Inhibition of Glucose Uptake in Lymphosarcoma P1798 by Cortisol and Its Relationship to the Biosynthesis of Deoxyribonucleic Acid

How we approach the perioperative management of patients with chronic lymphocytic leukaemia receiving continuous cancer-directed therapies

Historically, invasive procedures and surgeries were deferred in patients with haematological malignancies including advanced stage chronic lymphocytic leukaemia (CLL) because of limited life expectancy. However, novel, and often continuous, treatments have markedly improved outcomes in CLL. Some patients may expect years of treatment response and disease control, overcoming the short life expectancy that deters interventionalists. Such patients now often undergo various invasive procedures including major surgery. To inform peri-operative management, we summarize the relevant side effects and drug interactions of continuous CLL therapies, highlight potential surgical risks, and provide recommendations on withholding specific CLL drugs around invasive procedures.

N-terminal peptide fragments of lipocortin-1 inhibit A549 cell growth and block EGF-induced stimulation of proliferation

Lipocortin-1 mediates growth inhibition of glucocorticoids in A549 cells by suppressing the release of PGE2 necessary for their proliferation. We now show that 2 peptide fragments derived from the N-terminal portion of lipocortin-1 corresponding to amino-acids 13-25 and 21-33 also inhibited A549 cell growth and suppressed release of PGE2, whereas peptides 1-12 and 13-25 (Phe21; in which the tyrosine at position 21 was replaced by a phenylalanine residue) were inactive. Similarly, peptide 21-33 (Phe21) and a scrambled sequence of 13-25 failed to inhibit cell growth. Moreover, the EGF-induced stimulation of cell proliferation and PGE2 release in these cells was blocked by peptides 13-25 and 21-33, and also by peptides 1-12, 13-25 (Phe21) and 21-33 (Phe21), but not by a scrambled sequence of peptide 13-25.

Isolation and characterization of cortisol-sensitive and -resistant P1798 mouse lymphosarcoma cell lines

Three cell lines have been isolated and characterized from the P1798 mouse lymphosarcoma. One line, derived from a glucocorticoid-resistant tumor, was glucocorticoid-resistant in vitro. The other two cell lines, derived from glucocorticoid-sensitive and -resistant parental tumors, respectively, were shown to be glucocorticoid-sensitive in vitro. The glucocorticoid receptor from all three cell lines bound glucocorticoid with similar affinity and capacity. However, based on Sephacryl S-300 gel filtration, the glucocorticoid receptor from the resistant cell line was smaller than that of the two sensitive cell lines. Moreover, the glucocorticoid receptor from the resistant cell line accumulated to a greater extent in the nucleus. This resistant cell line thus resembles the nti variant of the S49 lymphoma cell line. All three cell lines were tumorigenic and metastatic when reimplanted into mice, contained the normal mouse diploid complement of 40 chromosomes and exhibited the same responsiveness to cortisol in vivo as they did in vitro. It is concluded that the ready passage of these cell lines in vitro or in vivo and the presence of the small receptor in the resistant line should make them excellent model systems for the study of glucocorticoid resistance.

Studies on the age-related decline in the response of lymphoid cells to mitogens: measurements of concanavalin A binding and stimulation of calcium and sugar uptake in thymocytes from rats of varying ages

We have previously demonstrated that mitogenic response of rat thymocytes to concanavalin A (Con A) declines with age (Segal, Troen and Ingbar, Thymus, in press). To elucidate the mechanism underlying this process, we have examined the effect of age on Con A binding and stimulation of calcium and sugar uptake in thymocytes from rats varying in age from 10 to 360 days. Binding of Con A by thymocytes remained unchanged with advancing age. Basal uptake of the glucose analogue 2-[3H]deoxyglucose (2-DG) by rat thymocytes declined with age, becoming significantly lower than maximal values (26 days) at 4 months of age. While the proportionate increase in thymocyte 2-DG uptake produced by Con A remained essentially unchanged. However, because of the decline in basal 2-DG uptake, total uptake of 2-DG in the presence of Con A decreased with age becoming significantly lower than maximal values at 4 months. Basal calcium-45 uptake by thymocytes was practically the same in all the age-groups studied, except at 21 days, where, as with basal 2-DG uptake, it was markedly smaller, But the stimulatory effect of Con A on 45Ca uptake declined progressively with age and was nil at 360 days. From these observations I suggest that the age-related decline in the responsiveness of rat thymocytes to Con A does not result from a change in the binding of Con A by the lymphoid cell, but from, at least in part, a decrease in its cellular stimulation of calcium and sugar uptake.

Binding of the glucocorticoid receptor complex to the nucleosomal core in the P1798 mouse lymphosarcoma

Binding of the glucocorticoid receptor complex to nucleosomes has been studied using the mouse P1798 lymphosarcoma. Cells were incubated with [3H]triamcinolone acetonide (TA), and nuclei prepared and digested with 3 different concentrations of micrococcal nuclease. After fractionation with EDTA and NaCl, it was observed that [3H]TA bound with similar specific radioactivity to mononucleosomes containing both core and linker DNA, of 183 +/- 5, and 168 +/- 4 base pair lengths, respectively, as well as to core size DNA, of 148 +/- 3 base pair length, suggesting that the glucocorticoid receptor bound to the core portion of the nucleosome. Steroid binding was found to be associated with regions of the nucleosome that were depleted in histone H1 and enriched in high mobility group (HMG) proteins 1 and 2; only negligible binding was noted in nucleosomes enriched in histone H1 and depleted in HMG proteins. In addition to binding to core nucleosomes, the glucocorticoid receptor complex was also shown to bind to a fraction sedimenting at 5-6 S on sucrose gradients characterized by subnucleosome and mononucleosome size DNA, as well as by core histones. While binding of the steroid receptor complex to linker regions of the nucleosome cannot be ruled out, this data would appear to present the first concrete evidence that glucocorticoid binding, at least in the P1798 lymphosarcoma, is to core nucleosomes. Some caution in interpretation of the results is indicated, however, on 2 points: (1) receptor redistribution during nuclease digestion cannot be ruled out; (2) only the binding of a small proportion of the steroid receptor complex may be physiologically relevant.

Inhibition of the biosynthesis of deoxyribonucleic acid, ribonucleic acid and protein in HeLa S3 cells by cucurbitacins, glucocorticoid-like cytotoxic triterpenes

Cucurbitacins were found to inhibit the incorporation of radioactive precursors into DNA, RNA and protein in intact and permeabilized HeLa S3 cells. The observed inhibition was rapid and irreversible although the maximal effect (almost complete inhibition) required several hours of cell exposition to the agent. The magnitude of the inhibition was, with some exceptions, nearly the same for all three precursors within the entire range of cucurbitacin concentrations examined. The ID50 values (concentrations required to produce half-maximal inhibition of the macromolecule biosynthesis) determined for several cucurbitacins were very close to their respective ED50 values (those for half-maximal inhibition of cell proliferation). Parallel with the inhibition of [3H]-labelled precursor incorporations into nucleic acids, cucurbitacin diminished the [3H]thymidine and [3H]uridine nucleotides' pool sizes of HeLa S3 cells. No effect of cucurbitacin on the [3H]leucine pool was observed. The studies presented prove that cucurbitacins inhibit the biosynthesis of DNA, RNA and protein in HeLa S3 cells, and that these inhibitory effects are closely related to the inhibition of HeLa S3 cell proliferation by cucurbitacins. The mechanism of the inhibition is unknown but the obtained results suggest that cucurbitacins act upon an unidentified target, which results in the inhibition of macromolecule biosynthesis. It was also found that these inhibitory effects of cucurbitacins are neither mediated by glucocorticoid receptors nor require replication, transcription or translation.

The uncoupling of macromolecular synthesis from cell division in SV3T3 cells by glucocorticoids: the imposition of a G2 block

Through a receptor-mediated process glucocorticosteroids block cell division by 20-45 hours in SV40-transformed 3T3 (SV3T3) mouse fibroblasts growing in a low calf serum (0.30% v/v) medium containing biotin. However, the rate of DNA synthesis, determined at various times after dexamethasone addition by the incorporation of radioactive thymidine into acid-insoluble material, is not inhibited by this steroid as late as 66 hours. A modest decrease is observable by 91 hours. There is also no reduction in the uptake of exogenous thymidine into acid-soluble cellular pools. Similarly, RNA synthesis and the uptake of radioactive uridine are not affected by the glucocorticoid up to 69 hours. Measurements of the amounts of cellular DNA (by the fluorescent dye, 4', 6-diamidino-2-phenylindole) and protein revealed that both macromolecules are present in elevated quantities in steroid-treated cells. (The constancy of the protein content in the nonproliferative stage suggests that protein synthesis and degradation are occurring at equal rates.) If the steroid is removed and fresh 10% calf serum medium added, cell division commences (even if nearly 90% of protein synthesis is inhibited by cycloheximide) as early as 45 minutes later such that by 2 hours the viable cell count increases by as much as 70%. Since the growth curve after recovery resembles a step function, it appears that the cells are partially synchronized by the glucocorticoid. These results demonstrate that the glucocorticoid cytostatic effect in SV3T3 cells is the result of a block not in G1, as previously thought, but in G2.

Cytotoxic effects of dexamethasone restricted to noncycling, early G1-phase cells of L1210 leukemia

The cytostatic and cytolytic effects of dexamethasone were studied as functions of cell cycle position in mouse L1210 leukemia cells. To this end, the cells were separated according to size by sedimentation at unit gravity in a specially designed sedimentation chamber. The fractions were analyzed by radioautography and flow cytophotometry. The size-distributions obtained by 1g sedimentation coincided with cell-cycle age distribution. With increasing fraction number, samples highly enriched in G1, S, and G2/M cells, respectively were obtained: the smallest cells being in early G1 and the largest in mitosis. In the presence of dexamethasone (10(-6)-10(-5) M), growth slowed down after a few cell cycles and the cells accumulated in early G1 phase. Lytic cell kill by continued exposure to the drug was confined to the fractions containing the small, early G1-phase cells. These fractions were also enriched in noncycling cells that were not labeled by prolonged exposure to 3H-thymidine. After removal of dexamethasone, the cells in S and G2/M phase completed cell cycle traverse but were retarded again in the G1 and early S phase of the next division cycle. The data suggest a memory effect for previous drug exposure. It is concluded that the cytostatic and cytolytic effects of dexamethasone are separate, though not unrelated events. Cytolysis is confined to the noncycling cells that in untreated populations can exit from the dividing compartment during a transitional phase of about 60 minutes subsequent to mitotic division. The cytostatic effects potentiate cytolysis by accumulating the cells in the early G1 phase and thus increasing the probability of their transit to the G0 compartment, sensitive for drug-mediated cytolysis.

Insulin and growth factors stimulate rapid posttranslational changes in glucose transport in ovarian granulosa cells

The glucose analogues, 3-O-methyl-D-glucose and 2-deoxy-D-glucose, have been used to characterize glucose transport and its regulation by serum and growth factors in monolayer cultures of granulosa cells obtained from bovine ovaries. Uptake of 3-O-methylglucose was shown to be independent of the Na+-gradient, independent of energy, did not show accelerated exchange, and was stereospecific. Serum withdrawal resulted in a biphasic decrease in initial rates of glucose uptake with half-times for the two phases of 50 minutes and 3 hours. Insulin could prevent the decrease in uptake rates with a half-maximum concentration of 10.0 1/8 3 nM. Insulin was shown to stimulate DNA synthesis with a concentration of half-maximum response of 28 nM. Insulin or serum stimulation of 3-O-methylglucose uptakes in serum-starved cells resulted in a two threefold increase in initial rates, with a time for half-maximum stimulation of 3 minutes. The insulin-stimulated increase was insensitive to cycloheximide and cyanide during the first 30 minutes, and this early, rapid stimulation was also produced by brain FGF (fibroblast growth factor), pituitary FGF, epidermal growth factor, calf serum, and some but not all samples of follicular fluid. Insulin also stimulated 2-deoxyglucose and a-aminoisobutyric acid uptake during the first 5 minutes of addition and these early stimulations were shown to be posttranslational changes.

Cell proliferation and DNA dependent DNA polymerase estimation in acute lymphoblastic leukaemia during treatment with prednisone and vincristine

The presence of DNA polymerase and primer-template DNA in lymphoblast nuclei by measuring the in vitro incorporation of 3H-thymidine-5'-triphosphate (3H-TTP) was studied in 10 patients with acute lymphoblastic leukemia. Protein synthesis and various other cytokinetic parameters were also studied. After prednisone (P) administration a marked decrease in 3H-TTP labelling index (3H-TTP LI) was apparent together with an inhibition of 3H-leucine incorporation (3H-LEU LI) into lymphoblasts. A moderate decrease in 3H-TDR labelling index (3H-TDR LI) and a later decrease in mitotic index (MI) were seen. Single cell DNA measurements showed a depletion of 3H-TDR labelled lymphoblasts in early part of S-phase apparent at 24 h lasting up to 54 h after P administration. Vncristine given as a flash injection later in the study period caused an immediate rise of the MI, at the same time the P induced decline in 3H-TTP LI, 3H-TDR LI and 3H-LEU LI were continued in most patients. P is thought to damage the cells both in and outside the cell cycle. In the cell cycle the effect of P is an arresting effect in G1.

Glucocorticoid activity of various progesterone analogs: correlation between specific binding in thymus and liver and biologic activity

When tested in an in vitro assay system, progesterone and various analogs of this steroid were shown to compete with [3H] triamcinolone acetonide (TA) for specific glucocorticoid receptors in both rat liver and thymus. Of these analogs, the following derivatives of progesterone were potent competitors of TA binding and, when injected into adrenalectomized rats, induced regression of the thymus and marked increases in hepatic tyrosine aminotransferase activity: 11 beta-hydroxyl, 6 alpha-methyl, 6 alpha, 16 alpha-dimethyl, and 6 alpha-methyl-17 alpha-hydroxyl. In contrast, progesterone, 16 alpha-methyl, and 17 alpha-hydroxy progesterone competed with TA in vitro but failed to elicit either gluco- or antiglucocorticoid activity in vivo. Also, we observed that the oral contraceptive 6 alpha-methyl-17-(1-propynyl)testosterone competes very effectively with TA in a cell-free preparation of rat liver and induces an increase in hepatic tyrosine aminotransferase activity. The 11 beta-hydroxyl group has previously been thought to be essential for glucocorticoid activity. Our studies indicate that substitution of progesterone or testosterone with a 6 alpha-methyl group negates the need for an 11 beta-hydroxyl substitutuent as a prerequisite for glucocorticoid activity.

Effect of cortisol on the ultrastructure of normal, leukemic, and cultured human lymphocytes

The effect of cortisol on the ultrastructure of normal, leukemic, and cultured human lymphocytes during a 2-hr incubation was investigated. The presence of 10(-5) M cortisol in the incubation medium produced in normal lymphocytes a variety of alterations in cytoplasmic organelles. Mitochondria were most affected and showed evidence of irreversible deterioration (formation of myelin figures). Occasional cells demonstrated an overt rearrangement of their cytoplasmic membranes resulting in a bizarre array of parallel cisternae-like structures. More commonly, the usually underdeveloped Golgi of normal lymphocytes became very pronounced in structure. All of these alterations were produced within 2 hr of incubation, but only in normal human lymphocytes. Under identical conditions, no evidence of ultrastructural changes were produced by cortisol in either lymphocytes from chronic lymphocytic leukemic patients, or those from the RPMI 1788 cell line.