Carcinogenic comparative study on rasH2 mice produced by two breeding facilities

Area of Science:

• Toxicology
• Genetics
• Oncology

Background:

• The rasH2 mouse (CByB6F1-Tg(HRAS)2Jic) is a transgenic model used in carcinogenicity studies.
• This model is supplied globally by two primary breeding facilities: CLEA Japan and Taconic.
• Ensuring consistency in carcinogenic response between mice from different suppliers is crucial for reliable study outcomes.

Purpose of the Study:

• To confirm the carcinogenic conformity of rasH2 mice obtained from CLEA Japan and Taconic.
• To validate that both sources of rasH2 mice exhibit comparable responses in carcinogenicity testing under identical conditions.

Main Methods:

• A 26-week carcinogenicity test was conducted on 120 rasH2 mice from both breeding facilities.
• Mice were administered either a vehicle control (citrate buffer) or N-methyl-N-nitrosourea (MNU).
• Tumor incidence, survival rates, and pathological examinations were analyzed.

Main Results:

• All mice in the vehicle group survived, with only benign tumors observed.
• MNU administration resulted in a 100% incidence of forestomach tumors and high rates of malignant lymphoma in both groups.
• No significant differences in tumor incidence or type were found between mice from CLEA Japan and Taconic.

Conclusions:

• The study confirms the carcinogenic conformity of rasH2 mice from CLEA Japan and Taconic.
• rasH2 mice from both suppliers demonstrate consistent and comparable responses to MNU-induced carcinogenicity.
• This validated conformity supports the use of rasH2 mice from either facility in global carcinogenicity assessments.