Site-specific metastasis of mouse melanomas and a fibrosarcoma in the brain or meninges of syngeneic animals.

Different subpopulations of cells from two different murine melanomas (K-1735 and B16) and a fibrosarcoma (UV-2237) were injected into the internal carotid artery of anesthetized syngeneic mice. Despite the common route of tumor cell injection, tumor lesions in the brain were unique to each tumor type and developed at different sites in the brain. Gross and histological examinations revealed that different subpopulations of cells derived from the K-1735 melanoma produced only parenchymal lesions, cells of the B16 melanoma produced lesions in the meninges and ventricles, and cells of the UV-2237 fibrosarcoma produced lesions throughout the brain. This site specificity for tumor growth was not due to the initial tumor cell arrest in the microvasculature of different regions-areas in the brain as evidenced by detailed studies with radiolabeled cells. The site specificity of this experimental brain metastasis was not random and correlated well with the clinical situation. The exact interactions of tumor cells with different microenvironments in the brain need further elucidation.