Mini Reviews in Medicinal Chemistry - Volume 23, Issue 18, 2023

Poly (ADP-ribose) polymerase 1 (PARP1) plays important roles in both DNA repair and transcription, and the interplay of these processes in relation to cellular function and disease states has not been well defined. The tumor-suppressor effects of PARP inhibitors have attracted significant interest in the development of novel cancer therapies. As PARP1 binding motifs may be readily found in promoter elements of DNA repair genes, the expanding role of PARP1 in DNA repair does not have to be independent of transcription. The discovery of ADP-ribose binding modules that bind to various forms of mono- and poly-ADP-ribose has provided important insights into how ADPribosylation regulates different cellular pathways. Among the four distinct PAR-binding modules discovered so far, it is the macrodomain alone that, in addition to possessing binding activity, in some instances, also supports a catalytic activity toward ADP-ribose derivatives. However, the development of PARP inhibitors as chemopotentiating agents has been limited by an increase in observed toxicity, mainly myelosuppression, necessitating dose reduction of the cytotoxic chemotherapeutic agent and the PARP inhibitor. Hence, it presents an opportunity to rationally develop combinations of PARP inhibitors with new classes of DNA repair inhibitors that are on the horizon and classical cytotoxic agents. Clinical trials of PARP inhibitors are investigating various uses of these approaches in cancer. Recent studies on the clinical significance of PARP1 inhibitors are discussed in this review. These recent research advances will inform the selection of patient populations who can benefit from the PARP inhibitor treatment and the development of effective drug combination strategies.

Background: Although diagnosis and treatment of prostate cancer (PCa) have evolved rapidly in recent years, clinically significant molecular biomarkers are still needed to lower the mortality. Circular RNAs (circRNAs) are a poorly characterized component of PCa transcriptome. Recently, since the development of deep RNA sequencing and novel bioinformatic pipelines, emerging evidence suggests circRNAs to have diverse functions in the development and progression of PCa. Thus, we attempt to summarize the current situation and potential development prospects about the role of circRNAs in PCa liquid biopsies. Methods: The role of circRNAs in PCa was summarized by searching the literature related to circRNAs in PubMed in recent years. Results: Deregulation of circRNAs is associated with cell proliferation, apoptosis, cell invasion, migration, as well as metastasis in PCa. Because of the high stability and tissue specificity of circRNAs, with improved detection methodologies, circRNAs may be predictive biomarkers in liquid biopsies. Conclusion: From the perspective of recent research, with the development of high-throughput sequencing and novel bioinformatics tools, knowledge of circRNAs will be further expanded. Improved technologies will make personalized precision medicine less of a paper exercise. It is time to further explore circRNA in liquid biopsies.

Paclitaxel is an anticancer drug first isolated from the bark of the Pacific yew tree. It has been widely used for the treatment of ovarian, breast, uterine and other cancers because of its low toxicity, high efficiency and broad-spectrum anticancer activity, and it is considered to be one of the most successful natural anticancer drugs available. Paclitaxel is a microtubule-targeting drug whose main molecular mechanism is to disrupt microtubule dynamics and induce mitotic arrest and cell death. Despite the many clinical successes of paclitaxel, the extraction of natural paclitaxel from Taxus species has proven to be environmentally unsustainable and economically unviable. As a result, researchers are constantly working to find innovative ways to meet society's need for this drug. Currently, many methods, including artificial cultivation, microbial fermentation, chemical synthesis, and tissue and cell culture, have been explored and developed to obtain paclitaxel. In addition, the poor water solubility of paclitaxel has led to significant limitations in its clinical application. Conventional paclitaxel formulations use Cremophor EL and ethanol to dissolve paclitaxel, which can lead to serious side effects. In recent decades, a series of new nanotechnology-based paclitaxel dosage forms have been developed, including albumin-bound paclitaxel, polymeric micellar paclitaxel, polymer-paclitaxel couples, and liposome-encapsulated paclitaxel. These nanoformulations can significantly reduce the toxicity of paclitaxel and greatly improve its anti-tumor efficiency. This paper reviews the development of the production, dosage form and combination therapy of paclitaxel in recent years and presents an outlook, with the aim of providing a theoretical basis and reference for further research on the production and application of paclitaxel in the future

As a novel bio-targeting antitumor agent, an antibody-drug conjugate (ADC) combines the high selectivity of monoclonal antibody and potent cytotoxicity of drug or payload. It can expand the scope of clinical application of small molecule drugs. Tubulysin and its bio-precursor pretubulysin (PT) are potent tubulin-binding antitumor drugs. Due to the excellent antitumoral, antimetastatic, antiangiogenic, and anti-multidrug resistance properties, Tubulysins or PT is believed to be a promising cancer therapeutic approach. Currently, the modifications of tubulysin are centering on the C-11 acetoxyl and N,O-acetal groups, and numerous promising payloads are identified. There are at least 5 sites to introduce appropriate drug linkers in tubulysin and PT for connecting the antibodies. The possible sites of attachment are located in Mep, Tuv, or Tup parts. Cleavage and non-cleavage linkers are used in these ADCs. The chemical reactions involved in the final conjugation of antibody and linkerpayload (LP) are cysteine, lysine, site-specific, and click chemistry reactions. In this article, the recent development of ADCs with tubulysins as the payloads is reviewed, with the hope of providing a reference and future strategies for developing new ADSs.

Histaminergic, orexinergic, and cannabinoid systems play a role in both physiologic and oncogenic mechanisms in digestive tissues. These three systems are important mediators of tumor transformation, as they are associated with redox alterations, which are key aspects in oncological disorders. The three systems are known to promote alterations in the gastric epithelium through intracellular signaling pathways, such as oxidative phosphorylation, mitochondrial dysfunction, and increased Akt, which might promote tumorigenesis. Histamine promotes cell transformation through redox-mediated alterations in the cell cycle, DNA repair, and immunological response. The increase in histamine and oxidative stress generates angiogenic and metastatic signals through the VEGF receptor and H2R-cAMP-PKA pathway. Immunosuppression in the presence of histamine and ROS is linked to a decrease in dendritic and myeloid cells in gastric tissue. These effects are counteracted by histamine receptor antagonists, such as cimetidine. Regarding orexins, overexpression of the Orexin 1 Receptor (OX1R) induces tumor regression through the activation of MAPK-dependent caspases and src-tyrosine. OX1R agonists are candidates for the treatment of gastric cancer by stimulating apoptosis and adhesive interactions. Lastly, cannabinoid type 2 (CB2) receptor agonists increase ROS, leading to the activation of apoptotic pathways. In contrast, cannabinoid type 1 (CB1) receptor agonists decrease ROS formation and inflammation in gastric tumors exposed to cisplatin. Overall, the repercussion of ROS modulation through these three systems on tumor activity in gastric cancer depends on intracellular and/or nuclear signals associated with proliferation, metastasis, angiogenesis, and cell death. Here, we review the role of these modulatory systems and redox alterations in gastric cancer.

Flavonoids are natural polyphenolic compounds and constitute a major class of plant secondary metabolites. To date, structures of more than 10,000 different flavonoids have been elucidated, and most of them are present in cells and tissues of plant parts. Flavonoids have been reported to exert multiple physiological activities and are also consumed as dietary supplements. Flavonoids have been extensively explored as anticancer, anti-inflammatory, antidiabetic, antirheumatic, antioxidant, antimalarial, neuroprotective, cardioprotective, anti-angiogenic, and antiproliferative agents. Most of the flavonoids are biosynthesized in plants via the phenylpropanoid pathway. However, they are associated with some limitations. Chemical synthesis is an alternative strategy to improve the yield and obtain purified products but is hampered by drawbacks, such as intolerance to stressful lab conditions. Pharmacokinetics is the rate-limiting step defining the bioavailability and metabolism of flavonoids, though greatly influenced by their chemical structure. However, nanoformulation is an emerging technique to improve biopharmaceutical fate and achieve target drug delivery. Thus, much attention should be given to identifying other possible chemical approaches for synthesizing flavonoids and improving their pharmacokinetic profiling, hence potentiating their efficacy in clinic.

Background: The main and common treatment of renal replacement therapy (RRT) for chronic kidney disease (CKD), especially in end-stage kidney disease (ESKD) patients, is hemodialysis (HD). Many reports have shown that exercise therapy is good for HD patients. This review aims to describe recent advances in exercise therapy in HD patients. Objective: Our key opinions have focused on varied types of exercise therapy and identified barriers to exercise therapy among HD patients. Exercise implementation includes aerobic exercise training, resistance exercise training, combined exercise training, and novel exercise interventions. Barriers include internal and external distress, such as HD patients' restrictions and environmental problems. Methods: This review is based on the novel/ most findings in PubMed, Web of Science, Google Scholar, and MEDLINE from the inception of every database until August 2022. Results: The systematic search strategy identified 6 articles that met the inclusion criteria. Four were specific to exercise therapy in HD, and three were to exercise barriers in HD. Massive evidence has demonstrated exercise therapy for HD has specific benefits and neglectful causes of exercise barriers. Conclusion: In this review, we aimed to summarize recent advances in individual exercise therapy recommendations (type, intensity, time, and frequency) and exercise barriers in HD patients. In conclusion, Low/moderate-intensity exercise trained for at least thirty minutes five times per week, including aerobic exercise (Walking, Jogging, Swimming, and Health Exercises), resistance training (Dumbbells, Band training, and Knee extension), and combination exercise (both) during the first 2 hours of dialysis treatment or non-dialysis days is advisable treatment recommendation.