Enhancing cell surface expression of cytokine receptor CXCR4 to promote neural stem cell migration towards brain tumor (glioma) cells.
Authors:
Rohith Nayak, Pablo RomanoMentors:
- Michael Barish, Chair of Neurosciences, City of Hope
- Nousha Khosh, Research Associate II, City of Hope
Glioblastoma Multiforme (GBM) is a fatal intracranial tumor, accounting for more than 70% of brain cancers. The inevitable recurrence of GBMs following surgical resection of the tumor mass is due to the few remaining tumor cells which migrate and form new tumor foci. Neural stem cells (NSCs) possess a remarkable inherent tumor tropism and target and engulf GBM cells in vivo, which make them a viable potential delivery vehicle for GBM therapeutics. This project focuses on investigating clinically acceptable techniques to increase the efficiency of NSC-GBM interactions by upregulating CXCR4 surface protein expression. Two immortalized human NSC lines were utilized in this study; both lines were subjected to varying growth media and compounds previously reported to upregulate CXCR4 expression in other stem cell populations. The first experiment included adapting NSCs to grow in a serum free media specially constituted for NSCs. The next two experiments consisted of subjecting NSCs to varying doses of valproic acid (VPA) and prostaglandin E2 (PGE2). These cells were then analyzed for cell surface proteins using specific antibodies and evaluated by fluorescence microscopy and flow cytometry. As the cells were moved to a neural stem cell constituted media, they began to form neurospheres, an agglomeration of cells in suspension, but showed no increase in CXCR-4. The VPA assays also yielded a negative result – no discernable increase of CXCR-4 expression. The PGE2 assay resulted in a slight increase in CXCR-4 expression as seen by immunocytochemistry and is still being analyzed via flow cytometry. These results suggest that the serum free media cause these cells to return to a more stem-like phenotype, which is useful for growing cells in a larger quantity. The PGE2 assays are slightly promising, but further examinations are required. In the future, these results may have a significant effect on GBM therapies.