The HSP90 inhibitor 17-AAG synergizes with doxorubicin and U0126 in anaplastic large cell lymphoma irrespective of ALK expression.
OBJECTIVE
Heat shock protein 90 (HSP90) chaperones and maintains the molecular integrity of a variety of signal transduction proteins, including the nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) oncogenic protein, a genetic abnormality that is frequently observed in anaplastic large cell lymphoma (ALCL) cells. Here we demonstrate that HSP90 is overexpressed in primary and cultured ALK-positive and ALK-negative ALCL cells, and we evaluate the potential role of the small molecule inhibitor of HSP90, 17-allylamino-17-demethoxygeldanamycin (17-AAG) in treating ALCL.


METHODS
The antiproliferative effect of 17-AAG-cultured cells was determined by MTS assay. Apoptosis and cell-cycle arrest were determined by Annexin-V/propidium iodide and propidium iodide staining, respectively, and fluorescein-activated cell sorting analysis. Expression of HSP90 was evaluated by immunohistochemistry, and molecular changes were determined by Western blot.


RESULTS
Treatment of cultured ALCL cells with 17-AAG induced cell-cycle arrest and apoptosis, irrespective of ALK expression. At the molecular level, 17-AAG induced degradation of ALK and Akt proteins, dephosphorylated extracellular signal-regulated kinase, and degraded the cell-cycle regulatory protein cyclin D1 and its cyclin-dependent kinases, CDK4 and CDK6, but had a differential effect on p27 and p53 proteins. Inhibition of extracellular signal-regulated kinase phosphorylation by the mitogen activated protein kinase inhibitor U0126 induced cell death in all ALCL cell lines, and sublethal concentration 17-AAG showed synergistic antiproliferative effects when combined with U0126 or doxorubicin.


CONCLUSIONS
Our data demonstrate that targeting HSP90 function by 17-AAG may offer a novel therapeutic strategy for ALCL, either as single-agent activity or by combining 17-AAG with conventional or targeted therapeutic schemes.
Georgakis
Georgios V
GV
Departments of Lymphoma and Myeloma, The University of Texas, M.D. Anderson Cancer Center, Houston, TX 77030, USA.
Li
Yang
Y
Rassidakis
Georgios Z
GZ
Medeiros
L Jeffrey
LJ
Younes
Anas
A
D000077548:Anaplastic Lymphoma Kinase; D017209:Apoptosis / Q000187:drug effects; D016227:Benzoquinones / Q000494:pharmacology*; D002070:Butadienes / Q000494:pharmacology*; D053148:Caspase 3 / Q000187:drug effects / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D056741:Cyclin D; D051358:Cyclin-Dependent Kinase 4 / Q000187:drug effects / Q000378:metabolism; D051361:Cyclin-Dependent Kinase 6 / Q000187:drug effects / Q000378:metabolism; D016213:Cyclins / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004317:Doxorubicin / Q000494:pharmacology*; D004357:Drug Synergism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects / Q000378:metabolism; D016193:G1 Phase / Q000187:drug effects; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology*; D017728:Lymphoma, Large-Cell, Anaplastic / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000187:drug effects / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis* / Q000187:drug effects; D020794:Receptor Protein-Tyrosine Kinases; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D013997:Time Factors
D016227:Benzoquinones; D002070:Butadienes; D056741:Cyclin D; D016213:Cyclins; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D009570:Nitriles; C113580:U 0126; C112765:tanespimycin; D004317:Doxorubicin; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; C495900:CDK4 protein, human; C495911:CDK6 protein, human; D051358:Cyclin-Dependent Kinase 4; D051361:Cyclin-Dependent Kinase 6; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D053148:Caspase 3