Acidic pHe regulates cytoskeletal dynamics through conformational integrin β1 activation and promotes membrane protrusion

An acidic extracellular pH (pHe) in the tumor microenvironment has been suggested to facilitate tumor growth and metastasis. However, the molecular mechanisms by which tumor cells sense acidic signal to induce a transition to an aggressive phenotype remain elusive. Here, we showed that an acidic pHe (pH 6.5) stimulation resulted in protrusion and epithelial-mesenchymal transition (EMT) of cancer cells, which promoted migration and matrix degeneration. Using computational molecular dynamics simulations, we reported acidic pHe-induced opening of the Integrin dimers (α5β1) headpiece which indicated the activation of integrin. Moreover, acidic pHe promoted maturation of focal adhesions, temporal activation of Rho GTPases and microfilament reorganization through integrin β1-activated FAK signaling. Furthermore, mechanical balance of cytoskeleton (actin, tubulin and vimentin) contributed to acidic pHe-triggered protrusion and morphology change. Taken together, these findings revealed that integrin β1 could be a novel pH-regulated sensitive molecule which confers protrusion and malignant phenotype of cancer cells. [Display omitted] •Acidic pHe stimulates protrusion and EMT of cancer cells.•Acidic pHe conformationally activates integrin β1 and FAK/Src signaling.•Acidic pHe temporally actives Rho GTPases and microfilament reorganization.•Acidic pHe-induced mechanical balance of cytoskeleton network contributes to protrusion.