Studies on the mechanism of rapid activation of protein tyrosine phosphorylation activities, particularly c-Src kinase, by TCDD in MCF10A

Olga Mazina, Sujin Park, Hiromi Sano, Patrick Wong, Fumio Matsumura

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

While the process of the Ah receptor activation leading to cytochrome P450 induction has been well studied, the mechanism and the process through which the Ah receptor activates tyrosine kinases, within a few minutes of its ligand binding, is not known. Previously, it was reported by Tannheimer et al. (Carcinogenesis 1998; 19:1291-1297) that TCDD causes rapid induction of tyrosine phosphorylation activities in the MCF10A human mammary epithelial cell line. To study the mechanistic aspect of this phenomenon, particularly that occurs within a few minutes after administration, we first studied the effect of insulin on MCF10A under serum free conditions with added EGF. The addition of insulin induced a rapid (5 min) tyrosine phosphorylation on several 160-190 kDa proteins which was followed by significant dephosphorylation activities on these proteins by 15 min. TCDD increased the rate of tyrosine phosphorylation on those proteins but at 15 min, the level of phosphorylation was still high. When insulin and TCDD were added together, the ability of insulin to induce de-phosphorylation by 15 min disappeared. Such an action of TCDD was accompanied by an increase in the titer of the activated form of Src kinase (i.e. c-Src protein with 418 tyrosine phosphorylation), and a concomitant decrease in the level of 529 tyrosine phosphorylated form (an inactivated form). The TCDD-induced activation of c-Src could be blocked by pretreated MCF10A cells with antisense oligonucleotides against c-src or with a specific inhibitor of Src kinase, PP-2. These results support the conclusion that c-Src kinase is at least one of the earliest and the most upstream components of toxic signaling of the Ah-receptor activated by TCDD through the posttranscriptional process.

Original languageEnglish (US)
Pages (from-to)313-321
Number of pages9
JournalJournal of Biochemical and Molecular Toxicology
Volume18
Issue number6
DOIs
StatePublished - Jan 1 2005
Externally publishedYes

Keywords

  • c-Src Kinase
  • MCF10A
  • Rapid Activation
  • TCDD
  • Tyrosine Phosphorylation

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Toxicology
  • Health, Toxicology and Mutagenesis

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