The Evaluation of L-Tryptophan Derivatives as Inhibitors of the LType Amino Acid Transporter LAT1 (SLC7A5)

Study on dissociated states of twenty proteinogenic amino acids and their interactions with LAT1 by HPCE-IICRD

High performance capillary electrophoresis (HPCE) has been widely applied in the analysis of amino acids (AAs), but no studies on the HPCE analysis of dissociated states of AAs have been reported. Here, twenty proteingenic AAs were analyzed by the newly-developed universal interface-induced current detector (IICRD). Two or three current signal peaks were observed in current electrophoretograms (CR-EGs), while only one peak with low sensitivity can be obtained by DAD. The current signal peaks of AAs were accurately identified by adding charge-neutral marker, comparing current signal peaks at different pH conditions, also calculating by pKa. The qualitative analysis indicated that the three current signal peaks of basic AAs were monovalent cations ([AA+]), charge-neutral forms ([AA±]), and monovalent anions ([AA-]) in order. Similarly, acidic AAs can be detected in three forms as [AA±], [AA-] and [AA2-], while neutral AAs can be detected as [AA±] and [AA-]. Quantitative analysis showed that HPCE-IICRD can enhance the sensitivity of AAs to 40 μmol/L in LOD, with a linear range from 10-6 mol/L to 10-2 mol/L. Furthermore, interactions between different dissociated states of twenty AAs and l-type amino acid transporter (LAT1) were studied by combined application of NICCE method for the first time. The binding kinetic parameters and mole number of LAT1 on cell membranes can also be obtained. Besides, competitive binding experiments proved that JPH203 (LAT1-specific inhibitor) and leucine shared the same binding site. HPCE-IICRD provides a new method to reveal the interaction between different dissociated forms of AAs or other biomolecules and essential receptors.

Discovery of New Nanomolar Selective IRAP Inhibitors

Among the M1 family of oxytocinase aminopeptidases, insulin-regulated aminopeptidase IRAP, is an emerging drug target implicated in various biological pathways and particularly in MHC-I antigen presentation through amino-terminal trimming of exogenous cross-presented peptides. A few series of inhibitors inspired either by angiotensin IV, one of IRAP substrates, or by bestatin a pan aminopeptidase inhibitor, have been disclosed. However, the variety and number of chemotypes remains relatively limited. Here we disclose the design and optimization of a series of hydroxamic acids IRAP inhibitors bearing a 5-substituted indole. Docking studies of the best compound 43 (BDM_92499), a single-digit nanomolar and selective inhibitor of IRAP, suggest an original binding mode and highlight the substituent on the indole and a primary amide as groups driving selectivity. Several inhibitors in the series displayed IRAP-dependent inhibition of antigen cross-presentation. These results pave the way to the development of novel therapeutic agents targeting IRAP.

One-Step Synthesis for Orn-Val with High Molecular Weight and Low Polydispersity by Ugi Four-Component Condensation

Basic amino acid alternating copolymers exhibit exceptional antimicrobial properties and biosafety, yet their application is restricted by the complexity of the synthesis process and low molecular weight (Mn = 1000). In this study, we synthesized a basic amino acid alternating copolymer (Orn-Val) in only one step by the Ugi four-component condensation (Ugi'4CC), achieving high molecular weight (Mn = 20,000) and narrow polydispersity (PDI ≤ 1.10). Furthermore, we observed that factors such as the feed ratio, reaction solvent, and pH significantly influenced the molecular weight and polydispersity of MPE-Orn-Val-Cbz. Moreover, the structure of potassium isocyanate also significantly affected the molecular weight and polydispersity of the products. And it was also demonstrated that the obtained Orn-Val demonstrated excellent antimicrobial properties and biocompatibility. Therefore, this method effectively addresses the limitations associated with the complex synthesis process and low molecular weight of amino acid alternating copolymers.

A Review on the Role of Human Solute Carriers Transporters in Cancer

Background and Aim

The high rate of tumor growth results in an increased need for amino acids. As solute carriers (SLC) transporters are capable of transporting different amino acids, cancer may develop as a result of these transporters' over-expression due to their complex formation with other biological molecules. Therefore, this review investigated the role of SLC transporters in the progression of cancer.

Methods

We retrieved data from Google Scholar, Web of Science, PubMed, Cochrane Library, and EMBASE regarding the influence of human SLCs on the development of cancer. Articles published in English before August 2024 were included in the study.

Results

The overexpression of SLCs is strongly related to tumor cell proliferation and angiogenesis in a number of cancer types including thyroid, pancreatic, lung, hepatocellular, and colon cancers. They are crucial for the stimulation of several biological signaling pathways, particularly mTOR kinase activity, which starts a signaling cascade, protein synthesis, cell growth, and proliferation, and inhibits apoptosis of cancerous cells. Furthermore, they contribute to the activation of PI3K/AKT signaling, which has an impact on the growth, invasion, and death of cancer cells. Thus, SLC transporters become a potential therapeutic target that plays a crucial role in drug resistance, tumor microenvironment regulation, and modulation of immune response.

Conclusion

The review recognized the crucial role of SLC transporters in different types of cancer progression. Therefore, to confirm our findings, a case-control study is required to investigate the role of amino acid transporters in cancer development.

Pathobiochemistry of Aging and Neurodegeneration: Deregulation of NAD+ Metabolism in Brain Cells

NAD+ plays a pivotal role in energy metabolism and adaptation to external stimuli and stressful conditions. A significant reduction in intracellular NAD+ levels is associated with aging and contributes to the development of chronic cardiovascular, neurodegenerative, and metabolic diseases. It is of particular importance to maintain optimal levels of NAD+ in cells with high energy consumption, particularly in the brain. Maintaining the tissue level of NAD+ with pharmacological tools has the potential to slow down the aging process, to prevent the development of age-related diseases. This review covers key aspects of NAD+ metabolism in terms of brain metabolic plasticity, including NAD+ biosynthesis and degradation in different types of brain cells, as well as its contribution to the development of neurodegeneration and aging, and highlights up-to-date approaches to modulate NAD+ levels in brain cells.

Design strategies and recent development of bioactive modulators for glutamine transporters

Glutamine transporters are integral to the metabolism of glutamine in both healthy tissues and cancerous cells, playing a pivotal role in maintaining amino acid balance, synthesizing biomolecules, and regulating redox equilibrium. Their critical functions in cellular metabolism make them promising targets for oncological therapies. Recent years have witnessed substantial progress in the field of glutamine transporters, marked by breakthroughs in understanding of their protein structures and the discovery of novel inhibitors, prodrugs, and radiotracers. This review provides a comprehensive update on the latest advancements in modulators targeting the glutamine transporter, with special attention given to LAT1 and ASCT2. It also discusses innovative approaches in drug design aimed at these transporters.

Exploring Amino Acid Transporters as Therapeutic Targets for Cancer: An Examination of Inhibitor Structures, Selectivity Issues, and Discovery Approaches

Amino acid transporters are abundant amongst the solute carrier family and have an important role in facilitating the transfer of amino acids across cell membranes. Because of their impact on cell nutrient distribution, they also appear to have an important role in the growth and development of cancer. Naturally, this has made amino acid transporters a novel target of interest for the development of new anticancer drugs. Many attempts have been made to develop inhibitors of amino acid transporters to slow down cancer cell growth, and some have even reached clinical trials. The purpose of this review is to help organize the available information on the efforts to discover amino acid transporter inhibitors by focusing on the amino acid transporters ASCT2 (SLC1A5), LAT1 (SLC7A5), xCT (SLC7A11), SNAT1 (SLC38A1), SNAT2 (SLC38A2), and PAT1 (SLC36A1). We discuss the function of the transporters, their implication in cancer, their known inhibitors, issues regarding selective inhibitors, and the efforts and strategies of discovering inhibitors. The goal is to encourage researchers to continue the search and development within the field of cancer treatment research targeting amino acid transporters.

Describing inhibitor specificity for the amino acid transporter LAT1 from metainference simulations

The human L-type amino acid transporter 1 (LAT1; SLC7A5) is a membrane transporter of amino acids, thyroid hormones, and drugs such as the Parkinson's disease drug levodopa (L-Dopa). LAT1 is found in the blood-brain barrier, testis, bone marrow, and placenta, and its dysregulation has been associated with various neurological diseases, such as autism and epilepsy, as well as cancer. In this study, we combine metainference molecular dynamics simulations, molecular docking, and experimental testing, to characterize LAT1-inhibitor interactions. We first conducted a series of molecular docking experiments to identify the most relevant interactions between LAT1's substrate-binding site and ligands, including both inhibitors and substrates. We then performed metainference molecular dynamics simulations using cryoelectron microscopy structures in different conformations of LAT1 with the electron density map as a spatial restraint, to explore the inherent heterogeneity in the structures. We analyzed the LAT1 substrate-binding site to map important LAT1-ligand interactions as well as newly described druggable pockets. Finally, this analysis guided the discovery of previously unknown LAT1 ligands using virtual screening and cellular uptake experiments. Our results improve our understanding of LAT1-inhibitor recognition, providing a framework for rational design of future lead compounds targeting this key drug target.

Recent progress of amino acid transporters as a novel antitumor target

Glutamine transporters transport different amino acids for cell growth and metabolism. In tumor cells, glutamine transporters are often highly expressed and play a crucial role in their growth. By inhibiting the amino acid transport of these transporters, the growth of cancer cells can be inhibited. In recent years, more and more attention has been paid to the study of glutamine transporter. In this article, the differences between the ASC system amino acid transporter 2 (ASCT2), L-type amino acid transporter 1 (LAT1), and the cystine–glutamate exchange (xCT) transporters research progress on the mechanism of action and corresponding small molecule inhibitors are summarized. This article introduces 62 related small molecule inhibitors of different transporters of ASCT2, LAT1, and xCT. These novel chemical structures provide ideas for the research and design of targeted inhibitors of glutamine transporters, as well as important references and clues for the design of new anti-tumor drugs.