Effects of dibutyryl cyclic adenosine monophosphate on nucleolar organizer regions and epidermal growth factor receptor of Dunn osteosarcoma cells.

We investigated the characteristics of nucleolar organizer regions (NORs) and epidermal growth factor receptor (EGFR) on differentiated Dunn osteosarcoma in response to dibutyryl cyclic adenosine 3',5'-monophosphate (Bt2cAMP). In the presence of 3 mM Bt2cAMP, the mean number of NORs was significantly decreased in 24 hrs and 48 hrs compared with the untreated group. Also, EGFR affinity was decreased and the EGFR number was increased in response to the cellular differentiation by Bt2cAMP. The decrease in EGFR affinity might be considered as an indicator of differentiation or the mature state of the cells. Thus, the present study provides a new clue to support differentiation of osteosarcoma cells from the viewpoint of NORs findings and EGFR analysis as a differentiation marker.