Abstract 5447: Microtubule-associated protein MAP2 promotes drug resistance and cancer stemness in hepatocellular carcinoma through integrin dysregulation

Abstract

Abstract Integrins are adhesion molecules that mediate mechanical and chemical signal transduction pathways to support cell survival and proliferation. Dysregulated integrin signaling empowers tumor cells to drive oncogenic stemness functions, including tumor initiation, epithelial plasticity, metastatic reactivation, and resistance to therapies. However, the interplay between cancer stemness and integrin signaling in hepatocellular carcinoma (HCC) remains poorly understood. HCC cells marked by CD133 represent an important functional subset of HCC tumors, displaying a dedifferentiated status with stem cell traits. In this study, transcriptome profiling reveals specific downregulation of integrin α family genes and integrin signaling in ‘HCC’ CD133+ cells isolated from NRAS+AKT-driven HCC, but not epithelial-specific ‘normal’ CD133+ cells isolated from regenerating liver. Of note, one of the most differentially upregulated genes identified in CD133+ HCC cell profiling, microtubule-associated protein MAP2, demonstrates the ability to suppress integrin expression. MAP2 overexpression is frequently observed in HCC and correlates with aggressive clinical and stemness features, including survival, tumor stage, and stemness signatures. Epigenetic modifications by H3K27Ac contribute to MAP2 upregulation. Functionally, MAP2 promotes cancer stemness and cell invasion, and confers resistance to the targeted therapy sorafenib. Mechanistically, the inhibition of collagen-binding integrin α subunits by MAP2 subsequently ablates integrin β1-mediated cell adhesion and FAK signaling. Estramustine Phosphate (EMP), previously reported to inhibit the interaction of MAP2 with actin filaments, attains a synergistic effect in suppressing tumor initiation and growth of HCC cell lines, HCC patient-derived organoids and NRAS+AKT HCC mouse model when used in combination with sorafenib. In summary, MAP2 inhibition may represent a potential novel therapy for HCC by targeting its cancer stemness roots and altering integrin signaling. Ongoing work is focused on the study of MAP2 regulation of integrin signaling and cell behaviours in the maintenance of a more stemness state in HCC. Citation Format: Ut Kei Lou, Ka-Hei Lam, Huajian Yu, Jia Jian Loh, Ki-Fong Man, Lei Zhou, Yuan Gao, Tin-Lok Wong, Cheng-Han Yu, Stephanie Ma. Microtubule-associated protein MAP2 promotes drug resistance and cancer stemness in hepatocellular carcinoma through integrin dysregulation [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 5447.