This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Longley, D. B. Articles by Johnston, P. G. Search for Related Content PubMed PubMed Citation Articles by Longley, D. B. Articles by Johnston, P. G.

The Role of Thymidylate Synthase Induction in Modulating p53-regulated Gene Expression in Response to 5-Fluorouracil and Antifolates¹

Department of Oncology, Cancer Research Centre, Queen’s University Belfast, Belfast BT9 7AB, Northern Ireland

Thymidylate synthase (TS) is a critical target for chemotherapeutic agentssuch as 5-fluorouracil (5-FU) and antifolates such as tomudex (TDX),multitargeted antifolate, and ZD9331. Using the MCF-7 breast cancer line, we have developed p53 wild-type (M7TS90) and null (M7TS90-E6) isogenic lines with inducible TS expression (6-fold induction compared with control after 48 h). In the M7TS90 line, inducible TS expression resulted in a moderate 3-fold increase in 5-FU IC-50^72h dose and a dramatic >20-fold increase in the IC-50^72h doses of TDX, multitargeted antifolate, and ZD9331. S-phase cell cycle arrest and apoptosis induced by the antifolates were abrogated by TS induction. In contrast, cell cycle arrest and apoptosis induced by 5-FU was unaffected by TS expression levels. Inactivation of p53 significantly increased resistance to 5-FU and the antifolates with IC-50^72h doses for 5-FU and TDX of >100 and >10 µM, respectively, in the M7TS90-E6 cell line. Furthermore, p53 inactivation completely abrogated the cell cycle arrest and apoptosis induced by 5-FU. The antifolates induced S-phase arrest in the p53 null cell line; however, the induction of apoptosis by these agents was significantly reduced compared with p53 wild-type cells. Both inducible TS expression and the addition of exogenous thymidine (10 µM) blocked p53 and p21 induction by the antifolates but not by 5-FU in the M7TS90 cell line. Similarly, inducible TS expression and exogenous thymidine abrogated antifolate but not 5-FU-mediated up-regulation of Fas/CD95 in M7TS90 cells. Our results indicate that in M7TS90 cells, inducible TS expression modulates p53 and p53 target gene expression in response to TS-targeted antifolate therapies but not to 5-FU.

This article has been cited by other articles:

				C.-M. Hu and Z.-F. Chang Synthetic Lethality by Lentiviral Short Hairpin RNA Silencing of Thymidylate Kinase and Doxorubicin in Colon Cancer Cells Regardless of the p53 Status Cancer Res., April 15, 2008; 68(8): 2831 - 2840. [Abstract] [Full Text] [PDF]

				T. R. Wilson, K. M. McLaughlin, M. McEwan, H. Sakai, K. M.A. Rogers, K. M. Redmond, P. G. Johnston, and D. B. Longley c-FLIP: A Key Regulator of Colorectal Cancer Cell Death Cancer Res., June 15, 2007; 67(12): 5754 - 5762. [Abstract] [Full Text] [PDF]

				X.-X. Sun, M.-S. Dai, and H. Lu 5-Fluorouracil Activation of p53 Involves an MDM2-Ribosomal Protein Interaction J. Biol. Chem., March 16, 2007; 282(11): 8052 - 8059. [Abstract] [Full Text] [PDF]

				W. L. Allen, E. G. McLean, J. Boyer, A. McCulla, P. M. Wilson, V. Coyle, D. B. Longley, R. A. Casero Jr., and P. G. Johnston The role of spermidine/spermine N1-acetyltransferase in determining response to chemotherapeutic agents in colorectal cancer cells Mol. Cancer Ther., January 1, 2007; 6(1): 128 - 137. [Abstract] [Full Text] [PDF]

				S Popat, Z Chen, D Zhao, H Pan, N Hearle, I Chandler, Y Shao, W Aherne, and R. Houlston A prospective, blinded analysis of thymidylate synthase and p53 expression as prognostic markers in the adjuvant treatment of colorectal cancer Ann. Onc., December 1, 2006; 17(12): 1810 - 1817. [Abstract] [Full Text] [PDF]

				J. L. Westra, H. Hollema, M. Schaapveld, I. Platteel, K. A. Oien, W. N. Keith, R. Mauritz, G. J. Peters, C. H. C. M. Buys, R. M. W. Hofstra, et al. Predictive value of thymidylate synthase and dihydropyrimidine dehydrogenase protein expression on survival in adjuvantly treated stage III colon cancer patients Ann. Onc., October 1, 2005; 16(10): 1646 - 1653. [Abstract] [Full Text] [PDF]

				D. B. Longley, W. L. Allen, U. McDermott, T. R. Wilson, T. Latif, J. Boyer, M. Lynch, and P. G. Johnston The Roles of Thymidylate Synthase and p53 in Regulating Fas-Mediated Apoptosis in Response to Antimetabolites Clin. Cancer Res., May 15, 2004; 10(10): 3562 - 3571. [Abstract] [Full Text] [PDF]

				J. Boyer, E. G. McLean, S. Aroori, P. Wilson, A. McCulla, P. D. Carey, D. B. Longley, and P. G. Johnston Characterization of p53 Wild-Type and Null Isogenic Colorectal Cancer Cell Lines Resistant to 5-Fluorouracil, Oxaliplatin, and Irinotecan Clin. Cancer Res., March 15, 2004; 10(6): 2158 - 2167. [Abstract] [Full Text] [PDF]

				K.-H. Chi, H.-E. Wang, Y.-S. Wang, S.-L. Chou, H.-M. Yu, Y.-H. Tseng, I.-M. Hwang, and W.-Y. Lui Antisense Thymidylate Synthase Electrogene Transfer to Increase Uptake of Radiolabeled Iododeoxyuridine in a Murine Model J. Nucl. Med., March 1, 2004; 45(3): 478 - 484. [Abstract] [Full Text]

				R. Simstein, M. Burow, A. Parker, C. Weldon, and B. Beckman Apoptosis, Chemoresistance, and Breast Cancer: Insights From the MCF-7 Cell Model System Experimental Biology and Medicine, October 1, 2003; 228(9): 995 - 1003. [Abstract] [Full Text] [PDF]

				P. J. Maxwell, D. B. Longley, T. Latif, J. Boyer, W. Allen, M. Lynch, U. McDermott, D. P. Harkin, C. J. Allegra, and P. G. Johnston Identification of 5-fluorouracil-inducible Target Genes Using cDNA Microarray Profiling Cancer Res., August 1, 2003; 63(15): 4602 - 4606. [Abstract] [Full Text] [PDF]

				J. Ciccolini, F. Fina, K. Bezulier, S. Giacometti, M. Roussel, A. Evrard, P. Cuq, S. Romain, P.-M. Martin, and C. Aubert Transmission of Apoptosis in Human Colorectal Tumor Cells Exposed to Capecitabine, Xeloda, Is Mediated via Fas Mol. Cancer Ther., September 1, 2002; 1(11): 923 - 927. [Abstract] [Full Text] [PDF]