Comparative evaluation of S9788, verapamil, and cyclosporine A in K562 human leukemia cell lines and in P-glycoprotein-expressing samples from patients with hematologic malignancies

Abstract

The activity of S9788, recently synthetized as a modulator of multidrug resistance (MDR), was compared with verapamil and cyclosporine A in normal sensitive and MDR K562 cell lines, then in samples from 33 patients with hematological malignancies, using flow cytometry with simultaneous detection of P-glycoprotein and determination of intracellular daunorubicin fluorescence. This technique was compared and correlated with a tritiated daunorubicin accumulation method. In K562 cell lines, S9788 exhibited a significantly higher reversing activity than verapamil and cyclosporine A, and allowed a complete restoration of the accumulation of daunorubicin when used at 5 mumol/L. In the clinical samples, the three compounds were evaluated at equimolar concentration (5 mumol/L) using concomitant exposure to daunorubicin and to the reversing agent. In P-glycoprotein-negative samples, no significant effect on intracellular daunorubicin fluorescence of any of the reversing agents was noted. In the 15 P- glycoprotein-positive samples, a significant increase in daunorubicin fluorescence, by at least one reversing agent, was seen in 10 cases, among which S9788 reversing activity was higher than that of the two other agents in seven cases. Complete reversal was only achieved in one case with S9788.

Influence of S9788, a new modulator of multidrug resistance, on the cellular accumulation and subcellular distribution of daunorubicin in p‐glycoprotein‐expressing MCF7 human breast adenocarcinoma cells

“…The flow cytometric procedure reported in this paper is interesting, because both parameters can be determined simultaneously; therefore, the evaluation of multidrug-resistance modulators is applicable to clinical specimens of either hematological malignancies (33) or solid tumors (3). The additional labeling by propidium iodide is useful for avoiding experimental artefacts encountered with conventional functional analyses of multidrug resistance, which cannot distinguish membrane-altered cells Daunorubicin was selected among other anthracyclines, because its fluorescence intensity did not overlap the fluorescence signal of propidium iodide in the sensitive cell line (data not shown).…”

Influence of SDZ‐PSC833 on daunorubicin intracellular accumulation in bone marrow specimens from patients with acute myeloid leukaemia

“…The techniques used are based upon the determination of PGP expression (Kuwazuru et al, 1990;Campos et al, 1992) or mdr1 gene expression (Marie et al, 1991;Pirker et al, 1992). We previously reported (Guerci et al, 1995;Merlin et al, 1994) that doublelabelling flow cytometry enables the simultaneous determination of PGP expression and its functionality through IDF. This analytical procedure was validated in demonstrating that IDF correlated with tritiated daunorubicin intracellular accumulation (Merlin et al, 1994) and was used to investigate the modulating activity of second-generation MDR modulators such as S9788 (Merlin et al, 1994(Merlin et al, , 1995a and tiapamil analogues (Abderrabi et al, 1996), as well as non-chemical modulation by liposome-encapsulated daunorubicin (Merlin et al, 1995b).…”

“…K562 human leukaemic cell line and its doxorubicin-selected subline K562-DXR were maintained in RPMI 1640 medium supplemented by 10% heatinactivated fetal calf serum in a 37ЊC, 5% CO 2 atmosphere. K562-DXR cells were maintained in 2 mmol/l doxorubicin containing medium and was 165-fold resistant to daunorubicin (Merlin et al, 1994).…”

“…The atypic cell population was selected by double lightscattering analysis (forward angle and right angle light scattering). Double-labelling flow cytometry analyses were carried out on cell suspensions containing 10 6 cells/ml using an Orthocyte ® flow cytometer (Ortho Diagnostic Systems, Roissy, France) according to the methodology already reported (Merlin et al, 1994). Briefly, intracellular daunorubicin accumulation (IDF) was assayed, after incubating the cells with 2 mmol/l daunorubicin (Cerubidine ® , Rhone Poulenc Rorer, Roger Bellon, Neuilly, France) for 2 h at 37ЊC.…”

“…We recently reported that the determination of intracellular accumulation of daunorubicin in AML cells correlated with PGP expression and was a significant independent prognostic factor having the highest predictive value for clinical response (Guerci et al, 1995). Many compounds have been investigated for PGP modulation in experimental models (Tsuruo et al, 1983;Ford & Hait, 1990;Dantzig et al, 1996;Merlin et al, 1994). In most cases, and despite encouraging preclinical results, the development of MDR-modulating agents has been impaired because of clinical toxicity occurring when high doses were administered to achieve plasma concentrations inducing PGP inhibition (Terret et al, 1996).…”