Cyclic AMP-dependent protein kinase isoenzymes in human myeloid leukemia (HL60) and breast tumor (MCF-7) cells.

Combinations of retinoic acid (RA) and cAMP mediate many biological responses in a large variety of cell types. While the basis for the apparent synergistic effects of RA and cAMP are not clearly defined, it is likely that activation of PKA by cAMP is involved. However, literature reports concerning the identity of PKA isoforms in HL60 and MCF-7 cells are conflicting.

Potentiation of retinoic acid-induced differentiation of human acute promyelocytic leukemia NB4 cells by butyric acid, tributyrin, and hexamethylene bisacetamide.

Cytodifferentiation therapy by all-trans-retinoic acid (RA) for acute promyelocytic leukemia patients is encouraging in spite of several limitations preventing better clinical outcomes. Most patients in complete remission induced by RA experience relapse and resist further treatment with RA. This resistance primarily is due to a systemic self-induced catabolism of RA, which interferes with the maintenance of effective plasma levels of RA.

Effects of prostaglandin E2 and all-trans retinoic acid combination on induced differentiation of human acute promyelocytic leukemia NB4 cells.

Objective: A human promyelocytic leukemia (APL) cell line NB4 was used to demonstrate the synergistic effects between all-trans retinoic acid (ATRA) and prostaglandin E2 (PGE2) on growth inhibition and cytodifferentiation induction.

Methods: NB4 cells were cultured in the presence of either ATRA or PGE2 as a single agent or in combinations at various ratio. Cell growth was measured and myeloid differentiation was tested on consecutive days over the whole course of culture.

Conformationally defined retinoic acid analogues. 4. Potential new agents for acute promyelocytic and juvenile myelomonocytic leukemias.

We recently synthesized several conformationally constrained retinoic acid (RA) analogues [8-(2'-cyclohexen-1'-ylidene)-3, 7-dimethyl-2,4,6-octatrienoic acids with different alkyl substituents at 2' (R1) and 3' (R2) positions on the cyclohexene ring] (Muccio et al. J. Med.

Decreased retinoylation in NIH 3T3 cells transformed with activated Ha-ras.

Retinoylation (retinoic acid acylation) is a post-translation modification of proteins occurring in a variety of mammalian cell lines and in vivo. To gain further knowledge of the role of retinoylation we studied it in NIH 3T3 cells and NIH 3T3 cells transformed by an activated Ha-ras oncogene (NIH Ha-ras-3T3 cells). In serum-free medium retinoic acid (RA) inhibited growth of NIH 3T3 cells but did not inhibit growth of NIH Ha-ras-3T3 cells.

N-4-hydroxyphenylretinamide enhances retinoic acid-induced differentiation and retinoylation of proteins in the human acute promyelocytic leukemia cell line, NB4, by a mechanism that may involve inhibition of retinoic acid catabolism.

All-trans-retinoic acid (RA) induces differentiation of acute promyelocytic leukemia cells both in vitro and in vivo and is an alternative to cytotoxic chemotherapy in the treatment of acute promyelocytic leukemia. However, despite a complete remission rate of about 90%, most patients relapse and are resistant to further treatment with RA. This resistance primarily is due to an increased systemic catabolism of RA.

Growth, differentiation, and death of retinoic acid-treated human acute promyelocytic leukemia NB4 cells.

Published reports vary markedly on some characteristics of retinoic acid (RA) effects on cell growth and differentiation of the human acute promyelocytic leukemia cell line NB4. We explored possible reasons for this variability and found that the initial cell density of the experimental culture and the stage of growth of the cells used to inoculate experimental cultures were critical parameters for obtaining reproducible growth and differentiation responses of NB4 cells. Thus, the time to reach 50% differentiation in the presence of 1 microM RA and various initial concentrations of cells was 1.

Tunicamycin in combination with retinoic acid synergistically inhibits cell growth while decreasing palmitoylation and enhancing retinoylation of proteins in the human breast cancer cell line MCF-7.

All-trans-Retinoic acid (RA) induces differentiation and inhibits growth of many tumor types. Whereas the RA nuclear receptors mediate genomic effects of RA, there also are many nongenomic effects that do not have defined mechanisms. Some nongenomic effects of RA may involve retinoylation (RA acylation), a posttranslational modification of proteins occurring in many eukaryotic cell lines including the human breast cancer cell line MCF-7.

Retinoylation of proteins in rat liver, kidney, and lung in vivo.

Retinoylation (retinoic acylation) is a posttranslational modification of proteins occurring in a variety of cell types in vitro. This study was done to examine whether retinoylation occurs in vivo. We found that in retinol-deficient rats, radiolabeled retinol or retinoic acid was incorporated into the liver, kidney, and lung in a form that was not removed by extraction with CHCl3:CH3OH.

N-(4-hydroxyphenyl)retinamide (Fenretinide) in combination with retinoic acid enhances differentiation and retinoylation of proteins.

The synthetic retinoid, N-(4-hydroxyphenyl)retinamide (4-HPR; Fenretinide), is a cancer chemopreventive and antiproliferative agent whose mechanism of action is unknown. 4-HPR alone is a poor inducer of differentiation of HL-60 cells compared to all-trans-retinoic acid (RA). Here, we found that combinations of 4-HPR and RA synergistically induced differentiation of HL-60 cells.

Induction of differentiation and covalent binding to proteins by the synthetic retinoids Ch55 and Am80.

all-trans-Retinoic acid (RA) is a potent inducer in vitro of the differentiation of the human acute myeloid leukemia cell line HL60. A mechanism for RA-induced differentiation of HL60 cells may involve retinoylation (RA acylation) which is a post-translational modification of proteins occurring in many eukaryotic cell lines. Here, we found that differentiation by the synthetic retinoid (E)4-[3-(3,5-di-tert-butylphenyl)-3-oxo-1-propenyl]-benzoic acid (Ch55) was dose-dependent in serum-free medium.

Potential applications of cytodifferentiation therapy in hematologic malignancies.

Retinoids, including retinoic acid (RA), are naturally occurring and synthetic analogs of vitamin A that inhibit cell growth and induce cell differentiation in many experimental tumor models. Differentiation of the human myelogenous leukemia cell line HL-60 by RA led to the finding that cells from patients with acute promyelocytic leukemia (APL) are terminally differentiated by RA. One mechanism for the activity of RA in a variety of cell types involves the RA nuclear receptors (RA receptors [RARs] and retinoid X receptors), which have specific high-affinity binding sites for RA and some of its metabolites.

Unassembled (soluble) vimentin in human myeloid leukemia cell line HL60.

The intermediate filament proteins which include vimentin, desmin, and the keratins are one of three major classes of cytoskeletal proteins in eukaryotic cells. In this study we found that most of the vimentin of undifferentiated HL60 and cells induced to differentiate either along the monocytoid pathway by 12-O-tetradecanoylphorbol-13-acetate (TPA) or along the granulocytic pathway by retinoic acid was soluble in a buffer containing 1% Triton X-100/0.6 mol/l KCl in which the intermediate filament proteins usually are not soluble.

Tributyrin: a prodrug of butyric acid for potential clinical application in differentiation therapy.

Butyric acid (BA) induces cytodifferentiation in vitro of a wide variety of neoplastic cells. The potential clinical utility of BA is limited by the apparent difficulty of achieving effective concentrations because of its rapid metabolism and short plasma half-life. In this study we addressed two approaches that may achieve effective concentrations of BA in vivo.

Retinoylation of vimentin in the human myeloid leukemia cell line HL60.

Retinoylation (retinoic acid acylation) is a posttranslational modification of proteins occurring in many eukaryotic cell lines. The widespread occurrence of retinoylation suggests that it may play a role in many effects of retinoic acid (RA) on cells. The regulatory subunits of cyclic AMP-dependent protein kinase are retinoylated in the human myeloid leukemia cell line HL60 (Takahashi, N.

Covalent modification of proteins by ligands of steroid hormone receptors.

Retinoylation, acylation with retinoic acid (RA), is a covalent modification of proteins occurring in a variety of eukaryotic cell lines. In this study, we found that proteins in HL-60 cells were labeled by 17 beta-[3H]estradiol (E2), [3H]progesterone (Pg), 1 alpha,25-dihydroxy[3H]vitamin D3 [1,25(OH)2D3], [125I]triiodothyronine (T3), [125I]thyroxine (T4), and [3H]prostaglandin E2 (PGE2). All of these hormones, except PGE2, are ligands of the steroid hormone receptor family.

The covalent labeling of proteins by 17 beta-estradiol, retinoic acid, and progesterone in the human breast cancer cell lines MCF-7 and MCF-7/AdrR.

In this study we analyzed the covalent binding to proteins of 17 beta-estradiol (E2), retinoic acid (RA), and progesterone in MCF-7 and MCF-7/AdrR cells. MCF-7 cells have receptors for E2 and progesterone. MCF-7/AdrR cells do not have these receptors.

Retinoylation of the cAMP-binding regulatory subunits of type I and type II cAMP-dependent protein kinases in HL60 cells.

Retinoylation (retinoic acid acylation) is a post-translational modification of proteins occurring in a variety of eukaryotic cell lines. There are at least 20 retinoylated proteins in the human myeloid leukemia cell line HL60 (N. Takahashi and T.

Retinoylation of cytokeratins in normal human epidermal keratinocytes.

Retinoylation (retinoic acid acylation) is a covalent modification of proteins occurring in a variety of eukaryotic cell lines. In this study, we found that proteins in undifferentiated and squamous-differentiated normal human epidermal keratinocytes were retinoylated after treatment with [3H]retinoic acid. The major retinoylated proteins were identified as cytokeratins based on their profile in two-dimensional gel electrophoresis and their immunoreactivity with anti-keratin monoclonal antibodies.

Retinoylation of proteins in leukemia, embryonal carcinoma, and normal kidney cell lines: differences associated with differential responses to retinoic acid.

In HL60 cells a nuclear protein of Mr 55,000 is retinoylated, with the formation of a thioester bond. To gain further knowledge on the role of retinoylation we studied it in cell lines with varied responses to retinoic acid (RA). Compared to HL60 the extent of retinoylation (mol/cell) was about fivefold higher in HL60/MRI, a mutant which is more sensitive to RA than HL60.

Retinoic acid inhibits sodium butyrate-induced monocytic differentiation of HL60 cells while synergistically inducing granulocytoid differentiation.

The human myeloid leukemia cell line HL60 is an in vitro model to study myeloid differentiation. HL60 cells differentiate along different cell type lineages in response to a variety of compounds. The direction of differentiation is usually inducer-specific.

Novel heteroarotinoids: synthesis and biological activity.

In this study, 13 heteroarotinoids were synthesized. The key step in each preparation was the condensation of the appropriate chroman-, thiochroman-, or benzothienyl-substituted phosphorus ylide, obtained from the independent synthesis of the corresponding phosphonium salts, with selected polyene-substituted aldehyde esters. Nine of these heterocycles contained a thiochroman group, two had a chroman group, and two others had a benzothienyl system.

Retinoylation of HL-60 proteins. Comparison to labeling by palmitic and myristic acids.

Recent studies suggest that a retinoic acid (RA) nuclear receptor or a retinoylated nuclear protein may be involved in the action of RA. We showed previously (Takahashi, N., and Breitman, T.

Combinations of retinoic acid with either sodium butyrate, dimethyl sulfoxide, or hexamethylene bisacetamide synergistically induce differentiation of the human myeloid leukemia cell line HL60.

All-trans-retinoic acid (RA), sodium n-butyrate (NaB), hexamethylene bisacetamide (HMBA), and dimethyl sulfoxide (DMSO) induce differentiation of the human acute myeloid leukemia cell line HL60. In the clinic, RA, NaB, or HMBA induce complete or partial remissions. However, the achievement and maintenance of effective plasma concentrations and toxicity have been problems.