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Liver and lung are major target organs for both tumor origination and metastasis. Tumors and metastases may differ in these organs because of their different physiologic conditions. In order to understand the effects of different organ environments, we observed and quantified tumor growth in both liver and lung.

MC38-GFP cells derived from a murine colorectal carcinoma were injected into C57BL6 female mice through the spleen or tail vein for liver and lung colonization experiments respectively. Vessels in each organ were stained with fluorescent antibodies. Isolated organs were imaged with confocal or multiphoton microscopy.

Using 3D reconstructed images we determined tumor cell location with respect to the vasculature at 24, 48 and 72 h after injection. Some cells were found to be entirely intravascular, some were substantially outside the vessel, but with intravascular elements and a minority were entirely extravascular. In the lung approximately 89 to 96 % of tumor cells existed in the vessel at all time points. In contrast, in the liver the percentage that was intravascular decreased from 87 % at 24 h to 54 % at 72 h. Fully extravasated cells were found in the liver. The shape of the proliferating tumor cells was different between cells seeding in the lung and the liver. In the liver the cells were largely spheroid while they appeared oblong and flattened with time in the lung.

These results demonstrate that interactions of tumor cells with host vessels are different during colony development in liver and lung.

98th AACR Annual Meeting-- Apr 14-18, 2007; Los Angeles, CA