Organ specificity of metastatic tumor colonization is related to organ-selective growth properties of malignant cells.

In cancers such as malignant melanoma, tumor spread or metastasis occurs preferentially to certain organ sites. Mouse B16 melanoma cell sublines that have been selected sequentially in vivo for enhanced blood-borne colonization of lung, brain, or ovary were tested for their survival and growth stimulation in vitro by soluble factors released from suspensions of mouse lung, brain, liver, ovary or kidney tissues. In general, the growth rate of lung-colonizing B16 cells was stimulated by high concentrations of lung-tissue-derived factors significantly more than by factors from the other tissues, whereas the growth rate of ovary-colonizing B16 cells was stimulated by ovary or lung-tissue-derived factors significantly more than by factors from the other tissues. In contrast, the growth of brain-colonizing B16 cells was not stimulated by factors released from brain tissue. When it occurred, stimulation of B16 cell growth by factors released from mouse organ tissues was dose-dependent. Liver tissue factors, and at high concentrations kidney tissue factors, inhibited cell growth of the B16 sublines, an inhibition correlating with the low potential of B16 cells to colonize liver and kidney in vivo. In addition to preferential target-organ cell adhesion found previously with B16 sublines (Nicolson et al., 1985a), the present results suggest that metastasis to specific organ sites is also dependent on the survival and growth of B16 cells affected by soluble organ-derived factors.