ABSTRACT
Acute myeloid leukemia (AML) patients' outcome is usually poor, mainly because of drug resistance phenotype. The identification of new drugs able to overcome mechanisms of chemoresistance is essential. The pterocarpanquinone LQB-118 compound has been shown to have a potent cytotoxic activity in myeloid leukemia cell lines and patient cells. Our aim was to investigate if LQB-118 is able to target FoxO3a and FoxM1 signaling pathways while sensitizing AML cell lines. LQB-118 induced apoptosis in both AML cell lines HL60 (M3 FAB subtype) and U937 (M4/M5 FAB subtype). Cell death occurred independently of alterations in cell cycle distribution. In vivo administration revealed that LQB-118 was not cytotoxic to normal bone marrow-derived cells isolated from mice. LQB-118 induced FoxO3a nuclear translocation and upregulation of its direct transcriptional target Bim, in HL60 cells. However, LQB-118 induced FoxO3a nuclear exclusion, followed by Bim downregulation, in U937 cells. Concomitantly, LQB-118 exposure reduced FoxM1 and Survivin expression in U937 cells, but this effect was more subtle in HL60 cells. Taken together, our data suggest that LQB-118 has a selective and potent antitumor activity against AML cells with distinct molecular subtypes, and it involves differential modulation of the signaling pathways associated with FoxO3a and FoxM1 transcription factors.
Subject(s)
Forkhead Transcription Factors/biosynthesis , Leukemia, Myeloid, Acute/drug therapy , Naphthoquinones/administration & dosage , Pterocarpans/administration & dosage , Animals , Apoptosis/drug effects , Cell Cycle/drug effects , Cell Line, Tumor , Forkhead Box Protein M1 , Forkhead Box Protein O3 , Gene Expression Regulation, Leukemic/drug effects , HL-60 Cells , Humans , Leukemia, Myeloid, Acute/genetics , Leukemia, Myeloid, Acute/pathology , MiceABSTRACT
Naturally occurring pterocarpans 1a,b, pterocarpan 1c, isoflavane 2 and ortho-quinone 3 were synthesized in the racemic form and their cytotoxic effect was evaluated on the human leukemia cell lines K562 (resistant to oxidative stress), Lucena-1 (MDR phenotype) and HL-60. Ortho-quinone 3 (IC(50)=1.5 microM, 1.8 microM and 0.2 microM, respectively) and catechol pterocarpan 1a (IC(50)=3.0 microM, 3.7 microM and 2.1 microM, respectively) were the most active compounds on these cells and were also evaluated on other human leukemia cell lines (Jurkat and Daudi). Ortho-quinone 3 was 2 to 10 times more potent than pterocarpan 1a, depending on the cell line considered, however, showed a greater toxicity for lymphocytes activated by PHA.
