Eine niedermolekulare Verbindung inhibiert die Proteindisulfidisomerase und sensibilisiert Krebszellen für die Chemotherapie

Discovery and Mechanistic Elucidation of a Class of Protein Disulfide Isomerase Inhibitors for the Treatment of Glioblastoma

Protein disulfide isomerase (PDI) is overexpressed in glioblastoma, the most aggressive form of brain cancer, and folds nascent proteins responsible for the progression and spread of the disease. Herein we describe a novel nanomolar PDI inhibitor, pyrimidotriazinedione 35G8, that is toxic in a panel of human glioblastoma cell lines. We performed a medium-throughput 20 000-compound screen of a diverse subset of 1 000 000 compounds to identify cytotoxic small molecules. Cytotoxic compounds were screened for PDI inhibition, and, from the screen, 35G8 emerged as the most cytotoxic inhibitor of PDI. Bromouridine labeling and sequencing (Bru-seq) of nascent RNA revealed that 35G8 induces nuclear factor-like 2 (Nrf2) antioxidant response, endoplasmic reticulum (ER) stress response, and autophagy. Specifically, 35G8 upregulated heme oxygenase 1 and solute carrier family 7 member 11 (SLC7A11) transcription and protein expression and repressed PDI target genes such as thioredoxin-interacting protein 1 (TXNIP) and early growth response 1 (EGR1). Interestingly, 35G8-induced cell death did not proceed via apoptosis or necrosis, but by a mixture of autophagy and ferroptosis. Cumulatively, our data demonstrate a mechanism for a novel PDI inhibitor as a chemical probe to validate PDI as a target for brain cancer.

Parameterization of the Hamiltonian Dielectric Solvent (HADES) Reaction-Field Method for the Solvation Free Energies of Amino Acid Side-Chain Analogs

Optimization of the Hamiltonian dielectric solvent (HADES) method for biomolecular simulations in a dielectric continuum is presented with the goal of calculating accurate absolute solvation free energies while retaining the model's accuracy in predicting conformational free-energy differences. The solvation free energies of neutral and polar amino acid side-chain analogs calculated by using HADES, which may optionally include nonpolar contributions, were optimized against experimental data to reach a chemical accuracy of about 0.5 kcal mol(-1). The new parameters were evaluated for charged side-chain analogs. The HADES results were compared with explicit-solvent, generalized Born, Poisson-Boltzmann, and QM-based methods. The potentials of mean force (PMFs) between pairs of side-chain analogs obtained by using HADES and explicit-solvent simulations were used to evaluate the effects of the improved parameters optimized for solvation free energies on intermolecular potentials.