Elevation of a potassium current in differentiating human leukemic (HL‐60) cells

Abstract

Human promyelocytic leukemia (HL-60) cells display a novel voltage-dependent outward current under voltage clamp. This current is present at low levels in the proliferative state and in granulocytes derived from HL-60 cells which were induced to differentiate with retinoic acid. It is elevated in macrophages derived from HL-60 cells after exposure to phorbol-12-myristate-13-acetate (PMA). The current is carried primarily by K+, is blocked by Cs+ and by increased intracellular concentrations of Cl-. From a holding potential of -80 mV, significant activation required depolarization to +20 mV membrane potential. Activation was not influenced by intracellular Ca2+ (1-2 X 10(-6) M). These properties appear to differ significantly from the Ca2+-activated K+ channel and the delayed rectifier. The increase of this voltage-activated current in differentiation toward the macrophage, but not the granulocyte, suggests that this current is correlated specifically with macrophage differentiation.

Human neuroblastoma cell lines as models for the in vitro study of neoplastic and neuronal cell differentiation.

“…Morgan and Curran (50) described induction of the oncogene c-fos in the pheochromocytoma cell line PC12 with agents that affect voltage-dependent Ca channels. In the leukemic cell line HL-60, and in murine erythroleukemia cells (MEL), alterations in Na-H exchange, increases in voltageactivated K current, and changes in intracellular Ca concentrations have been observed accompanying chemically induced cell maturation (51)(52)(53)(54)(55). In murine NB cell lines, the K ionophore valinomycin (55) and high levels of extracellular Ca (56) have been shown to cause neurite extension.…”

A review of select minerals influencing the haematopoietic process

“…The differentiation of some leukaemic myeloid lineage cells is also correlated with K channels. Promyelocytic HL-60 cells present a slow-inactivated K channel ( 96 ) , and promonocytic U-937 cells exhibit abnormal conductance in K channels ( 97 ) . On the other hand, in myeloid ML-1 cells, K current is suppressed during cell differentiation ( 98 ) .…”

Mode of Action of Membrane Perturbing Agents: Snake Venom Cardiotoxins and Phospholipases A

“…Cells were voltage-clamped at room temperature (21-23oC) using the wholecell variant of the patch clamp method previously described (Wieland et al, 1987;.…”