Characteristics of an established cell line of retinoblastoma

The in vitro growth pattern and the morphologic, biochemical, and cytogenetic characteristics of a line of human retinoblastoma cells (Y79) maintained continuously in tissue culture for 36 months are described. This is the first “established” culture to be derived from 45 retinoblastomas which have been in tissue culture for 8 years. The established cell line grew in suspension with clusters of retinoblastoma cells which resembled, by light and electron microscopy, the cells of the original tumor. The cultured tumor cells had ultrastructural characteristics (nuclear membrane infoldings, triple membrane structures, microtubules, large coated vesicles, centrioles, basal bodies, and annulate lamellae) similar to those seen in the original tumor. Cytogenetic studies showed a hypertriploid modal line with variable numbers of minute chromosomes. Although no viral particles were found by electron microscopy, activity of an RNA-directed DNA polymerase with a template specificity like that seen in oncogenic RNA tumor viruses was demonstrated in the cultured cells.