Glycosaminoglycan-sac formation in vitro. Interactions between normal and malignant cells.

The interaction of monolayer normal human or normal rat cells with suspension Walker rat tumor cells was demonstrated cytologically, during a cocultivation period of thirty days. At ten days, Walker rat tumor cells were interiorized in the cytoplasm of the normal monolayer host cells. At twenty days, degeneration of the interiorized tumor cells followed by mucification led to glycosaminoglycan-sac formation. At thirty days, tumor nodules and protease (alpha 1-chymotrypsin)- bound glycosaminoglycan(s) extracellular matrix, transversing the culture in membranous rivulets, were formed. The overall interaction resulted in the death of the interiorized tumour cell and survival of the normal host cells containing a glycosaminoglycan-sac. The use of bladder tumor cell imprints showed that cell interiorization, degeneration and extracellular matrix formation identical to that of the co-cultures, also occur in vivo. Cell interiorization within malignant cell cultures led to syncytia formation and survival of both host and interiorized cells. Identical glycosaminoglycan extracellular matrix to that of the co-cultures and syncytia was also observed in smears of EBV-producing (P3HR-1) cell cultures. The observations are discussed in terms of invasion, emperipolesis, cannibalism, phagocytosis and extracellular matrix. It is concluded that a glycosaminoglycan-sac is produced by the interiorization of a tumor cell into a normal cell while interiorization of a tumor cell into another tumor cell resulted in syncytia formation.