Abstract IA18: The post-transcriptional response to bulky-adduct DNA damage

Abstract

Abstract Under conditions of physiological cell stress, including those that are found within a tumor cell and following treatment with chemotoxic drugs that cause DNA damage, post-transcriptional control pathways are initiated to aid cell survival. Global rates of protein synthesis are reduced by altering the phosphorylation status of eukaryotic initiation factors (eIFs), leading to decreases in the levels of ternary complex (required to bring the initiator Met-tRNAi to the 40S ribosomal subunit) and eIF4F complex (which binds to the 7methyl G cap). In parallel with protein synthesis shut down there is reprogramming of the translatome to allow the translation of “survival” mRNAs, which is mediated by RNA motifs within their 5' and 3' untranslated regions (UTRs) and their interaction with RNA binding proteins. Interestingly, the data show that this re-programming of the translatome is dependent upon the type of DNA damage initiated. For example, we have shown that following treatment with agents that cause bulky-adduct DNA damage, such a platinum-based compounds (cisplatin, oxaliplatin) or mitomycin C, the polysomes are enriched with mRNAs that encode enzymes that function in nucleotide excision repair. We have shown that these mRNAs contain regulatory upstream open reading frames (uORFs). Importantly, we have identified a common polymorphism in an uORF in the 5' UTR of the critical DNA repair enzyme ERCC5 and show that this determines sensitivity to platinum-based chemotherapy by controlling ERCC5 translation. Signaling from DNA-PKcs to eIF2 is required as part of this response, and modulation of this pathway alters the synthesis of critical repair enzymes and can chemosensitize cells to treatment with platinum-based compounds. We have used RNA-interactome capture to examine changes in the interactions of RNA binding proteins with their target mRNAs following bulky adduct-DNA damage and have identified a cytoplasmic RNA-BP complex that responds specifically to this type of DNA damage. Citation Format: Anne E. Willis. The post-transcriptional response to bulky-adduct DNA damage. [abstract]. In: Proceedings of the AACR Special Conference on Translational Control of Cancer: A New Frontier in Cancer Biology and Therapy; 2016 Oct 27-30; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2017;77(6 Suppl):Abstract nr IA18.