DifferentialEffects of SodiumButyrate,DimethylSulfoxide,and RetinoicAcid on Membrane-associatedAntigen, Enzymes,and Glycoproteinsof HumanRectalAdenocarcinomaCells1

and purine analogs (37), antimetabolites (42) and vitamin A (27, 38). Different inducers of differentiation may not act by the same mechanisms and may induce different phenotypic expression (14, 35, 17). For example, variant clones of murine erythroleukemic cells which are resistant to one inducer may differentiate in the presence of another inducer. The ratio of @6 minor globin chains in these cells may vary depending on inducer (35). We have reported previously that sodium butyrate and DM503 had considerable effects on the biochemical properties of poarly differentiated human colon cancer cells and that these effects were reversible (20). The studies of the effects of 3 putative differentiating agents (sodium butyrate, DMSO, and retinoic acid) on human colonic cancer cells have been ex tended to several other tumor cell lines. In the present study, the effects of the 3 differentiating agents on cellular morphol agy, growth rate, cell surface glycoproteins, and several mem brane-associated enzymes are compared using a human rectal carcinoma cell line, HAT-i 8, which is poorly differentiated.