LGP1, A histone deacetylase inhibitor analogue of FR235222, sensitizes promyelocytic leukaemia U937 cells to TRAIL-mediated apoptosis.
BACKGROUND
It has been shown that chemo-therapeutic agents, such as histone deacetylase inhibitors (HDACi), are able to increase TRAIL-induced apoptosis in many types of cancer. In the present study, we investigated the effects of the novel HDACi LGP1, a new simplified analogue of FR235222, in human leukaemia U937 cells resistant to TRAIL-induced apoptosis.


METHODS
U937 cells were incubated with TRAIL/LGP1 for 24 h and apoptosis was evaluated using flow cytometric assay and cleavage of caspase-3 and (PARP) by Western blot. Western blot analysis was also used to detect the expression of p21, p27, (NF-kappaB), Bcl-2 and the levels of H4 histone acetylation. Finally, flow cytometry was used to monitor the enhancement of TRAIL-receptor levels.


RESULTS
Treatment with LGP1 caused accumulation of acetylated histone H4 and G(1) cycle arrest accompanied by increase of p21. The compound was also able to sensitize U937 cells to TRAIL-induced apoptosis through multiple mechanisms: (i) activation of caspase-3 and cleavage of PARP; (ii) induction of p21 and p27; (iii) cleavage of NF-kappaB and down-regulation of Bcl-2. Finally, LGP1 induced up-regulation of TRAIL-R1 receptor expression.


CONCLUSIONS
These results demonstrate that U937 cells can be effectively killed by a combination treatment of subtoxic doses of LGP1 and TRAIL.
D'Acunto
Cosimo Walter
CW
Department of Pharmaceutical Science, University of Salerno, Via Ponte Don Melillo 84084 Fisciano (Salerno), Italy. apetrella@unisa.it
Carratù
Anna
A
Rodriquez
Manuela
M
Taddei
Maurizio
M
Parente
Luca
L
Petrella
Antonello
A
D000107:Acetylation / Q000187:drug effects; D017209:Apoptosis / Q000187:drug effects; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology*; D020169:Caspases / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D004357:Drug Synergism; D004789:Enzyme Activation; D016193:G1 Phase / Q000187:drug effects; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006657:Histones / Q000378:metabolism; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D010456:Peptides, Cyclic; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D020298:U937 Cells
D019086:Bridged Bicyclo Compounds, Heterocyclic; D056572:Histone Deacetylase Inhibitors; D006657:Histones; C549428:LGP1 compound; D010456:Peptides, Cyclic; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; D020169:Caspases