A purine scaffold Hsp90 inhibitor destabilizes BCL-6 and has specific antitumor activity in BCL-6-dependent B cell lymphomas.
We report that heat shock protein 90 (Hsp90) inhibitors selectively kill diffuse large B cell lymphomas (DLBCLs) that depend on the BCL-6 transcriptional repressor. We found that endogenous Hsp90 interacts with BCL-6 in DLBCL cells and can stabilize BCL-6 mRNA and protein. Hsp90 formed a complex with BCL-6 at its target promoters, and Hsp90 inhibitors derepressed BCL-6 target genes. A stable mutant of BCL-6 rescued DLBCL cells from Hsp90 inhibitor-induced apoptosis. BCL-6 and Hsp90 were almost invariantly coexpressed in the nuclei of primary DLBCL cells, suggesting that their interaction is relevant in this disease. We examined the pharmacokinetics, toxicity and efficacy of PU-H71, a recently developed purine-derived Hsp90 inhibitor. PU-H71 preferentially accumulated in lymphomas compared to normal tissues and selectively suppressed BCL-6-dependent DLBCLs in vivo, inducing reactivation of key BCL-6 target genes and apoptosis. PU-H71 also induced cell death in primary human DLBCL specimens.
Cerchietti
Leandro C
LC
Division of Hematology and Oncology, Weill Cornell Medical College of Cornell University, New York, New York, USA.
Lopes
Eloisi C
EC
Yang
Shao Ning
SN
Hatzi
Katerina
K
Bunting
Karen L
KL
Tsikitas
Lucas A
LA
Mallik
Alka
A
Robles
Ana I
AI
Walling
Jennifer
J
Varticovski
Lyuba
L
Shaknovich
Rita
R
Bhalla
Kapil N
KN
Chiosis
Gabriela
G
Melnick
Ari
A
D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D006801:Humans; D016393:Lymphoma, B-Cell / Q000378:metabolism* / Q000473:pathology; D011485:Protein Binding; D051560:Proto-Oncogene Proteins c-bcl-6
C084103:BCL6 protein, human; D004268:DNA-Binding Proteins; D018841:HSP90 Heat-Shock Proteins; D051560:Proto-Oncogene Proteins c-bcl-6