The MMTV-PyVT transgene (MMTV-PyMT) includes the mouse mammary tumor virus (MMTV) long terminal repeat upstream of a cDNA sequence encoding the Polyoma Virus middle T antigen (PyVT). Transgenic mice are viable, but show loss of lactational ability coincident with transgene expression. Adenocarcinomas arise in virgin and breeder females as well as males. Tumors are multifocal, highly fibrotic, and involve the entire mammary fat pad. Males also develop adenocarcinoma of the seminal vesicles and hemangiomas. Female carriers develop palpable mammary tumors with a mean latency of 53 days of age, as compared with 92 days in B6.FVB-Tg(MMTV-PyVT)634Mul/LellJ mice (Stock No. 022974). Tumor-bearing females have 80-90% incidence of lung metastasis, a significant increase when compared to that found on the B6 congenic background. Transgene expression is detected at high levels in male and female mammary glands. Lower levels are detected in salivary gland, seminal vesicles, ovaries, and lungs (believed to be the result of pulmonary metastases).
This strain can be used as a platform to alter the tumor microenvironment. Tumor burden and pulmonary metastases have been shown to be reduced after in vivo TMP195 treatment by inducing the recruitment and differentiation of highly phagocytic and stimulatory macrophages within tumors. TMP195 treatment combined with chemotherapy regimens or T-cell checkpoint blockade in this model significantly enhances the durability of tumor reduction.
Of note, this transgene is also available on a congenic C57BL/6 genetic background as Stock No. 022974.
