Gq. Ding et al., INHIBITION OF CELLULAR GROWTH AND STEROID 11-BETA-HYDROXYLATION IN RAS-TRANSFORMED ADRENOCORTICAL-CELLS BY THE FUNGAL TOXINS BETICOLINS, Cell biology international, 20(8), 1996, pp. 523-530
The proliferation of GM16 and 4CDT ins-transformed newborn rat adrenoc
ortical (RTAC) cells and Y1 mouse adrenal tumor cells was inhibited by
beticolins, the fungal toxins extracted from Cercospora beticola, at
submicromolar concentrations in a dose-dependent manner. Inhibitory co
ncentrations for half the maximum inhibition were 150, 75 and 25 nM fo
r beticolin-1 and 230, 150 and 50 nM for beticolin-2 in GM16, 4CDT and
Y1 cells respectively. Beticolins strongly inhibited the production o
f 11 beta-hydroxysteroids on the second and third days of treatment il
l a dose-dependent manner between 0.1 and 1 mu M. Beticolins were show
n by confocal microscopy to be localized in cytoplasmic organelles abo
ut 30-40 min after treatment. This finding favors a direct action of b
eticolins on mitochondrial steroid 11 beta-hydroxylase albeit another
less direct mechanism involving a cytoplasmic signaling pathway cannot
be excluded. (C) 1996 Academic Press Limited