Abstract 1472: APOBEC-induced non-coding hotspot mutations near LEPROTL1 contribute to the tumorigenicity of bladder cancer via deregulation of LEPROTL1, DCTN6 and SARAF

Abstract

Abstract In bladder cancer, APOBEC3 deaminases are major drivers of genomic mutagenesis, with most of these mutations occurring in synonymous or non-coding regions of the genome. The impact of these mutations on tumorigenesis has not been explored. This study aimed to investigate two non-coding hotspot mutations, likely induced by APOBEC3A near LEPROTL1—chr8: 29,952,919 G>A and chr8: 29,952,921 C>T—in bladder cancer. Using dual-luciferase reporter assays, we found that these mutations enhance both promoter and enhancer activities. Employing multi-omics approaches, including RNA-seq, ChiP-seq, and Hi-C, identified LEPROTL1, DCTN6, and SARAF as target genes co-regulated by a common enhancer where these hotspot non-coding mutations manifest. Isogenic cell lines, generated through CRISPR-mediated base editing to introduce these mutations, exhibited upregulation of target genes, and displayed oncogenic characteristics, such as increased cell growth, proliferation, invasiveness, and resistance to cisplatin. Moreover, these mutations exert their effect on cell proliferation by promoting cell cycle progression. These results suggest that recurrent non-coding somatic mutations upstream of LEPROTL1 disrupt the coregulation pattern of the three genes, thereby promoting bladder tumorigenesis. Citation Format: Bilal Lone, Kelly Butler, Alexandra Dobbins, Dhanusha Yesudhas, Arup Chakraborty, Evan Hickman, Salah Boudjadi, Andrea Apolo, Rouf Banday. APOBEC-induced non-coding hotspot mutations near LEPROTL1 contribute to the tumorigenicity of bladder cancer via deregulation of LEPROTL1, DCTN6 and SARAF [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(6_Suppl):Abstract nr 1472.