Differential AXL expression and Arf1 regulation control stiffness-dependent Golgi organization in breast cancer cells

Abstract

Integrin-mediated adhesion regulates cellular survival and mechanotransduction, processes often deregulated in cancers. During breast tumor progression, matrix stiffening influences cytoskeletal organization, although its effect on organelle organization and function remains unclear. Here, we examine how Golgi organization responds to matrix stiffness sensing in breast cancer cells. In adherent MDA-MB-231 cells, the Golgi becomes progressively more compact and organized with increasing matrix stiffness, accompanied by enhanced tubulin acetylation, indicating stiffness-dependent regulation. In contrast, MCF7 cells display a diffused or disorganized Golgi regardless of matrix stiffness. AXL, a receptor tyrosine kinase differentially expressed in MDA-MB-231 cells and absent in MCF7, localizes prominently to the Golgi. Inhibition or knockdown of AXL disrupted stiffness-dependent Golgi organization in MDA-MB-231 cells, whereas stable AXL expression in MCF7 restored Golgi organization at higher stiffness. A stiffness-dependent increase in AXL and Arf1 expression regulates Arf1 activation and localization to control mechanosensitive Golgi organization. Inhibition of AXL and/or Arf1 disrupted Golgi organization, tubulin acetylation and cell-surface glycosylation. Together, our findings reveal a mechanoresponsive AXL-Arf1-Golgi signaling axis that integrates matrix stiffness sensing with Golgi organization and function in breast cancer cells.