A genetically engineered ovarian cancer mouse model based on fallopian tube transformation mimics human high-grade serous carcinoma development. Mus musculus

Recent evidence suggests that ovarian high-grade serous carcinoma (HGSC) originates from the epithelium of the fallopian tube. However, most mouse models are based on the previous prevailing view that ovarian cancer develops from the transformation of the ovarian surface epithelium. Here, we report the extensive histological and molecular characterization of the mogp-TAg transgenic mouse, which expresses the SV40 large T-antigen (TAg) under the control of the mouse müllerian-specific Ovgp-1 promoter. Histologic analysis of the fallopian tubes of mogp-TAg mice identified a variety of neoplastic lesions analogous to those described as precursors to ovarian HGSC. We identified areas of normal appearing p53-positive epithelium that are similar to “p53 signatures” in the human fallopian tube. More advanced proliferative lesions with nuclear atypia and epithelial stratification were also identified that were morphologically and immunohistochemically reminiscent of human serous tubal intraepithelial carcinoma (STIC), a potential precursor of ovarian HGSC. Beside these noninvasive precursor lesions, we also identified invasive adenocarcinoma in the ovary of 56% of the mice. Microarray analysis revealed several genes differentially expressed between the fallopian tube of mogp-TAg and WT C57BL/6. One of these genes, Top2a, which encodes topoisomerase II-alpha, was shown by immunohistochemistry to be concurrently expressed with elevated p53 and specifically elevated in mouse STICs, but not in surrounding tissues. TOP2A protein was also found elevated in human STICs, low-grade, and high-grade serous carcinoma. The mouse model reported here displays a progression from normal tubal epithelium to invasive HGSC in the ovary, and therefore closely simulates the current emerging model of human ovarian HGSC pathogenesis. This mouse therefore has the potential to be a very useful new model for elucidating the mechanisms of serous ovarian tumorigenesis, as well as for developing novel approaches for the prevention, diagnosis, and therapy of this disease. Keywords: transgenic mouse model, ovarian cancer, fallopian tube, intraepithelial carcinoma Overall design: 6 mouse fallopian tubes (FT) were analyzed with experimental repeats; 3 wildtype C57BL6 mice (FT) and 3 transgenic mogp-TAg (FT), with one set of each at 7, 8 and 9 weeks of age.