Early induction of apoptosis in B-chronic lymphocytic leukaemia cells by hydroxychloroquine: activation of caspase-3 and no protection by survival factors.
We have investigated the effect of hydroxychloroquine (HCQ), an anti-rheumatic drug, on malignant B cells from 20 patients with B-chronic lymphocytic leukaemia (B-CLL). HCQ induced a decrease in cell viability in a dose- and time-dependent manner. The mean IC50 was 32 +/- 7 microg/ml (range, 10-75 microg/ml) for 24 h of exposure. This cytotoxic effect was owing to apoptosis, as demonstrated by morphological changes, annexin V binding capacity and DNA fragmentation (28 +/- 4% of apoptotic cells as early as 5 h post incubation, increasing to 82 +/- 4% at 18 h post treatment). The apoptosis was associated with caspase-3 activation because the cleavage and activity of caspase-3 were increased by HCQ. The amount of bcl-2 protein was reduced during apoptosis, evidenced using quantitative flow cytometry. As early as 1 h post-HCQ treatment, a reduction of the mitochondrial transmembrane potential was measured by 3,3'-dihexyloxacarbocyanine iodide. Interestingly, the HCQ effect was not affected by exposure to interleukin-4 or co-culture with bone marrow stromal cells. Our observations suggest that HCQ may offer a new therapeutic tool in the treatment of B-CLL patients.
Lagneaux
L
L
Laboratoire d'Hématologie Expérimentale, Institut Jules Bordet, Brussels, Belgium. laurence.lagneaux@bordet.be
Delforge
A
A
Carlier
S
S
Massy
M
M
Bernier
M
M
Bron
D
D
D000368:Aged; D000369:Aged, 80 and over; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D006886:Hydroxychloroquine / Q000627:therapeutic use*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy* / Q000473:pathology; D008297:Male; D008564:Membrane Potentials; D008875:Middle Aged; D008928:Mitochondria / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects*
D018501:Antirheumatic Agents; D019253:Proto-Oncogene Proteins c-bcl-2; D006886:Hydroxychloroquine; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases