Abstract 5645: HuR regulates aerobic glycolysis in triple negative breast cancer (TNBC)

Abstract Introduction: The RNA-binding protein Human Antigen R (HuR/ELAVL1) is ubiquitously expressed and exerts post-transcriptional regulation on mRNAs characterized by U/AU-rich sequences in their 3' UTR. Elevated cytoplasmic expression of HuR has been associated with various malignancies, influencing key cellular processes such as proliferation, apoptosis, angiogenesis, and metastasis. The involvement of HuR influences prognostic outcomes and hence is a potential biomarker and therapeutic target in cancer research. The present study investigates the oncogenic role of HuR in TNBCs, an aggressive subtype of breast cancer. Methods: Immunohistochemistry was performed on TNBC patient tumor tissue (n=40) to asses the expressions of HuR and MMP9. Human TNBC cell lines MDA-MB-231 and MDA-MB-468 were used for in vitro studies after confirming cytoplasmic HuR accumulation in these cells via Immunofluorescence. The RNA binding activity of HuR was disrupted using CMLD2, a specific inhibitor of HuR, and subsequent physiological changes were assessed through functional assays. An exploratory investigation of HuR-moderated metabolic changes was performed employing NANOSTRING nCounter XT gene expression assay using metabolic pathways panel. Investigation and/or validation of molecular changes were done via immunoblotting. Results: Meta-analysis using Liu-2014 TNBC dataset correlated high HuR protein expression with reduced patient survival (p=0. 028). HuR (77%) and MMP9 (55%) were found to be overexpressed in TNBC tissues. Inhibiting HuR with CMLD2 resulted in the downregulation of the protein and its downstream targets CDK2, MMP9, and β catenin. HuR inhibition compromised proliferation, migration, Matrigel invasion and EMT (downregulated E-Cadherin, N-Cadherin, and Vimentin) in TNBC cell lines. Further, HuR inhibition resulted in decreased clonogenicity in 2D and 3D TNBC cultures. Transcriptomics studies showed that HuR inhibition in MDA-MB-231 altered the profile of glycolytic genes in addition to other pathways such as cell cycle and DNA damage repair. In accordance, the expression of glycolytic proteins was reduced upon CMLD2 treatment. Similar results were obtained on HuR knockdown by siRNA suggesting that HuR-mediated effects on TNBC progression might be in part through its modulation of aerobic glycolysis. Conclusion: Overall, our results demonstrate HuR as a positive regulator of aerobic glycolysis in TNBCs and the ability of CMLD2 to inhibit HuR provides a rationale to consider it as a potential anticancer agent for TNBCs. Citation Format: Arundhathi Dev J R, Ajay Gogia, Sandeep R. Mathur, S. V. S. Deo, Chandra Prakash Prasad. HuR regulates aerobic glycolysis in triple negative breast cancer (TNBC) 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 (6Suppl): Abstract nr 5645.