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ABSTRACT: We analyzed the cellular and molecular effects of two different histone deacetylase inhibitors (HDACi), MGCD0103 and vorinostat, in combination with GX15-070, a BH3-mimetic, in acute myeloid leukemia (AML) cell lines and primary AML cells, and demonstrated that the combination has a synergistic antileukemia effect. We observed that in addition to apoptosis, autophagy also accounts for the observed nonapoptotic decrease of cell viability. Mechanistically, we established a role for calpain activity and ER-located caspase signaling in the induction of both autophagy and apoptosis following this combination of drugs. These findings reveal that for this specific combination, autophagy plays a positive role in inducing cytotoxicity, and that the involved ER signaling networks, as well as their clinical relevance, should be further studied in both preclinical and clinical trials of leukemia and other malignancies.
Autophagy 10/2010; 6(7):976-8. · 7.45 Impact Factor
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Yue Wei,
Tapan Kadia, Weigang Tong,
Ming Zhang,
Yu Jia,
Hui Yang,
Yumin Hu,
Francesco Paolo Tambaro,
Jean Viallet,
Susan O'Brien,
Guillermo Garcia-Manero
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ABSTRACT: Single-agent histone deacetylase inhibitors (HDACi) have limited clinical activity in human leukemia. Although the way HDACi exert their antileukemia effect is not fully understood, it is accepted that induction of apoptosis is important. We hypothesized, therefore, that combination of an HDACi with a proapoptotic agent, such as the Bcl-2 homology domain-3 mimetic GX15-070, could result in enhanced antileukemia activity.
We analyzed the cellular and molecular effects of two different HDACi (MGCD0103 and vorinostat) in combination with GX15-070 in leukemia cell lines and primary acute myelogenous leukemia cells.
We showed that the combination had synergistic antileukemia effect both in leukemia cell lines and in primary acute myelogenous leukemia cells. Using molecular markers and electron microscopy, we observed that in addition to apoptosis, autophagy accounts for the nonapoptotic decrease in cell viability, an effect that could be inhibited by chloroquine, an inhibitor of autophagy. Finally, we established a role for calpain activity in the induction of both autophagy and apoptosis by this combination.
The combination of an HDACi and GX15-070 has synergistic antileukemia activity, and the effect is mediated by induction of apoptosis and autophagy. The combination should be studied in clinical trials of leukemia and the role of autophagy in leukemia therapy needs to be better understood.
Clinical Cancer Research 08/2010; 16(15):3923-32. · 7.74 Impact Factor
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ABSTRACT: Eph receptors and their ephrin ligands are involved in normal hematopoietic development and tumorigenesis. Using methylated CpG island amplification/DNA promoter microarray, we identified several EPH receptor and EPHRIN genes as potential hypermethylation targets in acute lymphoblastic leukemia (ALL). We subsequently studied the DNA methylation status of the Eph/ephrin family by bisulfite pyrosequencing. Hypermethylation of EPHA2, -A4, -A5, -A6, -A7, -A10, EPHB1, -B2, -B3, -B4, EFNA1, -A3, -A5, and EFNB1 and -B2 genes was detected in leukemia cell lines and primary ALL bone marrow samples. Expression analysis of EPHB4, EFNB2, and EFNA5 genes demonstrated that DNA methylation was associated with gene silencing. We cloned the promoter region of EPHB4 and demonstrated that promoter hypermethylation can result in EPHB4 transcriptional silencing. Restoration of EPHB4 expression by lentiviral transduction resulted in reduced proliferation and apoptotic cell death in Raji cells in which EPHB4 is methylated and silenced. Finally, we demonstrated that phosphorylated Akt is down-regulated in Raji cells transduced with EPHB4. These results suggest that epigenetic silencing by hypermethylation of EPH/EPHRIN family genes contributes to ALL pathogenesis and that EPHB4 can function as a tumor suppressor in ALL.
Blood 03/2010; 115(12):2412-9. · 9.90 Impact Factor
