Synergistic stimulation of early events and DNA synthesis by phorbol esters, polypeptide growth factors, and retinoids in cultured fibroblasts

Dicker, Phillip

doi:10.1002/jss.400110109

Cited by 60 publications

(20 citation statements)

References 32 publications

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“…4B (24,(27)(28)(29)(30). Similar results were obtained when DNA synthesis was measured as percentage of labeled nuclei after autoradiography (Fig.…”

Section: Resultssupporting

confidence: 80%

“…In the presence of both OAG and retinoic acid, the dose of PDGF or FDGF required to produce halfmaximal stimulation was markedly reduced (results not shown). Identical synergistic effects have been reported with phorbol esters (25,27,28,45) and with teleocidin (31). If phorbol esters and OAG stimulate DNA synthesis by a common mechanism, these agents should not interact synergistically in stimulating DNA synthesis.…”

Section: Resultsmentioning

confidence: 64%

“…A crucial step for establishing that some or all these events are mediated through activation of protein kinase C and that this phosphotransferase system may play a central role in the regulation of cellular growth is to show that exogenously added diacylglycerols can mimic the action of the phorbol esters in stimulating reinitiation of DNA synthesis and cell division in quiescent cells. To test whether diacylglycerol and phorbol esters act as functional analogs, we chose untransformed Swiss 3T3 cells as a model system because of the considerable body of information available on their mitogenic response to phorbol esters in well-defined media (21,25,(27)(28)(29)(30)(31)(32)(33) and because these cells possess high-affinity specific receptors for [3H]PBt2 that mediate the effects of phorbol esters on mitogenesis (21,(31)(32)(33).…”

mentioning

confidence: 99%

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Diacylglycerol stimulates DNA synthesis and cell division in mouse 3T3 cells: role of Ca2+-sensitive phospholipid-dependent protein kinase.

Rozengurt¹,

Rodrı́guez-Peña²,

Coombs³

et al. 1984

Proc. Natl. Acad. Sci. U.S.A.

227

102

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The synthetic diacylglycerol l-oleoyl-2-acetylglycerol competes directly with [ H]phorbol 12,13-dibutyrate for common binding sites in monolayer cultures of Swiss 3T3 cells and rapidly stimulates the phosphorylation of a Mr 80,000 cellular protein that has recently been shown to reflect the activation of protein kinase C in intact cells. Thus, this diacylglycerol provided a useful tool to determine whether exogenously added diacyIglycerols can mimic the potent tumor promoter phorbol ester in eliciting DNA synthesis and cell division in quiescent cells. We found that OAG acts synergistically with insulin and other growth factors to stimulate reinitiation of cell proliferation, and several lines of evidence indicate that OAG shares with phorbol esters a common pathway of mitogenic action via stimulation of protein kinase C activity in intact 3T3 cells. The findings support the hypothesis that diacylglycerols represent endogenous analogs of phorbol esters and raise the possibility that diacylglycerols generated in the plasma membrane could act as a mitogenic signal for quiescent cells.Ca2+-sensitive phospholipid-dependent protein kinase (protein kinase C) is a widely distributed cyclic nucleotide-and calmodulin-independent phosphotransferase (1-3) that is activated by unsaturated diacylglycerols in the presence of phospholipids and physiological concentrations of Ca2+ (4)(5)(6). Recent studies with cell-free preparations (7-10) as well as with intact fibroblasts (11) have shown that the potent tumor promoters of the phorbol ester family (12) (13,14) and that 1,2-diacylglycerols compete with this radioactive ligand for common binding sites (15). It has been hypothesized that the high-affinity specific receptor for phorbol esters that was detected in a wide variety of cells and tissues (16-21) is a complex formed between protein kinase C, Ca2 , and membrane phospholipids (13,22) and that unsaturated diacylglycerols generated by phospholipid breakdown (22, 23) may represent the long-sought endogenous analogs of the phorbol esters and structurally related plant diterpenes (15,(23)(24)(25). A critical test of this hypothesis required experiments with intact cells.Phorbol esters are not only potent tumor promoters (12, 26) but also they induce a complex array of early biological responses in cultured cells (24,26), as well as stimulate DNA synthesis and cell division in quiescent cells (21,25,27). A crucial step for establishing that some or all these events are mediated through activation of protein kinase C and that this phosphotransferase system may play a central role in the regulation of cellular growth is to show that exogenously added diacylglycerols can mimic the action of the phorbol esters in stimulating reinitiation of DNA synthesis and cell division in quiescent cells. To test whether diacylglycerol and phorbol esters act as functional analogs, we chose untransformed Swiss 3T3 cells as a model system because of the considerable body of information available on their mitogenic response to phorbol ester...

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“…4B (24,(27)(28)(29)(30). Similar results were obtained when DNA synthesis was measured as percentage of labeled nuclei after autoradiography (Fig.…”

Section: Resultssupporting

confidence: 80%

Section: Resultsmentioning

confidence: 64%

mentioning

confidence: 99%

See 1 more Smart Citation

Diacylglycerol stimulates DNA synthesis and cell division in mouse 3T3 cells: role of Ca2+-sensitive phospholipid-dependent protein kinase.

Rozengurt¹,

Rodrı́guez-Peña²,

Coombs³

et al. 1984

Proc. Natl. Acad. Sci. U.S.A.

227

102

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“…Phorbol diesters, such as PMA, are tumor promoters and are capable of potentiating the mitogenic response of growth factors such as EGF (73,74). The mechanism of tumor promotion by these agents remains a mystery but has generally been ascribed to activation of the serine/threonine kinase PKC.…”

Section: The Role Of Pkc and Map Kinase In Pma-induced Phosphorylatiomentioning

confidence: 99%

Cross-talk between Phorbol Ester-mediated Signaling and Tyrosine Kinase Proto-oncogenes

Emkey

Kahn

1997

Journal of Biological Chemistry

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The tumor-promoting phorbol ester, phorbol 12-myristate 13-acetate (PMA), acutely stimulates the tyrosine phosphorylation of proteins of approximately 190, 120, and 70 kDa in the well differentiated Fao rat hepatoma cell line. This phosphorylation is dependent on protein kinase C (PKC) and is abolished by down-regulation of PKC or pretreatment with a PKC inhibitor. Purification of the 190-kDa tyrosine-phosphorylated protein revealed that it consists of both ErbB2 and ErbB3. Following PMA-induced tyrosine phosphorylation, ErbB2 and ErbB3 were able to associate with the SH2 domains of several signaling proteins including the p85␣ subunit of phosphatidylinositol 3-kinase, Syp, and Grb2. The 120-kDa protein phosphorylated in response to PMA consists of at least two proteins: focal adhesion kinase that exhibits a minor increase in tyrosine phosphorylation following treatment with PMA, and a major 120-kDa tyrosine-phosphorylated species in PMA-stimulated Fao cells which as yet is unidentified. Similarly, the 70-kDa tyrosine-phosphorylated protein also appears to represent more than one protein, including paxillin and a second protein of similar mobility which appears to be the major tyrosine phosphorylation in response to PMA. Both ErbB2 and paxillin also exhibit reduced migration on SDS-polyacrylamide gel electrophoresis following PMA treatment, suggesting that they are also phosphorylated on serine/threonine residues. The mobility shift of both of these proteins is abolished by treatment with inhibitors of PKC or mitogen-activated protein kinase/ extracellular signal-related kinase kinase. These results suggest a novel mechanism of cross-talk between the serine/threonine kinase PKC and tyrosine phosphorylation pathways. The activation of ErbB2 and ErbB3 that is initiated by PMA may contribute to the tumor promoting activity of these compounds.The ErbB (HER) family of receptor tyrosine kinases consists of the following four members: ErbB1 (the epidermal growth factor receptor; EGFR), 1 ErbB2/Neu, ErbB3, and ErbB4 (1-5).The hallmarks of this family of proteins include the presence of two cysteine-rich regions in the extracellular domain, a single transmembrane domain, and, with the exception of ErbB3 (6), an intrinsic tyrosine kinase activity contained in the large intracellular domain (7). In addition to the role of ErbB1 in EGF action, members of the ErbB family are often overexpressed in various human tumors (8, 9). Many human breast and ovarian carcinomas contain elevated levels of ErbB2 that result in constitutive activation of its intrinsic tyrosine kinase activity (8, 10 -12). This correlates with a poor clinical prognosis (1,7,9,13,14). Similarly, elevated levels of expression and tyrosine phosphorylation of ErbB3 have been detected in several breast cancer cell lines (3,15). It is clear that constitutive activation of the intrinsic kinase activity of these receptors is a crucial step in the oncogenic process (16). Activation of the ErbB family of receptors depends on formation of homodimers or heterodimers wi...

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“…Tumor promoters can modulate the action of epidermal growth factor (EGF) by reducing EGF receptor binding (1-4) and internalization (5, 6) and by potentiating the mitogenic activity of EGF in quiescent cells (7,8). Upon binding to cells, EGF stimulates the tyrosine phosphorylation of its receptors (9, 10) via a receptor-associated kinase activity.…”

Section: Introductionmentioning

confidence: 99%

Tumor promoters block tyrosine-specific phosphorylation of the epidermal growth factor receptor.

Friedman¹,

Frackelton²,

Ross³

et al. 1984

Proc. Natl. Acad. Sci. U.S.A.

199

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Tyrosine-specific phosphorylation of the epidermal growth factor (EGF) receptor in hormonally stimulated A431 cells is blocked by three chemically distinct classes of tumor promoters. Tumor-promoting esters of the diterpene phorbol (phorbol 12-myristate 13-acetate, P-phorbol 12,13-dibutyrate, and (3-phorbol 12,13-didecanoate), indole alkaloids (teleocidin and lyngbyatoxin A), and polyacetates (aplysiatoxin and debromoaplysiatoxin) all inhibited EGF-stimulated phosphorylation of the receptor. Non-tumor-promoting analogs (,Bphorbol, a-phorbol 12,13-didecanoate, and hydrolyzed teleocidin) had no effect on the levels of receptor phosphorylation.The ED5o values of the inhibitory effect (0.1-3 ng/ml) reflected the relative tumor-promoting abilities of these compounds in vivo. None of the tumor promoters tested significantly de-creased the overall specific binding of 125I-labeled EGF to A431 cells. Scatchard analysis, however, revealed two apparent EGF receptors in this cell type. The dose-responses for tumor-promoter inhibition of EGF receptor tyrosine phosphorylation and high-affinity EGF binding were similar, suggesting that the same initial event is responsible for both effects.This demonstrates a correlation between modulation of EGF receptor binding and phosphorylation of tyrosine by tumor promoters. The data suggest a possible role for protein kinase C, the putative cellular receptor for these tumor promoters, in the mechanism of action.Tumor promoters can modulate the action of epidermal growth factor (EGF) by reducing EGF receptor binding (1-4) and internalization (5, 6) and by potentiating the mitogenic activity of EGF in quiescent cells (7,8). Upon binding to cells, EGF stimulates the tyrosine phosphorylation of its receptors (9, 10) via a receptor-associated kinase activity. The potential regulatory role of tyrosine kinase activity is suggested by its association with the action of other growth factors (insulin and platelet-derived growth factor) (11-13) and its apparent requirement for oncogenic transformation by a number of retroviruses (14,15). This led us to examine whether the effects of tumor promoters on the action of EGF involved changes in receptor phosphorylation.We have found that three chemically distinct classes of tumor promoters [esters of the diterpene phorbol, indole alkaloids (16), and polyacetates (17) 32Pi Labeling and Detergent Extraction of Cells. Low-density cultures (105 cells per 35-mm well) of A431 cells were preincubated with 32p; at 0.5 mCi/ml in phosphate-free DME medium plus dialyzed heat-inactivated fetal calf serum for 3-4 hr at 37°C. Dimethyl sulfoxide (Me2SO; final concentration 1%), tumor promoters, or nonpromoting analogs (dissolved in Me2SO) were added for 10 min. EGF was then added for an additional 40 min. The cultures were placed on ice, the binding media were removed, and the cells were scraped and extracted with Tris-buffered Triton (10 mM Tris'HCl/1% Triton X-100/10 mM NaCl/5 mM EDTA/1 mM phenylmethylsulfonyl fluoride/0.1% bovine serum albumin, pH 8).Phosph...

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Synergistic stimulation of early events and DNA synthesis by phorbol esters, polypeptide growth factors, and retinoids in cultured fibroblasts

Cited by 60 publications

References 32 publications

Diacylglycerol stimulates DNA synthesis and cell division in mouse 3T3 cells: role of Ca2+-sensitive phospholipid-dependent protein kinase.

Diacylglycerol stimulates DNA synthesis and cell division in mouse 3T3 cells: role of Ca2+-sensitive phospholipid-dependent protein kinase.

Cross-talk between Phorbol Ester-mediated Signaling and Tyrosine Kinase Proto-oncogenes

Tumor promoters block tyrosine-specific phosphorylation of the epidermal growth factor receptor.

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