Endogenously generated nitric oxide by nitric-oxide synthase gene transfer inhibits cellular proliferation

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• Cellular proliferation is a fundamental biological process.
• Endothelial nitric oxide synthase (NOS) plays a role in various cellular functions.
• Endothelin-1 is known to stimulate cellular proliferation.

Purpose of the Study:

• To investigate the effect of endothelial NOS gene transfer on cellular proliferation.
• To determine the molecular mechanisms underlying the inhibition of proliferation by endothelial NOS gene transfer.

Main Methods:

• Gene transfer of endothelial NOS and endothelin type A receptor into 293 cells using calcium-phosphate coprecipitation.
• Measurement of cytosolic free Ca(2+) levels using fura-2 fluorescence.
• Assay of thymidine incorporation to assess cellular proliferation.
• Analysis of mitogen-activated protein kinase and c-fos promoter activities.
• Inhibition studies using N(G)-monomethyl-L-arginine acetate and PD98059.

Main Results:

• Endothelin-1 increased thymidine incorporation in type A receptor-transfected cells.
• Endothelial NOS gene transfer inhibited endothelin-1-induced thymidine incorporation and cell number increase.
• Endothelial NOS gene transfer suppressed mitogen-activated protein kinase and c-fos promoter activities.
• The inhibitory effect of endothelial NOS gene transfer was abolished by a NOS inhibitor and a mitogen-activated protein kinase inhibitor.

Conclusions:

• Endothelial NOS gene transfer effectively inhibits cellular proliferation.
• The mechanism involves the downregulation of the mitogen-activated protein kinase cascade.
• This suggests a potential therapeutic role for endothelial NOS gene transfer in controlling cell growth.