PT - JOURNAL ARTICLE AU - Stephanie L. Matheson AU - James McNamee AU - Bertrand J. Jean-Claude TI - Design of a Chimeric 3-Methyl-1,2,3-triazene with Mixed Receptor Tyrosine Kinase and DNA Damaging Properties: A Novel Tumor Targeting Strategy DP - 2001 Mar 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 832--840 VI - 296 IP - 3 4099 - http://jpet.aspetjournals.org/content/296/3/832.short 4100 - http://jpet.aspetjournals.org/content/296/3/832.full SO - J Pharmacol Exp Ther2001 Mar 01; 296 AB - The mixed epidermal growth factor receptor (EGFR)-DNA targeting properties of SMA41, a 6-(3-methyl-1,2,3-triazen-1-yl)-4-anilinoquinazoline designed to release N4-m-tolyl-quinazoline-4,6-diamine henceforth referred to as SMA52 [an inhibitor of EGFR tyrosine kinase (TK)] and methyldiazonium (a DNA methylating species) were studied in the O6-methylguanine-DNA methyltransferase (MGMT)-proficient and high EGFR-expressing epidermoid carcinoma of the vulva cell line A431. The effects of SMA41 were compared with those of SMA52 alone, and temozolomide (TEM), a clinical prodrug of 5-(3-methyltriazen-1-yl)imidazole-4-carboxamide (MTIC) that is inactive in MGMT-proficient cells. The results showed that 1) the chimeric SMA41 could degrade in serum-containing medium (t1/2 of ∼30 min) to generate, as predicted, the free inhibitor SMA52 as the most abundant metabolite (∼81% yield); 2) in contrast to SMA52 alone, the chimeric SMA41 and TEM induced significant DNA damage in A431 cells after 30-min or 2-h drug exposures, as confirmed by alkaline single-cell gel microelectrophoresis (comet) assay; 3) SMA41 showed 5-fold greater affinity for the ATP binding site of EGFR than independently synthesized SMA52 in an enzyme assay and blocked EGF-induced tyrosine phosphorylation and EGFR autophosphorylation in A431 cells in a dose-dependent manner; 4) these mixed targeting properties of SMA41, combined with its ability to be converted to another potent EGFR TK inhibitor (e.g., SMA52) by hydrolytic cleavage, translated into over 8-fold greater antiproliferative activity than TEM, which showed no EGFR targeting properties (IC50 competitive binding >100 μM); 5) under continuous drug exposure (3–6-day sulforhodamine and clonogenic assays), SMA41 was almost equipotent with SMA52; however, in a short 2-h drug exposure followed by incubation in drug-free media, SMA52 showed an almost complete loss of antiproliferative activity over the whole dose range. In contrast, SMA41 retained almost 100% of its activity, indicating a more sustained growth inhibitory activity. The results in toto suggest that the superior antiproliferative activity of SMA41 may be due to a combination of events associated with its binary EGFR TK and DNA targeting properties. The American Society for Pharmacology and Experimental Therapeutics