Quantitative determination of mdr1 gene expression in leukaemic cells from patients with acute leukaemia

Abstract

Summary By using a quantitative RNA-RNA solution hybridisation method, the average number of mdrl RNA transcripts per cell was measured in total nucleic acid extracts of leukaemic cells from patients with acute leukaemia. The results in different types of leukaemia were (number of patients with detectable mdrl RNA/total number of patients; median number of transcripts per cell in samples with detectable mdrl RNA); de novo untreated acute myelocytic leukaemia (AML): 20/44; 0.7, secondary acute myelocytic leukaemia: 8/13; 1.1, acute lymphocytic (ALL) and undifferentiated leukaemia: 5/14; 0.6, relapsed leukaemia: 7/15; 0.7. Forty-six patients with de novo untreated acute leukaemia (AML: n = 34, ALL: n = 12) were evaluable for response to induction chemotherapy. Twelve of 18 patients (67%) with detectable mdrl RNA levels achieved complete remission compared to 23 of 28 (82%) with undetectable levels (P = 0.40). The remission duration tended to be longer among patients with undetectable mdrl RNA (P = 0.08). Leukaemic cells were analysed on consecutive occasions in 12 patients. The level of expression increased in four and decreased in two. In conclusion, expression of mdrl RNA is common in acute untreated leukaemia. However, treatment with cytostatic drugs seems only rarely to increase the proportion of leukaemic cells that express mdrl RNA. Expression of the mdrl gene could be one of several equally important factors contributing to drug resistance in acute leukaemia.

Uptake of anthracyclines in vitro and in vivo in acute myeloid leukemia cells in relation to apoptosis and clinical response

“…Apoptosis, which was evaluated after 18 h, was determined from caspase 3 activation and phosphatidylserine exposure using flow cytometry. Attempts have also been made to find correlations between in vitro drug uptake, P-gp expression, and clinical outcome [32][33][34].…”

P-glycoprotein and glutathione S-transferase pi in childhood acute lymphoblastic leukaemia

“…Using immunohistochemical methods (Musto et al, 1990) or immunoblot techniques (Kuwazuru et al, 1990) P-170 expression was found in six out of 12 and in four out of 11 adult ALL patients respectively. In addition, increased MDR-J mRNA transcripts were found in five of 14 adults with ALL (Gruber et al, 1992). In a recent work Goasguen et al (1993) found P-170 expression in 12 out of 36 children (33%) with newly diagnosed ALL.…”

Multidrug resistance phenotype in leukaemic cells from patients with acute myelocytic leukaemia can be detected with 99Tcm-MIBI

“…K562/Vcr3O and K562fVcrl50 expressed approximately 100 and 200 mdrl mRNA transcripts per cell, respectively, as determined by a quantitative RNAase protection assay (Gruber et al, 1992 Leukaemic cells Peripheral leukaemic cells from ten patients with AML were used. Cells isolated on Lymphoprep (Nycomed, Pharma, AS, Norway) were frozen in a programmed freezer and kept in liquid nitrogen.…”

“…The viability of the cells after thawing was controlled with trypan blue exclusion and was 70% and 73% in two samples; in the remaining, the viability was over 85%. The samples were chosen according to their mdrl mRNA expression, which was determined earlier with a quantitative RNAase protection assay (Gruber et al, 1992). Cells from five of the patients had no detectable mdrl mRNA levels, and cells from five patients had mdrl mRNA levels ranging from 1.0 to 3.8 mdrl mRNA transcripts per cell.…”

“…Using a quantitative RNAase protection assay, we found the median level of mdrl mRNA in positive cell samples from patients with AML to be 0.7 mdrl mRNA transcripts per cell (Gruber et al, 1992). In two vincristine-selected K562 cell lines, the levels were approximately 100 and 200 transcripts per cell.…”