ILF3 promotes gastric cancer proliferation and may be used as a prognostic marker

Abstract

Interleukin enhancer‑binding factor 3 (ILF3) may function as a transcriptional coactivator and has been reported to be involved in tumor proliferation and metastasis; however, its role and clinical value in gastric cancer (GC) remains unclear. To understand the value of ILF3 in GC, a total of 80 matched samples selected from GC tissues and the adjacent mucosa were used to evaluate the expression of ILF3 and its association with clinical characteristics. Furthermore, its biological functions and mechanisms were investigated using SGC‑7901 and BGC823 cell lines. Immunohistochemistry demonstrated that the positive expression rates of ILF3 in GC tissue were higher compared with those in adjacent mucosa (P<0.05). Significantly overexpressed ILF3 was detected in BGC823 and SGC7901 cells, and the MTT results demonstrated decreased cell activity after ILF3 expression was inhibited. The proportions of cells in the G0/G1 phase increased, while the number of cells in the G2/M phase decreased, and the expression of the genes associated with proliferation varied following inhibition of ILF3 (P<0.05). Positive expression of ILF3 was associated with a poor prognosis for patients with GC, and was an independent risk factor for GC (P<0.05). In conclusion, ILF3 is involved in the deterioration of GC by promoting proliferation of GC cells, and ILF3 protein detection may assist in the prediction of the prognosis of patients with GC.

Figure 1.

ILF3 protein expression in tissues of gastric cancer and adjacent mucosal tissues (IHC, ×400 magnification). ILF3 protein expression was detected by IHC, predominantly in the cytoplasm with infrequent cell membrane expression. ILF3 positive staining in gastric cancer tissues was increased compared with that that in cancer-adjacent mucosa. ILF3, interleukin enhancer-binding factor 3; IHC, immunohistochemistry.

Figure 2.

Expression of ILF3 protein in gastric cancer cell lines and the gastric epithelial cell line GES-1 (western blotting). In the western blot analysis, ILF3 protein exhibited significantly higher expression in gastric cancer cell lines compared with GES-1. In particular, BGC823 was verified to have the highest expression of ILF3 protein, followed by SGC7901 and AGS. Lane 1, BGC823; lane 2, AGS; lane 3, SGC7901; lane 4, GES-1. *P<0.01 vs. GES-1. ILF3, interleukin enhancer-binding factor 3.

Figure 3.

Effect of ILF3-siRNA treatment on ILF3 expression in BGC823 and SGC7901 cells (reverse transcription-quantitative polymerase chain reaction and western blotting). A total of 40 nmol/l of ILF3-siRNA or negative control siRNA was transfected to BGC823 and SGC7901 cells respectively. The results demonstrated that the ILF3 (A) mRNA and (B) protein expression in BGC823 cells, and the (C) mRNA and (D) protein expression in SGC7901 cells, were significantly decreased compared with the respective negative control siRNA groups. *P<0.01 vs. respective negative control group. siRNA, small interfering RNA; ILF3, interleukin enhancer-binding factor 3.

Figure 4.

Effect of ILF3-siRNA transfection on the BGC823 and SGC7901 cell cycle. The FCM results demonstrated a larger proportion of cells in the G0/G1 phase in the ILF3-siRNA group compared with that in the negative control group, while the proportion of cells in the G2/M phase in the former group was smaller than in the control. (A) FCM results of the ILF3-siRNA transfection and negative control groups for BGC823 cells. (B) FCM results of the ILF3-siRNA transfection and negative control groups for SGC7901 cells. FCM, flow cytometry; siRNA, small interfering RNA; ILF3, interleukin enhancer-binding factor 3.

Figure 5.

ILF3-siRNA treatment impacts upon p16, p21 and Cyclin D1 expression in BGC823 and SGC7901 cells. Using RT-qPCR and western blotting, in BGC823 and SGC7901 cells transfected with ILF3-siRNA, the mRNA and protein expression of p16, p21 and Cyclin D1 were significantly lower than that in the negative control group. For BGC823 cells: (A) Histogram of RT-qPCR results; (B) histogram of western blotting results; (C) representative image of SDS-PAGE. For SGC7901 cells: (D) Histogram of RT-qPCR results; (E) histogram of western blotting results; (F) representative image of SDS-PAGE. *P<0.01 vs. respective negative control group. RT-qPCR, reverse transcription-quantitative polymerase chain reaction; siRNA, small interfering RNA; ILF3, interleukin enhancer-binding factor 3.

Figure 6.

Kaplan-Meier survival curve for ILF3 protein expression associated with the prognosis of patients with gastric cancer. The results indicated a lower survival rate in participants with positive ILF3 expression compared with those without expression (χ²=15.683; P<0.001). Cum, cumulative; ILF3, interleukin enhancer-binding factor 3.