Dense GM-CSFR-expressing immune infiltration is allied with longer survival of intrahepatic cholangiocarcinoma patients.

BACKGROUND

Intrahepatic cholangiocarcinoma (iCCA) is a cancer arising from intrahepatic bile duct epithelium. An iCCA incidence is increasing worldwide; however, the outcome of the disease is dismal. The linkage between chronic inflammation and iCCA progression is well established, but the roles of granulocyte-macrophage colony-stimulating factor (GM-CSF) remain unrevealed. Thus, a better understanding of GM-CSF functions in CCA may provide an alternative approach to CCA treatment.

METHODS

Differential and mRNA expressions in CCA tissues were investigated by Gene Expression Profiling Interactive Analysis (GEPIA) based on The Cancer Genome Atlas (TCGA) database. The protein expressions and localizations of GM-CSF and its cognate receptor (GM-CSFR) in iCCA patients' tissues were demonstrated by the immunohistochemistry (IHC) techniques. The survival analyses were performed using Kaplan-Meier survival analysis with log-rank test and Cox proportional hazard regression model for multivariate analysis. The GM-CSF productions and GM-CSFR expressions on CCA cells were assessed by ELISA and flow cytometry. The effects of GM-CSF on CCA cell proliferation and migration were evaluated after recombinant human GM-CSF treatment. The relationship between or level and related immune cell infiltration was analyzed using the Tumor Immune Estimation Resource (TIMER).

RESULTS

GEPIA analysis indicated and expressions were higher in CCA tissues than in normal counterparts, and high was related to the longer disease-free survival of the patients ( < 0.001). IHC analysis revealed that CCA cells differentially expressed GM-CSF, while GM-CSFR was expressed on cancer-infiltrating immune cells. The patient whose CCA tissue contained high GM-CSF expressed CCA, and moderate to dense GM-CSFR-expressing immune cell infiltration (ICI) acquired longer overall survival (OS) ( = 0.047), whereas light GM-CSFR-expressing ICI contributed to an increased hazard ratio (HR) to 1.882 (95% CI [1.077-3.287]; = 0.026). In non-papillary subtype, an aggressive CCA subtype, patients with light GM-CSFR-expressing ICI had shorter median OS (181 . 351 days; = 0.002) and the HR was elevated to 2.788 (95% CI [1.299-5.985]; = 0.009). Additionally, TIMER analysis demonstrated expression was positively correlated with neutrophil, dendritic cell, and CD8+ T cell infiltrations, though it was conversely related to M2-macrophage and myeloid-derived suppressor cell infiltration. However, the direct effects of GM-CSF on CCA cell proliferation and migration were not observed in the current study.

CONCLUSIONS

Light GM-CSFRα-expressing ICI was an independent poor prognostic factor for iCCA patients. Anti-cancer functions of GM-CSFR-expressing ICI were suggested. Altogether, the benefits of acquired GM-CSFR-expressing ICI and GM-CSF for CCA treatment are proposed herein and require elucidation.