Exploring the relationship between miR-9-5p levels and MAP1B expression in laryngeal cancer cell lines

Abstract Background: Low miR-9-5p expression has been associated with poor overall survival in head and neck squamous cell carcinoma (HNSCC), whereas higher expression is associated with better outcomes. Our previous studies determined that low miR-9 levels is a significant feature of advanced stage laryngeal squamous cell carcinoma (LSCC) specifically in Black patients. We further showed that low miR-9 is associated with increased cell proliferation and decreased chemosensitivity to cisplatin. In this study, we sought to explore the relationship between low miR-9-5p- and high miR-9-5p-LSCC cell lines and its genomic and potential chemotherapeutic target, microtubule-associated protein 1B (MAP1B). Methods: We used four cell lines derived from patients with advanced stage LSCC: UM-SCC-98, UM-SCC-12, UM-SCC-11A, UM-SCC-10A (University of Michigan). Mature miR-9-5p levels were determined in each cell line via northern blotting. Baseline chemosensitivity (IC50 of cisplatin) as well as cell proliferation of each cell line was assessed using the Cell Titer Blue Viability assay. Baseline MAP1B gene and protein expression were determined in each cell line via qPCR and western blotting, respectively. Results: The lowest mature miR-9-5p levels were found in UM-SCC-98 followed by UM-SCC-12. The highest mature miR-9-5p levels were found in UM-SCC-11A followed by UM-SCC-10A. Cell lines with lower miR-9-5p resulted in increased cell proliferation and higher cisplatin IC50 (p < 0.0001): UM-SCC-98 IC50 = 18.32µM and UM-SCC-12 IC50 = 16.70µM. Conversely, cell lines with higher miR-9-5p levels resulted in lower cell proliferation and lower cisplatin IC50; UM-SCC-11A IC50 = 2.28µM and UM-SCC-10A IC50 = 10.95µM. An inverse relationship between miR-9-5p levels and MAP1B gene expression was seen, wherein the low miR-9-5p expressing cell lines (UM-SCC-98 and UM-SCC-12) had the highest gene expression levels; the high miR-9-5p expressing cell lines (UM-SCC-11A and UM-SCC-10A) had the lowest gene expression levels (p < 0.0001, fold change >2). Lower miR-9-5p levels also corresponded with higher MAP1B protein expression, wherein expression was only seen in cell lines UM-SCC-98 and UM-SCC-12. No MAP1B protein expression was seen in UM-SCC-11A and UM-SCC-10A (p < 0.0001). Conclusion: This study further supports the relevance of low miR-9-5p in the regulation of cisplatin chemosensitivity in LSCC. MAP1B, a described mediator of chemoresistance, may be a future target for intervention. Future studies will involve exploring mechanisms of miR-9-5p inhibition and defining MAP1B regulatory pathways. Citation Format: Christina Gobin, Chayil C. Lattimore, Jai Walker, Kristianna M. Fredenburg. Exploring the relationship between miR-9-5p levels and MAP1B expression in laryngeal cancer cell lines [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr C068.