MODULATION OF P62C-MYC EXPRESSION IN A SINGLE-CASE OF NON-T ACUTE LYMPHOBLASTIC-LEUKEMIA (ALL) ASSESSED BY IMAGE ANALYZER

The effect of DMSO and PMA, compounds which mimic naturally occurring activation of protein kinase C on the p62c-myc and p75c-myb oncoprotei n expression, and the rate of DNA synthesis in ALL lymphocytes was exa mined. The level of c-myc and c-myb protein expression was assessed by computer assisted image analysis based on the intensity of staining i n cells used in immunocytochemical studies. Already after two hours of incubation, DMSO at a dilution of 0.3 % strongly down-regulated the h igh p62c-myc expression in ALL lymphocytes, while 24 hr later, the rat e of spontaneous DNA synthesis was significantly inhibited with DMSO a t a dilution of 0.6 % or more. This observation may suggest different sensitivity of c-myc protein expression and DNA synthesis to DMSO acti on. Similar effect was obtained when PMA was used. However, the percen tage of c-myb positive cells which was negligable (1 %) in freshly iso lated lymphocytes did not change in the presence of DMSO or PMA at all , indicating low differentiation capacity of these cells. Furthermore, our data indicate that computer-assisted image analysis can successfu lly distinguish variability of nuclear oncoprotein expression in immun ocytochemical preparations.