کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2803003 | 1156717 | 2010 | 9 صفحه PDF | دانلود رایگان |
It is known that all-trans retinoic acid (RA) is a useful therapeutic anticancer agent in breast cancer that acts by inducing apoptosis and growth inhibition. Insulin-like growth factor-I (IGF-I) is also known to be a growth hormone that plays an important role in cell proliferation and apoptosis. We examined the relationships between RA-induced protein kinase C (PKC)-δ, the secretion and synthesis of IGF-I, and oxidative stress. RA at 10−8 M and 10−7 M increased PKC-δ phosphorylation (the ratio of phosphorylated to total PKC-δ) (p < 0.05) and decreased the secretion and synthesis of IGF-I (p < 0.05) compared to control, with the effects peaking for treatment with 10−7 M RA for 72 h. The silencing of PKC-δ prevented the RA-induced inhibition of the secretion and synthesis of IGF-I and cell viability (p < 0.05). Application of 10−7 M RA for 72 h increased the level of thiobarbituric-acid-reactive substances and the expression of inducible nitric oxide synthase relative to control (p < 0.05). These increases were blocked by suppressing PKC-δ and by pretreatment with the antioxidants glutathione and diphenyleneiodonium (p < 0.05). These antioxidants also reversed the RA-induced inhibition of the secretion and synthesis of IGF-I and cell viability to control levels (p < 0.05). The effects of suppressing IGF-I demonstrate that IGF-I plays a critical role in the RA-induced inhibition of the cell viability. These results indicate that the anticancer effects of RA are mediated by inhibition of the secretion and synthesis of IGF-I, and involve a PKC-δ-dependent mechanism, and they provide evidence of an interaction between PKC-δ and reactive oxygen species.
Journal: Growth Hormone & IGF Research - Volume 20, Issue 2, April 2010, Pages 101–109