Adhesion of frog pronephric tumor cells to normal cells cultivated on microcarrier beads

The processes of cell adhesion and active spreading were assessed between frog normal pronephric, pronephric tumor and heterologous liver cells. Confluent monolayers were developed on collagen-coated microcarrier beads, then exposed to homologous or heterologous cells and cultivated with a rotary (orbital) flask culture technique at 23 degrees C. All three cell lines attach and actively spread on the collagen-coated microcarrier beads. Secondary attachment of normal (non-transformed) proliferating cells to their confluent monolayers occurs but cell spreading is restrained. Dissociated pronephric tumor cells adhere and actively spread on the surfaces of normal pronephric cells, and eventually encapsulate them. Normal pronephric cells do not adhere readily to the cell surfaces of pronephric tumor cells grown on microcarrier beads. Tumor cells also attach, actively spread and overgrow heterologous liver cells attached to microcarrier beads. Suboptimal temperatures (17 degrees C) slow tumor cell attachment and spreading on normal cells. Colder temperature (8 degrees C) permits tumor cell attachment and adhesion to normal cell-coated beads but active cell spreading is prohibited. The same temperature retards cell spreading directly on the collagen-coated beads.