Increased expression of TGF-β1 by 4-hexylresorcinol is mediated by endoplasmic reticulum and mitochondrial stress in human umbilical endothelial vein cells

In our previous study, 4-hexylresorcinol (4HR) increased the expression level of vascular endothelial growth factor in human umbilical vein endothelial cells (HUVECs) via the transforming growth factor-β1 (TGF-β1)-mediated pathway. Endoplasmic reticulum (ER) and mitochondrial stress is a positive regulator of cellular differentiation. As TGF-β1 is a master regulator for cellular differentiation, 4HR treatment may increase TGF-β1 expression via ER stress. In this study, HUVECs were treated using 4HR (1–100 µM) for 24 h. The 4HR treatment increased ER stress-associated markers and mitochondrial stress. Increased TGF-β1 expression by 4HR administration was alleviated by tauroursodeoxycholate (ER stress inhibitor) treatment. Combining these activities with the elevated acetylation level of histone 3 (H3) by 4HR treatment, TGF-β1 expression was increased in HUVECs. Overall, 4HR increased TGF-β1 expression through upregulation of the stress response of ER as well as H3 acetylation in HUVECs.