A quantitative RT-PCR method to determine topoisomerase I mRNA levels in human tissue samples.

DNA topoisomerase I (Topo I) is involved in DNA replication, transcription, recombination and repair. Clinical interest has focused on Topo I as it is the molecular target of camptothecin (CPT), used in first and second lines of treatment for different cancer types. Furthermore, it is well demonstrated that the patients who best responded to CPT-based chemotherapy were generally those with the greatest tumoral Topo I expression and/or activity.