SNRPB2: a prognostic biomarker and oncogenic driver in esophageal cancer via β-catenin/c-Myc signaling

Abstract

Background: The SNRPB2 gene encodes Small Nuclear Ribonucleoprotein Polypeptide B2, a crucial component involved in RNA splicing processes. While SNRPB2 dysregulation has been observed in various cancers, its role in esophageal cancer (ESCA) remains unclear.

Methods: The mRNA level of SNRPB2 in ESCA was evaluated in combination with TCGA, GTEX, and GEO databases. The prognostic value of SNRPB2 was assessed using Kaplan-Meier analysis. Immunohistochemistry (IHC) was employed to confirm the expression of the SNRPB2 protein in tumor tissues from clinical samples. The biological functions of SNRPB2 were assessed in vitro cell assay and in vivo tumor models. The molecular mechanisms were determined by correlation and gene set enrichment analysis. Western blot experiments validated involvement in signaling pathways.

Results: Our findings unveiled that SNRPB2 was upregulated at both mRNA and protein levels in ESCA, which was associated with the pathological progression of the disease. Additionally, SNRPB2 served as a robust prognostic biomarker, implicated in driving oncogenic functions in ESCA. It facilitated cell proliferation, migration, and invasion, transitioned the cell cycle, and inhibited apoptosis. Mechanistically, SNRPB2 activated genes associated with the β-catenin/c-Myc signaling pathway, such as β-catenin, c-Myc, CCNA2, CCNB1, CDK1, and CDK2. This activation also regulated the epithelial-to-mesenchymal transition (EMT), thereby facilitating the progression of ESCA.

Conclusion: Our findings demonstrate that SNRPB2 contributes to ESCA progression by regulating the β-catenin/c-Myc axis, suggesting its potential as a prognostic biomarker and therapeutic target for ESCA patients.

Keywords: EMT; SNRPB2; esophageal cancer; prognostic marker; β-catenin/c-Myc signaling pathway.

Figure 1

SNRPB2 upregulation in ESCA and its potential as a prognostic biomarker. (A) SNRPB2 expression analyzed by TCGA and GETx datasets. *p < 0.05, **p < 0.01, ***p < 0.001, ns, no significant differences. (B) The expression level of SNRPB2 in ESCA tissues was upregulated compared with that of normal tissues in the TCGA database. (C) The expression level of SNRPB2 in ESCA tissues was upregulated compared with that of paired samples in the TCGA database. (D) The expression level of SNRPB2 was associated with clinical pathological staging. (E) Validation of SNRPB2 expression in ESCA tissues using the GEO database. (F) The prognostic significance of SNRPB2 mRNA in ESCA was explored by Kaplan–Meier analyses in TCGA and GSE53625 cohorts. (G) Representative SNRPB2 IHC staining in adjacent tissues and ESCA tissues. Comparison of IHC staining intensity between adjacent tissues and ESCA tissues. Comparison of staining intensity of SNRPB2 in different tumor stages. *P < 0.05, **P < 0.01. Scale bar:20µm.

Figure 2

Knockdown of SNRPB2 suppressed the growth of ESCA cells. (A) Silencing efficiency of SNRPB2 in Eca109 and Kyse150 cells by qPCR. (B) Silencing efficiency of SNRPB2 in Eca109 and Kyse150 cells by Western blot. (C–E) CCK-8, EDU and colony formation assays showing the proliferation ability of Eca109 and Kyse150 cells. (F,G) Flow cytometry results showing the effect of SNRPB2 knockdown on apoptosis and cell cycle progression in Eca109 and Kyse150 cells. *P < 0.05, **P < 0.01, ***P < 0.001.

Figure 3

Knockdown of SNRPB2 suppressed the Migration and invasion through EMT. (A) Wound-healing assay to assess cell migration ability. (B) Transwell invasion assay to measure the cell invasion ability. (C) Western blot results showed changes in EMT. *P < 0.05, **P < 0.01. Scale bar:100 µm.

Figure 4

Overexpression of SNRPB2 promoted the growth of ESCA cells. (A, B) The efficiency of SNRPB2 overexpression was confirmed in Eca109 and Kyse150 cells through qPCR and Western blot. (C–E) Proliferation ability of Eca109 and Kyse150 cells upon SNRPB2 overexpression assessed by CCK-8, EDU, and colony formation assays. (F, G) Flow cytometry results showing the effect of SNRPB2 overexpression on apoptosis and cell cycle progression in Eca109 and Kyse150 cells. *P < 0.05, **P < 0.01.

Figure 5

Overexpression of SNRPB2 enhanced Migration and invasion through EMT. (A) Wound-healing assay to assess cell migration ability. (B) Transwell invasion assay to measure the cell invasion ability. (C) Western blot results showed changes in EMT. **P < 0.01, ***P < 0.001. Scale bar:100 µm.

Figure 6

SNRPB2 knockdown inhibits ESCA cells growth in vivo. (A, B) Images depicting tumors formed in BALB/c nude mice following subcutaneous injection of SNRPB2-knockdown Eca109 cells. (C) The tumor volumes were measured after tumor resection. (D) The tumor weights were measured after tumor resection. (E) HE staining and immunohistochemical (IHC) staining of SNRPB2 and Ki-67 antibodies were performed on sections of subcutaneous tumors. (F) Expression analysis of SNRPB2 and Ki-67 across diverse tissue sections. **P < 0.01. Scale bar:20 µm.

Figure 7

SNRPB2 regulates β-catenin/c-Myc signaling pathway in ESCA. (A) Heatmap showing the top 50 genes coexpressed with SNRPB2 in ESCA. (B) KEGG pathway enrichment analyses of SNRPB2 correlated genes in ESCA. (C, D) GSEA enrichment analysis results of SNRPB2-related genes in ESCA. (E) The expression levels of genes related to the β-catenin/c-Myc signaling pathway were determined by western blotting. (F) Quantitative analysis of the changes in SNRPB2 protein levels. **P < 0.01, ***P < 0.001.

Figure 8

Stabilizing β-catenin restored the suppression of growth, Migration, invasion caused by SNRPB2 downregulation. (A) Colony formation assays showing the proliferation ability of Eca109 and Kyse150 cells infected with Sh-NC, Sh-2, and Sh-3 after 24 h treatment with SKL2001 (20 µmol/L). (B) Wound healing assays assessing the migration ability of Eca109 and Kyse150 cells under the same treatment conditions. (C) Transwell invasion assays demonstrating the invasive potential of Eca109 and Kyse150 cells. (D) Western blot analysis of β-catenin, c-Myc protein expression in treated cells. *P < 0.05; **P < 0.01.

Figure 9

Inhibition of β-catenin reversed the growth, Migration and invasion promoted by SNRPB2 upregulation. (A) Colony formation assays showing the proliferation ability of Eca109 and Kyse150 cells infected with Vector, OE after 24h treatment with XAV-939 (20 µmol/L). (B) Wound healing assays assessing the migration ability of Eca109 and Kyse150 cells under the same treatment conditions. (C) Transwell invasion assays demonstrating the invasive potential of Eca109 and Kyse150 cells. (D) Western blot analysis of β-catenin, c-Myc protein expression in treated cells. *P < 0.05; **P < 0.01.