Breast cancer is a common malignant tumor. It is essential to develop suitable animal models for
discovering novel preventive and therapeutic approaches. Tree shrews (
Tupaia belangeri chinenesis
) have a closer
evolutionary relationship with humans than do rodents, which have been widely used in laboratory research. Spontaneous
breast tumors were identified in tree shrews in 1960s; however, no detailed studies about tree shrew breast tumors have
been conducted to date. Here, we characterized a spontaneous breast tumor from tree shrews by Haematoxylin Eosin
(H&E) staining. This tumor was identified as a papillary tumor. Immunohistochemical staining (IHC) for progesterone
receptor (PR), Ki-67 and cleaved caspase-3 showed that tumor cells were positive for PR, highly proliferative, and less
apoptotic compared to normal breast epithelial cells. Thus, the spontaneous tumor of tree shrew is very close to human
papillary tumors in terms of morphology and pathology and we concluded that tree shrew may be a suitable animal model
for breast cancer research.
