Genome Engineering Evolves Brain Tumor Modeling

Abstract

Genome engineering using programmable nucleases such as transcription activator-like effector nuclease (TALEN), and clustered regularly interspaced short palindromic repeat-associated protein nine facilitated the introduction of genetic alterations at specific genomic sites in various cell types. These tools have been applied to cancer modeling to understand the pathogenic effects of the growing catalog of mutations found in human cancers. Pertaining to brain tumors, neural progenitor cells derived from human induced pluripotent stem cells (iPSCs) engineered with different combinations of genetic driver mutations observed in distinct molecular subtypes of glioblastomas, the most common form of primary brain cancer in adults, give rise to brain tumors when engrafted orthotopically in mice. These glioblastoma models recapitulate the transcriptomic signature of each molecular subtype and authentically resemble pathobiology of glioblastoma, including inter-and intra-tumor heterogeneity, chromosomal aberrations, and extrachromosomal DNA amplifications. Similar engineering with genetic mutations found in medulloblastoma and atypical teratoid rhabdoid tumors in iPSCs have led to genetically trackable models that bear clinical relevance to these pediatric brain tumors. These models have contributed to improved comprehension of the genetic causation of tumorigenesis and offered a novel platform for therapeutic discovery. Studied in the context of three-dimensional cerebral organoids, these models have aided in the study of tumor invasion as well as therapeutic responses. In summary, modeling brain tumors through genome engineering enables not only the establishment of authentic tumor avatars driven by bona fide genetic mutations observed in patient samples but also facilitates functional investigations of particular genetic alterations in an otherwise isogenic background.

Pioneering models of pediatric brain tumors

“…Genome engineering using CRISPR/Cas9 contributed to the flexibility of tumor modeling with the feasible introduction of bona fide genetic alterations observed in patient tumors [108] . Single-cell RNA-sequencing of adult glioblastoma models derived from human induced pluripotent stem cells (iPSCs) demonstrated that these models recapitulate inter- and intra-tumor heterogeneity observed in glioblastoma patient samples [109] .…”

Friends with Benefits: Chemokines, Glioblastoma-Associated Microglia/Macrophages, and Tumor Microenvironment

“…The utility of gene editing for GBM knowledge advancement has been solidly argued in human cell lines and organoid models [ 273 ], as well as animal models (for details on the genome engineering tools and models used, see [ 274 ]). It is continuously used for various purposes, such as screening for therapeutic targets or generation of cellular models and accurate animal disease models.…”

Applications of CRISPR-Cas9 Technology to Genome Editing in Glioblastoma Multiforme

“…Besides its role in developing novel models for GBM as reviewed recently [ 104 ], CRISPR-Cas9 technology has offered novel insights into the unique and redundant roles of various genes in regulating proliferation, stemness, angiogenesis, and invasion of GBM cell lines, providing us promising therapeutic targets to treat or halt progression of this malignant disease. One of the major challenges of using this technology appeared obvious that viral Cas9 components were used in large number of GBM research, and this strategy could result in off-target editing and undesirable mutations.…”