Abstract C91: PyVmT luminal and EMT cell lines exhibit characteristic patterns of orthotopic and tail vein metastasis

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Abstract Understanding pathways leading to metastasis remains a primary goal of breast cancer research. Epithelial to mesenchymal transition (EMT) is thought to be critical in this process as tumor cells migrate through the stroma and undergo deformation while passing endothelial cells to enter the circulation. To examine the role of EMT in tumor metastasis, we have developed a number of stable cell lines in polyomavirus middle T (PyVmT) mammary tumors congenic in the C57Bl/6 background. In this study we characterized the metastatic properties of a luminal cell line Py230 and an EMT cell line Py8119, both of which have cancer stem cell properties of self-renewal, differentiation and tumor initiation. Py230 cells form well-differentiated epithelial adenocarcinomas typical of the spontaneous PyVmT model when injected orthotopically. Injection of 1-10 cells at a single site can give rise to 1-2 metastases over a period of approximately 20 weeks, however the number of metastases can be increased and the duration of the experiment reduced, by injecting 106 cells at 4 sites and removing the tumors at 5-6 weeks when they reach 7-8 mm diameter. After an additional 4-5 weeks multiple lung metastases are visible. Multiple lung metastases can also be achieved by tail vein injection of 5 x 105 cells and inflammation plays a role in the growth at this site as a significant reduction in metastasis is observed in mice lacking the inducible nitric oxide synthase. No Py230 tumor metastases are found in other tissues such as liver, kidney or spleen either with orthotopic or tail vein injection. In contrast, Py8119 cells form highly invasive, poorly differentiated claudin low EMT tumors upon injection into the mammary fat pad. The tumors grow rapidly, but excision does not result in lung metastasis despite their highly invasive phenotype, indicating that EMT alone is not sufficient for metastasis from the mammary fat pad. However, when the cells are injected into the tail vein, metastases develop at multiple tissue sites including lung, liver, kidney and spleen. Py8119 cells upregulate markers of EMT including twist, sna1, sna2 and MMP2 in comparison to Py230 cells, but whether Py230 cells undergo transient EMT and MET during metastasis is currently unknown. Additional luminal or EMT cell lines exhibit similar patterns of metastasis to the Py230 and Py8119 cell lines respectively. Since the majority of human breast cancers are luminal and the less frequent claudin low tumors have a poor prognosis, both the Py230 and Py8119 cell lines should be a useful in dissecting pathways of metastasis relevant to human breast cancer. Citation Format: Lesley G. Ellies, Christopher Kuo. PyVmT luminal and EMT cell lines exhibit characteristic patterns of orthotopic and tail vein metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr C91.