Gene-Regulated Expression of Glycolipids: Appearance of GD3 Ganglioside in Rat Cells on Transfection with Transforming Gene E1 of Human Adenovirus Type 12 DNA and Its Transcriptional Subunits1

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Abstract
Malignant transformation is known to be associated with characteristic changes of cell surface glycolipids, but the genetic background and underlying molecular mechanism of these changes are still unknown. Incorporation of oncogenic elements into cultured cells should provide a useful model for studies on this problem. We analyzed gangliosides of a clonal and fibroblastic rat cell line, 3Y1, and its transformed counterparts, E1Y, HY1, and CY1 cell lines. E1Y cells were established by transfection of 3Y1 cells with the transforming gene E1, minimum DNA fragment of human adenovirus type 12 (Ad 12) required for complete transformation of cells. HY1 cell line is the cells established with E1A which is a transcriptional subunit of the E1 and can transform incompletely cells. CY1 was established by co-transfection with parts of non-transforming gene E3 and E4 of Ad 12 DNA in addition to the E1. GD3 ganglioside (NeuAcα2–8NeuAcα2–3Galβ1–4Glcβ1–4Glcβ1–1Cer) appeared in all these transfection-transformed cells but was undetectable in untransformed control cells. The appearance of GD3 was undoubtedly due to expression of E1A gene in association with oncogenic cell transformation. The expression of other gangliosides, particularly GM2 and GM1, were also influenced by transfection, but their expressions depended on the kind of oncogenic DNA fragments used. These results all suggest that ganglioside metabolism is under unexpectedly complicated gene control.