Potent and Specific Inhibition of p60vsrc Protein Kinase Both in Vivo and in Vitro by Radicicol

Ho Jeong Kwon, Minoru Yoshida, Yasuhisa Fukui, Sueharu Horinouchi, Teruhiko Beppu

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127 Citations (Scopus)


A fungal metabolite, radicicol, with a macrocyclic ring induced the reversal of transformed phenotypes of v-wc-transformed fibroblasts (Rous sarcoma virus-transformed 3Y1 rat fibroblast) at a quite low concentration of 0.1 ng/ml. Actin stress fibers reappeared in the transformed cells after treatment with radicicol. Radicicol reduced the intracellular level of autophosphorylation of p60v sre as well as the level of other tyrosine-phosphorylated proteins in a dose-dependent manner. In vitro kinase assay revealed that radicicol effectively inhibited not only autophosphorylation but also transphosphorylation activities of purified p5Qvsrc wjtn a concentration producing 50% inhibition of 0.1 ng/ml. However, radicicol showed no inhibitory effect on protein kinase C or protein kinase A. These results suggest that radicicol is a novel and specific protein-tyrosine kinase inhibitor and that the decreased level of tyrosine kinase activity of p60v~src causes reversion of transformed phenotypes of Rous sarcoma virus-transformed 3Y1 rat fibroblast. Furthermore, differentiation of Friend leukemia cells, which is one of the known characteristic phenomena associated with the inhibition of tyrosine kinase, was also induced in the concentration range of 0.05-0.5 Mg/ml, suggesting that the agent is useful for the analysis of differentiation as well as the kinase-mediated signal transduction.

Original languageEnglish
Pages (from-to)6926-6930
Number of pages5
JournalCancer Research
Issue number24
Publication statusPublished - 1992 Dec

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research


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