Development and Validation of a Glioblastoma Model System Using Receptor Tyrosine Kinases

Abstract

By Claire Burgoon, Neuroscience - Neurobiology Concentration

Advisor: David Plas

Presentation ID: 167

Abstract: Axl is a cell surface receptor tyrosine kinase (RTK) that is a major mediator of therapy resistance in Glioblastoma. Axl activation is controlled at the surface by the intracellular function of S6K2. In addition, Phosphatidylserine (PtS) plays an important role in signaling and activation of Axl through its ability to bind the Axl ligand Gas6. I developed a model system and a series of experiments were performed that tested the effects of S6K2 and PtS in Axl regulation at the cell surface. Non-targeting or sgS6K2 LN229 cells were transduced with a GFP control or Axl-GFP lentiviral construct. The cells were sorted to yield populations that express GFP at greater than 90%. Western blot was used to test the total protein of Axl in the GFP positive populations. Results showed that there was an overexpression of total Axl protein between control and Axl-transduced cells. Anti-Axl was used to test the surface expression of Axl by FACS, however there was no change in the cell surface expression of Axl control versus overexpressed cells nor in Annexin V. Axl is a major mediator in Glioblastoma therapy resistance and I used Glioblastoma LN229 cells to test S6K2's inhibition of the expression of Axl compared to sgS6K2. The cells were validated through western blot to test an overexpression of total Axl protein. However, through FACS analysis, the surface level of Axl expression did not change. Moving forward, to determine the level of Axl in all cellular compartments, Immunofluorescence is being established.