VLA and α6β4 integrin expression in neuroendocrine carcinomas of the skin (their xenografts on nude mice and a corresponding primary culture)

Immunohistological expression of VLA1–5 and α6β4 integrins have been studied in 21 cases of primary neuroendocrine carcinomas of the skin (NECS), three xenografts on nude mice and one NECS cell culture. The phenotypic properties of NECS cells were largely maintained in NECS grafted on athymic nude-mice and in the corresponding cell line. Our results indicate that α1β1 and to a lesser extent α3β1,α5βl are the main integrins expressed in NECS. In addition, VLA2,4 and α6β4 are heteroge-neously expressed in the same group of tumors and very sparsely present. These data suggest that like neuroblastoma and primitive peripheral neuroectodermal tumor (pPNET) the absence or the heterogeneous distribution of such integrins is correlated with the aggressive behaviour of NECS although long-term follow-up was not available for our cases. On the other hand, the α1 expression could be regarded as a novel marker for differential diagnosis between NECS (α1+) and pPNET (α1−). The α1β1, α2β1, α3β1, α5βl heterodimers in the 21 NECS studied showed an uniform pericellular staining of both the peripheral cells and central cells of the tumor islands. The predominant expression of α1β1 is consistent with the hypothesis of a primitive epithelial totipotential origin in NECS.