Mohamad Adada | Renaissance School of Medicine at Stony Brook University

Mohamad Adada
B.S. American University of Beirut, 2008

8th Year MSTP
4th year Molecular & Cellular Biology Medical Student

Advisor: Lina Obeid, M.D., Dean of Research, Stony Brook University

Department: Medicine

Graduate Program: Molecular & Cellular Biology

Title: Epidermal growth factor-induced cellular invasion requires sphingosine-1-phosphate/sphingosine-1-phosphate 2 receptor-mediated ezrin activation

Abstract:

Ezrin, radixin, and moesin (ERM) proteins link cortical actin to the plasma membrane, and coordinate cellular events that require cytoskeletal rearrangement, including cell division, migration, and invasion. While ERM proteins are involved in many important cellular events, the mechanisms regulating their function are not completely understood. Our laboratory previously identified reciprocal roles for the bioactive sphingolipids ceramide and sphingosine-1-phosphate (S1P) in the regulation of ERM proteins. We recently showed that ceramide-induced activation of PP1a leads to dephosphorylation and inactivation of ERM proteins, while S1P, the product of sphingosine kinase (SK), results in their phosphorylation and activation. Following these findings, we aimed to examine known inducers of the SK/S1P pathway, and evaluate their ability to regulate ERM proteins and invasion. We examined EGF, a known inducer of the SK/S1P pathway, for its ability to regulate ERM proteins.

SK was inhibited using siRNA technology as well as two different pharmacological inhibitors, ski-II and SK-X. S1P receptors (S1PR) were inhibited using pharmacological inhibitors and genetic knockdown approaches. Phosphomimetic (T567D) and nonphosphorylatable (T567A) ezrin constructs were used as a dominant active and negative forms respectively. Lamellipodia were examined using confocal microscopy. Cell invasion was assessed using Matrigel transwell assays.

We found that EGF induces ERM C-terminal threonine phosphorylation via activation of the SK/S1P pathway. We determined that EGF induces ERM phosphorylation via activation of S1PR2. In addition, EGF led to cell polarization in the form of lamellipodia, and this occurred through a mechanism involving S1PR2-mediated phosphorylation of ezrin T567. EGF-induced cellular invasion was also found to be dependent on S1PR2-induced T567 ezrin phosphorylation such that S1PR2 inhibition and expression of a dominant-negative ezrin mutant prevented cellular invasion toward EGF.

In this work, a novel mechanism of EGF-stimulated invasion is unveiled, whereby S1Pmediated activation of S1PR2 and phosphorylation of ezrin T567 is required. This new mechanism will open up new avenues in treating EGF-driven cancers that are not responsive to EGFR antagonists alone by a dual or a triple therapy, which can also involves the inhibition of SK and S1PR2.

Awards:
Inducted into the AOA Medical Honor Society, Stony Brook Chapter 2016

Travel Award for the 8th International ceramide 2015 conference (Cesame, Turkey)
Winner of the Distinguished Travel Award 2014 presented by Stony Brook University graduate school as a recognition of the applicant's outstanding scholarship and the impact of his work for both within his field and academia.

Nominee and recipient of a full membership in AAAS (The American 2014 Association for the Advancement of Science) for two years in support of the AAAS/Science Program for Excellence in Science by the Dean of Medicine at Stony Brook University Kenneth Kaushansky.

Publications:
(MSTP-supported publications indicated with an *)

Yang K, Adada M, Yell L, Sherman M, Alam A. (2016). Thyroid storm following lithium removal via hemodialysis. The primary care companion for CNS disorders. In press
Adada, M., Luberto, C., & Canals, D. (2016). Inhibitors of the sphingomyelin cycle: Sphingomyelin synthases and sphingomyelinases. Chem Phys Lipids, 197, 45-59. doi: 10.1016/j.chemphyslip.2015.07.008
Salama, M. F., Carroll, B., Adada, M., Pulkoski-Gross, M., Hannun, Y. A., & Obeid, L. M. (2015). A novel role of sphingosine kinase-1 in the invasion and angiogenesis of VHL mutant clear cell renal cell carcinoma. FASEB J, 29(7), 2803-2813. doi: 10.1096/fj.15-270413
Espaillat, M., Shamseddine, A., Adada, M., Hannun, Y. A., & Obeid, L. M. (2015). Ceramide and sphingosine-1-phosphate in cancer, two faces of the sphinx. Translational Cancer Research, 4(5), 484-499. doi: 10.3978/j.issn.2218- 676X.2015.10.01
Hernandez-Corbacho, M. J., Canals, D., Adada, M. M., Liu, M., Senkal, C. E., Yi, J. K., . . . Obeid, L. M. (2015). Tumor Necrosis Factor-alpha (TNFalpha)- induced Ceramide Generation via Ceramide Synthases Regulates Loss of Focal Adhesion Kinase (FAK) and Programmed Cell Death. J Biol Chem, 290(42), 25356-25373. doi: 10.1074/jbc.M115.658658
Adada, M. M., Canals, D., Jeong, N., Kelkar, A. D., Hernandez-Corbacho, M., Pulkoski-Gross, M. J., . . . Obeid, L. M. (2015). Intracellular sphingosine kinase 2-derived sphingosine-1-phosphate mediates epidermal growth factor-induced ezrin-radixin-moesin phosphorylation and cancer cell invasion. FASEB J, 29(11), 4654-4669. doi: 10.1096/fj.15-274340
Adada M, Orr-Gandy KA, Snider AJ, Canals D, Hannun YA, Obeid LM, Clarke CJ. Sphingosine Kinase 1 (SK1) regulates Tumor Necrosis Factor (TNF)-mediated RANTES Induction Through p38 MAPK but Independently of NF-?B Activation. J Biol Chem. 2013 Aug 9.

Adada M, Canals D, Hannun YA, Obeid LM. Sphingosine-1-phosphate receptor 2. FEBS J. 2013 Jul 24. doi: 10.1111/febs.12446.

Adada M, Canals D, Hannun YA, Obeid LM. Sphingolipid regulation of ezrin, radixin, and moesin proteins family: Implications for cell dynamics. Biochim Biophys Acta. 2013 Jul 12. doi:pii: S1388 1981(13)00140-6. 10.1016/j.bbalip.2013.07.002.

Orr Gandy KA*, Adada M * , Canals D, Carroll B, Roddy P, Hannun YA, Obeid LM. Epidermal growth factor-induced cellular invasion requires sphingosine-1-phosphate/sphingosine-1-phosphate 2 receptor- mediated ezrin activation. FASEB J. 2013 Aug;27(8):3155-66. doi: 10.1096/fj.13-228460. Epub 2013 Apr29.

* These authors contributed equally to the work

Co-Author Publications:

Perry DM, Newcomb B, Adada M, Wu BX, Roddy P, Kitatani K, Siskind L, Obeid LM, Hannun YA. Defining a role for acid sphingomyelinase in the p38/interleukin-6 pathway. J Biol Chem. 2014 Aug 8;289(32):22401-12. doi: 10.1074/jbc.M114.589648.

El Osta M, Liu M, Adada M, Senkal CE, Idkowiak-Baldys J, Obeid LM, Clarke CJ, Hannun YA. Sustained PKCßII activity confers oncogenic properties in a phospholipase D-and mTOR-dependent manner. FASEB J. 2014 Jan;28(1):495-505. doi: 10.1096/fj.13-230557.

Gandy KA, Canals D, Adada M, Wada M, Roddy P, Snider AJ, Hannun YA, Obeid LM. Sphingosine 1 phosphate induces filopodia formation through S1PR2 activation of ERM proteins. Biochem J. 2013 Feb 1;449(3):661-72. doi: 10.1042/BJ20120213.