scholarly journals Cholesterol and mevalonic acid are independent requirements for the in vitro proliferation of human bone marrow granulocyte progenitor cells: studies using ML-236B

Blood ◽  
1983 ◽  
Vol 61 (4) ◽  
pp. 667-671
Author(s):  
PC Hoffman ◽  
CM Richman ◽  
RA Larson ◽  
S Yachnin
Keyword(s):  
Bone Marrow ◽  
Dna Synthesis ◽  
Colony Formation ◽  
Mononuclear Cells ◽  
Cholesterol Biosynthesis ◽  
Mevalonic Acid ◽  
Human Bone ◽  
Hmg Coa Reductase ◽  
Coa Reductase

ML-236B is a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, the key regulatory enzyme in the sequence that catalyzes the conversion of acetate to mevalonic acid in cholesterol biosynthesis. This compound caused marked inhibition of human bone marrow granulocyte progenitor cell (CFU-C) proliferation, the 50% inhibitory concentration (IHD50) being 2.0 X 10(6)M. Inhibition of colony formation was reversed by mevalonic acid but not by cholesterol. ML-236B also inhibited DNA synthesis and acetate incorporation into cholesterol in marrow mononuclear cells (IHD50 = 5.6 x 10(6)M and 3.2 x 10(7)M, respectively). No inhibition of mevalonate incorporation into cholesterol was observed. These results differ from those observed with 25-hydroxycholesterol, another inhibitor of HMG CoA reductase. The latter compound also inhibited CFU-C proliferation and cholesterol biosynthesis from acetate; inhibition of colony formation was reversed by cholesterol but not by mevalonic acid. In addition, 25- hydroxycholesterol inhibited cholesterol synthesis from mevalonic acid precursor. We conclude that: (1) ML-236B is a potent inhibitor of CFU-C proliferation, DNA synthesis, and cholesterol biosynthesis from acetate precursor in marrow mononuclear cells; (2) the effects of ML-236B are completely reversed by mevalonic acid but not by cholesterol, suggesting that mevalonic acid per se or one or more of its nonsterol products are critical for cell growth; (3) the inhibitory effects of 25- hydroxycholesterol on CFU-C proliferation and cholesterol biosynthesis are not solely a result of its inhibition of HMG CoA reductase, but are due in part to inhibition of enzymatic steps distal to mevalonic acid in the sterol synthetic pathway; and (4) mevalonic acid and cholesterol are independent requirements for CFU-C proliferation and differentiation in vitro.

scholarly journals Cholesterol and mevalonic acid are independent requirements for the in vitro proliferation of human bone marrow granulocyte progenitor cells: studies using ML-236B

Blood ◽  
1983 ◽  
Vol 61 (4) ◽  
pp. 667-671 ◽  
Author(s):  
PC Hoffman ◽  
CM Richman ◽  
RA Larson ◽  
S Yachnin
Keyword(s):  
Bone Marrow ◽  
Dna Synthesis ◽  
Colony Formation ◽  
Mononuclear Cells ◽  
Cholesterol Biosynthesis ◽  
Mevalonic Acid ◽  
Human Bone ◽  
Hmg Coa Reductase ◽  
Coa Reductase

Abstract ML-236B is a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, the key regulatory enzyme in the sequence that catalyzes the conversion of acetate to mevalonic acid in cholesterol biosynthesis. This compound caused marked inhibition of human bone marrow granulocyte progenitor cell (CFU-C) proliferation, the 50% inhibitory concentration (IHD50) being 2.0 X 10(6)M. Inhibition of colony formation was reversed by mevalonic acid but not by cholesterol. ML-236B also inhibited DNA synthesis and acetate incorporation into cholesterol in marrow mononuclear cells (IHD50 = 5.6 x 10(6)M and 3.2 x 10(7)M, respectively). No inhibition of mevalonate incorporation into cholesterol was observed. These results differ from those observed with 25-hydroxycholesterol, another inhibitor of HMG CoA reductase. The latter compound also inhibited CFU-C proliferation and cholesterol biosynthesis from acetate; inhibition of colony formation was reversed by cholesterol but not by mevalonic acid. In addition, 25- hydroxycholesterol inhibited cholesterol synthesis from mevalonic acid precursor. We conclude that: (1) ML-236B is a potent inhibitor of CFU-C proliferation, DNA synthesis, and cholesterol biosynthesis from acetate precursor in marrow mononuclear cells; (2) the effects of ML-236B are completely reversed by mevalonic acid but not by cholesterol, suggesting that mevalonic acid per se or one or more of its nonsterol products are critical for cell growth; (3) the inhibitory effects of 25- hydroxycholesterol on CFU-C proliferation and cholesterol biosynthesis are not solely a result of its inhibition of HMG CoA reductase, but are due in part to inhibition of enzymatic steps distal to mevalonic acid in the sterol synthetic pathway; and (4) mevalonic acid and cholesterol are independent requirements for CFU-C proliferation and differentiation in vitro.

scholarly journals Effect of oxygenated sterol compounds on human bone marrow granulocytic progenitor cells

Blood ◽  
1981 ◽  
Vol 57 (1) ◽  
pp. 164-169 ◽  
Author(s):  
PC Hoffman ◽  
CM Richman ◽  
RC Hsu ◽  
J Chung ◽  
AM Scanu ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Dna Synthesis ◽  
Progenitor Cells ◽  
Mammalian Cells ◽  
Mononuclear Cells ◽  
Potent Inhibitor ◽  
Mevalonic Acid ◽  
Sterol Synthesis ◽  
Marked Inhibition

Abstract Oxygenated sterol compounds are potent inhibitors of sterol and DNA synthesis in mammalian cells. We studied the effects of oxygenated sterols on human marrow granulocytic progenitor cells in vitro (CFU-C). 25-Hydroxycholesterol was found to be a potent inhibitor of sterol synthesis in marrow mononuclear cells, with 50% inhibition occurring at approximately 10(-7) M. This compound, as well as 6-ketocholestanol, 7- ketocholesterol, and 20 alpha-hydroxycholesterol, also demonstrated marked inhibition of CFU-C proliferation. The latter effect, which was not a result of direct cytoxicity of the compounds, was reversible by cholesterol, but not by mevalonic acid. We conclude that inhibition of sterol synthesis by oxygenated sterol compounds may be insufficient to explain their suppression of CFU-C proliferation.

scholarly journals Characterization of the potentiation effect of activin on human erythroid colony formation in vitro

Blood ◽  
1989 ◽  
Vol 73 (4) ◽  
pp. 952-960 ◽  
Author(s):  
J Yu ◽  
L Shao ◽  
J Vaughan ◽  
W Vale ◽  
AL Yu
Keyword(s):  
Bone Marrow ◽  
T Lymphocytes ◽  
Dna Synthesis ◽  
Peripheral Blood ◽  
Colony Formation ◽  
Mononuclear Cells ◽  
Erythroid Progenitors ◽  
Potentiation Effect ◽  
Proliferation And Differentiation

Activin, also named FSH-releasing protein, was previously shown to induce hemoglobin accumulation in K562 cells and potentiate the proliferation and differentiation of CFU-E in human bone marrow cultures. Present studies indicate that the potentiation effect of activin is lineage specific. In addition to CFU-E, activin caused an increase in the colony formation of BFU-E from either bone marrow or peripheral blood. It had little effect on the colony formation of CFU- GM and the mixed colonies from CFU-GEMM. In serum-depleted culture, the effect of activin was shown to be dose-dependent with doses effective at picomolar concentrations. The potentiation effect of activin was exerted indirectly through mediation of both monocytes and T lymphocytes. Activin was also found to increase specifically the proportion of DNA-synthesizing erythroid progenitors from both bone marrow and peripheral blood. It had little effect on DNA synthesis in CFU-GM and in mitogen-stimulated lymphocytes. Addition of the monocytes or T lymphocytes to their respective depleted subpopulations of mononuclear cells reconstituted the enhancing effect of activin on the colony formation and DNA synthesis of erythroid progenitors. These results strongly suggest a specific role of activin in potentiating the proliferation and differentiation of erythroid progenitors in vitro.

scholarly journals Effect of oxygenated sterol compounds on human bone marrow granulocytic progenitor cells

Blood ◽  
1981 ◽  
Vol 57 (1) ◽  
pp. 164-169
Author(s):  
PC Hoffman ◽  
CM Richman ◽  
RC Hsu ◽  
J Chung ◽  
AM Scanu ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Dna Synthesis ◽  
Progenitor Cells ◽  
Mammalian Cells ◽  
Mononuclear Cells ◽  
Potent Inhibitor ◽  
Mevalonic Acid ◽  
Sterol Synthesis ◽  
Marked Inhibition

Oxygenated sterol compounds are potent inhibitors of sterol and DNA synthesis in mammalian cells. We studied the effects of oxygenated sterols on human marrow granulocytic progenitor cells in vitro (CFU-C). 25-Hydroxycholesterol was found to be a potent inhibitor of sterol synthesis in marrow mononuclear cells, with 50% inhibition occurring at approximately 10(-7) M. This compound, as well as 6-ketocholestanol, 7- ketocholesterol, and 20 alpha-hydroxycholesterol, also demonstrated marked inhibition of CFU-C proliferation. The latter effect, which was not a result of direct cytoxicity of the compounds, was reversible by cholesterol, but not by mevalonic acid. We conclude that inhibition of sterol synthesis by oxygenated sterol compounds may be insufficient to explain their suppression of CFU-C proliferation.

scholarly journals Characterization of the potentiation effect of activin on human erythroid colony formation in vitro

Blood ◽  
1989 ◽  
Vol 73 (4) ◽  
pp. 952-960 ◽  
Author(s):  
J Yu ◽  
L Shao ◽  
J Vaughan ◽  
W Vale ◽  
AL Yu
Keyword(s):  
Bone Marrow ◽  
T Lymphocytes ◽  
Dna Synthesis ◽  
Peripheral Blood ◽  
Colony Formation ◽  
Mononuclear Cells ◽  
Erythroid Progenitors ◽  
Potentiation Effect ◽  
Proliferation And Differentiation

Abstract Activin, also named FSH-releasing protein, was previously shown to induce hemoglobin accumulation in K562 cells and potentiate the proliferation and differentiation of CFU-E in human bone marrow cultures. Present studies indicate that the potentiation effect of activin is lineage specific. In addition to CFU-E, activin caused an increase in the colony formation of BFU-E from either bone marrow or peripheral blood. It had little effect on the colony formation of CFU- GM and the mixed colonies from CFU-GEMM. In serum-depleted culture, the effect of activin was shown to be dose-dependent with doses effective at picomolar concentrations. The potentiation effect of activin was exerted indirectly through mediation of both monocytes and T lymphocytes. Activin was also found to increase specifically the proportion of DNA-synthesizing erythroid progenitors from both bone marrow and peripheral blood. It had little effect on DNA synthesis in CFU-GM and in mitogen-stimulated lymphocytes. Addition of the monocytes or T lymphocytes to their respective depleted subpopulations of mononuclear cells reconstituted the enhancing effect of activin on the colony formation and DNA synthesis of erythroid progenitors. These results strongly suggest a specific role of activin in potentiating the proliferation and differentiation of erythroid progenitors in vitro.

scholarly journals Regulation of hepatic cholesterol biosynthesis. Effects of a cytochrome P-450 inhibitor on the formation and metabolism of oxygenated sterol products of lanosterol

1989 ◽  
Vol 264 (2) ◽  
pp. 495-502 ◽  
Author(s):  
J Iglesias ◽  
G F Gibbons
Keyword(s):  
Reductase Activity ◽  
Cholesterol Biosynthesis ◽  
Mevalonic Acid ◽  
Subcellular Fractions ◽  
Hmg Coa Reductase ◽  
Hepatocyte Cultures ◽  
C 32 ◽  
Lanosterol Demethylase ◽  
Cholesterol Precursor ◽  
Coa Reductase

The involvement of oxygenated cholesterol precursors in the regulation of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase activity was studied by examining the effect of ketoconazole on the metabolism of mevalonic acid, lanosterol and the lanosterol metabolites, lanost-8-ene-3 beta,32-diol,3 beta-hydroxylanost-8-en-32-al and 4,4-dimethylcholesta-8,14-dien-3 beta-ol, in liver subcellular fractions and hepatocyte cultures. Inhibition of cholesterol synthesis from mevalonate by ketoconazole at concentrations up to 30 microM was due exclusively to a suppression of cytochrome P-450LDM (LDM = lanosterol demethylase) activity, resulting in a decreased rate of lanosterol 14 alpha-demethylation. No enzyme after the 14 alpha-demethylase step was affected. When [14C]mevalonate was the cholesterol precursor, inhibition of cytochrome P450LDM was accompanied by the accumulation of several labelled oxygenated sterols, quantitatively the most important of which was the C-32 aldehyde derivative of lanosterol. There was no accumulation of the 24,25-oxide derivative of lanosterol, nor of the C-32 alcohol. Under these conditions the activity of HMG-CoA reductase declined. The C-32 aldehyde accumulated to a far greater extent when lanost-8-ene-3 beta,32-diol rather than mevalonate was used as the cholesterol precursor in the presence of ketoconazole. With both precursors, this accumulation was reversed at higher concentrations of ketoconazole in liver subcellular fractions. A similar reversal was not observed in hepatocyte cultures.

scholarly journals Enhancement of in vitro beta-thalassemic and normal hematopoiesis by a noncytotoxic monoclonal antibody, 9.1C3: evidence for negative regulation of hematopoiesis by monocytes and natural killer cells

Blood ◽  
1988 ◽  
Vol 72 (4) ◽  
pp. 1124-1133
Author(s):  
G Kannourakis ◽  
GR Johnson ◽  
CG Begley ◽  
JA Werkmeister ◽  
GF Burns
Keyword(s):  
Monoclonal Antibody ◽  
Bone Marrow ◽  
Natural Killer Cells ◽  
Natural Killer ◽  
Colony Formation ◽  
Mononuclear Cells ◽  
Regulatory Control ◽  
Beta Thalassemia ◽  
Killer Cells

The enhancement of in vitro human hematopoiesis by the addition of a noncytotoxic monoclonal antibody, 9.1C3, is described. Enhancement of all aspects of in vitro hematopoiesis was observed on addition of 9.1C3 antibody to cultures of mononuclear cells from normal bone marrow, cord blood, and peripheral blood from beta-thalassemia major patients. In cultures with no exogenous colony-stimulating factor (CSF), the addition of 9.1C3 resulted in a two- to eightfold increase in nonerythroid colony formation. Similarly, for cultures maximally stimulated with CSF, the addition of 9.1C3 antibody resulted in a one- to fourfold increase in colony formation. These effects were abrogated by the removal of either adherent, Leu-M3+ or Leu-7+ cells. Colony- forming cells were shown to be present among the 9.1C3-negative cells when mononuclear cells were sorted by flow cytometry. Media conditioned in the presence of 9.1C3 and mononuclear cells were able to enhance colony formation in vitro for normal nonadherent bone marrow cells beyond that achieved with supramaximal amounts of human placental- conditioned medium and erythropoietin. The data suggest that natural killer cells interact with monocytes to exert a negative regulatory control on in vitro granulopoiesis and erythropoiesis. Consequently, the number of progenitor and multipotential cells in cultures of unfractionated cell populations may be greatly underestimated.

Sign in / Sign up

Export Citation Format

Share Document