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Differential methotrexate toxicity between two human oral squamous carcinoma cell lines
1Department of Otolaryngology, University of Western Ontario, Canada.
The Journal of Otolaryngology
|June 1, 1993
Summary
Drug resistance in head and neck cancer is common. This study suggests higher dihydrofolate reductase (DHFR) levels, not drug uptake, likely explain varying methotrexate sensitivity in head and neck squamous cell carcinoma (HNSCC) cells.
Area of Science:
- Oncology
- Pharmacology
- Molecular Biology
Background:
- Methotrexate is a key drug for advanced head and neck squamous cell carcinoma (HNSCC).
- Drug resistance, often due to altered folate transport or increased dihydrofolate reductase (DHFR), limits treatment efficacy.
- Understanding resistance mechanisms is crucial for optimizing HNSCC therapy.
Purpose of the Study:
- To investigate the mechanisms underlying differential sensitivity to methotrexate in HNSCC cell lines.
- To determine if drug uptake or enzyme levels explain variations in methotrexate response.
Main Methods:
- Compared methotrexate sensitivity in two HNSCC cell lines with equal growth rates.
- Measured cellular accumulation of radiolabeled methotrexate.
- Assessed sensitivity to piritrexin, an antifolate entering cells via diffusion.
Main Results:
- A 9-fold difference in methotrexate sensitivity was observed between the cell lines.
- Methotrexate uptake did not differ significantly between the cell lines, suggesting uptake is not the primary resistance factor.
- A 22-fold difference in piritrexin sensitivity indicated that intracellular enzyme levels, likely DHFR, are responsible for differential antifolate sensitivity.
Conclusions:
- Differential sensitivity to antifolates in HNSCC is likely due to quantitative variations in dihydrofolate reductase (DHFR) levels.
- Assessing DHFR content and drug uptake in patient tumors could guide methotrexate treatment decisions.
- This research may lead to more personalized therapeutic strategies for HNSCC.