Thu, 21 Aug 2008 05:33:38 BST CiteULike: eckart_bindewald akt http://www.citeulike.org/user/eckart_bindewald/tag/akt CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/eckart_bindewald/article/2580541 <i>Mol Cancer Res, Vol. 1, No. 6. (1 April 2003), pp. 475-484.</i><br /><br />To determine which genes may be regulated by Akt and participate in the transformation of cells, we have examined by microarray analyses genes turned on in the prostate cancer cell line, PC3, when Akt activity was induced. PC3 cells, which lack the lipid phosphatase PTEN, were treated overnight with a reversible inhibitor of the phosphatidylinositol 3-kinase, LY294002 (a treatment which was found to reversibly decrease Akt enzymatic activity). The inhibitor was then washed out and mRNA collected 2, 6, and 10 h later and compared by microarray analyses with mRNAs present immediately after removal of the inhibitor. One of the identified induced mRNAs, Fra-1, was further studied by transient transfections of a reporter construct containing its 5' regulatory region. This construct was found to be directly induced 4- to 5-fold by co-transfection with constitutively active Akt3 but not kinase dead Akt. The regulation by Akt3 was found to be due to two specific regions in the Fra-1 regulatory sequence which match Sp1 consensus sites. Finally, gel shift studies showed that the binding of Sp1 to one of these sites was dependent on the PI 3-kinase pathway. These results indicate that LY294002 treatment and washout is a useful method to study the activation of Akt in the context of a tumor cell. Moreover, the identification of Fra-1 as an Akt-regulated gene may have implications for the ability of Akt to transform cells since Fra-1 has been implicated in cell growth and the aggressiveness of tumors. Gene Expression Profiling in Prostate Cancer Cells With Akt Activation Reveals Fra-1 As an Akt-Inducible Gene Gunjan Tiwari Hiroshi Sakaue Jonathan Pollack Richard Roth Mol Cancer Res, Vol. 1, No. 6. (1 April 2003), pp. 475-484. 2008-03-24T13:59:32-00:00 2003 Mol Cancer Res 1 6 475 484 akt cancer expression gene induction microarray profile http://www.citeulike.org/user/eckart_bindewald/article/935652 <i>Mol Cell, Vol. 12, No. 4. (October 2003), pp. 889-901.</i><br /><br />In order to determine the global effects of oncogenic Ras and Akt signaling pathways on translational efficiencies, we compared the gene expression profiles of total cellular mRNA and mRNA associated with polysomes. We found that the immediate effect of Ras and Akt signaling blockade on transcription was relatively modest; however, the profile of mRNA associated with polysomes was substantially altered. These observations indicate that the immediate effect of Ras and Akt signaling regulates the recruitment of specific mRNAs to ribosomes to a far greater extent than they regulate the production of mRNAs by transcriptional effects. The mRNAs most affected are those encoding proteins that regulate growth, transcription regulation, cell to cell interactions, and morphology. These data support a model whereby Ras and Akt signaling primarily lead to cellular transformation by altering the transcriptome and producing a radical shift in the composition of mRNAs associated with actively translating polysomes. Oncogenic Ras and Akt signaling contribute to glioblastoma formation by differential recruitment of existing mRNAs to polysomes. VK Rajasekhar A Viale ND Socci M Wiedmann X Hu EC Holland Mol Cell, Vol. 12, No. 4. (October 2003), pp. 889-901. 2006-11-07T18:29:42-00:00 2003 Mol Cell 1097-2765 12 4 889 901 akt initiation ras translation translation_initiation