EFFECT OF DIBUTYRYL CYCLIC ADENOSINE-3', 5'-MONOPHOSPHATE ON MORPHOLOGICAL FEATURES AND BIOLOGICAL MARKERS OF HUMAN SALIVARY MYOEPITHELIAL CELL-LINE IN CULTURE

We have found the emergence of myoepithelial cells (HSG-AZA1) in neopl astic human salivary intercalated duct cell line HSG in culture after treatment with 5-azacytidine. When HSG-ZAZ1 cells were cultured in the presence of N6,O2-dibutyryl cyclic adenosine 3',5'-monophosphate (dB- cAMP), they formed long cytoplasmic processes which were densely packe d with ample microfibrils in addition to microtubule bundles. The expr ession of neuron-specific enolase, synaptophysin, and catecholamine as well as neurofilaments in the treated HSG-AZA1 cells was found by the immunofluorescence staining technique, immunoblotting, immunoelectron microscopy, or catecholamine fluorescence. Both the anchorage-indepen dent and anchorage-dependent growths of HSG-AZA1 cells were suppressed in the presence of dB-cAMP. After the removal of dB-cAMP from the cul ture, the treated cells returned rapidly to the phenotype and growth r ate of the untreated cells. These findings indicate that reversible di fferentiation into the neuron-like cells of HSG-AZA1 cells occurs in g rowth medium containing dB-cAMP.