Evidence for cyclophosphamide-induced gene conversion and mutation in mouse germ cells

Area of Science:

• Genetics
• Toxicology
• Molecular Biology

Background:

• Cyclophosphamide (CP) is a widely used antineoplastic agent.
• CP is known to be genotoxic, with positive results in various assays like chromosomal aberration tests.
• Its effects on germline genome stability require further investigation.

Purpose of the Study:

• To evaluate the impact of Cyclophosphamide (CP) on the genome stability of mouse spermatogenic cells.
• To assess the utility of the MUSCATEER transgenic assay for detecting CP-induced genotoxicity.
• To determine if CP induces recombination and/or mutation in germline cells.

Main Methods:

• Utilized the MUSCATEER transgenic mouse assay for detecting intrachromosomal gene conversion.
• Administered single intraperitoneal doses of CP (10, 100, 200 mg/kg) to mice.
• Quantified beta-galactosidase activity in spermatids via X-gal staining to measure gene conversion frequency.
• Assessed reversion mutations using a control transgenic line with a frame-shifted lacZ transgene.

Main Results:

• A dose-dependent increase in lacZ-positive spermatids (gene conversion) was observed following CP exposure.
• The highest dose (200 mg/kg) resulted in a 25-fold increase in gene conversion events.
• Evidence suggests CP also induces reversion mutations.
• The timing of the response indicated that recombination and mutation primarily occurred in meiotic stage cells.

Conclusions:

• Cyclophosphamide (CP) exhibits potent germline mutagenicity in mice.
• The MUSCATEER assay is a sensitive and rapid tool for detecting whole-animal genotoxicity.
• CP's effects on genome stability highlight potential risks to reproductive health.