Angiogenesis and neuroblastomas: Interleukin-8 and interleukin-8 receptor expression in human neuroblastoma

Purpose: Studies have demonstrated that the pro-angiogenic cytokine interle ukin-8 (IL-8) and the IL-8 receptors likely have a role in the growth and m etastasis of various solid tumors. We hypothesized that in vivo neuroblasto ma expresses IL-8 and the IL-8 receptors A and B, and that factors known to regulate IL-8 expression are present and active in the neuroblastoma micro environment. Materials and Methods: To confirm the presence of IL-8/IL-8 receptors in ne uroblastoma, immunohistochemical analysis for IL-8 and its receptors was pe rformed on 10 archival specimens, including benign adrenal and well to poor ly differentiated neuroblastoma samples. Immunohistochemical analysis was a lso performed for interleukin-1 beta (IL-1 beta) and tumor necrosis factor- alpha. Cultured neuroblastoma cells SK-N-MC and SK-N-SH were stimulated wit h 10 ng./ml. IL-1 beta or tumor necrosis factor-alpha and control media (15 each). Cell culture supernatants were analyzed with enzyme-linked immunoso rbant assay for IL-8 levels at 24 and 48 hours. Results: Minimal expression of IL-8 was noted in benign adrenal tissue but expression for IL-8 was present in all neuroblastoma specimens. Microvessel staining was present in 30% of the specimens. All tumor specimens expresse d IL-8 receptor B, and both receptors were expressed in the tumor microvasc ulature. Immunohistochemical analysis confirmed the presence of IL-1 beta a nd tumor necrosis factor in the neuroblastoma microenvironment. In vitro st udies demonstrated that SK-N-MC and SK-N-SH cells express low levels of IL- 8 under normal conditions and that IL-1 beta and tumor necrosis factor-a si gnificantly increased expression of IL-8 at 24 and 48 hours. Conclusions: Our results indicate that IL-8 and its receptors are expressed in neuroblastoma tumor specimens. In addition, the fact that IL-1 beta and tumor necrosis factor-ct are expressed in the neuroblastoma microenvironme nt combined with our in vitro results suggests that these cytokines may be involved in in vivo regulation of IL-8 in human neuroblastoma. Understandin g the angiogenic factors and regulatory cascade promoting angiogensis in ne uroblastoma may lead to the development of effective anti-angiogenic strate gies.