Inhibition of embryonic cell aggregation by neoplastic cells.

The effects of normal and malignant cells on the aggregation of embryonic cells in gyratory shaker cultures were compared. The addition of 1 times 10-5 simian virus 40 (SV40)-transformed BALB/3T3 (SV40-3T3) cells to 6 times 10-6 embryonic neural retina cells caused a highly significant greater reduct on (22.7 percent) in aggregate diameter than the addition of untransformed BALB/3T3 (3T3) cells. The ratio of the number of single cells to the number of aggregates was significantly higher for cultures containing SV40-3T3 cells than for the cultures containing 3T3 cells. This effect was concentration dependent in the presence of cultured Ehrlich-Lettre hyperdiploid (ELD) ascites cells; however, media from ELD cell cultures or ELD cell sonicates resulted in aggregates of greater diameter and lower ratios of single cells to aggregates. This approach may provide a sensitive assay system for the interactions of tumor and other cells in vitro.