-
Bioorganic & Medicinal Chemistry Letters May 2015Five new phorbol esters, (four phorbol diesters, 1-4, and one 4-deoxy-4α-phorbol diester, 5), as well as four known phorbol esters analogues (6-9) were isolated and...
Five new phorbol esters, (four phorbol diesters, 1-4, and one 4-deoxy-4α-phorbol diester, 5), as well as four known phorbol esters analogues (6-9) were isolated and identified from the branches and leaves of Croton tiglium. Their structures were elucidated mainly by extensive NMR spectroscopic, and mass spectrometric analysis. Among them, compound (1) was the first example of a naturally occurring phorbol ester with the 20-aldehyde group. Compounds 2-5, and 7-9 showed potent cytotoxicity against the K562, A549, DU145, H1975, MCF-7, U937, SGC-7901, HL60, Hela, and MOLT-4 cell lines, with IC50 values ranging from 1.0 to 43 μM, while none of the compounds exhibited cytotoxic effects on normal human cell lines 293T and LX-2, respectively. In addition, compound 3 exhibited moderate COX-1 and COX-2 inhibition, with IC50 values of 0.14 and 8.5 μM, respectively.
Topics: Anti-Inflammatory Agents, Non-Steroidal; Cell Line; Cell Proliferation; Croton; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase Inhibitors; Dose-Response Relationship, Drug; Humans; Molecular Structure; Phorbol Esters; Structure-Activity Relationship
PubMed: 25819096
DOI: 10.1016/j.bmcl.2015.03.017 -
Cytobios 1988Although the specific mechanisms by which phorbol ester tumour promoters exert their various effects are not known, their actions are mediated by cell membrane receptors...
Although the specific mechanisms by which phorbol ester tumour promoters exert their various effects are not known, their actions are mediated by cell membrane receptors which contain lipids as major components of the receptor complex. Since cell modulators such as retinoic acid (RA) and nitrosonornicotine (NNN) can alter cell lipids, the binding of a phorbol ester to cells was examined at time intervals when lipid changes mediated by these modulators occur. Epithelial cells prepared from hamster cheek pouches were treated with all-trans RA or NNN for varying periods of time, then specific binding of phorbol esters was investigated. Cells treated with RA for intervals up to 24 h showed decreased binding when compared with untreated cells. Those treated with NNN for up to 168 h showed increased specific binding. The results suggest that alterations in the cell lipids may affect the specific binding of phorbol esters to cells.
Topics: Animals; Cells, Cultured; Cheek; Cricetinae; Epithelium; Light; Lipid Metabolism; Nitrosamines; Phorbol Esters; Time Factors; Tretinoin
PubMed: 3208542
DOI: No ID Found -
The Journal of Biological Chemistry Jan 1987Phorbol ester sensitive EL4 cells become growth-inhibited and produce interleukin 2 when treated with phorbol-12, 13-dibutyrate. Resistant cells lack both responses. To...
Phorbol ester sensitive EL4 cells become growth-inhibited and produce interleukin 2 when treated with phorbol-12, 13-dibutyrate. Resistant cells lack both responses. To determine whether the defect in phorbol ester-resistant EL4 cells occurs pre- or post-transcriptionally, a hybridization assay for interleukin 2 mRNA was developed using two synthetic oligonucleotides complementary to mouse interleukin 2 mRNA as probes. Both probes hybridized to a 1-kilobase band in RNA from phorbol ester-treated sensitive cells. This RNA was detectable within 3 h of phorbol ester administration, and accumulation peaked by 12 h. The 1-kilobase band was induced in a concentration-dependent manner by 4-beta-phorbol-12, 13-dibutyrate but not by the inactive analog, 4-alpha-phorbol-12, 13-dibutyrate. No bands hybridizing with the interleukin 2 probe were detected in RNA isolated from unstimulated cells or from phorbol ester-resistant EL4 cells at any time up to 24 h following phorbol ester stimulation. The accumulation of the RNA in sensitive cells was blocked when the protein synthesis inhibitors, cycloheximide (75 microM) or puromycin (90 microM) were added within 1 h of the addition of phorbol ester. If cycloheximide was added 2 or more h after phorbol ester treatment, superinduction of the 1-kilobase band was observed. These results indicate that the failure of phorbol ester-resistant EL4 cells to produce interleukin 2 is due to a defect proximal to interleukin 2 transcription and that the accumulation of interleukin 2 mRNA in phorbol ester-sensitive EL4 cells requires protein synthesis.
Topics: Animals; Cell Line; Cycloheximide; Drug Resistance; Interleukin-2; Mice; Nucleic Acid Hybridization; Oligonucleotides; Phorbol 12,13-Dibutyrate; Phorbol Esters; Puromycin; RNA, Messenger; Thymoma; Thymus Neoplasms; Transcription, Genetic
PubMed: 3491822
DOI: No ID Found -
European Neuropsychopharmacology : the... Mar 1996Chronic lithium treatment in rats has been reported to decrease protein kinase C alpha isozyme in hippocampal membranes. We gave phorbol ester, a protein kinase C...
Chronic lithium treatment in rats has been reported to decrease protein kinase C alpha isozyme in hippocampal membranes. We gave phorbol ester, a protein kinase C activator, i.c.v. to rats treated with acute or chronic lithium. Low dose phorbol ester causes a marked hypoactivity and high dose phorbol ester causes a barrel rolling behavior, but no behavioral interactions with lithium treatment were observed.
Topics: Animals; Behavior, Animal; Injections, Spinal; Lithium; Male; Motor Activity; Phorbol Esters; Rats; Rats, Sprague-Dawley; Time Factors
PubMed: 8866936
DOI: 10.1016/0924-977x(95)00054-s -
Molecular Cancer Therapeutics Jan 2005The diacylglycerol signaling pathway, involving protein kinase C (PKC) and RasGRP, is a promising therapeutic target for both cancer and other indications. The phorbol...
The diacylglycerol signaling pathway, involving protein kinase C (PKC) and RasGRP, is a promising therapeutic target for both cancer and other indications. The phorbol esters, ultrapotent diacylglycerol analogues, bind to and activate PKC and RasGRP. Here, using fluorescent phorbol esters and complementary fluorescent PKC and RasGRP constructs, we determined the localization of the phorbol ester as a function of time after addition and how the resultant PKC or RasGRP3 translocation related to ligand localization. For these studies, we prepared fluorescently labeled phorbol esters of varying lipophilicities based on the BODIPY FL (green) or BODIPY 581/591 (red) fluorophores, and by using fusion constructs of green fluorescent protein or DsRed with PKC isoforms or RasGRP3 expressed in Chinese hamster ovary cells, we simultaneously compared the kinetics and pattern of localization of PKC or RasGRP3 with that of the fluorescent red or green phorbol esters. Binding assays showed that the fluorescent derivatives were potent ligands. Uptake followed a one-compartment pharmacokinetic model with a half-time of minutes to hours, depending on the ligand, and all of the fluorescent phorbol esters localized primarily to intracellular membranes, with little plasma membrane localization. The fluorescent phorbol esters induced translocation of and generally colocalized with PKCdelta or RasGRP3. However, PKCalpha and, initially, PKCdelta, translocated to the plasma membrane, in which little phorbol ester accumulated. The findings argue that the rate of uptake of phorbol esters influences the subsequent pattern of PKCdelta translocation, and that the specificity for PKCalpha translocation is dominated by factors other than the localization of the ligand.
Topics: Animals; Biological Transport; CHO Cells; Cricetinae; Fluorescent Dyes; Guanine Nucleotide Exchange Factors; Humans; Kinetics; Ligands; Microscopy, Confocal; Phorbol 12,13-Dibutyrate; Protein Kinase C; Protein Transport; Recombinant Fusion Proteins; Tetradecanoylphorbol Acetate; ras Guanine Nucleotide Exchange Factors
PubMed: 15657361
DOI: No ID Found -
Molecular Pharmacology Sep 1987We have investigated the effect of phorbol dibutyrate on intracellular routing of the asialoglycoprotein receptor (ASGP-R) in a human hepatoma cell line, Hep G2. We have...
We have investigated the effect of phorbol dibutyrate on intracellular routing of the asialoglycoprotein receptor (ASGP-R) in a human hepatoma cell line, Hep G2. We have previously shown that this agent causes a net redistribution of 50% of cell surface receptors to the cell interior (Fallon, R.J., and A.L. Schwartz, J. Biol. Chem. 261: 15081-15089 (1986)). To explore the mechanism of this effect, we measured the rate constants of receptor and ligand movement during internalization, ligand-receptor uncoupling, sorting of ligand to degradative sites or return to the extracellular medium, and return of receptor to the plasma membrane. The rate of internalization of bound asialoorosomucoid (ASOR) is identical in phorbol ester-treated and control cells, over a range of ASOR concentrations from 5 to 125 nM. The pathway of ligand recycling returns approximately 30% of internalized ASOR undegraded to the extracellular medium; phorbol esters do not modify the extent of this pathway in Hep G2 cells nor the kinetics of recovery of undegraded ASOR in the medium (t1/2 = 20 min). The rate of ligand-receptor uncoupling is similarly unaltered by phorbol esters, as measured by the amount of free ASOR that accumulates intracellularly and exits the cell after saponin permeabilization. In contrast, phorbol esters cause a rapid (less than 5 min) 50% decrease in receptor return to the cell surface from internal sites. This suggests that 1) phorbol esters interfere with selected specific sites in receptor and ligand pathways of receptor-mediated endocytosis and 2) the apparent net "internalization" of ASGP-R by phorbol esters results from an inhibition of receptor recycling to the cell surface and not from a direct stimulation of the internalization process.
Topics: Asialoglycoprotein Receptor; Asialoglycoproteins; Cell Line; Cell Membrane; Endocytosis; Humans; Kinetics; Ligands; Orosomucoid; Phorbol 12,13-Dibutyrate; Phorbol Esters; Primaquine; Receptors, Immunologic
PubMed: 3478583
DOI: No ID Found -
Journal of Biomolecular Structure &... 2015C1 domains are small zinc-binding structural units of approximately 50 amino acids, originally discovered as lipid-binding modules in protein kinase C (PKC) isoforms. C1...
C1 domains are small zinc-binding structural units of approximately 50 amino acids, originally discovered as lipid-binding modules in protein kinase C (PKC) isoforms. C1 domains that bind and respond to the DAG/phorbol ester are termed as typical, and those that do not respond to DAG/phorbol ester are termed as atypical. To design molecules targeting a specific C1 domain for regulating a specific disease state, it is important to understand the factors that make a C1 domain responsive to DAG/phorbol ester. Here, we determined the volume and surface area of the ligand-binding site for all known C1 domains. No correlation was found between the volume/surface area of ligand-binding site and the DAG/phorbol ester-binding affinity. Solvated molecular dynamics simulation reveals that the presence of water molecules affects the flexibility of the ligand-binding site. Contributions of the binding site residues, their orientations, and the membrane lipids on the responsiveness of a C1 domain towards DAG/phorbol ester have been discussed.
Topics: Amino Acid Sequence; Animals; Binding Sites; Diglycerides; Humans; Isoenzymes; Molecular Docking Simulation; Molecular Dynamics Simulation; Molecular Sequence Data; Mutation; Phorbol Esters; Pliability; Protein Binding; Protein Kinase C; Protein Structure, Secondary; Protein Structure, Tertiary; Thermodynamics; Water
PubMed: 24666138
DOI: 10.1080/07391102.2014.895679 -
FEBS Letters Feb 1988The ability of the tumor-promoting phorbol ester 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA) to induce protein kinase C (PKC) translocation and lysosomal...
The ability of the tumor-promoting phorbol ester 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA) to induce protein kinase C (PKC) translocation and lysosomal enzyme release was examined in skin fibroblasts from normal subjects and from patients with cystic fibrosis (CF). As compared to normal fibroblasts, those CF exhibited: (i) an increased sensitivity to the effect of PMA on the disappearance of PKC from cytosolic fractions as well as a greater and earlier recovery, in the membrane fraction, of the PKC activity lost in the cytosolic fraction; (ii) an earlier response to PMA for its effect on beta-N-acetylglucosaminidase release. In contrast, the inactive phorbol ester 4 alpha-phorbol 12,13-didecanoate (4 alpha PDD) proved ineffective in inducing PKC translocation and beta-N-acetylglucosaminidase release in both normal and CF fibroblasts. The data suggest a defect in the regulation of PKC activity in CF fibroblasts, which may lead to altered secretion.
Topics: Acetylglucosaminidase; Cystic Fibrosis; Dose-Response Relationship, Drug; Fibroblasts; Humans; Lysosomes; Phorbol Esters; Protein Kinase C; Tetradecanoylphorbol Acetate; Time Factors
PubMed: 3345834
DOI: 10.1016/0014-5793(88)80818-4 -
The Biochemical Journal Apr 1991We examined the effects of the phorbol ester phorbol 12-myristate 13-acetate (PMA) on the rate of hexose transport into 3T3-L1 adipocytes. Exposure of adipocytes to PMA... (Comparative Study)
Comparative Study
We examined the effects of the phorbol ester phorbol 12-myristate 13-acetate (PMA) on the rate of hexose transport into 3T3-L1 adipocytes. Exposure of adipocytes to PMA (1 microM) for 60 min results in a 1.7-2.5-fold increase in the rate of hexose transport. This effect was mediated by translocation of two isoforms of glucose transporters to the plasma membrane, as determined by labelling in situ, photoaffinity labelling with a membrane-impermeant glucose analogue, and by immunoblotting of subcellular fractions. The PMA-induced stimulation of both transport and transporter translocation was substantially less than that induced by insulin in this cell line; the PMA-induced increase in plasma-membrane GLUT 1 and GLUT 4 transporter isoforms was only about 40% and 10% respectively of that induced by insulin. We suggest that the stimulation of transport by insulin and PMA occurs via different mechanisms, which is manifested by the ability of insulin to induce a much greater increase in the plasma-membrane content of GLUT 4 compared with the phorbol ester.
Topics: Adipose Tissue; Biological Transport; Deoxyglucose; Glucose; Humans; Insulin; Kinetics; Monosaccharide Transport Proteins; Phorbol Esters; Phosphorylation; Protein Kinase C; Tetradecanoylphorbol Acetate
PubMed: 2018470
DOI: 10.1042/bj2750145 -
NatureAlthough the biochemical mechanism of action of phorbol ester tumour promoters is not fully understood, it is known that phorbol ester binding to the cell surface causes...
Although the biochemical mechanism of action of phorbol ester tumour promoters is not fully understood, it is known that phorbol ester binding to the cell surface causes rapid changes in calcium flux and phospholipid metabolism. A protein kinase activity has recently been described which is dependent on calcium and acidic phospholipids and is further enhanced by diacylglycerol. Previously, we have observed that phorbol ester treatment of EL4 mouse thymoma cells causes a rapid decrease in cytosolic calcium, phospholipid-dependent protein kinase (Ca, PL-PK) activity, which is mediated through the specific phorbol ester cell-surface receptors identified on EL4 cells. We now show that treatment of parietal yolk sacs (PYS-2) cells with biologically active 12-O-tetradecanoyl phorbol-13-acetate (TPA) provokes a rapid decrease in cytosolic Ca, PL-PK activity that is accompanied by a significant increase in the amount of Ca, PL-PK activity associated with the plasma membrane fraction. These results suggest that the rapid and tight association of Ca, PL-PK activity with the plasma membrane may be an early event in mediating some of the effects of phorbol esters.
Topics: Animals; Calcium; Cell Membrane; Female; Phorbol Esters; Phorbols; Phospholipids; Protein Kinases; Tetradecanoylphorbol Acetate; Time Factors; Yolk Sac
PubMed: 6828143
DOI: 10.1038/301621a0