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Br J Haematol. 2009 Feb;144(3):358-66. doi: 10.1111/j.1365-2141.2008.07484.x. Epub 2008 Nov 13.

The heat shock protein 90 inhibitor IPI-504 induces apoptosis of AKT-dependent diffuse large B-cell lymphomas.

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Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.


Heat shock protein 90 (HSP90) is a molecular chaperone that stabilizes critical client proteins in multiple cancers. Gene expression profiling was utilized to characterize HSP90 isoform expression in primary human diffuse large B-cell lymphomas (DLBCLs). HSP90 alpha and beta isoforms were differentially expressed in subsets of tumours defined by their transcriptional profiles. Thereafter, we assessed the activity of the HSP90 inhibitor, IPI-504, in an extensive panel of DLBCL cell lines. IPI-504, which interacts with the conserved ATP-binding site in both HSP90 isoforms, inhibited proliferation and induced apoptosis in the majority of DLBCL cell lines at low micromolar concentrations. IPI-504-sensitive cell lines expressed high levels of the HSP90 client protein, pAKT, and exhibited dose-dependent decreases in pAKT levels following IPI-504 treatment and significantly reduced proliferation following AKT RNAi. Furthermore, the combination of low-dose (<1 micromol/l) IPI-504 and the AKT/Pi3K pathway inhibitor, LY24009, was synergistic in IPI-504-sensitive DLBCL cell lines. Low-dose IPI-504 was also synergistic with the chemotherapeutic agent, doxorubicin. The HSP90 inhibitor IPI-504 warrants further investigation in DLBCL alone and in combination with identified client protein inhibitors and active chemotherapeutic agents.

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