Tuning NO release of organelle-targeted furoxan derivatives and their cytotoxicity against lung cancer cells

FS536, a novel nitric oxide-releasing doxorubicin hybrid, reverts multidrug resistance in lung cancer cells

The design of molecular hybrids that chemically conjugate nitric oxide (NO)-donors with anticancer drugs, offering site-specific and time-controlled properties, is a promising strategy in cancer therapy. In this work, we designed, synthesized, and characterized a novel doxorubicin (DOXO)-NO-donor hybrid, named FS536, by chemically conjugating DOXO with a diazeniumdiolate moiety. Upon incubation in human serum, FS536 simultaneously released both DOXO and NO through enzymatic hydrolysis. FS536 significantly inhibited the proliferation of the DOXO-resistant A549 lung cancer cell line (A549-DR), overcoming the resistance typically observed with DOXO alone. This enhanced efficacy is attributed to the release of NO, which induces the nitration of the MRP1 efflux pump, reducing its activity, increasing intracellular drug concentrations, and thus sensitizing resistant cells to DOXO. Our findings suggest that FS536 is a promising therapeutic strategy for combating multidrug-resistant cancers by leveraging the synergistic effects of DOXO and NO.

Synthesis of Arginase Inhibitors: An Overview

Arginase (ARG) is a binuclear manganese-containing metalloenzyme that can convert L-arginine to L-ornithine and urea and plays a key role in the urea cycle. It also mediates different cellular functions and processes such as proliferation, senescence, apoptosis, autophagy, and inflammatory responses in various cell types. In mammals, there are two isoenzymes, ARG-1 and ARG-2; they are functionally similar, but their coding genes, tissue distribution, subcellular localization, and molecular regulation are distinct. In recent decades, the abnormal expression of ARG-1 or ARG-2 has been reported to be increasingly linked to a variety of diseases, including cardiovascular disease, inflammatory bowel disease, Alzheimer's disease, and cancer. Therefore, considering the current relevance of this topic and the need to address the growing demand for new and more potent ARG inhibitors in the context of various diseases, this review was conceived. We will provide an overview of all classes of ARG inhibitors developed so far including compounds of synthetic, natural, and semisynthetic origin. For the first time, the synthesis protocol and optimized reaction conditions of each molecule, including those reported in patent applications, will be described. For each molecule, its inhibitory activity in terms of IC50 towards ARG-1 and ARG-2 will be reported specifying the type of assay conducted.

Opportunities and Challenges of Arginase Inhibitors in Cancer: A Medicinal Chemistry Perspective

The overexpression of two arginase (ARG) isoforms, ARG1 and ARG2, contributes to the onset of numerous disorders, including cardiovascular and immune-mediated diseases, as well as tumors. To elucidate the specific roles of ARG1 and ARG2 without interfering with their physiological functions, it is crucial to develop effective ARG inhibitors that target only one isoform, while maintaining low toxicity and an adequate pharmacokinetic profile. In this context, we present a comprehensive overview of the different generations of ARG inhibitors. Given the general lack of selectivity in most existing inhibitors, we analyzed the structural features and plasticity of the ARG1 and ARG2 binding sites to explore the potential for designing inhibitors with novel binding patterns. We also review ongoing preclinical and clinical studies on selected inhibitors, highlighting both progress and challenges in developing potent, selective ARG inhibitors. Furthermore, we discuss medicinal chemistry strategies that may accelerate the discovery of selective ARG inhibitors.

Proteomics Studies Suggest That Nitric Oxide Donor Furoxans Inhibit In Vitro Vascular Smooth Muscle Cell Proliferation by Nitric Oxide-Independent Mechanisms

Physiologically, smooth muscle cells (SMC) and nitric oxide (NO) produced by endothelial cells strictly cooperate to maintain vasal homeostasis. In atherosclerosis, where this equilibrium is altered, molecules providing exogenous NO and able to inhibit SMC proliferation may represent valuable antiatherosclerotic agents. Searching for dual antiproliferative and NO-donor molecules, we found that furoxans significantly decreased SMC proliferation in vitro, albeit with different potencies. We therefore assessed whether this property is dependent on their thiol-induced ring opening. Indeed, while furazans (analogues unable to release NO) are not effective, furoxans' inhibitory potency parallels with the electron-attractor capacity of the group in 3 of the ring, making this effect tunable. To demonstrate whether their specific block on G1-S phase could be NO-dependent, we supplemented SMCs with furoxans and inhibitors of GMP- and/or of the polyamine pathway, which regulate NO-induced SMC proliferation, but they failed in preventing the antiproliferative effect. To find the real mechanism of this property, our proteomics studies revealed that eleven cellular proteins (with SUMO1 being central) and networks involved in cell homeostasis/proliferation are modulated by furoxans, probably by interaction with adducts generated after degradation. Altogether, thanks to their dual effect and pharmacological flexibility, furoxans may be evaluated in the future as antiatherosclerotic molecules.

Recent progress in synthesis and application of furoxan

This review highlights recent developments in the synthesis and application of furoxan. The chemistry of furoxan is relatively underdeveloped compared to that of other heterocycles owing to its difficult synthesis, which is ascribed to the labile nature of this molecule under various reaction conditions. Nevertheless, recent studies have conducted a variety of bond-forming reactions on the furoxan ring via a post-ring introduction of substituents (PRIS) strategy. This strategy enables the synthesis of furoxan molecules of interest more directly than the conventional methods that rely on the pre-installation of substituents on the furoxan ring precursors. In this review, the PRIS strategy for furoxan synthesis is classified and discussed according to the type of bond formed. Additionally, recent progress in the application of furoxan molecules, predominantly facilitated by the development of new synthetic methods, is covered in this review.

New Nitric Oxide-Releasing Compounds as Promising Anti-Bladder Cancer Drugs

Bladder cancer is a worldwide problem and improved therapies are urgently needed. In the search for newer strong antitumor compounds, herein, we present the study of three nitric oxide-releasing compounds and evaluate them as possible therapies for this malignancy. Bladder cancer cell lines T24 and 253J were used to evaluate the antiproliferative, antimigratory, and genotoxic effects of compounds. Moreover, we determined the NF-κB pathway inhibition, and finally, the survivin downregulation exerted by our molecules. The results revealed that compounds 1 and 3 exerted a high antiproliferative activity against bladder cancer cells through DNA damage and survivin downregulation. In addition, compound 3 reduced bladder cancer cell migration. We found that nitric oxide donors are promising molecules for the development of a new therapeutic targeting the underlying mechanisms of tumorigenesis and progression of bladder cancer.

Recent progress in nitric oxide-generating nanomedicine for cancer therapy

Nitric oxide (NO) is an endogenous, multipotent biological signaling molecule that participates in several physiological processes. Recently, exogenous supplementation of tumor tissues with NO has emerged as a potential anticancer therapy. In particular, it induces synergistic effects with other conventional therapies (such as chemo-, radio-, and photodynamic therapies) by regulating the activity of P-glycoprotein, acting as a vascular relaxant to relieve tumor hypoxia, and participating in the metabolism of reactive oxygen species. However, NO is highly reactive, and its half-life is relatively short after generation. Meanwhile, NO-induced anticancer activity is dose-dependent. Therefore, the targeted delivery of NO to the tumor is required for better therapeutic effects. In the past decade, NO-generating nanomedicines (NONs), which enable sustained and specific NO release in tumor tissues, have been developed for enhanced cancer therapy. This review describes the recent efforts and preclinical achievements in the development of NON-based cancer therapies. The chemical structures employed in the fabrication of NONs are summarized, and the strategies involved in NON-based cancer therapies are elaborated.

Greener Synthesis of Antiproliferative Furoxans via Multicomponent Reactions

Prostate and bladder cancers are commonly diagnosed malignancies in men. Several nitric oxide donor compounds with strong antitumor activity have been reported. Thus, continuing with our efforts to explore the chemical space around bioactive furoxan moiety, multicomponent reactions were employed for the rapid generation of molecular diversity and complexity. We herein report the use of Ugi and Groebke-Blackburn-Bienaymé multicomponent reactions under efficient, safe, and environmentally friendly conditions to synthesize a small collection of nitric-oxide-releasing molecules. The in vitro antiproliferative activity of the synthesized compounds was measured against two different human cancer cell lines, LNCaP (prostate) and T24 (bladder). Almost all compounds displayed antiproliferative activity against both cancer cell lines, providing lead compounds with nanomolar GI50 values against the cancer bladder cell line with selectivity indices higher than 10.

Synthesis and biological evaluation of NO-donor containing photosensitizers to induce ferroptosis of cancer cells

Photodynamic therapy (PDT) is a non-invasive treatment method for tumors by exciting photosensitizers (PS) upon light irradiation to generate cytotoxic reactive oxygen species (ROS). However, the low oxygen concentration near the tumor tissue limits the therapeutic effect of PDT. Herein, we synthesized six chlorin e6 derivatives containing NO-donors to enhance their antitumor activity by synergistic effect of ROS and NO. The results revealed that the new NO-donor containing photosensitizers (PS-NO) exhibited more potent photodynamic activity than chlorin e6, and the introduction of NO donor moieties to chlorin e6 increased the level of NO and ROS in cells. The addition of Ferrostatin-1, a ferroptosis inhibitor, markedly reduced the photodynamic activity of PS-NO as well as the level of NO and ROS in cells. Mechanism studies further showed that PS-NO could reduce intracellular GSH level, inhibit GPX4 activity and promote malondialdehyde (MDA) accumulation upon light irradiation, which suggested the ferroptosis mechanism underlying the PDT effect of PS-NO.

Recent Advances in the Synthesis and Biomedical Applications of Heterocyclic NO-Donors

Nitric oxide (NO) is a key signaling molecule that acts in various physiological processes such as cellular metabolism, vasodilation and transmission of nerve impulses. A wide number of vascular diseases as well as various immune and neurodegenerative disorders were found to be directly associated with a disruption of NO production in living organisms. These issues justify a constant search of novel NO-donors with improved pharmacokinetic profiles and prolonged action. In a series of known structural classes capable of NO release, heterocyclic NO-donors are of special importance due to their increased hydrolytic stability and low toxicity. It is no wonder that synthetic and biochemical investigations of heterocyclic NO-donors have emerged significantly in recent years. In this review, we summarized recent advances in the synthesis, reactivity and biomedical applications of promising heterocyclic NO-donors (furoxans, sydnone imines, pyridazine dioxides, azasydnones). The synthetic potential of each heterocyclic system along with biochemical mechanisms of action are emphasized.