Auranofin increases the affinity of phorbol dibutyrate receptors in chronic lymphocytic leukemia cells (B cells) | JoVE Visualize

Auranofin increases the affinity of phorbol dibutyrate receptors in chronic lymphocytic leukemia cells (B cells)

P D Zalewski, I J Forbes, L Valente

Journal of Immunology (Baltimore, Md. : 1950)|May 1, 1987

View abstract on PubMed

Summary

Auranofin (AF) enhances the binding of phorbol dibutyrate (PDBu) to chronic lymphocytic leukemia (CLL) B cells by increasing receptor affinity and cell membrane translocation. This effect is partially dependent on intracellular calcium levels.

Area of Science:

Immunology
Pharmacology
Cell Biology

Background:

Auranofin (AF), a lipophilic gold complex, is known to modulate leukocyte metabolism.
Phorbol esters, like phorbol dibutyrate (PDBu), bind to protein kinase C (PKC).
Previous research indicates AF affects metabolic events in leukocytes stimulated by phorbol esters.

Purpose of the Study:

To investigate the effect of auranofin (AF) on phorbol dibutyrate (PDBu) binding to human chronic lymphocytic leukemia (CLL) B cells.
To elucidate the mechanism by which AF influences PDBu receptor binding.
To determine the role of intracellular calcium in AF-mediated PDBu binding.

Main Methods:

Assessing PDBu binding to CLL B cells in the presence and absence of AF.
Measuring changes in PDBu receptor affinity (Kd) and receptor translocation.
Utilizing calcium indicators (quin-2) and antagonists (EGTA, TMB-8) to evaluate calcium dependency.

Main Results:

AF significantly enhanced PDBu binding to CLL B cells.
AF increased the affinity of PDBu receptors (Kd decreased from 20.3 nM to 7.3 nM).
AF promoted the translocation of PDBu receptors to the cell membrane.
AF-induced PDBu binding was partially reversible by calcium chelators, suggesting partial calcium dependence.
AF treatment led to a significant rise in intracellular calcium levels in CLL cells.

Conclusions:

Auranofin (AF) enhances phorbol dibutyrate (PDBu) binding to its receptor on chronic lymphocytic leukemia (CLL) B cells.
This enhancement is mediated by increased receptor affinity and translocation to the cell membrane.
The mechanism of AF action is partially dependent on intracellular calcium mobilization.
Observed effects occur at cellular concentrations relevant to chrysotherapy for rheumatoid arthritis.