Isolation and characterization of metastatic sublines from a murine transitional cell bladder carcinoma

Four sublines of a murine N-[4-(5-nitro-2-furyl)-2-thiazolyl]-foramide (FANFT)-induced transitional cell carcinoma (MBT-2) possessing spontaneous metastatic ability were isolated via in vivo/in vitro serial selection of metastatic lung lesions. Subcutaneous inoculation of the parent cell line (MBT-2) produced primary tumors when injected into C3H mice. These primary tumors rarely metastasize. A subline designated L3F1 was established from 1 MBT-2 pulmonary metastatic tumor. Further in vivo/in vitro selections established three additional sublines designated L3F2, L3F3 and L3F4. Serial selection resulted in MBT-2 sublines of greater metastatic potential in terms of both incidence of metastasis and the number of metastatic tumors per lung. The parent line differed from the four sublines in metastatic potential, in vitro cell morphology, and in vitro growth parameters. The L3F2 subline was examined for the time of onset of metastasis by removal of the primary tumor. Metastasis of the subcutaneously transplanted tumor occurred between 14 and 21 days after injection of the L3F2 subline. The L3F2 primary tumors and lung metastases were morphologically characterized by light and electron microscopy.