Structure-Based Design of Grp94-Selective Inhibitors

Heat shock protein 90 KDa (Hsp90) belongs to family of proteins called molecular chaperone that are associated with protein folding and maturation. Hsp90 clients play a critical role in the pathogenesis of diseases such as cancer, neurodegeneration and infection. Currently, clinical trials are underway for various Hsp90 inhibitors, however, all of these inhibitors exhibit paninhibition of all four Hsp90 isoforms, which could be the cause of side effects observed with these inhibitors, including, hepatotoxicity, cardiotoxicity, and renal toxicity. Hence, the development of isoform selective Hsp90 inhibitor is needed to delineate the role each Hsp90 isoform plays towards the pathogenesis of these toxicities. One such isoform is the ER residing glucose regulated protein (Grp94), which is important for cellular communication and adhesion. Co-crystallization studies of radamide, an Hsp90 pan-inhibitor developed in our lab established that there exists a unique hydrophobic pocket found only in Grp94. To probe this pocket, two approaches have been investigated; 1) des-quinone analogs of radamide and 2) employing cis-amide isosteres. The co-crystal structure of cis-amide isostere compound BnIm bound to Gp94 and Hsp90 led to the discovery of a novel pocket in Grp94 due to ligand induced conformational change. This pocket has been probed by the modification of SNX 2112, a pan-inhibitor of Hsp90 that is currently undergoing clinical evaluation. These modifications have resulted in the identification of ACO1, which exhibits good potency and high selectivity towards Grp94. Rationale for the design of ACO analogs is discussed alongside their inhibition activities

Development of Glucose Regularted Protein 94-Selective Inhibitors Based on the Bnlm and Radamide Scaffold

Glucose regulated protein 94 (Grp94) is the endoplasmic reticulum resident of the heat shock protein 90 kDa (Hsp90) family of molecular chaperones. Grp94 associates with many proteins involved in cell adhesion and signaling, including integrins, Toll-like receptors, immunoglobulins, and mutant myocilin. Grp94 has been implicated as a target for several therapeutic areas including glaucoma, cancer metastasis, and multiple myeloma. While 85% identical to other Hsp90 isoforms, the N-terminal ATP-binding site of Grp94 possesses a unique hydrophobic pocket that was used to design isoform-selective inhibitors. Incorporation of a cis-amide bioisostere into the radamide scaffold led to development of the original Grp94-selective inhibitor, BnIm. Structure–activity relationship studies have now been performed on the aryl side chain of BnIm, which resulted in improved analogues that exhibit better potency and selectivity for Grp94. These analogues also manifest superior antimigratory activity in a metastasis model as well as enhanced mutant myocilin degradation in a glaucoma model compared to BnIm

Structure-guided design of an Hsp90â N-terminal isoform-selective inhibitor

The 90 kDa heat shock protein (Hsp90) is a molecular chaperone responsible for folding proteins that are directly associated with cancer progression. Consequently, inhibition of the Hsp90 protein folding machinery results in a combinatorial attack on numerous oncogenic pathways. Seventeen small-molecule inhibitors of Hsp90 have entered clinical trials, all of which bind the Hsp90 N-terminus and exhibit pan-inhibitory activity against all four Hsp90 isoforms. pan-Inhibition of Hsp90 appears to be detrimental as toxicities have been reported alongside induction of the pro-survival heat shock response. The development of Hsp90 isoform-selective inhibitors represents an alternative approach towards the treatment of cancer that may limit some of the detriments. Described herein is a structure-based approach to design isoform-selective inhibitors of Hsp90β, which induces the degradation of select Hsp90 clients without concomitant induction of Hsp90 levels. Together, these initial studies support the development of Hsp90β-selective inhibitors as a method to overcome the detriments associated with pan-inhibition

Grp94 selective inhibitors and uses thereof

The present technology provides compounds according to Formula I or Formula III as well as compositions including such compounds useful for the treatment of metastatic cancer and/or glaucoma

Development of Radamide Analogs as Grp94 Inhibitors

Hsp90 isoform-selective inhibition is highly desired as it can potentially avoid the toxic side-effects of pan-inhibition. The current study developed selective inhibitors of one such isoform, Grp94, predicated on the chimeric and pan-Hsp90 inhibitor, radamide (RDA). Replacement of the quinone moiety of RDA with a phenyl ring (2) was found to be better suited for Grp94 inhibition as it can fully interact with a unique hydrophobic pocket present in Grp94. An extensive SAR for this scaffold showed that substitutions at the 2- and 4-positions (8 and 27, respectively) manifested excellent Grp94 affinity and selectivity. Introduction of heteroatoms into the ring also proved beneficial, with a 2-pyridine derivative (38) exhibiting the highest Grp94 affinity (Kd = 820 nM). Subsequent cell-based assays showed that these Grp94 inhibitors inhibit migration of the metastatic breast cancer cell line, MDA-MB-231, as well as exhibit an anti-proliferative affect against the multiple myeloma cell line, RPMI 8226

Highly flame-retardant polyurethane foam based on reactive phosphorus polyol and limonene-based polyol

Polyurethane foams are in general flammable and their flammability can be controlled by adding flame-retardant (FR) materials. Reactive FR have the advantage of making strong bond within the polyurethane chains to provide excellent FR over time without compromising physico-mechanical properties. Here, phenyl phosphonic acid and propylene oxide-based reactive FR polyol was synthesized and used along with limonene based polyol for preparation of FR polyurethanes. All the obtained foams showed higher closed cell content (above 96%). By the addition of FR–polyol, the compressive strength of the foams showed 160% increment which could be due to reactive nature of FR–polyol. Moreover, 1.5 wt % of phosphorus (P) content reduced the self-extinguishing time of the foam from 81 (28% weight loss) to 11.2 s (weight loss of 9.8%). Cone test showed 68.6% reduction in peak heat release rate along with 23.4% reduction in thermal heat release. The change in char structure of carbon after burning was analyzed using Raman spectra which, suggests increment in the graphitic phase of the carbon over increased concentration of phosphorus. It can be concluded from this study that phosphorous based polyol could be blended with bio-based polyols to prepare highly FR and superior physico-mechanical rigid polyurethane foams. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46224

The Alpha Isoform of Heat Shock Protein 90 and the Co-chaperones p23 and Cdc37 Promote Opioid Anti-nociception in the Brain

Opioid activation of the mu opioid receptor (MOR) promotes signaling cascades that evoke both analgesic responses to pain and side effects like addiction and dependence. Manipulation of these cascades, such as by biased agonism, has great promise to improve opioid therapy. However, the signaling cascades of the MOR are in general poorly understood, providing few targets for drug development. In our earlier work, we identified Heat shock protein 90 (Hsp90) as a novel and crucial regulator of opioid anti-nociception in the brain by promoting ERK MAPK activation. In this study, we sought to identify the molecular isoforms and co-chaperones by which Hsp90 carried out this role, which could provide specific targets for future clinical intervention. We used novel selective small molecule inhibitors as well as CRISPR/Cas9 gene editing constructs delivered by the intracerebroventricular (icv) route to the brains of adult CD-1 mice to target Hsp90 isoforms (Hsp90α/β, Grp94) and co-chaperones (p23, Cdc37, Aha1). We found that inhibition of the isoform Hsp90α fully blocked morphine anti-nociception in a model of post-surgical paw incision pain, while blocking ERK and JNK MAPK activation, suggesting Hsp90α as the main regulator of opioid response in the brain. We further found that inhibition of the co-chaperones p23 and Cdc37 blocked morphine anti-nociception, suggesting that these co-chaperones assist Hsp90α in promoting opioid anti-nociception. Lastly, we used cycloheximide treatment in the brain to demonstrate that rapid protein translation within 30 min of opioid treatment is required for Hsp90 regulation of opioid response. Together these studies provide insight into the molecular mechanisms by which Hsp90 promotes opioid anti-nociception. These findings thus both improve our basic science knowledge of MOR signal transduction and could provide future targets for clinical intervention to improve opioid therapy.Arizona Biomedical Research Commission New Investigator Award [ADHS18-198875]; University of Arizona; Presbyterian College; National Institutes of Health (NIH)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R01CA213566]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Highly flame-retardant bio-based polyurethanes using novel reactive polyols

Poor flame retardancy of polyurethanes (PU) is a global issue as it limits their applications particularly in construction, automobile, and household appliances industries. The global challenge of high flammability of PU can be addressed by incorporating flame-retardant materials. However, additive flame-retardants are non-compatible and depreciate the properties of PU. Hence, reactive flame-retardants (RFR) based on aliphatic (Ali-1 and Ali-2) and aromatic (Ar-1 and Ar-2) structured bromine compounds were synthesized and used to prepare bio-based PU using limonene dimercaptan. The aromatic bromine containing foams showed higher close cell content (average 97 and 100%) and compressive strength (230 and 325 kPa) to that of aliphatic bromine containing foams. Similar behavior was observed for a horizontal burning test where with a low concentration of bromine (5 wt %) in the foams for Ar-1 and Ar-2 displayed a burning time of 12.5 and 11.8 s while, Ali-1 and Ali-2 displayed burning time of 25.7 and 37 s, respectively. Neat foam showed a burning time of 74 s. The percentage weight loss for neat PU foam was 26.5%, while foams containing 5 wt % bromine in Ali-1, Ali-2, Ar-1, and Ar-2 foams displayed weight loss of 11.3, 14, 7.9, and 14%, respectively. Our results suggest that flame retardant PU foams could be prepared effectively by using RFR materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46027

Transformation of the Non-Selective Aminocyclohexanol-Based Hsp90 Inhibitor into a Grp94-Seletive Scaffold

Glucose regulated protein 94 kDa, Grp94, is the endoplasmic reticulum (ER) localized isoform of heat shock protein 90 (Hsp90) that is responsible for the trafficking and maturation of toll-like receptors, immunoglobulins, and integrins. As a result, Grp94 has emerged as a therapeutic target to disrupt cellular communication, adhesion, and tumor proliferation, potentially with fewer side effects compared to <i>pan</i>-inhibitors of all Hsp90 isoforms. Although, the N-terminal ATP binding site is highly conserved among all four Hsp90 isoforms, recent cocrystal structures of Grp94 have revealed subtle differences between Grp94 and other Hsp90 isoforms that has been exploited for the development of Grp94-selective inhibitors. In the current study, a structure-based approach has been applied to a Grp94 nonselective compound, SNX 2112, which led to the development of <b>8j</b> (<b>ACO1</b>), a Grp94-selective inhibitor that manifests ∼440 nM affinity and >200-fold selectivity against cytosolic Hsp90 isoforms

Inhibition of Hsp90 in the spinal cord enhances the antinociceptive effects of morphine by activating an ERK-RSK pathway

Morphine and other opioids are commonly used to treat pain despite their numerous adverse side effects. Modulating mu-opioid receptor (MOR) signaling is one way to potentially improve opioid therapy. In mice, the chaperone protein Hsp90 mediates MOR signaling within the brain. Here, we found that inhibiting Hsp90 specifically in the spinal cord enhanced the antinociceptive effects of morphine in mice. Intrathecal, but not systemic, administration of the Hsp90 inhibitors 17-AAG or KU-32 amplified the effects of morphine in suppressing sensitivity to both thermal and mechanical stimuli in mice. Hsp90 inhibition enabled opioid-induced phosphorylation of the kinase ERK and increased abundance of the kinase RSK in the dorsal horns of the spinal cord, which are heavily populated with primary afferent sensory neurons. The additive effects of Hsp90 inhibition were abolished upon intrathecal inhibition of ERK, RSK, or protein synthesis. This mechanism downstream of MOR, localized to the spinal cord and repressed by Hsp90, may potentially be used to enhance the efficacy and presumably decrease the side effects of opioid therapy.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]