Suppressive Effects of Plumbagin on Invasion and Migration of Breast Cancer Cells via the Inhibition of STAT3 Signaling and Down-regulation of Inflammatory Cytokine Expressions.
OBJECTIVE
The aim of this study was to investigate the effects of plumbagin (PL), a naphthoquinone derived from the medicinal plant plumbago zeylanica, on the invasion and migration of human breast cancer cells.


METHODS
Human breast cancer MDA-MB-231SArfp cells were treated with different concentrations of plumbagin for 24 h. The effects of plumbagin on the migration and invasion were observed by a transwell method. The expressions of IL-1α, IL-1β, IL-6, IL-8, TGF-β, TNFα, MMP-2 and MMP-9 mRNA in MDA-MB-231SArfp cells were detected using Real-Time PCR. MDA-MB-231SArfp cells were treated with plumbagin at different concentrations for 45 minutes. The activation of STAT3 was detected by western blot. Following this analysis, STAT3 in MDA-MB-231SArfp cells was knocked out using specific siRNA. mRNA levels of IL-1α, TGF-β, MMP-2 and MMP-9 were then detected. Consequently, MDA-MB-231SArfp cells were injected intracardially into BALB/c nude mice to construct a breast cancer bone metastatic model. The mice were injected intraperitoneally with plumbagin. Non-invasive in vivo monitoring, X-ray imaging and histological staining were performed to investigate the effects of plumbagin on the invasion and migration of breast cancer cells in vivo.


RESULTS
The in vitro results showed that plumbagin could suppress the migration and invasion of breast cancer cells and down-regulate mRNA expressions of IL-1α, TGF-β, MMP-2 and MMP-9. Western blotting demonstrated that plumbagin inhibited the activation of STAT3 signaling in MDA-MB-231SArfp cells. The inactivation of STAT3 was found to have an inhibitory effect on the expressions of IL-1α, TGF-β, MMP-2 and MMP-9. In vivo studies showed that plumbagin inhibited the metastasis of breast cancer cells and decreased osteolytic bone metastases, as well as the secretion of MMP-2 and MMP-9 by tumor cells at metastatic lesions.


CONCLUSIONS
Plumbagin can suppress the invasion and migration of breast cancer cells via the inhibition of STAT3 signaling and by downregulation of IL-1α, TGF-β, MMP-2 and MMP-9.
Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai 200011, China ; Wendeng Zhenggu Hospital of Shandong Province , Wendeng, Shandong 264400, China.
Wei
W
Yan
Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai 200011, China.
Bing
B
Tu
Department of Gynecology and Obstetrics, Wendeng Center Hospital of Weihai City , Weihai, Shandong 264400, China.
Yun-Yun
YY
Liu
Department of Pharmacy, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai, 200011 China.
Ting-Yu
TY
Wang
Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai 200011, China.
Han
H
Qiao
Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai 200011, China.
Zan-Jing
ZJ
Zhai
Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai 200011, China.
Hao-Wei
HW
Li
Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai 200011, China.
Ting-Ting
TT
Tang
breast cancer; invasion; migration; plumbagin