- Title
- Small molecule screening to discover the ligands of glucose regulated protein 78 and aldehyde oxidase 1 inhibitors for the respective treatment of cancer and oxidative stress-induced pregnancy complications
- Creator
- Qiao, Yixue
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2021
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Previously drugs were discovered either by serendipty or by identifying the active components from traditional medicines. Small molecule screening has recently become a common method for identifying compounds that produce therapeutically desirable functions, which can be further modified as drug candidates. This thesis describes two studies on small-molecule screening for the discovery of bioactive small molecules targeting the Glucose Regulated Protein 78 kDa (GRP78) and Aldehyde Oxidase 1 (AOX1) for the treatment of cancer and oxidative stress-induced pregnancy complications respectively. Glucose Regulated Protein 78 kDa (GRP78) is an attractive antiangiogenic and anticancer target for its selective accumulation on the surface of cancer cells and cancer endothelial cells rather than normal cells. In this study, we identified a novel series of small molecules that binds to GRP78, exhibiting potent antiangiogenic and anticancer activities without affecting normal cells. Among these, FL5, 2-(4-((4-acetamidophenoxy)methyl)phenyl)-N-isobutylbenzofuran-3-carboxamide, was superior to others due to its strong binding affinity to GRP78 (an increase in the Tm > 2 ℃ stabilising the GRP78 protein) and potent antiangiogenic and anticancer activities against human umbilical vein endothelial cells (HUVEC) (EC50 = 1.514 µM) and human renal cancer cells (786-O) (50% cell death at 10 µM). Furthermore, FL5 displayed no cytotoxic activity towards normal cells (mouse fibroblast cells, Swiss-3T3), which do not harbour cell surface GRP78 under normal condition. FL5 was less detrimental to ATPase activity, which is essential for normal cells, as seen in the virtual docking studies. This study reports the discovery of novel small molecules targeting GRP78 with potent antiangiogenic and anticancer activities and less toxicity to normal cells, which provides prototype candidates for novel paths for cancer therapy. AOX1 plays a role in oxidative stress (OS) in the human placenta, which is a contributing factor in the pathophysiology of many adverse pregnancy outcomes including pre-eclampsia, intrauterine growth restriction, antepartum fetal death and gestational diabetes. The AOX1 inhibitor, raloxifene, can block oxidative damage in placental cells and explants. In this study, we sought to develop novel, potent and druggable inhibitors of AOX1, with a view to arresting the oxidative damage in the placenta that is associated with adverse obstetric outcomes. The in vitro activity assay is efficient and selective for AOX1. The compounds YX5, YX14, YX15 and YX16 (IC50 = 12.13-39.92 nM) are stronger AOX1 inhibitors than raloxifene (IC50 = 86.09 nM). We identified YX14 and YX15 as the strongest AOX1 inhibitors yet described. YX14 and YX15 was able to block oxidative damage to the DNA/RNA in the placental explant. These inhibitors produced no effects on placental HTR-8/SV neo cell growth. Modelling suggests that the identified compounds interact with the same binding pocket in AOX1 as raloxifene, and YX14 and YX15 are involved in 1 or 2 more hydrogen bonds than the others, explaining their robust inhibitory activity. We have successfully identified two potent and nontoxic AOX1 inhibitors, which are promising drug candidates for the treatment of OS-induced pregnancy complications. This thesis has successfully identified two series of bioactive compounds that target two physiologically and pathologically functional proteins. These compounds are promising drug candidates, and our modelling will guide the development of even better compounds.
- Subject
- drug discovery; GRP78 ligand; AOX1 inhibitor; cancer; pregnancy complications
- Identifier
- http://hdl.handle.net/1959.13/1514291
- Identifier
- uon:56845
- Rights
- Copyright 2021 Yixue Qiao
- Language
- eng
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