Journal article
Mechanisms of resistance to N-[5-[ N-(3, 4-dihydro-2-methyl-4-oxoquinazolin-6-ylmethyl)- N-methylamino]-2-thenoyl]-L-glutamic acid (ZD1694), a folate-based thymidylate synthase inhibitor, in the HCT-8 human ileocecal adenocarcinoma cell line
Biochemical pharmacology, Vol.50(3), pp.391-398
1995
DOI: 10.1016/0006-2952(95)00135-M
PMID: 7646540
Abstract
N-[5-[
N-(3,4-Dihydro-2-methyl-4-oxoquinazolin-6-ylmethyl)-
N-methylamino]-2-thenoyl]-L-glutamic acid (ZD1694) is a folate-based thymidylate synthase (TS; EC 2.1.1.45) inhibitor. Metabolism to higher chain length polyglutamates is essential for its optimal cytotoxic effect. A ZD1694-resistant (300-fold) human ileocecal carcinoma cell line (HCT-8/DW2) was developed, and its mechanism of resistance was evaluated. TS activities
in situ and TS protein levels in the HCT-8 parental line and HCT-8/DW2 were similar (168 ± 47 vs 137 ± 25 pmol/hr/10
6 cells and 2.05 ±0.28 vs 2.07 ± 0.19 pmol/mg protein, respectively). The
ic
50 values of ZD1694 for TS inhibition in cell-free extracts were similar in both lines, but the
ic
50 of ZD1694 for TS inhibition
in situ in HCT-8/DW2 cells was 27- and 268-fold higher than that in HCT-8 cells at 0 and 24 hr, respectively, after a 2-hr drug exposure. Folylpolyglutamate synthetase (FPGS; EC 6.3.2.17) activity was significantly lower in resistant HCT-8/DW2 cells as compared with parental HCT-8 cells (88 ± 40 vs 1065 ± 438 pmol/hr/mg protein when ZD1694 was used as substrate). The combined endogenous pool of methylenetetrahydrofolate and tetrahydrofolate in HCT-8/DW2 cells was also decreased. In addition, HCT-8/DW2 cells accumulated lower levels of methotrexate (MTX) in a 2-hr period, although the initial velocity of MTX transport was similar to that in parental HCT-8 cells. The lower level of FPGS activity and the lower level of (anti)folate accumulation in HCT-8/DW2 correlated with drug resistance and with the higher
ic
50 of ZD1694 for
in situ TS inhibition. In addition, drug resistance was also correlated with the rapid recovery of
in situ TS activity after drug treatment. In brief, in this highly ZD1694-resistant HCT-8 cell line, resistance is associated with decreased FPGS activity, which, in turn, affects the metabolism of ZD1694 and consequently the extent and duration of
in situ TS inhibition by the drug.
Details
- Title: Subtitle
- Mechanisms of resistance to N-[5-[ N-(3, 4-dihydro-2-methyl-4-oxoquinazolin-6-ylmethyl)- N-methylamino]-2-thenoyl]-L-glutamic acid (ZD1694), a folate-based thymidylate synthase inhibitor, in the HCT-8 human ileocecal adenocarcinoma cell line
- Creators
- Kun Lu - University of Rome Tor VergataMing-Biao Yin - Roswell Park Cancer InstituteJohn J. McGuire - Roswell Park Cancer InstituteEnzo Bonmassar - University of Rome Tor VergataYoucef M. Rustum - Roswell Park Cancer Institute
- Resource Type
- Journal article
- Publication Details
- Biochemical pharmacology, Vol.50(3), pp.391-398
- Publisher
- Elsevier Inc
- DOI
- 10.1016/0006-2952(95)00135-M
- PMID
- 7646540
- ISSN
- 0006-2952
- eISSN
- 1873-2968
- Language
- English
- Date published
- 1995
- Academic Unit
- Hematology, Oncology, and Blood & Marrow Transplantation; Internal Medicine
- Record Identifier
- 9984359796902771
Metrics
8 Record Views