Abstract
Abstract Annexins are calcium-dependent phospholipid binding proteins that act on several cellular functions such as cytoskeleton organization, ion transport, and cell signalling. Due to its relation to the actin structure and cell proliferation; alterations in its expression have known implications in the progression of distinct cancer types. Among the proteins of the family, annexin A2 (AnxA2) is known for promoting cell proliferation, migration, and invasion when overexpressed. A recent study suggested AnxA2 as a diagnostic and prognostic biomarker for colorectal cancer. However, there is little evidence of its regulation and role in cell signalling pathways involved in colorectal cancer tumorigenesis. Our goal is to unravel the role of AnxA2 in the tumor progression and the signalling pathways involved. The total and phosphorylated (Y23 residue) AnxA2 levels were assessed in three human colorectal cancer cell lines (Caco-2, HT-29 e HCT-116), through imunoblotting. HT-29 cells, control or silenced (siRNA) for AnxA2, were submitted to TGF-β; treatment to induce characteristic epithelyal-mesenchymal transition (EMT) events. Proliferation, migration, and invasion were also assessed for these cells. Our results show that Caco-2 cells have the lowest phosphorylation level among the analyzed cells. In face TGF-β; treatment, the HT-29 cell line showed morphologic alterations characteristic to EMT, reduced E-cadherin protein levels, and increased vimentin expression. AnxA2 (total and phospho) expression was also enhanced. The loss of cell-cell contacts due to treatment was observed with the internalization of E-cadherin and AnxA2. The analysis of such internalization through Structured Illumination Microscopy (SIM) allowed us to observe intracellular colocalization between these two proteins. Proliferation assays reveal that TGF-β; has antiproliferative effects and in a less drastic form so does AnxA2 siRNA. AnxA2 silencing also reduced cell migration in Wound Healing assay, in a manner independent of TGF-β. The EMT induction through treatment also led to incresead invasion, which was inhibted with AnxA2 silencing or STA21 pretreatment (STAT3 selective inhibtor). Results suggest that AnxA2 has a role in cellular junction disassembly and enhanced invasion ability, characteristics of EMT process, and in cellular proliferation and migration. Citation Format: Murilo Ramos Rocha, Annie Cristhine Moraes Sousa Squiavinato, Pedro Barcellos de Souza, Jose Andres Morgado Diaz. Annexin A2 as a regulator of colorectal tumorigenesis: Influence over epithelial-mesenchymal transition and invasive abilities [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr A84.
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