PCC3 mouse
teratocarcinoma (TCC) stem cells were cotransfected with either the plasmid p delta C-1A or p delta C-1B carrying the chicken
delta-crystallin gene, and with the plasmid pSV2gpt containing the selectable bacterial
xanthine-guanine phosphoribosyltransferase (XGPRT) gene, using the
calcium phosphate technique. Nine transformed PCC3 stem cell lines, each of which was clonally derived from respective colonies surviving after the selection process, were isolated. Southern blot analysis revealed that all of them stably maintained
delta-crystallin sequences associated with high mol. wt. cellular
DNA after propagation in non-selective medium in vitro, and after the production of solid
tumors in the syngenic host mice. Six cell lines contain the intact
delta-crystallin gene sequence and eight contain the gpt sequence. The number of
delta-crystallin DNA copies was highly variable among transformed lines, 1-500
delta-crystallin genes per diploid mouse genome. No expression of the exogenous genes was detected in the transformed cells as long as they were in the undifferentiated state. However, the synthesis of
delta-crystallin in certain types of cells was detected immunohistologically in three lines after the differentiation. The positive cell types were unique to each line, skeletal muscle in Y delta-9, certain columnar epithelia in Y delta-2, and unidentified spindle-shaped cells in Y delta-3. Authentic
delta-crystallin polypeptides with a mol. wt. of 48 000 are synthesized upon differentiation of line Y delta-3 in solid
tumors in syngenic mice.