methyl-2-5-dihydroxycinnamate and erbstatin

The authors examined the effect of a tyrosine kinase inhibitor, erbstatin, and its analogues on abl oncogene functions. Erbstatin and its stable analogue methyl 2,5-dihydroxycinnamate (2,5-MeC) inhibited the growth of v-ablts-NIH3T3 cells at the permissive temperature (33 degrees C) at lower concentrations than at the non-permissive temperature (39 degrees C). 2,5-MeC inhibited the morphological transformation and the activation of v-abl tyrosine kinase by the temperature shift (39 degrees C to 33 degrees C) more effectively than erbstatin. Previously the authors reported that erbstatin induced erythroid differentiation of K562 human chronic myelogenous leukaemia cells, so they examined the effect of erbstatin analogues on the erythroid differentiation. Among eight erbstatin analogues studied, ethyl 2,5-dihydroxycinnamate induced erythroid differentiation of K562 cells most effectively. Ethyl 2,5-dihydroxycinnamate also inhibited bcr-abl tyrosine kinase. These results indicate that the stable analogues of erbstatin suppress oncogene functions of Abl by inhibiting its tyrosine kinase.

Topics: Abelson murine leukemia virus; Animals; Cell Differentiation; Cell Line, Transformed; Cell Survival; Cell Transformation, Viral; Cinnamates; Genes, abl; Humans; Hydroquinones; Oncogene Proteins v-abl; Protein-Tyrosine Kinases

alpha 2-adrenoceptor-mediated contractions of the rabbit saphenous vein were previously found to be inhibited by wortmannin, a protein kinase inhibitor which blocks receptor-dependent phospholipase D activation. Since other studies have indicated that receptor-dependent phospholipase D activation required activity of a tyrosine kinase, we examined the influence of several tyrosine kinase inhibitors on both alpha 2-adrenoceptor-mediated contractions of rabbit saphenous vein and alpha 1-adrenoceptor-mediated contractions of rabbit aorta. Methyl 2,5-dihydroxycinnamate, genistein and erbstatin each caused non-competitive inhibition of rabbit saphenous vein contractions elicited by the alpha 2-adrenoceptor-selective agonist 5-bromo-6-[2-imidazolin-2-yl-amino]-quinoxaline (UK14304), yielding complete inhibition at 100 microM and IC50 values of 15, 35 and 40 microM respectively. By contrast, phenylephrine-induced dose-response curves in rabbit aorta were largely unaffected by tyrosine kinase inhibitors at 50 microM. In a separate analysis of intracellular Ca(2+)-dependent and extracellular Ca(2+)-dependent alpha 1-adrenoceptor responses of rabbit aorta, genistein (50 microM) did partially reduce the initial intracellular Ca(2+)-dependent response, but did not reduce maximal response. Methyl 2,5-dihydroxycinnamate (25 microM) had no effect on intracellular or extracellular Ca2+ responses in rabbit aorta. High K(+)-induced contractions of both rabbit saphenous vein and aorta were unaffected by up to 100 microM of the tyrosine kinase inhibitors. These results indicate an obligatory requirement for tyrosine kinase activity in alpha 2-adrenoceptor-mediated but not alpha 1-adrenoceptor-mediated vasoconstriction.

Topics: Animals; Aorta; Brimonidine Tartrate; Cinnamates; Dose-Response Relationship, Drug; Genistein; Hydroquinones; Isoflavones; Male; Muscle Contraction; Muscle, Smooth, Vascular; Phenylephrine; Protein-Tyrosine Kinases; Quinoxalines; Rabbits; Receptors, Adrenergic, alpha-1; Receptors, Adrenergic, alpha-2; Saphenous Vein; Vasoconstriction

Epidermal growth factor (EGF) induces transformed phenotypes in EGF receptor-overexpressing NIH3T3 (ER12) cells. Tyrosine kinase inhibitors such as erbstatin and its stable analogue methyl 2,5-dihydroxycinnamate inhibited the EGF-induced phenotypic changes in these cells; while 5'-O-methylerbstatin, an inactive analogue, did not. Methyl 2,5-dihydroxycinnamate inhibited intracellular tyrosine kinase activity in EGF-treated ER12 cells. Methyl 2,5-dihydroxycinnamate also delayed the EGF-induced DNA synthesis from the quiescent phase ER12 cells without showing irreversible cytotoxicity. It inhibited the DNA synthesis most efficiently at the early G1 phase. Thus, tyrosine kinase inhibitors may modify malignant phenotypes in EGF receptor-overexpressing neoplasms.

Topics: 3T3 Cells; Animals; Cell Differentiation; Cinnamates; Cytoskeleton; ErbB Receptors; Fibronectins; Hydroquinones; Immunoblotting; Kinetics; Mice; Protein-Tyrosine Kinases

Erbstatin and methyl 2,5-dihydroxycinnamate, related tyrosine kinase inhibitors, induced a morphological change in temperature-sensitive Rous sarcoma virus-transformed rat kidney (RSVts-NRK) that brought the cells close to the morphology of their normal counterpart. Erbstatin did not change the morphology of normal or Kirsten sarcoma virus-transformed rat kidney cells. Erbstatin also inhibited morphological transformation of RSVts-NRK cells induced by a shifting in temperature. Actin stress fibres were observed only in normal cells and not in transformed cells. Erbstatin induced stress fibre organization in transformed cells. Erbstatin and methyl 2,5-dihydroxycinnamate increased fibronectin gene expression in RSV-transformed cells. Thus, tyrosine kinase inhibitors induced normal phenotypes specifically in v-src-expressing cells.

Topics: Actins; Avian Sarcoma Viruses; Blotting, Northern; Cell Line, Transformed; Cell Transformation, Viral; Cinnamates; Fibronectins; Fluorescent Dyes; Gene Expression Regulation; Hydroquinones; Kidney; Nucleic Acid Hybridization; Protein-Tyrosine Kinases; RNA