The prognostic value and biological significance of gap junction beta protein 2 (GJB2 or Cx26) in cervical cancer

Abstract

Objective: To evaluate the prognostic value and explore the biological significance of gap junction protein beta 2 (GJB2 or Cx26) in cervical cancer (CC).

Methods: We first compared GJB2 expression between CC and normal tissues using public databases and immunohistochemistry (IHC). Based on The Cancer Genome Atlas data (TCGA cohort, n = 304) and tissue microarray samples (OBC cohort, n = 111), we explored the prognostic value of GJB2 for CC patients using bioinformatics analysis and IHC scoring. To explore the biological significance of GJB2, Gene set enrichment analysis (GSEA) and Gene Ontology (GO) were performed. The impact of GJB2 on the immune microenvironment was analyzed by CIBERSORTx and ESTIMATE algorithms. We finally investigated the relationship between GJB2 and drug sensitivity based on the Genomics of Drug Sensitivity in Cancer (GDSC).

Results: The expression of GJB2 was significantly increased in CC over normal tissues. Both the TCGA and OBC cohort found that patients with high GJB2 expression had shorter overall survival (OS) time, and high GJB2 expression was the independent risk factor for prognosis (TCGA: HR, 2.566; 95% CI, 1.066-6.180; p = 0.036; OBC: HR, 2.198; 95% CI, 1.019-4.741; p = 0.045). GJB2 was correlated with patient clinical factors such as tumor size and differentiation grade. The p53 signaling pathway and toll-like receptor pathway may be regulated by GJB2. The abundance of various immune cells was significantly different between the low and high GJB2 expression groups. The ImmuneScore was significantly increased in the high GJB2 expression group. In addition, the expression level of GJB2 was positively correlated with the natural log of the half-maximal inhibitory concentration (LN_IC50) value of cisplatin/paclitaxel (Spearman r = 0.238/0.153, p < 0.001).

Conclusion: GJB2 can serve as a potential prognostic marker of poor survival and a therapeutic target in CC. Moreover, GJB2 may affect the immune microenvironment and is correlated with chemoresistance.

Keywords: GJB2; cervical cancer; chemoresistance; immune cell abundance; prognostic marker.

Figure 1

The expression of GJB2 and its association with clinical factors and survival analysis based on the TCGA database. (A) The result of GEPIA; (B) GJB2 expression in CC and its paracancerous tissue; (C) Histology; (D) FIGO stage; (E) Impact of GJB2 expression on overall survival in CC; (F) Forest plot for the univariate and multivariate Cox proportional hazard regression model. TCGA, The Cancer Genome Atlas; CC, Cervical cancer; SCC, Squamous cell carcinoma; ACC, Adenocarcinomas; FIGO, The International Federation of Gynecology and Obstetrics; HR, Hazard ratio. *p < 0.05, ***p < 0.001.

Figure 2

Survival analysis based on the OBC data. (A) The representative images of high GJB2 and low GJB2 expression; (B) Impact of GJB2 expression on overall survival in CC; (C) Forest plot for the univariate and multivariate Cox proportional hazard regression model. OBC, Outdo Biotech. Co., Ltd.; HR, Hazard ratio.

Figure 3

Gene set enrichment analysis and immune cell abundance analysis. (A) A merged enrichment plot including the enrichment score and gene sets. 12 pathways are shown here; (B) Proportion of immune cells in the low and high GJB2 expression group; (C) Immune cell abundance analysis between the low and high GJB2 expression group. *p < 0.05, ***p < 0.001, ****p < 0.0001. ns: not significant.

Figure 4

Chemotherapy drugs sensitivity analysis. The relationship between GJB2 expression and LN_IC50 values of (A) cisplatin, (B) paclitaxel, and (C) 5-fluorouracil. LN_IC50 value: Natural log of the half-maximal inhibitory concentration. **p < 0.01, ***p < 0.001.