Different growth pattern and biologic behavior of human renal cell carcinoma implanted into different organs of nude mice.

This study was designed to determine the influence of implantation site on the growth of local "primary tumors" and metastatic behavior of human renal cell carcinoma (HRCC) cells. HRCC lines were established in vitro from a surgical specimen (SN12C) or from a liver metastasis produced in BALB/c nude mice by cells from the original specimen implanted into their kidney (SN12L1). Cultured HRCC cells of both lines were injected into the subcutis and the renal subcapsule (RSC) of nude mice. Tumor growth and metastatic behavior were monitored. In both cell lines, tumor cells injected into the RSC displayed faster growth and produced more systemic metastases than did cells injected sc. The kidney tumors were large, invasive, highly vascularized, nonencapsulated, and with minimal central necrosis. In contrast, the subcutaneous tumors were highly encapsulated, with peripheral vascularization and extensive necrosis that developed as early as 2 weeks after sc implantation. The SN12L1 cells were also implanted into nude mice by iv, ip, and intrasplenic injections. The most dramatic production of metastasis occurred after the tumor cells were injected into the kidney. These results indicate that the biologic behavior of this HRCC is influenced by the implantation site in nude mice. At least for the HRCC tested, the kidney is the natural organ for growth. Implantation into the RSC is advantageous for the study of the biology and therapy of HRCC in nude mice.