Title

Polyphenolic antioxidants mimic the effects of 1,4-dihydropyridines on neurotensin receptor function in PC3 cells

UMMS Affiliation

Department of Physiology

Publication Date

1-14-2004

Document Type

Article

Subjects

Antioxidants; Calcium; Calcium Channel Agonists; Calcium Channel Blockers; Calcium Channels; Dihydropyridines; Electron-Transferring Flavoproteins; Flavonoids; Humans; Male; Oxidation-Reduction; Oxidoreductases; Phenols; Potassium; Receptors, Neurotensin; Sodium; Sulfhydryl Compounds; Tumor Cells, Cultured

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

This study aimed to determine the mechanism(s) by which 1,4-dihydropyridine Ca2+ channel blockers (DHPs) enhance the binding of neurotensin (NT) to prostate cancer PC3 cells and inhibit NT-induced inositol phosphate formation. Earlier work indicated that these effects, which involved the G protein-coupled NT receptor NTR1, were indirect and required cellular metabolism or architecture. At the micromolar concentrations used, DHPs can block voltage-sensitive and store-operated Ca2+ channels, K+ channels, and Na+ channels, and can inhibit lipid peroxidation. By varying [Ca2+] and testing the effects of stimulators and inhibitors of Ca2+ influx and internal Ca2+ release, we determined that although DHPs may have inhibited inositol phosphate formation partly by blocking Ca2+ influx, the effect on NT binding was Ca2+-independent. By varying [K+] and [Na+], we showed that these ions did not contribute to either effect. For a series of DHPs, the activity order for effects on NTR1 function followed that for antioxidant ability. Antioxidant polyphenols (luteolin and resveratrol) mimicked the effects of DHPs and showed structural similarity to DHPs. Antioxidants with equal redox ability, but without structural similarity to DHPs (such as alpha-tocopherol, riboflavin, and N-acetyl-cysteine) were without effect. A flavoprotein oxidase inhibitor (diphenylene iodonium) and a hydroxy radical scavenger (butylated hydroxy anisole) also displayed the effects of DHPs. In conclusion, DHPs indirectly alter NTR1 function in live cells by a mechanism that depends on the drug's ability to donate hydrogen but does not simply involve sulfhydryl reduction.

Rights and Permissions

Citation: J Pharmacol Exp Ther. 2004 Apr;309(1):92-101. Epub 2004 Jan 12. Link to article on publisher's site

DOI of Published Version

10.1124/jpet.103.060442

Related Resources

Link to Article in PubMed

Journal/Book/Conference Title

The Journal of pharmacology and experimental therapeutics

PubMed ID

14718582