Maintenance on extracellular matrix and expression of heparanase activity by human ovarian carcinoma cells from biopsy specimens

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Abstract
A routine procedure has been developed for the isolation and maintenance in culture of human ovarian carcinoma cells derived from biopsy specimens. Cell attachment, plating efficiency and initial outgrowth were greatly improved by seeding the cells on a basement‐membrane‐like extracellular matrix (ECM) deposited by cultured corneal endothelial cells. These effects were most significant in serum‐free conditions which markedly reduced the rate of cell attachment and growth on regular tissue culture plastic. In 60–80% of the cases and regardless of the patient's age, cells cultured on ECM in the absence of serum divided actively and formed a tightly packed epithelial cell monolayer. Fibroblast overgrowth and cell detachment often occurred on ECM in the presence of serum. Incubation of the human ovarian carcinoma cells with sulfate‐labelled ECM, resulted in the release of heparan sulfate degradation fragments, 4‐ to 7‐fold smaller than intact heparan sulfate side chains. This degradation was brought about by endoglycosidase (heparanase) activity expressed to a higher extent by cells that were first maintained in primary cultures as compared with cell aggregates taken directly from the biopsy specimen. In most cases, cells derived from metastatic tumors expressed a higher heparanase activity than cells from the primary ovarian tumor. This result corroborates previous studies, performed with cell lines, on the possible involvement of heparanase in tumor cell invasion and metastasis.