Showing papers on "Cell growth published in 1981"

The Saccharomyces cerevisiae Cell Cycle

Abstract: INTRODUCTION The cell cycle is the process of vegetative (asexual) cellular reproduction; in a normal cell cycle, one cell gives rise to two cells that are genetically identical to the original cell. Questions about the cell cycle can be conveniently divided into two categories. First, one can ask how a cell carries out a cell cycle, once it has undertaken to do so. Into this category fall questions about the morphological and biochemical aspects of cell-cycle events and about the mechanisms that ensure their temporal and functional coordination. Second, one can ask what determines when a cell will undertake a cell cycle, or how the overall control of cell proliferation is achieved. Into this category fall questions about the coordination of successive cell cycles, the coordination of growth with division, the coordination of cell proliferation with the availability of essential nutrients, and the selection of developmental alternatives. In the text that follows, we consider these two categories of questions in turn. Our bibliography is intended more as a guide to the literature than as a historically accurate record of the development of the field; we apologize to the earlier workers whose contributions thus get less explicit credit than they deserve. HOW DOES A CELL CARRY OUT A CELL CYCLE? As has often been noted, successful completion of a cell cycle requires a cell to integrate the processes that duplicate the cellular material with the processes that partition the duplicated material into two viable daughter cells. Another useful formulation of the...

Effects of sodium butyrate, a new pharmacological agent, on cells in culture

Abstract: Sodium butyrate, at millimolar concentrations, when added to cell cultures produces many morphological and biochemical modifications in a reversible manner. Some of them occur in all cell lines. They concern regulatory mechanisms of gene expression and cell growth: an hyperacetylation of histone resulting from an inhibition of histone deacetylase and an arrest of cell proliferation are almost constantly observed. Some other modifications vary from one cell type to another: induction of proteins, including enzymes, hormones, hemoglobin, inhibition of cell differentiation, reversion of transformed characteristics of cells to normal morphological and biochemical pattern, increase in interferon antiviral efficiency and induction of integrated viruses. Most if not all these effects of butyrate could result from histone hyperacetylation, from changes in chromatin structures as measured by accessibility to DNases and from modifications in cytoskeleton assembly. We do not know at the present time whether butyrate acts on a very specific target site in cell or if it acts on several cell components.

Gene required in G1 for commitment to cell cycle and in G2 for control of mitosis in fission yeast.

Abstract: The control regulating commitment to the cell division cycle of eukaryotes seems to occur before the initiation of DNA replication1–4. In the budding yeast Saccharomyces cerevisiae, this control is called start and is the earliest gene-controlled event of the cell cycle3–5. A haploid cell which has completed start is committed to cell division and unable to undergo alternative developmental fates such as conjugation. Here, we describe an analogous start control in the fission yeast Schizosaccharomyces pombe. We have tested the ability of cdc mutants blocked at various stages of the cell cycle to undergo conjugation. Only mutants of cdc 2 and cdc 10 which block during the G1 period are able to conjugate. Other mutants which block during G1, S phase, G2 or mitosis are committed to cell division and cannot conjugate. The commitment control start is located in G1, and its completion requires the gene functions of cdc 2 and 10. Completion of start occurs at the beginning of the cell cycle in rapidly growing cells, but is delayed to later in the cell cycle at slow growth rates. The cdc 2 gene function also participates in another major cell cycle control which determines the timing of mitosis6–8. Therefore cdc 2 is a cell cycle control gene which acts at two separate points in the cell cycle: it is required in G1 for commitment to cell division and in G2 for the control of mitosis.

Human cell surface glycoprotein related to cell proliferation is the receptor for transferrin.

Abstract: A cell surface glycoprotein antigen with an apparent molecular weight of about 100,000 that is selectively expressed on proliferating cells was purified from deoxycholate-solubilized membranes of a cultured human leukemic thymus-derived (T) cell line by affinity chromatography on a monoclonal antibody-Sepharose column. A conventional xenoantiserum prepared by immunization with the affinity-purified glycoprotein was found to contain antibodies against a serum component that bound tightly to cultured cells. This molecule was shown to be specifically associated with the cell surface glycoprotein purified by immunoprecipitation from lysates of cells. We have identified the serum component as transferrin and conclude that the membrane glycoprotein is the cell surface transferrin receptor.

Cultured endothelial cells produce heparinlike inhibitor of smooth muscle cell growth

Abstract: Using cultured cells from bovine and rat aortas, we have examined the possibility that endothelial cells might regulate the growth of vascular smooth muscle cells. Conditioned medium from confluent bovine aortic endothelial cells inhibited the proliferation of growth-arrested smooth muscle cells. Conditioned medium from exponential endothelial cells, and from exponential or confluent smooth muscle cells and fibroblasts, did not inhibit smooth muscle cell growth. Conditioned medium from confluent endothelial cells did not inhibit the growth of endothelial cells or fibroblasts. In addition to the apparent specificity of both the producer and target cell, the inhibitory activity was heat stable and not affected by proteases. It was sensitive flavobacterium heparinase but not to hyaluronidase or chondroitin sulfate ABC lyase. It thus appears to be a heparinlike substance. Two other lines of evidence support this conclusion. First, a crude isolate of glycosaminoglycans (TCA-soluble, ethanol-precipitable material) from endothelial cell-conditioned medium reconstituted in 20 percent serum inhibited smooth muscle cell growth; glycosaminoglycans isolated from unconditioned medium (i.e., 0.4 percent serum) had no effect on smooth muscle cell growth. No inhibition was seen if the glycosaminoglycan preparation was treated with heparinase. Second, exogenous heparin, heparin sulfate, chondroitin sulfate B (dermatan sulfate), chondroitin sulfate ABC, and hyaluronic acid were added to 20 percent serum and tested for their ability to inhibit smooth muscle cell growth. Heparin inhibited growth at concentrations as low as 10 ng/ml. Other glycosaminoglycans had no effect at doses up to 10 μg/ml. Anticoagulant and non- anticoagulant heparin were equally effective at inhibiting smooth muscle cell growth, as they were in vivo following endothelial injury (Clowes and Karnovsk. Nature (Lond.). 265:625-626, 1977; Guyton et al. Circ. Res. 46:625-634, 1980), and in vitro following exposure of smooth muscle cells to platelet extract (Hoover et al. Circ. Res. 47:578-583, 1980). We suggest that vascular endothelial cells may secrete a heparinlike substance in vivo which may regulate the growth of underlying smooth muscle cells.

N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide, a calmodulin antagonist, inhibits cell proliferation

Abstract: N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) and its derivatives are putative calmodulin antagonists that bind to calmodulin and inhibit Ca2+/calmodulin-regulated enzyme activities Autoradiographic studies using tritiated W-7 showed that this compound penetrates the cell membrane, is distributed mainly in the cytoplasm, and inhibits proliferation of Chinese hamster ovary K1 (CHO-K1) cells Cytoplasmic [3H]W-7 was excluded completely within 6 hr after removal of [3H]W-7 from the culture medium N-(6-aminohexyl)-1-naphthalenesulfonamide, an analogue of W-7 that interacts only weakly with calmodulin, proved to be a much weaker inhibitor of cell proliferation CHO-K1 cells were synchronized by shaking during mitosis and then released into the cell cycle in the presence of 25 microM W-7 or 25 mM thymidine for 12 hr Cell division was observed approximately 6 hr later The results suggest that the effect of W-7 on cell proliferation might be through selective inhibition of the G1/S boundary phase, which is similar to the effect of excess thymidine This pharmacological demonstration that cytoplasmic calmodulin is involved in cell proliferation is significant; W-7 and its derivatives may be useful tools for research on calmodulin and cell biology-related studies

1,25-dihydroxyvitamin D3 and malignant melanoma: the presence of receptors and inhibition of cell growth in culture.

Abstract: In this study we demonstrate the presence of specific, high-affinity receptors for 1,25-dihydroxyvitamin D3 in malignant melanoma. Receptors are present both in cultured melanoma cells and in melanoma tumor tissue produced by inoculation of cells into athymic rats. The receptor sediments at 3.25 on sucrose density gradients, possesses a preferential affinity for 1,25-(OH)2D3 and has an apparent Kd of 0.18 nM by Scatchard analysis. We also demonstrate that human melanoma cells are responsive to 1,25-(OH)2D3 in vitro. Inclusion of 1,25-(OH)2D3 in the culture medium produced a marked increase in cell doubling time. This inhibitory effect of the hormone on melanoma cell proliferation was dose-related and represents the first demonstration of a 1,25-(OH)2D3 mediated action on tumor cells.

A nuclear antigen associated with cell proliferation and blast transformation.

Abstract: A nuclear antigen associated with cell proliferation (proliferating cell nuclear antigen-PCNA) and blast transformation is recognized by autoantibodies in the sera of some patients with systemic lupus erythematosus This autoantibody is a precipitating antibody and also reacts in immunofluorescence, staining the nucleoplasm of proliferating and blast-transformed cells The autoantibody was used as a reagent to determine the distribution of PCNA in a synchronized continuous B lymphoid cell line (WiL-2) and in mitogen-induced blast-transformed lymphocytes In WiL-2 cells, PCNA was detected as speckled nucleoplasmic staining in G1, S, and G2 phases of the cell cycle In addition, during late G1 and early S phases, PCNA was also detected in the nucleolus During mitogen-induced blast transformation of lymphocytes, PCNA was noticed in the nucleolus before the initiation of DNA synthesis and later became nucleoplasmic with disappearance of nucleolar staining These studies demonstrate that the relationship of PCNA to proliferation and blast transformation may be associated with events related to DNA synthesis in these cells

Regulation of T cell differentiation: in vitro induction of 20 alpha-hydroxysteroid dehydrogenase in splenic lymphocytes from athymic mice by a unique lymphokine.

Abstract: The enzyme 20 alpha-hydroxysteroid dehydrogenase (20 alpha SDH) has previously been shown to be a specific enzyme marker of mature T cells. In vivo, the expression of 20 alpha SDH is thymus dependent, in that splenic lymphocytes from athymic mice have only low levels of activity, although the levels of enzyme activity increase gradually with age. In vitro, 20 alpha SDH can be induced in splenic lymphocytes from nu/nu mice by conditioned media from mitogen- or alloantigen-stimulated normal lymphocytes. Induction is rapid in vitro. Beginning after a lag period of approximately 6 hr, enzyme activity increases linearly for approximately 20 to 30 hr resulting in a 5- to 10-fold increase in activity. Induction is blocked by mitomycin C, suggesting a requirement for cell proliferation. The phenotype of both the precursor and the induced lymphocyte populations is Thy 1.2-, Lyt 1-, 2-, suggesting that induction of 20 alpha SDH expression is an early step in T cell differentiation. The factor responsible for 20 alpha SDH induction has been partially purified and is distinct from other known lymphokines in both its biochemical and functional properties. The term interleukin 3 is proposed for this factor.

T cell-replacing factor- (TRF) induced IgG secretion in a human B blastoid cell line and demonstration of acceptors for TRF.

Abstract: IgG-secretion was induced in a human B blastoid cell line, CESS, by the addition of partially purified T cell-derived helper factor(s) (TRF), which had been obtained from PHA-stimulated human T cells. The number of IgG-producing cells in CESS cells reached its maximal level (10% of total cells) within 48 hr after the addition of TRF. TRF did not affect the proliferation of CESS cells and the block of cell proliferation with hydroxyurea did not inhibit the increase of IgG-producing cells, showing that TRF induced IgG-production in CESS cells without any requirement of cell division. TRF activity was completely removed by CESS cells but TCGF-activity in the same preparation was not absorbed with CESS cells. On the other hand, TCGF-dependent human killer cells absorbed TCGF activity but not TRF activity in the same preparation. The binding of 125I-labeled factor(s) on CESS cells was also demonstrated. These results showed the presence of acceptors for TRF on the surface of CESS cells and this cell line will provide useful means for the chemical characterization of acceptors and for the study of the mechanisms of the signal transmission through acceptors.

Effect of insulin on growth of cultured human arterial smooth muscle cells.

Abstract: The effect of insulin (10--10 000 mU/1) on the proliferation of cultured human arterial smooth muscle cells was studied. Smooth muscle cells were cultivated by explanation. Cells from the third to the fifth subculture were used. Proliferation was studied by growth curve experiments. Insulin stimulated cell proliferation in all concentrations (p less than 0.001). Growth was however stimulated more by a medium containing 10% fetal calf serum. The highest concentration of insulin produced only 35% of the effect of 10% fetal calf serum. Our results support the hypothesis that insulin may play a role in atherosclerosis.

p53 transformation-related protein: detection by monoclonal antibody in mouse and human cells

Abstract: A transformation-related protein of Mr 53,000, designated p53, has been detected in a range of neoplastic cell types of the mouse by using immunoprecipitation of [35S]-methionine-labeled cell extracts with mouse antiserum [DeLeo, A. B., Jay, G., Appella, E., DuBois, G. C., Law, L. W. & Old, L. J. (1979) Proc. Natl. Acad. Sci. USA 76, 2420-2424]. We have now prepared a monoclonal antibody to p53 and have used it to study the occurrence and intracellular location of p53 by indirect immunofluorescence assays. In accordance with the results of immunoprecipitation, these tests showed p53 in all 13 transformed mouse cell lines studied. In each case, p53 was found in the nucleus. No p53 was detected in normal mouse fibroblasts, 3T3 cells, bone marrow cells, thymus cells, or embryo cells. A serologically related protein was detected in the nucleus of human cells by monoclonal antibody and was found in both normal and neoplastic cultured cells. Expression of p53 in human cells correlates with the growth characteristics of the culture, high p53 levels being associated with rapid cell proliferation and low p53 levels, with cessation of cell division. Normal and malignant human cells differ, however, with regard to the effect of confluency on p53 expression. Normal kidney epithelium and fetal brain cells, which express high p53 levels during exponential growth, show a prompt decrease in p53 associated with contact inhibition of cell division. Malignant cells, on the other hand, continue to express p53 after confluency and subsequent overgrowth of the monolayers. These results suggest that p53 may be involved in the normal regulation of cell division and that malignant transformation leads to abnormalities in the control of p53 expression.

Effects of tunicamycin on B16 metastatic melanoma cell surface glycoproteins and blood-borne arrest and survival properties.

Abstract: The role of cell surface glycoproteins in determining in vivo blood-borne arrest and survival characteristics of murine melanoma sublines of low (B16-F1) or high (B16-F10) potential to form experimental lung metastases after injection iv was assessed after inhibiting tumor cell protein glycosylation with tunicamycin Incubation of B16-F1 or B16-F10 cells with 05 micrograms (or above) tunicamycin per ml for 12 to 36 hr inhibited significantly lung tumor colony formation Examination of B16 cells in the presence of 05 micrograms drug per ml indicated that complex oligosaccharide synthesis was inhibited greater than 90%, while protein synthesis remained at about 50% of the control levels Tunicamycin induced morphological changes in B16-F1 and B16-F10 cells such as cellular rounding Cell growth was also inhibited by tunicamycin These effects were reversible, and B16 cells recovered their normal morphologies and growth rates within 24 hr after removal of the drug Exposed cell surface protein analyzed by lactoperoxidase-catalyzed 125I iodination-sodium dodecyl sulfate-polyacrylamide gel electrophoresis-autoradiography showed few changes after tunicamycin treatment; however, sialogalactoproteins (detected by the binding of 125I-labeled R communis agglutinin I to polyacrylamide gels containing desialized B16 cell surface components) were reduced dramatically by the drug The adhesive properties of untreated and tunicamycin-treated B16 cells were assessed by the binding of 51Cr-labeled B16 cells to endothelial cell monolayers Tunicamycin-treated B16-F1 and B16-F10 cells adhered at lower rates to endothelial cells such that after 24 to 36 hr of drug (05 micrograms/ml) treatment adhesion was almost completely blocked, suggesting that tunicamycin-induced cell surface glycoprotein changes in B16 melanoma cells may interfere with tumor cell-host cell interactions that lead to arrest and survival of blood-borne malignant cells

The production and localization of laminin in cultured vascular and corneal endothelial cells.

Abstract: The production and localization of laminin, as a function of cell density (sparse versus confluent cultures) and growth stage (actively growing versus resting cultures), has been compared on the cell surfaces of cultured vascular and corneal endothelial cells. Comparison of the abilities of the two types of cells to secrete laminin and fibronectin into their incubation medium reveals that vascular endothelial cells can secrete 20-fold as much laminin as can corneal endothelial cells. In contrast, both cell types produce comparable amounts of fibronectin. Furthermore, if one compares the secretion of laminin and fibronectin as a function of cell growth, it appears that the laminin released into the medium by either vascular or corneal endothelial cells, is a function of cell density and cell growth, since this release is most pronounced when the cells are sparse and actively growing, and decreases by 10- and 30-fold, respectively, when either vascular or corneal endothelial cell cultures become confluent. With regard to fibronectin secretion, no such variation can be seen with vascular endothelial cell cultures, regardless of whether they are sparse and actively growing or confluent and resting. Corneal endothelial cell cultures, demonstrated a twofold increase in fibronectin production when they were confluent and resting as compared to when they were sparse and actively growing. When the distribution of laminin versus fibronectin within the apical and basal cell surfaces of cultured corneal and vascular endothelial cells is compared, one can observe that unlike fibronectin, which in sparse and subconfluent cultures can be seen to be associated with both the apical and basal cell surfaces, laminin does not ever seem to be present on the apical cell surface. In confluent cultures, laminin can be found associated primarily with the extracellular matrix beneath the cell monolayer, where it codistributes with type IV collagen.

Cell proliferation and its relationship to clinical features and relapse in breast cancers.

Abstract: The relationship between primary tumor proliferative activity and clinical and pathologic characteristics was analyzed in relation to menopausal status for 541 breast cancer patients. The thymidine-3H labeling index (LI) showed significantly higher median values in cancers from premenopausal (4.2%) and paramenopausal (4.2%) patients in comparison to that of cancers from postmenopausal (1.8%) patients. The LI was not generally correlated to tumor size. The only significant correlation was limited to tumors with negative axillary lymph nodes from premenopausal patients. The proliferative activity of primary tumors was neither correlated to the presence nor the extension of axillary metastasis. The prognostic significance of the primary tumor LI was assessed in 145 untreated patients with cancers without axillary metastases. A higher median value of LI was observed in tumors from patients who relapsed (5.7%) within 52 months than in tumors from those who did not relapse (2%). However, the difference was statistically significant (P less than 0.01) in premenopausal patients, but not in postmenopausal patients. Similarly, a significantly (P less than 0.0005) higher rate of relapse (67.4%) was observed in patients with tumors that had a LI above the median value of 4.6% in comparison to that (0%) of tumors with a LI below the median value in premenopausal patients. No statistically significant relationship was observed between proliferative activity of the primary tumor and risk of relapse in postmenopausal patients.

Differential response to growth factor by rat mammary epithelium plated on different collagen substrata in serum-free medium.

Abstract: Primary cultures of rat mammary epithelial cells proliferate and synthesize basement membrane collagen (type IV collagen) in a serum-free medium supplemented with epidermal growth factor (EGF), hydrocortisone or dexamethasone, insulin, transferrin, and Pedersen fetuin. The growth response of the cells to EGF and glucocorticoids but not to insulin or transferrin varies depending on the substratum on which the cells are plated. Cell growth is 4 times more sensitive to omission of EGF or glucocorticoid on type I collagen or plastic substratum than on type IV collagen substratum. The mechanism by which these two growth factors differentially affect cell growth appears to be linked to an increase in type IV collagen synthesis and a stabilization of secreted type IV collagen in the extracellular matrix. Glucocorticoids suppress the elaboration of type IV collagenolytic activity by the cells whereas EGF stimulates amino acid incorporation into type IV collagen. The results suggest that EGF and glucocorticoids affect mammary epithelial cell growth by facilitating the accumulation of the appropriate cell substratum.

The regulation of growth and differentiation of a murine B cell lymphoma. II. The inhibition of WEHI 231 by anti-immunoglobulin antibodies.

Abstract: WEHI 231 is a murine B cell lymphoma, which from our previous studies is highly susceptible to a lipopolysaccharide (LPS) induced differentiation signal. In this paper we show that anti-immunoglobulin (Ig) antibody at low concentrations (0.1 micrograms/ml) inhibits cell proliferation and results in cell death. Heterologous sera specific for mu- and kappa-chains, and a monoclonal antibody (E4) developed in our laboratory and specific for mu-chain, profoundly suppressed the growth of WEHI 231 in both soft agar culture and liquid culture. The F(ab')2 fragments were as potent as intact Ig, indicating that neither Fc receptor binding nor complement activation were required for this inhibition of growth. Neither heterologous antibodies that bound to WEHI 231 but not to the Ig receptor, nor a monoclonal antibody that bound to non-Ig cell surface structures (a brain-associated antigen) inhibited the growth of WEHI 231. LPS did not prevent inhibition of growth by anti-Ig antibody, and even when addition of LPS preceded the addition of anti-Ig, profound inhibition occurred. WEHI 231 thus promises to be a convenient tool for investigating the mechanism of signal transmission by the Ig receptor.

Induction of differentiation of cultured human and mouse myeloid leukemia cells by alkyl-lysophospholipids.

Abstract: Alkyl-lysophospholipids are synthetic analogs of naturally occurring lysophospholipids. The effects of these compounds on cell proliferation and differentiation of cultured human (HL-60) and mouse (M1) myeloid leukemia cells were studied. Both cell lines were induced to differentiate into morphologically and functionally mature granulocytes and macrophages by incubation with a wide variety of these compounds. Some alkyl-lysophospholipids induced differentiation (judged morphologically and by the appearance of abilities to reduce nitro blue tetrazolium, to phagocytize latex particles, and to induce lysozyme activity) of both the cell lines at concentrations of 1 µg/ml. However, these compounds did not affect colony formation of normal mouse bone marrow cells even at a higher concentration, 20 µg/ml. These results suggest that alkyl-lysophospholipids induce cell differentiation of myeloid leukemia cells without affecting proliferation and differentiation of normal bone marrow cells. Thus, these compounds could be useful in therapy of myeloid leukemia.

Somatomedin: Physiological Control and Effects on Cell Proliferation

Abstract: The pituitary somatotropic hormone has long been believed to be the principal regulator of balanced growth in vivo since growth hormone deficient patients exhibit proportional dwarfism and patients with acromegaly undergo diffuse enlargement of their internal organs and soft tissues Administration of growth hormone to pituitary dwarfs is followed by dramatic increases in both cell number and cell size (Cheek and Hill, 1974) Attempts to develop in vitro bioassays based on the supposed effects of growth hormone, however, made it apparent that the magnitude of the in vitro effects produced by growth hormone correlated poorly with its in vivo actions While searching for an in vitro bioassay system, Salmon and Daughaday (1957) observed that growth hormone itself had no direct effect on cartilage metabolism, but that plasma from normal or growth hormone-treated hypophysectomized rats contained a growth hormone-inducible factor which directly stimulated sulfate uptake by this tissue This serum factor, initially designatedcsul-fation factor,” subsequently was shown to consist of a family of closely related pep-tide growth factors which were given the generic designation “somatomedin” (Daughaday et al, 1972; Hall and Van Wyk, 1974) Although the somatomedins originally were postulated to mediate the anabolic effects of growth hormone only on skeletal tissue, they subsequently have been shown to promote cellular proliferation in a wide variety of cell types (Van Wyk and Underwood, 1978; Zapf et al, 1978 b) These substances now are believed to form a vital link between growth hormone and the stimulation of the metabolic processes leading to cellular proliferation

Binding of 125I-labelled human alpha interferon to human lymphoid cells.

Abstract: To investigate the binding of interferon to human lymphoid cells, we purified human alpha interferon and radio-labelled it with iodine-125. Binding at 4 degrees C could be saturated and was inhibited by unlabelled interferon; it was specific for cells of human origin. Dissociation constants for the complex of interferon and receptor site were of the order 10(-9)-10(-11) M. All human cells tested showed such binding. Occupation of these high-affinity sites, at 37 degrees C, was compared with the inhibition of cellular growth due to interferon. The most sensitive cell line (Daudi) gave a complete biological response with only a fraction of its sites occupied. Evidence of two sites was found for a line (P3HRI) showing intermediate sensitivity. A relatively insensitive line (Raji) showed no response when all its high-affinity sites were occupied.