Cellular and Molecular Mechanisms of Mechanotransduction Involved in Metastasis - an in Vitro Study in Hepatocarcinoma and Breast Cancer Cell Lines

Abstract

ABSTRACT Introduction: Invasiveness of tumors requires several distinct cellular functions including lost of cellular adhesion, cell detachment, altered motility and extracellular matrix interaction. This interaction between cells and its surrounding tissues involves mechanical stimuli that are transmitted into cells and translated into a biochemical response - mechanotransduction. The increased mechanical forces made by a stiff microenvironment would contribute to the aggressiveness of solid tumors. Objectives: To study the effects of increased pressure on hepatocarcinoma and breast cancer cells prolifera-tion, migration, adhesion, cytoskeleton organization and invasiveness. Methods: A breast cancer (MCF7) and hepatocellular carcinoma (HUH7) cell line were submitted to a constant increase of atmospheric pressure, 40 mmHg and 60 mmHg, in an airtight box during 4 hours. We analyzed: 1, Cell viability followed by propidium iodide cell cycle evaluation assay; 2, Cell migration by the scratch assay; 3, the expression of integrins by western blot using specific antibodies; 4, the actin cytoskeleton by fluorescent microscopy; and 5, Invasiveness using an invasion kit with a polycarbonate basement membrane. Results: Increasing pressure caused an increased in the viability at 4h after the mechanical stimulation, and that was sustained for 24h. Those results were complemented with cell cycle analysis showing an increment in the cells in S-phase confirming the proliferative effect. We observed a pressure-dependent single-cell detachment pattern on both cell lines when compared to controls. This migratory pattern was studied the cell-cell and cell-substrate adhesions molecules (E-cadherin and b-catenin, and b1integrin, respectively) which revealed decreased. It seems an amoeboid migration variant of the single-cell migration pat-tern.Besides that, cells submitted to pressure presented an increase in stress fibers, a cortical actin pattern, lamelipodia and filopodia. Conclusions: In this work, we demonstrated that the mechanical stimuli have a critical role in migration and invasion in the breast cancer and hepatocellular carcinoma cells. Our results open new perspectives on the role of mechanotransduction in cancer metastasis. The exploration of the signaling pathways involved could represent future possible therapeutic targets. Disclosure: All authors have declared no conflicts of interest.