Abstract 3062: Unraveling the role of RCC2 in glioblastoma by mutational analysis and a murine model of glioma

Abstract Glioblastoma (GBM) is a brain malignancy characterized by being highly aggressive, lethal, yet treatment modalities remain limited. Recent studies have implicated Regulator of Chromosome Condensation 2 (RCC2), a guanine nucleotide exchange factor (GEF) for RalA, as a potential regulator in glioblastoma pathogenesis. RCC2 has been shown to play a role in promoting glucose metabolism through BACH1-dependent upregulation of hexokinase II (HK2) (1). In this study, we investigated the functional mechanism of RCC2 in gliomagenesis using two complementary approaches. First, the relevance of RCC2 structural regions on its downstream functions were examined. By superimposing the three-dimensional crystal structure of RCC2 onto RCC1 (Regulator of Chromosome Condensation 1), a related GEF, we identified several unique regions within the RCC1-like domain of RCC2. A panel of point, substitution, and deletion mutants were generated, and pulldown experiments were performed to assess their relative binding affinity with BACH1. Additional assays to assess their relative ability to modulate the expression of HK2 and other cellular parameters will be discussed. The structure-functional characterization of distinct regions within RCC2 may identify unique sequences within RCC2 that could have relevance to glucose metabolism, cell proliferation and cell motility. Additionally, we have established a murine glioma model utilizing a Pten heterozygous mice expressing a GFAP-Cre-recombinase transgene (Gfap-cre;Ptenfl/+). Glioma were induced by stereotaxically injected lentiviral constructs expressing either with HRasV12 oncogene alone or together with RCC2. Neurological symptoms were monitored over a period of 7 months, and histopathological analysis was performed to evaluate the morphological and molecular features of the tumors. We showed that co-expression of HRasV12 and RCC2 exhibited earlier emergence of neurological manifests in both male and female groups (Log-rank test, p0. 05) when compared to HRasV12 alone. Overall, our study provides insights into both the structural mechanism of RCC2 in gliomagenesis through mutational analysis of RCC2 and the functional relevance through a murine model of glioma. (1) Liu, T. et. al. Cancer Lett (2022) 549: 215914. Funding: This work is supported by a General Research Fund grant (#14113519) from the University Grants Committee of Hong Kong. Citation Format: Wayne L. H. Ho, Penelope M. Y. Or, Andrew M. Chan. Unraveling the role of RCC2 in glioblastoma by mutational analysis and a murine model of glioma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3062.