Growth kinetics of primary versus metastatic human melanoma xenografts in nude mice.

Primary and metastatic tumors from a single patient with fatal malignant melanoma were heterotransplanted and maintained in BALBc/Nu mice. Kinetic parameters were determined using tritiated thymidine as a single injection for percent labeled mitoses studies and continuous infusion for growth fraction studies. Tumor growth characteristics in mice were also examined. Karyotyping and ouabain studies showed that the human chromosomes were maintained in serial transplantation and did not form hybrid cells with the mice. Results suggest that while the metastatic cells have longer cell cycle and duration of S phase, they possess other characteristics which permit faster growth and easier transplantation. The possible role of an "angiogenesis factor" in this situation is discussed.