Abstract 6673: Alternate mechanism of translation initiation in TNBC metabolism

Abstract Triple-negative breast cancer (TNBC) is a highly aggressive and metastatic subtype of breast cancer. Metastasis is considered one of the primary causes of mortality in cancer patients. TNBC has been shown to exhibit advanced cancer hallmarks, such as metabolic reprogramming and selective mRNA translation, which contribute to metastatic progression. Previous studies show that TNBC utilizes an alternate cap-dependent translation mechanism mediated by Death Associated Protein 5 (DAP5). Our studies indicate this alternate translation plays an essential role in metabolic reprogramming. Analysis from genome-wide translatome studies, qRT-PCR, Western blot analyses, as well as metabolomic assays on the TNBC cell line (MDA-MB-231) with non-silencing controls (shNsi) and DAP5-silenced (shDAP5) samples indicate that this alternate translation plays a significant role in the metabolic reprogramming. DAP5 silencing reduces the translation of several glucose metabolism-related mRNAs, independent of their steady-state abundance, and reduces proteins associated with glycolytic metabolism. Targeted metabolomics shows that DAP5 silencing alters metabolites critical in breast cancer energy metabolism. Our findings also suggest that DAP5-dependent translation may selectively regulate metabolic mRNAs under stress conditions when canonical mTORC1/eIF4E cap-dependent translation is attenuated. This alternative translation initiation mechanism suggests this metabolic switch is necessary for malignant progression and metastasis in TNBC cells. These results provide new insights into the molecular mechanisms underlying metabolic reprogramming in metastatic breast cancer and may offer novel therapeutic targets for TNBC treatment. Citation Format: Emilia F. Carlo, Erna Mitaishvili, Columba de la Parra. Alternate mechanism of translation initiation in TNBC metabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6673.