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Show SPRING 2013 nence Undergraduate Research Program THE UNIVERSITY OF UTAH Overexpression of Aktl in epithelial cells changes directionality of cell extrusion Roselyn Neville1, Thomas Marshall2, Jody Rosenblatt2 department of Biology, University of Utah department of Oncological Sciences, Huntsman Cancer Institute Introduction Results Chemotherapies change extrusion More cells extrude basally in Aktl-GFP cells directionality in Akt-GFP cells a 0 Cells are removed from an epithelial layer to maintain the barrier function of the monolayer. This occurs through the contraction of an acto-myosin contractile ring. The localization of this ring determines the direction the cell extrudes. Cells that extrude apically go into the organ's lumen, but basal cells are extruded into underlying tissue. Usually apoptotic cells are extruded, but live cells are extruded as well. M a n y pro-survival signals are upregulaled in cancerous cells so that they m a y avoid apoptosis. One of the most crucial pathways that is deregulated in cancer cell is the PI3 kinase (PI3K)/Akt signaling pathway, which is a crucial downstream target of receptor tyrosine kinases that regulates many fundamental behaviors in the celL The activation of the Akt pathway can promote and inhibit different pathways for cell survival and apoptosis. This is important in cancer because the coordinated effects of different signaling pathways can control tumor . But the mechanisms of h o w this happens unclear. With this in mind we have hypothesized that extrusion is a potential mechanism through which the invading cell can first escape into the mesenchyme, and initiate metastasis. XIAPis a potential therapeutic target downstream of Akt I A F^M Extrusion and Directionality Conclusions Overexpression of Aktl causes more cells to I extrude basally. W h e n these cells are treated with Taxol, a c o m m o n chemotherapy, these rates do not {change, "this U important because Taxol is used to treat many different cancers, including those that j overexpress Akt. But Akt cannot be directly | targeted in cancer therapies since it's also crucial h normal cells. Therefore survival signals activated by Akt, in particular XIAP, are better downstream targets. X I A P is important in extrusion since Embelio has been shown to change the directionality of most cells from basal to apical. Future Directions We want to determine if this remains the same for Akt-GFP cells lacking XIAP. I've shown that a generic knockdown of XIAP decreases levels of XIAP on the third day after transduction. I will quantify the directionality of extrusion in these cells. Abo, I will determine whether or not cancerous cells and non-cancerous cells overcxpressiong Akt can survive after they have extruded. If these results indicate that there similar experiment will be done mouse to see if the results Acknowledgements i the n DOES OVEREXPRESSION OF AKT1 INDUCE INVASIVE BEHAVIOR IN EPITHELIAL CELLS? Roselyn Neville (Jody Rosenblatt) Department of Oncological Sciences Huntsman Cancer Institute University of Utah Metastasis is the primary cause of death in the majority of cancer patients. The American Cancer Society estimated that 571,950 people in the United States died from cancer in 2011, and 9 0% of these deaths were caused by metastasis [1,2]. Yet h o w this process initiates is not well under stood. Since metastasis greatly decreases a patient's likelihood for survival, a better under standing of the mechanisms that initiate metastasis could lead to better therapies for cancer patients. Our lab studies a novel process by which cells are removed from epithelia while maintaining the primary barrier function of the monolayer termed cell extrusion [4]. In this process, an extruding cell sends signals to surrounding cells that push-> the cell out of the monolayer while preventing any gaps from forming [4,6]. Cells can be removed in either the apical direction, towards the lumen of most organs, or basally into the underlying tissue. Usually, cells are extruded alive and then later die by apoptosis. Basal extrusion of cancer cells where cell death is blocked may provide a mechanism for cells to escape their primary sites in epithelia to initiate metastasis. I have found that overexpression of Aktl, a survival signal frequency upregulated in metastatic tumors [3,5], causes cells to extrude basally when cancer and non-cancer cell lines are stimulated to extrude using c o m m o n chemotherapies. I will also test whether cells over-expressing Aktl can survive after they are extruded, and how downstream targets of the Aktl pathway affect directionality of extrusion and cell survival. This project is important for determining if c o m m o n chemotherapies used on tumors overexpressing Aktl trigger invasion instead of their intended aim to shrink tumors. Understanding this process and the mechanisms through which it arises is vital for the study of cancer, and the future development of cancer therapies. |