Differentially expressed long noncoding RNAs and regulatory mechanism of LINC02407 in human gastric adenocarcinoma

Figure 1 Differentially expressed long noncoding RNAs between tumor tissue and adjacent nontumor tissue samples. A: Volcano map for differentially expressed long noncoding RNAs (lncRNAs); B: Heat map for differentially expressed lncRNAs. FDR: False discovery rate; FC: Fold change.

Figure 2 Kaplan-Meier survival curves for three long noncoding RNAs associated with overall survival. Kaplan-Meier analysis and log-rank test were performed to estimate the relations between (A) LINC02407, (B) OVAAL, and (C) LINC00973 expression and the overall survival of gastric cancer (GC) patients. OVAAL: Ovarian adenocarcinoma amplified long non-coding RNA.

Figure 3 Association between long noncoding RNA expression and survival. A: Forest plot showing the hazard ratio (HR) and P value for overall survival (OS) in patients with gastric cancer (GC) based on long noncoding RNA (lncRNA) high vs low expression; B: Kaplan-Meier analysis of OS according lncRNA expression levels; C: Receiver operating characteristic curve analysis based on a forest plot showing the hazard ratio and OS; D: HR heatmap representing associations between LIN01614, LIN01537, LIN02407, C15orf54, and CYMP-AS1 expression and OS in patients with different clinicopathological characteristics. Only HRs with P values less than 0.05 are shown. HR: Hazard ratio; ROC: Receiver operating characteristic; AUC: Area under curve.

Figure 4 LINC02407 is upregulated in clinical gastric cancer specimens and cell lines. A: The relative expression of LINC02407 determined by qRT-PCR in 20 paired gastric cancer tissues and adjacent normal tissues; B: The relative expression of LINC02407 determined by q-RT-PCR in six cell lines (HaCaT, GES-1, MGC-803, MKN45, SGC-7901, and HGC-27). Data are reported as the mean ± SD. ^aP < 0.05, ^bP < 0.01, and ^eP < 0.001 for between-group comparisons.

Figure 5 Effect of LINC02407 on HGC-27 cells. A: Quantitative real-time polymerase chain reaction to determine LINC02407 relative expression in LINC02407-overexpressing lentivirus, overexpression-control, si-LINC02407, and si-NC-transfected HGC-27 cells; B: Determination of proliferation of different groups of HGC-27 cells; C: Hoechst staining assay of different groups of HGC-27 cells; D: Flow cytometry analysis of apoptosis rates of different groups of HGC-27 cells; E: Wound healing assay of different groups of HGC-27 cells. Data are reported as the mean ± SD. ^aP < 0.05, ^bP < 0.01, and ^eP < 0.001 for between-group comparisons. NC: Negative control.

Figure 6 Hsa-miR-6845-5p and hsa-miR-4455 have negative effects on gastric cancer. A: Luciferase reporter assay verifying hsa-miR-6845-5p and hsa-miR-4455 as direct targets of hsa-miR-6845-5p and hsa-miR-4455; B: Determination of the effects of hsa-miR-6845-5p-mimic and hsa-miR-4455-mimic on cell viability in HGC-27 cells; C: Evaluation of the influence of hsa-miR-6845-5p-mimic and hsa-miR-4455-mimic on HGC-27 cell apoptosis; D: Evaluation of the effect of hsa-miR-6845-5p-mimic and hsa-miR-4455-mimic on invasion of HGC-27 cells. Data are reported as the mean ± SD. ^aP < 0.05, ^bP < 0.01, and ^eP < 0.001 for between-group comparisons. NC: Negative control.

Figure 7 LINC02407 influences gastric cancer through the LINC02407-miR-6845-5p and miR-4455-adhesion G protein-coupled receptor D1 pathways. A: Sankey diagram for the competing endogenous RNA network in LINC02407. This Sankey plot shows the quantity of evidence for LINC02407 on the left-hand side, miR-6845-5p and miR-4455 in the middle, and the quantity of evidence for potential target mRNAs on the right-hand side of the plot. Each rectangle represents a gene, and the size of the rectangle represents the degree of connection of each gene; B: Western blot assay of adhesion G protein-coupled receptor D1, cholinergic receptor nicotinic delta, IGLON5, KRI1, and troponin I1 proteins differentially expressed in HGC-27 cells under different treatments. Data are reported as the mean ± SD. ^aP < 0.05, ^bP < 0.01, and ^eP < 0.001 for between-group comparisons. NC: Negative control; ADGRD1: Adhesion G protein-coupled receptor D1; CHRND: Cholinergic receptor nicotinic delta; IGLON5: IgLON family member 5; TNNI1: Troponin I1; LncRNA: Long noncoding RNA; miRNA: MicroRNA.