Defining the cell intrinsic and tumor immune microenvironment mechanisms of DNA-PKcs in radiotherapy resistance in glioblastoma

The goal of this K08 Career Development Award is to train Dr. S. John Liu, a second year Assistant Professor in Residence at UCSF, in the skills he will need to become an independently funded physician-scientist capable of basic and translational investigation in neuro-oncology. Dr. Liu proposes to investigate the role of DNA-PKcs, a kinase well described in DNA repair but relatively underappreciated in non-canonical functions such as tumorigenesis and tumor-immune signaling. The proposal is an extension of his previous work on developing and implementing single cell functional genomics tools to identify and validate genetic regulators of radiotherapy resistance, which is a major problem in the treatment of patients with glioblastoma (GBM). Dr. Liu has shown through unbiased genome-wide CRISPR screens, in vivo perturb-seq experiments, intracranial xenografts, and spatial transcriptomics of patient tumors that inhibition of DNA-PKcs combined with radiotherapy results in decreased pro-growth gene expression and remodeling of the tumor immune microenvironment in GBM. In Aim 1, Dr. Liu will investigate the tumor cell-intrinsic mechanisms of how DNA-PKcs drives resistance to radiotherapy and cell survival in GBM, focusing on transcriptional regulation through chromatin binding and interactions between DNA repair and interferon signaling. In Aim 2, Dr. Liu will investigate how DNA-PKcs regulates the tumor immune microenvironment in syngeneic animal models of GBM. He will then determine the role of the cGAS/STING pathway in the anti-tumor effects of DNA-PKcs inhibition, followed by therapeutically targeting this pathway through STING agonism. In Aim 3, Dr. Liu will validate tumor immune microenvironment reprogramming using patient tumor biospecimens from a clinical trial of DNA-PKcs inhibition and radiotherapy for GBM. This proposal uses vertebrate animals because understanding glioblastoma, a complex disease that involves tumor, stromal, and immune cells, requires experimentation in mice in which the tumor immune microenvironment cannot yet be entirely recapitulated in vitro. Dr. Liu’s career development and research plans include a combination of formal coursework tailored to fill his specific knowledge gaps, national workshops, international conferences, and intensive hands-on research experience that will take place at UCSF, a leading NCCN Comprehensive Cancer Center with an excellent track record in basic and translational neuro-oncology research. Dr. Liu’s training plan specifically focuses on areas that are underdeveloped in his research skillset, specifically (1) molecular biology and radiobiology research methods, (2) tumor immunology knowledge and research methods, (3) translational research skills in neuro-oncology, and (4) leadership and laboratory management skills to achieve and sustain independence. This project will be mentored by David Raleigh, Associate Professor of Radiation Oncology, Neurological Surgery, and Pathology at UCSF who is an experienced mentor well suited to train Dr. Liu in these key areas. Dr. Liu has a highly distinguished but available advisor committee possessing synergistic expertise spanning basic, translational, and biostatistical sciences to guide his research and career trajectory. Successful completion of this proposal will train Dr. Liu for independence and also provide mechanistic understanding of RT resistance in GBM, while elucidating rationally informed combination therapy strategies that may improve outcomes for patients with GBM. Project Number: 1K08CA304353-01A1 | Fiscal Year: 2026 | NIH Institute/Center: National Cancer Institute (NCI) | Principal Investigator: Siyuan Liu | Institution: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO, SAN FRANCISCO, CA | Award Amount: $286,881 | Activity Code: K08 | Study Section: Special Emphasis Panel[ZRG1 CTH-K (83)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11371554