Introduction: Glioblastoma multiforme (GBM), the most common primary brain malignancy in adults, carries a grim prognosis, with poor response to current pharmacotherapy and rapid recurrence following resection. Glioblastoma cancer stem cells (GSCs), a subpopulation of tumor cells with capacities for self-renewal and tumor initiation, are resistant to many drug therapies and offer a possible explanation for the failings of current treatments. Given the unique characteristics of GSCs and the therapeutic challenges they pose, it is critical to develop therapies specifically tailored to the idiosyncrasies of these cells.
Methods: We performed a genome-wide siRNA screen in order to identify genes associated with decreased cell viability, gross changes in cell morphology, and decreases in expression of the stem cell marker nestin in a GSC cell line. Based on the results of this screen, a number of genes were selected for follow-up studies, particularly those genes associated with a reduction in the number of viable cells. The effects of siRNA knockdown of these genes were verified in several cell lines by lipid-mediated transfection and quantification of cell viability.
Results: Genome-wide screening identified 7 genes associated with reduction in cell viability. Of those, UBC, CCNB1, TPX2, WEE1, and DVL2 were selected for follow up studies. siRNA knockdown of these genes resulted in decreased cell viability in several genetically distinct cell lines. Further siRNA treatment produced a significant reduction in cell viability when coupled with temozolomide treatment, compared to temozolomide therapy alone.
Conclusions: Based on these studies, we have identified several target genes that, when knocked down by siRNA transfection, result in decreased viability of GSCs. Given recent advances in the delivery of siRNA therapies in the form of nanocarrier delivery systems, these targets represent a viable treatment option in targeting GSCs.
Patient Care: Identification of therapeutic targets specific to glioblastoma stem cells is critical in the development of effective therapies in treating glioblastoma.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the challenges GSCs pose in developing effective treatments for GBM, 2) Understand the promise and challenges of developing effective siRNA therapies, and 3) Identify several new therapeutic targets in the treatment of GSCs.