Abstract B23: Characterization of canine glioma cancer stem cells for human glioblastoma models

Glioblastoma (GBM) is the most aggressive and common form of glioma in humans with an average survival period of twelve to fourteen months. Due to its highly invasive and malignant nature, current treatment options have not been able to improve the survival rate over the past several decades. Several studies claim that cancer stem cells (CSC), self-renewalable and differentiable into neuron- and glia-like cells, may play a key role in initiating tumor formation and cancer reoccurrence. Cancer stem cells are known to have tumorigenic ability and resistance to current cancer treatment options. Similar to humans, naturally occurring glioma in canines is highly common and devastating. Cancer in canines and humans shares strong anatomical and physiological similarities, including histological appearance, tumor genetics, molecular targets, biological behavior, and response to therapies. The goal of this study is to characterize and test the presence of canine glioma cancer stem cells (CSC) in order to utilize the spontaneously occurring cancer models to deepen understanding of human and canine GBM cancer stem cells and investigate better cancer model systems utilizing naturally occurring canine glioma since artificial rodent models have not been able to translate into human GBM studies effectively. Two different canine glioma cells lines, Roxanne and Ike, were harvested and provided from the College of Veterinary Medicine Small Animal Hospital at Purdue University. Canine cell line Roxanne, Grade II Oligodendroglioma, was harvested from a six-year-old female mixed breed by post-mortem examination. The second canine cell line Ike, Grade II Oligodendroglioma neoplastic cells with negative GFAP expression, was harvested from a six-year-old male Boxer by surgery. In order to compare these canine cell lines with the human GBM cancer stem cells GBAM1 human GBM stem cell line (known to be 98% CD133 positive) was obtained from Moffitt Cancer Center. These three cell lines were investigated by immunofluorescence with CD133, sex determining region Y-box 2 (Sox2), Notch1, glial acidic fibrillary protein (GFAP), and O6-alkylguanine DNA alkyltransferase (MGMT) protein markers. Cells were fixed and permeabilized prior to antibody attachment. Confocal images for detection of CD133, Sox2, Notch, GFAP, and MGMT were taken with a Nikon A1R-MP confocal microscope equipped with an objective Plan Fluor 20X-oil/water (0.75 NA). Roxanne and GBAM1 were tested for immunofluorescence since Ike was not able to grow confluent in in vitro environment. GBAM1 expressed all protein markers, CD133, Sox2, Notch, and MGMT, except for GFAP from the immunofluorescent detection. However, canine Roxanne only expressed Sox2 proteins, which is a transcription factor for undifferentiated stem cell. Other immunofluorescent signals were either weak or not expressed. Since the cancer stem cell population is very low in heterogeneous glioma tumor environment, it was difficult to conclude the presence of these protein markers in canine samples. In order to validate and further explore these results, western blot will be performed in the three cell lines. Characterization of both human and canine cancer stem cells has a potential to provide a better understanding of both human and canine glioma cancer stem cells, improve an animal cancer model system, and develop more effective treatments for glioblastoma. Citation Format: Soo Jung Ha, Marisol Herrera-Perez, Jiri Adamec, R. Timothy Bentley, Jenna L. Rickus, Kari L. Clase. Characterization of canine glioma cancer stem cells for human glioblastoma models. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr B23.