IL-1β-induced activation of p38 promotes metastasis in gastric adenocarcinoma via upregulation of AP-1/c-fos, MMP2 and MMP9.
BACKGROUND
Interleukin-1β (IL-1β) has been implicated in the progression of gastric adenocarcinoma (GA); however, the molecular mechanisms of action of IL-1β in GA are poorly characterized. P38 and JNK are the major MAPK family members that regulate IL-1β signaling pathways. Here, we investigated the role of both p38 and JNK in IL-1β-induced GA cell migration, invasion and metastatic potential.


METHODS
The effects of IL-1β-induced p38 and JNK activation in GA cells were determined using in vitro Transwell migration and invasion assays of MKN-45 and AGS cells, or an in vivo metastasis assay in nude mice. The IL-1β-induced p38 signaling pathway was further characterized in GA cells. Activation of the IL-1β/p38 signaling pathway was also assessed in human primary GA tissues by immunohistochemistry.


RESULTS
IL-1β-induced activation of p38 increased GA cell migration and invasion in vitro and promoted the metastatic potential of GA cells in vivo; these effects were attenuated by p38 siRNA or the p38 inhibitor SB202190. MMP2 or MMP9 siRNAs and the MMP2/9 inhibitor BiPS also inhibited IL-1β-induced GA cell migration and invasion in vitro. IL-1β-induced p38 activation significantly increased MMP2 and MMP9 mRNA and protein expression and activity. Luciferase reporter assays demonstrated that the activator protein-1 (AP-1) and the AP-1 binding sites of the MMP9 promoter (-670/MMP9) were activated by IL-1β-induced p38 activation. Phospho-p38 was significantly upregulated in human GA tissues (compared to matched non-neoplastic tissues), and significantly associated with lymph node metastasis, and invasion beyond the serosa. Expression of phospho-p38 significantly correlated with IL-1β, MMP2, MMP9, and c-fos expression in both human GA tissues and GA cell metastases in the lungs of nude mice. IL-1β was also capable of activating JNK in GA cells, but activation of JNK was not associated with GA cell migration and invasion. Therefore, IL-1β-induced the migration and invasion in GA cells were regulated by p38, but not by JNK.


CONCLUSIONS
IL-1β-induced p38 activation and the IL-1β/p38/AP-1(c-fos)/MMP2 & MMP9 pathway play an important role in metastasis in GA; this pathway may provide a novel therapeutic target for GA.
Department of Experimental Medicine, Fuzhou General Hospital (Dongfang Hospital), 156 North Xi-er Huan Road, Fuzhou City, Fujian Province 350025, China. huangqj100@126.com.
Qiaojia
Q
Huang
Fenghua
F
Lan
Xiaoting
X
Wang
Yinghao
Y
Yu
Xuenong
X
Ouyang
Feng
F
Zheng
Junyong
J
Han
Youdong
Y
Lin
Yanchuan
Y
Xie
Feilai
F
Xie
Wei
W
Liu
Xiaoli
X
Yang
Han
H
Wang
Lihong
L
Dong
Lie
L
Wang
Jianming
J
Tan
D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D004789:Enzyme Activation / Q000502:physiology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D053583:Interleukin-1beta / Q000378:metabolism*; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D018613:Microscopy, Confocal; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D013274:Stomach Neoplasms / Q000378:metabolism* / Q000473:pathology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D053583:Interleukin-1beta; D016760:Proto-Oncogene Proteins c-fos; D018808:Transcription Factor AP-1; D048051:p38 Mitogen-Activated Protein Kinases; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9