Serum-dependent growth patterns of two, newly established human mesothelioma cell lines.

Two cell lines with different in vitro growth patterns were established from the pleural fluid of a patient with malignant epithelial pleural mesothelioma. The cell line established in RPMI 1640 supplemented with human AB serum had an epithelial morphology, while the cell line established in fetal calf serum-supplemented medium had a fibroblast-like morphology. Exposure of the fibroblast-like cell line to human AB serum-containing medium resulted in a nearly complete transformation of the morphology to the epithelial-like phenotype, and the epithelial-like cell line changed its phenotype to fibroblast-like upon exposure to fetal calf serum-supplemented medium. Both cell lines formed colonies in soft agarose and secreted hyaluronic acid into the culture medium. In both cell lines all the metaphases studied lacked chromosomes 5 and 9, demonstrating the same clonal origin. However, one marker and a missing chromosome 11 were found only in the fibroblast-like cell line. We conclude that human AB serum supplement can be used for the establishment of human tumor cell lines, and that the choice of serum can affect the in vitro morphology of the established mesothelioma cell lines. The mechanisms behind the different growth patterns seem to be a selective stimulation of different subpopulations of malignant cells as well as induction of changes in the morphology of individual cells.