Abstract 1891: Annexin A2-binding S100 proteins promote proliferation and cell cycle progression of EGFR positive cancer cells

(a) Aim: The purpose of this study is to clarify an unknown function of Annexin A2-binding S100A proteins in tumor growth, cell cycle progression and invasion. Annexin A2 is a membrane bound protein originally identified as v-Src substrate, and often found to be overexpressed in many types of cancers. As a multicompartmental protein that orchestrates a spectrum of dynamic membrane-related events, it is associated with actin cytoskeleton control, vesicle formation and intercellular interaction. (b) Methods and Results: During our proteomics analysis using solid tumor cell lines, we identified both Annexin A2 and S100A proteins in cancer stem cell-rich population. We next examined S100A proteins expression in several Head and Neck cancer PDX samples. Immunohistochemical data from in vivo specimens as well as western blots showed that S100A expression abundance was well associated with poor prognosis. Annexin A2 has been indicated to be involved in malignant phenotypes such as invasion and metastasis, and Annexin A2 and S100A form (S100-Annexin A2)x2 dimers, we next examined roles of S100A proteins in cancer, by using shRNA-mediated depletion experiments. (c) New Findings: Depletion of S100A from PDX-derived cancer cells resulted in loss of both in vivo tumor formation and invasion. Furthermore, cell cycle progression was inhibited by the depletion, suggesting its potential role in proliferation controls. Similar to the mutant Ras-driven tumors, EGFR-overexpression increased S100A gene expresssion. (d) Conclusion: These results strongly suggest that increases in S100A plays significant roles in cancer cell proliferation and invasion. Note: This abstract was not presented at the meeting. Citation Format: Naoko Ogama, Ryuuichi Nagashima, Nobuyuki Tanaka. Annexin A2-binding S100 proteins promote proliferation and cell cycle progression of EGFR positive cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1891. doi:10.1158/1538-7445.AM2017-1891