title: Raf kinase inhibitor protein inhibits esophageal cancer cell invasion through downregulation of matrix metalloproteinase expression.
abstract: Esophageal cancer is the eighth most common malignant tumor in the world and is a common cause of tumor-related death. The development of esophageal cancer is a complex process involving many pathogenetic factors, multiple stages and accumulation of multiple gene mutations and interactions. This study aimed to investigate the effects of Raf kinase inhibitor protein (RKIP) on the proliferation, apoptosis and invasion of TE-1 esophageal cancer cells. Surgical specimens from esophageal cancer patients were classified into esophageal cancer tissues, tumor-adjacent tissues and normal esophageal tissues. The tissues were fixed in 4% paraformaldehyde solution for hematoxylin and eosin and immunohistochemical staining. RKIP expression in esophageal tissues was detected by immunohistochemical staining. The esophageal cancer cell line TE-1 was exposed to four different viruses: RKIP-RNAi-AD, NC-RNAi-GFP-AD, RKIP-AD and GFP-AD. Cell proliferation was detected by MTT assay and cell apoptosis was detected by flow cytometry. Cell invasion was determined by a Transwell coated with Matrigel. RKIP, phospho-RKIP, Raf-1, phospho-Raf-1, ERK1/2, phospho-ERK1/2, GRK-2 and GAPDH expression was assayed by western blotting. LIN28 and MMP-14 mRNA was assayed by qPCR. The results showed that RKIP expression was reduced in esophageal cancer tissues in comparison with expression in normal esophageal epithelium tissues and tumor-adjacent tissues. Reduced RKIP expression was associated with lymph node or distant metastasis in esophageal cancer. RKIP inhibited the invasive and metastatic abilities of esophageal cancer cell line TE-1 by downregulating mRNA expression of LIN28 and MMP-14. RKIP had no effect on the MAPK signaling pathway in the esophageal cancer cell line TE-1, but was involved in the G protein-coupled signaling pathway. Our findings clearly demonstrate that RKIP inhibits esophageal cancer cell invasion by downregulating the expression of GRK-2, LIN28 and MMP-14.
authors.affiliation: Department of Gastroenterology, The Second Hospital of Hebei Medical University, Hebei Key Laboratory of Gastroenterology, Hebei Institute of Gastroenterology, Shijiazhuang, Hebei 050000, P.R. China.
authors.forename: Dongqiang
authors.initials: D
authors.lastname: Zhao
authors.forename: Junji
authors.initials: J
authors.lastname: Ma
authors.forename: Junli
authors.initials: J
authors.lastname: Shi
authors.forename: Lijuan
authors.initials: L
authors.lastname: Cheng
authors.forename: Fangfang
authors.initials: F
authors.lastname: Li
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Jiang
authors.forename: Huiqing
authors.initials: H
authors.lastname: Jiang
mesh_terms: D017209:Apoptosis; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015536:Down-Regulation; D004938:Esophageal Neoplasms / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D054769:G-Protein-Coupled Receptor Kinase 2 / Q000378:metabolism*; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) / Q000378:metabolism; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D053511:Matrix Metalloproteinase 14 / Q000378:metabolism*; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D049488:Phosphatidylethanolamine Binding Protein / Q000235:genetics / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins / Q000378:metabolism*
chemical_list: C000715187:Lin28A protein, human; C511482:PEBP1 protein, human; D049488:Phosphatidylethanolamine Binding Protein; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating); D019908:Proto-Oncogene Proteins c-raf; C496567:GRK2 protein, human; D054769:G-Protein-Coupled Receptor Kinase 2; D048049:Extracellular Signal-Regulated MAP Kinases; D053511:Matrix Metalloproteinase 14