Metastatic hibernomas in transgenic mice expressing an alpha-amylase-SV40 T antigen hybrid gene.

Mice transgenic for a hybrid gene containing the liver promoter of the mouse amylase gene (Amy-1a) fused to the SV40 tumor antigen coding region unexpected developed malignant brown adipose tissue tumors (malignant hibernomas). Expression of the alpha-amylase gene had previously been thought to be confined to the liver parotid, and pancreas; however, analysis of white and brown adipose tissue from nontransgenic mice revealed expression of the endogenous Amy-1a gene in these tissues. Gene constructs driven by the Amy-1a liver promoter thus provide a means of targeting gene expression to the adipocyte cell lineage in transgenic mice. Moreover the high frequency of metastases in the liver, lungs, spleen, heart, and adrenals of these mice provides an experimental system in which to study the development of disseminated malignancy.