CYCLIC AMP‐TREATED SARCOMA CELLS ACQUIRE SEVERAL MORPHOLOGICAL CHARACTERISTICS OF NORMAL FIBROBLASTS

Normal fibroblasts growing in tissue culture have elongated cell bodies, long, narrow cellular processes, and orient in, parallel arrays. Growth and cell division cease when the cell layer becomes confluent. This latter characteristic has been termed contact inhibition of growth. Tumor cells show altered characteristics. In general, they have a polygonal cell shape, few, if any, cell processes, show less tendency to orient in parallel arrays, and show little evidence for contact inhibition of growth, since extensive “piling up” of cells is frequently observed during prolonged incubations. Because all normal cells contain cyclic AMP, it seems likely that cyclic AMP may have a role in the morphologic and growth characteristics of normal cells. This function may be lost or altered during transformation. Some data reported in the literature suggest that cyclic AMP may indeed have these functions. Cyclic AMP and its derivative, Na,Oz’-dibutyryl cyclic AMP (dbcAMP) inhibit the growth of transformed cells, but not the untransformed parent.’-:{ Also, a decreased level of adenyl cyclase activity has been reported in a polyoma virus-transformed fibroblast4 We have recently found that sarcoma cells treated with cyclic AMP or its analogue, dbc-AMP, acquire some morphological and growth characteristics of normal fibroblasts.s