Effect of vitamin D3 and 1,25(OH)2D3 on growth of neoplastically derived cell lines and their alkaline phosphatase activity.

Inhibitory effects of 1,25(OH)2D3 and D3 on growth of four neoplastically derived cells were observed in human acute leukemia cell culture CEM-C-1 and CEM-C-7, human cervical carcinoma cell lines C-4-1 and human epithelioid carcinoma cells of cervix HeLa S3K. Concurrently, in dexamethasone-responsive cells C-4-1 and HeLa S3K there was a 1,25(OH)2D3 and D3 induced elevation of alkaline phosphatase with 1,25(OH)2D3 showing the greater effects. It is supposed that vitamins D3-induced alkaline phosphatase activity in malignant cells, which is proposed to be a possible marker of cell differentiation, can be associated with the membrane effects of these vitamins.

Mechanism of farnesol cytotoxicity: further evidence for the role of PKC-dependent signal transduction in farnesol-induced apoptotic cell death.

Mechanism of the inhibitory effect of isoprenoid farnesol on cell proliferation has been studied in human acute leukemia CEM-C1 cells. Farnesol (20 microM) reduced the rate of radioactive label incorporation into cellular diacylglycerol (DAG) and phosphocholine, the products of degradation of phosphatidylcholine (PC), indicating inhibition of PC-specific phospholipase C after about 1 h of incubation. Inhibition of phospholipase D by farnesol at the later incubation time (about 2 h) was demonstrated by a decrease in synthesis of PC-derived phosphatidylethanol in the presence of ethanol.

Selective farnesol toxicity and translocation of protein kinase C in neoplastic HeLa-S3K and non-neoplastic CF-3 cells.

We have reported earlier that farnesol, a 15 carbon isoprenoid, has inhibitory effects on the growth and viability of a variety of cultured cells of neoplastic derivation but is considerably less cytotoxic to cells derived from normal tissue (Cancer Lett., 79, 175-179). As part of our search for the mechanism of this observation, we have studied the effect of 20 microM farnesol on the distribution of protein kinase C (PKC) between cytosolic and membrane fractions of HeLa S3K cells and fibroblasts line CF-3.

Effects of farnesol on the thermotropic behavior of dimyristoylphosphatidylcholine.

Differential scanning calorimetry (DSC) and DPH fluorescence anisotropy have been used to investigate the effects of trans-trans farnesol on the physical properties of model membranes and extracted cell lipids. Farnesol was shown to have a significant effect on the gel to liquid-crystal phase transition temperature, the enthalpy of the transition and the transition co-operativity for extruded vesicles of dimyristoylphosphatidylcholine (DMPC). The phase transition of DMPC vesicles was eliminated at 25 mol% farnesol.

Directed cell killing (apoptosis) in human lymphoblastoid cells incubated in the presence of farnesol: effect of phosphatidylcholine.

Previously reported observations have shown that trans-trans farnesol inhibits incorporation of choline into phosphatidylcholine and reduces the growth rate of the human acute leukemia CEM-C1 cell line (Melnykovych, G., Haug, J.S.

Differences in sensitivity to farnesol toxicity between neoplastically- and non-neoplastically-derived cells in culture.

Six neoplastically-derived cell lines and three cell lines derived from normal tissues were compared for their sensitivity to isoprenoid trans-trans farnesol. Assays of cell numbers and of protein concentrations per culture revealed greater sensitivity of neoplastic cells than of the normal cells. Similar differences were obtained from the comparison of incorporation of [methyl-3H]choline into cellular lipids, with neoplastic cells showing greater inhibition than normal cells.

Farnesol inhibits phosphatidylcholine biosynthesis in cultured cells by decreasing cholinephosphotransferase activity.

The mechanism of inhibition of phosphatidylcholine (PC) biosynthesis by the isoprenoid farnesol was investigated in the human leukaemic CEM-C1 cell line. Cells were preincubated with 20 microM farnesol for up to 2 h and pulsed with [3H]choline. PC biosynthesis was inhibited to one-quarter at the step catalysed by cholinephosphotransferase (CPT).

Growth inhibition of leukemia cell line CEM-C1 by farnesol: effects of phosphatidylcholine and diacylglycerol.

Acute leukemia cells of the established line CEM-C1 were treated during growth in serum-free medium with various concentrations of trans-trans farnesol. At concentrations ranging from 9.0 to 31.

Protein-linked isoprenoid lipids in dexamethasone-treated human lymphoid lines in culture.

Accumulation of isoprenoids was studied in two cell lines derived from acute T-cell leukemia: CEM-C7 cells, whose growth is inhibited by the glucocorticoid dexamethasone, and CEM-C1 cells, which are resistant to this steroid. Isoprenoids were measured by growing the cells in serum-free medium in the presence of lovastatin, which blocks synthesis of mevalonate, and then labeling with exogenous [3H]mevalonolactone. In both cell lines, isoprenoids associated with proteins were detected in cytoplasm, nucleus, and chromatin, and in the chromatin residue that remains after extraction of histone and nonhistone proteins.

Alkyllysophospholipid influenced melanoma cell morphology is associated with decreased attachment to basement membrane.

The alkyllysophospholipid analog 1-0-octadecyl-2-0-methyl-3-phosphorylcholine (ET-18-OCH3) was examined for possible anti attachment effects on B16-F10 murine melanoma cells in vitro. At sub-lethal lipid concentrations B16-F10 cells were inhibited from attaching to reconstituted basement membrane (Matrigel) during a 45 min assay. This type of inhibition was also imparted by the isoprenoid farnesol but not by egg lysophosphatidylcholine (LPC) at concentrations up to 10 micrograms/ml.

Effects of compound RU38486 on growth and lipid biosynthesis in glucocorticoid sensitive human leukemia line CEM-C7.

Glucocorticoid sensitive human lymphoblastoid cells CEM-C7 were examined for the effects of antiglucocorticoid RU38486 on the prevention of early dexamethasone-induced changes, including reduced cell growth, cell shrinkage and fragmentation, decrease in cell plating efficiency and incorporation of acetate into cellular lipids. When RU38486 was added no later than 24 hours after the addition of dexamethasone, it prevented the inhibition of [14C]acetate incorporation into nonsaponifiable lipids, partly reversed the decrease in plating efficiency and reduced cell fragmentation. In addition, the accumulation of dolichols in the nuclei of dexamethasone-treated cells was abolished by RU38486.

Corticosteroid effects on lipid lateral diffusion in CEM-C1 and CEM-C7 acute lymphoblastic leukemia cells.

We have examined glucocorticoid effects on CEM-C7 and CEM-C1 subclones of a leukemic human T-cell line using fluorescence photobleaching recovery techniques. Incubation with 10(-5) M triamcinolone acetonide (TA) increased lipid lateral diffusion on steroid-sensitive CEM-C7 cells but had no effect on steroid-resistant CEM-C1 cells. CEM-C7 cells incubated in serum-free medium responded only to TA but, when fetal calf serum was added to the incubation medium, would also respond to 10(-5) M dexamethasone and hydrocortisone.

Apoptosis: mode of cell death induced in T cell leukemia lines by dexamethasone and other agents.

Glucocorticoids can mediate the destruction of thymocytes and T cell-derived leukemia cells through a mechanism known as apoptosis. The characteristic feature of apoptosis is fragmentation of DNA at internucleosomal linkers through the activity of a specific endonuclease. In this study, an attempt was made to compare dexamethasone-induced apoptosis in two T cell-derived human leukemia lines (CEM-C1 and CEM-C7) to the cell killing brought about by selected cytotoxic agents.

Growth effects of regulatory peptides on human pancreatic cancer lines PANC-1 and MIA PaCa-2.

Several studies have reported effects of gastrointestinal regulatory peptides on growth of experimentally induced pancreatic neoplasms and human cancer cell lines. The growth of human pancreatic cancer lines PANC-1 and MIA PaCa-2 was characterized in vitro, and the effects of cholecystokinin, bombesin, insulin, epidermal growth factor, secretin, vasoactive intestinal peptide, and somatostatin were determined. Fetal bovine serum was required for initiation of growth in both cell lines.

Dexamethasone-induced killing of neoplastic cells of lymphoid derivation: lack of early calcium involvement.

The role of calcium influx in dexamethasone-induced fragmentation of DNA was studied in the glucocorticoid-sensitive human lymphoid line of T cell derivation (CEM-C7). Reduction of calcium content in the medium or the use of EGTA increased DNA fragmentation and appeared to slightly enhance the effect of dexamethasone. Incubation of isolated nuclei in the presence of high concentrations of calcium did not bring about significant DNA fragmentation.

Increased dolichol content in glucocorticoid-sensitive human T-cell leukemia line grown in the presence of dexamethasone.

Two cell lines, derived from human T-cell acute leukemia, one glucocorticoid sensitive (CEM-C7) and the other glucocorticoid resistant (CEM-C1) were grown in the presence of 1 x 10-7 M dexamethasone and were analyzed for their dolichol content. After 24 hrs of incubation, dolichols became significantly elevated in the sensitive but not in the resistant line. Lovastatin, the specific inhibitor of cholesterol synthesis did not affect dolichol levels in either of the two cell lines.

Comparison of dexamethasone and lovastatin (mevinolin) as growth inhibitors in cultures of T-cell derived human acute leukemia lines (CEM).

Because previous studies have shown that a reduction of cholesterol synthesis is one of the earliest effects of dexamethasone on neoplastic lymphoid cells, a study was made to compare dexamethasone to lovastatin, a specific inhibitor of cholesterol synthesis, which acts on 3-hydroxy-3-methylglutaryl coenzyme A reductase. Two cell lines were used, both derived from human acute T-cell leukemia, one dexamethasone-sensitive (CEM-C7), the other dexamethasone-resistant (CEM-Cl). The results revealed a similar pattern of resistance and sensitivity of both lines to lovastatin, although only the dexamethasone effect was reversed by 1 microM RU 486, the antiglucocorticoid steroid.

Defective utilization of cholesterol esters from low-density lipoprotein in a human acute lymphoblastic leukemia T cell line.

The glucocorticoid sensitive CEM-C7 T cell line was derived from human acute lymphoblastic leukemia cells by Norman and Thompson (Cancer Res. 37 (1977) 3875). Madden et al.

The role of cholesterol in the glucocorticoid-mediated inhibition of cell cycle progression in human acute lymphoblastic leukemia cells.

Two glucocorticoid receptor-containing clones of human acute lymphoblastic leukemia, one (CEM-C7) sensitive and one (CEM-C1) resistant to dexamethasone (dex) were studied in an effort to identify the time course of the biochemical changes responsible for dex-induced growth inhibition of CEM-C7 cells. Cells were synchronized by treatment with 0.25 mM (C7) or 0.

Differential regulation of the synthesis of mannosylphosphoryl derivatives of dolichol and retinol in HeLa cells.

We have shown earlier that in HeLa S3G cells, glucocorticoids stimulate the synthesis of dolichyl phosphorylmannose (Dol-P-Man) with a concomitant increase in the glycosylation of proteins (Ramachandran, C.K., Gray, S.

Enhancement in the adhesion of tumor cells to endothelial cells by decreased cholesterol synthesis.

Adhesive interactions between tumor cells and the endothelial cells are presumed to be an obligatory step in the metastatic process. Using an in vitro model, we have examined the role of endothelial lipids in the regulation of this interaction. The cholesterol levels of bovine aorta endothelial cell monolayers were inhibited by the addition of compactin, 25-hydroxycholesterol, or 7-ketocholesterol.

Elevation of alkaline phosphatase by retinol in bovine endothelial cells and its possible relationship to lipid biosynthesis.

Alkaline phosphatase (EC 3.1.3.

Possible role of cholesterol in the susceptibility of a human acute lymphoblastic leukemia cell line to dexamethasone.

Because the absence of high affinity glucocorticoid receptors in lymphoid leukemia cells does not always correlate with the resistance to glucocorticoids in vitro, an effort was made to identify an alternate biochemical marker which, independently from the receptor system, would improve the reliability of the existing in vitro sensitivity assays as predictors of the patients' response to glucocorticoid therapy. Two receptor-containing lines of acute lymphoblastic leukemia, one glucocorticoid sensitive (CEM-C7) and one glucocorticoid resistant (CEM-C1), were used to study endogenous synthesis of cholesterol with [14C]-acetate as a cholesterol precursor. We found that dexamethasone inhibited cholesterol synthesis in the glucocorticoid-sensitive clone but was without effect on the resistant clone.

Synergistic stimulation of alkaline phosphatase activity in bovine aortic endothelial cells grown in the presence of retinoids and glucocorticoids.

Low concentrations of retinol (10 nM-10 microM) and dexamethasone (0.1 nM-1.0 microM) elevated activity of alkaline phosphatase (E.

Regulation of cholesterol biosynthesis and esterification by 25-hydroxycholesterol in a macrophage-like cell line: uncoupling by progesterone.

The coordinated control of cholesterol biosynthesis and esterification by 25-hydroxycholesterol was studied in the macrophage-like cell line P388D1. Since 25-hydroxycholesterol rapidly stimulated incorporation of [3H]oleate into the cholesteryl ester fraction of these cells, we have tested the possibility that the well-known inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) by 25-hydroxycholesterol might be the indirect consequence of an increased cholesterol esterification rather than a direct effect on HMG-CoA reductase. The experimental results show that progesterone, an inhibitor of acyl-CoA:cholesterol acyltransferase (ACAT), when added together with 25-hydroxycholesterol, abolished the increased cholesterol esterification without affecting the inhibition of HMG-CoA reductase by 25-hydroxycholesterol.