Restoration by polyethylene glycol of characteristics of intestinal differentiation in subpopulations of the human colonic adenocarcinoma cell line HT29.

The human colonic cancer cell line HT29 is morphologically undifferentiated in standard culture conditions. The cells were incubated for 30 s in polyethylene glycol (27%, v/v), then washed, and refed with standard medium. In these conditions of treatment, polyethylene glycol was unable to induce a significant cell multinucleation. Three wk after the treatment, circular "flat-foci" developed in the culture, which consisted of circular monolayers of polarized cells. These subpopulations were isolated, then grown as independent lines (lines 27, 28, 30, and 31) in standard culture conditions, and characterized. Two types of differentiated cells were present in these lines, namely, enterocytic cells and mucus-secreting goblet cells. These characteristics of intestinal differentiation were found to be stable during the long-term culture of these lines in standard medium. We were able to isolate from line 27 a clonal derivative (C1.27H) exhibiting 2 lineages of differentiation, as assessed by electron microscopy, immunofluorescence, and immunoblot analysis of cell membranes with anti-sucrase-isomaltase antibodies, and enzyme activities. Sucrase-isomaltase was present in two forms, namely, the high-molecular-weight precursor and the cleaved subunits. Finally, the C1.27H cells were found to be significantly less tumorigenic than the parental HT29 cells in both in vitro and in vivo tumorigenicity tests. This stably differentiated cell clone could represent the cancer derivative of the normal stem cells of the intestinal crypt. It is therefore a possible model system for the study of intestinal cell differentiation.