Abstract
The Combi-Targeting concept postulates that a molecule termed combi-molecule (C-molecule) with binary epidermal growth factor receptor (EGFR) targeting/DNA-damaging properties and with the ability to be hydrolyzed to another EGFR inhibitor should induce sustained antiproliferative activity in cells overexpressing EGFR. Because we postulate that the EGFR affinity of the C-molecule and that of its hydrolytic metabolites are critical parameters for sustained potency against EGFR-overexpressing cells, we synthesized BJ2000 (IC50 = 0.1 μM, competitive binding at ATP site), a novel C-molecule that can decompose into a 6-amino-4-anilinoquinazoline FD105 (IC50 = 0.2 μM). Studies using the EGFR-overexpressing A431 cells revealed that BJ2000 could damage DNA and block epidermal growth factor-stimulated EGFR autophosphorylation by a partially irreversible mechanism. Blockade of EGFR autophosphorylation subsequently induced inhibition of mitogen-activated protein kinase activation and c-fos gene expression. Enzyme-linked immunosorbent assay and growth factor-mediated stimulation of proliferation assays in the EGFR-expressing NIH3T3HER14 demonstrated the preferential EGFR-targeting properties of BJ2000, and more importantly suggest that blockade of EGFR phosphorylation by this drug translate into significant growth inhibitory effects. These properties culminated into irreversible antiproliferative effects as confirmed by a sulforhodamine B assay. Five days after a 2-h treatment, BJ2000 retained significant antiproliferative effect in A431 cells, whereas its reversible metabolite FD105 almost completely lost its activity. This result in toto lend support to the Combi-Targeting concept according to which a molecular conjugate kept small enough to interact with EGFR and designed to degrade into another inhibitor of the same target plus a DNA-damaging species may induce sustained growth inhibitory effect in EGFR-overexpressing cells.
Footnotes
-
This study was supported by Cancer Research Society Inc. (to C.R.S.). This work was presented as an abstract at the AACR-NCI-EORTC Molecular Targets and Cancer Therapeutics Meeting. Proc. of 2001 AACR-NCI-EORTC Please spell out AACR-NCI-EORTC in funding footnote. International Conference, Abstract 594, p 121.
-
DOI: 10.1124/jpet.102.039099
- Abbreviations:
- EGFR
- epidermal growth factor receptor
- TK
- tyrosine kinase
- EGF
- epidermal growth factor
- C-molecule
- combi-molecule
- TEM
- temozolomide
- MTIC
- monoalkyltriazene 5-(3-methyltriazen-1-yl)imidazole-4-carboxamide
- DMSO
- dimethyl sulfoxide
- FBS
- fetal bovine serum
- HPLC
- high-pressure liquid chromatography
- PGT
- poly(l-glutamic acid-l-tyrosine, 4:1)
- PBS
- phosphate-buffered saline
- ELISA
- enzyme-linked immunosorbent assay
- PDGF
- platelet-derived growth factor
- MAPK
- mitogen-activated protein kinase
- Erk2
- extracellular signal-regulated kinase 2
- RT-PCR
- reverse transcription-polymerase chain reaction
- TGFα
- transforming growth factor-α
- SRB
- sulforhodamine B
- AGT
- O6-alkylguanine DNA transferase
- GAPDH
- glyceraldehyde-3-phosphate dehydrogenase
- Received May 15, 2002.
- Accepted June 12, 2002.
- The American Society for Pharmacology and Experimental Therapeutics
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|