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Clarissa Martins

Scholar: Clarissa Martins

Clarissa Martins

Major: Biochemistry and Molecular Biology

Faculty Mentors: Dr. Keith Kikawa

Research Topic: Linoleic Acid Supplementation Upregulates Phosphatidylinositol-3-kinase Signaling by Increasing the Association Between Gab1 and EGFR

Abstract:

The omega-6 polyunsaturated fatty acid, linoleic acid (LA), is prevalent in Western diets and is known to enhance the tumorigenesis of mammary cancer models; with previous work demonstrating an upregulation of phosphatidylinositol-3-kinase (PI3K) signaling may play a key role.  In this study, a mechanism for LA's upregulation of cancer cell growth is defined.  High levels of LA in animal diets or cell culture medium initiates a series of events beginning with increased cyclooxygenase (COX) activity, which leads to increased prostaglandin E2 (PGE2) production, that activates the STAT3 transcription factor and subsequently matrix metalloproteinase levels responsible for upregulating transforming growth factor alpha (TGF-α).  TGF-α is a classic growth factor for the epidermal growth factor receptor 1 (EGFR), which plays a role in a large number of cancers.  The Grb2-associated binding protein 1 (Gab1) is a scaffolding protein that can complex with EGFR to activate PI3K signaling.  Recent studies in our laboratory reveal LA supplementation of the breast cancer cell lines MDA-MB-231 and BT-474 greatly increases the association between Gab1 and EGFR, while at the same time dramatically decreasing Gab1 protein levels.  These changes are concomitant with increases in activated Akt (pAkt), a downstream signaling component in the PI3K signaling pathway.  Moreover, inhibitors of EGFR and Gab1-specific siRNAs are capable of reversing LA-induced upregulation of pAkt, as well as observed increases in cell proliferation for these models.  Finally, we were able to confirm these findings in the A549 lung cancer cell line, validating the potential relevance to tissues other than breast cancer cell lines.  These data establish Gab1 as major target in LA-induced enhancement of tumorigenesis.

New Scholar: 2012 cohort

Graduating With Baccalaureate Degree: 2013

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