Neuroblastoma impairs chemokine-mediated dendritic cell migration in vitro

Abstract

Background/purpose: Chemokine receptor (CCR7 [cysteine chemokine receptor 7]) and ligand (CCL19) interactions trigger dendritic cell (DC) recruitment from sites of antigen uptake to secondary lymphoid organs for T-cell priming and tumor lysis. Inhibition of this interaction may allow some aggressive tumors to evade immune detection. Although we have shown dysfunctional DC migration in murine neuroblastoma (NB) in vivo, the molecular mechanisms of impairment are unknown. We hypothesize that NB-induced aberrant CCR7-CCL19 signaling impairs DC migration.

Methods: Bone marrow-derived DCs were isolated from A/J mice (n = 24), matured, and cocultured with murine NB (TBJ) or media (control) for 7 days. CCR7 and CCL19 protein and RNA expressions by control and NB-exposed DC were measured by flow cytometry, Western blot analysis, and polymerase chain reaction. Migration assays using Transwell plates (Corning Incorporated, Corning, NY, via Fisher Scientific, Pittsburgh, Pa) were performed with matured DC and CCL19. Furthermore, to determine if these changes in DC migration could be overcome, superphysiological concentrations of CCL19 (100 ng/mL) were used. Results are reported as the average percentage +/- SD.

Results: No significant differences in CCR7 or CCL19 protein expression between tumor and control were seen at 7 days. However, NB significantly decreased CCL19-induced migration by more than 50%: control (26.48% +/- 1.52%) vs DC cocultured with TBJ (12.7% +/- 0.3%) (P < .05). Superphysiological doses up to 100 ng/mL CCL19 showed no significant upregulation in migration in DC cocultured with tumor cells.

Conclusions: Although in vitro coculture with NB does not induce significant changes in either CCR7 or CCL19 expression, profound functional impairments in CCR7/CCL19-mediated migration occurs. These findings suggest that intracellular signal transduction pathways for these chemokines may be impaired by tumor. Targeting this chemokine-receptor pathway may provide a novel therapeutic strategy.