Establishment and characterization of a new human gallbladder cancer cell line, OCUG-2.

Abstract

Background: Gallbladder cancer (GBC) is a highly aggressive malignant tumor originating from the biliary tract. As one of the most common malignancies in the biliary system, GBC is particularly challenging due to its tendency to remain asymptomatic, which often results in delayed diagnoses even at advanced stages. Combined with its invasive potential and poor response to conventional therapies, GBC has a high mortality rate, highlighting the critical need for innovative therapeutic approaches. Identifying molecular biomarkers for early detection and discovering novel therapeutic targets might be essential to improving outcomes of patients with GBC.

Aim: To establish a novel GBC cell line to investigate the molecular mechanisms underlying GBC progression and evaluate potential therapeutic targets.

Methods: We developed a unique GBC cell line, named OCUG-2, derived from a metastatic peritoneal implant, and verified its authenticity using short tandem repeat (STR) profiling. RT-PCR and RNA sequencing (RNA-seq) were performed to assess gene expression profiles, with functional enrichment analyzed through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. The MTT cell proliferation assay and an invasion assay were performed to evaluate response to nine inhibitors. Immunohistochemistry (IHC) was conducted on 34 GBC samples to analyze insulin-like growth factor 1 receptor (IGF1R) expression.

Results: OCUG-2 cells displayed adhesive growth with dendritic morphology and a 30-hour doubling time. Subcutaneous inoculation of OCUG-2 cells into mice confirmed their tumorigenic potential. STR analysis authenticated the cell line, and there was high mRNA and protein expression of IGF1R in OCUG-2 cells. The IGF1R inhibitor picropodophyllotoxin significantly inhibited OCUG-2 cell proliferation, yielding an IC₅₀ of 0.49 μM. RNA-seq analysis identified gene fusions, and GO/KEGG functional enrichment analyses revealed pathways implicated in cancer progression. IHC analysis showed IGF1R positivity in 18 of 34 GBC cases, with significant association between IGF1R expression and poor prognosis. In invasion assays, an IGF1R inhibitor effectively reduced OCUG-2 cell invasiveness.

Conclusion: IGF1R might be a promising target for GBC. The newly established OCUG-2 cell line serves as a valuable model for investigating the molecular mechanisms of GBC and evaluating therapeutic strategies.