Amonafide-based H2O2-responsive theranostic prodrugs: Exploring the correlation between H2O2 level and anticancer efficacy

Leveraging the elevated hydrogen peroxide (H2O2) levels in cancer cells, H2O2-activated prodrugs have emerged as promising candidates for anticancer therapy. Notably, the efficacy of these prodrugs is influenced by the varying H2O2 levels across different cancer cell types. In this context, we have developed a novel H2O2-activated prodrug, PBE-AMF, which incorporates a phenylboronic ester (PBE) motif. Upon H2O2 exposure, PBE-AMF liberates the fluorescent and cytotoxic molecule amonafide (AMF), functioning as a theranostic agent. Our studies with PBE-AMF have demonstrated a positive correlation between intracellular H2O2 concentration and anticancer activity. The breast cancer cell line MDA-MB-231, characterized by high H2O2 content, showed the greatest susceptibility to this prodrug. Subsequently, we replaced the PBE structure with phenylboronic acid (PBA) to obtain the prodrug PBA-AMF, which exhibited enhanced stability, aqueous solubility, and tumor cell selectivity. This selectivity is attributed to its affinity for sialic acid, which is overexpressed on the surfaces of cancer cells. In vitro assays confirmed that PBA-AMF potently and selectively inhibited the proliferation of MDA-MB-231 cells, while sparing non-cancerous MCF-10A cells. Mechanistic investigations indicated that PBA-AMF impedes tumor proliferation by inhibiting DNA synthesis, reducing ATP levels, inducing apoptosis, and arresting the cell cycle. Our work broadens the range of small molecule H2O2-activated anticancer theranostic prodrugs, which are currently limited in number. We anticipate that the applications of PBA-AMF will extend to a wider spectrum of tumors and other diseases associated with increased H2O2 levels, thereby offering new horizons in cancer diagnostics and treatment.

A sequential dual-locked luminescent copper nanocluster probe for tumor cell imaging and killing

A sequential dual-locked luminescent copper nanoclusters (CuNCs) probe was designed and synthesized for the specific imaging and selective killing of tumor cells. This nanoprobe was prepared by first forming a Fe3+-coupled tannic acid (TA)-stabilized CuNCs (CuNCs-FeIII), which is in quenching state due to the electron transfer between CuNCs and Fe3+, and then coating a protectable layer of hyaluronic acid (HA) on the surface of CuNCs-FeIII to form the final dual-locked nanoprobe (CuNCs-FeIII@HA). When the nanoprobe of CuNCs-FeIII@HA target enter the tumor cells through CD44-HA receptor, HAase will first digest the HA layer of the nanoprobes, and then, GSH over-expressed in tumor cells will reduce Fe3+ to Fe2+, thus restoring the fluorescence emission of CuNCs and at the same time killing the tumor cells with the hydroxyl free radicals (∙OH) produced by the Fenton reaction between Fe2+ and H2O2. This sequential dual-locked luminescent nanoprobe of CuNCs-FeIII@HA has been successfully used for the specific imaging and selective killing of tumor cells.

Gas Therapy: Generating, Delivery, and Biomedical Applications

Oxygen (O2), nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H2S), and hydrogen (H2) with direct effects, and carbon dioxide (CO2) with complementary effects on the condition of various diseases are known as therapeutic gases. The targeted delivery and in situ generation of these therapeutic gases with controllable release at the site of disease has attracted attention to avoid the risk of gas poisoning and improve their performance in treating various diseases such as cancer therapy, cardiovascular therapy, bone tissue engineering, and wound healing. Stimuli-responsive gas-generating sources and delivery systems based on biomaterials that enable on-demand and controllable release are promising approaches for precise gas therapy. This work highlights current advances in the design and development of new approaches and systems to generate and deliver therapeutic gases at the site of disease with on-demand release behavior. The performance of the delivered gases in various biomedical applications is then discussed.

A nitric oxide and hydrogen sulfide dual-donating nanosystem for highly synergistic gas-radiotherapy against hepatocellular carcinoma

A drug delivery system (DDS) based on gold-capped mesoporous silica nanoparticles (MSN) is fabricated for loading NOSH-aspirin, a nitric oxide (NO) and hydrogen sulfide (H₂S) dual-donating cytotoxic molecule. The liver targeting and tumor microenvironment responsive properties of the nanosystem enable, for the first time, the concurrent delivery of NO and H₂S from a DDS into hepatocellular carcinoma (HCC) cells. Combined gas-radiotherapy (GT-RT) from drug-loaded DDS (NOSH@MSN-Au-Gal) and X-ray irradiation shows highly synergistic anti-cancer activity against both normoxic and hypoxic HCC cells. Further studies revealed that the combined GT-RT not only retains the well-known anticancer mechanism of NO, H₂S, and X-ray individually, but also alleviates HCC hypoxia via NO- and H₂S- involved unique pathways. In mice, the GT-RT greatly slows the growth of both subcutaneous and orthotopic HCC tumors and shows high biocompatibility. The current work is expected to promote the clinical application of combined GT-RT as an effective cancer treatment.

Gasotransmitters in the tumor microenvironment: Impacts on cancer chemotherapy (Review)

Nitric oxide, carbon monoxide and hydrogen sulfide are three endogenous gasotransmitters that serve a role in regulating normal and pathological cellular activities. They can stimulate or inhibit cancer cell proliferation and invasion, as well as interfere with cancer cell responses to drug treatments. Understanding the molecular pathways governing the interactions between these gases and the tumor microenvironment can be utilized for the identification of a novel technique to disrupt cancer cell interactions and may contribute to the conception of effective and safe cancer therapy strategies. The present review discusses the effects of these gases in modulating the action of chemotherapies, as well as prospective pharmacological and therapeutic interfering approaches. A deeper knowledge of the mechanisms that underpin the cellular and pharmacological effects, as well as interactions, of each of the three gases could pave the way for therapeutic treatments and translational research.

Recent Advances in Hydrogel-Mediated Nitric Oxide Delivery Systems Targeted for Wound Healing Applications

Despite the noticeable evolution in wound treatment over the centuries, a functional material that promotes correct and swift wound healing is important, considering the relative weight of chronic wounds in healthcare. Difficult to heal in a fashionable time, chronic wounds are more prone to infections and complications thereof. Nitric oxide (NO) has been explored for wound healing applications due to its appealing properties, which in the wound healing context include vasodilation, angiogenesis promotion, cell proliferation, and antimicrobial activity. NO delivery is facilitated by molecules that release NO when prompted, whose stability is ensured using carriers. Hydrogels, popular materials for wound dressings, have been studied as scaffolds for NO storage and delivery, showing promising results such as enhanced wound healing, controlled and sustained NO release, and bactericidal properties. Systems reported so far regarding NO delivery by hydrogels are reviewed.

Target-Binding Accelerated Response for Sensitive Detection of Basal H2O2 in Tumor Cells and Tissues via a Dual-Functional Fluorescence Probe

Aberrant production of H₂O₂ is involved in cancer. The levels of H₂O₂ are significantly higher in tumor cells than in normal cells. It is important to develop fluorescent probes to image basal H₂O₂ selectively in tumor cells. So far, a cancer cell-targeting probe to image basal H₂O₂ has not been reported. Thus, we developed a fluorescent probe, BBHP, which contains benzil as a H₂O₂-recognition site and biotin as a target binding motif for the selective and sufficient detection of H₂O₂ in tumor cells. BBHP enables a selective fluorescence turn-on response to H₂O₂. The binding of the probe with biotin receptors can greatly accelerate the fluorescence response to H₂O₂. As a result, BBHP can sufficiently image basal H₂O₂ in biotin receptor-positive cancer cells and tumor tissues. Finally, BBHP was successfully applied to discriminate between cancerous and normal tissues.

A near-infrared fluorescent probe based on the hemicyanine skeleton for the detection of hydrogen peroxide in vivo

As a member of the reactive oxygen species, hydrogen peroxide (H₂O₂) plays critical roles in oxidative stress and cell signaling. Intracellular abnormal levels of H₂O₂ production are closely related to many diseases. Therefore, the real-time monitoring of H₂O₂ in the cells is important. In this work, we designed a novel fluorescent probe (Mito-H₂O₂) for the specific detection of H₂O₂ based on the hemicyanine skeleton, with bright near-infrared fluorescence emission. Mito-H₂O₂ displayed fast response, excellent water-solubility and great fluorescence intensity enhancement after the addition of H₂O₂. Furthermore, Mito-H₂O₂ has been successfully applied to image both of the exogenous and endogenous H₂O₂ in cells and mice with negligible cytotoxity.

Direct oxidation of N-ynylsulfonamides into N-sulfonyloxoacetamides with DMSO as a nucleophilic oxidant

N-Arylethynylsulfonamides are oxidized into N-sulfonyl-2-aryloxoacetamides directly and efficiently with dimethyl sulfoxide (DMSO) as both an oxidant and solvent with microwave assistance. DFT calculations indicate that DMSO nucleophilically attacks the ethylic triple bond and transfers its oxygen atom to the triple bond to form zwitterionic anionic N-sulfonyliminiums to trigger the reaction. Then it nucleophilically attacks the generated iminium intermediates to accomplish the oxidation via the second oxygen atom transfer. The current method provides a straightforward and efficient strategy to transform various N-arylethynylsulfonamides into N-sulfonyl-2-aryloxoacetamides, sulfonyl oxoacetimides, without any other electrophilic activators or oxidants.

Diversification of α-ketoamides via transamidation reactions with alkyl and benzyl amines at room temperature

A wide range of N-tosyl α-ketoamides underwent transamidation with various alkyl amines in the absence of a catalyst, base, or additive. On the other hand, transamidation in N-Boc α-ketoamides was achieved in the presence of Cs₂CO₃. The reactions proceeded at room temperature and provided good to excellent yields of transamidation products under the optimized conditions. Broad substrate scope, functional group tolerance and quick conversions are the important features of the developed methodology.

Recent advances in the development of nitric oxide-releasing biomaterials and their application potentials in chronic wound healing

Chronic wounds, such as pressure ulcers, vascular ulcers and diabetic foot ulcers (DFUs), often stay in a state of pathological inflammation and suffer from persistent infection, excess inflammation, and hypoxia, thus they are difficult to be healed. Nitric oxide (NO) plays a critical role in the regulation of various wound healing processes, including inflammatory response, cell proliferation, collagen formation, antimicrobial action and angiogenesis. The important role of NO in wound healing attracts intensive research focus on NO-based wound healing therapy. However, the application of NO gas therapy needs to resolve the intrinsic shortcomings of gas therapy, such as short storage and release times as well as temporal and spatial uncontrollability of the release mode. So far, various types of NO donors, including organic nitrates (RONO2), nitrites (RONO), S-nitrosothiols (RSNOs), nitrosamines, N-diazeniumdiolates (NONOates), and metal-NO complexes, have been developed to solidify gaseous NO and they were further encapsulated in or conjugated onto a variety of biomaterial vectors to develop NO delivery systems. NO synthetic enzyme mimics to catalyze the production and release of NO from l-arginine have also been developed. This paper reviews recent advances of NO donors, biomaterial vectors, thus-formed NO delivery systems, as well as recently emerged NO synthetic enzyme mimics. Furthermore, this review also summarizes the functions of NO releasing biomaterials that would benefit chronic wound healing, including antibacterial properties and the promotion of angiogenesis, as well as the convenient combination of light/thermal induced NO release with light/thermal therapies, and the prospects for future developing trends in this area.

Nitric oxide-donating and reactive oxygen species-responsive prochelators based on 8-hydroxyquinoline as anticancer agents

Metal ion chelators based on 8-hydroxyquinoline (8-HQ) have been widely explored for the treatment of many diseases. When aimed at being developed into potent anticancer agent, a largely unmet issue is how to avoid nonspecific chelation of metal ions by 8-HQ in normal cells or tissues. In the current work, a two-step strategy was employed to both enhance the anticancer activity of 8-HQ and improve its cancer cell specificity. Considering the well-known anticancer activity of nitric oxide (NO), NO donor furoxan was first connected to 8-HQ to construct HQ-NO conjugates. These conjugates were screened for their cytotoxicity, metal-binding ability, and NO-releasing efficiency. Selected conjugates were further modified with a ROS-responsive moiety to afford prochelators. Among all the target compounds, prodrug HQ-NO-11 was found to potently inhibit the proliferation of many cancer cells but not normal cells. The abilities of metal chelation and NO generation by HQ-NO-11 were confirmed by various methods and were demonstrated to be essential for the anticancer activity of HQ-NO-11. In vivo studies revealed that HQ-NO-11 inhibited the growth of SW1990 xenograft to a larger extent than 8-HQ. Our results showcase a general method for designing novel 8-HQ derivatives and shed light on obtaining more controllable metal chelators.

Nitric Oxide as a Potential Adjuvant Therapeutic for Neuroblastoma: Effects of NO on Murine N2a Cells

Neuroblastoma, the most common extracranial solid tumor in children, accounts for 15% of all pediatric cancer deaths. Pharmaceutical applications of S-Nitrosylation, which, under normal conditions is involved with a host of epigenetic and embryological development pathways, have exhibited great potential for use as adjuvant therapeutics in the clinical management of cancer. Herein, an evaluation of the impact of nitric oxide (NO) as a potent anticancer agent on murine neuroblastoma cells is presented. Excitingly cell viability, colony formation, and non-carcinogenic cell analysis illustrate the significance and practicality of NO as a cytotoxic anticancer therapeutic. Resazurin, WST-8 (2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt), and MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphyltetrazolium bromide) assays consistently displayed a moderate, ~20-25% reduction in cell viability after exposure to 1 mM S-Nitrosoglutathione (GSNO). A colony formation assay demonstrated that treated cells no longer exhibited colony formation capacity. Identically GSNO-treated Adult Human Dermal Fibroblasts (HDFa) exhibited no decrease in viability, indicating potential discrimination between neoplastic and normal cells. Collectively, our findings indicate a potential application for NO as an adjuvant therapeutic in the clinical management of neuroblastoma.