CONTRIBUTION OF APOPTOSIS TO THE PHENOTYPIC CHANGES OF ADRENOCORTICAL-CELLS IN PRIMARY CULTURE

The aim of this study was to evaluate the occurrence and physiological consequences of apoptosis in primary cultures of bovine adrenocortica l cells (of fasciculata-reticularis origin). Under ACTH-free culture c onditions, we observed apoptotic cells in the cell layer and the accum ulation of apoptotic bodies in the culture medium. These were hardly d etectable in ACTH-supplemented cultures. Under ACTH-free conditions, t he DNA content of apoptotic bodies collected over 48 h represented up to 10-15% of that of the cell layer at the onset of the culture (as co mpared to 3% in ACTH-supplemented cultures). Past the fourth day of cu lture in the absence of ACTH, most cells lacked several markers of the ir originating fasciculata-reticularis phenotype and progressively evo lved to an undifferentiated phenotype. The vast majority of the apopto tic bodies released during the first 4 days of culture were immunoreac tive for P450(17 alpha). Inversely, during the same period of time, th e proliferating cells (PCNA-positive) did not appear to express P450(1 7 alpha). Therefore, apoptosis could contribute, together with dediffe rentiation, to the phenotype shift observed in ACTH-depleted cultures of adrenal fasciculata-reticularis cells. These observations also char acterize this endocrine cell system as an in vitro model for the study of hormone-repressed apoptosis.