Thrombin induces EGF receptor expression and cell proliferation via a PKC(delta)/c-Src-dependent pathway in vascular smooth muscle cells.
OBJECTIVE
Thrombin upregulates expression of several proteins in vascular smooth muscle cells (VSMCs) which may contribute to atherosclerosis. Here, we investigated the mechanisms underlying thrombin-induced EGF receptor (EGFR) expression and its effect on VSMCs.


RESULTS
Normal rat VSMCs were used. First, Western blotting and RT-PCR analyses showed that thrombin induces the expression of EGFR at transcription and translation levels in VSMCs. Second, pharmacological inhibitors, dominant negative mutants, and short hairpin RNA interference (shRNA) technology enabled us to demonstrate that thrombin-induced EGFR expression is mediated through PKC(delta)/c-Src-dependent transactivation of EGFR linking to PI3K/Akt and ERK1/2. We further investigated whether the transcription factors AP-1 and NF-kappaB are involved in this response by a promoter assay. Finally, data obtained by using EGFR shRNA technology and XTT assay demonstrated that thrombin-enhanced VSMC proliferation was mediated through upregulation of EGFR.


CONCLUSIONS
Our results demonstrate that thrombin-enhanced VSMC proliferation was mediated through upregulation of EGFR via a PKC(delta)/c-Src-dependent transactivation of EGFR, PI3K-Akt, and ERK, and AP-1/NF-kappaB pathway.
Hsieh
Hsi-Lung
HL
Department of Nursing, Division of Basic Medical Sciences, Chang Gung Institute of Technology, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan.
Tung
Wei-Hsuan
WH
Wu
Cheng-Ying
CY
Wang
Hui-Hsin
HH
Lin
Chih-Chung
CC
Wang
Tze-Shyuan
TS
Yang
Chuen-Mao
CM
D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D066246:ErbB Receptors / Q000235:genetics*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000502:physiology; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D016328:NF-kappa B / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D010766:Phosphorylation; D051745:Protein Kinase C-delta / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013917:Thrombin / Q000494:pharmacology*; D018808:Transcription Factor AP-1 / Q000502:physiology; D019061:src-Family Kinases
D000081247:CSK Tyrosine-Protein Kinase; D004247:DNA; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D051745:Protein Kinase C-delta; D011505:Protein-Tyrosine Kinases; D051057:Proto-Oncogene Proteins c-akt; D013917:Thrombin; D018808:Transcription Factor AP-1; D019061:src-Family Kinases; C497260:Prkcd protein, rat