Jiyue Zheng

Design, synthesis and evaluation of a series of non-steroidal anti-inflammatory drug conjugates as novel neuroinflammatory inhibitors

Neuroinflammation is involved in the process of several central nervous system (CNS) diseases such as Parkinsons disease, Alzheimers disease, ischemia and multiple sclerosis. As the macrophages in the central nervous system, microglial cell function in the innate immunity of the brain and are largely responsible for the inflammation-mediated neurotoxicity. Prevention of microglia activation might alleviate neuronal damage and degeneration under the inflammatory conditions, and therefore, represents a possible therapeutic approach to the aforementioned CNS diseases. Here we report the synthesis of a number of non-steroidal anti-inflammatory drug (NSAID) conjugates, and the evaluation of their anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells and primary mouse microglial cells. Among the tested analogues, compounds 8 and 11 demonstrated potent inhibition of nitric oxide production with no or weak cell toxicity. Compound 8 also significantly suppressed the expression of tumor necrosis factor (TNF)-α, interleukin (IL)-6, cyclooxygenase (COX)-2 as well as inducible nitric oxide synthase (iNOS) in LPS-stimulated BV-2 microglial cells. Further mechanistic studies indicated that compound 8 significantly suppressed phosphorylation of mitogen-activated protein kinases (MAPKs) and subsequent activation of activator of transcription 1 (AP-1). Furthermore, in a co-culture system, compound 8 inhibited the cytotoxicity generated by LPS-activated microglia toward HT-22 neuroblastoma cells. Collectively, these experimental results demonstrated that compound 8 possessed potent anti-neuroinflammatory activity via inhibition of microglia activation, and might serve as a potential lead for the therapeutic treatment of neuroinflammatory diseases.

Design, synthesis, and structure--activity-relationship of tetrahydrothiazolopyridine derivatives as potent smoothened antagonists.

The Smoothened (Smo) receptor is an important component of the hedgehog (Hh) signaling pathway, which plays a critical role during embryonic development. In adults, Hh signaling is curtailed and has limited functions such as stem cell maintenance and tissue repair. However, aberrant activity of the Hh signaling in adults has been linked to numerous human cancers. Inhibition of Smo leads to the blockade of Hh signaling, and therefore represents a promising approach toward novel anticancer therapy. Through scaffold morphing of a few known Smo antagonists, a series of novel tetrahydrothiazolopyridine derivatives were developed. Compounds from this new scaffold demonstrated excellent Hh signaling inhibition which was comparable to or better than that of Vismodegib. Further, compound 30 exhibited a lower melting point and a moderately improved solubility compared with those of Vismodegib; compounds 11 and 30 showed good pharmacokinetic profiles with 34% and 77% oral bioavailability in rat, respectively. Collectively, these results strongly support further optimization of this novel scaffold to develop better Smo antagonists.

Discovery of a 6-(pyridin-3-yl)benzo[d]thiazole template for optimization of hedgehog and PI3K/AKT/mTOR dual inhibitors

Vismodegib is the first FDA approved cancer therapy based on inhibition of aberrant hedgehog signaling. Like most cancer therapies, vismodegib suffered from resistance, even during clinical development. Numerous reports demonstrated that simultaneous blockage of hedgehog and PI3K/AKT/mTOR pathways resulted in significantly superior outcomes compared with single agent alone in a number of animal disease models. The dual hedgehog and PI3K/AKT/mTOR inhibition represented a promising approach not only to overcoming the resistance but also to delaying its onset. Here we report a series of compounds based on a 6-(pyridin-3-yl)benzo[d]thiazole template which have demonstrated significant inhibition of both hedgehog and PI3K/AKT/mTOR signaling pathways. This new scaffold can serve as a lead for further optimization.

Scaffold hopping approach to a new series of smoothened antagonists

The hedgehog (Hh) signaling pathway is a key regulator during embryonic development, while in adults, it has limited functions such as stem cell maintenance and tissue repair. The aberrant activity of the Hh signaling in adults has been linked to numerous human cancers. Inhibition of Hh signaling therefore represents a promising approach toward novel anticancer therapies. The Smoothened (Smo) receptor mediates Hh signaling. Here we report a new series of Smo antagonists which were obtained by a scaffold hopping strategy. Compounds from this new scaffold demonstrated decent inhibition of Hh pathway signaling. The new scaffold can serve as a starting point for further optimization.

Optimization of 6-Heterocyclic-2-(1H-pyrazol-1-yl)-N-(pyridin-2-yl)pyrimidin-4-amine as Potent Adenosine A2A Receptor Antagonists for the Treatment of Parkinson’s Disease

Parkinsons disease is a neurodegenerative disease characterized by the motor symptoms of bradykinesia, tremor, and rigidity. Current therapies are based mainly on dopaminergic replacement strategies by administration of either dopamine agonists or dopamine precursor levodopa (L-Dopa). These treatments provide symptomatic relief without slowing or stopping the disease progression, and long-term usage of these drugs is associated with diminished efficacy, motor fluctuation, and dyskinisia. Unfortunately, there had been few novel treatments developed in the past decades. Among nondopaminergic strategies for the treatment of Parkinsons disease, antagonism of the adenosine A2A receptor has emerged to show great potential. Here we report the optimization of a new chemical scaffold, which achieved exceptional receptor binding affinity and ligand efficiency against adenosine A2A receptor. The leading compounds demonstrated excellent efficacy in the haloperidol induced catalepsy model for Parkinsons disease.

Exploration of the linkage elements of porcupine antagonists led to potent Wnt signaling pathway inhibitors.

The Wnt signaling pathway is a pivotal developmental pathway. It operates through control of cellular functions such as proliferation, differentiation, migration and polarity. Aberrant Wnt signaling has been implicated in the formation and metastasis of tumors. Porcupine is a component of the Wnt signaling pathway. It is a member of the membrane-bound O-acyltransferase family of proteins. Porcupine catalyzes the palmitoylation of Wnt proteins, a process which is essential to their secretion and activity. Here we report a novel series of compounds obtained by a scaffold hybridization strategy from two known porcupine inhibitor classes. The leading compound 62 demonstrated subnanomolar (IC50 0.11 nM) inhibition of Wnt signaling in a paracrine cellular reporter gene assay. Compound 62 also potently inhibited Wnt secretion into culture medium, an indication of direct inhibition of the porcupine protein. Furthermore, compound 62 showed excellent chemical, plasma and liver microsomal stabilities. Collectively, these results strongly support further optimization of this novel scaffold to develop better Wnt pathway inhibitors.

Replacement of amide with bioisosteres led to a new series of potent adenosine A2A receptor antagonists

We have previously reported a series of 2,4,6-trisubstituted pyrimidines as potent A2A receptor antagonists. The leading compounds often feature a potentially labile acetamide functional group which tends to hydrolyze under acidic conditions. Here we report the replacement of the acetamide functional group with bioisosteres. This effort led us to a new series of adenosine A2A receptor antagonists with improved potency and chemical stability.

Design, Synthesis, and Structure–Activity Relationship of Tetrahydropyrido[4,3-d]pyrimidine Derivatives as Potent Smoothened Antagonists with in Vivo Activity

Medulloblastoma is one of the most prevalent brain tumors in children. Aberrant hedgehog (Hh) pathway signaling is thought to be involved in the initiation and development of medulloblastoma. Vismodegib, the first FDA-approved cancer therapy based on inhibition of aberrant hedgehog signaling, targets smoothened (Smo), a G-protein coupled receptor (GPCR) central to the Hh pathway. Although vismodegib exhibits promising therapeutic efficacy in tumor treatment, concerns have been raised from its nonlinear pharmacokinetic (PK) profiles at high doses partly due to low aqueous solubility. Many patients experience adverse events such as muscle spasms and weight loss. In addition, drug resistance often arises among tumor cells during treatment with vismodegib. There is clearly an urgent need to explore novel Smo antagonists with improved potency and efficacy. Through a scaffold hopping strategy, we have identified a series of novel tetrahydropyrido[4,3-d]pyrimidine derivatives, which exhibited effective inhibition of Hh signaling. Among them, compound 24 is three times more potent than vismodegib in the NIH3T3-GRE-Luc reporter gene assay. Compound 24 has a lower melting point and much greater solubility compared with vismodegib, resulting in linear PK profiles when dosed orally at 10, 30, and 100 mg/kg in rats. Furthermore, compound 24 showed excellent PK profiles with a 72% oral bioavailability in beagle dogs. Compound 24 demonstrated overall favorable in vitro safety profiles with respect to CYP isoform and hERG inhibition. Finally, compound 24 led to significant regression of subcutaneous tumor generated by primary Ptch1-deficient medulloblastoma cells in SCID mouse. In conclusion, tetrahydropyrido[4,3-d]pyrimidine derivatives represent a novel set of Smo inhibitors that could potentially be utilized to treat medulloblastoma and other Hh pathway related malignancies.

Design, synthesis, and evaluation of potent Wnt signaling inhibitors featuring a fused 3-ring system

The Wnt signaling pathway is a critical developmental pathway which operates through control of cellular functions such as proliferation and differentiation. Aberrant Wnt signaling has been linked to the formation and metastasis of tumors. Porcupine, a member of the membrane-bound O-acyltransferase family of proteins, is an important component of the Wnt pathway. Porcupine catalyzes the palmitoylation of Wnt proteins, a process needed for their secretion and activity. Here we report a novel series of compounds obtained by a scaffold hybridization strategy from a known porcupine inhibitor class. The leading compound 59 demonstrated subnanomolar inhibition of Wnt signaling in a paracrine cellular assay. Compound 59 also showed excellent chemical, plasma and liver microsomal stabilities. Furthermore, compound 59 exhibited good pharmacokinetic profiles with 30% oral bioavailability in rat. Collectively, these results strongly support further optimization of this novel scaffold to develop better Wnt pathway inhibitors.

Discovery of potent and novel smoothened antagonists via structure-based virtual screening and biological assays

The Hedgehog (Hh) signaling pathway plays a critical role in controlling patterning, growth and cell migration during embryonic development. Aberrant activation of Hh signaling has been linked to tumorigenesis in various cancers, such as basal cell carcinoma (BCC) and medulloblastoma. As a key member of the Hh pathway, the Smoothened (Smo) receptor, a member of the G protein-coupled receptor (GPCR) family, has emerged as an attractive therapeutic target for the treatment and prevention of human cancers. The recent determination of several crystal structures of Smo in complex with different antagonists offers the possibility to perform structure-based virtual screening for discovering potent Smo antagonists with distinct chemical scaffolds. In this study, based on the two Smo crystal complexes with the best capacity to distinguish the known Smo antagonists from decoys, the molecular docking-based virtual screening was conducted to identify promising Smo antagonists from ChemDiv library. A total of 21 structurally novel and diverse compounds were selected for experimental testing, and six of them exhibited significant inhibitory activity against the Hh pathway activation (IC50 < 10 μM) in a GRE (Gli-responsive element) reporter gene assay. Specifically, the most potent compound (compound 20: 47 nM) showed comparable Hh signaling inhibition to vismodegib (46 nM). Compound 20 was further confirmed to be a potent Smo antagonist in a fluorescence based competitive binding assay. Optimization using substructure searching method led to the discovery of 12 analogues of compound 20 with decent Hh pathway inhibition activity, including four compounds with IC50 lower than 1 μM. The important residues uncovered by binding free energy calculation (MM/GBSA) and binding free energy decomposition were highlighted and discussed. These findings suggest that the novel scaffold afforded by compound 20 can be used as a good starting point for further modification/optimization and the clarified interaction patterns may also guide us to find more potent Smo antagonists.