Mechanistic insight into WEB-2170-induced apoptosis in human acute myelogenous leukemia cells: the crucial role of PTEN.
OBJECTIVE
This study aimed to investigate the mechanisms of action of WEB-2170, an inverse agonist of platelet-activating factor receptor, capable of inducing apoptosis in human acute myelogenous leukemia (AML) cells.


METHODS
Gene expression profiling followed by cytofluorimetric, morphologic, and biologic analyses were used to monitor WEB-2170 effects in AML cell lines (ie, NB4, KG1, NB4-MR4, THP1, and U937) and blasts from patients with different AML (M0-M5) subtypes. PTEN silencing with small interfering RNA was also performed.


RESULTS
We have demonstrated that drug-mediated cytostasis/apoptosis in NB4 cells is characterized by upregulation of cyclin G2, p21/WAF1, NIX, TNF-alpha, and PTEN expression, and downregulation of cyclin D2 and BCL2 expression. We observed an increase in PTEN protein accompanied by a decrease in phospho-extracellular signal-regulated kinase 2 (ERK2) and phospho-AKT, and by forkhead box O3a (FOXO3a) cytoplasmic-nuclear translocation; the mitochondrial cytochrome C release and PARP cleavage marked the late apoptotic steps. We have found that WEB-2170 triggered apoptosis in NB4, KG1, and NB4-MR4 cells where PTEN was expressed, but not in THP1 and U937 cells where PTEN was absent. Finally, we show that PTEN silencing in NB4 cells by PTEN-specific small interfering RNA resulted in a significant reduction of drug-induced apoptosis.


CONCLUSIONS
We demonstrated that WEB-2170 is a powerful antileukemic agent with interesting translational opportunities to treat AML and described mechanisms of drug-induced intrinsic and extrinsic apoptosis both in AML cell lines and blasts from AML patients by addressing PTEN as the master regulator of the whole process.
Cellai
Cristina
C
Department of Experimental Pathology and Oncology, University of Florence, 50134 Florence, Italy.
Laurenzana
Anna
A
Bianchi
Elisa
E
Sdelci
Sara
S
Manfredini
Rossella
R
Vannucchi
Alessandro M
AM
Caporale
Roberto
R
Balliu
Manjola
M
Mannelli
Francesco
F
Ferrari
Sergio
S
Bosi
Alberto
A
Miniati
Debora
D
Cocco
Pier L
PL
Veronneau
Steeve
S
Stankova
Jana
J
Paoletti
Francesco
F
D000208:Acute Disease; D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001381:Azepines / Q000494:pharmacology*; D045744:Cell Line, Tumor / Q000187:drug effects; D005260:Female; D020869:Gene Expression Profiling; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007951:Leukemia, Myeloid / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000473:pathology; D051059:PTEN Phosphohydrolase / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D016133:Polymerase Chain Reaction; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000494:pharmacology; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D014230:Triazoles / Q000494:pharmacology*; D055815:Young Adult
D000970:Antineoplastic Agents; D001381:Azepines; D009363:Neoplasm Proteins; D034741:RNA, Small Interfering; D014230:Triazoles; C063964:bepafant; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human