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Crizotinib Inhibits Hyperpolarization-activated Cyclic Nucleotide-Gated Channel 4 Activity
Zhushan Zhang1, Tai-Qin Huang1, Igor Nepliouev1
1Department of Medicine, Duke University Medical Center, Durham, NC USA 27710.
Background:
Sinus bradycardia is frequently observed in patients treated with crizotinib, a receptor tyrosine kinase inhibitor used for the treatment of anaplastic lymphoma kinase (ALK)-rearranged non-small cell lung cancer (NSCLC). We investigated whether crizotinib could influence heart rate (HR) through direct cardiac effects.
Methods:
The direct effect of crizotinib on HR was studied using ECG analysis of Langendorff-perfused mouse hearts. The whole-cell patch clamp technique was used to measure the effects of crizotinib on the hyperpolarization-activated funny current, If, in mouse sinoatrial node cells (SANCs) and hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) activity in HEK-293 cells stably expressing human HCN4.
Results:
Crizotinib resulted in a dose-dependent reduction in HR in isolated intact mouse hearts with a half maximal inhibitory concentration (IC50) of 1.7 ± 0.4 μmol/L. Because ECG analysis revealed that crizotinib (0-5 μmol/L) resulted in significant reductions in HR in isolated mouse hearts without changes in PR, QRS, or QT intervals, we performed whole-cell patch clamp recordings of SANCs which showed that crizotinib inhibited If which regulates cardiac pacemaker activity. Crizotinib resulted in diminished current density of HCN4, the major molecular determinant of If, with an IC50 of 1.4 ± 0.3 μmol/L. Crizotinib also slowed HCN4 activation and shifted the activation curve to the left towards more hyperpolarized potentials.
Conclusions:
Our results suggest that crizotinib's effects on HCN4 channels play a significant role in mediating its observed effects on HR.
Insights
Crizotinib, used for lung cancer, can slow heart rate by directly affecting cardiac pacemaker cells. This drug inhibits the HCN4 channel, which is crucial for regulating heart rhythm.
Area of Science:
- Cardiology
- Pharmacology
- Oncology
Background:
- Sinus bradycardia is a common side effect in patients treated with crizotinib, an anaplastic lymphoma kinase (ALK) inhibitor for non-small cell lung cancer (NSCLC).
- Investigated potential direct cardiac effects of crizotinib on heart rate (HR).
Purpose of the Study:
- To determine if crizotinib directly influences heart rate through cardiac mechanisms.
- To elucidate the specific ion channel targets responsible for crizotinib-induced bradycardia.
Main Methods:
- Utilized Langendorff-perfused mouse hearts with ECG analysis to assess crizotinib's effect on HR.
- Employed whole-cell patch clamp technique on mouse sinoatrial node cells (SANCs) and HEK-293 cells expressing human HCN4 to study If currents.
Main Results:
- Crizotinib caused a dose-dependent reduction in HR in isolated mouse hearts (IC50 = 1.7 ± 0.4 μmol/L) without altering cardiac conduction intervals (PR, QRS, QT).
- Crizotinib inhibited the hyperpolarization-activated funny current (If) in SANCs, a key regulator of cardiac pacemaking.
- Diminished HCN4 channel activity (IC50 = 1.4 ± 0.3 μmol/L), slowed activation, and shifted the activation curve of HCN4.
Conclusions:
- Crizotinib's inhibition of HCN4 channels is a primary mechanism underlying its bradycardic effects.
- These findings highlight the direct impact of crizotinib on cardiac electrophysiology.
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