Type
Text
Type
Dissertation
Advisor
Seeliger, Markus | Miller, W. Todd | Seeliger, Jessica | El-Maghrabi, Raafat | Brown, Deborah.
Date
2015-12-01
Keywords
Biochemistry -- Biology | Brk, cancer, macrocycles, Src, Srms, tyrosine kinases
Department
Department of Molecular and Cellular Biology
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/76463
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Dysregulation in the enzymatic activity of Src-family kinases (SFKs) is implicated in multiple disease states, including cancer. SFKs have been intensely investigated as targets for cancer therapeutics. Achieving selectively among the SFKs, and other related non-receptor tyrosine kinases (nRTKs), has proven challenging due to the high similarity in their catalytic domains. Side effects arising from nonspecific binding are common in anticancer therapies, and underscore the need to identify, and exploit differences in these proteins to develop more specific inhibitors. In this study, we have identified differences between the regulatory partners of Src and Brk (Breast Tumor Kinase). We also discuss a novel class of Src inhibitors that demonstrated selectivity among the SFKs, and adaptability toward clinically relevant Src mutations. Src and Brk share similar autoregulatory mechanisms. They are both activated by autophosphorylation in the catalytic domain, and inhibited by C-terminal tyrosine phosphorylation. We have demonstrated specificity in the C-terminal kinases responsible for inhibiting these proteins. The Src-like nRTK Srms phosphorylated the C-terminus of Brk, but not Src; in contrast, Csk is the kinase responsible for C-terminal phosphorylation of Src, but not Brk. We have also found that the phosphatase PTP1B has opposing effects on the activity of these two kinases. PTP1B selectively deactivated Brk by dephosphorylating the activation loop (Tyr-342), but not Src. In contrast, PTP1B potentiated Src activity, by regulating the interaction between the anchor protein Cbp/Pag, and Csk. We also carried out experiments on macrocyclic peptides, a novel, and adaptive class of Src inhibitors. One key advantage these compounds possess over traditional inhibitors is the rotational freedom inherent in their backbone structure, which provides flexibility to adapt to mutations in the protein. Previously, two classes of macrocycles were reported that possessed high selectivity for Src, over other SFKs. In this study, we present crystallographic data to demonstrate how these compounds can adapt to clinically relevant drug-resistant mutations in Src. We also report a unique salt-bridge between one of the macrocycles and a catalytically critical residue of Src. Drug interactions with immutable residues as these are desirable for attenuating drug resistance in the clinic. | 179 pages
Recommended Citation
Aleem, Saadat, "Specificity in the Regulation and Inhibition of Src and Related Tyrosine Kinases" (2015). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 2383.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/2383