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Detection of labile anthracycline-DNA adducts by real-time PCR
Damian M S Spencer1, Suzanne M Cutts, Ken-ichi Kimura
1Department of Biochemistry, La Trobe University, Victoria, 3086, Australia.
Abstract:
Barminomycin was employed as a model anthracycline that yields thermally stable drug-DNA adducts. Real-time PCR was utilized for the detection of these barminomycin-DNA adducts at drug levels as low as 100 nM in a cell-free assay system, with the lowest level of detection at approximately 20 nM. By contrast, doxorubicin-DNA adducts are heat labile and their levels were underestimated by conventional real-time PCR unless the DNA denaturation temperature was lowered by the addition of glycerol. Doxorubicin-DNA adduct levels of 5.5 per 10 kb were detected by real-time PCR (in the presence of 24% glycerol) following treatment with 0.5 microM doxorubicin (and 2 mM formaldehyde), considerably more sensitive than that detected by a gene-specific Southern-based procedure. Both the absolute fluorescence intensity in the linear PCR amplification range and the crossing point method provided useful dose-dependent estimates of adduct levels. The time required for a complete real-time PCR analysis of drug-induced adduct levels was approximately 40 min, and this may ultimately provide oncologists with a rapid means with which to monitor drug-DNA adduct levels in patients under treatment with anthracyclines. Responses to these drugs could be quickly and efficiently monitored in patients, thereby facilitating optimization of drug dosages as well as early detection of resistance to these agents.
Insights
Real-time PCR can detect thermally stable barminomycin-DNA adducts and heat-labile doxorubicin-DNA adducts. This method offers rapid monitoring of drug-DNA adducts for optimizing cancer treatment.
Area of Science:
- Pharmacology
- Molecular Biology
- Oncology
Background:
- Anthracyclines are crucial chemotherapeutic agents.
- Accurate monitoring of drug-DNA adducts is vital for effective cancer therapy.
- Existing detection methods for drug-DNA adducts can be time-consuming or lack sensitivity.
Purpose of the Study:
- To develop and validate a rapid real-time PCR method for detecting anthracycline-DNA adducts.
- To compare the detection of thermally stable (barminomycin) and heat-labile (doxorubicin) adducts.
- To assess the potential clinical application of this method for patient monitoring.
Main Methods:
- Utilized real-time PCR for detecting barminomycin-DNA adducts in a cell-free system.
- Optimized real-time PCR by lowering DNA denaturation temperature with glycerol for doxorubicin-DNA adduct detection.
- Compared real-time PCR sensitivity with a gene-specific Southern-based procedure.
Main Results:
- Real-time PCR detected barminomycin-DNA adducts at drug levels as low as 100 nM (detection limit ~20 nM).
- Doxorubicin-DNA adducts were detected at 5.5 adducts/10 kb using real-time PCR with glycerol, surpassing Southern-based methods.
- Both fluorescence intensity and crossing point methods provided dose-dependent adduct level estimates.
- Complete analysis took approximately 40 minutes.
Conclusions:
- Real-time PCR is a sensitive and rapid method for detecting both stable and labile anthracycline-DNA adducts.
- This technique enables efficient monitoring of drug-DNA adduct levels in patients.
- The method facilitates optimization of drug dosages and early detection of resistance to anthracyclines.