Development of a Flexible and Robust Synthesis of Tetrahydrofuro[3,4-b]furan Nucleoside Analogues

Is it still worth renewing nucleoside anticancer drugs nowadays?

Nucleoside has situated the convergence point in the discovery of novel drugs for decades, and a large number of nucleoside derivatives have been constructed for screening novel pharmacological properties at various experimental platforms. Notably, nearly 20 nucleosides are approved to be used in the clinic treatment of various cancers. Nevertheless, the blossom of synthetic nucleoside analogs in comparison with the scarcity of nucleoside anticancer drugs leads to a question: Is it still worth insisting on the screening of novel anticancer drugs from nucleoside derivatives? Hence, this review attempts to emphasize the importance of nucleoside analogs in the discovery of novel anticancer drugs. Firstly, we introduce the metabolic procedures of nucleoside anticancer drug (such as 5-fluorouracil) and summarize the designing of novel nucleoside anticancer candidates based on clinically used nucleoside anticancer drugs (such as gemcitabine). Furthermore, we collect anticancer properties of some recently synthesized nucleoside analogs, aiming at emphasizing the availability of nucleoside analogs in the discovery of anticancer drugs. Finally, a variety of synthetic strategies including the linkage of sugar moiety with nucleobase scaffold, modifications on the sugar moiety, and variations on the nucleobase structure are collected to exhibit the abundant protocols in the achievement of nucleoside analogs. Taken the above discussions collectively, nucleoside still advantages for the finding of novel anticancer drugs because of the clearly metabolic procedures, successfully clinic applications, and abundantly synthetic routines.

Carbohydrate-Templated Syntheses of Trifluoromethyl-Substituted MEP Analogues for the Study of the Methylerythritol Phosphate Pathway

Trifluoromethyl analogues of methylerythritol phosphate (MEP) and 2-C-methyl-erythritol 2,4-cyclodiphosphate (MEcPP), natural substrates of key enzymes from the MEP pathway, were prepared starting from d-glucose as the chiral template to secure absolute configurations. The obligate trifluoromethyl group was inserted with complete diastereoselectivity using the Ruppert-Prakash nucleophile. Target compounds were assayed against the corresponding enzymes showing that trifluoro-MEP did not disrupt IspD activity, whereas trifluoro-MEcPP induced 40% inhibition of IspG at 1 mM.

Targeting Arginine Methyltransferase PRMT5 for Cancer Therapy: Updated Progress and Novel Strategies

As a predominant type II protein arginine methyltransferase, PRMT5 plays critical roles in various normal cellular processes by catalyzing the mono- and symmetrical dimethylation of a wide range of histone and nonhistone substrates. Clinical studies have revealed that high expression of PRMT5 is observed in different solid tumors and hematological malignancies and is closely associated with cancer initiation and progression. Accordingly, PRMT5 is becoming a promising anticancer target and has received great attention in both the pharmaceutical industry and the academic community. In this Perspective, we comprehensively summarize recent advances in the development of first-generation PRMT5 enzymatic inhibitors and highlight novel strategies targeting PRMT5 in the past 5 years. We also discuss the challenges and opportunities of PRMT5 inhibition, with the aim of shedding light on future PRMT5 drug discovery.

The Structural Effects of Phosphorylation of Protein Arginine Methyltransferase 5 on Its Binding to Histone H4

The protein arginine methyltransferase 5 (PRMT5) enzyme is responsible for arginine methylation on various proteins, including histone H4. PRMT5 is a promising drug target, playing a role in the pathomechanism of several diseases, especially in the progression of certain types of cancer. It was recently proved that the phosphorylation of PRMT5 on T80 residue increases its methyltransferase activity; furthermore, elevated levels of the enzyme were measured in the case of human hepatocellular carcinoma and other types of tumours. In this study, we constructed the complexes of the unmodified human PRMT5-methylosome protein 50 (MEP50) structure and its T80-phosphorylated variant in complex with the full-length histone H4 peptide. The full-length histone H4 was built in situ into the human PRMT5-MEP50 enzyme using experimental H4 fragments. Extensive molecular dynamic simulations and structure and energy analyses were performed for the complexed and apo protein partners, as well. Our results provided an atomic level explanation for two important experimental findings: (1) the increased methyltransferase activity of the phosphorylated PRMT5 when compared to the unmodified type; (2) the PRMT5 methylates only the free form of histone H4 not bound in the nucleosome. The atomic level complex structure H4-PRMT5-MEP50 will help the design of new inhibitors and in uncovering further structure–function relationships of PRMT enzymes.

Design and synthesis of unprecedented 9- and 10-membered cyclonucleosides with PRMT5 inhibitory activity

Synthesis of medium-sized rings is known to be challenging due to high transannular strain especially for 9- and 10-membered rings. Herein we report design and synthesis of unprecedented 9- and 10-membered purine 8,5'-cyclonucleosides as the first cyclonucleoside PRMT5 inhibitors. The cocrystal structure of PRMT5:MEP50 in complex with the synthesized 9-membered cyclonucleoside 1 revealed its binding mode in the SAM binding pocket of PRMT5.