ABSTRACT
Nrf2-mediated activation of ARE regulates expression of cytoprotective enzymes against oxidative stress, inflammation, and carcinogenesis. We have discovered a novel structure (1) as an ARE inducer via luciferase reporter assay to screen the in-house database of our laboratory. The potency of 1 was evaluated by the expression of NQO-1, HO-1, and nuclear translocation of Nrf2 in HCT116 cells. In vivo potency of 1 was studied using AOM-DSS models, showing that the development of colorectal adenomas was significantly inhibited. Administration with 1 lowered the expression of IL-6, IL-1ß, and promoted Nrf2 nuclear translocation. These results indicated that 1 is a potent Nrf2/ARE activator, both in vitro and in vivo. Forty-one derivatives were synthesized for SAR study, and a more potent compound 17 was identified. To our knowledge, this is a potent ARE activator. Besides, its novel structure makes it promising for further optimization.
Subject(s)
Adenoma/prevention & control , Antineoplastic Agents/pharmacology , Antioxidant Response Elements/genetics , Colorectal Neoplasms/prevention & control , NF-E2-Related Factor 2/antagonists & inhibitors , Active Transport, Cell Nucleus/drug effects , Adenoma/chemically induced , Adenoma/pathology , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Azoxymethane , Blotting, Western , Cell Nucleus/drug effects , Cell Nucleus/metabolism , Colorectal Neoplasms/chemically induced , Colorectal Neoplasms/pathology , Dextran Sulfate , Female , Gene Expression Regulation, Neoplastic/drug effects , HCT116 Cells , Heme Oxygenase-1/metabolism , Hep G2 Cells , Heterocyclic Compounds, 3-Ring/chemical synthesis , Heterocyclic Compounds, 3-Ring/chemistry , Heterocyclic Compounds, 3-Ring/pharmacology , Humans , Interleukin-1beta/metabolism , Interleukin-6/metabolism , Mice , Mice, Inbred C57BL , Models, Chemical , Molecular Structure , NAD(P)H Dehydrogenase (Quinone)/metabolism , NF-E2-Related Factor 2/metabolism , Neoplasms/genetics , Neoplasms/metabolism , Neoplasms/pathologyABSTRACT
When exposed to electrophiles, human colorectal cancer cells (HCT116) counteract oxidative stress through activating NF-E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway. To identify new activators, luciferase reporter gene assay was used to screen in-house database of our laboratory, leading to a novel α-pyrone compound 1 as a hit. 2 with 2-fluoro phenyl group exhibited the strongest ARE inductive activity in the first round structure-activity relationship (SAR) study. Biological studies showed the compound induced nuclear translocation of Nrf2 preceded by phosphorylation of ERK1/2. The data encouraged us to use 2 as lead and 20 derivatives were synthesized to discuss a more detailed SAR, leading to a more potent compound 9, which can be the starting compound for further modification.
