Ruan, Kai

Abstract Gliomas are highly malignant brain tumors with poor prognosis and short survival. Nicotinamide adenine dinucleotide (NAD+) plays a critical role in cancer progression, yet anti-cancer therapies targeting NAD+ synthesis have had limited clinical success due to an incomplete understanding of its mechanisms. Here, we demonstrate the essential role of the NAD+ synthase nicotinamide mononucleotide adenylyltransferase (NMNAT) in glioma progression and its novel contribution to nuclear atypia. Analysis of the patient glioma transcriptomics dataset (GAPIA) indicated a strong correlation between high NMNAT transcription levels and poorer disease-free survival in low grade glioma (LGG) and glioblastoma multiforme (GBM). Utilizing quantitative statistical analysis to assess the size and circularity of about 3 million cells in glioma tissue samples from 19 patients, we identified the significant association between NMNAT1 protein level and increased nuclear atypia in different types of gliomas. Mechanistic studies in human glioma cells and a Drosophila glial neoplasia model revealed that NMNAT enhances glioma growth by promoting NAD+-dependent post-translational modifications poly(ADP-ribosyl)ation (PARylation) and deacetylation of p53, thereby attenuating the pro-apoptotic activity of p53. Additionally, NMNAT1 disrupts nuclear lamina integrity by altering lamin A/C distribution, further contributing to nuclear atypia and glioma progression. These findings uncover a novel tumorigenic mechanism involving NMNAT's regulation of nuclear architecture and NAD+-mediated metabolic signaling pathways, highlighting its roles in glioma growth and nuclear atypia. This study underscores NMNAT as a potential therapeutic target in glioma treatment. Citation Format: Jiaqi Liu, Xianzun Tao, Yi Zhu, Xiang Gao, Tijana Canic, Kai Ruan, Zoraida Diaz-Perez, Sakir Humayun Gultekin, Priyamvada Rai, Qunfeng Dong, Grace Zhai. NMNAT-mediated NAD+ metabolism promotes glioma growth by modulating p53 post-translational modifications and nuclear atypia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB060.

Disrupted nucleocytoplasmic transport (NCT) has been implicated in neurodegenerative disease pathogenesis; however, the mechanisms by which disrupted NCT causes neurodegeneration remain unclear. In a Drosophila screen, we identified ref(2)P/p62 , a key regulator of autophagy, as a potent suppressor of neurodegeneration caused by the GGGGCC hexanucleotide repeat expansion (G4C2 HRE) in C9orf72 that causes amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). We found that p62 is increased and forms ubiquitinated aggregates due to decreased autophagic cargo degradation. Immunofluorescence and electron microscopy of Drosophila tissues demonstrate an accumulation of lysosome-like organelles that precedes neurodegeneration. These phenotypes are partially caused by cytoplasmic mislocalization of Mitf/TFEB, a key transcriptional regulator of autophagolysosomal function. Additionally, TFEB is mislocalized and downregulated in human cells expressing GGGGCC repeats and in C9-ALS patient motor cortex. Our data suggest that the C9orf72 -HRE impairs Mitf/TFEB nuclear import, thereby disrupting autophagy and exacerbating proteostasis defects in C9-ALS/FTD.