Oxidative stress in MCF-7 cells is involved in the effects of retinoic acid-induced activation of protein kinase C-δ on insulin-like growth factor-I secretion and synthesis

2010 ◽  
Vol 20 (2) ◽  
pp. 101-109 ◽  
Author(s):  
Young-Il Oh ◽  
Jong-Hoon Kim ◽  
Chang-Won Kang
1998 ◽  
Vol 18 (10) ◽  
pp. 5888-5898 ◽  
Author(s):  
Weiqun Li ◽  
Yi-Xing Jiang ◽  
Jiachang Zhang ◽  
Lilian Soon ◽  
Lawrence Flechner ◽  
...  

ABSTRACT To investigate the potential role of protein kinase C-δ (PKC-δ) in insulin-like growth factor I receptor (IGF-IR)-mediated cell transformation, an oncogenic gag-IGF-IR β-fusion receptor lacking the entire extracellular domain, which was designated NM1, and a full-length IGF-IR were coexpressed with either wild-type PKC-δ (PKC-δWT) or an ATP-binding mutant of PKC-δ (PKC-δK376R) in NIH 3T3 fibroblasts. While overexpression of PKC-δWT did not affect NM1- and IGF-IR-induced focus and colony formation of NIH 3T3 cells, expression of PKC-δK376R severely impaired these events. In contrast, NM1-mediated cell growth in monolayer was not affected by coexpressing PKC-δK376R. PKC-δWT and PKC-δK376R were constitutively phosphorylated on a tyrosine residue(s) in the NM1- and IGF-IR-expressing cells and were associated with them in an IGF-I-independent manner. Activated IGF-IR was able to phosphorylate purified PKC-δ in vitro and stimulated its kinase activity. Furthermore, the level of endogenous PKC-δ protein was up-regulated through transcriptional activation in response to long-term IGF-IR activation. Taken together, our results demonstrate that PKC-δ plays an important role in IGF-IR-mediated cell transformation, probably via association of the receptor with PKC-δ and its activation through protein up-regulation and tyrosine phosphorylation. Competition with endogenous PKC-δ for NM1 and IGF-IR association by PKC-δK376R is probably an important mechanism underlying the PKC-δK376R-mediated inhibition of cell transformation by NM1 and IGF-IR.


1998 ◽  
Vol 273 (40) ◽  
pp. 25961-25966 ◽  
Author(s):  
Yumiko Okubo ◽  
Vicky A. Blakesley ◽  
Bethel Stannard ◽  
Silvio Gutkind ◽  
Derek Le Roith

2002 ◽  
Vol 277 (18) ◽  
pp. 15261-15270 ◽  
Author(s):  
Yutaka Umayahara ◽  
Yoshitaka Kajimoto ◽  
Yoshio Fujitani ◽  
Shin-ichi Gorogawa ◽  
Tetsuyuki Yasuda ◽  
...  

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