Closing the Phenotypic Gap between Transformed Neuronal Cell Lines in Culture and Untransformed Neurons

Abstract

Studies of neuronal dysfunction in the CNS are often limited by difficulties encountered when propagating primary neurons in vitro. Transformed neuronal cell lines can be substituted for primary cells but they often misrepresent normal conditions. We hypothesized that a 3-dimensional (3D) culture system would drive the phenotype of transformed neurons closer to that of untransformed cells, as has been demonstrated in non-neuronal cell lines. In our studies comparing 3D versus monolayer (ML) culture, neuronal SH-SY5Y cells underwent distinct morphological changes as revealed by scanning electron and confocal microscopy. Expression of the proto-oncogene N-myc and its RNA binding protein HuD was decreased in 3D culture as compared to standard ML conditions. There was a decline in the anti-apoptotic protein Bcl-2 in 3D culture, coupled with increased expression of the pro-apoptotic proteins BAX and BID. Using microarray analysis we demonstrated significantly differing mRNA levels for an additional 40 genes in the cells of each culture type. Moreover, thapsigargin-induced apoptosis was notably enhanced in the 3D cultured SH-SY5Y cells. Comprehensively, these results indicate that a 3D culture approach may begin to close the phenotypic gap between transformed neuronal cell lines and untransformed neurons and that it may readily be used for in vitro research of neuronal pathogenesis in the CNS.