Quantitative Analysis of Tumor-induced Intracellular Signaling Networks

Open Access
Author:
Weidert, Eric Randall
Area of Honors:
Bioengineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Cheng Dong, Thesis Supervisor
  • Peter J Butler, Honors Advisor
  • Reka Z Albert, Faculty Reader
Keywords:
  • melanoma
  • Boolean modeling
  • kinetic modeling
  • E-selectin
  • PAK
  • junction disassembly
  • contractility
Abstract:
Metastasis of tumor cells is a complex process that involves adhesion and extravasation of tumor cells (TCs) in the surrounding environment. The adhesion of TCs is mediated by adhesion molecules on both the endothelial cell and TC, along with chemokine secretion. A series of events involving breakdown of the endothelial junctions regulated by vascular endothelial (VE)-Cadherin disassembly and contraction of the endothelial cells via actin filament remodeling and actinomyosin contraction forces increases the permeability of the endothelium allowing for extravasation. Previously, our lab has shown that the vascular adhesion molecule (VCAM)-1 receptor on the endothelial cell and inflammatory cytokines IL-8 and IL-1β are important candidates for tumor-induced endothelial gap formation. In this study, two more endothelial receptors, E-selectin and P-selectin, were investigated to see if they too were important mediators of tumor-induced gap formation. Both were found not to be influential players in gap formation. A signaling network was then constructed with the lab’s three known inputs and their downstream signaling cascades to better understand their contribution to the three causes of endothelial junction breakdown. The network was translated into two different types of models: Boolean and kinetic, in hopes that studying the signaling dynamics quantitatively in two different manners will give insights and validations to which inputs and outputs are most influential in gap formation. Both are dynamic models, but Boolean modeling focuses on the organization of the signaling network as opposed to kinetic modeling which focuses on the kinetic details of the individual interactions. It was determined that VCAM-1 was the most dominant input and actinomyosin contractility, through phosphorylation of myosin light chain (MLC), was the most important output. The kinetic model paired with experimental approaches was further used to evaluate the role of VCAM-1 on the phosphorylation of p38 and VE-Cadherin. It was found that the activation rates of PAK amplify the phosphorylation rates of p38 and VE-Cadherin.