Abstract C036: Investigating the phenotypic changes in in vitro and in vivo cancer models expressing isocitrate dehydrogenase 1 (IDH1) mutations R132H and R132Q
Authors: Adam Mowaffaq A.A. , Robinson Mikella , Hoang An , Wells Grace A. , Scott David A. , Zagnitko Olga , House Carrie , Sohl Christal D. 
Published: December 2023

According to the National Cancer Institute, there were 25,050 new brain cancer cases in 2022, representing 1.3% of all cancer incidents in the United States. In the same year, the estimated death was 18,280 cases, representing 3.0% of all cancer deaths. Relative survival statistics between 2017 and 2018 showed that only 32.5% of patients would survive five years or more. Disparities in cancer incidence and outcomes, including brain cancers, can be due to biological, socioeconomic, and care access factors that often have roots in structural racism. Research shows lower three years survival rates of glioblastoma in the African American population by 28.8% compared to the Asian Pacific Islanders at 36.6% and Hispanic at 32.3%. Mutant isocitrate dehydrogenase 1 (IDH1) can lead to brain cancer, including &gt; 80% of lower-grade gliomas and secondary glioblastomas. Mutant IDH1 catalyzes the NADPH-dependent conversion of α-ketoglutarate to D2-hydroxyglutarate (D2HG), an oncometabolite linked to many cancer types. IDH1 mutation occurs primarily at residue 132, and our lab has shown that the catalytic activity differs based on the amino acid substituted at that location. There is a lack of information describing the relation of D2HG produced to cancer cells’ phenotype severity. Understanding IDH1 mutation will clarify cancer progression, patients’ prognosis, and treatment responses. Here, we hypothesize that the toxic effect of D2HG will impair the viability of cells expressing mutant IDH1 and will cause a reduction in ROS and NADPH cellular levels. This work examines D2HG production efficiency in vivo and in vitro and the metabolic consequences of this oncometabolite. We created cell lines stably overexpressing IDH1-R132Q and IDH1-R132H to conduct this work. Our results showed higher levels of D2HG in cells expressing IDH1-R132Q compared to DH1-wild type and IDH1-R132H, supportive of our previous finding that IDH1-R132Q mutation has higher catalytic activities (higher efficiency in producing mutant IDH1). These higher D2HG levels caused cells to proliferate and migrate at lower rates. D2HG interferes with DNA demethylation by inhibiting the TET enzyme, and we observed higher levels of histone protein expression in IDH1-R132Q compared to the other modified cells. In in vivo studies, we identified elevated D2HG levels in mouse xenografts expressing IDH1-R132Q that affected tumor growth.

Citation Format: Mowaffaq A.A. Adam, Mikella Robinson, An Hoang, Grace A. Wells, David A. Scott, Olga Zagnitko, Carrie House, Christal D. Sohl. Investigating the phenotypic changes in in vitro and in vivo cancer models expressing isocitrate dehydrogenase 1 (IDH1) mutations R132H and R132Q [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr C036.