Figure 4.

Elevated circulating neuropeptide Y (NPY) and high Y5 receptor (Y5R) expression are associated with neuroblastoma (NB) dissemination and an invasive phenotype. A: Serum NPY concentration are elevated in patients with metastases at diagnosis (median, 0.44 and 1.11 ng/mL for patients with localized disease and distant metastases, respectively) and future relapse (median, 0.50 and 1.34 ng/mL for patients without disease recurrence and with relapse, respectively). B: A representative image of Y5R immunostaining (brown) in differentiating human NB. C–H: Representative micrographs of Y5R immunostaining in undifferentiated human NB cells with angioinvasive characteristics. C and D: Groups of Y5R-positive NB cells or isolated tumor cells accumulate in close proximity to blood vessels and align along them. E and F: Y5R-positive cells penetrate the vessel wall. G: A Y5R-positive cell with a morphologic deformation that is characteristic of the intravasating tumor cells. H: The Y5R-positive cells are also detectable in the vessel lumen. Red arrows indicate Y5R-positive tumor cells, whereas red arrowheads indicate Y5R-positive endothelial cells. Data are presented as box plots representing range (vertical lines), 25th and 75th percentile (bottom and top of the box, respectively), and median value (solid horizontal line within the box) (A). n = 44 (A, localized disease); n = 39 (A, distant metastases); n = 55 (A, no relapse); n = 21 (A, relapse). ^∗P < 0.05, ^∗∗∗∗P < 0.0001. Scale bars: 100 μm (B); 50 μm (C–H). V, blood vessel.