A serum-free medium with or without a carrier protein supports the growth of the Y-1 mouse adrenocortical cell line and its steroidogenic function.

The development of a method for the serum-free culture of the Y-1 mouse adrenocortical tumor cell line has permitted a detailed search for factors regulating cellular growth and steroidogenesis. The serum-free medium (SFM) was made of Ham's F10 basal medium supplemented with free fatty acids adsorbed on albumin. The SFM complemented with calcium, arachidonic acid and cholesterol, i.e. SFM-S, induced cell proliferation to a density at confluency higher than that obtained with 1% serum-supplemented medium (1%-SSM) and allowed to sustain cell growth for more than six passages. When albumin was replaced by a dextran polymer (Mr = 2 x 10(6)) used as a carrier of lipids instead of albumin (which resulted in a serum-free and protein-free medium, SPFM), the cell number was 75% of that observed with the SFM-S. The addition to SPFM of beta-globulin alone or combined with insulin caused a 2- or 3-fold increase in the final cell density, respectively. The ability of the Y-1 cell line to produce steroids in response to ACTH was found to be higher in SFM-S or SPFM than in 1%-SSM. Furthermore, the addition of beta-globulin to SPFM stimulated steroid hormone biosynthesis with a marked increase in 11 beta-hydroxylated steroid production. These studies demonstrate that the use of a defined mixture of nutriments and of few growth factors permits to sustain not only the cellular proliferation of the Y-1 cell line but also its differentiated function of ACTH-induced steroidogenesis.