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Assays for Validating Histone Acetyltransferase Inhibitors
Published on: August 6, 2020
Repurposing acetyldigitoxin as a potential EZH2 inhibitor for non-small cell lung cancer: a computational and
Xiang Ji1, Xiyan Wang1, Ting Xiu2
1Respiratory Department, First Affiliated Hospital of Shandong First Medical University, No. 16766, Jingshi Road, Qianfoshan Street, Lixia District, Jinan City, 250014, Shandong Province, China.
Abstract:
Non-small cell lung cancer (NSCLC) remains a leading cause of cancer-related mortality worldwide. The epigenetic regulator EZH2 is a promising therapeutic target due to its role in tumor progression and therapy resistance. This study combined computational and experimental methods to repurpose FDA-approved drugs as EZH2 inhibitors. Virtual screening and molecular dynamics simulations identified acetyldigitoxin (ADT) as a potent EZH2 inhibitor, demonstrating superior binding affinity (-10.90 kcal/mol) and complex stability compared to the known inhibitor GSK126. ADT formed robust hydrogen bonds and hydrophobic interactions with key residues in the EZH2 binding site, supported by favorable binding free energy calculations (ΔGbinding = -34.73 kcal/mol). In vitro, ADT exhibited selective cytotoxicity against NSCLC A549 cells (IC₅₀ = 32.4 nM) versus normal bronchial epithelial cells (IC₅₀ = 190 nM). Treatment with ADT significantly reduced EZH2 expression and potently inhibited its histone methyltransferase activity, as directly evidenced by decreased global H3K27me3 levels. ADT induced G0/G1 cell cycle arrest and promoted apoptosis, accompanied by upregulation of pro-apoptotic genes (Bax, Caspase-3) and downregulation of anti-apoptotic (Bcl-2) and cell cycle (CyclinD1) genes. Our integrated findings position ADT as a repurposed drug candidate for targeting EZH2 in NSCLC, warranting further preclinical investigation including direct enzyme inhibition assays.
Insights
Acetyldigitoxin (ADT) is identified as a potent inhibitor of EZH2, an epigenetic regulator crucial in non-small cell lung cancer (NSCLC). This repurposed drug shows selective toxicity against NSCLC cells, offering a new therapeutic avenue.
Area of Science:
- Oncology
- Epigenetics
- Pharmacology
Background:
- Non-small cell lung cancer (NSCLC) is a major global health concern.
- Enhancer of Zeste Homolog 2 (EZH2) is an epigenetic regulator implicated in NSCLC progression and treatment resistance.
- Targeting EZH2 presents a promising strategy for NSCLC therapy.
Purpose of the Study:
- To repurpose FDA-approved drugs as inhibitors of EZH2 for NSCLC treatment.
- To identify novel EZH2 inhibitors through computational and experimental approaches.
Main Methods:
- Virtual screening and molecular dynamics simulations were employed to identify potential EZH2 inhibitors.
- In vitro assays were conducted to assess the cytotoxicity and molecular effects of the identified compound.
- Key molecular interactions and binding affinities were computationally evaluated.
Main Results:
- Acetyldigitoxin (ADT) was identified as a potent EZH2 inhibitor with superior binding affinity and stability compared to GSK126.
- ADT demonstrated selective cytotoxicity against NSCLC A549 cells.
- ADT treatment reduced EZH2 expression, inhibited its methyltransferase activity (decreased H3K27me3), induced G0/G1 cell cycle arrest, and promoted apoptosis in NSCLC cells.
Conclusions:
- Acetyldigitoxin (ADT) is a promising repurposed drug candidate for targeting EZH2 in NSCLC.
- ADT exhibits potent anti-cancer effects through EZH2 inhibition, cell cycle arrest, and apoptosis induction.
- Further preclinical studies are warranted to validate ADT as an NSCLC therapeutic agent.
