Hyperthermia Selectively Destabilizes Oncogenic Fusion Proteins.

The PML/RARα fusion protein is the oncogenic driver in acute promyelocytic leukemia (APL). Although most APL cases are cured by PML/RARα-targeting therapy, relapse and resistance can occur due to drug-resistant mutations. Here we report that thermal stress destabilizes the PML/RARα protein, including clinically identified drug-resistant mutants. AML1/ETO and TEL/AML1 oncofusions show similar heat shock susceptibility. Mechanistically, mild hyperthermia stimulates aggregation of PML/RARα in complex with nuclear receptor corepressors leading to ubiquitin-mediated degradation via the SIAH2 E3 ligase. Hyperthermia and arsenic therapy destabilize PML/RARα via distinct mechanisms and are synergistic in primary patient samples and in vivo, including three refractory APL cases. Collectively, our results suggest that by taking advantage of a biophysical vulnerability of PML/RARα, thermal therapy may improve prognosis in drug-resistant or otherwise refractory APL. These findings serve as a paradigm for therapeutic targeting of fusion oncoprotein-associated cancers by hyperthermia. SIGNIFICANCE: Hyperthermia destabilizes oncofusion proteins including PML/RARα and acts synergistically with standard arsenic therapy in relapsed and refractory APL. The results open up the possibility that heat shock sensitivity may be an easily targetable vulnerability of oncofusion-driven cancers.See related commentary by Wu et al., p. 300.

Discovery of indolylpiperazinylpyrimidines with dual-target profiles at adenosine A2A and dopamine D2 receptors for Parkinson's disease treatment.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive loss of dopaminergic neurons in the substantia nigra of the human brain, leading to depletion of dopamine production. Dopamine replacement therapy remains the mainstay for attenuation of PD symptoms. Nonetheless, the potential benefit of current pharmacotherapies is mostly limited by adverse side effects, such as drug-induced dyskinesia, motor fluctuations and psychosis. Non-dopaminergic receptors, such as human A2A adenosine receptors, have emerged as important therapeutic targets in potentiating therapeutic effects and reducing the unwanted side effects. In this study, new chemical entities targeting both human A2A adenosine receptor and dopamine D2 receptor were designed and evaluated. Two computational methods, namely support vector machine (SVM) models and Tanimoto similarity-based clustering analysis, were integrated for the identification of compounds containing indole-piperazine-pyrimidine (IPP) scaffold. Subsequent synthesis and testing resulted in compounds 5 and 6, which acted as human A2A adenosine receptor binders in the radioligand competition assay (Ki = 8.7-11.2 µM) as well as human dopamine D2 receptor binders in the artificial cell membrane assay (EC50 = 22.5-40.2 µM). Moreover, compound 5 showed improvement in movement and mitigation of the loss of dopaminergic neurons in Drosophila models of PD. Furthermore, in vitro toxicity studies on compounds 5 and 6 did not reveal any mutagenicity (up to 100 µM), hepatotoxicity (up to 30 µM) or cardiotoxicity (up to 30 µM).

[In vitro pharmacodynamics study of an anti-HIV Chinese herbal formulation].

AIDS caused by HIV-1, is a major threat to human being. An anti-HIV formulation from Chinese herbs, so called "Qu Du Zeng Ning", have been recently developed. In this work, the pharmacodynamics of the formulation in vitro was studied. The results showed that Qu Du Zeng Ning inhibit the replication of HIV-1 efficiently in all cell-based assay, with IC50 at 105.2, 70.7, 77.4 microg mL(-1), separately. A significant synergy between the formulation and zidovudine (AZT) was observed, and it also showed a potent activity against HIV-1 drug-resistant mutant.

Screening for HIV protease inhibitors by protection against activity-mediated cytotoxicity in Escherichia coli.

Expressed retroviral proteases are often cytotoxic to the hosts. The cytotoxicity of a tethered dimer HIV protease described previously is particularly severe that transformed Escherichia coli cells could not survive the bactericidal activity of the low-level protease produced under uninduced conditions. The presence of HIV protease inhibitors protected the transformed cells from cytotoxic effects and allowed the growth of these cells on plates and in broth. A high throughput screening method was developed to seek compounds that served as "growth factors" for the HIV protease restricted cells. Several compounds identified by this screening supported the growth of these cells, preserved their viability, and inhibited HIV protease. This assay could be used as a general method for screening for inhibitors of recombinant enzymes that produce a cytotoxic phenotype in host cells.