Abstract 183: HERG1 potassium channels perturb the β1 integrins mediated force transduction machinery in pancreatic cancer
Authors: Coppola Stefano , Duranti Claudia , Arcangeli Annarosa , Schmidt Thomas 
Published: August 2018

Abstract
Ion channels regulate cell proliferation, differentiation, and migration in normal and neoplastic cells through cell-cell and cell-extracellular matrix (ECM) transmembrane receptors called integrins. K+ flux through the human ether-à-gogo-related gene 1 (hERG1) channel shapes action potential firing in excitable cells such as cardiomyocytes. Its abundance is often aberrantly high in human tumors, including the pancreatic ductal adenocarcinoma (PDAC). We recently demonstrated that the direct interaction of β1 integrins with hERG1 channels in cancer cells stimulated distinct signaling pathways that depended on the conformational state of hERG1 and affected different aspects of tumor progression [1].
We hypothesized that hERG1 channels compromise the PDAC mechano-reciprocity, the ability to dynamically respond to externally applied forces by exerting forces, which enhances invasion and compromises treatment.
Using elastic micropillar arrays of varying stiffness (20-150 kPa) [2], we quantified the β1-integrin mediated forces exerted by PANC-1 cells. Micropillars coating with collagen and/or fibronectin derived peptides allowed us to direct cell surface receptor binding specificity (i.e. α2β1 and α5β1 integrins). Independently of the substrate coating, PANC-1 cells exerted higher forces as a function of substrate stiffness, as already demonstrated for other cell types. Remarkably, the disruption of the β1/hERG1 interaction through E4031 inhibition of hERG1 channels resulted in a significant increase in the detected cellular forces by ~20%, accompanied by an increase of focal adhesion areas as demonstrated by staining with vinculin.
Our results suggest that, in addition to alter distinct signaling pathways and tumor progression [1], the direct interaction of β1 integrins and hERG1 channels perturbs the force transduction machinery. These findings encouraged us to develop bispecific antibodies (scDb, single-chain diabody) binding to the β1/hERG1 complex that are now being validated in PDAC cell lines. In particular, we have developed a bispecific antibody (scDb-β1/hERG1) [3], which is composed by the variable domains (VH and VL chains) of monoclonal antibodies binding two different antigens, hERG1 and β1 integrin. Data obtained from in vitro studies demonstrates that the scDb antibody impacts cell viability and migratory behavior in Mia PaCa-2 cell lines, holding promises for translational impact after a further validation in vivo as a novel candidate in cancer therapeutics.
[1] Becchetti et al. Science Signaling (2017), 10 (473), eaaf3236.
[2] van Hoorn et al. Nano Lett (2014), 14, 4257-4262.
[3] Patent: “Novel antibodies”. Inventors: Annarosa Arcangeli, Claudia Duranti, Silvia Crescioli, Laura Carraresi. Patent Deposit: July 2017. Patent Ref: 102017000083637 (University of Florence).
Citation Format: Stefano Coppola, Claudia Duranti, Annarosa Arcangeli, Thomas Schmidt. HERG1 potassium channels perturb the β1 integrins mediated force transduction machinery in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 183.