Regulators of Cell Division: Endogenous Mitotic Inhibitors of Mammalian Cells

Lozzio, Bismarck B.; Lozzio, Carmen B.; Bamberger, Elena G.; Lair, Stephen V.

doi:10.1016/s0074-7696(08)60977-8

Cited by 37 publications

(13 citation statements)

References 114 publications

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“…The unidentified inhibitor described above is probably different from those inhibitors reported in the literature to date; a recent review of endogenous inhibitors of mammalian cells has been written by Lozzio et al (12). We have excluded the possibility that the substance is a spermine complex, the major inhibitor in a "lymphocyte chalone" preparation (13).…”

Section: Discussionmentioning

confidence: 86%

Density-dependent regulation of growth of BSC-1 cells in cell culture: growth inhibitors formed by the cells.

Holley¹,

Armour²,

Baldwin³

1978

Proc. Natl. Acad. Sci. U.S.A.

103

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Inhibitors formed by a monkey epithelial cell line, BSC-1, play an important role in limiting growth at high cell densities. At least three inhibitors are formed: lactic acid, ammonia, and an unidentified inhibitor that may be an unstable protein. The unidentified inhibitor is destroyed by shaking the conditioned medium, by bubbling gas through the medium, or by heating or storing the medium in the absence of cells. The concentrations of lactic acid and ammonia that accumulate in conditioned medium inhibit growth when added to fresh medium. These results, together with earlier studies, indicate that density-dependent regulation of growth of BSC-1 cells results from the combined effects of (a) inhibitors formed by the cells, (b) decreased availability of receptor sites for serum growth factors as the cells become crowded, and (c) limiting concentrations of low molecular weight nutrients in the medium. In contrast, density-dependent regulation of growth in 3T3 mouse embryo fibroblasts results almost entirely from inactivation of serum factors.Evidence in the literature suggests that there are differences between the growth controls of epithelial cells and fibroblasts in cell culture (1-4). Due to these differences and to the importance of epithelial cells in the origin of tumors, we have made a thorough study of the factors that control the growth of BSC-1 cells, an epithelial cell line of African green monkey kidney origin (5). In previous papers (4, 6) we demonstrated that (a) serum factors and (b) the concentrations of low molecular weight nutrients in the medium contribute to growth regulation of this cell line. The present paper describes the regulation of growth of BSC-1 cells by the formation of inhibitory materials in the culture medium.The initial evidence for the presence of inhibitors was a slight but consistent stimulation of the labeling index in crowded cells whenever conditioned medium with 0.1% serum was replaced by fresh medium without serum. Although the labeling index along the edge of a "wound" in the cell layer often decreased after this treatment, there was a consistent increase of the labeling index in the crowded cell layer. The-increase could not be attributed to fresh serum factors, for serum was not added.Nor could it be due to an increase in the concentrations of nutrients in the fresh medium: the concentrations of nutrients in conditioned medium were found to be at least half those in fresh medium; changing the cultures to fresh serum-free medium with only half the normal concentrations of the nutrients still stimulated DNA synthesis in the cell layer.Tests of known metabolites identified lactate and ammonium ions as significant growth inhibitors in BSC-1 cell cultures. However, the inhibition observed when these ions were added to fresh medium, at the concentrations found in conditioned medium, was not adequate to explain the above results.Evidence that the cells produce an additional, unidentified inhibitor was obtained initially from experiments in which conditioned medium w...

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Section: Discussionmentioning

confidence: 86%

Density-dependent regulation of growth of BSC-1 cells in cell culture: growth inhibitors formed by the cells.

Holley¹,

Armour²,

Baldwin³

1978

Proc. Natl. Acad. Sci. U.S.A.

103

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“…Most of these have originated from research in immunology or growth regulation. Comprehensive reviews of such factors have appeared recently (Bloom, 1971;Lozzio et al, 1975;Reed and Lucas, 1975). A few of the factors described may be related to the present substance; however, none of them has been reported to be purified to a degree permitting comparison with the substance isolated here.…”

Section: Discussionmentioning

confidence: 99%

“…It has also been suggested that malignant tumours may generate toxic products with general effect on the host, and toxic substances have in fact been isolated from some malignant tumours and tumour effusions (Nakahara, 1967;Holmberg, 1968). However, these theories fail to account for the fact that cachexia may also develop in patients with other grave diseases of some duration (DeWys, 1970).…”

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confidence: 99%

Purification of a cytotoxic factor from human and rat tissues

Op¹

1976

Br J Cancer

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Summary.-Human and rat normal tissues and tumours have been studied for the presence of toxic substances, possibly of importance in the development of cachexia in patients with cancer and other chronic diseases. The toxic effect of tissue extracts was gauged by measuring the inhibition of growth of mouse L-cells in 1 -ml cultures, as revealed by reduced incorporation of ['4C]leucine into cell protein.A common cytotoxic substance of mol. wt. approximately 700 daltons was isolated from all rat and human tissues tested, including tumours. The isolation procedure involved tissue homogenization, followed by pressure dialysis, gel filtration of concentrated pressure dialysates, cation exchange chromatography, and thin layer chromatography. Amounts isolated from different tissues varied by a factor of 3. The purified substance reacted with ninhydrin and a few other reagents for amino groups. It was completely resistant to acid and enzymatic hydrolysis. The evidence thus suggests that the substance is an amine. It is toxic to L-cells, HeLa cells and normal rat fibroblasts in concentrations of 10-20 F&M, producing cell death and lysis during incubation overnight.

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“…One mechanism by which cells in vivo might be maintained'in a nonproliferative state is through the production and secretion into the tissue fluids of growth inhibitors (for a review, see ref. 1). Animal cells are also known to secrete growth stimulators (for reviews, see refs.…”

mentioning

confidence: 99%

Rapid selective effects by a growth inhibitor and epidermal growth factor on the incorporation of [35S]methionine into proteins secreted by African green monkey (BSC-1) cells.

Nilsen-Hamilton¹,

Holley²

1983

Proc. Natl. Acad. Sci. U.S.A.

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Because growth stimulators selectively induce certain secreted proteins, we asked whether growth inhibitors, which antagonize the effects of growth factors on DNA synthesis, act independently to induce other proteins or whether they counteract the effects of growth factors on protein induction. To answer this question, we have worked with an epithelial cell line (BSC-1) derived from African green monkey kidney cells. BSC-1 cells are stimulated to divide by epidermal growth factor (EGF) and are inhibited in DNA synthesis and growth by an inhibitor that is secreted by confluent cultures of the same cells (11).We have found that BSC-1 cells respond to the purified protein growth inhibitor by selectively increasing the rate at which they synthesize and secrete a protein with an approximate Mr of 48,000. These same cells respond to EGF, a growth stimulus, by selectively increasing the rates at which they synthesize and secrete three other proteins with approximate Mrs of 28,000, 59;000, and 62,000. The effects of the growth inhibitor and EGF are additive both in the induction of secreted proteins and on DNA synthesis.MATERIALS AND METHODS Materials. The high molecular weight growth inhibitor was purified by chromatography through Bio-Gel P-60 followed high-performance liquid chromatography as described (11).[S]Methionine was from Amersham, actinomycin D was from Calbiochem, and aprotinin (Trasylol) was from FBA Pharmaceuticals, New York. Cell Culture. BSC-1 cells were cultured as described (12) 5636The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S.C. §1734 solely to indicate this fact.

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Regulators of Cell Division: Endogenous Mitotic Inhibitors of Mammalian Cells

Cited by 37 publications

References 114 publications

Density-dependent regulation of growth of BSC-1 cells in cell culture: growth inhibitors formed by the cells.

Density-dependent regulation of growth of BSC-1 cells in cell culture: growth inhibitors formed by the cells.

Purification of a cytotoxic factor from human and rat tissues

Rapid selective effects by a growth inhibitor and epidermal growth factor on the incorporation of [35S]methionine into proteins secreted by African green monkey (BSC-1) cells.

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