Mitochondria-targeted ruthenium complexes can be generated in vitro and in living cells to target triple-negative breast cancer cells by autophagy inhibition.

Triple-negative breast cancer (TNBC) is the most aggressive type of breast cancer, which owned severe resistance to platinum-based anticancer agents. Herein, we report a new metal-arene complex, Ru-TPE-PPh3, which can be synthesized in vitro and in living cells with copper catalyzed the cycloaddition reaction of Ru-azide and alkynyl (CuAAC). The complex Ru-TPE-PPh3 exhibited superior inhibition of the proliferation of TNBC MDA-MB-231 cells with an IC50 value of 4.0 µM. Ru-TPE-PPh3 could induce the over production of reactive oxygen species (ROS) to initiate the oxidative stress, and further damage the mitochondria both functionally and morphologically, as loss of mitochondrial membrane potential (MMP) and cutting the supply of adenosine triphosphate (ATP), the disappearance of cristae structure. Moreover, the damaged mitochondria evoked the occurrence of mitophagy with the autophagic flux blockage and cell death. The complex Ru-TPE-PPh3 also demonstrated excellent anti-proliferative activity in 3D MDA-MB-231 multicellular tumor spheroids (MCTSs), indicating the potential to inhibit solid tumors in living cells. This study not only provided a potent agent for the TNBC treatment, but also demonstrated the universality of the bioorthogonally catalyzed lethality (BCL) strategy through CuAAC reation.

Consolidating Organometallic Complex Ir-CA Empowers Mitochondria-Directed Chemotherapy against Resistant Cancer via Stemness and Metastasis Inhibition.

Cancer treatment has faced severe obstacles due to the smart biological system of cancer cells. Herein, we report a three-in-one agent Ir-CA via attenuation of cancer cell stemness with the down-regulated biomarker CD133 expression from the mitochondria-directed chemotherapy. Over 80% of Ir-CA could accumulate in mitochondria, result in severe mitochondrial dysfunctions, and subsequently initiate mitophagy and cell cycle arrest to kill cisplatin-resistant A549R cells. In vitro and in vivo antimetastatic experiments demonstrated that Ir-CA can effectively inhibit metastasis with down-regulated MMP-2/MMP-9. RNA seq analysis and Western blotting indicated that Ir-CA also suppresses the GSTP1 expression to decrease the intracellular Pt-GS adducts, resulting in the detoxification and resensitization to cisplatin of A549R cells. In vivo evaluation indicated that Ir-CA restrains the tumor growth and has minimal side effects and superior biocompatibility. This work not only provides the first three-in-one agent to attenuate cancer cell stemness and simultaneously realize anticancer, antimetastasis, and conquer metallodrug resistance but also demonstrates the effectiveness of the mitochondria-directed strategy in cancer treatment.

Functional Upgrading of an Organo-Ir(III) Complex to an Organo-Ir(III) Prodrug as a DNA Damage-Responsive Autophagic Inducer for Hypoxic Lung Cancer Therapy.

The efficiency of nitrogen mustards (NMs), among the first chemotherapeutic agents against cancer, is limited by their monotonous mechanism of action (MoA). And tumor hypoxia is a significant obstacle in the attenuation of the chemotherapeutic efficacy. To repurpose the drug and combat hypoxia, herein, we constructed an organo-Ir(III) prodrug, IrCpNM, with the composition of a reactive oxygen species (ROS)-inducing moiety (Ir-arene fragment)-a hypoxic responsive moiety (azo linker)-a DNA-alkylating moiety (nitrogen mustard), and realized DNA damage response (DDR)-mediated autophagy for hypoxic lung cancer therapy for the first time. Prodrug IrCpNM could upregulate the level of catalase (CAT) to catalyze the decomposition of excessive H2O2 to O2 and downregulate the expression of the hypoxia-inducible factor (HIF-1α) to relieve hypoxia. Subsequently, IrCpNM initiates the quadruple synergetic actions under hypoxia, as simultaneous ROS promotion and glutathione (GSH) depletion to enhance the redox disbalance and severe oxidative and cross-linking DNA damages to trigger the occurrence of DDR-mediated autophagy via the ATM/Chk2 cascade and the PIK3CA/PI3K-AKT1-mTOR-RPS6KB1 signaling pathway. In vitro and in vivo experiments have confirmed the greatly antiproliferative capacity of IrCpNM against the hypoxic solid tumor. This work demonstrated the effectiveness of the DNA damage-responsive organometallic prodrug strategy with the microenvironment targeting system and the rebirth of traditional chemotherapeutic agents with a new anticancer mechanism.

Cyclometalated iridium(III) complexes as anti-breast cancer and anti-metastasis agents via STAT3 inhibition.

Breast cancer is the most commonly diagnosed cancer and second­leading cause of cancer deaths in women. Signal transducer and activator of transcription 3 (STAT3) plays a critical role in promoting breast cancer cell proliferation, invasion, angiogenesis, and metastasis, and the high expression of STAT3 is related to the occurrence and poor chemotherapy sensitivity of breast cancer. Iridium(III) complexes Ir-PTS-1- 4 containing a pterostilbene-derived ligand were synthesized to inhibit the STAT3 pathway in breast cancer. Ir-PTS-4 inhibited the proliferation of breast cancer cells by suppressing the expression of phosphorylated STAT3 and STAT3-related cyclin D1, arresting cell cycle in the S-phase, inducing DNA damage and reactive oxygen species (ROS) generation, eventually leading to autophagic cell death. The cell metastasis and invasion were also inhibited after Ir-PTS-4 treatment. Besides, Ir-PTS-4 exhibited excellent anti-proliferation activity in 3D multicellular tumor spheroids, showing potential for the treatment of solid tumors. This work presents the rational design of metal-based anticancer agents to block the STAT3 pathway for simultaneously inhibiting breast cancer proliferation and metastasis.

Evoking Ferroptosis by Synergistic Enhancement of a Cyclopentadienyl Iridium-Betulin Immune Agonist.

Ferroptosis is a form of programmed cell death driven by iron-dependent lipid peroxidation (LPO) with the potential for antitumor immunity activation. In this study, a nonferrous cyclopentadienyl metal-based ferroptosis inducer [Ir(Cp*)(Bet)Cl]Cl (Ir-Bet) was developed by a metal-ligand synergistic enhancement (MLSE) strategy involving the reaction of [Ir(Cp*)Cl]2 Cl2 with the natural product Betulin. The fusion of Betulin with iridium cyclopentadienyl (Ir-Cp*) species as Ir-Bet not only tremendously enhanced the antiproliferative activity toward cancer cells, but also activated ferritinophagy for iron homeostasis regulation by PI3K/Akt/mTOR cascade inhibition with a lower dosage of Betulin, and then evoked an immune response by nuclear factor kappa-B (NF-κB) activation of Ir-Cp* species. Further immunogenic cell death (ICD) occurred by remarkable ferroptosis through glutathione (GSH) depletion, glutathione peroxidase 4 (GPX4) deactivation and ferritinophagy. An in vivo vaccination experiment demonstrated desirable antitumor and immunogenic effects of Ir-Bet by increasing the ratio of cytotoxic T cells (CTLs)/regulatory T cells (Tregs).

Selectively attacking tumor cells of Ru/Ir-arene complexes based on meclofenamic acid via cyclooxygenase-2 inhibition.

Breast cancer (BC) is one of the most common malignant tumors and often accompanied by inflammatory processes. Inflammation is an essential component of the tumor microenvironment, which might influence tumor proliferation and metastasis. Herein, three metal-arene complexes MA-bip-Ru, MA-bpy-Ir, and MA-bpy-Ru were prepared by tethering the non-steroidal anti-inflammatory drug meclofenamic acid (MA). Among them, MA-bip-Ru and MA-bpy-Ir showed lower cytotoxicity towards cancer cells, but MA-bpy-Ru showed significantly high selectivity and cytotoxicity towards MCF-7 cells through the autophagic pathway and exhibited no toxicity against normal HLF cells, showing potential for selective treatment of tumor cells. MA-bpy-Ru could also effectively destroy the 3D multicellular tumor spheroids, demonstrating its potential for clinical application. Besides, MA-bip-Ru, MA-bpy-Ir, and MA-bpy-Ru exhibited anti-inflammatory properties superior to MA, notably downregulating the expression of cyclooxygenase-2 (COX-2) and inhibiting the secretion of prostaglandin E2 in vitro. These findings demonstrated that MA-bpy-Ru was capable of intervening in inflammatory processes and showed the potential of MA-bpy-Ru to act as a selective anticancer agent, thus presenting a new mechanism of action for metal-arene complexes.

Immunostimulation with chemotherapy of a ruthenium-arene complex via blockading CD47 signal in chronic myelogenous leukemia cells.

Combination of novel immunomodulation and traditional chemotherapy has become a new tendency in cancer treatment. Increasing evidence suggests that blocking the "don't eat me" signal transmitted by the CD47 can promote the phagocytic ability of macrophages to cancer cells, which might be promising for improved cancer chemoimmunotherapy. In this work, we conjugated CPI-alkyne modified by Devimistat (CPI-613) with ruthenium-arene azide precursor Ru-N3 by copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction to construct Ru complex CPI-Ru. CPI-Ru exhibited satisfactory cytotoxicity towards the K562 cells while nearly non-toxic towards the normal HLF cells. CPI-Ru has been demonstrated to cause severe damage to mitochondria and DNA, ultimately inducing cancer cell death through the autophagic pathway. Moreover, CPI-Ru could significantly downregulate the expression of CD47 on the surface of K562 accompanied by the enhanced immune response by targeting the blockade of CD47. This work provides a new strategy for utilizing metal-based anticancer agents to block CD47 signal to achieve chemoimmunotherapy in chronic myeloid leukemia treatment.

Self-Assembly Mitochondria-Targeting Donor-Acceptor Type Theranostic Nanosphere Activates ROS Storm for Multimodal Cancer Therapy.

The rational design of cancer theranostics with natural diagnostic information and therapeutic behavior has been considered to be a big challenge, since common theranostics from photothermal and photodynamic therapy need to be activated with external stimuli of photoirradiation to enable the chemotherapeutic effects. In this contribution, we have designed and synthesized a series of simple theranostic agents, TPA-N-n (n = 4, 8, 12), which could accumulate at the tumor site over 48 h and indicate superior antiproliferative performance in vivo. TPA-N-n was constructed with electron donor triphenylamine-acceptor benzothiadiazole-mitochondria-targeting moiety pyridinium. Complex TPA-N-8 indicated the best cytotoxicity to cancerous HeLa cells, with an IC50 value of 4.3 µM, and could self-assemble to a nanosphere with a size of 161.2 nm in the DMSO/PBS solution. It is worth noting that TPA-N-8 could accumulate in the mitochondria and produce major ROS species O2•- and OH• as well as small amounts of 1O2 without photoirradiation. Oxidative DNA damage is initiated due to the imbalance of intracellular redox homeostasis from the significant ROS storm. Multimodal synergistic therapy for HeLa cells was activated, as the PINK1-mediated mitophagy from the damaged mitochondria and DNA damage responsive (DDR) induced necroptosis and autophagy. This work not only provided a successful D-A type theranostic agent with superior anticancer performance from multimodal synergistic therapy but also further demonstrated the high efficacy of a mitochondria-targeting strategy for cancer treatment.

Switching the Mode of Cell Death between Apoptosis and Autophagy by Histone Deacetylase 6 Inhibition Levels.

Inhibition of histone deacetylase (HDAC) has been demonstrated to be an effective strategy for cancer treatment. In this work, we have developed a new agent Ir-VPA, which exhibits the cell death mode switching between apoptosis and autophagy due to the distinct level of HDAC6 inhibition. Ir-VPA indicates the best anticancer activity to HeLa cells, and could be hydrolyzed due to the high expression of the esterase in HeLa cells. Ir-VPA could accumulate in nuclei, induce severe DNA damages and cell cycle arrest at G2/M phase. The anticancer mechanism of Ir-VPA to HeLa cells was dependent on the HDAC6 inhibitory performance, as the caspase dependent apoptosis at low concentration (IC50 ) and autophagy with the autophagy flux blockage at high concentration (2×IC50 ). This is resulted from the distinct inhibitory levels of HDAC6, as moderate/complete inhibition at the concentration of IC50 /2×IC50 .In the presence of autophagic inhibitor chloroquine, the apoptotic population elevated from 32.7 % to 61.7 %, indicating that Ir-VPA could activate apoptotic process through the autophagolysosome fusion inhibition. Ir-VPA also exhibits excellent antiproliferative behavior to 3D HeLa multicellular tumor spheroids (MCTSs). This work not only provided a new HDAC6 inhibitor and novel anticancer mechanism for the effective treatment of cervical cancer, but also demonstrated the strategy to conjugate the metal fragment with active organic drug to enhance the anticancer performance.

Unlocking the potential of iridium and ruthenium arene complexes as anti-tumor and anti-metastasis chemotherapeutic agents.

It is a major challenge to design novel multifunctional metal-based chemotherapeutic agents for anti-tumor and anti-metastasis applications. Two complexes (OA-Ir and OA-Ru) were synthesized via CuAAC (copper-catalyzed azide-alkyne cycloaddition) reaction from nontoxic Ir-N3 or Ru-N3 species and low toxic alkynyl precursor OA-Alkyne, and exhibited satisfactory anti-tumor and anti-metastasis pharmacological effects. Conjugation of Oleanolic acid (OA) and metal-arene species significantly enhanced the cytotoxicity in A2780 cells compared to the precursors through mitochondrial-induced autophagy pathway. Moreover, the two complexes could inhibit the cell metastasis and invasion through damage of actin dynamics and down-regulation of MMP2/MMP9 proteins. Combination of two precursors improved the lipophilicity and biocompatibility, simultaneously enhanced the cell uptake and the mitochondrial accumulation of metal-arene complexes, which caused mitochondrial membrane potential damage, oxidative phosphorylation, ATP depletion and autophagy. Besides, OA-Ir and OA-Ru displayed excellent activity to disintegrate the 3D multicellular tumor spheroids, showing potential for the treatment of solid tumors. This work provides a new way for developing novel metal-based complexes via CuAAC reaction for simultaneously inhibiting tumor proliferation and metastasis.

The cyclometalated iridium (III) complex based on 9-Anthracenecarboxylic acid as a lysosomal-targeted anticancer agent.

9-Anthracenecarboxylic acid (9-Ac) was reported early as a chloride channel inhibitor and was found to exhibit significant anti-proliferative activity on leukemic cells, but has not been researched in solid tumor cells. Herein, a 9-anthraceneic acid derivative was introduced into the cyclometalated Iridium (III) species to construct a novel Iridium (Ir) complex Ir-9-Ac, [Ir(ppy)2(9-Ac-L)]PF6 (ppy = 2-phenylpyridine, 9-Ac-L = N-((4'-methyl-[2,2'-bipyridin]-4-yl)methyl)anthracene-9-carboxamide), which could accumulated in lysosomes. Ir-9-Ac showed good cytotoxic activity against several tumor cell lines, notably on A549 cells. Besides Ir-9-Ac could inhibit the cell colony formation and growth of the 3D cell spheroids, demonstrating the potential to suppress tumors in vivo. This design provided a platform for the design of cyclometalated Iridium (III) anticancer complexes.

A New Strategy to Fight Metallodrug Resistance: Mitochondria-Relevant Treatment through Mitophagy to Inhibit Metabolic Adaptations of Cancer Cells.

Metabolic adaptations can help cancer cells to escape from chemotherapeutics, mainly involving autophagy and ATP production. Herein, we report a new rhein-based cyclometalated IrIII complex, Ir-Rhein, that can accurately target mitochondria and effectively inhibit metabolic adaptations. The complex Ir-Rhein induces severe mitochondrial damage and initiates mitophagy to reduce the number of mitochondria and subsequently inhibit both mitochondrial and glycolytic bioenergetics, which eventually leads to ATP starvation death. Moreover, Ir-Rhein can overcome cisplatin resistance. Co-incubation experiment, 3D tumor spheroids experiment and transcriptome analysis reveal that Ir-Rhein shows promising antiproliferation performance for cisplatin-resistant cancer cells with the regulation of platinum resistance-related transporters. To our knowledge, this is a new strategy to overcome metallodrug resistance with a mitochondria-relevant treatment.

Fighting metallodrug resistance through alteration of drug metabolism and blockage of autophagic flux by mitochondria-targeting AIEgens.

Metallodrug resistance has attracted a great deal of attention in cancer treatment. According to the cisplatin (cis-Pt) anticancer mechanism, a new strategy to overcome cis-Pt resistance through mitochondrial dysfunction is proposed. Two mitochondria-targeted aggregation-induced emission fluorogens (AIEgens) were first synthesized, named DP-PPh3 and TPE-PPh3, which showed superior capacities to overcome the cis-Pt resistance of lung cancer cells (A549R) by the alteration of drug metabolism (up-regulation of influx CTR1 and down-regulation of efflux MRP2) and blockage of autophagic flux (failure of the degradation of autophagosomes). This study is the first time that AIEgens are utilized in the treatment of cis-Pt resistant cancer cells. Moreover, the underlying molecular mechanism was fully revealed. Triphenylphosphonium (PPh3)-decorated AIEgens DP-PPh3 and TPE-PPh3 not only successfully realized aggregation and the imaging of mitochondria in A549R cells, but also activated cytotoxicity towards A549R cells. DP-PPh3 and TPE-PPh3 could induce ROS production, disrupt the mitochondrial structure, and impair mitochondrial and glycolytic metabolism. Furthermore, the anticancer efficacy of these drugs was demonstrated in 3D multicellular tumor spheroids (MCTSs) of A549R cells in vitro and in tumor-bearing nude mice in vivo. This AIE-PPh3 strategy not only promoted cytotoxicity towards cancer cells but also provided a new pathway for the treatment of metallodrug resistance.

Biotinylated curcumin as a novel chemosensitizer enhances naphthalimide-induced autophagic cell death in breast cancer cells.

Achieving selective release of chemical anticancer agents and improving therapeutic efficacy has always been a hot spot in the field of cancer research, yet how to achieve this remains a great challenge. In this work, we constructed a novel chemical anticancer agent (named MCLOP) by introducing naphthalimide into the skeleton of methylene blue (MB). Under the stimulation by cellular hypochlorous acid (HClO) and visible light, selective release of active naphthalimide can be achieved within breast cancer cell lines, the release process of which can be tracked visually using near-infrared fluorescence of MB (685 nm). More importantly, we developed biotinylated curcumin (Cur-Bio) as a new chemosensitizer, which significantly enhanced the ability of MCLOP to induce autophagic cell death of breast cancer cells. This synergistic treatment strategy exhibited an excellent anti-proliferation effect on breast cancer cells in vitro, three-dimensional (3D) cell sphere model, and mouse tumor model in vivo. This work provides a new strategy for the treatment of breast cancer and also opens new opportunities for the efficient treatment of cancer with curcumin-based chemosensitizer.

Mitochondria-targeted Pt(IV) prodrugs conjugated with an aggregation-induced emission luminogen against breast cancer cells by dual modulation of apoptosis and autophagy inhibition.

Theranostic anticancer agents with dual functions of diagnosis and therapy are in highly demand for breast cancer. Herein, a triphenylphosphonium (TPP)-decorated aggregation-induced emission (AIE)-based Pt(IV) prodrug ACPt was developed, which exhibited superior anticancer performance with novel anticancer mechanism of dual modulation of apoptosis and autophagy inhibition. The experimental data showed that ACPt induced increased reactive oxygen species (ROS), and decreased mitochondrial membrane potential (MMP). The morphology and function of mitochondria were also severely damaged and ACPt showed strong inhibition to both mitochondrial and glycolytic bioenergetics. Moreover, DNA damage and cell cycle arrest in the S-phase were also observed after the ACPt treatment, eventually leading to the apoptosis and autophagy inhibition of cancer cells. Furthermore, ACPt also indicated excellent anti-proliferation activity in 3D multicellular tumor spheroids (MCTSs), suggesting the potential to inhibit solid tumors in vivo. Our observation demonstrated that ACPt could serve as a promising anticancer theranostic agent toward breast cancers for prodrug activation monitoring and image-guided chemotherapy.

Using bio-orthogonally catalyzed lethality strategy to generate mitochondria-targeting anti-tumor metallodrugs in vitro and in vivo.

Synthetic lethality was proposed nearly a century ago by geneticists and recently applied to develop precision anti-cancer therapies. To exploit the synthetic lethality concept in the design of chemical anti-cancer agents, we developed a bio-orthogonally catalyzed lethality (BCL) strategy to generate targeting anti-tumor metallodrugs both in vitro and in vivo. Metallodrug Ru-rhein was generated from two non-toxic species Ru-N3 and rhein-alkyne via exclusive endogenous copper-catalyzed azide alkyne cycloaddition (CuAAC) reaction without the need of an external copper catalyst. The non-toxic species Ru-arene complex Ru-N3 and rhein-alkyne were designed to perform this strategy, and the mitochondrial targeting product Ru-rhein was generated in high yield (>83%) and showed high anti-tumor efficacy in vitro. This BCL strategy achieved a remarkable tumor suppression effect on the tumor-bearing mice models. It is interesting that the combination of metal-arene complexes with rhein via CuAAC reaction could transform two non-toxic species into a targeting anti-cancer metallodrug both in vitro and in vivo, while the product Ru-rhein was non-toxic towards normal cells. This is the first example that exclusive endogenous copper was used to generate metal-based anti-cancer drugs for cancer treatment. The anti-cancer mechanism of Ru-rhein was studied and autophagy was induced by increased reactive oxygen species and mitochondrial damage. The generality of this BCL strategy was also studied and it could be extended to other metal complexes such as Os-arene and Ir-arene complexes. Compared with the traditional methods for cancer treatment, this work presented a new approach to generating targeting metallodrugs in vivo via the BCL strategy from non-toxic species in metal-based chemotherapy.

Photoactivated Osmium Arene Anticancer Complexes.

Half-sandwich Os-arene complexes exhibit promising anticancer activity, but their photochemistry has hardly been explored. To exploit the photocytotoxicity and photochemistry of Os-arenes, O,O-chelated complexes [Os(η6-p-cymene)(Curc)Cl] (OsCUR-1, Curc = curcumin) and [Os(η6-biphenyl)(Curc)Cl] (OsCUR-2), and N,N-chelated complexes [Os(η6-biphenyl)(dpq)I]PF6 (OsDPQ-2, dpq = pyrazino[2,3-f][1,10]phenanthroline) and [Os(η6-biphenyl)(bpy)I]PF6 (OsBPY-2, bpy = 2,2'-bipyridine), have been investigated. The Os-arene curcumin complexes showed remarkable photocytotoxicity toward a range of cancer cell lines (blue light IC50: 2.6-5.8 µM, photocytotoxicity index PI = 23-34), especially toward cisplatin-resistant cancer cells, but were nontoxic to normal cells. They localized mainly in mitochondria in the dark but translocated to the nucleus upon photoirradiation, generating DNA and mitochondrial damage, which might contribute toward overcoming cisplatin resistance. Mitochondrial damage, apoptosis, ROS generation, DNA damage, angiogenesis inhibition, and colony formation were observed when A549 lung cancer cells were treated with OsCUR-2. The photochemistry of these Os-arene complexes was investigated by a combination of NMR, HPLC-MS, high energy resolution fluorescence detected (HERFD), X-ray adsorption near edge structure (XANES) spectroscopy, total fluorescence yield (TFY) XANES spectra, and theoretical computation. Selective photodissociation of the arene ligand and oxidation of Os(II) to Os(III) occurred under blue light or UVA excitation. This new approach to the design of novel Os-arene complexes as phototherapeutic agents suggests that the novel curcumin complex OsCUR-2, in particular, is a potential candidate for further development as a photosensitizer for anticancer photoactivated chemotherapy (PACT).

Monitoring hydrogen polysulfide during ferroptosis with a two-photon fluorescent probe.

Hydrogen polysulfide (H2Sn, n > 1), a member of reactive sulfur species (RSS), is primarily generated during the crosstalk between H2S and reactive oxygen species (ROS), which plays important role in physiological and pathological processes. Ferroptosis is a new non-classical mode of cell death, in which ROS-associated lipid peroxidation and iron-dependent accumulation are the main features. However, the biological effects of H2Sn on ferroptosis and the detailed mechanisms of action remain poorly understood. Thus, there is an urgent need to develop highly selective and sensitive chemical tools for monitoring H2Sn in living cells. Herein, we develop a two-photon fluorescent probe (PSP) for specifically imaging H2Sn in live cells and tumor spheroids. This probe exhibited a sensitive and selective response to H2Sn, which had been used for imaging exogenous and endogenous H2Sn in living cells by confocal imaging and high content imaging. PSP exhibits excellent photo-stability and two-photon imaging performance when irradiating at 880 nm in 3D HeLa multicellular tumor spheroids. Importantly, our studies revealed that H2Sn levels were significantly up-regulated during ferroptosis. These excellent properties ensure that PSP is a promising two-photon probe for exploring the biological and pathological effects of H2Sn during ferroptosis.

A self-immolated fluorogenic agent triggered by H2S exhibiting potential anti-glioblastoma activity.

Glioblastoma is the most common and aggressive type of malignant brain tumor with poor survival and limited therapeutic options. Theranostic anticancer agents with dual functions of diagnosis and therapy are highly attractive. Self-immolation reaction is a promising approach for theranostic prodrugs triggered by the tumor microenvironment. Overexpression of hydrogen sulfide (H2S) in glioma cells becomes a potential stimulus for activating prodrugs. Herein, a novel H2S responsive agent (SNF) containing amonafide (ANF), a self-immolative linker and a trigger group has been developed for imaging and chemotherapy in living cells. SNF exhibited high selectivity and sensitivity towards H2S and also showed excellent lysosome-targeted capability. The activated SNF could translocate to the nucleus, causing DNA damage and blocking the cell cycle. More mechanistic studies indicated that SNF altered the mitochondrial membrane potential and induced autophagy in human glioblastoma-astrocytoma (U87MG). In addition, 3D multicellular U87MG tumor spheroids were used to further confirm the active drug release and high anti-proliferative activity of SNF. This approach may provide a general strategy for developing H2S-triggered prodrugs for synergic cancer therapy.

Hydrogen sulfide triggered molecular agent for imaging and cancer therapy.

We developed an activatable molecular reagent, PNF, triggered by intracellular H2S in the lysosome to release the therapeutic drug amonafide, which can escape from the lysosome into the nucleus to induce autophagy of cancer cells. PNF exhibits potent inhibitory activity against cisplatin-resistant tumor cell lines.