In vitro down-regulation of bcl-2 expression by all-trans retinoic acid in AML blasts

F. Pisani, G. Del Poeta, G. Aronica, A. Venditti, T. Caravita, S. Amadori

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Using flow cytometry, we have investigated the effects of 0.5 μM all-trans-retinoic acid (ATRA) on bcl-2 expression in the blast cells of 25 acute myeloblastic leukemia (AML) patients and the HL-60 cell line after incubation for 6 days. We observed a significant decrease of bcl-2 expression after treatment with ATRA in 12 of 25 AML samples and the HL-60 cells. The mean fluorescence intensity (MFI) ratio for the bcl-2 levels of the ATRA responders (n = 12) was reduced to 7.9 ± 4.8 following incubation with ATRA compared with 10.9 ± 6.5 (mean ± SD) for control samples incubated without ATRA (p = 0.011). There was no significant difference between the baseline bcl-2 MFI ratio in the ATRA responders (11.14 ± 7, n = 12) and the non responders (14.18 ± 11.3, n = 13; p = 0.432). The down-regulation of bcl-2 expression by ATRA was not significantly associated with CD34-negative or -positive AML. There was no correlation between AML subtypes and regulation of bcl-2 expression by ATRA. Complete remission and overall survival were not significantly improved in bcl-2 down-regulated cases. Our data confirm that ATRA can down-regulate the bcl-2 expression in AML blasts. Because many chemotherapeutic agents also operate through the activation of programmed cell death and bcl-2 levels are positively associated with resistance to apoptosis, ATRA can be used in combination chemotherapy to increase the chemosensitivity of some patients with AML.

Original languageEnglish
Pages (from-to)145-147
Number of pages3
JournalAnnals of Hematology
Issue number4
Publication statusPublished - Oct 1997


  • AML
  • ATRA
  • Bcl-2
  • CD34

ASJC Scopus subject areas

  • Hematology


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