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[Pleiotropic resistance associated with topoisomerases]
1Département de biologie, Centre de recherche de Vitry-Alfortville, Vitry-sur-Seine, France.
Bulletin Du Cancer
|December 1, 1994
Summary
Resistance to Topo I and II inhibitors involves altered drug accumulation and reduced complex formation. Multiple mechanisms often combine, leading to pleiotropic resistance in cancer cells.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Topoisomerase (Topo) I and II inhibitors are crucial in cancer therapy.
- Understanding resistance mechanisms is vital for improving treatment efficacy.
Purpose of the Study:
- To elucidate the multifaceted mechanisms of resistance to Topo I and II inhibitors.
- To analyze how combined resistance pathways impact drug effectiveness.
Main Methods:
- Review of established mechanisms of drug resistance.
- Analysis of intracellular drug accumulation pathways (e.g., P-glycoprotein MDR, MRP).
- Examination of alterations in Topo I/II enzyme levels, mutations, isoforms, and phosphorylation.
Main Results:
- Resistance arises from reduced drug accumulation (via MDR or MRP) or impaired cleavable complex formation.
- Reduced complex formation can stem from decreased enzyme levels or mutations.
- Topo II resistance involves isoform expression (alpha/beta) and phosphorylation.
- Dual inhibitors may face complex, combined resistance mechanisms.
Conclusions:
- Pleiotropic resistance, involving multiple mechanisms, is common in cell lines treated with Topo inhibitors.
- Targeting these diverse resistance pathways is essential for overcoming therapeutic challenges.