PKC-δ/c-Src-mediated EGF receptor transactivation regulates thrombin-induced COX-2 expression and PGE2 production in rat vascular smooth muscle cells

Hsi Lung Hsieh, Chi Chin Sun, Tze Shyuan Wang, Chuen Mao Yang*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

57 Scopus citations


The thrombin/proteinase-activated receptors (PARs) have been shown to regulate smooth muscle cell proliferation, migration, and vascular maturation. Thrombin up-regulates expression of several proteins including cyclooxygenase (COX)-2 in vascular smooth muscle cells (VSMCs) and contributes to vascular diseases. However, the mechanisms underlying thrombin-regulated COX-2 expression in VSMCs remain unclear. Western blotting, RT-PCR, and EIA kit analyses showed that thrombin induced the expression of COX-2 mRNA and protein and PGE2 release in a time-dependent manner, which was attenuated by inhibitors of PKC (GF109203X and rottlerin), c-Src (PP1), EGF receptor (EGFR; AG1478) and MEK1/2 (U0126), or transfection with dominant negative mutants of PKC-δ, c-Src or extracellular regulated kinase (ERK) and ERK1 short hairpin RNA interference (shRNA). These results suggest that transactivation of EGFR participates in COX-2 expression induced by thrombin in VSMCs. Accordingly, thrombin stimulated phosphorylation of ERK1/2 which was attenuated by GF109203X, rottlerin, PP1, GM6001, CRM197, AG1478, or U0126, respectively. Furthermore, this up-regulation of COX-2 mRNA and protein was blocked by selective inhibitors of AP-1 and NF-κB, curcumin and helenalin, respectively. Moreover, thrombin-stimulated activation of NF-κB, AP-1, and COX-2 promoter activity was blocked by the inhibitors of c-Src, PKC, EGFR, MEK1/2, AP-1 and NF-κB, suggesting that thrombin induces COX-2 promoter activity mediated through PKC(δ)/c-Src-dependent EGFR transactivation, MEK-ERK1/2, AP-1, and NF-κB. These results demonstrate that in VSMCs, activation of ERK1/2, AP-1 and NF-κB pathways was essential for thrombin-induced COX-2 gene expression. Understanding the regulation of COX-2 expression and PGE2 release by thrombin/PARs system on VSMCs may provide potential therapeutic targets of vascular inflammatory disorders including arteriosclerosis.

Original languageEnglish
Pages (from-to)1563-1575
Number of pages13
JournalBiochimica et Biophysica Acta - Molecular Cell Research
Issue number9
StatePublished - 09 2008
Externally publishedYes


  • COX-2
  • EGF receptor
  • ERK1/2
  • Thrombin
  • Vascular smooth muscle cell


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