growth and responses to treatment of renal cell carcinoma in different environments.

Renal cell carcinoma is the most common type of kidney cancer in adults and is associated with poor prognosis. The hydrodynamic cell delivery technique was employed in this study to establish tumor growth in mouse lung, liver and kidneys. We demonstrate that Renca cells exhibit different growth rates and responses to the cancer treatment of 5-florouracil and cytokine gene therapy when growing in different organs. The tumor growth rate was faster in the kidneys compared to that in the lung and liver. The liver is the second-best organ in support of tumor growth. Tumors in the liver and lung respond to 5-florouracil treatment but are less responsive in the kidneys. IL-12 gene therapy resulted in whole-body tumor suppression and prolonged animal survival. IFN-β gene therapy was effective in suppressing tumor growth in the liver but not effective for those in the lung and kidneys. These results suggest that kidney cancer cells, once metastasized in different organs, show different growth patterns and respond differently to treatment. Our data also imply that an animal model with multi-organ tumor growth is critical for development of a new strategy for treatment of tumors when metastasis is suspected. At the same time, the results also provide direct evidence in support of the usefulness of the hydrodynamic tail vein injection as a tool for establishment of tumor growth in the lung, liver and kidneys.