Advances and prospects of analytic methods for bacterial transglycosylation and inhibitor discovery.

The cell wall is essential for bacteria to maintain structural rigidity and withstand external osmotic pressure. In bacteria, the cell wall is composed of peptidoglycan. Lipid II is the basic unit for constructing highly cross-linked peptidoglycan scaffolds. Transglycosylase (TGase) is the initiating enzyme in peptidoglycan synthesis that catalyzes the ligation of lipid II moieties into repeating GlcNAc-MurNAc polysaccharides, followed by transpeptidation to generate cross-linked structures. In addition to the transglycosylases in the class-A penicillin-binding proteins (aPBPs), SEDS (shape, elongation, division and sporulation) proteins are also present in most bacteria and play vital roles in cell wall renewal, elongation, and division. In this review, we focus on the latest analytical methods including the use of radioactive labeling, gel electrophoresis, mass spectrometry, fluorescence labeling, probing undecaprenyl pyrophosphate, fluorescence anisotropy, ligand-binding-induced tryptophan fluorescence quenching, and surface plasmon resonance to evaluate TGase activity in cell wall formation. This review also covers the discovery of TGase inhibitors as potential antibacterial agents. We hope that this review will give readers a better understanding of the chemistry and basic research for the development of novel antibiotics.

Dual-targeting compounds possessing enhanced anticancer activity via microtubule disruption and histone deacetylase inhibition.

Dual-targeting anticancer agents 4-29 are designed by combining the structural features of purine-type microtubule-disrupting compounds and HDAC inhibitors. A library of the conjugate compounds connected by appropriate linkers was synthesized and found to possess HDACs inhibitory activity and render microtubule fragmentation by activating katanin, a microtubule-severing protein. Among various zinc-binding groups, hydroxamic acid shows the highest inhibitory activity of Class I HDACs, which was also reconfirmed by three-dimensional quantitative structure-activity relationship (3D-QSAR) pharmacophore prediction. The purine-hydroxamate conjugates exhibit enhanced cytotoxicity against MDA-MB231 breast cancer cells, H1975 lung cancer cells, and various clinical isolated non-small-cell lung cancer cells with different epidermal growth factor receptor (EGFR) status. Pyridyl substituents could be used to replace the C2 and N9 phenyl moieties in the purine-type scaffold, which can help to improve the solubility under physiological conditions, thus increasing cytotoxicity. In mice treated with the purine-hydroxamate conjugates, the tumor growth rate was significantly reduced without causing toxic effects. Our study demonstrates the potential of the dual-targeting purine-hydroxamate compounds for cancer monotherapy.

Glutathione determines chronic myeloid leukemia vulnerability to an inhibitor of CMPK and TMPK.

Bcr-Abl transformation leads to chronic myeloid leukemia (CML). The acquirement of T315I mutation causes tyrosine kinase inhibitors (TKI) resistance. This study develops a compound, JMF4073, inhibiting thymidylate (TMP) and cytidylate (CMP) kinases, aiming for a new therapy against TKI-resistant CML. In vitro and in vivo treatment of JMF4073 eliminates WT-Bcr-Abl-32D CML cells. However, T315I-Bcr-Abl-32D cells are less vulnerable to JMF4073. Evidence is presented that ATF4-mediated upregulation of GSH causes T315I-Bcr-Abl-32D cells to be less sensitive to JMF4073. Reducing GSH biosynthesis generates replication stress in T315I-Bcr-Abl-32D cells that require dTTP/dCTP synthesis for survival, thus enabling JMF4073 susceptibility. It further shows that the levels of ATF4 and GSH in several human CML blast-crisis cell lines are inversely correlated with JMF4073 sensitivity, and the combinatory treatment of JMF4073 with GSH reducing agent leads to synthetic lethality in these CML blast-crisis lines. Altogether, the investigation indicates an alternative option in CML therapy.