Zhiqiang Ning

Naringenin and hesperetin, two flavonoids derived from Citrus aurantium up-regulate transcription of adiponectin.

The dried, immature fruit of Citrus aurantium L., ‘Zhiqiao’ in Chinese, has been used to treat cardiovascular diseases in traditional Chinese medicine for centuries. Naringenin and hesperetin and their glycosides present in considerable amounts (about 10∼15%) in the herb. The aim of this study is to test whether naringenin and hesperetin influence adiponectin expression, which plays an important role in glucose and lipid metabolism with antiatherogenic and anti‐inflammatory properties. Treatment with naringenin and hesperetin enhanced adiponectin transcription in differentiated 3T3‐L1 cells. Both naringenin and hesperetin induced peroxisome proliferator‐activated receptor (PPAR)γ‐controlled luciferase expression in a dose‐dependent manner (20–160 µM), whereas only naringenin possessed significant activity to activate PPARα. These results suggested the two flavonoids might exert antiatherogenic effects partly through activating PPAR and up‐regulating adiponectin expression in adipocytes. Our findings give new insight for the molecular explanations for the therapeutic effects of Zhiqiao. Copyright

The PPARα/γ dual agonist chiglitazar improves insulin resistance and dyslipidemia in MSG obese rats

1 The aim of this study was to investigate the capacity of chiglitazar to improve insulin resistance and dyslipidemia in monosodium L‐glutamate (MSG) obese rats and to determine whether its lipid‐lowering effect is mediated through its activation of PPARα. 2 Chiglitazar is a PPARα/γ dual agonist. 3 The compound improved impaired insulin and glucose tolerance; decreased plasma insulin level and increased the insulin sensitivity index and decreased HOMA index. Euglycemic hyperinsulinemic clamp studies showed chiglitazar increased the glucose infusion rate in MSG obese rats. 4 Chiglitazar inhibited alanine gluconeogenesis, lowered the hepatic glycogen level in MSG obese rats. Like rosiglitazone, chiglitazar promoted the differentiation of adipocytes and decreased the maximal diameter of adipocytes. In addition, chiglitazar decreased the fibrosis and lipid accumulation in the islets and increased the size of islets. 5 Chiglitazar reduced plasma triglyceride, total cholesterol (TCHO), nonesterified fatty acids (NEFA) and low density lipoprotein‐cholesterol levels; lowered hepatic triglyceride and TCHO contents; decreased muscular NEFA level. Unlike rosiglitazone, chiglitazar showed significant increase of mRNA expression of PPARα, CPT1, BIFEZ, ACO and CYP4A10 in the liver of MSG obese rats. 6 These data suggest that PPARα/γ coagonist, such as chiglitazar, affect lipid homeostasis with different mechanisms from rosiglitazone, chiglitazar may have better effects on lipid homeostasis in diabetic patients than selective PPARγ agonists.

Quantitative structure-activity relationship study of histone deacetylase inhibitors

Histone deacetylases (HDACs) play a critical role in gene transcription and have become a novel target for the discovery of drugs against cancer and other diseases. During the past several years there have been extensive efforts in the identification and optimization of histone deacetylase inhibitors (HDACIs) as novel anticancer drugs. Here we report a comprehensive quantitative structure-activity relationship (QSAR) study of HDACIs in the hope of identifying the structural determinants for anticancer activity. We have identified, collected, and verified the structural and biological activity data for 124 compounds from various literature sources and performed an extensive QSAR study on this comprehensive data set by using various QSAR and classification methods. A highly predictive QSAR model with R(2) of 0.76 and leave-one-out cross-validated R(2) of 0.73 was obtained. The overall rate of cross-validated correct prediction of the classification model is around 92%. The QSAR and classification models provided direct guidance to our internal programs of identifying and optimizing HDAC inhibitors. Limitations of the models were also discussed.

Discovery of an orally active subtype-selective HDAC inhibitor, chidamide, as an epigenetic modulator for cancer treatment

Tumorigenesis is maintained through a complex interplay of multiple cellular biological processes and is regulated to some extent by epigenetic control of gene expression. Targeting one signaling pathway or biological function in cancer treatment often results in compensatory modulation of others, such as off-target drivers of cell survival. As a result, overall survival of cancer patients is still far from satisfactory. Epigenetic-modulating agents can concurrently target multiple aberrant or compensatory signaling pathways found in cancer cells. However, existing epigenetic-modulating agents in cancer treatment have not yet fully translated into survival benefits beyond hematological tumors. In this article, we present a historical rationale for use of chidamide (CS055/Epidaza), an orally active and subtype-selective histone deacetylase (HDAC) inhibitor of the benzamide chemical class. This compound was discovered and successfully developed as mono-therapy for relapsed and refractory peripheral T cell lymphoma (PTCL) in China. We discuss the evidence supporting chidamide as a durable epigenetic modulator that allows cellular reprogramming with little cytotoxicity in cancer treatments.

Pharmacokinetic Optimization of Class-Selective Histone Deacetylase Inhibitors and Identification of Associated Candidate Predictive Biomarkers of Hepatocellular Carcinoma Tumor Response

Herein, we describe the pharmacokinetic optimization of a series of class-selective histone deacetylase (HDAC) inhibitors and the subsequent identification of candidate predictive biomarkers of hepatocellular carcinoma (HCC) tumor response for our clinical lead using patient-derived HCC tumor xenograft models. Through a combination of conformational constraint and scaffold hopping, we lowered the in vivo clearance (CL) and significantly improved the bioavailability (F) and exposure (AUC) of our HDAC inhibitors while maintaining selectivity toward the class I HDAC family with particular potency against HDAC1, resulting in clinical lead 5 (HDAC1 IC₅₀ = 60 nM, mouse CL = 39 mL/min/kg, mouse F = 100%, mouse AUC after single oral dose at 10 mg/kg = 6316 h·ng/mL). We then evaluated 5 in a biomarker discovery pilot study using patient-derived tumor xenograft models, wherein two out of the three models responded to treatment. By comparing tumor response status to compound tumor exposure, induction of acetylated histone H3, candidate gene expression changes, and promoter DNA methylation status from all three models at various time points, we identified preliminary candidate response prediction biomarkers that warrant further validation in a larger cohort of patient-derived tumor models and through confirmatory functional studies.

In Vitro and In Vivo Characterizations of Chiglitazar, a Newly Identified PPAR Pan-Agonist

Solid rationales are still present for the identification of synthetic ligands to simultaneously target multiple PPAR subtypes for the treatment of T2DM. The purpose of this study was to characterize the in vitro and in vivo differential effects of chiglitazar, a non-TZD type of PPAR pan-agonist currently in phase III clinic development in China, from PPARγ-selective agonist like rosiglitazone. Chiglitazar showed transactivating activity in each PPARα, γ, and δ subtype and upregulated the expression of PPARα and/or PPARδ downstream genes involved in the key processes of lipid metabolism and thermogenesis. Comparable blood glucose lowering effect was observed between chiglitazar and rosiglitazone, but chiglitazar did not significantly increase the body weight in KKAy and fat pad weight in db/db mice. Chiglitazar had high distribution in liver, pancreas, and skeleton muscles but was less present in kidney, heart, and adipose in rats. Heart weight increase was not observed in rats treated with chiglitazar for 6 months at a dose as high as 45 mg kg−1. The in vitro and in vivo differential features of chiglitazar are informative and encouraging for the further development of this synthetic ligand for the potential use in T2DM.

CS2164, a novel multi‐target inhibitor against tumor angiogenesis, mitosis and chronic inflammation with anti‐tumor potency

Although inhibitors targeting tumor angiogenic pathway have provided improvement for clinical treatment in patients with various solid tumors, the still very limited anti‐cancer efficacy and acquired drug resistance demand new agents that may offer better clinical benefits. In the effort to find a small molecule potentially targeting several key pathways for tumor development, we designed, discovered and evaluated a novel multi‐kinase inhibitor, CS2164. CS2164 inhibited the angiogenesis‐related kinases (VEGFR2, VEGFR1, VEGFR3, PDGFRα and c‐Kit), mitosis‐related kinase Aurora B and chronic inflammation‐related kinase CSF‐1R in a high potency manner with the IC50 at a single‐digit nanomolar range. Consequently, CS2164 displayed anti‐angiogenic activities through suppression of VEGFR/PDGFR phosphorylation, inhibition of ligand‐dependent cell proliferation and capillary tube formation, and prevention of vasculature formation in tumor tissues. CS2164 also showed induction of G2/M cell cycle arrest and suppression of cell proliferation in tumor tissues through the inhibition of Aurora B‐mediated H3 phosphorylation. Furthermore, CS2164 demonstrated the inhibitory effect on CSF‐1R phosphorylation that led to the suppression of ligand‐stimulated monocyte‐to‐macrophage differentiation and reduced CSF‐1R+ cells in tumor tissues. The in vivo animal efficacy studies revealed that CS2164 induced remarkable regression or complete inhibition of tumor growth at well‐tolerated oral doses in several human tumor xenograft models. Collectively, these results indicate that CS2164 is a highly selective multi‐kinase inhibitor with potent anti‐tumor activities against tumor angiogenesis, mitosis and chronic inflammation, which may provide the rationale for further clinical assessment of CS2164 as a therapeutic agent in the treatment of cancer.

Chiglitazar Preferentially Regulates Gene Expression via Configuration-Restricted Binding and Phosphorylation Inhibition of PPARγ

Type 2 diabetes mellitus is often treated with insulin-sensitizing drugs called thiazolidinediones (TZD), which improve insulin resistance and glycemic control. Despite their effectiveness in treating diabetes, these drugs provide little protection from eminent cardiovascular disease associated with diabetes. Here we demonstrate how chiglitazar, a configuration-restricted non-TZD peroxisome proliferator-activated receptor (PPAR) pan agonist with moderate transcription activity, preferentially regulates ANGPTL4 and PDK4, which are involved in glucose and lipid metabolism. CDK5-mediated phosphorylation at serine 273 (S273) is a unique regulatory mechanism reserved for PPARγ, and this event is linked to insulin resistance in type 2 diabetes mellitus. Our data demonstrates that chiglitazar modulates gene expression differently from two TZDs, rosiglitazone and pioglitazone, via its configuration-restricted binding and phosphorylation inhibition of PPARγ. Chiglitazar induced significantly greater expression of ANGPTL4 and PDK4 than rosiglitazone and pioglitazone in different cell models. These increased expressions were dependent on the phosphorylation status of PPARγ at S273. Furthermore, ChIP and AlphaScreen assays showed that phosphorylation at S273 inhibited promoter binding and cofactor recruitment by PPARγ. Based on these results, activities from pan agonist chiglitazar can be an effective part of a long-term therapeutic strategy for treating type 2 diabetes in a more balanced action among its targeted organs.

An Integrated Biochemoinformatics System for Drug Discovery

Chipscreen Biosciences, Ltd. (www.chipscreen.com) is a drug discovery company specialized in novel small molecule therapeutics. Chipscreen has developed a proprietary chemical genomics approach to accelerate the discovery of new medicines from its collection of natural products, traditional Chinese medicines, and synthetic chemical libraries. Central to its drug discovery platform is Chipscreen’s capability of integrating in silico drug design, chemical synthesis, unique parallel multi-target high throughput screening, global gene expression profiling, and informatics to rapidly and effectively advance the drug discovery process. To fulfill Chipscreen’s drug discovery needs, we have developed an integrated biochemoinformatics system to efficiently manage and mine various types of experimental data, including chemical structure information, biological activity fingerprints, and gene expression profiling patterns. Well-informed decision on which drug candidates should be advanced into preclinical and clinical development can be made by maximizing the utilities of experimental data stored in the database, thereby lowering the risk and increasing the success rate of the drug discovery and development process.