FAF1 mRNA在胃癌组织中的表达及其与幽门螺杆菌感染的相关性

Mechanism for Helicobacter pylori infection to regulate Fas-associated factor 1 expression through nuclear factor-κB signaling pathway

AIM: To explore the influence of Helicobacter pylori (H. pylori) infection on human gastric cancer cells overexpressing Fas-associated factor 1 (FAF1) after knockout of IKKβ or p65 of the nuclear factor-κB (NF-κB) pathway, in order to further clarify the mechanism of H. pylori in gastric carcinogenesis.

METHODS: Lentivirus vectors carrying siRNA targeting IKKβ or p65 were constructed (LV-IKKβ-RNAi, LV-p65-RNAi) and used to transfecting human gastric cancer cells HGC-27 overexpressing FAF1. IKKβ, p65, and FAF1 mRNA and protein expression was detected by real-time PCR and Western blot before and after transfection. CCK8 assay was applied to detect cell proliferation after transfection. The transfected cells were infected with H. pylori culture filtrate, and real-time PCR and Western blot were applied to detect IKKβ, p65 and FAF1 expression before and after H. pylori infection.

RESULTS: LV-IKKβ-RNAi, LV-p65-RNAi and negative control (LV-NC-RNAi) were transfected into HGC-27 cells overexpressing FAF1 successfully. After transfection for 72 h, the expression of IKKβ and p65 mRNA and protein in the LV-IKKβ-RNAi group and LV-p65-RNAi group were significantly lower than that in the LV-NC-RNAi group and untransfected group (P < 0.01). There was no statistically significant difference in the expression of FAF1 mRNA and protein in the four groups (P > 0.05). The proliferation of cells in the LV-IKKβ-RNAi group and LV-p65-RNAi group increased. H. pylori culture filtrate was used to infect different groups of cells. There was no statistically significant difference in the expression of IKKβ and p65 mRNA and protein in the LV-IKKβ-RNAi group and LV-p65-RNAi group before and after H. pylori infection (P > 0.05), but the expression of IKKβ and p65 mRNA and protein in the LV-NC-RNAi group and untransfected group after H. pylori infection was significantly higher than that before H. pylori infection (P < 0.01). There was no statistically significant difference in the expression of FAF1 mRNA and protein in the LV-IKKβ-RNAi group and LV-p65-RNAi group before and after H. pylori infection (P > 0.05), but the expression of FAF1 mRNA and protein in the LV-NC-RNAi group and untransfected group after H. pylori infection was significantly lower than that before H. pylori infection (P < 0.01).

CONCLUSION: H. pylori infection might regulate FAF1 expression through the NF-κB signaling pathway, and downregulation of FAF1 could lead to gastric carcinogenesis.

Effects of FAF1 overexpression on proliferation and apoptosis of gastric carcinoma HGC-27 cells

AIM: To investigate the influence of the overexpression of Fas-associated factor 1 (FAF1) on cell proliferation and apoptosis in human gastric cancer cell line HGC-27 to explore the relationship between FAF1 and gastric cancer.

METHODS: HGC-27 cells were divided into three groups: a negative control group, an empty vector transfection group (those transfected with empty vector particles 1.0 × 10⁸ TU/mL), and a FAF1 overexpression group (those transfected with recombinant FAF1 lentiviral particles 1.0 × 10⁸ TU/mL). Transfection efficiency was detected by laser scanning confocal microscopy. Protein expression level of FAF1 was detected by Western blot. Changes of cell ultrastructure were detected by transmission electron microscopy. Cell cycle distribution and apoptosis were observed by flow cytometry. Cell proliferation was detected by MTT assay.

RESULTS: The transfection efficiency was greater than 95% according to the green fluorescence. The expression of FAF1 protein was significantly higher in the FAF1 overexpression group than in the two control groups. The cell ultrastructure was normal in the two control groups; however, in the FAF1 overexpression group, cell nuclei split into pieces and apoptotic bodies and vacuoles formed. Overexpression of FAF1 inhibited HGC-27 cell growth, induced cell apoptosis, and changed the cell cycle progression. Compared to the negative control group and empty vector transfection group, cell doubling time was significantly extended, cell apoptosis was significantly increased (84.66% ± 5.92% vs 4.60% ± 3.80%, 7.32% ± 3.82%, both P < 0.05), the percentage of cells in G₀/G₁ phase was significantly decreased (46.43% ± 2.43% vs 54.93% ± 3.5%, 54% ± 0.3%, both P < 0.05), and the percentage of cells in G₂/M phase was significantly increased (29.78% ± 3.91% vs 19.33% ± 3.82%, 20.93% ± 2.46%, both P < 0.05) in the FAF1 overexpression group.

CONCLUSION: FAF1 overexpression could inhibit cell growth, induce cell apoptosis, and change cell cycle progression.