Quinazoline-based tricyclic compounds that regulate programmed cell death, induce neuronal differentiation, and are curative in animal models for excitotoxicity and hereditary brain disease.

A Vainshtein,I Otradnov,S Singh,A Shterenberg,L Pe’Er,A Avital,B Dutta,S Leschiner,L Veenman,I Marek,B Island,M Gavish,A Weizman,A Masarwa,E Levin,S Zubedat,S Aga-Mizrachi,E Tsoglin,I Maniv

doi:10.1038/cddiscovery.2015.27

Abstract

Expanding on a quinazoline scaffold, we developed tricyclic compounds with biological activity. These compounds bind to the 18 kDa translocator protein (TSPO) and protect U118MG (glioblastoma cell line of glial origin) cells from glutamate-induced cell death. Fascinating, they can induce neuronal differentiation of PC12 cells (cell line of pheochromocytoma origin with neuronal characteristics) known to display neuronal characteristics, including outgrowth of neurites, tubulin expression, and NeuN (antigen known as ‘neuronal nuclei’, also known as Rbfox3) expression. As part of the neurodifferentiation process, they can amplify cell death induced by glutamate. Interestingly, the compound 2-phenylquinazolin-4-yl dimethylcarbamate (MGV-1) can induce expansive neurite sprouting on its own and also in synergy with nerve growth factor and with glutamate. Glycine is not required, indicating that N-methyl-D-aspartate receptors are not involved in this activity. These diverse effects on cells of glial origin and on cells with neuronal characteristics induced in culture by this one compound, MGV-1, as reported in this article, mimic the diverse events that take place during embryonic development of the brain (maintenance of glial integrity, differentiation of progenitor cells to mature neurons, and weeding out of non-differentiating progenitor cells). Such mechanisms are also important for protective, curative, and restorative processes that occur during and after brain injury and brain disease. Indeed, we found in a rat model of systemic kainic acid injection that MGV-1 can prevent seizures, counteract the process of ongoing brain damage, including edema, and restore behavior defects to normal patterns. Furthermore, in the R6-2 (transgenic mouse model for Huntington disease; Strain name: B6CBA-Tg(HDexon1)62Gpb/3J) transgenic mouse model for Huntington disease, derivatives of MGV-1 can increase lifespan by >20% and reduce incidence of abnormal movements. Also in vitro, these derivatives were more effective than MGV-1.

Highlights

The novel tricyclic compounds based on a quinazoline scaffold of this study were tested by us, for example, to attenuate glutamateinduced cell death of the human glioblastoma cell line U118MG and to provide neuroprotective effects in animal models for brain injury and brain disease.[19,20]
Ligand PK 11195 (the classical translocator protein (TSPO) ligand: N-butan-2-yl-1(2-chlorophenyl)-N-methylisoquinoline-3-carboxamide), the affinities (Ki’s) presented in Figure 1a show that the affinities of root name of compounds (MGV)-3 and 2-Cl-2-phenylquinazolin-4-yl diethylcarbamate (MGV-3) are similar to PK 11195 (~2.5 nM), whereas those of 2-phenylquinazolin-4-yl ethyl(methyl)carbamate (MGV-2) and 2-Cl-MGV-2 are one order of magnitude lower, and those of 2-phenylquinazolin-4yl dimethylcarbamate (MGV-1) and 2-Cl-MGV-1 are two orders of magnitude lower (Figure 1a), as determined in rat kidney homogenate, using [3H]PK 11195 as a radiolabeled TSPO ligand
We assumed that our compounds would prevent collapse of the mitochondrial membrane potential (ΔΨm), which is typically induced by glutamate[51] and normally under the control of the TSPO.[4,5]

Summary

Introduction

The 18 kDa translocator protein (TSPO) takes part in various cellular functions, including regulation of cell death and expression of numerous genes.[1,2,3,4,5,6] Associated with these functions the primary locations of the TSPO include mitochondria, and nuclear and perinuclear sites.[1,7,8] TSPO can be found throughout the body in various tissues.[1,9] Moderate expression of TSPO occurs in healthy central nervous system (CNS), which can increase in association with disease and injury, both in glia and in neurons.[10,11,12,13,14] Programmed cell death and cell differentiation, separately as well as combined, constitute basic, general, and essential functions, for example, regarding embryonic development of the brain, and in adults in response to injury and disease, including cancer.[15,16,17] The same is true for gene expression. TSPO function in cell differentiation is becoming more appreciated.[18]

Methods

Results

Conclusion