[FJX1 overexpression is associated with poor prognosis and promotes gastric cancer proliferation via the PI3K/AKT signaling pathway]

Abstract

Objective: To investigate the expression of four-jointed box kinase 1 (FJX1) in gastric cancer (GC), its correlation with survival outcomes of the patients, and its role in GC progression.

Methods: The expression level of FJX1 in GC tissues and normal gastric mucosal tissues and its correlation with the survival outcomes of GC patients were analyzed using TCGA and GEO database GC cohort. Immunohistochemistry was used to detect FJX1 expression level in clinical specimens of GC tissue, and its correlations with the patients' clinicopathological parameters and prognosis were analyzed. Bioinformatic analysis was performed to identify the potential pathways of FJX1 in GC. The effects of FJX1 overexpression or FJX1 silencing on GC cell proliferation and expressions of proliferation-related proteins, PI3K, AKT, p-PI3K, and p-AKT were evaluated using CCK-8 assay and Western blotting. The effect of FJX1 overexpression on GC cell tumorigenicity was evaluated in nude mice.

Results: GC tissues showed significantly higher expressions of FJX1 mRNA and protein compared with normal gastric mucosa tissues (P < 0.05). The high expression of FJX1 was associated with poor prognosis of GC patients (P < 0.05) and served as an independent risk factor for poor survival outcomes in GC (P < 0.05). FJX1 was expressed mainly in the cytoplasm of GC cells in positive correlation with Ki67 expression (R=0.34, P < 0.05), and was correlated with CA199 levels, depth of tumor infiltration and lymph node metastasis of GC (P < 0.05). In the cell experiment, FJX1 level was shown to regulate the expressions of Ki67 and PCNA and GC cell proliferation (P < 0.05). Gene set enrichment analysis indicated that the PI3K/AKT pathway potentially mediated the effect of FJX1, which regulated the expressions of PI3K and AKT and their phosphorylated proteins. In nude mice, FJX1 overexpression in GC cells significantly promoted the growth of the transplanted tumors (P < 0.05).

Conclusion: FJX1 is highly expressed in GC tissues and is correlated with poor prognosis of GC patients. FJX1 overexpression promotes GC cell proliferation through the PI3K/AKT signaling pathway, and may serve as a potential prognostic biomarker and therapeutic target for GC.

Keywords: Gastric cancer; four-jointed box kinase 1; proliferation; survival prognosis.

图 1

FJX1在胃癌中的表达情况 Expression of FJX1 in GC tissues. A: Expression of FJX1 in pan-cancer tissues and normal tissues. B: Expression of FJX1 in GC samples of TCGA cohort. C: FJX1 expression in paired GC samples of TCGA cohort. D: ROC analysis of FJX1 in GC samples of TCGA cohort. E: Expression of FJX1 in GC samples of GSE66229 cohort. F: FJX1 expression in paired GC samples of GSE66229 cohort. G: ROC analysis of FJX1 in GC samples of GSE66229 cohort.

图 2

FJX1在胃癌中的预后价值分析 Analysis of the prognostic value of FJX1 in GC. A: Analysis of FJX1 expression and prognosis of GC patients in the TCGA cohort. B: Multifactorial COX analysis of risk factors affecting the prognosis of GC patients in the TCGA cohort. C: Analysis of FJX1 expression and prognosis of GC patients in the GSE84437 cohort. D: Multifactorial COX analysis of risk factors affecting the prognosis of GC patients in the GSE84437 cohort. ^*P < 0.05, ^**P < 0.01.

图 3

FJX1在胃癌中的蛋白表达以及预后价值 Protein expression of FJX1 in GC and its prognosis value. A: Immunohistochemical detection of FJX1 and Ki67 expression in GC and normal tissues. B: Differential analysis of FJX1 protein expression in GC and normal tissues. C: Correlation analysis of protein expression levels of FJX1 and KI67 in GC tissues. D: Survival analysis of FJX1 in the BBMC cohort. E: Multifactorial COX analysis of FJX1 in the BBMC cohort. ^*P < 0.05.

图 4

FJX1在胃癌中的功能富集分析 Functional enrichment analysis of FJX1 in GC. A: GO analysis of FJX1 in GC. B: KEGG analysis of FJX1 in GC. C: GSEA analysis of FJX1 expression and PI3K-Akt signaling pathway. D: Correlation analysis of FJX1 with key genes of PI3K/AKT signaling pathway in gastric cancer.

图 5

FJX1调控胃癌细胞增殖 FJX1 regulates gastric cancer cell proliferation. A: Validation of FJX1 overexpression and FJX1 silencing in MGC803 cells. B: Validation of FJX1 overexpression and FJX1 silencing in SGC7901 cells. C: FJX1 regulates the expression of proliferation-associated proteins Ki67 and PCNA in MGC803 cells. D: Cell proliferation was determined by CCK8 assay in MGC803 cells. E: FJX1 regulates the expression of proliferation-associated proteins Ki67 and PCNA in SGC7901 cells. F: Cell proliferation was determined by CCK8 assay in SGC7901 cells. ^*P < 0.05, ^**P < 0.01 vs Vector group, ^##P < 0.01 vs OE-FJX1 group.

图 6

FJX1调控胃癌细胞中的PI3K/AKT信号通路 FJX1 regulates the PI3K/AKT signaling pathway in gastric cancer cells. A: Detection of PI3K, AKT protein and phosphorylated protein expression in FJX1 differentially expressed MGC803 cells by WB. B: Differential analysis of IOD values of phosphorylated PI3K and phosphorylated AKT protein expression in MGC803 cells. C: Detection of PI3K, AKT protein and phosphorylated protein expression in FJX1 differentially expressed SGC7901 cells by WB. D: Differential analysis of IOD values of phosphorylated PI3K and phosphorylated AKT protein expression in SGC7901 cells. ^*P < 0.05, ^**P < 0.01 vs Vector group, ^##P < 0.01 vs OE-FJX1 group.

图 7

FJX1在移植瘤模型中促进肿瘤生长 FJX1 promotes tumor growth in an implantation tumor model. A: Implantation tumor growth of MGC803 cells in Vector group, OE-FJX1 group and sh-FJX1 group. B: Comparison of tumor weight in Vector group, OE-FJX1 group and sh-FJX1 group. C: Comparison of tumor volume in Vector group, OE-FJX1 group and sh-FJX1 group. ^*P < 0.05, ^**P < 0.01 vs Vector group, ^##P < 0.01 vs OE-FJX1 group.