Calcein assay for multidrug resistance reliably predicts therapy response and survival rate in acute myeloid leukaemia

Abstract

Summary. In this study, we evaluated the suitability of the calcein assay as a routine clinical laboratory method for the identification of multidrug-resistant phenotype in acute leukaemia. This study presents the results of the calcein tests obtained in two large haematological centres in Hungary. Assays were performed with blast cells of 93 de novo acute leukaemia patients, including 65 patients with acute myeloid leukaemia (AML). Results were expressed as multidrug resistance activity factor (MAF) values. AML patients were divided into responders and non-responders and MAF values were calculated for each group. In both centres, responder patients displayed significantly lower MAF values than non-responders (P 0´0045 and P 0´0454). Cut-off values were established between the MAF R 1 SEM and MAF NR 2 SEM values. On the basis of these cut-off levels, multidrug resistance (MDR) negativity showed a 72% predictive value for the response to chemotherapy, whereas MDR positivity was found to have an average predictive value of 69% for therapy failure. MDR activity was a prognostic factor for survival rate and the test was suitable for detecting patients at relapse. The calcein assay can be used as a quantitative, standardized, inexpensive screening test in a routine clinical laboratory setting. The assay detects both P-glycoprotein and multidrug resistance-associated protein activities, and identifies AML patients with unfavourable therapy responses.

Complementary effects of HDAC inhibitor 4-PB on gap junction communication and cellular export mechanisms support restoration of chemosensitivity of PDAC cells

“…The product of this enzymatic reaction, calcein, is a strong fluorescent. Thus, the fluorescence intensity of a cell inversely correlates with the cellular export (Karaszi et al, 2001). Pancreatic carcinoma cell lines Panc 1, BxPc3, T3M-4 and COLO 357 were treated with 0.0, 2.0, 5.0 or 10.0 mM 4-PB or 100 mM verapamil, a known inhibitor of MDR1-mediated efflux (Hindenburg et al, 1987) as a control to assure an adequate experimental design.…”

“…After 2 h, cells were trypsinised, washed two times and resuspended in PBS. The intracellular accumulation of the dye was determined by cell cytometry (Karaszi et al, 2001). …”

Inhibition of P-glycoprotein-mediated multidrug resistance by unfractionated heparin: A new potential chemosensitizer for cancer therapy

“…The functional ability of Pgp was tested by measuring intracellular retention of the MDR Pgp-mediated marker, calcein acetoxymethylester (calcein-AM). [20][21][22] This hydrophobic fluorescent molecule is actively transported by transmembrane efflux pump, thereby its intracellular signal levels give a measure of the level of expression of MDR-Pgp in cancer cells and an indication of the degree to which the pump is or is not blocked by Pgp inhibitors. The modifying effects of UFH on Pgp activity were studied by cytoplasmatic doxorubicin (doxo) accumulation assay, a known Pgp substrate, which is frequently used for the antineoplastic treatment of human breast cancer in combination with other chemotherapeutic agents.…”

A New Taxoid from a Callus Culture of Taxus cuspidata as an MDR Reversal Agent

“…25,26) The typical MDR reversal agent, verapamil, increases the accumulation of calcein in MDR cells and overcomes MDR. 21,22) The effects of compounds 1 and 2 on the cellular accumulation of calcein in MDR human ovarian cancer 2780AD cells were examined by comparison with that of verapamil.…”