Optimal mechanical stretch promotes TSP-1 expression through Akt and GSK-3β/β-catenin signaling pathways in keloid formation.

Abstract

Abstract Background: The formation of keloids is influenced by various factors, with local mechanical stretch being recognized as a significant contributing component. Thrombospondin-1 (TSP-1) is identified as a tension-sensitive protein. However, the relationship between TSP-1 and keloid formation induced by mechanical stretch remains unknown. Materials and Methods: A simple customized mechanical stretch device was used for the application of homogeneous equibiaxial stretch (HES). Using Western blot and RT-PCR, the optimal stretch strength and duration were determined. Regarding the functional changes induced by stretch in keloid fibroblasts (Kfbs), cell function assays were used. The relationship between TSP-1 expression and stretch-induced scar formation in human and animal models was investigated using immunohistochemistry. The knock-down of TSP-1 in fibroblasts served as a reverse test. The potential signaling pathway, namely Akt and GSK-3β/β-catenin, were evaluated using western blot. Results: Optimal HES (oHES) could be achieved with four rotations of the screws on our mechanical stretch device, resulting in a significant increase in vimentin, Col I, and fibronectin expression in Kfbs on day 5. Additionally, oHES significantly promoted cell proliferation and migration, but not apoptosis. oHES resulted in the upregulation of TSP-1 expression in both in vitro and in vivo experimental settings. By knocking down TSP-1, the expression of proteins, particularly Col I, and the oHES-induced alterations in the cellular function of Kfbs could be significantly reduced. The inhibition of TSP-1 may attenuate pHES-induced keloid formation through the Akt and GSK-3β/β-catenin signaling pathways. Conclusions: The results confirmed that oHES could enhance the proliferative and migratory functions of Kfbs by increasing the expression of Col I, fibronectin, and vimentin. oHES promoted keloid formation by increasing Col I expression through TSP-1-mediated Akt and GSK-3β/β-catenin signaling pathways.