SPECIFIC BINDING OF [PHORBOL-H-3 DIBUTYRATE TO PHORBOL DIESTER-RESPONSIVE AND DIESTER-RESISTANT CLONES OF A HUMAN MYELOID-LEUKEMIA (KG-1) LINE-1

  • 1 January 1983
    • journal article
    • research article
    • Vol. 43  (8) , 3563-3566
Abstract
Phorbol diesters induce macrophage-like differentiation in KG-1 and HL-60 human acute myelogenous leukemia cell lines. A cloned subline of KG-1, known as KG-1a, was developed that does not differentiate when exposed to phorbol diesters. Both KG-1 and KG-1a cells have a single class of specific high-affinity receptors for labeled phorbol-12,13-dibutyrate with a mean Kd of 1.47 .+-. 0.10 (SE) .times. 10-8 M and 0.85 .+-. 0.20 .times. 10-8 M for the sensitive parental KG-1 line and the resistant KG-1a subline, respectively (P < 0.025). The number of [3H]phorbol-12,13-dibutyrate binding sites (mean .+-. SE) per cell was 3.85 .+-. 0.98 .times. 105 and 3.94 .+-. 0.31 .times. 105 on KG-1 and resistant KG-1a cells, respectively. No significant decrease of specific binding with time (down regulation) was observed in either KG-1, KG-1a, or HL-60 cells, suggesting that down regulation of specific phorbol-12,13-dibutyrate binding is not critical to induction of differentiation. The presence of specific high-affinity phorbol receptors on leukemic cells does not assure that phorbol diesters can trigger their differentiation.

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