In vitro degradation of extracellular matrix by human ovarian carcinoma cells

Better in vitro models are needed to elucidate the mechanisms underlying tissue destruction by human tumor cells. To address this matter recently isolated and characterized human ovarian carcinoma cell lines derived from either primary tumors, ascitic effusions or metastatic growths were plated in direct contact with extracellular matrix (ECM) previously deposited on culture dishes by bovine corneal endothelial cells. Light and electron microscopy of four of the five ovarian tumor cell lines demonstrated morphologic digestion with penetration of ECM by tumor cell microvilli, along with associated rarefaction. The ability of these same ovarian tumor cell lines to solubilize specific carbohydrate and protein moieties present in intact ECM was assessed with the use of metabolically prelabeled ECM employing tritiated fucose, galactose, glucosamine and proline. Results from these studies corroborated morphologic observations in which four of the five tumor cell lines tested extensively solubilized radiolabeled ECM. The kinetics of radiolabel release from ECM illustrated that three of the four invasive tumors released [3H]fucose, [3H]glucosamine and [3H]proline at high rates. Normal human ovarian fibroblasts and mesothelial cells were observed to be unable to digest ECM and this was consistent with their inability to release radiolabeled material from prelabeled ECM. The results from these studies suggest that some ovarian carcinomas have the ability to degrade basement membrane components. Knowledge regarding the mechanisms responsible for tissue degradation may eventually lead to the development of new chemotherapeutic modalities designed to restrict tumor cell invasion, growth and metastasis.