Cardiac HDAC3 Disruption Contributes to HDAC Inhibitor-Induced QT Prolongation

Area of Science:

• Cardiology
• Molecular Biology
• Pharmacology

Background:

• Histone deacetylase (HDAC) inhibitors show therapeutic potential but can cause cardiac side effects, including QT interval prolongation.
• The precise mechanisms behind HDAC inhibitor-associated cardiotoxicity are not fully understood.

Purpose of the Study:

• To investigate the role of HDAC3 in cardiac electrophysiology.
• To elucidate the molecular mechanisms underlying HDAC inhibitor-induced cardiotoxicity.

Main Methods:

• Investigated the effects of postnatal and adult-onset inducible cardiac-specific HDAC3 depletion in mice.
• Assessed electrocardiogram (EKG) abnormalities and ion channel gene expression.
• Administered HDAC inhibitors (romidepsin, mocetinostat) to mice and evaluated cardiac effects.

Main Results:

• Cardiac HDAC3 depletion in mice led to QT interval prolongation and other EKG abnormalities (T-wave changes).
• Loss of HDAC3 deacetylase activity alone was sufficient to cause QT prolongation.
• HDAC3 disruption and HDAC inhibitor treatment downregulated key potassium channel genes (e.g., Kcnh2, Kcne1, Kcnip2).

Conclusions:

• HDAC3 enzymatic activity is a critical regulator of cardiac repolarization.
• Findings provide mechanistic insights into HDAC inhibitor-associated cardiotoxicity, particularly concerning ion channel function.