Attachment and invasion of high- and low-metastatic clones of RCT sarcoma in a three-dimensional culture system.

High- and low-metastatic clones established from poorly differentiated murine sarcoma (RCT sarcoma) spontaneously developed in C3H/He mice were used in this study. Attachment and invasion, which are factors likely related to metastatic ability, of these clones were investigated in a three-dimensional culture system using embryonic chick heart fragments and tumor cell aggregates. The effects of Nocodazole, which interferes with the function of microtubules, and cytochalasin B, which affects the actin assembly in cytoplasmic extensions, on these factors were also examined. Metastatic ability was correlated with attachment and invasiveness of RCT sarcoma. Invasiveness of tumor cells was suppressed by the addition of Nocodazole to the culture medium. Since the disappearance of cell polarity, resulting from the inhibition of tubulin assembly, was found to coincide with the suppression of invasion, directional migration is considered to be involved in the invasion of tumor cells. Cytochalasin B caused a marked decrease in the ratio of attachment of tumor aggregates to embryonic chick heart fragments. The increased ability of invasion and attachment of RCT(+) cells compared with RCT(-) cells seems to contribute to their propensity to metastasize.