Purification of kidney epithelial cell growth inhibitors.

Abstract

Two high molecular weight growth inhibitors have been isolated from the culture medium of BSC-1 cells, epithelial cells of African green monkey kidney. The purified kidney epithelial cell growth inhibitors, at ng/ml concentrations, reversibly arrest the growth of BSC-1 cells in the GI phase of the cell cycle. Their action is selective; they are most active on BSC-1 cells, are less active as inhibitors of the growth of rat lung and human breast epithelial cells, and do not inhibit the growth of 3T3 mouse embryo fibroblasts and human skin fibroblasts in culture. Their growth inhibitory action on BSC-1 cell cultures is counteracted by epidermal growth factor or calf serum.One of the areas of ignorance that remains in our broad understanding of the control of growth of mammalian cells is the subject of endogenous growth inhibitors. The existence of a number of growth inhibitors has been postulated (1, 2), and growth-inhibitory fractions have been obtained from various mammalian cells and tissues (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Nevertheless, there are doubts as to the significance of endogenous growth inhibitors because most of the inhibitor preparations have low specific activity, the inhibitors have been difficult to purify, and with some preparations the causes of growth inhibition have, at least in part, turned out to be trivial (15-17). There is no doubt that highly active growth inhibitors exist for mammalian cells, because interferon and corticotropin are extremely active as growth inhibitors in certain cell cultures (18,19), but the inhibitory activities of these two substances could be incidental to their other biological activities. Because of the potential significance of growth inhibitors and because purified inhibitors could be very useful in the manipulation of growth of mammalian cells, we have undertaken further studies in this area.Density-dependent regulation of growth of BSC-1 cells (African green monkey kidney epithelial cells) has been found to result in part from the accumulation of growth inhibitors in the culture medium (20). The present paper describes the isolation of high molecular weight growth inhibitors from the culture medium of these cells. The growth inhibitors have very high specific activities, approximately equal to the specific activities of interferon and corticotropin in their respective cell culture assays. The new growth inhibitors appear to be selective in the types of cells on which they act. MATERIALS AND METHODSCell Cultures. BSC-1 cell stock cultures were maintained as previously described (21) in Dulbecco's modified Eagle's medium (DME medium) (22) Preparation of Conditioned Medium. Dense BSC-1 cell cultures, used for preparation of conditioned medium, were grown in 15-cm Falcon tissue culture plates in DME medium with 1% calf serum. The medium was changed once a week until the cells reached a density of approximately 1.5 X 105 cells per cm2. The cultures were then maintained in DME medium with 0.1% calf serum. To prepare conditioned medium, the cultu...

Growth control in cultured 3T3 fibroblasts: neutralization and identification of a growth-inhibitory factor by a monoclonal antibody.

“…4, compo In addition, it would be of obvious interest to establish the relationship between the Mr 13,000 polypeptide in FGR-s and similar growth-inhibitory activities reported in other systems. These include (i) the membrane-bound growth-inhibitory activities of 3T3 cells reported by Glaser (13,14), Peterson (15,16), and Datta (17,18) and their co-workers; (ii) the highly purified growth-inhibitory factor from medium of BSC-1 cells (19,20); (iii) the hepatic proliferation inhibitor (Mr, 26,000; pI, 4.65) isolated from normal rat livers (21,22); and (iv) the growth-inhibitory glycopeptides identified and partially purified from mouse and bovine cerebral cortex cells (23,24). More recently, it has been shown that secondary cultures of mouse embryo fibroblasts release into the medium a growth-inhibitory activity whose physicochemical behavior closely parallels that of FGR-s (25) and that a growth inhibitor for Ehrlich ascites mammary carcinoma cells can be isolated from the bovine mammary gland (26).…”

Purification and properties of a rat liver protein that specifically inhibits the proliferation of nonmalignant epithelial cells from rat liver.

“…In contrast, little is known about the role of growth inhibitory factors, although they clearly are involved in the control of cell proliferation which itself is critical in the carcinogenic process as discussed in depth by Potter (4,5). Considerable literature is available on the existence ofinhibitors ofcell proliferation in different cells and tissues (6)(7)(8)(9)(10)(11)(12)(13)(14)(15), but such factors from normal tissues have not been purified.…”

A retrovirus expressing the 12S adenoviral E1A gene product can immortalize epithelial cells from a broad range of rat tissues.

“…Unlike fibroblasts, many epithelial cell types will not grow in high concentrations of serum, perhaps owing to the presence of one or more inhibitory factors (2,12, 20). Although some oncogenic viruses have been useful for the transformation of specific differentiated cell types in vitro, such as the transformation of pre-B cells by Abelson virus (34), no viruses have been consistently successful in the transformation of diverse epithelial cells (33).…”