The calcium channel blocker cilnidipine selectively suppresses hypoxia-inducible factor 1 activity in vascular cells

Area of Science:

• Cellular signaling and molecular biology
• Hypoxia research
• Calcium channel pharmacology

Background:

• Calcium ions act as crucial second messengers in cellular signal transduction, particularly in response to hypoxia.
• Hypoxia-inducible factor-1 (HIF-1) is a key transcription factor regulating gene expression during hypoxic conditions.

Purpose of the Study:

• To investigate the effects of L-type calcium channel blockers on hypoxia-inducible factor-1 (HIF-1) activity.
• To determine the specific mechanisms by which cilnidipine affects HIF-1 activity and its downstream gene expression.

Main Methods:

• Utilized lung carcinoma (A549), human aortic smooth muscle, and human umbilical vein endothelial cells.
• Examined the impact of various L-type calcium channel blockers (nifedipine, efonidipine, cilnidipine, diltiazem, verapamil) on HIF-1 activity.
• Investigated the effects on HIF-1alpha protein synthesis, prolyl hydroxylase activity, Akt, and mitogen-activated protein kinase (MAPK) pathways.

Main Results:

• Cilnidipine selectively suppressed HIF-1 activity and downstream gene expression in a cell-type specific manner.
• Cilnidipine inhibited HIF-1alpha protein synthesis by targeting Akt and MAPK pathways.
• The observed inhibition by cilnidipine was independent of its effects on calcium homeostasis and did not involve prolyl hydroxylase activity.

Conclusions:

• Cilnidipine exhibits unique cell-type specific inhibitory effects on HIF-1 signaling.
• The mechanism of cilnidipine's action involves the Akt and MAPK pathways, not direct modulation of calcium homeostasis or prolyl hydroxylases.
• These findings highlight cilnidipine as a potential modulator of hypoxia-induced gene expression in specific cellular contexts.