Integrin-mechanosignaling role in small GTPases activation and cancer.

COLO G.P.; CURINO A. C.; FACCHINETTI M.M.; FASSLER R

Bs. As.

Congreso; Reunión Conjunta de Sociedades de Biociencias. LXII Reunión Anual de la Sociedad Argentina de Investigaciones Clínicas (SAIC),; 2017

Sociedad Argentina de Investigaciones Clínicas (SAIC)

Abstract The ability of cells to adhere and simultaneously probe their mechanical environment is central to many developmental, homeostatic but also pathological processes. Yet, the molecular mechanisms that govern mechanotransduction during cell adhesion and invasion are complex and remain incompletely understood. We determined the importance of studying integrins in genetically modified cell models that only express either family of fibronectin (FN)-binding integrins. Using biochemical assays in combination with mass spectroscopy, traction force microscopy and micropatterns, we observed that α5β1-integrins (pKO-β1) promote the formation of small nascent adhesions with high turnover, low RhoA activation and high force, while αVβ3 (pKO-αV) promotes adhesion maturation leading to large focal adhesions connected to contractile stress fibers resulting in high RhoA and low force, while cells expressing both integrins contain small and large adhesion structures and intermediated GTPases activites. Therefore, we observed that the levels of integrins expression and subtype in different cells lines affect G-actin polymerization, MRTF-A/SRF activation and the ubiquitin-like modifier interferon-stimulated gene 15 (ISG15) expression that promotes cell migration and invasion. Interestingly, the malignant breast cancer cell line MDA-MB-231 expressing high levels of β1 integrins and the β1-class expressing pKO-β1 cells showed high ISG15 expression and high amounts of ISGylated proteins, which we could show are directly responsible for cell invasion. In contrast, the non-invasive tumor cell lines MDA-MB-468 or MCF-7 and the αV-class integrin expressing pKO-αV cells, which display low levels of β1 integrins, ISG15 and ISGylated proteins failed to invade a 3D matrix. The future findings have important implications for our understanding of cancer progression and will help identifying new targets for future therapies.