Elevated glucocorticoid receptor binding in cultured human lymphoblasts following hydroxyurea treatment: lack of effect on steroid responsiveness
While studying the effects of chemotherapy on glucocorticoid receptor (GR) binding levels in hematological malignancies, we observed a sizable increase in nuclear GR binding of (/sup 3/H)dexamethasone in peripheral leukocytes from a chronic basophilic leukemia patient following treatment with hydroxyurea plus prednisone, but not after prednisone alone. This apparent clinical effect of hydroxyurea led to an examination of hydroxyurea effects on GR binding and sensitivity in the glucocorticoid-sensitive human lymphoblast cell line GM4672A. GR binding levels in GM4672A cells were measured following a 3-day exposure to 50 microM hydroxyurea, a concentration chosen to have a minimal but measurable effect on cellular growth rates with little or no effect on cellular viability. Under these conditions, nuclear (/sup 3/H)dexamethasone receptor binding measured by Scatchard analysis using a whole-cell assay was elevated 2.4-fold over control values (P less than 0.05), while cytosolic residual receptor binding (measured at 37/sup 0/C) remained unchanged. Thus, the total cellular content of measurable GR was increased, and this increase was totally accounted for by GR capable of nuclear binding. Hydroxyurea treatment of GM4672A cells had no effect on the affinity of nuclear or cytosolic GR for (/sup 3/H)dexamethasone. The increase in measurable nuclear-bound receptors occurred in a time-dependent manner over a period of 3 days and was fully reversible within 3 days following removal of hydroxyurea. The increase in receptor binding could not be explained by the slight alterations in cell cycle kinetics which occur at this low level of hydroxyurea. Despite increased receptor binding, cellular glucocorticoid responsiveness was unaltered as assessed by dexamethasone inhibition of cell growth and dexamethasone inhibition of a urokinase-like plasminogen activator.
- Research Organization:
- Yale Univ. School of Medicine, New Haven, CT
- OSTI ID:
- 5119443
- Journal Information:
- Cancer Res.; (United States), Vol. 8
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
GLUCOCORTICOIDS
RECEPTORS
HYDROXYUREA
BIOLOGICAL EFFECTS
CELL CYCLE
DEXAMETHASONE
DNA
HELA CELLS
LEUKEMIA
LYMPHOCYTES
TRITIUM COMPOUNDS
ADRENAL HORMONES
AMIDES
ANIMAL CELLS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CONNECTIVE TISSUE CELLS
CORTICOSTEROIDS
DISEASES
HEMIC DISEASES
HORMONES
HYDROXY COMPOUNDS
KETONES
LABELLED COMPOUNDS
LEUKOCYTES
MATERIALS
MEMBRANE PROTEINS
NEOPLASMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PREGNANES
PROTEINS
SOMATIC CELLS
STEROID HORMONES
STEROIDS
560301* - Chemicals Metabolism & Toxicology- Cells- (-1987)
550201 - Biochemistry- Tracer Techniques