The effects of glycosaminoglycans and several enzymes on the integrity of the human placental amnion and the consequent effects on the permeability of this structure to virally transformed cells and their parent line were examined. Treatment of the amnion with hyaluronate, heparin, and chondroitin ABC lyase affected the structure of both the epithelium and the extracellular matrix and resulted in a significant increase in tumor cell invasion, but it had no significant effect on the invasion of the parent cell line. These polymers promoted the disorganization of the epithelial cell layer, and their presence resulted both in the matting of collagen fibrils in the stroma and in the loosening of the basement membrane. Pronase treatment removed epithelial cells and stripped collagen fibrils of granules, but it did not promote tumor or parent cell invasion, perhaps as a result of loss of attachment factors. Chondroitin sulfate did not affect the epithelial structure or the rate of tumor invasion and had only slight effects on the structure of the basement membrane and the stroma. These results are consistent with the thesis that the continuity of epithelium is critical to resisting tumor cell invasion and suggest that glycosaminoglycans, in addition to certain enzymes, can alter this integrity.
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Turley et al. (1987) studied this question.