Characterization of intraperitoneal, orthotopic, and metastatic xenograft models of human ovarian cancer

Improvement of ovarian cancer patient outcome requires well-characterized animal models in which to evaluate novel therapeutics. Xenograft models are frequently used, but with little discussion of disease histology. The objectives of this study were to inject 11 ovarian cancer cell lines intraperitoneally (ip), and a subset intrabursally (ib; orthotopic), into nude mice and to analyze the resulting pathologies. Eight of 11 lines injected ip formed tumors within 3 months at variable rates with the following histological subtype distribution: one endometrioid, one serous, one clear cell, and five undifferentiated. Only mice injected with A2780-cp cells presented with ovarian-specific metastases (11 of 88), and the survival time of these animals was significantly shorter, which may be attributed to the higher proliferation rate as determined by Ki67 positivity. Additional analysis of the influence of the ovarian microenvironment on cell characteristics was conducted with ib injection of two cell lines (OVCA 429 and ES-2). The site of injection did not affect the tumor histology, the effect on proliferation was cell-type dependent, and the tumor take rate (cell survival) was negatively affected for OVCA 429 cells. The animal models described herein represent histologically distinct models of both early and late stage ovarian cancer useful for evaluation of therapeutics.