PET/CT imaging of c-Myc transgenic mice identifies the genotoxic N-nitroso-diethylamine as carcinogen in a short-term cancer bioassay.
BACKGROUND
More than 100,000 chemicals are in use but have not been tested for their safety. To overcome limitations in the cancer bioassay several alternative testing strategies are explored. The inability to monitor non-invasively onset and progression of disease limits, however, the value of current testing strategies. Here, we report the application of in vivo imaging to a c-Myc transgenic mouse model of liver cancer for the development of a short-term cancer bioassay.


RESULTS
μCT and ¹⁸F-FDG μPET were used to detect and quantify tumor lesions after treatment with the genotoxic carcinogen NDEA, the tumor promoting agent BHT or the hepatotoxin paracetamol. Tumor growth was investigated between the ages of 4 to 8.5 months and contrast-enhanced μCT imaging detected liver lesions as well as metastatic spread with high sensitivity and accuracy as confirmed by histopathology. Significant differences in the onset of tumor growth, tumor load and glucose metabolism were observed when the NDEA treatment group was compared with any of the other treatment groups. NDEA treatment of c-Myc transgenic mice significantly accelerated tumor growth and caused metastatic spread of HCC in to lung but this treatment also induced primary lung cancer growth. In contrast, BHT and paracetamol did not promote hepatocarcinogenesis.


CONCLUSIONS
The present study evidences the accuracy of in vivo imaging in defining tumor growth, tumor load, lesion number and metastatic spread. Consequently, the application of in vivo imaging techniques to transgenic animal models may possibly enable short-term cancer bioassays to significantly improve hazard identification and follow-up examinations of different organs by non-invasive methods.
Institute for Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany.
Katja
K
Hueper
Mahmoud
M
Elalfy
Florian
F
Laenger
Roman
R
Halter
Thomas
T
Rodt
Michael
M
Galanski
Juergen
J
Borlak
D000818:Animals; D002273:Carcinogens / Q000633:toxicity; D049109:Cell Proliferation; D003952:Diagnostic Imaging / Q000379:methods / Q000592:standards; D004052:Diethylnitrosamine / Q000633:toxicity*; D005947:Glucose / Q000378:metabolism; D008113:Liver Neoplasms / Q000139:chemically induced / Q000175:diagnosis* / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D064847:Multimodal Imaging; D009362:Neoplasm Metastasis; D049268:Positron-Emission Tomography; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics*; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
D002273:Carcinogens; C489428:Myc protein, mouse; D016271:Proto-Oncogene Proteins c-myc; D004052:Diethylnitrosamine; D005947:Glucose