Abstract 2771: Increased mtDNA copy number via EPOR signaling: A potential mechanism for metastatic dissemination in head and neck squamous cell carcinoma
Authors: Chauhan Anshika , Boora Geeta S. , Ghosh Sahana , Patra Subrata K. , Verma Roshan K. , Bakshi Jaimanti , Chatterjee Debajyoti , Srinivasan Radhika , Ghoshal Sushmita , Maitra Arindam , Pal Arnab 
Published: March 2024

Abstract
Introduction: Head and Neck Squamous cell carcinoma (HNSCC) is characterized by high degree of invasion, locoregional metastasis, relapse which leads to overall poor prognosis. The molecular mechanism responsible for aggressiveness is poorly understood. A better understanding of molecular pathways involved shall precede the identification of newer diagnostic tools and therapeutic targets. We explored EPOR signaling pathway in Circulating tumor cells (CTCs) and HNSCC cell lines.
Methods and Results: By using a validated in-house CTC isolation protocol, which addresses various drawbacks of currently available techniques and isolates CTCs suitable for various downstream molecular analysis, we isolated CTCs from HNSCC patients. The whole transcriptome analysis was performed from CTCs using ultra-low cell number RNA sequencing and corresponding primary tumors in 24 paired samples. We found a significant transcriptomic heterogeneity in CTCs, which are associated with overall disease outcome in HNSCC patients. To explore the plausible molecular pathways, we also identified 521 differentially expressed genes in CTCs with respect to primary tumors and various canonical pathways including oxidative phosphorylation, TCA cycle, cytokine-cytokine receptor interaction signaling, and ECM receptor interaction were enriched in CTC samples. Overexpression of erythropoietin receptor (EPOR) along with various genes encoded by mitochondrial genome and genes involved in maintenance of mtDNA in CTCs as compared to primary tumors was an important finding from our data. When analyzed in depth, there was a significant positive correlation between various genes involved in mtDNA maintenance (ABAT, NT5M) and encoded by mitochondrial genome (MT-ND1, MT-ND2, MT-ND4, MT-ND5, MT-ND6, MT-CO1, MT-CO2, MT-ATP6, MT-CYTB) with EPOR expression in our RNA seq data which is also substantiated by analyzing TCGA data. We confirmed these findings experimentally in HNSCC cell lines Cal 27 and FaDu. It was also observed that metastatic cell line FaDu has significantly higher mtDNA content as compared to non-metastatic cell line Cal 27, which was correlated with EPOR expression. Treatment with low dose Erythropoietin (0.1IU/mL) which a natural ligand for EPOR, enhanced mtDNA content in both the cell lines at low doses and boosted the metastatic capability while minimal effect on cell proliferation was observed.
Conclusion: EPOR signaling might promote the metastatic ability of cancer cells and may act as a potential target for cancer dissemination and metastasis.
Citation Format: Anshika Chauhan, Geeta S. Boora, Sahana Ghosh, Subrata K. Patra, Roshan K. Verma, Jaimanti Bakshi, Debajyoti Chatterjee, Radhika Srinivasan, Sushmita Ghoshal, Arindam Maitra, Arnab Pal. Increased mtDNA copy number via EPOR signaling: A potential mechanism for metastatic dissemination in head and neck squamous cell carcinoma [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 2771.