Single-cell analysis reveals a LAMB3-dependent immunosuppressive environment in gallbladder neck/cystic duct...

Gallbladder cancer (GBC) originating from the fundus/body (GBC^F/B) and neck/cystic duct (GBC^N/CD) exhibits distinct clinical outcomes. Location-associated heterogeneity is intricately linked to oncogenic properties and multicellular interactions within the tumor microenvironment (TME).

Single-cell transcriptomic analysis was performed on 569,736 cells derived from 38 GBC^F/B and 17 GBC^N/CD samples. Whole-exome sequencing (WES) was used to identify genomic alterations in malignant epithelial cells. Additionally, TCGA datasets, multiplex immunohistochemistry, scTCR-seq, spatial transcriptomics, and functional assays were integrated to investigate subtype-specific differences.

The cellular atlas revealed distinct TME patterns. Hallmarked by TP53 mutations and robust antigen presentation, GBC^F/B tumors were enriched with plasma cells (p = 0.009), CXCL13⁺ T cells (p = 0.046), CXCL9⁺ macrophages (p = 0.042), and proliferative immune cells (p = 0.015), constituting an immune-activated TME. Conversely, stem-like GBC^N/CD tumor cells fostered an angiogenic, immunosuppressive milieu, enriched with endothelial cells (p = 0.02), SPP1⁺ macrophages (p = 0.006), MYH11⁺ vCAFs (p = 0.029), and GZMK⁺NR4A2⁺CD8⁺ T cells (p = 0.028). Notably, elevated LAMB3 in GBC^N/CD tumor cells emerged as a central immune regulator, driving macrophage infiltration and T-cell dysfunction to establish an immunosuppressive niche.

This study underscores the profoundly immunosuppressive microenvironment in gallbladder cancer originating from the neck/cystic duct (GBC^N/CD), highlights the role of LAMB3⁺ tumor cells in immune modulation, and identifies LAMB3 as a potential therapeutic target for GBC^N/CD.

By delineating distinct TME landscapes between GBC originating from the fundus/body (GBC^F/B) and those from the neck/cystic duct (GBC^N/CD), this study provides compelling evidence for site-specific precision therapeutic strategies. We demonstrate that GBC^F/B tumors are highly enriched with established biomarkers predictive of immunotherapy responsiveness-including elevated tumor mutational burden, robust PD-L1 and interferon-γ signatures, and abundant CXCL13⁺ T cells, plasma cells, and CXCL9⁺ macrophages-indicating these patients are optimal candidates for immunotherapeutic interventions. Conversely, GBC^N/CD tumors exhibit a profoundly immunosuppressive TME orchestrated by LAMB3⁺ tumor cells. Targeting LAMB3 therefore represents a promising approach to overcome immune resistance in patients with GBC^N/CD.