The recent advance and prospect of poly(ADP-ribose) polymerase inhibitors for the treatment of cancer.

Chemotherapies are commonly used in cancer therapy, their applications are limited to low specificity, severe adverse reactions, and long-term medication-induced drug resistance. Poly(ADP-ribose) polymerase (PARP) inhibitors are a novel class of antitumor drugs developed to solve these intractable problems based on the mechanism of DNA damage repair, which have been widely applied in the treatment of ovarian cancer, breast cancer, and other cancers through inducing synthetic lethal effect and trapping PARP-DNA complex in BRCA gene mutated cancer cells. In recent years, PARP inhibitors have been widely used in combination with various first-line chemotherapy drugs, targeted drugs and immune checkpoint inhibitors to expand the scope of clinical application. However, the intricate mechanisms underlying the drug resistance to PARP inhibitors, including the restoration of homologous recombination, stabilization of DNA replication forks, overexpression of drug efflux protein, and epigenetic modifications pose great challenges and desirability in the development of novel PARP inhibitors. In this review, we will focus on the mechanism, structure-activity relationship, and multidrug resistance associated with the representative PARP inhibitors. Furthermore, we aim to provide insights into the development prospects and emerging trends to offer guidance for the clinical application and inspiration for the development of novel PARP inhibitors and degraders.

A comprehensive review of new small molecule drugs approved by the FDA in 2022: Advance and prospect.

In 2022, the U.S. Food and Drug Administration approved a total of 16 marketing applications for small molecule drugs, which not only provided dominant scaffolds but also introduced novel mechanisms of action and clinical indications. The successful cases provide valuable information for optimizing efficacy and enhancing pharmacokinetic properties through strategies like macrocyclization, bioequivalent group utilization, prodrug synthesis, and conformation restriction. Therefore, gaining an in-depth understanding of the design principles and strategies underlying these drugs will greatly facilitate the development of new therapeutic agents. This review focuses on the research and development process of these newly approved small molecule drugs including drug design, structural modification, and improvement of pharmacokinetic properties to inspire future research in this field.

Discovery of 1,2,4-Triazole-3-thione Derivatives as Potent and Selective DCN1 Inhibitors for Pathological Cardiac Fibrosis and Remodeling.

DCN1, a critical co-E3 ligase during the neddylation process, is overactivated in many diseases, such as cancers, heart failure as well as fibrotic diseases, and has been regarded as a new target for drug development. Herein, we designed and synthesized a new class of 1,2,4-triazole-3-thione-based DCN1 inhibitors based the hit HD1 identified from high-throughput screening and optimized through numerous structure-activity-relationship (SAR) explorations. HD2 (IC50= 2.96 nM) was finally identified and represented a highly potent and selective DCN1 inhibitor with favorable PK properties and low toxicity. Amazingly, HD2 effectively relieved Ang II/TGFß-induced cardiac fibroblast activation in vitro, and reduced ISO-induced cardiac fibrosis as well as remodeling in vivo, which was linked to the inhibition of cullin 3 neddylation and its substrate Nrf2 accumulation. Our findings unveil a novel 1,2,4-triazole-3-thione-based derivative HD2, which can be recognized as a promising lead compound targeting DCN1 for cardiac fibrosis and remodeling.

Discovery of novel pyrazolo[1,5-a]pyrimidine derivatives as potent reversal agents against ABCB1-mediated multidrug resistance.

The P-glycoprotein (ABCB1)-mediated multidrug resistance (MDR) has emerged as a significant impediment to the efficacy of cancer chemotherapy in clinical therapy, which could promote the development of effective agents for MDR reversal. In this work, we reported the exploration of novel pyrazolo [1,5-a]pyrimidine derivatives as potent reversal agents capable of enhancing the sensitivity of ABCB1-mediated MDR MCF-7/ADR cells to paclitaxel (PTX). Among them, compound 16q remarkably increased the sensitivity of MCF-7/ADR cells to PTX at 5 µM (IC50 = 27.00 nM, RF = 247.40) and 10 µM (IC50 = 10.07 nM, RF = 663.44). Compound 16q could effectively bind and stabilize ABCB1, and does not affect the expression and subcellular localization of ABCB1 in MCF-7/ADR cells. Compound 16q inhibited the function of ABCB1, thereby increasing PTX accumulation, and interrupting the accumulation and efflux of the ABCB1-mediated Rh123, thus resulting in exhibiting good reversal effects. In addition, due to the potent reversal effects of compound 16q, the abilities of PTX to inhibit tubulin depolymerization, and induce cell cycle arrest and apoptosis in MCF-7/ADR cells under low-dose conditions were restored. These results indicate that compound 16q might be a promising potent reversal agent capable of revising ABCB1-mediated MDR, and pyrazolo [1,5-a]pyrimidine might represent a novel scaffold for the discovery of new ABCB1-mediated MDR reversal agents.

Histone deacetylase complexes: Structure, regulation and function.

Histone deacetylases (HDACs) are key epigenetic regulators, and transcriptional complexes with deacetylase function are among the epigenetic corepressor complexes in the nucleus that target the epigenome. HDAC-bearing corepressor complexes such as the Sin3 complex, NuRD complex, CoREST complex, and SMRT/NCoR complex are common in biological systems. These complexes activate the otherwise inactive HDACs in a solitary state. HDAC complexes play vital roles in the regulation of key biological processes such as transcription, replication, and DNA repair. Moreover, deregulated HDAC complex function is implicated in human diseases including cancer. Therapeutic strategies targeting HDAC complexes are being sought actively. Thus, illustration of the nature and composition of HDAC complexes is vital to understanding the molecular basis of their functions under physiologic and pathologic conditions, and for designing targeted therapies. This review presents key aspects of large multiprotein HDAC-bearing complexes including their structure, function, regulatory mechanisms, implication in disease development, and role in therapeutics.

A comprehensive review of small molecule drugs approved by the FDA in 2023: Advances and prospects.

In 2023, the U.S. Food and Drug Administration has approved 55 novel medications, consisting of 17 biologics license applications and 38 new molecular entities. Although the biologics license applications including antibody and enzyme replacement therapy set a historical record, the new molecular entities comprising small molecule drugs, diagnostic agent, RNA interference therapy and biomacromolecular peptide still account for over 50 % of the newly approved medications. The novel and privileged scaffolds derived from drugs, active molecules and natural products are consistently associated with the discovery of new mechanisms, the expansion of clinical indications and the reduction of side effects. Moreover, the structural modifications based on the promising scaffolds can provide the clinical candidates with the improved biological activities, bypass the patent protection and greatly shorten the period of new drug discovery. Therefore, conducting an appraisal of drug approval experience and related information will expedite the identification of more potent drug molecules. In this review, we comprehensively summarized the pertinent information encompassing the clinical application, mechanism, elegant design and development processes of 28 small molecule drugs, and expected to provide the promising structural basis and design inspiration for pharmaceutical chemists.

Decoding CLU (Clusterin): Conquering cancer treatment resistance and immunological barriers.

One major obstacle in the treatment of cancer is the presence of proteins resistant to cancer therapy, which can impede the effectiveness of traditional approaches such as radiation and chemotherapy. This resistance can lead to disease progression and cause treatment failure. Extensive research is currently focused on studying these proteins to create tailored treatments that can circumvent resistance mechanisms. CLU (Clusterin), a chaperone protein, has gained notoriety for its role in promoting resistance to a wide range of cancer treatments, including chemotherapy, radiation therapy, and targeted therapy. The protein has also been discovered to have a role in regulating the immunosuppressive environment within tumors. Its ability to influence oncogenic signaling and inhibit cell death bolster cancer cells resistant against treatments, which poses a significant challenge in the field of oncology. Researchers are actively investigating to the mechanisms by which CLU exerts its resistance-promoting effects, with the ultimate goal of developing strategies to circumvent its impact and enhance the effectiveness of cancer therapies. By exploring CLU's impact on cancer, resistance mechanisms, tumor microenvironment (TME), and therapeutic strategies, this review aims to contribute to the ongoing efforts to improve cancer treatment outcomes.

Mass spectrometry-based pseudotargeted metabolomics reveals metabolic variations in a2-induced gastric cancer cell.

Gastric cancer (GC) is one of the most malignant tumors with high morbidity and mortality in the world. Compound a2, a Jiyuan oridonin derivative, exhibited excellent anti-proliferative activity against GC cells. To investigate the gastric cellular response to a2 therapy as a novel drug candidate, we adopted a pseudotargeted metabolomics method to explore metabolic variation in a2-induced MGC-803 gastric cells using liquid chromatography tandem mass spectrometry combined with multivariate statistical analysis. The results showed that a2 treatment induced significant metabolic changes in the levels of aminoacyl-tRNA biosynthesis, alanine, aspartate and glutamate metabolism, pyrimidine metabolism, and tricarboxylic acid cycle, approximately 80% of the metabolites were down-regulated in the low-dose and high-dose groups including aspartate, tryptophan, sedoheptulose 7-phosphate, succinate, 2'-deoxyadenosine, uridine, cytidine, etc. which can provide evidence for a new therapy of GC.

CD155 as an emerging target in tumor immunotherapy.

CD155 is an immunoglobulin-like protein overexpressed in almost all the tumor cells, which not only promotes proliferation, adhesion, invasion, and migration of tumor cells, but also regulates immune responses by interacting with TIGIT, CD226 or CD96 receptors expressed on several immune cells, thereby modulating the functionality of these cellular subsets. As a novel immune checkpoint, the inhibition of CD155/TIGIT, either as a standalone treatment or in conjunction with other immune checkpoint inhibitors, has demonstrated efficacy in managing advanced solid malignancies. In this review, we summarize the intricate relationship between on tumor surface CD155 and its receptors, with further discussion on how they regulate the occurrence of tumor immune escape. In addition, novel therapeutic strategies and clinical trials targeting CD155 and its receptors are summarized, providing a strong rationale and way forward for the development of next-generation immunotherapies.

USP7 as an emerging therapeutic target: A key regulator of protein homeostasis.

Maintaining protein balance within a cell is essential for proper cellular function, and disruptions in the ubiquitin-proteasome pathway, which is responsible for degrading and recycling unnecessary or damaged proteins, can lead to various diseases. Deubiquitinating enzymes play a vital role in regulating protein homeostasis by removing ubiquitin chains from substrate proteins, thereby controlling important cellular processes, such as apoptosis and DNA repair. Among these enzymes, ubiquitin-specific protease 7 (USP7) is of particular interest. USP7 is a cysteine protease consisting of a TRAF region, catalytic region, and C-terminal ubiquitin-like (UBL) region, and it interacts with tumor suppressors, transcription factors, and other key proteins involved in cell cycle regulation and epigenetic control. Moreover, USP7 has been implicated in the pathogenesis and progression of various diseases, including cancer, inflammation, neurodegenerative conditions, and viral infections. Overall, characterizing the functions of USP7 is crucial for understanding the pathophysiology of diverse diseases and devising innovative therapeutic strategies. This article reviews the structure and function of USP7 and its complexes, its association with diseases, and its known inhibitors and thus represents a valuable resource for advancing USP7 inhibitor development and promoting potential future treatment options for a wide range of diseases.

Combination Therapy and Dual-Target Inhibitors Based on LSD1: New Emerging Tools in Cancer Therapy.

Lysine specific demethylase 1 (LSD1), a transcriptional modulator that represses or activates target gene expression, is overexpressed in many cancer and causes imbalance in the expression of normal gene networks. Over two decades, numerous LSD1 inhibitors have been reported, especially some of which have entered clinical trials, including eight irreversible inhibitors (TCP, ORY-1001, GSK-2879552, INCB059872, IMG-7289, ORY-2001, TAK-418, and LH-1802) and two reversible inhibitors (CC-90011 and SP-2577). Most clinical LSD1 inhibitors demonstrated enhanced efficacy in combination with other agents. LSD1 multitarget inhibitors have also been reported, exampled by clinical dual LSD1/histone deacetylases (HDACs) inhibitors 4SC-202 and JBI-802. Herein, we present a comprehensive overview of the combination of LSD1 inhibitors with various antitumor agents, as well as LSD1 multitarget inhibitors. Additionally, the challenges and future research directionsare also discussed, and we hope this review will provide new insight into the development of LSD1-targeted anticancer agents.

Neddylation-dependent LSD1 destabilization inhibits the stemness and chemoresistance of gastric cancer.

Histone lysine-specific demethylase 1 (LSD1) expression has been evaluated in multiple tumors, including gastric cancer (GC). However, the mechanisms underlying LSD1 dysregulation in GC remain largely unclear. In this study, neural precursor cell-expressed developmentally down-regulated protein 8 (NEDD8) was identified to be conjugated to LSD1 at K63 by ubiquitin-conjugating enzyme E2 M (UBE2M), and this neddylated LSD1 could promote LSD1 ubiquitination and degradation, leading to a decrease of GC cell stemness and chemoresistance. Herein, our findings revealed a novel mechanism of LSD1 neddylation and its contribution to decreasing GC cell stemness and chemoresistance. Taken together, our findings may whistle about the future application of neddylation inhibitors.

LSD1 in drug discovery: From biological function to clinical application.

Lysine-specific demethylase 1 (LSD1) is a flavin adenine dinucleotide (FAD) dependent monoamine oxidase (MAO) that erases the mono-, and dimethylation of histone 3 lysine 4 (H3K4), resulting in the suppression of target gene transcriptions. Besides, it can also demethylate some nonhistone substrates to regulate their biological functions. As reported, LSD1 is widely upregulated and plays a key role in several kinds of cancers, pharmacological or genetic ablation of LSD1 in cancer cells suppresses cell aggressiveness by several distinct mechanisms. Therefore, numerous LSD1 inhibitors, including covalent and noncovalent, have been developed and several of them have entered clinical trials. Herein, we systemically reviewed and discussed the biological function of LSD1 in tumors, lymphocytes as well as LSD1-targeting inhibitors in clinical trials, hoping to benefit the field of LSD1 and its inhibitors.

Targeting cullin neddylation for cancer and fibrotic diseases.

Protein neddylation is a post-translational modification, and its best recognized substrates are cullin family proteins, which are the core component of Cullin-RING ligases (CRLs). Given that most neddylation pathway proteins are overactivated in different cancers and fibrotic diseases, targeting neddylation becomes an emerging approach for the treatment of these diseases. To date, numerous neddylation inhibitors have been developed, of which MLN4924 has entered phase I/II/III clinical trials for cancer treatment, such as acute myeloid leukemia, melanoma, lymphoma and solid tumors. Here, we systematically describe the structures and biological functions of the critical enzymes in neddylation, highlight the medicinal chemistry advances in the development of neddylation inhibitors and propose the perspectives concerning targeting neddylation for cancer and fibrotic diseases.

Discovery of neddylation E2s inhibitors with therapeutic activity.

Neddylation is the writing of monomers or polymers of neural precursor cells expressed developmentally down-regulated 8 (NEDD8) to substrate. For neddylation to occur, three enzymes are required: activators (E1), conjugators (E2), and ligators (E3). However, the central role is played by the ubiquitin-conjugating enzymes E2M (UBE2M) and E2F (UBE2F), which are part of the E2 enzyme family. Recent understanding of the structure and mechanism of these two proteins provides insight into their physiological effects on apoptosis, cell cycle arrest and genome stability. To treat cancer, it is therefore appealing to develop novel inhibitors against UBE2M or UBE2F interactions with either E1 or E3. In this evaluation, we summarized the existing understanding of E2 interaction with E1 and E3 and reviewed the prospective of using neddylation E2 as a pharmacological target for evolving new anti-cancer remedies.

Novel acridine-based LSD1 inhibitors enhance immune response in gastric cancer.

Recently, histone lysine specific demethylase 1 (LSD1) has become an emerging and promising target for cancer immunotherapy. Herein, based on our previously reported LSD1 inhibitor DXJ-1 (also called 6x), a series of novel acridine-based LSD1 inhibitors were identified via structure optimizations. Among them, compound 5ac demonstrated significantly enhanced inhibitory activity against LSD1 with an IC50 value of 13 nM, about 4.6-fold more potent than DXJ-1 (IC50 = 73 nM). Molecular docking studies revealed that compound 5ac could dock well into the active site of LSD1. Further mechanism studies showed that compound 5ac inhibited the stemness and migration of gastric cancer cells, and reduced the expression of PD-L1 in BGC-823 and MFC cells. More importantly, BGC-823 cells were more sensitive to T cell killing when treated with compound 5ac. Besides, the tumor growth was also suppressed by compound 5ac in mice. Together, 5ac could serve as a promising candidate to enhance immune response in gastric cancer.

Micafungin: A promising inhibitor of UBE2M in cancer cell growth suppression.

Neddylation is a protein modification process similar to ubiquitination, carried out through a series of activating (E1), conjugating (E2), and ligating (E3) enzymes. This process has been found to be overactive in various cancers, leading to increased oncogenic activities. Ubiquitin-conjugating enzyme 2 M (UBE2M) is one of two neddylation enzymes that play a vital role in this pathway. Studies have shown that targeting UBE2M in cancer treatment is crucial, as it regulates many molecular mechanisms like DNA damage, apoptosis, and cell proliferation. However, developing small molecule inhibitors against UBE2M remains challenging due to the lack of suitable druggable pockets. We have discovered that Micafungin, an antifungal agent that inhibits the production of 1,3-ß-D-glucan in fungal cell walls, acts as a neddylation inhibitor that targets UBE2M. Biochemical studies reveal that Micafungin obstructs neddylation and stabilizes UBE2M. In cellular experiments, the drug was found to interact with UBE2M, prevent neddylation, accumulate cullin ring ligases (CRLs) substrates, reduce cell survival and migration, and induce DNA damage in gastric cancer cells. This research uncovers a new anti-cancer mechanism for Micafungin, paving the way for the development of a novel class of neddylation inhibitors that target UBE2M.

LSD1: an emerging face in altering the tumor microenvironment and enhancing immune checkpoint therapy.

Dysregulation of various cells in the tumor microenvironment (TME) causes immunosuppressive functions and aggressive tumor growth. In combination with immune checkpoint blockade (ICB), epigenetic modification-targeted drugs are emerging as attractive cancer treatments. Lysine-specific demethylase 1 (LSD1) is a protein that modifies histone and non-histone proteins and is known to influence a wide variety of physiological processes. The dysfunction of LSD1 contributes to poor prognosis, poor patient survival, drug resistance, immunosuppression, etc., making it a potential epigenetic target for cancer therapy. This review examines how LSD1 modulates different cell behavior in TME and emphasizes the potential use of LSD1 inhibitors in combination with ICB therapy for future cancer research studies.

The recent advance of Interleukin-1 receptor associated kinase 4 inhibitors for the treatment of inflammation and related diseases.

The interleukin-1 receptor associated kinase 4 (IRAK-4) is a member of serine-threonine kinase family, which plays an important role in the regulation of interleukin-1 receptors (IL-1R) and Toll-like receptors (TLRs) related signaling pathways. At present, the IRAK-4 mediated inflammation and related signaling pathways contribute to inflammation, which are also responsible for other autoimmune diseases and drug resistance in cancers. Therefore, targeting IRAK-4 to develop single-target, multi-target inhibitors and proteolysis-targeting chimera (PROTAC) degraders is an important direction for the treatment of inflammation and related diseases. Moreover, insight into the mechanism of action and structural optimization of the reported IRAK-4 inhibitors will provide the new direction to enrich the clinical therapies for inflammation and related diseases. In this comprehensive review, we introduced the recent advance of IRAK-4 inhibitors and degraders with regards to structural optimization, mechanism of action and clinical application that would be helpful for the development of more potent chemical entities against IRAK-4.