Establishment of rat endometrial cell lines by retroviral mediated transfer of immortalizing and transforming oncogenes.

To study hormone responsive genes in differentiated epithelial cells and as a model for endometrial carcinoma, lines were established from primary rat endometrial cells by infection with replication-defective retroviruses carrying oncogenes and the selectable gene neo. The initial step involved immortalization through the large T antigen of SV40 to generate a line we designate RENT4, or with the E1a gene of adenovirus to generate lines referred to as RENE1 and RENE2. Additionally, lines generated by large T antigen of SV40 were superinfected with a replication-defective retrovirus harboring the v-Ha-ras oncogene and selected by the ability to form colonies in soft agar. The latter cell lines appeared fully transformed and were designated RENTR01 and RENTR03. Five established lines were characterized for steroid hormone receptors, alkaline phosphatase activity and their complement of the intermediate filaments vimentin and cytokeratin. With the exception of the RENE1 cells all other lines have normal levels of glucocorticoid receptor, whereas only RENE1, RENE2 and RENT4 were positive for the progesterone receptor. RENTR01, RENTR03 and, to a lesser extent, RENE1 exhibited differential expression of cytokeratins dependent upon whether the cells were grown on a substrata of NIH3T3 cells. When grown on formalin-fixed NIH3T3 cells, RENTR01 and RENTR03 cells appeared to differentiate or rearrange themselves in culture. Individual islands of cells showed a heterogeneous pattern of intermediate filaments with vimentin-positive cells localized to the outer portion of the islands whereas cytokeratin-positive cells are seen on the insides of these structures.