Unique expression of integrin fibronectin receptors in human neuroblastoma cell lines

Cultured human neuroblastoma cells can be classified morphologically into 3 types: neuroblastic (N), intermediate (I) and substrate adherent (S). Neuroblastoma cells of all types were found to attach and display distinct morphological characteristics on fibronectin, with S‐type cells attaching better than N‐type cells. Studies of the expression of integrin fibronectin receptors (α3βI, α4β I, α5β I and αVβ I) were carried out using a total of 26 morphologically distinct cell lines and their subpopu‐lations. Fluorescence‐activated cell sorting (FACS) analysis and immunoprecipitation revealed that all S‐type cells expressed abundant α5β I, while N‐type cells barely expressed this molecule. Although α3β I expression of S‐type cells was also higher than that of N‐type cells, some N‐type cells had significantly increased levels of this molecule. α4β I was found to be randomly expressed. All cell lines tested expressed αVβ I. Human neuroblastoma cells, the majority of which are N‐type cells with very low α5β I expression, are also contrasted with other childhood cancer cells (rhabdomyosarcoma, Ewing's sarcoma, and glioma), all of which expressed high levels of α5β I. The characteristic expression of integrin fibronectin receptors may account for the clinically unique tumor behavior, and the immunohistochemical staining for integrins may become a useful alternative to conventional histology in differential diagnosis and a marker for prognosis in neuroblastoma.