Attachment culture of human retinoblastoma cells: long-term culture conditions and effects of dibutyryl cyclic AMP.

Cells from the Y-79 human retinoblastoma line were successfully grown as long-term monolayer cultures in serum-supplemented or serum-free, defined medium after pretreatment of the substrate with poly-D-lysine and fibronectin. A significant proportion of the cells differentiated morphologically in serum-free, defined medium as well as in serum-containing medium after treatment with dibutyryl cyclic AMP (dbcAMP). In the defined medium, approximately 30% of the cells showed development of long, ramifying processes, consistent with putative neuronal differentiation. Addition of dbcAMP in the defined medium resulted in an increasing number of differentiating cells (up to 50%); scattered flat cells were observed as well. Treatment of serum-supported cultures with dbcAMP resulted in a larger proportion (10%) of flat cells. Attempts to differentiate the cells with retinoic acid were unsuccessful. These results show that Y-79 cells can grow in attachment culture and differentiate into at least two distinct morphological cell types as well as offering an interesting system for studying the factors controlling growth and differentiation in human tumor cells in vitro.