Expression of Fas (APO-1/CD95) and Fas ligand (FasL) in human neuroblastoma

Background and Procedure. To determine the possible role of Fas/FasL system in the particularly heterogeneous behaviour of neuroblastoma d(NB), we hav e measured the functional expression of Fas and its ligand, FasL, in primar y neuroblastoma samples and cell lines by immunohistochemistry and flow cyt ometry. Results. Our results reveal that while Fas expression is associated with low stage and more mature tumors, heterogeneous FasL expression was m ostly detected in high stage tumors, with-our apparent correlation to MYCN amplification. Flow cytometric analysis of cell lines demonstrated a high e xpression of Fas in epithelial-type, HLA class I positive cell lines, which was lost upon activation with phorbol esters. In contrast, Fas ligand was detected in only a small subset of cell lines. Conclusions. In some cell li nes, cytotoxic assays revealed the ability of NB-associated Fas receptor to transduce an apoptotic signal upon triggering. The pattern of functional F as/FasL expression in tumours and cell lines suggests that this system may be involved in the evasion of highly malignant neuroblastoma cells to host immune response. Med. Pediatr. Oncol. 36:111-114, 2001. (C) 2001 Wiley-Liss , Inc.