Related Experiment Videos
The interaction of thymidylate synthase expression with p53-regulated signaling pathways in tumor cells
Daniel B Longley1, Tariq Latif, John Boyer
1Cancer Research Centre, Queen's University Belfast, Belfast, Northern Ireland.
Abstract:
Thymidylate synthase (TS) is a chemotherapeutic target for the fluoropyrimidine 5-fluorouracil (5-FU) and antifolate tomudex (TDX). Using the MCF-7 breast cancer line, we have developed a cell line with inducible TS expression termed M7TS90. Inducible TS expression in this line resulted in a moderate (approximately 3-fold) increase in 5-FU 50% inhibitory concentration at 72 hours (IC-50(72 h)) dose and a dramatic (approximately 24-fold) increase in the IC-50(72 h) dose of TDX, but did not affect chemosensitivity to cisplatin, oxaliplatin, irinotecan, and paclitaxel. In the absence of drug treatment, inducible TS expression had no effect on expression of the p53 tumor suppressor gene. However, TS induction abrogated p53, p21, Fas, and Bak induction in response to TDX, but not 5-FU. Similarly, downregulation of Bcl-2 was reversed by inducible TS expression in TDX, but not 5-FU-treated cells. Our results indicate that inducible TS expression in M7TS90 cells modulates p53 and p53 target gene expression in response to TDX, but not 5-FU.
Insights
Inducible thymidylate synthase (TS) expression increases resistance to tomudex (TDX) chemotherapy by altering p53 pathway responses. This finding is crucial for understanding antifolate drug efficacy in cancer treatment.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Thymidylate synthase (TS) is a key target for 5-fluorouracil (5-FU) and tomudex (TDX) chemotherapy.
- Understanding drug resistance mechanisms is vital for improving cancer therapy outcomes.
Purpose of the Study:
- To investigate the impact of inducible TS expression on chemosensitivity.
- To elucidate the role of TS in mediating resistance to 5-FU and TDX.
Main Methods:
- Development of a breast cancer cell line (MCF-7) with inducible TS expression (M7TS90).
- Assessment of chemosensitivity to various chemotherapeutic agents (5-FU, TDX, cisplatin, oxaliplatin, irinotecan, paclitaxel).
- Analysis of p53 pathway gene expression (p53, p21, Fas, Bak, Bcl-2) in response to drug treatment and TS induction.
Main Results:
- Inducible TS expression caused a moderate increase in 5-FU resistance and a significant increase in TDX resistance.
- TS induction did not affect sensitivity to platinum-based drugs or paclitaxel.
- TS induction abrogated p53, p21, Fas, and Bak induction by TDX, but not 5-FU, and reversed Bcl-2 downregulation by TDX.
Conclusions:
- Inducible TS expression confers resistance to TDX by modulating p53-dependent apoptosis pathways.
- TS-mediated resistance mechanisms differ between 5-FU and TDX.
- These findings highlight the complex role of TS in chemotherapy response and resistance.