title: Design of a chimeric 3-methyl-1,2,3-triazene with mixed receptor tyrosine kinase and DNA damaging properties: a novel tumor targeting strategy.
abstract: 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 N(4)-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 O(6)-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 (t(1/2) of approximately 30 min) to generate, as predicted, the free inhibitor SMA52 as the most abundant metabolite (approximately 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 (IC(50) competitive binding >100 microM); 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.
authors.affiliation: Cancer Drug Research Laboratory, Department of Medicine, Division of Medical Oncology, McGill University Health Centre/Royal Victoria Hospital, Montreal, Quebec, Canada.
authors.forename: S L
authors.initials: SL
authors.lastname: Matheson
authors.forename: J
authors.initials: J
authors.lastname: McNamee
authors.forename: B J
authors.initials: BJ
authors.lastname: Jean-Claude
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D004247:DNA / Q000187:drug effects* / Q000378:metabolism; D004249:DNA Damage; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors; D006801:Humans; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011799:Quinazolines / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D000077204:Temozolomide; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D011799:Quinazolines; C421705:SMA-41; C421706:SMA-52; D003606:Dacarbazine; D004247:DNA; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D000077204:Temozolomide