Extracellular material secreted by human colonic adenocarcinoma cell lines promotes spreading in serumfree medium and induces neurite outgrowth of PC‐12 cells

A completely defined medium has been designed to promote cell proliferation of 2 colonic adenocarcinoma cell lines of epithelial origin (HT 29 and HRT 18). The spreading of both cell types, especially of HT 29 cells, was not possible in a serum‐free medium supplemented with growth factors. Spreading was obtained in a defined medium (a I/I mixture of DMEM and F12 media supplemented with 5 μ g/ml transferrin, 5 ng/ml EGF, 10 ng/ml selenite and 15 mM HEPES PH 7.3) with an extracellular matrix‐like material (ECM) secreted by the cells themselves. The properties of the ECM have been studied: (I) ECM secreted by the 2 cell lines induced very quick spreading of HT 29 and HRT 18 cells (1 to 2 hr vs. 12 to 24 hr in serum‐supplemented medium). (2) ECM induced morphological differentiation of a rat pheochromocytoma cell line (PC 12). PC‐12 cells grown under these conditions began to develop neurite extensions as early as 2 hr after seeding.