High-grade glioma is an aggressive cancer that occurs naturally in pet dogs. Canine high-grade glioma (cHGG) is treated with radiation, chemotherapy or surgery, but has no curative treatment. Within the past eight years, there have been advances in our imaging and histopathology standards as well as genetic charactereization of cHGG. However, there are only three cHGG cell lines publicly available, all of which were derived from astrocytoma and established using methods involving expansion of tumour cells in vitro on plastic dishes. In order to provide more clinically relevant cell lines for studying cHGG in vitro, the goal of this study was to establish cHGG patient-derived lines, whereby cancer cells are expanded in vivo by injecting cells into immunocompromized laboratory mice. The cells are then harvested from mice and used for in vitro studies. This method is the standard in the human field and has been shown to minimize the acquisition of genetic alterations and gene expression changes from the original tumour. Through a multi-institutional collaboration, we describe our methods for establishing two novel cHGG patient-derived lines, Boo-HA and Mo-HO, from a high-grade astrocytoma and a high-grade oligodendroglioma, respectively. We compare our novel lines to G06-A, J3T-Bg, and SDT-3G (traditional cHGG cell lines) in terms of proliferation and sensitivity to radiation. We also perform whole genome sequencing and identify an NF1 truncating mutation in Mo-HO. We report the characterization and availability of these novel patient-derived lines for use by the veterinary community.
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cHGG is an aggressive disease with no cure. There are three cell lines available in the literature for studying cHGG in the laboratory, however, these lines are all derived from astrocytoma primary tumours. Within this study we sought to increase the number and types of cHGG lines available by creating patient-derived lines, which require in vivo expansion of cancer cells. Patient-derived lines are cultured in tissue culture medium supplemented with growth factors shown to promote the presence of cancer stem-cell like tumour cells.13 In addition, the medium lacks serum, which has been shown to alter the genome and transcriptome of cancer cells.9 Herein, we report the establishment and characterization of two novel cHGG patient-derived lines, Mo-HO and Boo-HA. Additionally, we share our workflow and methods (see Supplemental Text for expanded methods) that enabled us to generate these lines using resources across different institutions. At Ohio State University Veterinary Medical Center, our standard of care for treating cHGG is radiation, therefore, our only opportunity to obtain cHGG tissue samples is during necropsy after owner elected euthanasia, and even then, the tissues are presumptive cHGG based on imaging until histopathology can be performed. Although we were not able to obtain samples via necropsy post euthanasia, it is another source of tumour tissue that should continue to be explored to increase the number of cHGG patient-derived lines available. Because our approach was successful with overnight shipping of tumour cells to a lab at another institution, we hope our methods will provide a guide to enable scientists and clinicians with unique expertise across different institutions to establish more cHGG patient-derived lines. When characterizing the growth and sensitivity to radiation of our novel patient-derived lines, we also included the commonly used cHGG cell lines G06-A, J3T-Bg and SDT-3G. These cell lines were established using traditional methods in medium containing fetal bovine serum and devoid of growth factors. Because our goal was to provide a comparison for the veterinary community to reference when deciding which cells to use, we cultured G06-A, J3T-Bg and SDT-3G using the medium in which they were established. Therefore, the differences in medium between patient-derived lines and traditionally established lines may contribute to the differences in cell growth and sensitivity to radiation reported here. One technical challenge we did encounter in mice being monitored for cHGG cell growth after injection of cells IC was a lack of tumour enhancement post Gd-based contrast imaging (Figure 3). Engrafted cHGG cell growth was evident when tumours were large, mostly due to changes in brain anatomy, such as midline shift. Since our goal with the intracranial injections was to expand the cell number as much as possible, we did not need to detect small tumours so the imaging was sufficient for our studies. However, future work establishing similar lines may benefit from incubating supramagnetic ion oxide (SPIO) particles with cHGG cells prior to IC injection. SPIO particles give a ‘negative’ contrast in MRI, appearing as hypointense regions on MR images, allowing for more refined monitoring of tumour growth. In conclusion, we report two novel cHGG patient-derived lines, Boo-HA and Mo-HO, the latter of which is the first published cell line of canine oligodendroglioma. Further study of these two lines will be needed to validate and establish their clinical and translational relevance.
© 2023 The Authors. Veterinary and Comparative Oncology published by John Wiley & Sons Ltd.
- canine brain cancer
- canine high-grade glioma
- canine oligodendroglioma
- patient-derived line
PubMed: MeSH publication types
- Journal Article