Fig 2: Depletion of ELK3 decreases the migration and invasion of SNU638 cell line in E-cadherin independent manner. (A) ELK3 mRNA levels in SNU638 cells transfected with siCon or siELK3. Error bars represent the standard deviation; **** p < 0.0001 (student’s t-test). (B) ELK3 protein levels in SNU638 cells transfected with siCon or siELK3. The values indicate the signal intensities of ELK3 relative to GAPDH. (C) Representative images showing cell migration (top two panels) and cell invasion (bottom two panels) of SNU638 cells transfected with siCon or siELK3. Scale bar, 200 µm. Bar graphs indicate the number of migrated and invaded cells, respectively. Error bars represent the standard deviation; * p < 0.05 and ** p < 0.01 (student’s t-test). (D) Epithelial marker (E-cadherin), mesenchymal marker (Fibronectin), and ELK3 protein expression in SNU638 cells transfected with siCon or siELK3. Bar graphs indicate the quantified levels of each protein, in relative scales. Error bars represent the standard deviation; ** p < 0.01 (student’s t-test). ELK3, ETS transcription factor ELK3; si, small interfering RNA; Con, control.

Fig 3: ETS transcription factor ELK3 (ELK3) expression pattern in various gastric cancer cell lines. (A) ELK3 expression in gastric cancer cell lines from the Cancer Dependency Map (DepMap) database. (B) ELK3 mRNA expression in five gastric cancer cell lines, measured by reverse transcription-quantitative PCR. Error bars represent the standard deviation; ** p < 0.01 (one-way ANOVA). (C) ELK3 protein levels in five gastric cancer cell lines. The values indicate the signal intensities of ELK3 relative to GAPDH.

Fig 4: ELK3 controls extracellular matrix (ECM) remodeling-related genes to control cell migration. (A) Gene set enrichment analysis of RNA sequencing data from SNU638 cells transfected with siCon or siELK3. Cell adhesion-related genes were positively enriched and cell junction disassembly-related genes were negatively enriched in SNU638 cells transfected with siELK3. (B) Pie graphs showing biological pathways in ELK3-depleted SNU638 cells. Numbers indicate the number of genes in each biological pathway. (C) Heatmap analysis of genes associated with cell migration and cell adhesion. (D) Bar graph showing the Database for Annotation, Visualization, and Integrated Discovery (DAVID) annotation of genes involved in cell migration and cell adhesion. (E) Map data of Search Tool for the Retrieval of Interacting Genes analysis (STRING). The thickness of the lines represents the confidence of the interaction.

Fig 5: Expression levels of miR-200a and ELK3 mRNA are negatively correlated in breast cancer cells and patient samples. (A) Heat map of miR-200a and ELK3 mRNA expression in breast cancer cell lines. The blue dots indicate the normal-like/claudin-low breast cancer subtype and the red dots indicate the luminal breast cancer subtype. (B) Correlation between miR-200a and ELK3 mRNA expression in breast cancer patients (n = 747). Luminal-A subtype (n = 415) and TNBC subtype (n = 118) samples were selected based on the receptor expression phenotype. All data were downloaded from the TCGA database.