Journal article
DNA damage and p53 induction do not cause ZD1694-induced cell cycle arrest in human colon carcinoma cells
Cancer research (Chicago, Ill.), Vol.56(20), pp.4715-4723
10/15/1996
PMID: 8840989
Abstract
Using four complementary approaches, ie., cell synchronization, bromodeoxyuridine labeling, and DNA and Western blot analyses, we investigated the underlying mechanism of cell cycle perturbation in response to ZD1694, a quinazoline-based antifolate thymidylate synthase inhibitor. With a single exposure at a concentration of 1 microM for 2 h, ZD1694 completely inhibits thymidylate synthase over 72 h and causes a sustained growth for at least 120 h, DNA damage, and p53 induction in human carcinoma cells. Although these cells displayed an S-phase block with the precise terminal arrest point depending on the timing of drug treatment in the cell cycle, their DNA-replicating machinery associated with polymerase alpha was preserved intact. When supplemented with exogenous dThd, these cells resumed an apparently normal S-phase progression for at least 4 h. Kinetic analyses based on synchronized cells indicate that S-phase arrest occurs first, preceding the induction of DNA double strand breaks and p53/p21. SW480 cells, in which p53mu failed to transduce p21, also exhibited the mode of S-phase arrest, essentially indistinguishable from that displayed by HCT-8 cells expressing the functional p53 (p53wt). That the DNA replication process is prerequisite for DNA double strand breaks was indicated by the following: (a) DNA damage occurred only when cells treated with ZD1694 progressed through S phase; and (b) the inhibition of DNA polymerase alpha by aphidicolin-blocked DNA damage. Based on the above, we conclude that S-phase arrest by ZD1694, with a subsequent damage of DNA double strands, is caused by the block of DNA synthesis in the middle of replication due to dTTP depletion and not by p53-mediated G1-G2 checkpoint mechanisms or p21-induced inactivation of the DNA-replicating machinery.
Details
- Title: Subtitle
- DNA damage and p53 induction do not cause ZD1694-induced cell cycle arrest in human colon carcinoma cells
- Creators
- S I Matsui - Roswell Park Cancer InstituteM A ArredondoC WrzosekY M Rustum
- Resource Type
- Journal article
- Publication Details
- Cancer research (Chicago, Ill.), Vol.56(20), pp.4715-4723
- PMID
- 8840989
- ISSN
- 0008-5472
- eISSN
- 1538-7445
- Grant note
- CA09581 / NCI NIH HHS R01 CA65761 / NCI NIH HHS CA16056 / NCI NIH HHS
- Language
- English
- Date published
- 10/15/1996
- Academic Unit
- Hematology, Oncology, and Blood & Marrow Transplantation; Internal Medicine
- Record Identifier
- 9984360055702771
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