To examine the specific effects of individual basement membrane components on the behavior of transformed cells of epithelial origin, ethionine-transformed cells and control cells at low and high passage levels were seeded on glass that had been coated with fibronectin, laminin, or type IV collagen. The cells used were sublines of the liver-derived TRL 1215 epithelial cell line, a line in which transformation has been shown to be accompanied by increased cell-substrate adhesion and cell spreading. Cell spreading on the different basement membrane components was determined by morphometry, and growth (proliferation) was measured by protein and DNA analyses. Laminin increased spreading and growth in transformed and control sublines. Laminin also induced changes in cell shape that were indicative of increased cell motility. For the control cells, fibronectin and also type IV collagen were less effective than laminin in stimulating cell spreading and growth. However, for the ethionine-transformed cells, fibronectin was as effective as laminin in stimulating cell spreading. With the exception of the spreading response to fibronectin, the ethionine-transformed cells were less sensitive to the defined substrata than were the control sublines. Moreover, only the ethionine-transformed cells were able to proliferate in serum-free medium. Thus, greater autonomy is characteristic of transformation for these epithelial cells and is exemplified by the reduced influence of and dependence on exogenous factors, both substrate-bound and soluble, for spreading and growth.

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