Decreased sensitivity of cytostatic drugs in glucocorticoid receptor-free acute myeloid leukaemia cells. Clinical and experimental observations.

Preliminary clinical observations have suggested that low cellular glucocorticoid receptor (GR) levels might have been connected with multidrug resistance in children with acute myeloblastic leukaemia (AML). To test this possibility, we have developed glucocorticoid resistant subclones of two recently established human myeloid leukaemic cell lines. The cause of glucocorticoid resistance was GR negativity in these subclones. GR positive parent cell lines or GR negative subclones were incubated for 1 h in the presence of Adriamycin, Cytosine-arabinosid, Etoposide or Vincristine, respectively. After short-term (1 h) incubation in suspension cultures cells were washed and plated in clonogenic agar cultures. Each anticancer drug was more potent against both GR positive parent cell lines than against the GR negative subclones. The results of this study suggest that the absence of GRs is a useful marker of multidrug resistance in childhood AML.