title: Loss of RUNX3 increases osteopontin expression and promotes cell migration in gastric cancer.
abstract: Loss of RUNX3 expression is frequently observed in gastric cancer and is highly associated with lymph node metastasis and poor prognosis. However, the underlying molecular mechanisms of gastric cancer remain unknown. In this study, we found that the protein levels of RUNX3 and osteopontin (OPN) are inversely correlated in gastric cancer clinical specimens and cell lines. Furthermore, similar inverse trends between RUNX3 and OPN messenger RNA (mRNA) expression were demonstrated in six out of seven normal-tumor-paired gastric cancer clinical specimens. In addition, low RUNX3 and high OPN expression were associated with poor prognosis in gastric cancer patients. Ectopic expression of green fluorescent protein-RUNX3 reduced OPN protein and mRNA expression in the AGS and SCM-1 gastric cancer cell lines. In contrast, knockdown of RUNX3 in GES-1, a normal gastric epithelial cell line, increased OPN expression. Although three RUNX3-binding sequences have been identified in the OPN promoter region, direct binding of RUNX3 to the specific binding site, -142 to -137bp, was demonstrated by chromatin immunoprecipitation assay. The binding of RUNX3 to the OPN promoter significantly decreased OPN promoter activity. The knockdown of OPN or overexpression of RUNX3 inhibited cell migration in AGS and SCM-1 cells; however, the coexpression of RUNX3 and OPN reversed the RUNX3-reduced migration ability in AGS and SCM-1 cells. In contrast, the knockdown of both RUNX3 and OPN inhibited RUNX3-knockdown-induced migration of GES-1 cells. Together, our data demonstrated that RUNX3 is a transcriptional repressor of OPN and that loss of RUNX3 upregulates OPN, which promotes migration in gastric cancer cells.
authors.affiliation: Institute of Clinical Medicine, National Cheng Kung University Medical College, 138 Sheng-Li Road, Tainan 704, Taiwan.
authors.forename: Hui-Chuan
authors.initials: HC
authors.lastname: Cheng
authors.forename: Yu-Peng
authors.initials: YP
authors.lastname: Liu
authors.forename: Yan-Shen
authors.initials: YS
authors.lastname: Shan
authors.forename: Chi-Ying
authors.initials: CY
authors.lastname: Huang
authors.forename: Forn-Chia
authors.initials: FC
authors.lastname: Lin
authors.forename: Li-Ching
authors.initials: LC
authors.lastname: Lin
authors.forename: Ling
authors.initials: L
authors.lastname: Lee
authors.forename: Chen-Hsun
authors.initials: CH
authors.lastname: Tsai
authors.forename: Michael
authors.initials: M
authors.lastname: Hsiao
authors.forename: Pei-Jung
authors.initials: PJ
authors.lastname: Lu
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000401:mortality / Q000473:pathology*; D017209:Apoptosis; D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D002448:Cell Adhesion; D002465:Cell Movement; D049109:Cell Proliferation; D047369:Chromatin Immunoprecipitation; D050677:Core Binding Factor Alpha 3 Subunit / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D005753:Gastric Mucosa / Q000378:metabolism; D020869:Gene Expression Profiling; D006801:Humans; D008969:Molecular Sequence Data; D009367:Neoplasm Staging; D020411:Oligonucleotide Array Sequence Analysis; D053495:Osteopontin / Q000235:genetics / Q000378:metabolism*; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000378:metabolism / Q000401:mortality / Q000473:pathology*; D015996:Survival Rate
chemical_list: D014408:Biomarkers, Tumor; D050677:Core Binding Factor Alpha 3 Subunit; D012333:RNA, Messenger; C493729:Runx3 protein, human; D053495:Osteopontin