Nucleocytoplasmic β-catenin expression contributes to neuroendocrine differentiation in muscle invasive bladder cancer

Abstract

Bladder cancers are heterogeneous in nature, showing diverse molecular profiles and histopathological characteristics, which pose challenges for diagnosis and treatment. However, understanding the molecular basis of such heterogeneity has remained elusive. This study aimed to elucidate the molecular landscape of neuroendocrine-like bladder tumors, focusing on the involvement of β-catenin localization. Analyzing the transcriptome data and benefiting from the molecular classification tool, we undertook an in-depth analysis of muscle-invasive bladder cancers to uncover the molecular characteristics of the neuroendocrine-like differentiation. The study explored the contribution of transcription factors and chromatin remodeling complexes to neuroendocrine differentiation in bladder cancer. The study revealed a significant correlation between β-catenin localization and neuroendocrine differentiation in muscle-invasive bladder tumors, highlighting the molecular complexity of neuroendocrine-like tumors. Enrichment of YY1 transcription factor, E2F family members, and Polycomb repressive complex components in β-catenin-positive tumors suggest their potential contribution to neuroendocrine phenotypes. Our findings contribute valuable insights into the molecular complexity of neuroendocrine-like bladder tumors. By identifying potential therapeutic targets and refining diagnostic strategies, this study advances our understanding of endocrinology in the context of bladder cancer. Further investigations into the functional implications of these molecular relationships are warranted to enhance our knowledge and guide future therapeutic interventions.

Keywords: Polycomb repressive complex; bladder cancer; molecular subtype; neuroendocrine differentiation; transcriptomics.

FIGURE 1

Localization of β‐catenin in muscle‐invasive bladder tumors. (A) Representative microscopy images of β‐catenin immunohistochemistry staining. (B) Nucleocytoplasmic localization of β‐catenin in patients with muscle‐invasive bladder cancer (MIBC) and small‐cell cancer of bladder (SCCB).

FIGURE 2

Neuroendocrine (NE) features of β‐catenin positive muscle‐invasive bladder cancer (MIBC) tumors. (A) β‐Catenin‐positive MIBC tumors demonstrating positive IHC staining for neuroendocrine markers, synaptophysin (SYP) and CD56. (B) Immunohistochemistry (IHC) staining scores in β‐catenin‐positive MIBC (Pos), β‐catenin negative MIBC (Neg), and small‐cell cancer of bladder (SCCB) samples (Only the IHC scores of samples subjected to RNA‐seq are displayed). (C) Molecular classification of study group samples by consensus classifier tool. (D) Distribution of NE‐like score among β‐catenin‐positive MIBC, β‐catenin‐negative MIBC, and SCCB samples.*p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001. Ba, basal; Ba/Sq, basal/squamous; LumNS, luminal nonspecified; LumP, luminal papillary; LumU, luminal unstable; ns, nonsignificant; Sq, squamous.

FIGURE 3

Characterization of mRNA signatures of β‐catenin‐positive muscle‐invasive bladder cancer (MIBC) tumors. (A) Gene set analysis of bladder cancer‐related signatures. (B) Comparison of expression genes associated with neuroendocrine differentiation in three groups. (C) Significantly enriched gene sets in β‐catenin‐positive MIBC patients (Pos). (D) Significantly enriched gene sets in β‐catenin negative MIBC patients (Neg). NES, normalized enrichment score; SCCB, small‐cell cancer of the bladder.

FIGURE 4

Identification and analysis of key modules. (A) Heatmap of the correlation between the module eigengenes (ME) and traits. (B) Top 10 enrichment results of Gene Ontology (GO)‐Biological Process, Reactome, and Wikipathway analysis by EnrichR for two significant modules (antiquewhite4 and brown2).

FIGURE 5

Dynamics in transcriptional regulation in β‐catenin‐positive muscle‐invasive bladder cancer (MIBC) tumors. (A) Transcription factor binding motif enrichment analysis of co‐expression modules brown2 and antiquewhite4. (B) mRNA expression levels of YY1 and E2F1 in the study cohort and The Cancer Genome Atlas (TGCA) bladder urothelial carcinoma (BLCA) dataset (B). Heatmap depicting expression of E2F family genes in the study cohort and the TGCA BLCA dataset (C). Ba, basal; LumNS, luminal nonspecified; LumP, luminal papillary; LumU, luminal unstable; Neg, β‐catenin‐negative MIBC; Pos, β‐catenin‐positive MIBC; SCCB, small‐cell cancer of bladder; Sq, squamous.

FIGURE 6

Association of neuroendocrine (NE) differentiation of muscle‐invasive bladder cancer (MIBC) with Polycomb repressive complex (PRC). (A, B) Expression levels of PRC components in (A) the study cohort and (B) The Cancer Genome Atlas bladder urothelial carcinoma (BLCA) dataset. (C, D) Protein–protein interaction network showing (C) PRC1 and (D) PRC2 component genes in two modules. Ba, basal; LumNS, luminal nonspecified; LumP, luminal papillary; LumU, luminal unstable; Neg, β‐catenin‐negative MIBC; Pos, β‐catenin‐positive MIBC; SCCB, small‐cell cancer of bladder; Sq, squamous.