Fna. Sackey et al., CELL-CYCLE REGULATION OF MEMBRANE GLUCOCORTICOID RECEPTOR IN CCRF-CEMHUMAN ALL CELLS - CORRELATION TO APOPTOSIS, American journal of physiology: endocrinology and metabolism, 36(3), 1997, pp. 571-583
The human leukemic cell line (CCRF-CEM) and a subline enriched for the
plasma membrane-resident glucocorticoid receptor (mGR) were studied f
or the influence of the cell cycle on the expression and function of m
GR. Three synchronization procedures (double thymidine, colcemid, and
combined thymidine-colcemid blocks) were used. Fluorescent microscopy
and flow cytometry simultaneously assessed antibody-tagged mGR and DNA
. In addition, mGR was quantitated and characterized by immunoprecipit
ation and immuno-blotting. Apoptosis was assayed by DNA fragmentation
(TUNEL assay) and by cell survival (trypan blue exclusion). All synchr
onization procedures demonstrated that progression from DNA replicatio
n (S) to the second growth phase and mitosis (G(2)/M) leads to cells h
aving the highest levels of mGR expression and being highly glucocorti
coid sensitive in the apoptosis assays: 32 and 80% sensitivity of wild
type and mGR-enriched cells, respectively, compared with 12 and 30% s
ensitivity in asynchronous cells. Therefore, mGR expression appears to
be cell cycle regulated, with its highest expression at late S-G(2)/M
, when the cells are most sensitive to the lymphocytolytic effects of
glucocorticoids.