Junctional communication of highly and weakly metastatic variant clones from a rat mammary carcinoma in primary and metastatic sites.

: We have investigated junctional intercellular communication (JC) in primary and metastatic sites, using two highly and two weakly metastatic variant clones which had been isolated from a rat mammary carcinoma cell line, c-SST-2. After each variant had been subcutaneously inoculated into syngeneic rats, tumor cells were isolated from local tumor (primary tumor) and their metastatic foci (lung, heart and kidney). The cells were then recultured, and we measured their JC in vitro by the dye transfer method with the fluorescent dye Lucifer yellow CH, and found that the homologous (tumor cell-tumor cell) JC of highly metastatic clones were less in recultured tumor cells from primary tumors than that of weakly metastatic clones. At the same time, the heterologous (tumor cell-normal fibroblast) JC of highly metastatic clones was less than that shown by weakly metastatic clones. On the other hand, tumor cells obtained from metastatic foci showed relatively reduced JC (homologous and heterologous) when compared with those from their primary tumors in the weakly metastatic clones. These data suggest that a decrease in and/or a loss of JC may play a role in the expression of metastatic properties.