Annexin V inhibits the 12-O-tetradecanoylphorbol-13-acetate-induced activation of Ras/extracellular signal-regulated kinase (ERK) signaling pathway upstream of Shc in MCF-7 cells.
Annexin V is a Ca2+-dependent phospholipid binding protein. Although it has been shown to inhibit protein kinase C (PKC) in cell-free systems, its role in the intact cell is unclear. A stable MCF-7 human breast cancer cell overexpression system was established to investigate the function of annexin V. In these cells, 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced phosphorylation and kinase activity of ERK1/2 were suppressed. Morphological changes induced by TPA were reduced by annexin V overexpression as well as by the pan-PKC inhibitor, bisindolylmaleimide I, and by the mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK) inhibitor, PD98059. TPA-induced MEK1/2 and Raf-1 phosphorylation were reduced in these cells. The TPA-enhanced active Ras, and its association with Raf-1, were reduced. TPA treatment of MCF-7 cells caused an increased association of Shc with Grb2. However, this increased association was prevented in the annexin V-overexpressors. p21WAF/CIP1 is responsible for inhibition of cell cycle progression in MCF-7 cells. TPA induced the expression of p21WAF/CIP1 to a greater extent in MCF-7 parent and control plasmid cells than in annexin V overexpressors. PD98059 inhibited this increase, suggesting that TPA upregulation of p21WAF/CIP1 occurs via the MEK pathway, and that annexin V overexpression blunts it. This work shows that annexin V overexpression suppresses the TPA-induced Ras/ERK signaling by inhibiting at/or upstream of Shc, possibly through the inhibition of PKCs. Oncogene (2000).
Sato
H
H
Laboratory of Cellular Carcinogenesis and Tumor Promotion, National Cancer Institute, National Institute of Health, Bethesda, Maryland, MD 20892-4255, USA.
Ogata
H
H
De Luca
L M
LM
D017304:Annexin A5 / Q000494:pharmacology*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D015398:Signal Transduction / Q000187:drug effects*; D013755:Tetradecanoylphorbol Acetate / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D017304:Annexin A5; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate