A CELL-LINE DERIVED FROM A CLINICALLY BENIGN PHYLLODES TUMOR - CHARACTERIZATION AND IMPLICATIONS

Phyllodes are uncommon tumors of the breast, Improved understanding of their behavior is hampered by the paucity of good laboratory models. We have developed two cell lines, by both xenograft and direct cell cu lture, derived from a histologically benign phyllodes tumor. Both cell lines have the same characteristics and growth kinetics. They grow as monolayers of spindle-shaped cells, with surface markers consistent w ith a mesenchymal origin. They do not express either estrogen or proge sterone receptors. The cells have a relatively short doubling lime of just over 1.5 days, and show a stimulatory effect with the addition of insulin. Karyotype analysis reveals the absence of one X chromosome.