Ultrastructural differentiation of sodium butyrate-treated human pancreatic adenocarcinoma cell lines.

The differentiation effects of sodium butyrate were examined in a series of human pancreatic adenocarcinoma cell lines: Panc-1, a poorly differentiated cell line; HPAF, a pleomorphic cell line isolated in this laboratory; and two clones of the parental HPAF cell line, well-differentiated CD11 and less-differentiated CD18. Incubation with 2 mM sodium butyrate induced a dramatic decrease in cell proliferation and saturation densities in culture and an increase in alkaline phosphatase activity. Of particular interest, incubation with sodium butyrate also caused a number of morphologic alterations in these cells, attributed to an induction of secretory differentiation. Following sodium butyrate treatment, CD18 cells were virtually indistinguishable from the more highly differentiated CD11 cells as evidenced by an increase in the number of profiles of rough endoplasmic reticulum and of Golgi. Intercellular and intracytoplasmic lumens, whose appearance is quite common in CD11 cells but nonexistent in untreated CD18 cells, appeared in these cells following only 5 days of sodium butyrate treatment. An increase in the cytoplasmic secretory elements was also observed in sodium butyrate-treated Panc-1 cells; however, lumen formation never occurred in these cells.