Heat Shock Protein 90 Inhibitor Decreases Collagen Synthesis of Keloid Fibroblasts and Attenuates the Extracellular Matrix on the Keloid Spheroid Model

Abstract

Background: The 90-kDa heat-shock protein (heat-shock protein 90) is an abundant cytosolic chaperone, and inhibition of heat-shock protein 90 by 17-allylamino-17-demethoxygeldanamycin (17-AAG) compromises transforming growth factor (TGF)--mediated transcriptional responses by enhancing TGF- receptor I and II degradation, thus preventing Smad2/3 activation. In this study, the authors evaluated whether heat-shock protein 90 regulates TGF- signaling in the pathogenesis and treatment of keloids. Methods: Keloid fibroblasts were treated with 17-AAG (10 M), and mRNA levels of collagen types I and III were determined by real-time reverse- transcriptase polymerase chain reaction. Also, secreted TGF-1 was assessed by enzyme-linked immunosorbent assay. The effect of 17-AAG on protein levels of Smad2/3 complex was determined by Western blot analysis. In addition, in 17-AAG-treated keloid spheroids, the collagen deposition and expression of major extracellular matrix proteins were investigated by means of Masson trichrome staining and immunohistochemistry. Results: The authors found that heat-shock protein 90 is overexpressed in human keloid tissue compared with adjacent normal tissue, and 17-AAG decreased mRNA levels of type I collagen, secreted TGF-ss 1, and Smad2/3 complex protein expression in keloid fibroblasts. Masson trichrome staining revealed that collagen deposition was decreased in 17-AAG-treated keloid spheroids, and immunohistochemical analysis showed that expression of collagen types I and III, elastin, and fibronectin was markedly decreased in 17-AAG-treated keloid spheroids. Conclusion: These results suggest that the antifibrotic action of heat-shock protein 90 inhibitors such as 17-AAG may have therapeutic effects on keloids.