Type 2 Diabetes (T2D) affects more than 300 million individuals globally. Beta cell dysfunction and death are key elements in the pathogenesis of both type 1 and type 2 diabetes. Endoplasmic reticulum (ER) stress plays important role in this beta cell decline. Therefore, drugs that target ER stress-mediated ? cell dysfunction and death could provide a new therapeutic avenue for diabetes. However, there are currently no approved drugs that directly improve the survival of ? cells. We have utilized a high throughput screening (HTS) approach to successfully identify small molecules that protect ? cell from ER stress-induced death. In this grant, we will focus on one of the potent hits, a natural product Khellin for lead optimization and preclinical studies. Our studies revealed that (a) in cell-based assays, Khellin protects ? cells against ER stress- and glucotoxicity-induced dysfunction and death by modulating the expression of genes involved in ER stress responses, (b) Khellin delays or prevents the onset of hyperglycemia in prediabetic animals and lowers blood glucose in diabetic animals by protecting the function and survival of ? cells, and (c) the ? cell-protective effect of Khellin is mediated by suppression of the expression of thioredoxin-interacting protein (TXNIP), an adaptor protein that connects ER stress, oxidative stress, and inflammation with cell death. Despite its in vivo efficacy, Khellin is poorly soluble in water, has poor oral bioavailability, and is only active at high micromolar concentrations. Therefore, lead optimization will be necessary to identify Khellin analogs with better potency and pharmacological property. In this proposal, our goal is to identify such analogs that lower blood glucose in diabetic animals (phenotypic target) by protecting ? cell function and survival (cellular target) through the modulation of expression of TXNIP involved in ER stress response (pathway target), with improved physicochemical and pharmacokinetic properties, an effort integrating drug targets at the organismal, cellular, and signaling pathway levels, each as specified in this RFA. To achieve these, we plan to 1) synthesize Khelin analogs to improve their biological potency in promoting ? cell survival in cell-based assays and their effect on expression of key ER stress markers, TXNIP in particular; 2) their pharmacological properties, as demonstrated by drug metabolism and pharmacokinetic (DMPK) studies; and 3) their ability to ameliorate hyperglycemia and ? cell protection in animal diabetes models. To develop these first-in-class compounds, we will use an approach that integrates iterative and parallel medicinal chemistry with in vitro and in vivo efficacy and DMPK studies as well as a computational PK and pharmacodynamic (PD) modeling to ensure the most efficient use of time.
The proposed research is directly relevant to public health because our work on chemicals that protect insulin-producing pancreatic beta cell function and survival has the potential to develop them into drugs to diabetes patients. The research can provide valuable insight into the molecular mechanism underlying bet cell dysfunction and death in diabetes.
| Duan, Hongliang; Li, Yu; Arora, Daleep et al. (2017) Discovery of a Benzamide Derivative That Protects Pancreatic ?-Cells against Endoplasmic Reticulum Stress. J Med Chem 60:6191-6204 |
