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MEMP - Thesis Defense - Or Gadish

Friday, May 10, 2019

Integrated platform for mapping endothelial kinase and phosphatase pathways to cytoskeletal functional changes

Endothelial cells (EC) are critical to the tumor ecosystem, lining the blood vessels that control nutrient transport while also regulating homeostasis. Normalization of vessel structure, and by extension, EC state, has shown clinical promise. We studied the functional and phosphorylative transformations of EC state in cancer to elucidate further targets for EC normalization.
ECs cultured in breast cancer cell conditioned media displayed marked elongation and impaired wound healing. Given the well-established relationship between cytoskeletal reorganization and phosphorylative regulation, we estimated kinase and phosphatase activity by quantifying phosphorylation of downstream targets using mass spectrometry. Of the 152 kinases and phosphatases analyzed across 62 phosphoenzyme families, 22 families were categorized as significant drivers of dysfunction, and 5 as normalizers. We used inhibitors to functionally validate seven of the most significant in morphology and wound healing. The most promising candidate target for normalization was Akt, whose inhibition restored the control phenotype in both assays. Counter to much of the literature, Src activity was decreased in cancer-conditioned transformation and Src inhibition in control cells induced a dysfunctional phenotype.
These data prompt further investigation of Akt and caution with regard to Src as targets for inducing cancer homeostasis. Beyond identifying specific targets, this work presents a new framework that maps functional changes to phosphoenzyme drivers, which can be readily applied to other models. This comprehensive library of phosphoenzyme activity developed will shed light on how existing cancer-targeting inhibitors affect tumor endothelium.

Thesis Supervisors:
Elazer R. Edelman, MD, PhD
Edward J. Poitras Professor, Institute for Medical Engineering & Science, Massachusetts Institute of Technology; Professor of Medicine, Harvard Medical School

Natalie Artzi, PhD
Assistant Professor of Medicine, Harvard Medical School
Thesis Committee Chair:
Sangeeta N. Bhatia, MD, PhD
John J. (1929) and Dorothy Wilson Professor, Institute for Medical Engineering & Science,  Electrical Engineering & Computer Science, Massachusetts Institute of Technology
Thesis Reader:
Shiladitya Sengupta, MD, PhD
Assistant Professor of Medicine and Health Sciences & Technology, Harvard Medical School


Date and Time: 
Friday, May 10, 2019 - 9:30am to 11:30am

MIT 56-114