AG18 is an inhibitor of EGFR kinase with IC50 values of 35μM. [3]
AG18 acts as general tyrosine kinase inhibitor to block tyrosine phosphorylation and events downstream of tyrosine phosphorylation. [1]
AG18 and AG10 reduced cellular ATP by 90% and increased the rate of oxygen consumption in the absence of the muscarinic agonist carbachol, indicating that these tyrphostins uncouple mitochondria. AG18 and AG10 blocked parotid phosphorylation events only at concentrations that reduced ATP content. AG18 and AG10 also activated AMPK and/or uncoupled mitochondria inHEK293, PC12, and HeLa cells. [1]
In granulosa-lutein cells, tyrphostin AG18 reversiblely arrested the FSH-induced accumulation of P450scc mRNA with IC50 value of 15 mu M. However, AG18 did not accelerate the mRNA degradation process. Moreover, even the extremely high levels of P450scc mRNA in granulosa-lutein cells, were not affected by the addition of AG18 in culture. Aromatase cytochrome P450 and 3 beta-hydroxysteroid dehydrogenase-I, were inhibited by AG18 at their mRNA levels. [2]
References:
[1]. Soltoff SP. Evidence that tyrphostins AG10 and AG18 are mitochondrial uncouplers that alter phosphorylation-dependent cell signaling. J Biol Chem. 2004 Mar 19;279(12):10910-8. Epub 2003 Dec 19.
[2]. Orly J, Rei Z, Greenberg NM et al. Tyrosine kinase inhibitor AG18 arrests follicle-stimulating hormone-induced granulosa cell differentiation: use of reverse transcriptase-polymerase chain reaction assay for multiple messenger ribonucleic acids. Endocrinology. 1994 Jun;134(6):2336-46.
[3]. Gazit A, Yaish P, Gilon C et al. Tyrphostins I: synthesis and biological activity of protein tyrosine kinase inhibitors. J Med Chem. 1989 Oct;32(10):2344-52.