Identifying a transcriptional core regulatory circuitry and other critical transcription factor dependencies in H3.3 G34R/V high-grade glioma

项目总结

Project Summary Pediatric high-grade gliomas (HGGs) are devastating central nervous system malignancies. Despite decades of investigation into these lethal childhood brain tumors, aggressive surgical resection combined with conventional chemotherapy and radiation therapy remains the standard of care. Unfortunately, this treatment approach has failed to improve the 5-year survival of patients with cortical HGGs, which continues to be less than 20%. The paucity of curative treatment options for patients with HGGs emphasizes our urgent need to further understand these disease entities at the cellular and molecular level for informed therapeutic approaches. The identification of recurrent histone H3 mutations in pediatric HGGs by my mentor Dr. Suzanne J. Baker and others strongly supports a critical role for epigenetic dysregulation in the etiology of childhood HGGs. Recurrent Gly34Arg/Val substitutions in histone H3.3 (H3.3 G34R/V) occur in more than 15% of cerebral cortex HGGs found in adolescents and young adults. The frequency of these mutations in a subset of cortical HGGs underscores the functional significance of epigenetically dysregulated spatiotemporal gene regulatory programs during development. However, the impact of H3.3 G34R/V on transcriptional regulatory programs contributing to tumorigenesis in a distinct spatiotemporal context within the developing brain remains to be determined. This proposal integrates the expertise of the Baker lab for functional and mechanistic studies in HGG with the pioneering expertise of a group of collaborators who have identified and functionally validated transcriptional core regulatory circuitries (CRC) and other critical tumor dependencies in models of pediatric cancer. By combining cutting-edge genomic platforms and other experimental techniques with clinical training experiences in pediatric neuro-oncology and neurosurgery, I intend to decipher complex transcriptional patterns dysregulated in H3.3 G34R/V HGG to address current limitations in treating this intractable central nervous system malignancy. The Baker lab established a novel collection of age and anatomically matched primary tumors, patient-derived orthotopic xenografts, and a range of cell lines modeling wild-type, mutant, and CRISPR- corrected H3.3 backgrounds for experimental interrogation of transcriptional dysregulation in HGG. Aim 1 leverages chromatin-based assays and RNA interference to identify transcription factors (TF) comprising a transcriptional CRC essential to maintaining an oncogenic cellular state in H3.3 G34R/V HGG. Aim 2 employs CRISPR/Cas9 negative selection screens to comprehensively target TF DNA-binding domains in patient-derived cell lines from H3.3 G34R HGG and expands beyond core TFs comprising a transcriptional CRC to uncover other critical TF gene dependencies in H3.3 G34R HGG. The identification of critical TF gene dependencies in H3.3 G34R/V HGG will enhance our understanding of cancer cell dependency on transcriptional regulatory programs and illuminate potentially actionable biology for the development of novel therapeutic strategies.