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Published on: August 11, 2014
Detection of mutagenic activity in human urine using mutant strains of Salmonella typhimurium
Abstract:
Histidine-requiring mutants of Salmonella typhimurium that can be reverted to prototrophy by a variety of mutagens were used mutagenic activity in the urine of patients receiving chemotherapeutic agents. Patients given cyclophosphamide and BCNU had detectable urinary mutagenic activity over a 24-hour period, with maximal levels occurring 12 to 21 hours after drug injection. Whereas native cyclophosphamide required the presence of a rat liver extract to be mutagenic in the test system, the cyclophosphamide metabolites in the urine were fully active in the absence of added liver extract. Mutagenic activity was detected in only the first voided urine specimen of patients receiving fluorouracil. Patients receiving Adriamycin, methotrexate, Mitomycin C, and low doses or oral melphalan did not have detectable mutagenic activity in their urines. One thousand and ten random urine speciments were screened for mutagenic activity. Only eight had greater than 26 revertant colonies per plate. Four of the eight had received metronidazole (Flagyl) for vaginitis while two others had received chemotherapeutic drugs. We were unable to detect increased mutagenic metabolites in the urine of 43 patients with known malignancies, using the standard assay conditions.
Insights
Chemotherapeutic agents like cyclophosphamide and BCNU can cause mutagenic activity in urine. This study detected these urinary mutagens, aiding in understanding drug-induced genotoxicity.
Area of Science:
- Toxicology
- Pharmacology
- Genetics
Background:
- Chemotherapeutic agents are essential for cancer treatment but can pose risks.
- Assessing drug-induced genotoxicity is crucial for patient safety.
- Urinary mutagenicity testing can indicate exposure to harmful metabolites.
Purpose of the Study:
- To investigate the presence and characteristics of mutagenic activity in the urine of patients undergoing chemotherapy.
- To identify specific chemotherapeutic agents associated with urinary mutagenicity.
- To evaluate the potential of urinary mutagenicity as a biomarker for drug exposure.
Main Methods:
- Utilized histidine-requiring Salmonella typhimurium mutants (Ames test) to detect mutagenic activity in patient urine samples.
- Collected urine over 24-hour periods from patients receiving various chemotherapeutic agents.
- Analyzed urine for mutagenic activity with and without rat liver extract to assess the role of metabolic activation.
Main Results:
- Detectable mutagenic activity was found in the urine of patients treated with cyclophosphamide and BCNU, peaking 12-21 hours post-injection.
- Cyclophosphamide metabolites in urine were mutagenic without requiring external liver extract.
- Fluorouracil showed mutagenic activity only in the first urine specimen; Adriamycin, methotrexate, Mitomycin C, and melphalan did not yield detectable activity.
- Screening of random urine samples revealed low background mutagenicity, with a few positive cases linked to metronidazole or chemotherapy.
Conclusions:
- Certain chemotherapeutic agents, notably cyclophosphamide and BCNU, induce mutagenic metabolites excreted in urine.
- Urinary mutagenicity testing can serve as a biomarker for exposure to specific genotoxic chemotherapeutic agents.
- Further research is needed to fully elucidate the clinical significance of these findings and optimize monitoring strategies.
