Mitochondrion-targeted platinum complexes suppressing lung cancer through multiple pathways involving energy metabolism

Inhibiting Glycolysis and Disrupting the Mitochondrial HK2-VDAC1 Protein-Protein Interaction Using a Bifunctional Lonidamine-Conjugated Metal Probe for Combating Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) relies primarily on aerobic glycolysis for energy and rapid cancer cell proliferation. Hexokinase 2 (HK2), a key enzyme regulating glycolysis, is overexpressed in TNBC, promoting tumor cell proliferation and apoptosis resistance by interacting with the mitochondrial membrane's voltage-dependent anion channel 1 (VDAC1). However, the development of bioactive molecules for effectively disrupting the HK2-VDAC1 interaction remains challenging. Herein, we have modified londamine (LND) with an iridium(III) complex to create bifunctional far-red probe 1. This complex not only has the ability to distinguish TNBC cells from normal cells by probing HK2 in mitochondria, but also significantly enhances antitumor activity by inhibiting mitochondrial glycolysis and effectively disrupting the HK2-VDAC1 interaction. This led to increased Bax-VDAC1 interaction, opening of the mitochondrial permeability transition pores (MPTPs), and generation of ROS, ultimately leading to mitochondrial dysfunction and enhanced cancer cell apoptosis. Probe 1 also demonstrated stronger antiproliferative activity than LND alone in a TNBC mouse model by targeting the HK2-VDAC1 interaction without causing overt toxicity. This work showcases the potential of probe 1 as an effective therapeutic agent for TNBC by inhibiting the mitochondrial HK2-VDAC1 interaction.

Pt(IV)-PROTAC Complexes with Synergistic Antitumor Activity and Enhanced Membrane Permeability

A class of Pt(IV)-PROTAC complexes was designed and synthesized with dual aims of inducing DNA strand damage and inhibiting DNA repair. These complexes showed good antiproliferative activity against a range of cancer cell lines. Enhanced intracellular uptake of platinum and PROTAC was observed. Multiple mechanisms of action were identified, including the induction of DNA damage, disruption of DNA repair, and activation of mitochondrial-dependent apoptosis. One of the Pt(IV)-PROTACs, CW-2, showed excellent antitumor activity in a xenograft mouse model. These results suggest that Pt(IV)-PROTAC represents a promising strategy for the development of novel antitumor therapeutics.

Drug delivery for platinum therapeutics

Cancer remains a severe threat to human health. Platinum drugs, such as cisplatin (CDDP), oxaliplatin, and carboplatin, are extensively utilized for treating various cancers and have become the primary drugs in first-line treatments for numerous solid tumors due to their effective anticancer properties. However, their side effects, including drug resistance, nephrotoxicity and ototoxicity, limit the clinical application. Therefore, there is an urgent need to develop targeted delivery and controlled release systems for platinum drugs to address the disadvantages, enhancing tumor accumulation and improving therapeutic effects. In this review, we first review the progress of platinum drugs, their anticancer mechanism, clinical applications and limitations. Then, we comprehensively summarize the platinum-based delivery using drug carriers and responsive strategies. We especially highlight the platinum-delivery formulations in ongoing clinical trials. Finally, we provide perspectives for this field. The review could provide an increasingly in-depth understanding of platinum therapeutics and motivate increasing delivery tactics to overcome the limitations of platinum application.

Ruthenium(II)-mercapto complexes induce cell damage via apoptosis pathway on ovarian cancer cells

Ovarian cancer represents a leading cause of cancer-related deaths in women worldwide. Chemotherapeutic agents are usually employed to treat the patients, and Ruthenium(II)-based compounds have been investigated as possible substitutes for platinum drugs. In this work, we studied three different Ru(II)-phosphine-mercapto complexes (1-3) as potential cytotoxic agents against A2780 and A2780-cisR ovarian cancer cells. A time-dependent cytotoxicity was observed for 2, which also exhibited better selectivity than cisplatin control. A similar cytotoxic behavior was observed on 3D tumor spheroids. Although no changes were observed in cell cycle distribution, compound 2 affected the mitochondrial membrane potential on A2780 cells, and caused cell death via apoptotic pathway, which was confirmed by flow cytometry assay. Western blotting experiments revealed that 2 affected the expression of p53, PCNA, γH2AX and cleaved caspase-3, making it a promising anticancer agent for ovarian cancer.

Carrier-Free Cisplatin-Dactolisib Nanoparticles for Enhanced Synergistic Antitumor Efficacy

Cisplatin (CDDP) is one of the most commonly used chemotherapeutic agents for solid tumors and hematologic malignancy. However, its therapeutic outcomes have remained unsatisfactory due to severe side effects, a short elimination half-life, the emergence of drug resistance, and the induction of metastasis. Combination with other chemotherapeutic agents has been proposed as one strategy to address the drawbacks of CDDP-based therapy. Therefore, this study aimed to boost the antitumor efficacy of cisplatin (CDDP) with a PI3K/mTOR dual inhibitor, dactolisib (BEZ), via a carrier-free codelivery system based on the self-assembly of the coordinated CDDP-BEZ. The synthesized CDDP-BEZ nanoparticles (NPs) possess sensitive pH-responsiveness, facilitating the delivery of both drugs to cancer cells. CDDP-BEZ NPs specifically enhanced cytotoxicity in cancer cells due to the synergy between cisplatin and dactolisib, resulting in augmented DNA damage, activation of mitochondria-dependent apoptosis, and increased inhibition on the PI3K/mTOR signaling axis. The inhibition of tumor migration and metastasis by CDDP-BEZ NPs was observed both in vitro and in vivo. Our data suggest that CDDP-BEZ NPs could serve as a safe and effective platform to maximize the synergy between both drugs in combating cancer, presenting a strategy to promote the therapeutic efficacy of platinum-based chemotherapeutic agents by combining them with PI3K inhibitors.

Triphenylphosphine-modified cyclometalated iridiumIII complexes as mitochondria-targeting anticancer agents with enhanced selectivity

This study presents the development and evaluation of triphenylphosphine-modified cyclometalated iridiumIII complexes as selective anticancer agents targeting mitochondria. By leveraging the mitochondrial localization capability of the triphenylphosphine group, these complexes displayed promising cytotoxicity in the micromolar range (3.12-7.24 μM) against A549 and HeLa cancer cells, these complexes exhibit significantly higher activity compared to their unmodified counterparts lacking the triphenylphosphine moiety. Moreover, they demonstrate improved specificity for cancer cells over normal cells, achieving selectivity index in the range of 5.46-14.83. Mechanistic studies confirmed that these complexes selectively target mitochondria rather than DNA, as shown by confocal microscopy and flow cytometry, where they accumulate to induce mitochondrial dysfunction. This disruption leads to mitochondrial membrane depolarization (MMP), elevated reactive oxygen species (ROS) levels, and activation of intrinsic apoptosis pathways. Furthermore, the complexes induce cell cycle arrest at the G2/M phase and suppress the migration of A549 cells.

A PVP-stabilized cerium oxide-platinum nanocomposite synthesized in TEG: pro-/antioxidant activities

Cerium oxide nanoparticles (CeNPs) represent a highly promising material for a number of chemical and biological applications involving oxidation-reduction processes. However, the impact of synthesis conditions, as well as the incorporation of synergistic agents of a different catalytic nature, on the antioxidant or prooxidant properties of CeNPs remains a subject of ongoing investigation. In this study, non-stoichiometric CeNPs (∼10% Ce3+) stabilized by polyvinylpyrrolidone (PVP) were synthesized through the thermal autoxidative decomposition of cerium(iii) nitrate in a high-boiling glycol. A novel approach for the synthesis of CeNPs in the absence of additives (PVP-CeNPs) and with platinum (PVP-CeNPs-Pt), followed by the formation of platinum nanoparticles (PVP-PtNPs), was employed in a stepwise one-pot process. In chemical tests, the PVP-CeNPs-Pt nanocomposite exhibited enhanced peroxidase-mimicking activity and accelerated the Fenton-type reaction of dye decolorization. Nevertheless, it was found to have the ability to reduce adrenaline autoxidation via the superoxide dismutase-mimicking pathway. In vitro studies demonstrated that PVP-CeNPs and PVP-CeNPs-Pt enhanced H2O2-induced oxytosis while restoring cellular metabolic activity inhibited by the Fenton-like pathway of cellular apoptosis (ferroptosis) initiated by sulfasalazine. The authors suggest that the oxidoreductase activity of CeNP-based systems in the chemical tests and in biological processes in vitro may be caused by different mechanisms, which are discussed.

Cytotoxic Ruthenium(II)-Diphosphine Complexes Affect the Mitochondrial Respiration of Lung Cancer Cells

In this work, we studied six Ruthenium(II)-diphosphine compounds containing different mercapto ligands (N-S), with general formula [Ru(N-S)(dppm)2]Cl (dppm=1,1-bis(diphenylphosphino)methane). These compounds were characterized by several techniques (NMR [1H, 31P(1H), and 13C], HRMS, IR, UV-Vis and XRD) and their purity confirmed by elemental analysis. DLS experiments revealed low diameters and polydispersity indexes, and positive log P values in n-octanol/PBS indicated their preference for the organic phase. In general, these compounds are stable in different media over 48 h. Cytotoxicity experiments revealed promising IC50 values on A549 breast cancer cells, 0.48 μM and 0.80 μM for [Ru(mtz)(dppm)2]Cl (1) and [Ru(mmi)(dppm)2]Cl (2), respectively (mtz and mmi are 2-mercapto-2-thiazoline and mercapto-1-methylimidazole in their deprotonated form, respectively). Clonogenic and migration experiments indicated their antiproliferative and anti-migratory capacity. ICP-MS results indicated their cellular accumulation in the nucleus, with little amounts in mitochondria. No covalent DNA binding was observed by ICP-MS. JC-1 and cell Mito Stress test confirmed mitochondrial dysfunction, which was verified by mitochondrial membrane potential uncoupling and drastic alterations in the oxygen consumption rate. Taken together, our results provide crucial insights regarding the anticancer potential of ruthenium(II)-phosphine compounds.

Photodynamic therapy photosensitizers and photoactivated chemotherapeutics exhibit distinct bioenergetic profiles to impact ATP metabolism

Energy is essential for all life, and mammalian cells generate and store energy in the form of ATP by mitochondrial (oxidative phosphorylation) and non-mitochondrial (glycolysis) metabolism. These processes can now be evaluated by extracellular flux analysis (EFA), which has proven to be an indispensable tool in cell biology, providing previously inaccessible information regarding the bioenergetic landscape of cell lines, complex tissues, and in vivo models. Recently, EFA demonstrated its utility as a screening tool in drug development, both by providing insights into small molecule-organelle interactions, and by revealing the peripheral and potentially undesired off-target effects small molecules have within cells. Surprisingly, technologies to quantify cellular bioenergetics have not been systematically applied in phototherapy development, leaving open several questions about how the mechanism of action of a compound can impact essential cellular functions. Here, we utilized the Seahorse analyzer to address this question for photosensitizers (PSs) for photodynamic therapy (PDT) and contrast these systems to molecules that photo-release a ligand and thus act as photocages or photoactivated chemotherapeutics (PACT), intending to understand the influence these two classes of compounds have on cellular bioenergetics. EFA results show that acute treatment of A549 lung adenocarcinoma cells with PDT agents induces a quiescent bioenergetic response as a result of mitochondrial respiration shutdown. The loss of oxidative phosphorylation is followed by disruption of glycolysis, which occurs after an initial increase in glycolytic respiration is unable to compensate for the interruption of the electron transport chain (ETC). In contrast, the PACT agents tested had little impact on cellular respiration, and the minor inhibition of these metabolic processes was not related to the mechanism of action, as reflected by a lack of correlation with photoejection efficiency. Notably, a system capable of both generating 1O2 and photo-releasing a ligand exhibited the dominant profile of a PDT agent and induced the quiescent bioenergetic state, indicating potential implications on cellular bioenergetics for so-called dual-action agents. These findings are presented with the aim to provide the necessary groundwork for expanding the application and utility of EFA to phototherapeutics and to highlight the role of metabolic alterations in PDT.

Hydrazone copper(II) complexes suppressed lung adenocarcinoma by activating multiple anticancer pathway

Activating multiple anti-cancer pathways has great potential for tumor treatment. Herein, we synthesized two binuclear Cu(II) hydrazone complexes ([Cu2(HL1)2Cl2] 1 and [Cu2(HL1)2Br2] 2) and two mononuclear hydrazone-Cu(II) complexes ([Cu(HL2)Cl]·CH3OH 3 and [Cu(HL2)(H2O)Br]·2H2O 4), to evaluate their anti-lung cancer activities. MTT assays revealed that the Cu(II) complexes demonstrate superior anticancer activity compared to cisplatin. Among them, complex 3 exhibited selective toxicity towards A549 cancer cells in comparison to normal cells and demonstrated hemolytic activity comparable to cisplatin. The low toxicity and effective antitumor capabilities of complex 3 have been confirmed in xenograft experiments using A549 tumor-bearing mice. Interestingly, complex 3 eradicates lung tumor cells both in vivo and in vitro by initiating multiple anticancer pathways, including cuproptosis. Our research extends the study of hydrazone copper complexes and provides strategies for the treatment of lung cancer.

Triphenylphosphine-Modified IridiumIII, RhodiumIII, and RutheniumII Complexes to Achieve Enhanced Anticancer Selectivity by Targeting Mitochondria

The incorporation of an organelle-targeting moiety into compounds has proven to be an effective strategy in the development of targeted anticancer drugs. We herein report the synthesis, characterization, and biological evaluation of novel triphenylphosphine-modified half-sandwich iridiumIII, rhodiumIII, and rutheniumII complexes. The primary goal was to enhance anticancer selectivity through mitochondrial targeting. All these triphenylphosphine-modified complexes exhibited promising cytotoxicity in the micromolar range (5.13-23.22) against A549 and HeLa cancer cell lines, surpassing the activity of comparative complexes that lack the triphenylphosphine moiety. Noteworthy is their good selectivity toward cancer cells compared to normal BEAS-2B cells, underscored by selectivity index ranging from 7.3 to >19.5. Mechanistically, these complexes primarily target mitochondria rather than interacting with DNA. The targeting of mitochondria and triggering mitochondrial dysfunction were confirmed using both confocal microscopy and flow cytometry. Their ability to depolarize mitochondrial membrane potential (MMP) and enhance reactive oxygen species (ROS) was observed, thereby leading to intrinsic apoptotic pathways. Moreover, these complexes lead to cell cycle arrest in the G2/M phase and demonstrated antimigration effects, significantly inhibiting the migration of A549 cells in wound-healing assays.

Design and synthesis of novel mitochondria-targeted ergosterol peroxide derivatives as potential anti-cancer agents

Ergosterol peroxide (EP) is a natural steroid compound that has been reported to have significant antitumor activity. However, its poor water solubility and cellular uptake mean that it has weak efficacy against tumor cells. Herein, we designed and synthesized a series of EP derivatives with mitochondrial targeting properties. Of these, compound 15a showed an IC50 value of 0.32 μM against MCF-7 cells, which was 67-fold higher than that of the parental EP (IC50 = 21.46 μM), and was better than cisplatin (IC50 = 4.23 μM), had a selectivity index of 25.28 (IC50MCF-10A/IC50MCF-7). Additionally, compound 15a promoted an increase in intracellular reactive oxygen species levels and a decrease in mitochondrial membrane potential, and blocked the cell cycle in the G0/G1 phase. In a mouse model of breast cancer, 15a showed 89.85 % tumor inhibition at a dose of 20 mg/kg, which is similar to the therapeutic effect of the cisplatin. On the basis of these results, 15a could be considered for further preclinical evaluation for cancer therapy.

Developing a Rhodium(III) Complex to Reprogram the Tumor Immune and Metabolic Microenvironments: Overcoming Multidrug Resistance and Metastasis in Non-Small Cell Lung Cancer

To effectively inhibit the growth and metastasis of non-small cell lung cancer (NSCLC) and overcome its multidrug resistance (MDR), we designed and synthesized a series of rhodium (Rh, III) 2-benzoylpyridine thiosemicarbazone complexes. Through studying their structure-activity relationships, we identified the Rh(III) complex (Rh4) with excellent cytotoxicity against multidrug-resistant lung cancer cells (A549/ADR cells). Additionally, we successfully constructed an apoferritin (AFt) nanoparticle (NP) delivery system (AFt-Rh4 NPs). Importantly, AFt-Rh4 NPs not only exhibited excellent antitumor and antimetastatic capabilities against multidrug-resistant NSCLC in vivo but also demonstrated enhanced targeting ability and reduced systemic toxicity and adverse effects. Furthermore, we confirmed and elucidated the mechanisms by which Rh4/AFt-Rh4 NPs inhibit tumor metastasis and reverse MDR in NSCLC. This was achieved by reprogramming the immune and metabolic tumor microenvironments through induction of immunogenic cell death and inhibition of dual-energy metabolism.

Lysosome-targeted cyclometalated Ir(III) complexes as photosensitizers/photoredox catalysts for cancer therapy

A novel lysosome-targeted photosensitizer/photoredox catalyst based on cyclometalated Ir(III) complex IrL has been designed and synthesized, which exhibited excellent phosphorescence properties and the ability to generate single oxygen (1O2) and photocatalytically oxidize 1,4-dihydronicotinamide adenine dinucleotide (NADH) under light irradiation. Most importantly, the aforementioned activities are significantly enhanced due to protonation under acidic conditions, which makes them highly attractive in light-activated tumor therapy, especially for acidic lysosomes and tumor microenvironments. The photocytotoxicity of IrL and the mechanism of cell death have been investigated. Additionally, the tumor-killing ability of IrL under light irradiation was evaluated using a 4T1 tumor-bearing mouse model. This work provides a strategy for the development of lysosome-targeted photosensitizers/photoredox catalysts to overcome hypoxic tumors.

Co-exposure of polystyrene nanoplastics and copper induces development toxicity and intestinal mitochondrial dysfunction in vivo and in vitro

Nanoplastics (NPs) have raised concerns about the combined toxicity to living organisms due to their ability to adsorb heavy metals. There is still uncertainty, however, whether NPs combined with heavy metals exert adverse effects on intestinal microenvironment, especially the intestinal cells and microbiota. Herein, the combined effects of 500 nm spherical-shaped polystyrene nanoplastics (PSNPs) and copper ions (Cu2+) on intestinal cells and gut microbiota were assessed using HCT-116 cells and zebrafish models. The combined exposure of PSNPs (10 mg/L) and Cu2+ (0.5 mg/L) induced more severer hatching interference of zebrafish embryos, deformation, and mortality. In larval stage, PSNPs (10 mg/L) accumulated and carried more Cu2+ in the gastrointestinal tract (GIT) of zebrafish after co-exposure for 5 days. Excessive neutrophil recruitment and oxidative stress in GIT of zebrafish larvae were observed. The mechanism of the combined toxicity was revealed by transmission electron microscopy (TEM) showing the injuries of GIT, transcriptome and 16S rDNA gene sequencing showing the toxicity pathways, including oxidative phosphorylation and respiratory electron transport chain, as well as microbial community analysis showing the induced microbiota dysbiosis. In vitro tests using HCT-116 cells showed that PSNPs (10 mg/L) and Cu2+ (0.5 mg/L) increased cell death while decreasing ATP concentration and mitochondrial membrane potential after 48 h exposure. These findings may provide new insights into the combined toxicity of nanoplastics and heavy metals in the intestinal microenvironment.

Thiosemicarbazone Mixed-Valence Cu(I/II) Complex against Lung Adenocarcinoma Cells through Multiple Pathways Involving Cuproptosis

Induction of cuproptosis and targeting of multiple signaling pathways show promising applications in tumor therapy. In this study, we synthesized two thiosemicarbazone-copper complexes ([CuII(L)Cl] 1 and [CuII2CuI(L)2Cl3] 2, where HL is the (E)-N-methyl-2-(phenyl(pyridin-2-yl)methylene ligand), to assess their antilung cancer activities. Both copper complexes showed better anticancer activity than cisplatin and exhibited hemolysis comparable to that of cisplatin. In vivo experiments showed that complex 2 retarded the A549 cell growth in a mouse xenograft model with low systemic toxicity. Primarily, complex 2 kills lung cancer cells in vitro and in vivo by triggering multiple pathways, including cuproptosis. Complex 2 is the first mixed-valent Cu(I/II) complex to induce cellular events consistent with cuproptosis in cancer cells, which may stimulate the development of mixed-valent copper complexes and provide effective cancer therapy.

The Influence of the Auxiliary Ligand in Monofunctional Pt(II) Anticancer Complexes on the DNA Backbone

Monofunctional platinum complexes offer a promising alternative to cisplatin in cancer chemotherapy, showing a unique mechanism of action. Their ability to induce minor helix distortions effectively inhibits DNA transcription. In our study, we synthesized and characterized three monofunctional Pt(II) complexes with the general formula [Pt(en)(L)Cl]NO3, where en = ethylenediamine, and L = pyridine (py), 2-methylpyridine (2-mepy), and 2-phenylpyridine (2-phpy). The hydrolysis rates of [Pt(en)(py)Cl]NO3 (1) and [Pt(en)(2-mepy)Cl]NO3 (2) decrease with the bulkiness of the auxiliary ligand with k(1) = 2.28 ± 0.15 × 10-4 s-1 and k(2) = 8.69 ± 0.98 × 10-5 s-1 at 298 K. The complex [Pt(en)(2-phpy)Cl]Cl (3) demonstrated distinct behavior. Upon hydrolysis, an equilibrium (Keq = 0.385 mM) between the complexes [Pt(en)(2-phpy)Cl]+ and [Pt(en)(2-phpy-H+)]+ was observed with no evidence (NMR or HR-ESI-MS) for the presence of the aquated complex [Pt(en)(2-phpy)(H2O)]2+. Despite the kinetic similarities between phenanthriplatin and (2), complexes (1) and (2) exhibit minimal activity against A549 lung cancer cell line (IC50 > 100 μΜ), whereas complex (3) exhibits notable cytotoxicity (IC50 = 41.11 ± 2.1 μΜ). In examining the DNA binding of (1) and (2) to the DNA model guanosine (guo), we validated their binding through guoN7, which led to an increased population of the C3'-endo sugar conformation, as expected. However, we observed that the rapid transition 2E (C2'-endo) ↔ 3E (C3'-endo), in the case of [Pt(en)(py)(guo)](NO3)2 ([1-guo]), slows down in the case of [Pt(en)(2-mepy)(guo)](NO3)2 ([2-guo]), resulting in separate signals for the two conformers in the 1H NMR spectra. This phenomenon arises from the steric hindrance between the methyl group of pyridine and the sugar moiety of guanosine. Notably, this hindrance is absent in [2-(9-MeG)] (9-MeG = 9-methylguanine), probably due to the absence of a bulky sugar unit in 9-MeG. In the case of (3), where the bulkiness of the substitution on the pyridine is further increased by a phenyl group, we observed a notable proximity between 9-MeGH8 and the phenyl ring of 2-phpy. Considering that only (3) exhibited good cytotoxicity against the A549 cancer cell line, it is suggested that auxiliary ligands, L, with an extended aromatic system and proper orientation in complexes of the type cis-[Pt(en)(L)Cl]NO3, may enhance the cytotoxic activity of such complexes.

Anticancer activity of 8-hydroxyquinoline-triphenylphosphine rhodium(III) complexes targeting mitophagy pathways

Metallodrugs exhibiting distinct mechanisms of action compared with cisplatin hold promise for overcoming cisplatin resistance and improving the efficacy of anticancer drugs. In this study, a new series of rhodium (Rh)(III) complexes containing tris(triphenylphosphine)rhodium(I) chloride [(TPP)3RhCl] (TPP = triphenylphosphine, TPP=O = triphenylphosphine oxide) and 8-hydroxyquinoline derivatives (H-XR1-H-XR4), namely [Rh(XR1)2(TPP)Cl]·(TPP=O) (Yulin Normal University-1a [YNU-1a]), [Rh(XR2)2(TPP)Cl] (YNU-1b), [Rh(XR3)2(TPP)Cl] (YNU-1c), and [Rh(XR4)2(TPP)Cl] (YNU-1d), was synthesized and characterized via X-ray diffraction, mass spectrometry and IR. The cytotoxicity of the compounds YNU-1a-YNU-1d in Hep-G2 and HCC1806 human cancer cell lines and normal HL-7702 cell line was evaluated. YNU-1c exhibited cytotoxicity and selectivity in HCC1806 cells (IC50 = 0.13 ± 0.06 μM, selectivity factor (SF) = 384.6). The compounds YNU-1b and YNU-1c, which were selected for mechanistic studies, induced the activation of apoptotic pathways and mitophagy. In addition, these compounds released cytochrome c, cleaved caspase-3/pro-caspase-3 and downregulated the levels of mitochondrial respiratory chain complexes I/IV (M1 and M4) and ATP. The compound YNU-1c, which was selected for in vivo experiments, exhibited tumor growth inhibition (58.9 %). Importantly, hematoxylin and eosin staining and TUNEL revealed that HCC1806 tumor tissues exhibited significant apoptotic characteristics. YNU-1a-YNU-1d compounds are promising drug candidates that can be used to overcome cisplatin resistance.

TPP-based conjugates: potential targeting ligands

Mitochondria are one of the major sources of energy as well as regulators of cancer cell metabolism. Thus, they are potential targets for the effective treatment and management of cancer. Research has explored triphenylphosphonium (TPP) derivatives as potent cancer-targeting ligands because of their lipophilic nature and mitochondrial affinity. In this review, we summarize the utility of TPP-based conjugates targeting mitochondria in different types of cancer and other diseases, such as neurodegenerative and cardiovascular disorders. Such conjugates offer versatile therapeutic potential by modulating membrane potential, influencing reactive oxygen species (ROS) production, and coupling of molecular modifications (such as ATP metabolism and energy metabolism). Thus, we highlight TPP conjugates as promising mitochondria-targeting agents for use in targeted drug delivery systems.

A G-quadruplex-binding platinum complex induces cancer mitochondrial dysfunction through dual-targeting mitochondrial and nuclear G4 enriched genome

BACKGROUND

G-quadruplex DNA (G4) is a non-canonical structure forming in guanine-rich regions, which play a vital role in cancer biology and are now being acknowledged in both nuclear and mitochondrial (mt) genome. However, the impact of G4-based targeted therapy on both nuclear and mt genome, affecting mt function and its underlying mechanisms remain largely unexplored.

METHODS

The mechanisms of action and therapeutic effects of a G4-binding platinum(II) complex, Pt-ttpy, on mitochondria were conducted through a comprehensive approaches with in vitro and in vivo models, including ICP-MS for platinum measurement, PCR-based genetic analysis, western blotting (WB), confocal microscope for mt morphology study, extracellular flux analyzer, JC1 and Annexin V apoptosis assay, flow cytometry and high content microscope screening with single-cell quantification of both ROS and mt specific ROS, as well as click-chemistry for IF study of mt translation. Decipher Pt-ttpy effects on nuclear-encoded mt related genes expression were undertaken via RNA-seq, Chip-seq and CUT-RUN assays.

RESULTS

Pt-ttpy, shows a highest accumulation in the mitochondria of A2780 cancer cells as compared with two other platinum(II) complexes with no/weak G4-binding properties, Pt-tpy and cisplatin. Pt-ttpy induces mtDNA deletion, copy reduction and transcription inhibition, hindering mt protein translation. Functional analysis reveals potent mt dysfunction without reactive oxygen species (ROS) induction. Mechanistic study provided first evidence that most of mt ribosome genes are highly enriched in G4 structures in their promoter regions, notably, Pt-ttpy impairs most nuclear-encoded mt ribosome genes' transcription through dampening the recruiting of transcription initiation and elongation factors of NELFB and TAF1 to their promoter with G4-enriched sequences. In vivo studies show Pt-ttpy's efficient anti-tumor effects, disrupting mt genome function with fewer side effects than cisplatin.

CONCLUSION

This study underscores Pt-ttpy as a G4-binding platinum(II) complex, effectively targeting cancer mitochondria through dual action on mt and nuclear G4-enriched genomes without inducing ROS, offering promise for safer and effective platinum-based G4-targeted cancer therapy.

Mitochondria-targeted BODIPY dyes for small molecule recognition, bio-imaging and photodynamic therapy

Mitochondria are essential for a diverse array of biological functions. There is increasing research focus on developing efficient tools for mitochondria-targeted detection and treatment. BODIPY dyes, known for their structural versatility and excellent spectroscopic properties, are being actively explored in this context. Numerous studies have focused on developing innovative BODIPYs that utilize optical signals for imaging mitochondria. This review presents a comprehensive overview of the progress made in this field, aiming to investigate mitochondria-related biological events. It covers key factors such as design strategies, spectroscopic properties, and cytotoxicity, as well as mechanism to facilitate their future application in organelle imaging and targeted therapy. This work is anticipated to provide valuable insights for guiding future development and facilitating further investigation into mitochondria-related biological sensing and phototherapy.

Designing a Mitochondria-Targeted Theranostic Cyclometalated Iridium(III) Complex: Overcoming Cisplatin Resistance and Inhibiting Tumor Metastasis through Necroptosis and Immune Response

To develop a potential theranostic metal agent to reverse the resistance of cancer cells to cisplatin and effectively inhibit tumor growth and metastasis, we proposed to design a cyclometalated iridium (Ir) complex based on the properties of the tumor environment (TME). To the end, we designed and synthesized a series of Ir(III) 2-hydroxy-1-naphthaldehyde thiosemicarbazone complexes by modifying the hydrogen atom(s) of the N-3 position of 2-hydroxy-1-naphthaldehyde thiosemicarbazone compounds and the structure of cyclometalated Ir(III) dimers and then investigated their structure-activity and structure-fluorescence relationships to obtain an Ir(III) complex (Ir5) with remarkable fluorescence and cytotoxicity to cancer cells. Ir5 not only possesses mitochondria-targeted properties but also overcomes cisplatin resistance and effectively inhibits tumor growth and metastasis in vivo. Besides, we confirmed the anticancer mechanisms of Ir5 acting on different components in the TME: directly killing liver cancer cells by inducing necroptosis and activating the necroptosis-related immune response.

Recently Reported Biological Activities and Action Targets of Pt(II)- and Cu(II)-Based Complexes

Most diseases that affect human beings across the world are now treated with drugs of organic origin. However, some of these are associated with side effects, toxicity, and resistance phenomena. For the treatment of many illnesses, the development of new molecules with pharmacological potential is now an urgent matter. The biological activities of metal complexes have been reported to have antitumor, antimicrobial, anti-inflammatory, anti-infective and antiparasitic effects, amongst others. Metal complexes are effective because they possess unique properties. For example, the complex entity possesses the effective biological activity, then the formation of coordination bonds between the metal ions and ligands is controlled, metal ions provide it with extraordinary mechanisms of action because of characteristics such as d-orbitals, oxidation states, and specific orientations; metal complexes also exhibit good stability and good physicochemical properties such as water solubility. Platinum is a transition metal widely used in the design of drugs with antineoplastic activities; however, platinum is associated with side effects which have made it necessary to search for, and design, novel complexes based on other metals. Copper is a biometal which is found in living systems; it is now used in the design of metal complexes with biological activities that have demonstrated antitumoral, antimicrobial and anti-inflammatory effects, amongst others. In this review, we consider the open horizons of Cu(II)- and Pt(II)-based complexes, new trends in their design, their synthesis, their biological activities and their targets of action.

Aerobic Exercise Improves Radiation Therapy Efficacy in Non-Small Cell Lung Cancer: Preclinical Study Using a Xenograft Mouse Model

The "oxygen effect" improves radiation efficacy; thus, tumor cell oxygen concentration is a crucial factor for improving lung cancer treatment. In the current study, we aimed to identify aerobic exercise-induced changes in oxygen concentrations in non-small cell lung cancer (NSCLC) cells. To this end, an NSCLC xenograft mouse model was established using human A549 cells. Animals were subsequently subjected to aerobic exercise and radiation three times per week for 2 weeks. Aerobic exercise was performed at a speed of 8.0 m/m for 30 min, and the tumor was irradiated with 2 Gy of 6 MV X-rays (total radiation dose 12 Gy). Combined aerobic exercise and radiation reduced NSCLC cell growth. In addition, the positive effect of aerobic exercise on radiation efficacy through oxygenation of tumor cells was confirmed based on hypoxia-inducible factor-1 and carbonic anhydrase IX expression. Finally, whole-transcriptome analysis revealed the key factors that induce oxygenation in NSCLC cells when aerobic exercise was combined with radiation. Taken together, these results indicate that aerobic exercise improves the effectiveness of radiation in the treatment of NSCLC. This preclinical study provides a basis for the clinical application of aerobic exercise to patients with NSCLC undergoing radiation therapy.

Advances in Small-Molecule Fluorescent pH Probes for Monitoring Mitophagy

Mitochondria play a crucial role in regulating cellular energy homeostasis and cell death, making them essential organelles. Maintaining proper cellular functions relies on the removal of damaged mitochondria through a process called mitophagy. Mitophagy is associated with changes in the pH value and has implications for numerous diseases. To effectively monitor mitophagy, fluorescent probes that exhibit high selectivity and sensitivity based on pH detection have emerged as powerful tools. In this review, we present recent advancements in the monitoring of mitophagy using small-molecule fluorescence pH probes. We focus on various sensing mechanisms employed by these probes, including intramolecular charge transfer (ICT), fluorescence resonance energy transfer (FRET), through bond energy transfer (TBET), and photoelectron transfer (PET). Additionally, we discuss disease models used for studying mitophagy and summarize the design requirements for small-molecule fluorescent pH probes suitable for monitoring the mitophagy process. Lastly, we highlight the remaining challenges in this field and propose potential directions for the future development of mitophagy probes.

A novel benzothiazole-based mononuclear platinum(II) complex displaying potent antiproliferative activity in HepG-2 cells via mitochondrial-mediated apoptosis

A novel mononuclear platinum(II) complex, [Pt(L-H)Cl] (1, where L= N-(4-(benzo[d]thiazol-2-yl)phenyl)-2-((2-pyridylmethyl)(2-hydroxyethyl)-amino)acetamide), was obtained by covalently tethering a benzothiazole derivative 2-(4-aminophenyl)benzothiazole to the 2-pyridylmethyl-2-hydroxyethylamine chelating PtII center. In vitro tests indicated that complex 1 displayed excellent antiproliferative activity against the tested cancer cell lines, especially liver cancer HepG-2 and SMMC-7221 cells. Importantly, the complex possessed 4.33-fold higher antiproliferative activity as compared with cisplatin against HepG-2 cells, but was less toxic to the normal cell line L02 with the selectivity index (SI = IC50(L02)/IC50(HepG-2)) value of 8.36 compared to cisplatin (SI, 1.40). The results suggested that 1 might have the potential to act as a candidate for the treatment of hepatocellular carcinoma (HCC). Cellular uptake and distribution studies showed that 1 could effectively pass through the membrane of cells, enter the nuclei and mitochondria, induce the platination of cellular DNA. The interaction of 1 with CT-DNA demonstrated that 1 could effectively bind to DNA in a dual binding mode, i.e., the intercalation of the 2-(4-aminophenyl)benzothiazole unit plus monofunctional platination of the platinum(II) moiety. In addition, Hoechst 33342 staining and flow cytometry analysis illustrated that 1 arrested the cell cycle in HepG-2 cancer cells at G2/M phases, induced mitochondrial membrane depolarization, increased ROS generation, and caused obvious cell apoptosis. Further cellular mechanism studies elucidated that 1 triggered HepG-2 cell apoptosis via the mitochondrial-mediated pathway by upregulating the gene and protein expression levels of Bax, downregulating the gene and protein expression levels of Bcl-2, and activating the caspase cascade.

Copper(II) complexes with plumbagin and bipyridines target mitochondria for enhanced chemodynamic cancer therapy

The combination of mitochondrial targeting and chemodynamic therapy is a promising anti-cancer strategy. Three mitochondria targeting copper(II) complexes (Cu1-Cu3) with plumbagin and bipyridine ligands for enhanced chemodynamic therapy were synthesized and characterized. Their anti-proliferative activity to HeLa cells was higher than that of cisplatin, and their toxicity to normal cells was low. Cellular uptake and distribution studies indicated that Cu1 and Cu3 were mainly accumulated in mitochondria. The mechanism studies showed that Cu1 and Cu3 converted intracellular H2O2 into toxic hydroxyl radicals by consuming glutathione, leading to mitochondrial dysfunction. Treatment with the copper complex caused ER stress and cell arrest in the S phase which resulted in apoptosis. In vivo, Cu1 and Cu3 effectively inhibited the growth of HeLa xenograft tumors without obvious toxic and side effects.

Targeting cancer stem cell OXPHOS with tailored ruthenium complexes as a new anti-cancer strategy

BACKGROUND

Previous studies by our group have shown that oxidative phosphorylation (OXPHOS) is the main pathway by which pancreatic cancer stem cells (CSCs) meet their energetic requirements; therefore, OXPHOS represents an Achille's heel of these highly tumorigenic cells. Unfortunately, therapies that target OXPHOS in CSCs are lacking.

METHODS

The safety and anti-CSC activity of a ruthenium complex featuring bipyridine and terpyridine ligands and one coordination labile position (Ru1) were evaluated across primary pancreatic cancer cultures and in vivo, using 8 patient-derived xenografts (PDXs). RNAseq analysis followed by mitochondria-specific molecular assays were used to determine the mechanism of action.

RESULTS

We show that Ru1 is capable of inhibiting CSC OXPHOS function in vitro, and more importantly, it presents excellent anti-cancer activity, with low toxicity, across a large panel of human pancreatic PDXs, as well as in colorectal cancer and osteosarcoma PDXs. Mechanistic studies suggest that this activity stems from Ru1 binding to the D-loop region of the mitochondrial DNA of CSCs, inhibiting OXPHOS complex-associated transcription, leading to reduced mitochondrial oxygen consumption, membrane potential, and ATP production, all of which are necessary for CSCs, which heavily depend on mitochondrial respiration.

CONCLUSIONS

Overall, the coordination complex Ru1 represents not only an exciting new anti-cancer agent, but also a molecular tool to dissect the role of OXPHOS in CSCs. Results indicating that the compound is safe, non-toxic and highly effective in vivo are extremely exciting, and have allowed us to uncover unprecedented mechanistic possibilities to fight different cancer types based on targeting CSC OXPHOS.

Improving In Vivo Tumor Accumulation and Efficacy of Platinum Antitumor Agents by Electronic Tuning of the Kinetic Lability

The impact of kinetic lability or reactivity on in vitro cytotoxicity, stability in plasma, in vivo tumor and tissue accumulation, and antitumor efficacy of functional platinum(II) (Pt) anticancer agents containing a O˄O β-diketonate leaving ligand remain largely unexplored. To investigate this, we synthesized Pt complexes [(NH3 )2 Pt(L1-H)]NO3 and [(DACH)Pt(L1-H)]NO3 (L1=4,4,4-trifluoro-1-ferrocenylbutane-1,3-dione, DACH=1R,2R-cyclohexane-1,2-diamine) containing an electron deficient [L1-H]- O˄O leaving ligand and [(NH3 )2 Pt(L2-H)]NO3 and [(DACH)Pt(L2-H)]NO3 (L2=1-ferrocenylbutane-1,3-dione) containing an electron-rich [L2-H]- O˄O leaving ligand. While all four complexes have comparable lipophilicity, the presence of the electron-withdrawing CF3 group was found to dramatically enhance the reactivity of these complexes toward nucleophilic biomolecules. In vitro cellular assays revealed that the more reactive complexes have higher cellular uptake and higher anticancer potency as compared to their less reactive analogs. But the scenario is opposite in vivo, where the less reactive complex showed improved tissue and tumor accumulation and better anticancer efficacy in mice bearing ovarian xenograft when compared to its more reactive analog. Finally, in addition to demonstrating the profound but contrasting impact of kinetic lability on in vitro and in vivo antitumor potencies, we also described the impact of kinetic lability on the mechanism of action of this class of promising antitumor agents.

Mitochondriotropic agents conjugated with NSAIDs through metal ions against breast cancer cells

Two copper(I) polymorphs of formula [Cu(SALH)(TPP)3] (1a and 1b) were prepared by the conjugation of the Non-Steroidal Anti-Inflammatory Drug (NSAID) salicylic acid (SALH2) with the mitochondriotropic agent triphenylphosphine (TPP) via metal ion. For comparison, the isomorph [Ag(SALH)(TPP)3] (2) was prepared. The conjugates 1a, 1b and 2 were characterized by melting point (m.p.), Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy, Ultraviolet-Visible (UV-Vis) spectroscopy and nuclear magnetic resonance (1H NMR). The crystal structures of 1a, 1b and 2 were confirmed by X-ray diffraction crystallography (XRD). The ex vivo binding affinity of 1-2 towards CT (calf thymus)-DNA was studied by UV, fluorescence, viscosity and DNA Thermal Denaturation studies. Their inhibitory activity against lipoxygenase (LOX) (an enzyme which is mainly located in the mitochondrion) was determined. The in vitro activity of 1-2 was evaluated against human breast cancer cell lines MCF-7 (hormone depended (HD)) and MDA-MB 281 (hormone independent (HI)) cells. Compounds 1-2 inhibit stronger than cisplatin the cancerous cells. The molecular mechanism of action of 1-2 was suspected by the MCF-7 cells morphology and confirmed by DNA fragmentation, Acridine Orange/Ethidium Bromide (AO/EB) Staining and mitochondrial membrane permeabilization tests.

Necrosis-Inducing High-Valent Oxo-Rhenium(V) Complexes with Potent Antitumor Activity: Synthesis, Aquation Chemistry, Cisplatin Cross-Resistance Profile, and Mechanism of Action

Chemotherapy with the cytotoxic platinum (Pt) drugs cisplatin, carboplatin, and oxaliplatin is the mainstay of anticancer therapy in the clinic. The antitumor activity of Pt drugs originates from their ability to induce apoptosis via covalent adduct formation with nuclear DNA. While the phenomenal clinical success is highly encouraging, resistance and adverse toxic side effects limit the wider applicability of Pt drugs. To circumvent these limitations, we embarked on an effort to explore the antitumor potential of a new class of oxo-rhenium(V) complexes of the type [(N∧N)(EG)Re(O)Cl] (where EG = ethylene glycolate and N∧N = bipyridine, Bpy (1); phenanthroline, Phen (2); 3,4,7,8-tetramethyl-phenanthroline, Me4Phen (3)). Investigation of speciation chemistry in aqueous media revealed the formation of [(N∧N)Re(O)(OH)3] as the biologically active species. Complex 3 was found to be the most potent among the three, with IC50 values ranging from 0.1 to 0.4 μM against a panel of cancer cells, which is 5-70-fold lower when compared with cisplatin. The higher potency of 3 is attributed to its higher lipophilicity, which enhanced cellular uptake. Importantly, complex 3 efficiently overcomes cisplatin resistance in ovarian, lung, and prostate cancer cells. In addition to reporting the aquation chemistry and identifying the active species in aqueous media, we performed in-depth in vitro mechanistic studies, which revealed that complex 3 preferentially accumulates in mitochondria, depletes mitochondrial membrane potential, and upregulates intracellular reactive oxygen species (ROS), leading to ER stress-mediated necrosis-mediated cancer cell death.

Unlocking the potential of platinum drugs: organelle-targeted small-molecule platinum complexes for improved anticancer performance

Platinum-based drugs have revolutionized cancer chemotherapy; however, their therapeutic efficacy has been limited by severe side effects and drug resistance. Recently, approaches that target specific organelles in cancer cells have emerged as attractive alternatives to overcome these challenges. Many studies have validated these strategies and highlighted that organelle-targeted platinum complexes demonstrate increased anticancer activity, the ability to overcome drug resistance, novel molecular mechanisms, or even lower toxicity. This review provides a brief summary of various organelle-targeting strategies that promote the accumulation of platinum complexes in certain intracellular areas, such as the nucleus, mitochondria, endoplasmic reticulum (ER), and lysosomes. Moreover, the mechanisms through which these strategies improve anticancer performance, overcome drug resistance, and alter the action mode of conventional platinum drugs are discussed. By providing an extensive account of platinum complexes targeting different organelles, this review aims to assist researchers in understanding the design principles, identifying potential targets, and fostering innovative ideas for the development of platinum complexes.

A novel mitochondria-targeting compound exerts therapeutic effects against melanoma by inducing mitochondria-mediated apoptosis and autophagy in vitro and in vivo

Melanoma is the most invasive skin cancer, with a high mortality rate. However, existing therapeutic drugs have side effects, low reactivity, and lead to drug resistance. As the power source in cells, mitochondria play an important role in the survival of cancer cells and are an important target for tumor therapy. This study aimed to develop a new anti-melanoma compound that targets mitochondria, evaluate its effect on the proliferation and metastasis of melanoma cells, and explore its mechanism of action. The novel mitochondria-targeting compound, SCZ0148, was synthesized by modifying the structure of cyanine. Then, A375 and B16 cells were incubated with different concentrations of SCZ0148, and different doses of SCZ0148 were administered to A375 and B16 xenograft zebrafish. The results showed that SCZ0148 targeted mitochondria, had dose- and time-dependent effects on the proliferation of melanoma cell lines, and had no obvious side effects on normal cells. In addition, SCZ0148 induced melanoma cell apoptosis through the reactive oxygen species-mediated mitochondrial pathway of apoptosis and promoted autophagy. SCZ0148 significantly inhibited the migration of melanoma cells via a matrix metalloprotein 9-mediated pathway. Similarly, SCZ0148 inhibited melanoma cell proliferation in a concentration-dependent manner in vivo. In summary, SCZ0148 may be a novel anti-melanoma compound that targets mitochondria.

Structural changes in DNA by binding mitochondrion-targeted monofunctional platinum(II) complexes using molecular dynamics simulation study

Triphenylphosphonium (Ph3P+, TPP) is a highly effective mitochondrial targeting group, an example of using which on mitochondrion-targeted monofunctional platinum(II) agent as anticancer drug was OPT, with the -CH2Ph3P+ group at ortho position of the pyriplatin pyridine ring. To study how carrier ligands might affect the efficacy of OPT, we constructed two platinum(II) agents with bulky bidentate ligands based on OPT. DNA structural changes caused by these three platinum(II) agents using molecular dynamics simulations were analysed. Data regarding DNA conformational changes including helical parameter, base stacking, average structure, and principal component analyses has been obtained. We found that TPP-based monofunctional platinum(II) complexes with bulky carrier ligands may induce more significant DNA conformational changes. These results are beneficial for developing highly efficient mitochondrion-targeted platinum anticancer drugs with carrier ligands of different steric hindrance.

The Power of Kinetic Inertness in Improving Platinum Anticancer Therapy by Circumventing Resistance and Ameliorating Nephrotoxicity

Even in the modern era of precision medicine and immunotherapy, chemotherapy with platinum (Pt) drugs remains among the most commonly prescribed medications against a variety of cancers. Unfortunately, the broad applicability of these blockbuster Pt drugs is severely limited by intrinsic and/or acquired resistance, and high systemic toxicity. Considering the strong interconnection between kinetic lability and undesired shortcomings of clinical Pt drugs, we rationally designed kinetically inert organometallic Pt based anticancer agents with a novel mechanism of action. Using a combination of in vitro and in vivo assays, we demonstrated that the development of a remarkably efficacious but kinetically inert Pt anticancer agent is feasible. Along with exerting promising antitumor efficacy in Pt-sensitive as well as Pt-resistant tumors in vivo, our best candidate has the ability to mitigate the nephrotoxicity issue associated with cisplatin. In addition to demonstrating, for the first time, the power of kinetic inertness in improving the therapeutic benefits of Pt based anticancer therapy, we describe the detailed mechanism of action of our best kinetically inert antitumor agent. This study will certainly pave the way for designing the next generation of anticancer drugs for effective treatment of various cancers.

Enhanced Photodynamic Therapy by Improved Light Energy Capture Efficiency of Porphyrin Photosensitizers

OPINION STATEMENT

Photodynamic therapy (PDT) has garnered increasing attention in cancer treatment because of its advantages such as minimal invasiveness and selective destruction. With the development of PDT, impressive progress has been made in the preparation of photosensitizers, particularly porphyrin photosensitizers. However, the limited tissue penetration of the activating light wavelengths and relatively low light energy capture efficiency of porphyrin photosensitizers are two major disadvantages in conventional photosensitizers. Therefore, tissue penetration needs to be enhanced and the light energy capture efficiency of porphyrin photosensitizers improved through structural modifications. The indirect excitation of porphyrin photosensitizers using fluorescent donors (fluorescence resonance energy transfer) has been successfully used to address these issues. In this review, the enhancement of the light energy capture efficiency of porphyrins is discussed.

Subcellular visualization: Organelle-specific targeted drug delivery and discovery

Organelles perform critical biological functions due to their distinct molecular composition and internal environment. Disorders in organelles or their interacting networks have been linked to the incidence of numerous diseases, and the research of pharmacological actions at the organelle level has sparked pharmacists' interest. Currently, cell imaging has evolved into a critical tool for drug delivery, drug discovery, and pharmacological research. The introduction of advanced imaging techniques in recent years has provided researchers with richer biological information for viewing and studying the ultrastructure of organelles, protein interactions, and gene transcription activities, leading to the design and delivery of precision-targeted drugs. Therefore, this reviews the research on organelles-targeted drugs based upon imaging technologies and development of fluorescent molecules for medicinal purposes. We also give a thorough analysis of a number of subcellular-level elements of drug development, including subcellular research instruments and methods, organelle biological event investigation, subcellular target and drug identification, and design of subcellular delivery systems. This review will make it possible to promote drug research from the individual/cellular level to the subcellular level, as well as give a new focus based on newly found organelle activities.

Triarylphosphine-Coordinated Bipyridyl Ru(II) Complexes Induce Mitochondrial Dysfunction

While cancer cells rely heavily upon glycolysis to meet their energetic needs, reducing the importance of mitochondrial oxidative respiration processes, more recent studies have shown that their mitochondria still play an active role in the bioenergetics of metastases. This feature, in combination with the regulatory role of mitochondria in cell death, has made this organelle an attractive anticancer target. Here, we report the synthesis and biological characterization of triarylphosphine-containing bipyridyl ruthenium (Ru(II)) compounds and found distinct differences as a function of the substituents on the bipyridine and phosphine ligands. 4,4'-Dimethylbipyridyl-substituted compound 3 exhibited especially high depolarizing capabilities, and this depolarization was selective for the mitochondrial membrane and occurred within minutes of treatment in cancer cells. The Ru(II) complex 3 exhibited an 8-fold increase in depolarized mitochondrial membranes, as determined by flow cytometry, which compares favorably to the 2-fold increase observed by carbonyl cyanide chlorophenylhydrazone (CCCP), a proton ionophore that shuttles protons across membranes, depositing them into the mitochondrial matrix. Fluorination of the triphenylphosphine ligand provided a scaffold that maintained potency against a range of cancer cells but avoided inducing toxicity in zebrafish embryos at higher concentrations, displaying the potential of these Ru(II) compounds for anticancer applications. This study provides essential information regarding the role of ancillary ligands for the anticancer activity of Ru(II) coordination compounds that induce mitochondrial dysfunction.

Manganese(ii) complexes stimulate antitumor immunity via aggravating DNA damage and activating the cGAS-STING pathway

Activating the cyclic GMP-AMP synthase-stimulator of the interferon gene (cGAS-STING) pathway is a promising immunotherapeutic strategy for cancer treatment. Manganese(ii) complexes MnPC and MnPVA (P = 1,10-phenanthroline, C = chlorine, and VA = valproic acid) were found to activate the cGAS-STING pathway. The complexes not only damaged DNA, but also inhibited histone deacetylases (HDACs) and poly adenosine diphosphate-ribose polymerase (PARP) to impede the repair of DNA damage, thereby promoting the leakage of DNA fragments into cytoplasm. The DNA fragments activated the cGAS-STING pathway, which initiated an innate immune response and a two-way communication between tumor cells and neighboring immune cells. The activated cGAS-STING further increased the production of type I interferons and secretion of pro-inflammatory cytokines (TNF-α and IL-6), boosting the tumor infiltration of dendritic cells and macrophages, as well as stimulating cytotoxic T cells to kill cancer cells in vitro and in vivo. Owing to the enhanced DNA-damaging ability, MnPC and MnPVA showed more potent immunocompetence and antitumor activity than Mn2+ ions, thus demonstrating great potential as chemoimmunotherapeutic agents for cancer treatment.

Elucidating the Multimodal Anticancer Mechanism of an Organometallic Terpyridine Platinum(II) N-Heterocyclic Carbene Complex against Triple-Negative Breast Cancer In Vitro and In Vivo

Treatment of triple-negative breast cancer (TNBC) has long been a medical challenge because of the lack of effective therapeutic targets. Targeting lipid, carbohydrate, and nucleotide metabolism pathways has recently been proven as a promising option in view of three heterogeneous metabolic-pathway-based TNBC subtypes. Here, we present a multimodal anticancer platinum(II) complex, named Pt(II)caffeine, with a novel mode of action involving simultaneous mitochondrial damage, inhibition of lipid, carbohydrate, and nucleotide metabolic pathways, and promotion of autophagy. All these biological processes eventually result in a strong suppression of TNBC MDA-MB-231 cell proliferation both in vitro and in vivo. The results indicate that Pt(II)caffeine, influencing cellular metabolism at multiple levels, is a metallodrug with increased potential to overcome the metabolic heterogeneity of TNBC.

New Apoptosis Inducers Containing Anti-inflammatory Drugs and Pnictogen Derivatives: A New Strategy in the Development of Mitochondrial Targeting Chemotherapeutics

{[Ag₈(Mef)₈(μ₂-S,O-DMSO)₂(μ₂-O-DMSO)₂(O-DMSO)₈]·2(H₂O)} (1), [Ag(Mef)(tpP)₂] (2), [Ag(Mef)(tpAs)₃] (3), and {2 [Ag(Mef)(tpSb)₃] (DMSO)} (4) were obtained by the conjugation of mefenamic acid (MefH), a nonsteroidal anti-inflammatory drug (NSAID), with a mitochondriotropic derivative of pnictogen tpE (tp = triphenyl group; E = P, As, and Sb) through silver(I). Their hydrophilicity was adjusted by their dispersion into sodium lauryl sulfate (SLS), forming SLS@1-4. 1-4 and SLS@1-4 were characterized by their spectral data and X-ray crystallography. They inhibit the proliferation of human breast adenocarcinoma cells MCF-7 (hormone-dependent (HD)) and MDA-MB-231 (hormone-independent (HI)). X-ray fluorescence reveals the Ag cellular uptake. The in vitro and in vivo nongenotoxicity was confirmed with micronucleus (MN), Artemia salina, and Allium cepa assays. Their mechanism of action was studied by cell morphology, DNA fragmentation, acridine orange/ethidium bromide (AO/EB) staining, cell cycle arrest, mitochondrial membrane permeabilization tests, DNA binding affinity, and LOX inhibitory activity and was rationalized by regression analysis.

Development and validation of a mitochondrial energy metabolism-related risk model in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers and ranks third inmortality. Mitochondria are the energy manufacturers of cells. Disruption of mitochondrial energy metabolism pathways is strongly correlated with the onset and progression of HCC. Aberrant genes in mitochondrial energy metabolism pathways may represent a unique diagnostic and therapeutic targets that act as indicators for HCC.

METHODS

Gene expression data from 374 HCC patients and 50 controls were acquired from TCGA database. A total of 188 mitochondrial energy metabolism-related genes (MMRGs) were obtained from KEGG PATHWAY database. A total of 368 patients with survival data were randomly split into training and validation groups in a 7: 3 ratio. Prognosis-related MMRGs were selected by univariate Cox and LASSO analyses. Kaplan-Meier and ROC curves were employed to analyze the model precision, whereas the validation set was used for model verification. Furthermore, clinical examinations, immune infiltration analysis, GSVA, and immunotherapy analysis were conducted in the high- and low-risk groups. Finally, the risk model was combined with the clinical variables of HCC patients to perform univariate and multivariate Cox regression analyses to obtain independent risk indicators and draw a nomogram. Therefore, we evaluated the accuracy of the predictions using calibration curves.

RESULTS

A total of 6032 differentially expressed genes (DEGs) were detected in the HCC and control samples. After overlapping DEGs with 188 MMRGs, 42 mitochondrial energy metabolism-related DEGs (DEMMRGs) were identified. A 17 specific genes-based risk score model of HCC was created, which revealed effectiveness in each TCGA training and validation dataset. Moreover, patients categorized by risk scores exhibited distinct immune infiltration status, immunotherapy responsiveness, and functional properties. Finally, univariate and multivariate Cox regression analyses revealed that risk score and stage T were independent predictive variables. Based on the T stage and risk score, a nomogram for estimating the survival of HCC patients was created. The calibration curves demonstrated that the prediction model had a high level of accuracy.

CONCLUSIONS

Our study constructed a mitochondrial energy metabolism-related risk model, that may be utilized to anticipate HCC prognosis and represent the immunological microenvironment of HCC.

Recent Trends in the Development of Novel Metal-Based Antineoplastic Drugs

Since the accidental discovery of the anticancer properties of cisplatin more than half a century ago, significant efforts by the broad scientific community have been and are currently being invested into the search for metal complexes with antitumor activity. Coordination compounds of transition metals such as platinum (Pt), ruthenium (Ru) and gold (Au) have proven their effectiveness as diagnostic and/or antiproliferative agents. In recent years, experimental work on the potential applications of elements including lanthanum (La) and the post-transition metal gallium (Ga) in the field of oncology has been gaining traction. The authors of the present review article aim to help the reader "catch up" with some of the latest developments in the vast subject of coordination compounds in oncology. Herewith is offered a review of the published scientific literature on anticancer coordination compounds of Pt, Ru, Au, Ga and La that has been released over the past three years with the hope readers find the following article informative and helpful.

Mitochondria as a target of third row transition metal-based anticancer complexes

In pursuit of better treatment options for malignant tumors, metal-based complexes continue to show promise as attractive chemotherapeutics due to tunability, novel mechanisms, and potency exemplified by platinum agents. The metabolic character of tumors renders the mitochondria and other metabolism pathways fruitful targets for medicinal inorganic chemistry. Cumulative understanding of the role of mitochondria in tumorigenesis has ignited research in mitochondrial targeting metal-based complexes to overcome resistance and inhibit tumor growth with high potency and selectivity. Here, we discuss recent progress made in third row transition metal-based mitochondrial targeting agents with the goal of stimulating an active field of research toward new clinical anticancer agents and the elucidation of novel mechanisms of action.

Application Prospects of Triphenylphosphine-Based Mitochondria-Targeted Cancer Therapy

Cancer is one of the leading causes of death and the most important impediments to the efforts to increase life expectancy worldwide. Currently, chemotherapy is the main treatment for cancer, but it is often accompanied by side effects that affect normal tissues and organs. The search for new alternatives to chemotherapy has been a hot research topic in the field of antineoplastic medicine. Drugs targeting diseased tissues or cells can significantly improve the efficacy of drugs. Therefore, organelle-targeted antitumor drugs are being explored, such as mitochondria-targeted antitumor drugs. Mitochondria is the central site of cellular energy production and plays an important role in cell survival and death. Moreover, a large number of studies have shown a close association between mitochondrial metabolism and tumorigenesis and progression, making mitochondria a promising new target for cancer therapy. Combining mitochondrial targeting agents with drug molecules is an effective way of mitochondrial targeting. In addition, hyperpolarized tumor cell membranes and mitochondrial membrane potentially allow selective accumulation of mitochondria-targeted drugs. This enhances the direct killing of tumor cells by drug molecules while minimizing the potential toxicity to normal cells. In this review, we discuss the common pro-mitochondrial agents, the advantages of triphenylphosphine (TPP) in mitochondrial-targeted cancer therapy and systematically summarize various TPP-based mitochondria-targeting anticancer drugs.

Pd-Based Hybrid Nanoparticles As Multimodal Theranostic Nanomedicine

A nanodelivery system based on palladium nanoparticles (PdNP) and cisplatin (CisPt) was developed by physisorption of the drug onto the PdNP synthesized via a green redox process, using d-glucose and polyvinylpyrrolidone (PVP) as reducing and stabilizing/capping agents, respectively. UV-vis analysis and H₂-evolution measurements were carried out to prove the nanoparticles' capability to act as bimodal theranostic nanomedicine, i.e., having both plasmonic and photocatalytic properties. XPS, XRD, and TEM allowed light to be shed on the chemical composition and morphology of the PdNP. The analysis of the UV-visible spectra evidenced plasmonic peak changes for the hybrid nanoparticle-drug assembly (Pd@CisPt), which pointed to a significant interaction of CisPt with the NP surface. The drug loading was quantitatively estimated by ICP-OES measurements, while DLS and AFM confirmed the strong association of the drug with the nanoparticle surface. The test of SOD-like activity in a cell-free environment proved the maintenance of the antioxidant capability of PdNP also in the Pd@CisPt systems. Finally, Pd@CisPt tested in prostate cancer cells (PC-3 line) unveiled the antitumoral action of the developed nanomedicine, related to reactive oxygen species (ROS) generation, with a condition of protein misfolding/unfolding and DNA damage, as evidenced by cytotoxicity and MitoSOX assays, as well as Raman microspectroscopy, respectively. Cell imaging by confocal microscopy evidenced cellular uptake of the nanoparticles, as well as dynamic processes of copper ion accumulation at the level of subcellular compartments. Finally, cell migration studies upon treatment with Pd@CisPt evidenced a tunable response between the inhibitory effect of CisPt and the enhanced rate of cell migration for the metal NP alone, which pointed out the promising potential of the developed theranostic nanomedicine in tissue regeneration.

Potent Ruthenium-Ferrocene Bimetallic Antitumor Antiangiogenic Agent That Circumvents Platinum Resistance: From Synthesis and Mechanistic Studies to In Vivo Evaluation in Zebrafish

Emergence of resistance in cancer cells and dose-limiting side effects severely limit the widespread use of platinum (Pt) anticancer drugs. Multi-action hybrid anticancer agents that are constructed by merging two or more pharmacophores offer the prospect of circumventing issues of Pt drugs. Herein, we report the design, synthesis, and in-depth biological evaluation of a ruthenium-ferrocene (Ru-Fc) bimetallic agent [(η6-p-cymene)Ru(1,1,1-trifluoro-4-oxo-4-ferrocenyl-but-2-en-2-olate)Cl] and its five analogues. Along with aquation/anation chemistry, we evaluated the in vitro antitumor potency, Pt cross-resistance profile, and in vivo antiangiogenic properties. A structure activity analysis was performed to understand the impact of Fc, CF3, and p-cymene groups on the anticancer potency of the Ru-Fc hybrid. Finally, in addition to assessing cellular uptake and intracellular distribution, we demonstrated that the Ru-Fc hybrid binds to nucleophilic biomolecules and produces reactive oxygen species, which causes mitochondrial dysfunction and induces ER stress, leading to poly(ADP-ribose) polymerase-mediated necroptotic cell death.

Amorphous Ultra-Small Fe-Based Nanocluster Engineered and ICG Loaded Organo-Mesoporous Silica for GSH Depletion and Photothermal-Chemodynamic Synergistic Therapy

Intracellular oxidative amplification can effectively destroy tumor cells. Additionally, Fe-mediated Fenton reaction often converts cytoplasm H2 O2 to generate extensive hypertoxic hydroxyl radical (• OH), leading to irreversible mitochondrion damage for tumor celleradication, which is widely famous as tumor chemodynamic therapy (CDT). Unfortunately, intracellular overexpressed glutathione (GSH) always efficiently scavenges • OH, resulting in the significantly reduced CDT effect. To overcome this shortcoming and improve the oxidative stress in cytoplasm, Fe3 O4 ultrasmall nanoparticle encapsulated and ICG loaded organo-mesoporous silica nanovehicles (omSN@Fe-ICG) are constructed to perform both photothermal and GSH depletion to enhance the Fenton-like CDT, by realizing intracellular oxidative stress amplification. After this nanoagents are internalized, the tetrasulfide bonds in the dendritic mesoporous framework can be decomposed with GSH to amplify the toxic ROS neration by selectively converting H2 O2 to hydroxyl radicals through the released Fe-based nanogranules. Furthermore, the NIR laser-induced hyperthermia can further improve the Fenton reaction rate that simultaneously destroyed the mitochondria. As a result, the GSH depletion and photothermal assisted CDT can remarkably improve the tumor eradication efficacy.