Diosmetin prevents TGF-β1-induced epithelial-mesenchymal transition via ROS/MAPK signaling pathways.
OBJECTIVE
Epithelial-mesenchymal transition (EMT) plays a critical role in airway repair and remodeling in many respiratory diseases such as asthma and pulmonary fibrosis. The flavone aglycone, diosmetin, possesses anti-remodeling activity in a murine model of chronic asthma, but little is known about its effects on EMT. Herein, we investigated whether diosmetin inhibits transforming growth factor-β1 (TGF-β1)-induced EMT with underlying mechanisms in human bronchial epithelial (HBE) cells.


METHODS
HBE cells were incubated with TGF-β1 (10ng/ml), either alone or in combination with diosmetin for indicated times. We measured reactive oxygen species (ROS) levels using FACScan and immunofluorescent assays. We assessed protein expression of NADPH oxidase 4 (NOX4), superoxide dismutase (SOD), catalase, Akt, Erk, p38, and phosphorylation levels of Akt, Erk and p38 by Western blot analysis.


RESULTS
TGF-β1 promoted EMT and ROS generation in HBE cells. Diosmetin significantly suppressed TGF-β1-induced increases in cell migration and altered N-cadherin, E-cadherin, and α-smooth muscle actin expression. In addition, diosmetin prevented TGF-β1-induced intracellular ROS generation, down-regulated NOX4, and up-regulated SOD and catalase expression. Furthermore, diosmetin remarkably inhibited TGF-β1-induced phosphorylation of phosphoinositide 3-kinase (PI3K)/Akt and mitogen activated protein kinase (MAPK) pathways in HBE cells.


CONCLUSIONS
Our results demonstrate for the first time that diosmetin alleviates TGF-β1-induced EMT by inhibiting ROS generation and inactivating PI3K/Akt and MAPK pathways. Our findings revealed a new role for diosmetin in reducing airway remodeling and fibrogenesis.
Department of Respiratory & Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China.
Ai
A
Ge
Department of Respiratory & Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China.
Yuan
Y
Ma
Department of Respiratory & Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China; Department of Respiratory & Critical Care Medicine, The Affiliated Hospital of Xuzhou Medical University, 99 Huaihai West Road, Xuzhou, Jiangsu 221000, China.
Ya-Nan
YN
Liu
Department of Respiratory & Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China; Department of Respiratory & Critical Care Medicine, The Second People's Hospital of Wuhu, 263 Jiuhuashan Road, Wuhu, Anhui 241001, China.
Ye-Shan
YS
Li
Department of Respiratory & Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China.
Hao
H
Gu
Department of Respiratory & Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China.
Jia-Xiang
JX
Zhang
Department of Respiratory & Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China.
Qin-Xue
QX
Wang
Department of Respiratory & Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China. Electronic address: zeng_xiao_ning@hotmail.com.
Xiao-Ning
XN
Zeng
Department of Respiratory & Critical Care Medicine, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China. Electronic address: huangmao6114@126.com.
Mao
M
Huang
D002460:Cell Line; D058750:Epithelial-Mesenchymal Transition / Q000502:physiology*; D005419:Flavonoids / Q000502:physiology*; D006801:Humans; D020935:MAP Kinase Signaling System; D010766:Phosphorylation; D017382:Reactive Oxygen Species / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000502:physiology*
D005419:Flavonoids; D017382:Reactive Oxygen Species; D053773:Transforming Growth Factor beta1; C039602:diosmetin
Diosmetin; EMT; MAPK; ROS; TGF-β1