Long-term serial transplantation of 30 different human renal cell carcinomas into NMRI (nu/nu) mice: flow cytometric, histologic, and growth studies.

Thirty human renal cell carcinomas were transplanted into NMRI (nu/nu) mice. The take rate from surgical specimens was 100%, and all tumors were established as permanent transplantable tumor lines. The xenotransplants were followed up to around passages 10-50. In addition to histology and volume growth the DNA indices (DI), proportion of tumor cells, and fractions of cells in the phases of the cycle were measured by flow cytometry. All 30 tumors retained their primary histologic structure and cellular morphology throughout all passages. The DI, as ascertained by the DNA content per cell of G1-phase tumor cells divided by the DNA content per cell of normal diploid G1-phase cells, remained the same as those in the original tumors in 21 of 27 xenotransplants. Three original lymph nodes or metastases were not available for flow cytometry. During passage, 4 of 30 tumors changed their DI. In 2 of these cases the tumor doubling time (td), the proportion of tumor cells versus the proportion of host cells, and the fractions of cells in the cell cycle phases changed simultaneously. All other tumor lines were stable in td, DI, proportion of tumor cells, and fractions of cells in the phases during serial transplantation. However, the measure of parameters varied considerably between individual tumors of every passage. Tumor growth rate was generally related to the prognosis of the patients from whom the tumor was derived.