LAUSR

Introduction: Cell invasion is a critical step for tumor progression and dissemination into neighboring and distant tissues, which constitute the foremost cause of cancer mortality. Loss of the cell-cell adhesion molecule E-cadherin occurs in 70% of carcinomas and is widely described as an initiating event in the invasion process. Recently, data has emerged demonstrating that this milestone phenomenon is accompanied by an abnormal affair between cancer cells and the extracellular matrix (ECM). In fact, cancer cells display increased plasticity and a remarkable ability to overcome the fibrous structure of the ECM. Since the nucleus is the largest and stiffest organelle in the cell, we hypothesize that it represents a major determinant of cell reshaping and spreading capacity. Our main aim is thus to dissect the mechanisms through which the nucleus supports invasion of cancer cells. Material and Methods: To determine alterations in nuclear composition and architecture that are distinctive of cells with E-cadherin impairment, we have used cell lines and Drosophila strains expressing either wild-type E-cadherin or the Y755C variant identified in Hereditary Diffuse Gastric Cancer (HDGC) patients. Nuclear morphological features and migratory rates were assessed by fluorescent markers coupled with confocal microscopy and advanced bioimaging techniques. The molecular profile of nuclei envelope from E-cadherin mutant and wild-type cells was subsequently investigated by implementation of a proteomic workflow, encompassing cellular fractionation and processing through high-resolution Mass Spectrometry (LC-MS). Results: We have shown that the Y755C E-cadherin mutation induces evident changes in nuclear morphology, and an increased migration performance of border cells in Drosophila. In particular, detailed quantitative measurements revealed differences in nuclear area, mean intensity, perimeter, solidity and relative position to basal surface of E-cadherin mutant cells, when compared with those expressing the wild-type protein. Further, proteomic analysis of enriched nuclear fractions disclosed that the composition of the nuclear envelope from E-cadherin mutant cells is significantly different from that of the wild-type counterparts. Differentially abundant molecules include proteins relevant for spatial and structural integrity of the nucleus. Conclusion: Overall, this work provides evidence that cells with E-cadherin loss of function activate a specific mechanotransduction program that imposes nuclear remodeling at physical and biochemical levels, endowing cells with a pro-invasive signature. Citation Format: Joana Figueiredo, Joana Pereira, Rui M. Ferreira, Luísa Carvalho, Margarida Gonçalves, Soraia Melo, Patrícia Carneiro, Parry Guilford, Eurico Morais-de-Sá, Raquel Seruca. Nucleus positioning and composition dictate the invasion performance of E-cadherin mutant cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5815.