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KMID : 0613820020120020164
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Journal of Life Science
2002 Volume.12 No. 2 p.164 ~ p.172
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Polyamines Modulate Growth Factor-Induced Membrane Protein Phosphorylation in MCF-7 Human Breast Cancer Cells
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Lee Ji-Young
Kim Ji-Hyun
Lee Kyung-Hee
Kim Byeong-Gee
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Abstract
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Breast cancer cell lines display a wide variety of growth factor receptors, and considerable evidences implicate the importance of signalings from those receptors. A useful prognostic indicator would be the level of activity of a second messenger protein used in common by these receptors. Our studies were designed to obtain preliminary information on the possible role of polyamine as a mediator of the membrane-associated protein phosphorylation and as a regulator of second messenger in mitogenic signal of estrogen or growth factors in MCF-7 human breast cancer cells. DFMO significantly inhibited the phosphorylation induced by E₂, TGF-α and EGF in membrane-associated proteins (154, 134, 116, and 104 kDa). Exogenous polyamines abolished the inhibitory effect of DFMO. Tyrosine phosphorylations of membrane-associated proteins were not increased by E₂ or growth factor treatments and not affected DFMO treatment. Polyamine administration markedly enhanced the tyrosine phosphorylation of membrane-associated proteins (154, 134, and 116 kDa). In the present study, E₂ and TGF-α and EGF enhanced protein phosphorylation in the almost same levels. These data indicate that E₂ and growth factor signaling pathway may cross-talk through various protein kinase which phosphorylated many substrate proteins (154, 134, 116 and 104 kDa). Polyamines may be involved in growth signaling pathway of E₂ and TGF-α or EGF for the cross-talk through regulation of the protein phosphorylation such as 154, 134, 116 and 104 kDa. Polyamine may also selectively interfere with several different protein kinases, and the specific steps in signal transduction system were effected by polyamines.
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KEYWORD
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E2, EGF, Membrane, Polyamines, TGF-α
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