sphingomyelin-based direct activity assay. Pharmacologically active compounds and approved drugs were screened using this strategy which led to the identification of cambinol as a novel uncompetitive nSMase2 inhibitor (K i = 7 μM). The inhibitory activity of cambinol for nSMase2 was approximately 10-fold more potent than for its previously known target, silence information regulator 1 and 2 (SIRT1/2). Cambinol decreased tumor necrosis factor-α or interleukin-1 β-induced increases of ceramide and cell death in primary neurons. A preliminary study of cambinol structure and activity allowed the identification of the main structural features required for nSMase2 inhibition. Cambinol and its analogs may be useful as nSMase2 inhibitor tool compounds to prevent ceramide-dependent neurodegeneration.

HIV-associated neurocognitive disorder — pathogenesis and prospects for treatment

“…These disruptions in cellular energetics could explain abnormal accumulation of sphingolipids and proteins, such as amyloid-β, in dysfunctional endolysosomal compartments 72,75,76,80,127–129 : reduced or modified cellular energy production would impair the function of the proton pumps that are dependent on adenosine triphosphate (ATP) — these pumps are necessary to maintain an acidic luminal pH, which is required for efficient functioning of >50 hydrolytic enzymes in lysosomes that degrade cellular products 128,130,131 . The discussed studies have identified several possible targets for therapeutic intervention that include modulators of glucose metabolism (intranasal insulin), ceramide metabolism 72,132,133 and endolysosomal function 131 . Small-molecule therapeutics designed to affect these targets are in early to mid-stage development 131,134 , and a clinical trial is planned to determine the effectiveness of intranasal insulin to treat ANI and MND in HIV+ patients.…”

Polymer-based precipitation preserves biological activities of extracellular vesicles from an endometrial cell line

“…In fact, previous studies showed that the IC 50 of GW4869 and Cambinol are 1 and 5 μM respectively [33,65]. Thus, at the same concentration, GW4869 is more effective than Cambinol.…”

“…Cambinol is another inhibitor of neutral sphingomyelinase 2, which blocks exosome production [33]. Similar to GW4869, the Ishikawa cells were treated with cambinol at concentrations of 0.1 μM, 1 μM, 10 μM or 30 μM in 5% EVs-depleted-BSA for 48 hours and the EVs were isolated by PBP.…”

Role of sphingomyelinases in neurological disorders

“…Nevertheless, screening of pharmacologically active compounds for activity against human N-SMase2 has led to the identification of cambinol as a novel uncompetitive N-SMase2 inhibitor. Cambinol modulates TNF-a or IL-1b-induced increase in ceramide and cell death in primary neurons, suggesting it could prevent ceramide-dependent neurodegeneration [200]. The above inhibitors could be valuable lead compounds for development as potent and tolerable inhibitors of aSMase and N-SMase, that can cross the blood--brain barrier.…”