The epidermal growth factor receptor (EGFR) regulates proliferation, migration, apoptosis, and differentiation of cells. Many types of cancer have abnormally high EGFR activity that contributes to their growth, and studies have shown that inhibiting EGFR can reduce tumor size. We made diacylglycerol kinase (DGK) delta knockout mice and discovered that by regulating protein kinase C enzymes, DGKdelta modulates the expression and activity of EGFR. This proposal has three aims that will help us understand how DGKdelta regulates EGFR signaling and will test the potential anti-tumor effects of disrupting the function of DGKdelta.
In Aim 1, we will determine how DGKdelta modulates EGFR expression. We found enhanced EGFR ubiquitination and increased PKC activity in DGKdelta deficient cells. Additionally, we discovered that PKCalpha is required for proper EGFR ubiquitination. Together, these data led us to hypothesize that DGKdelta regulates EGFR ubiquitination through PKCalpha. We will test this possibility in Aim 1. We also discovered that DGKdelta modulates EGFR activity independently of changes in EGFR expression. In DGKdelta deficient cells and tissues, we found enhanced phosphorylation of a threonine residue in EGFR. This phosphorylation is known to inhibit EGFR activity and our data indicate that PKCdelta is responsible. This led us to hypothesize that DGKdelta regulates EGFR activity by inhibiting PKCdelta phosphorylation of EGFR.
In Aim 2, we will test this possibility. Finally, in Aim 3, we will use cell culture and mouse xenograft models to test the impact on tumorigenesis of disrupting the function of DGKdelta. Collectively, our experiments will clarify how DGKdelta regulates EGFR signaling, will define the contribution of DGKdelta to tumor formation, and will measure the anti-tumor effects of disrupting the function of DGKdelta.

Public Health Relevance

EGFR is an important cancer target. We have found a novel way to regulate its expression and activity. These properties of EGFR are fundamentally important for it to promote cancer and our experiments might uncover new anti-cancer therapies. Thus, our proposal has important relevance to public health. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
2R01CA095463-06A2
Application #
7524983
Study Section
Cancer Etiology Study Section (CE)
Program Officer
Yassin, Rihab R,
Project Start
2002-04-25
Project End
2012-07-31
Budget Start
2008-09-01
Budget End
2009-07-31
Support Year
6
Fiscal Year
2008
Total Cost
$269,443
Indirect Cost
Name
University of Utah
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
009095365
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112
Nakano, T; Iravani, A; Kim, M et al. (2014) Diacylglycerol kinase ? modulates oncogenic properties of lung cancer cells. Clin Transl Oncol 16:29-35
Ozaltin, Fatih; Li, Binghua; Rauhauser, Alysha et al. (2013) DGKE variants cause a glomerular microangiopathy that mimics membranoproliferative GN. J Am Soc Nephrol 24:377-84
Crotty, Tracy M; Nakano, Tomoyuki; Stafforini, Diana M et al. (2013) Diacylglycerol kinase ? modulates Akt phosphorylation through pleckstrin homology domain leucine-rich repeat protein phosphatase 2 (PHLPP2). J Biol Chem 288:1439-47
Shulga, Yulia V; Loukov, Dessi; Ivanova, Pavlina T et al. (2013) Diacylglycerol kinase delta promotes lipogenesis. Biochemistry 52:7766-76
Shulga, Yulia V; Anderson, Richard A; Topham, Matthew K et al. (2012) Phosphatidylinositol-4-phosphate 5-kinase isoforms exhibit acyl chain selectivity for both substrate and lipid activator. J Biol Chem 287:35953-63
Shulga, Yulia V; Topham, Matthew K; Epand, Richard M (2011) Substrate specificity of diacylglycerol kinase-epsilon and the phosphatidylinositol cycle. FEBS Lett 585:4025-8
Shulga, Yulia V; Topham, Matthew K; Epand, Richard M (2011) Study of arachidonoyl specificity in two enzymes of the PI cycle. J Mol Biol 409:101-12
Yang, Jinhee; Seo, Jinsoo; Nair, Ramya et al. (2011) DGK? regulates presynaptic release during mGluR-dependent LTD. EMBO J 30:165-80
Gantayet, Arpita; Jegatheswaran, Januvi; Jayakumaran, Gowtham et al. (2011) Endocannabinoids and diacylglycerol kinase activity. Biochim Biophys Acta 1808:1050-3
Cai, Jinjin; Crotty, Tracy M; Reichert, Ethan et al. (2010) Diacylglycerol kinase delta and protein kinase C(alpha) modulate epidermal growth factor receptor abundance and degradation through ubiquitin-specific protease 8. J Biol Chem 285:6952-9

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