DIFFERENTIATION OF Y79 RETINOBLASTOMA CELLS WITH PIGMENT EPITHELIAL-DERIVED FACTOR AND INTERPHOTORECEPTOR MATRIX WASH - EFFECTS ON TUMORIGENICITY

We investigated the in vivo differentiation potential of Y79 human ret inoblastoma cells following pre-treatment with two novel neurotrophic agents: PEDF (human recombinant pigmented-epithelial derived factor) o r IPM (interphotoreceptor matrix) wash. These agents were able to indu ce a significant degree of morphological differentiation in vitro. How ever, 48 days after subretinal transplantation of pre-treated cells, m assive tumor formation was apparent. In contrast, Y79 cells pre-treate d with retinoic acid/sodium butyrate, which attain a lesser degree of morphological differentiation, did not produce tumors over a 30 to 60 day-survival time (del Cerro et al., Brain Research, 12-22, 1992). We conclude that for PEDF and IPM, the degree of in vitro differentiation and the degree of mitotic arrest are independent features.