Structural Achievability of an NH-π Interaction between Gln and Phe in a Crystal Structure of a Collagen-like Peptide

Advances in nanotechnology-based approaches for the treatment of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC), one of the most common types of cancers occurring in the head and neck region, is often associated with high mortality rates due to its invasiveness and morbidity. The mainstream treatment methods in clinical settings, including surgery, chemotherapy, and radiotherapy, may cause poor overall survival rate and prognosis, with issues such as drug resistance, damage to adjacent healthy tissues, and potential recurrences. Other treatment approaches such as immunotherapy, photodynamic therapy (PDT), and photothermal therapy (PPT) also suffer from inefficient tumor targeting and suboptimal therapeutic outcomes. Early detection is vital for HNSCC patients, but it is always limited by insensitivity and confusing clinical manifestations. Hence, it is highly desirable to develop optimized therapeutic and diagnostic strategies. With the boom in nanomaterials, nanotechnology-conducted HNSCC therapy has attracted widespread attention. Nanoparticles (NPs) are distinguished by their unique morphology and superior physicochemical property, and some can exhibit direct antitumor activity, while others serve as promising candidates for drug delivery. In addition, NPs offer the potential for structural modification for drug delivery and tumor targeting, enabling specific delivery to tumor cells through conjugation with biomarker ligands and improving cargo biocompatibility. This work reviews current therapies and diagnosis methods for HNSCC, highlights the characteristics of the major NPs, surveys their uses and advantages in the treatment of HNSCC, and discusses the obstacles and prospects in clinical applications, aiming to enlighten future research directions for nanotechnology-based therapy for HNSCC.

Stabilization of the retromer complex: Analysis of novel binding sites of bis-1,3-phenyl guanylhydrazone 2a to the VPS29/VPS35 interface

The stabilization of the retromer protein complex can be effective in the treatment of different neurological disorders. Following the identification of bis-1,3-phenyl guanylhydrazone 2a as an effective new compound for the treatment of amyotrophic lateral sclerosis, in this work we analyze the possible binding sites of this molecule to the VPS35/VPS29 dimer of the retromer complex. Our results show that the affinity for different sites of the protein assembly depends on compound charge and therefore slight changes in the cell microenvironment could promote different binding states. Finally, we describe a novel binding site located in a deep cleft between VPS29 and VPS35 that should be further explored to select novel molecular chaperones for the stabilization of the retromer complex.

Adaptation strategies of giant viruses to low-temperature marine ecosystems

Microbes in marine ecosystems have evolved their gene content to thrive successfully in the cold. Although this process has been reasonably well studied in bacteria and selected eukaryotes, less is known about the impact of cold environments on the genomes of viruses that infect eukaryotes. Here, we analyzed cold adaptations in giant viruses (Nucleocytoviricota and Mirusviricota) from austral marine environments and compared them with their Arctic and temperate counterparts. We recovered giant virus metagenome-assembled genomes (98 Nucleocytoviricota and 12 Mirusviricota MAGs) from 61 newly sequenced metagenomes and metaviromes from sub-Antarctic Patagonian fjords and Antarctic seawater samples. When analyzing our data set alongside Antarctic and Arctic giant viruses MAGs already deposited in the Global Ocean Eukaryotic Viral database, we found that Antarctic and Arctic giant viruses predominantly inhabit sub-10°C environments, featuring a high proportion of unique phylotypes in each ecosystem. In contrast, giant viruses in Patagonian fjords were subject to broader temperature ranges and showed a lower degree of endemicity. However, despite differences in their distribution, giant viruses inhabiting low-temperature marine ecosystems evolved genomic cold-adaptation strategies that led to changes in genetic functions and amino acid frequencies that ultimately affect both gene content and protein structure. Such changes seem to be absent in their mesophilic counterparts. The uniqueness of these cold-adapted marine giant viruses may now be threatened by climate change, leading to a potential reduction in their biodiversity.

Enhanced anti-tumor activity of arginine decarboxylase through the incorporation of aromatic amino acids at the multimer-forming interface

The pressing challenge of cancer's high mortality and invasiveness demands improved therapeutic approaches. Targeting the nutrient dependencies within cancer cells has emerged as a promising approach. This study is dedicated to demonstrating the potential of arginine depletion for cancer treatment. Notably, the focus centers on arginine decarboxylase (RDC), a pH-dependent enzyme expecting enhanced activity within the slightly acidic microenvironments of tumors. To investigate the effect of a single-site mutation on the catalytic efficacy of RDC, diverse amino acids, including glycine, alanine, phenylalanine, tyrosine, tryptophan, p-azido-phenylalanine, and a phenylalanine analog with a hydrogen-substituted tetrazine, were introduced at the crucial threonine site (position 39) in the multimer-forming interface. Remarkably, the introduction of either a natural or a non-natural aromatic amino acid at position 39 substantially boosted enzymatic activity, while amino acids with smaller side chains did not show the same effect. This enhanced enzymatic activity is likely attributed to the reinforced formation of multimer structures through favorable interactions between the introduced aromatic amino acid and the neighboring subunit. Noteworthy, at slightly acidic pH, the RDC variant featuring tryptophan at position 39 demonstrated augmented cytotoxicity against tumor cells compared to the wild-type RDC. This attribute aligns with the tumor microenvironment and positions these variants as potential candidates for targeted cancer therapy.

Low entropic cost of binding confers high selectivity on an allosteric ERK2 inhibitor

Extracellular signal-regulated kinase 2 (ERK2), a mitogen-activated protein kinase (MAPK), plays an essential role in physiological cellular processes and is a drug target for treating cancers and type 2 diabetes. A previous in silico screening study focusing on an allosteric site that plays a crucial role in substrate anchoring conferred an ERK2 inhibitor (compound 1). In this report, compound 1 was found to show high selectivity toward ERK2 compared with the nearest off-target p38α MAPK, and the crystal structure revealed that compound 1 binds to the allosteric site of ERK2. Fragment molecular orbital calculations based upon this crystal structure provided the structural basis to improve potency of compound 1 derivatives. Further computational studies uncovered that the low entropic cost of binding conferred the high selectivity of compound 1 toward ERK2 over p38α MAPK. These findings demonstrate the feasibility of developing potent and selective ERK2 inhibitors.