The heat shock response and small molecule regulators

Abstract Background: Even with the prevalent usage of specified treatment protocols, treatment gap remains and besides that the conventional therapies used routinely inflict significant toxicity due to low specificity. Therefore, the development of novel targeted therapies which are active against resistant leukemia subtypes and at the same time offer low toxicity in patients is of high importance. We, therefore, aimed to develop and characterize novel precision compounds, which target oncogene stabilization via HSP90 axis. Aims: We have previously developed a novel peptidomimetic HSP90 inhibitor (AX) which was active as a pan-leukemia inhibitor against LSCs without inducing any Heat Shock Resoponse (HSR). However due to peptidomimetic nature and high molecular weight, the clinical implication of AX was limited. Therefore, using the previous knowledge we focused on developing second generation of small molecule inhibitor against the C-terminal dimerization of HSP90 with better efficacy and clinical potential. Methods: We have generated the library of small molecule inhibitor targeting HSP90 C-terminus and selected the most potent analogue (VWK147) depending upon its higher potency against leukemic/cancerous cells. The specificity of VWK147 was further evaluated by microscale thermophoresis (MST), cell-based luciferase refolding assay, 2D NMR spectroscopy, analytical ultracentrifugation and molecular dynamics simulations. Results: HSP90 act as molecular chaperone and is highly expressed in several therapy-resistant leukemia subtypes thereby ensuring correct protein folding of several oncogenic proteins such as BCR-ABL1, FLT3-ITD and AKT. Therefore, targeting HSP90 could be a promising option in the treatment of therapy-refractory leukemia. Majority of available HSP90 inhibitors target the N-terminal domain thereby induce a protective mechanism called heat shock response (HSR), which potentially weakens the cytotoxic effect of HSP90 inhibitors and induce toxicity. We have now developed first in class small molecule HSP90 C-terminal dimerization inhibitor 'VWK147' through structure-based molecular design and chemical synthesis which specifically targets C-terminal dimerization of HSP90. Like AX, VWK147 destabilizes BCR-ABL oncoprotein and its related pro-oncogenic cellular response (involving proliferation, apoptosis and differentiation), effective in preclinical AML and TKI (2nd and 3rd generation) resistant cell line models in vitro and induces apoptosis in primary AML and BCR-ABL1+ BCP-ALL patient derived leukemic cell, without inducing any HSR. The next step would be to to evaluate its in vivo activity and pharmacodynamic profiling. Conclusion: Taken together, VWK147 represents a promising next step for future efforts towards the development of novel targeted HSP90 inhibitors to overcome drug resistance and reduce toxicity, especially for the treatment of relapsed/refractory ALL. References:Bhatia S, Diedrich D, Frieg B, et al. Targeting HSP90 dimerization via the C terminus is effective in imatinib-resistant CML and lacks the heat shock response. Blood. 2018;132(3):307-320.John C. Byrd. HSP90 inhibition without heat shock response. Blood commentary 2018. doi: https://doi.org/10.1182/blood-2018-05-850271. Disclosures No relevant conflicts of interest to declare.

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Small Molecule Inducers of Heat-Shock Response Reduce polyQ-Mediated Huntingtin Aggregation

Neurodegenerative Diseases ◽

10.1159/000101849 ◽

2007 ◽

Vol 4 (2-3) ◽

pp. 254-260 ◽

Cited By ~ 44

Author(s):

Martin Herbst ◽

Erich E. Wanker

Keyword(s):

Heat Shock ◽

Small Molecule ◽

Heat Shock Response ◽

Shock Response

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Abstract 106: A Novel Small Molecule Protects Against Myocardial Ischemia and Doxorubicin-Induced Cardiomyopathy Through Heat Shock Response and Proteostasis Regulation In Vivo

Circulation Research ◽

10.1161/res.111.suppl_1.a106 ◽

2012 ◽

Vol 111 (suppl_1) ◽

Author(s):

Sudhish Sharma ◽

Savitha Deshmukh ◽

Manuela Zampino ◽

Brandon Walker ◽

Sunjay Kaushal

Keyword(s):

Heat Shock ◽

Small Molecule ◽

Heat Shock Response ◽

Myocardial Injury ◽

Heart Function ◽

Myocardial Infarct Size ◽

Mrna Levels ◽

Cell Based Therapy ◽

Shock Response

Background: A potentially new non-cell-based therapy is the systemic delivery of small molecules to revive or protect injured myocardium. By screening a drug library, we identified a novel small molecule, sk421, and tested its effectiveness in two myocardial injury models in vivo: a myocardial infarction model and doxorubicin (DOX)-induced cardiomyopathy model. Results: Sk421 significantly increased cellular viability of DOX-injured cardiomyocytes by preventing apoptosis in vitro, demonstrated by assays for MTT (p=0.042), annexin-V, and active caspase-3 (p=0.004). Sk421 increased the concentrations of the GATA4 and the heat shock proteins (HSPs) in cardiomyocytes (by 1.5-fold), and fibroblasts (by 1.2-fold), but was unable to rescue DOX-injured fibroblast cells depleted of HSPs. Sk421 maintained the total proteosome by a 3.5-fold inhibition of ubiquitinized GATA4 degradation, as shown by immunoprecipitation assays. Oral administration of sk421(4mg/kg) rescued DOX-injured mice by significantly preserving cardiac function, weight gain, cardiomyocyte lesion size and abundance, and by reducing overall mortality (20% in treated groups) compared to control DOX-injured mice (80% in untreated groups, p<0.03). The levels of GATA4 and HSPs were increased in the sk421-rescued mice. In the MI model, (n=5/group), sk421 reduced myocardial infarct size, and protected heart function evaluated by ejection fraction 45.8 ± 2.4 vs. 34.8 ± 3.3, p=0.005 (day7), and 44.3 ± 2.8 vs. 34.4 ± 4.1, p=0.011 (day28). Sk421 treatment of MI rats resulted in a higher fraction of viable tissue (within the LV (70.20 ± 0.5024, n=3) as compared to only MI group (56.38 ± 3.879%, n=3) and the infiltration of CD68+ cells was found to be more in the infarct region of LV of MI group rats as compared to MI+CEL. Quantitative analysis showed a significantly higher proportion of TUNEL positive cells and mRNA levels of IL-1β, IL-6, TNF-α and MMP2 in the myocardium of MI rats compared to MI+SK421 rats. Conclusion: This study demonstrates the broad therapeutic benefit of sk421 in animal model of myocardial injury by mechanism of inducing the heat shock response and preserving GATA levels. The ease of oral delivery makes sk421 a potentially clinically useful adjunct for myocardial preservation.

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