Correlation of growth capacity of human tumor cells in hard agarose with their in vivo proliferative capacity at specific metastatic sites.

The purpose of this study was to determine whether the degree of anchorage-independent growth of human tumor cells in increasing concentrations of agarose correlated with the capacity of the cells to produce experimental metastases in nude mice. Human melanoma, breast carcinoma, and colon carcinoma cells from parental lines and variants selected in vivo for metastasis and in vitro cloned lines were plated into medium containing 0.3%, 0.6%, 0.9%, or 1.2% of agarose. These cells were also injected into nude mice: intravenously for melanoma, into the mammary fat pad for breast carcinoma, and into the spleen for colon carcinoma. Production of tumor cell colonies in dense agarose (greater than 0.6%) correlated with production of experimental metastases in the lung (melanoma, breast carcinoma) or liver (colon carcinoma). We conclude that the degree of anchorage-independent growth of tumor cells can predict their biological behavior and metastatic potential in vivo. Thus, this technique may be useful for the isolation of metastatic cells from heterogeneous human neoplasms.