BACKGROUND: Mouse models of metastatic human cancers are important tools in 
preclinical studies for testing new systematic therapies and studying effectors 
of cancer metastasis. The major drawbacks of current mouse models for metastatic 
thyroid cancer are that they have low metastasis rates and do not allow in vivo 
tumor detection. Here, we report and characterize an in vivo detectable 
metastasis mouse model of human thyroid cancer using multiple thyroid cancer 
cell lines.
METHODS: Human anaplastic thyroid cancer cell lines 8505C, C-643, SW-1736, and 
THJ-16T; follicular thyroid cancer cell lines FTC-133, FTC-236, and FTC-238; and 
Hürthle cell carcinoma cell line XTC-1 were transfected with a linearized 
pGL4.51[luc2/CMV/Neo] vector or transduced with lentivirus containing Luc2-eGFP 
reporter genes. The stably transfected cells were injected intravenously into 
NOD.Cg-Prkdc(scid) Il2rg(tm1Wjl)/SzJ mice. Tumors were detected with an in vivo 
imaging system-Xenogen IVIS. Vemurafenib, a BRAF inhibitor, was used to treat 
lung metastases generated from 8505C-Luc2 cells with a BRAF(V600E) mutation to 
test the accuracy of the model to evaluate response to therapy.
RESULTS: Intravenous injection of as few as 30,000 8505C-Luc2 cells produced 
lung metastases in 100% of the injected mice, and many of these mice also 
developed bone metastases at a later stage of the disease. Similarly, metastatic 
tumors also developed in all mice injected with C-643-Luc2, THJ-16T-Luc2, 
FTC-133-Luc2, FTC-236-Luc2, FTC-238-Luc2, and XTC-1-Luc2 cells. The metastases 
were easily detectable in vivo, and tumor progression could be dynamically and 
accurately followed and correlated with the actual tumor burden. Furthermore, 
disease progression could be easily controlled by adjusting the number of 
injected cells. The in vivo treatment of 8505C xenograft lung metastases with 
vemurafenib dramatically reduced the growth and signal intensity with good 
correlation with actual tumor burden.
CONCLUSIONS: Herein we report an in vivo detectable mouse model of metastatic 
human thyroid cancer that is reliable and reproducible. It will serve as a 
useful tool in the preclinical testing of alternative systematic therapies for 
metastatic thyroid cancer, and for functional studies of thyroid cancer tumor 
biology in vivo.