Light activation of iridium(III) complexes driving ROS production and DNA damage enhances anticancer activity in A549 cells

A dual responsive nitric oxide / β-lapachone co-delivery platform for redox imbalance-enhanced tumor therapy

Nitric oxide (NO) / β-Lapachone (Lap) combined therapy by causing oxidative stress is an effective tumor therapy strategy. Herein, a dual-responsive lipid nanoparticles (LNPs) LSNO for NO / Lap co-delivery were constructed from the zinc-coordinated lipid (DSNO(Zn)) and the hydrophobic drug Lap in the presence of helper lipids (DOPE and DSPE-PEG2000). The zinc-coordinated structure in LSNO might elevate the Zn2+ content in tumor cells, contributing to antioxidant imbalance. The fluorescent assays proved the light-triggered NO release and fluorescent self-reporting abilities of LSNO. In addition, the LNPs had good drug release behavior under high concentration of GSH, indicating the NO / drug co-delivery capacity. In vitro antitumor assays showed that the NO / Lap combination treatment group could induce more significant tumor cell growth inhibition and cell apoptosis than individual NO or Lap treatment. The following mechanism studies revealed that NO / Lap combination treatment led to distinct oxidative stress by producing reactive oxygen species (ROS) and peroxynitrite anion (ONOO-). On the other hand, the intracellular redox balance could be further disrupted by Lap-induced NADPH consumption and Zn2+ / NO-induced reductase activities downregulation, thus promoting the degree of cell damage. Besides, it was also found that NO and Lap could directly damage nuclear DNA and induce mitochondrial dysfunction, thereby leading to caspase-3 activation and tumor cell death. These results proved that LSNO could serve as a promising multifunctional tumor therapy platform.

Synthesis, characterization and irradiation enhances anticancer activity of liposome-loaded iridium(III) complexes

Herein, we synthesized and characterized two novel iridium (III) complexes: [Ir(bzq)2(PPD)](PF6) (4a, with bzq = deprotonated benzo[h]quinoline and PPD = pteridino[6,7-f][1,10]phenanthroline-11,13-diamine) and [Ir(piq)2(PPD)](PF6) (4b, with piq = deprotonated 1-phenylisoquinoline). The anticancer efficacy of these complexes, 4a and 4b, was investigated using 3-(4,5-dimethylthiazole)-2,5-diphenltetraazolium bromide (MTT). Complex 4a exhibited no cytotoxic activity, while 4b demonstrated moderate efficacy against SGC-7901, A549, and HepG2 cancer cells. To enhance their anticancer potential, we explored two strategies: (I) light irradiation and (II) encapsulation of the complexes in liposomes, resulting in the formation of 4alip and 4blip. Both strategies significantly increased the ability of 4a, 4b to kill cancer cells. The cellular studies indicated that both the free complexes 4a, 4b and their liposomal forms 4alip and 4blip effectively inhibited cell proliferation. The cell cycle arrest analysis uncovered 4alip and 4blip arresting cell growth in the S period. Additionally, we investigated apoptosis and ferroptosis pathways, observing an increase in malondialdehyde (MDA) levels, a reduction of glutathione (GSH), a down-regulation of GPX4 (glutathione peroxidase) expression, and lipid peroxidation. The effects on mitochondrial membrane potential and intracellular Ca2+ concentrations were also examined, revealing that both light-activated and liposomal forms of 4alip and 4blip caused a decline in mitochondrial membrane potential and an enhancement in intracellular Ca2+ levels. In conclusion, these complexes and them encapsulated liposomes induce cell death through apoptosis and ferroptosis.

White light increases anticancer effectiveness of iridium(III) complexes toward lung cancer A549 cells

Anticancer activity has been extensively studies. In this article, three ligands 2-(6-bromobenzo[d][1,3]dioxol-5-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (BDIP), 2-(7-methoxybenzo[d][1,3]dioxol-5-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (MDIP), 2-(6-nitrobenzo[d][1,3]dioxol-5-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (NDIP) and their iridium(III) complexes: [Ir(ppy)2(BDIP)](PF6) (ppy = deprotonated 2-phenylpyridine, 3a), [Ir(ppy)2(MDIP)](PF6) (3b) and [Ir(ppy)2(NDIP)](PF6) (3c) were synthesized. The cytotoxicity of 3a, 3b, 3c against Huh7, A549, BEL-7402, HepG2, HeLa, and non-cancer NIH3T3 was tested using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method. The results obtained from the MTT test stated clearly that these complexes demonstrated moderate or non-cytotoxicity toward Huh7, BEL-7402, HepG2 and HeLa except A549 cells. To improve the anticancer efficacy, we used white light to irradiate the mixture of cells and complexes for 30 min, the anticancer activity of the complexes was greatly enhanced. Particularly, 3a and 3b exhibited heightened capability to inhibit A549 cells proliferation with IC50 (half maximal inhibitory concentration) values of 0.7 ± 0.3 μM and 1.8 ± 0.1 μM, respectively. Cellular uptake has shown that 3a and 3b can be accumulated in the cytoplasm. Wound healing and colony forming showed that 3a and 3b significantly hinder the cell migration and growth in the S phase. The complexes open mitochondrial permeability transition pore (MPTP) channel and cause the decrease of membrane potential, release of cytochrome C, activation of caspase 3, and finally lead to apoptosis. In addition, 3a and 3b cause autophagy, increase the lipid peroxidation and lead to ferroptosis. Also, 3a and 3b increase the expression of calreticulin (CRT), high mobility group box 1 (HMGB1), heat shock protein 70 (HSP70), thereby inducing immunogenic cell death.

Systematic review on antibacterial photodynamic therapeutic effects of transition metals ruthenium and iridium complexes

The prevalence of antibiotic-resistant pathogenic bacteria poses a significant threat to public health and ranks among the principal causes of morbidity and mortality worldwide. Antimicrobial photodynamic therapy is an emerging therapeutic technique that has excellent potential to embark upon antibiotic resistance problems. The efficacy of this therapy hinges on the careful selection of suitable photosensitizers (PSs). Transition metal complexes, such as Ruthenium (Ru) and Iridium (Ir), are highly suitable for use as PSs because of their surface plasmonic resonance, crystal structure, optical characteristics, and photonics. These metals belong to the platinum family and exhibit similar chemical behavior due to their partially filled d-shells. Ruthenium and Iridium-based complexes generate reactive oxygen species (ROS), which interact with proteins and DNA to induce cell death. As photodynamic therapeutic agents, these complexes have been widely studied for their efficacy against cancer cells, but their potential for antibacterial activity remains largely unexplored. Our study focuses on exploring the antibacterial photodynamic effect of Ruthenium and Iridium-based complexes against both Gram-positive and Gram-negative bacteria. We aim to provide a comprehensive overview of various types of research in this area, including the structures, synthesis methods, and antibacterial photodynamic applications of these complexes. Our findings will provide valuable insights into the design, development, and modification of PSs to enhance their photodynamic therapeutic effect on bacteria, along with a clear understanding of their mechanism of action.

Abrogation of KLF5 sensitizes BRCA1-proficient pancreatic cancer to PARP inhibition

Poly ADP-ribose polymerase (PARP) inhibitor monotherapies are selectively effective in patients with pancreatic, breast, prostate, and ovarian cancers with BRCA1 mutations. Cancer patients with more frequent wild-type BRCA show poor responses to PARP inhibitors. Moreover, patients who are initially sensitive to these inhibitors eventually respond poorly to drugs. In the present study, we discover that abrogation of Kruppel-like factor 5 (KLF5) significantly inhibits homologous recombination, which is the main mechanism for DNA double-stranded repair. Furthermore, the downregulation of KLF5 expression promotes the DNA damage induced by olaparib and significantly reduces the IC 50 of the RARP inhibitor in pancreatic cancer cells. Overexpression of BRCA1 reverses the above effects caused by silencing of KLF5. Olaparib combined with a KLF5 inhibitor has an enhanced cytotoxic effect. Mechanistically, we identify BRCA1 as a KLF5 target gene. BRCA1 is positively correlated with KLF5 in PDAC tissue. Our results indicate that inhibition of KLF5 may induce BRCAness in a larger pancreatic cancer subset with proficient BRCA. The combination of KLF5 inhibitors and PARP inhibitors provides a novel treatment strategy to enhance the sensitivity of BRCA1-proficient pancreatic cancer to PARP inhibitors.

Semi-synthesis and structure-activity relationship study yield antibacterial vicenistatin derivatives with low cytotoxicity

Vicenistatin (1) is a 20-membered polyketide macrocyclic antibiotic with potent antimicrobial and cytotoxic activities. In this study, to further explore the potential of 1 as candidates of antibacterial drug development, 4'-N-demethyl vicenistatin (2), a secondary metabolite obtained from the ∆vicG mutant strain of Monodonata labio-associated Streptomyces parvus SCSIO Mla-L010, was utilized as a starting material for modifications of 4'-amino group of vicenistatin. Six new vicenistatin derivatives (3-8) were semi-synthesized through a concise route of amino modification with various aliphatic and aromatic aldehydes. Our study reveals that the bioactivity of vicenistatin is closely related to amino modification in sugar moiety, which results from the length of alkyl side chain as well as the presence of electron withdrawing/denoting group on the benzene ring. Importantly, compounds 4 with a butyl group and 8 with a 3,5-dihydroxyl-benzyl group at 4'-amino group, respectively, exhibited good antimicrobial activities, with MIC values spanning 0.5-4 μg ml-1 to Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis, Micrococcus luteus and Bacillus subtilis, with low cytotoxicity. This research promotes the further exploration of structure-activity relationships of vicenistatin and provides new vicenistatin derivatives for development of future anti-infectious agents with reduced cytotoxicity.

Photoactivatable, mitochondria targeting dppz iridium(III) complex selectively interacts and damages mitochondrial DNA in cancer cells

Cyclometalated Ir(III) complex [Ir(L)2(dppz)]PF6 (where L = 1-methyl-2-(thiophen-2-yl)-1H-benzo[d]imidazole and dppz = dipyrido [3,2-a:2',3'-c]phenazine) (Ir1) is potent anticancer agent whose potency can be significantly increased by irradiation with blue light. Structural features of the cyclometalated Ir(III) complex Ir1 investigated in this work, particularly the presence of dppz ligand possessing an extended planar area, suggest that this complex could interact with DNA. Here, we have shown that Ir1 accumulates predominantly in mitochondria of cancer cells where effectively and selectively binds mitochondrial (mt)DNA. Additionally, the results demonstrated that Ir1 effectively suppresses transcription of mitochondria-encoded genes, especially after irradiation, which may further affect mitochondrial (and thus also cellular) functions. The observation that Ir1 binds selectively to mtDNA implies that the mechanism of its biological activity in cancer cells may also be connected with its interaction and damage to mtDNA. Further investigations revealed that Ir1 tightly binds DNA in a cell-free environment, with sequence preference for GC over AT base pairs. Although the dppz ligand itself or as a ligand in structurally similar DNA-intercalating Ru polypyridine complexes based on dppz ligand intercalates into DNA, the DNA binding mode of Ir1 comprises surprisingly a groove binding rather than an intercalation. Also interestingly, after irradiation with visible (blue) light, Ir1 was capable of cleaving DNA, likely due to the production of superoxide anion radical. The results of this study show that mtDNA damage by Ir1 plays a significant role in its mechanism of antitumor efficacy. In addition, the results of this work are consistent with the hypothesis and support the view that targeting the mitochondrial genome is an effective strategy for anticancer (photo)therapy and that the class of photoactivatable dipyridophenazine Ir(III) compounds may represent prospective substances suitable for further testing.

Harnessing Hyperthermia: Molecular, Cellular, and Immunological Insights for Enhanced Anticancer Therapies

Hyperthermia, the raising of tumor temperature (≥39°C), holds great promise as an adjuvant treatment for cancer therapy. This review focuses on 2 key aspects of hyperthermia: its molecular and cellular effects and its impact on the immune system. Hyperthermia has profound effects on critical biological processes. Increased temperatures inhibit DNA repair enzymes, making cancer cells more sensitive to chemotherapy and radiation. Elevated temperatures also induce cell cycle arrest and trigger apoptotic pathways. Furthermore, hyperthermia modifies the expression of heat shock proteins, which play vital roles in cancer therapy, including enhancing immune responses. Hyperthermic treatments also have a significant impact on the body's immune response against tumors, potentially improving the efficacy of immune checkpoint inhibitors. Mild systemic hyperthermia (39°C-41°C) mimics fever, activating immune cells and raising metabolic rates. Intense heat above 50°C can release tumor antigens, enhancing immune reactions. Using photothermal nanoparticles for targeted heating and drug delivery can also modulate the immune response. Hyperthermia emerges as a cost-effective and well-tolerated adjuvant therapy when integrated with immunotherapy. This comprehensive review serves as a valuable resource for the selection of patient-specific treatments and the guidance of future experimental studies.

L-cystathionine protects against oxidative stress and DNA damage induced by oxidized low-density lipoprotein in THP-1-derived macrophages

Introduction: Oxidative stress in monocyte-derived macrophages is a significant pathophysiological process in atherosclerosis. L-cystathionine (L-Cth) acts as a scavenger for oxygen free radicals. However, the impact of L-Cth on macrophage oxidative stress during atherogenesis has remained unclear. This study aimed to investigate whether L-Cth affects oxidative stress in THP-1-derived macrophages and its subsequent effects on DNA damage and cell apoptosis. Methods: We established a cellular model of oxLDL-stimulated macrophages. The content of superoxide anion, H2O2, NO, and H2S in the macrophage were in situ detected by the specific fluorescence probe, respectively. The activities of SOD, GSH-Px, and CAT were measured by colorimetrical assay. The protein expressions of SOD1, SOD2, and iNOS were detected using western blotting. The DNA damage and apoptosis in the macrophage was evaluated using an fluorescence kit. Results: The results demonstrated that oxLDL significantly increased the content of superoxide anion and H2O2, the expression of iNOS protein, and NO production in macrophages. Conversely, oxLDL decreased the activity of antioxidants GSH-Px, SOD, and CAT, and downregulated the protein expressions of SOD1 and SOD2 in macrophages. However, treatment with L-Cth reduced the levels of superoxide anion, H2O2, and NO, as well as the protein expression of iNOS induced by oxLDL. Moreover, L-Cth treatment significantly enhanced GSH-Px, SOD, and CAT activity, and upregulated the expressions of SOD1 and SOD2 proteins in macrophages treated with oxLDL. Furthermore, both L-Cth supplementation and activation of endogenous L-Cth production suppressed DNA damage and cell apoptosis in oxLDL-injured macrophages, whereas inhibition of endogenous L-Cth exacerbated the deleterious effects of oxLDL. Conclusion: These findings suggest that L-Cth exerts a pronounced inhibitory effect on the oxidative stress, subsequent DNA damage and cell apoptosis in oxLDL-stimulated THP-1 monocytes. This study deepens our understanding of the pathogenesis of macrophage-related cardiovascular pathology.

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.

Synthesis, characterization, anticancer efficacy evaluation of ruthenium(II) and iridium(III) polypyridyl complexes toward A549 cells

A new ligand DFIP (2-(dibenzo[b,d]furan-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) and its two complexes iridium(III) [Ir(ppy)₂(DFIP)](PF₆) (ppy = 2-phenylpyridine, Ir1) and ruthenium(II) [Ru(bpy)₂(DFIP)](PF₆)₂ (bpy = 2,2'-bipyridine, Ru1) were synthesized and characterized. The anticancer effects of the two complexes on A549, BEL-7402, HepG2, SGC-7901, HCT116 and normal LO2 cells were tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Complex Ir1 shows high cytotoxic activity on A549, BEL-7402, SGC-7901 and HepG2, Ru1 exhibits moderate anticancer activity toward A549, BEL-7402 and SGC-7901 cells. The IC₅₀ values of Ir1 and Ru1 toward A549 are 7.2 ± 0.1 and 22.6 ± 1.4 μM, respectively. The localization of complexes Ir1 and Ru1 in the mitochondrial, intracellular accumulation of reactive oxygen species (ROS) levels, and the changes of mitochondrial membrane potential (MMP) and cytochrome c (cyto-c) were investigated. Apoptosis and cell cycle were detected by flow cytometry. Immunogenic cell death (ICD) was used to detect the effects of Ir1 and Ru1 on the A549 using a confocal laser scanning microscope. The expression of apoptosis-related proteins was detected by western blotting. Ir1 and Ru1 can increase the intracellular ROS levels and release cyto-c, reduce the MMP, leading to the apoptosis of A549 cells and blocking the A549 cells at the G0/G1 phase. Additionally, the complexes caused a decrease of the expression of polyADP-ribose polymerase (PARP), caspase 3, Bcl-2 (B-cell lymphoma-2), PI3K (phosphoinositide-3 kinase) and upregulated the expression of Bax. All these findings indicated that the complexes exert anticancer efficacy to induce cell death through immunogenic cell death, apoptosis, and autophagy.

Synthesis, biological evaluation of novel iridium(III) complexes targeting mitochondria toward melanoma B16 cells

A new ligand 2-(1E,3E,5E,7E)-2,6-dimethyl-8-(2,6,6-trimethylcyclohex-1-yl)octa-1,2,5,7-tetraen-1-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (DTOIP) was synthesized and combined with [Ir(ppy)₂Cl]₂·2H₂O (ppy = deprotonated Hppy: 2-phenylpyridine), [Ir(piq)₂Cl]₂·2H₂O (piq = deprotonated Hpiq: 1-phenylisoquinoline) and [Ir(bzq)₂Cl]₂·2H₂O (bzq = deprotonated Hbzq: benzo[h]quinolone) to form [Ir(ppy)₂(DTOIP)](PF₆) (Ir1), [Ir(piq)₂(DTOIP)](PF₆) (Ir2), and [Ir(bzq)₂(DTOIP)](PF₆) (Ir3), respectively. The complexes were characterized by elemental analysis, high-resolution mass spectrometry (HRMS), ¹H NMR and ¹³C NMR. The antiproliferative activity of the complexes toward B16, BEL-7402, Eca-109 and normal LO2 cells was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Complexes Ir1, Ir2 and Ir3 showed high antiproliferative activity against B16 cells with a low IC₅₀ values of 0.4 ± 0.1, 2.0 ± 0.1 and 1.4 ± 0.09 μM, respectively. Three-dimensional (3D) in vitro cell models also demonstrated that the iridium(III) complexes have a remarkable cytotoxicity to B16 cells. The experiments of cellular uptake, mitochondrial localization, and intracellular distribution of the drugs proved that the three iridium(III) complexes can enter the mitochondria, leading to the loss of mitochondrial membrane potential (MMP), decreased glutathione (GSH) levels, causing an increase of intracellular ROS content, and DNA damage, finally inducing apoptosis. RNA-sequence and bioinformatics analyses were used to analyze the differentially expressed genes and enriched biology processes. Antitumor in vivo demonstrated that complex Ir1 (5 mg/kg) exhibits a high efficacy to inhibit the tumor growth with an inhibitory rate of 71.67%. These results show that the complexes may be potent anticancer candidate drugs.