Advances in thiosemicarbazone metal complexes as anti-lung cancer agents

Co-targeting CDK 4/6 and C-MYC/STAT3/CCND1 axis and inhibition of tumorigenesis and epithelial-mesenchymal-transition in triple negative breast cancer by Pt(II) complexes bearing NH3 as trans-co-ligand

In search of potential anticancer agents, we synthesized SNO-donor salicylaldimine main ligand-based Pt(II) complexes bearing NH3 as co-ligand at trans-position (C1-C6). These complexes showed similarity in structure with transplatin as the two N donor atoms of the main ligand and NH3 co-ligand were coordinated to Pt in trans position to each other. Each complex with different substituents on the main ligand was characterized thoroughly by detailed spectroscopic and spectrophotometric methods. Four of these complexes were studied in solid state by single crystal X-ray analysis. The stability of reference complex C1 was measured in solution state in DMSO‑d6 or its mixture with D2O using 1H NMR methods. These complexes were further investigated for their anticancer activity in triple-negative-breast (TNBC) cells including MDA-MB-231, MDA-MB-468 and MDA-MB-436 cells. All these complexes showed satisfactory cytotoxic effect as revealed by the MTT results. Importantly, the highly active complex C4 anticancer effect was compared to the standard chemotherapeutic agents including cisplatin, oxaliplatin and 5-fluorouracil (5-FU). Functionally, C4 suppressed invasion, spheroids formation ability and clonogenic potential of cancer cells. C4 showed synergistic anticancer effect when used in combination with palbociclib, JQ1 and paclitaxel in TNBC cells. Mechanistically, C4 inhibited cyclin-dependent kinase (CDK)4/6 pathway and targeted the expressions of MYC/STAT3/CCND1/CNNE1 axis. Furthermore, C4 suppressed the EMT signaling pathway that suggested a role of C4 in the inhibition of TNBC metastasis. Our findings may pave further in detailed mechanistic study on these complexes as potential chemotherapeutic agents in different types of human cancers.

Developing a Palladium(II) Agent to Overcome Multidrug Resistance and Metastasis of Liver Tumor by Targeted Multiacting on Tumor Cell, Inactivating Cancer-Associated Fibroblast and Activating Immune Response

To targeted overcome the multidrug resistance (MDR) and metastasis of liver tumors, we proposed to develop a palladium (Pd) agent based on a specific residue of human serum albumin (HSA) for multiacting on tumor cell and other components in the tumor microenvironment. To this end, a series of Pd(II) 2-acetylpyridine thiosemicarbazone compounds were optimized to obtain a Pd(II) compound (5b) with significant cytotoxicity against HepG2/ADM cells. Subsequently, we constructed a HSA-5b complex delivery system and revealed the structural mechanism of HSA delivering 5b. Importantly, 5b/HSA-5b effectively inhibited the growth and metastasis of multidrug resistant liver tumors, and HSA enhanced the targeting ability of 5b and reduced its side effects in vivo. Furthermore, we confirmed the mechanisms of 5b/HSA-5b integrating to overcome MDR and metastasis of liver tumors: multiacting on cancer cell, activating immune response, and inactivating cancer-associated fibroblasts.

Binding Mechanisms and Therapeutic Activity of Heterocyclic Substituted Arylazothioformamide Ligands and Their Cu(I) Coordination Complexes

Finding new sources of biologically active compounds for anticancer or antimicrobial therapies remains an active area of research. Azothioformamides (ATFs) with a 1,3 N=N-C=S heterodiene backbone are a new class of biologically active compounds that chelate metals (e.g., Cu) forming stable ATF metal coordination complexes. In this study, ATF ligands were prepared with pyrrolidine, piperidine, N-methylpiperazine, and morpholine substituents on the formamide as to add more heterocyclic drug-like character for biological studies. Formamide derivatives were then complexed with various Cu(I) salts to form coordination complexes. Cu(I) salts were selected as to create potential bioactive compounds with less toxicity. Binding association constants of each Cu(I) salt to ATF ligands were extrapolated from UV-vis titration studies and were corroborated with DFT calculations using a hybrid functional B3LYP method. It was observed that the smaller pyrrolidine functionalized ATFs bound to the Cu(I) salts had stronger binding than any of the larger six-membered-ring heterocycles with association values in the 104 - 105 M-1 range. The ATF-Cu(I) salt coordination complexes were then evaluated for antimicrobial activity against two bacteria (Staphylococcus aureus, Escherichia coli), one yeast (Candida albicans), four human cancer lines (A-549, K-562, HT-1080, MDA-MB-231), and two normal human lines (MRC-5, HFF). The ATF ligands themselves were inactive against all microbes and most human lines except K-562 cells, which were sensitive to three of the four ligands (IC50's = 7.0-25.5 μM). Most ATF-Cu(I) complexes showed low to medium micromolar activity against Candida albicans (IC50's 2.6-24.8 μM) and Staphylococcus aureus (IC50's = 3.4-37.7 μM), with increasing activity corresponding to complexes with higher binding association constants. The antiproliferative properties of ATF-Cu(I) metal salt complexes against mammalian cells were mixed, with low to medium micromolar activity across all cell lines. Notably, several ATF-Cu(I) salt coordination complexes showed submicromolar activity against the HT-1080 fibrosarcoma line (0.52-0.69 μM). The results demonstrate promising activity of ATF-Cu(I) complexes, particularly with pyrrolidine as the formamide component. These studies suggest that the stronger binding association values correlate to higher levels of biological activity.

Thiazole Functionalization of Thiosemicarbazone for Cu(II) Complexation: Moving toward Highly Efficient Anticancer Drugs with Promising Oral Bioavailability

In this work, we report the synthesis of a new thiosemicarbazone-based drug of N'-(di(pyridin-2-yl)methylene)-4-(thiazol-2-yl)piperazine-1-carbothiohydrazide (HL) featuring a thiazole spectator for efficient coordination with Cu(II) to give [CuCl(L)]2 (1) and [Cu(NO3)(L)]2 (2). Both 1 and 2 exhibit dimeric structures ascribed to the presence of di-2-pyridylketone moieties that demonstrate dual functions of chelation and intermolecular bridging. HL, 1, and 2 are highly toxic against hepatocellular carcinoma cell lines Hep-G2, PLC/PRF/5, and HuH-7 with half maximal inhibitory concentration (IC50) values as low as 3.26 nmol/mL (HL), 2.18 nmol/mL (1), and 2.54 × 10-5 nmol/mL (2) for PLC/PRF/5. While the free ligand HL may elicit its anticancer effect via the sequestration of bio-relevant metal ions (i.e., Fe3+ and Cu2+), 1 and 2 are also capable of generating cytotoxic reactive oxygen species (ROS) to inhibit cancer cell proliferation. Our preliminary pharmacokinetic studies revealed that oral administration (per os, PO) of HL has a significantly longer half-life t1/2 of 21.61 ± 9.4 h, nearly doubled as compared with that of the intravenous (i.v.) administration of 11.88 ± 1.66 h, certifying HL as an effective chemotherapeutic drug via PO administration.

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.

Recent progress in thiocarbazone metal complexes for cancer therapy via mitochondrial signalling pathway

Mitochondria are the energy factories of cells and are important targets for the development of novel tumour treatment strategies owing to their involvement in processes such as apoptosis, oxidative stress, and metabolic programming. Thiosemicarbazone metal complexes target mitochondria and reduce mitochondrial membrane potential. The breakdown of mitochondrial membrane potential is a key event in the early stage of apoptosis, which releases cytochrome C and other pro-apoptotic factors, activates the intracellular apoptotic enzyme cascade, and eventually causes irreversible apoptosis of tumour cells. Thiosemicarbazone metal complexes targeting the mitochondria have recently emerged as potential antitumour agents; therefore, this review describes the structural diversity of thiosemicarbazone metal [Fe(III), Cu(II), Ni(II), Zn(II), Ga(III), Pb(II), Au(III), and Ir(III)] complexes and explores their anti-tumour mechanisms that target mitochondrial pathways.

Exploration of morpholine-thiophene hybrid thiosemicarbazones for the treatment of ureolytic bacterial infections via targeting urease enzyme: Synthesis, biochemical screening and computational analysis

An important component of the pathogenicity of potentially pathogenic bacteria in humans is the urease enzyme. In order to avoid the detrimental impact of ureolytic bacterial infections, the inhibition of urease enzyme appears to be an appealing approach. Therefore, in the current study, morpholine-thiophene hybrid thiosemicarbazone derivatives (5a-i) were designed, synthesized and characterized through FTIR, 1H NMR, 13C NMR spectroscopy and mass spectrometry. A range of substituents including electron-rich, electron-deficient and inductively electron-withdrawing groups on the thiophene ring was successfully tolerated. The synthesized derivatives were evaluated in vitro for their potential to inhibit urease enzyme using the indophenol method. The majority of compounds were noticeably more potent than the conventional inhibitor, thiourea. The lead inhibitor, 2-(1-(5-chlorothiophen-2-yl)ethylidene)-N-(2-morpholinoethyl)hydrazinecarbothioamide (5g) inhibited the urease in an uncompetitive manner with an IC50 value of 3.80 ± 1.9 µM. The findings of the docking studies demonstrated that compound 5g has a strong affinity for the urease active site. Significant docking scores and efficient binding free energies were displayed by the lead inhibitor. Finally, the ADME properties of lead inhibitor (5g) suggested the druglikeness behavior with zero violation.

Evaluation of anticancer activity of novel platinum(II) bis(thiosemicarbazone) complex against breast cancer

The study aims to synthesize a novel bis(thiosemicarbazone) derivative based on platinum (thioPt) and evaluate its anticancer properties against MFC-7 and MDA-MB-231 breast cancer cells. A new platinum complex was synthesised by reacting K2PtCl4 with 2,2'-(1,2-diphenylethane-1,2-diylidene)bis(hydrazine-1-carbothioamide) in ethanol in the presence of K2CO3. In the obtained complex, the platinum atom is coordinated by a conjugated system = N-NC-S-The structures of the new compound were characterised using NMR spectroscopy, HR MS, IR, and X-ray structural analysis. The obtained results of the cytotoxicity assay indicate that compound thioPt had potent anticancer activity (MCF-7: 61.03 ± 3.57 µM, MDA-MB-231: 60.05 ± 5.40 µM) with less toxicity against normal MCF-10A breast epithelial cells, even compared to the reference compound (cisplatin). In addition, subsequent experiments found that thioPt induces apoptosis through both an extrinsic (↑caspase 8 activity) and intrinsic (↓ΔΨm) pathway, which ultimately leads to an increase in active caspase 3/7 levels. The induction of autophagy and levels of proteins involved in this process (LC3A/B and Beclin-1) were examined in MCF-7 and MDA-MB-231 breast cancer cells exposed to tested compounds (thio, thioPt, cisPt) at a concentration of 50 µM for 24 h. Based on these results, it can be concluded that thio and thioPt do not significantly affect the autophagy process. This demonstrates their superiority over cisplatin, which can stimulate cancer cell survival through its effect on stimulation of autophagy.

Silver nanoparticle functionalized by glutamine and conjugated with thiosemicarbazide induces apoptosis in colon cancer cell line

The high mortality rate of colon cancer indicates the insufficient efficacy of current chemotherapy. Thus, the discussion on engineered metal nanoparticles in the treatment of the disease has been considered. In this study, silver nanoparticles were functionalized with glutamine and conjugated with thiosemiccarbazide. Then, anticancer mechanism of Ag@Gln-TSC NPs in a colon cancer cell line (SW480) was investigated. Characterizing Ag@Gln-TSC NPs by FT-IR, XRD, EDS-mapping, DLS, zeta potential, and SEM and TEM microscopy revealed that the Ag@Gln-TSC NPs were correctly synthesized, the particles were spherical, with surface charge of - 27.3 mV, high thermal stability and low agglomeration level. Using MTT assay we found that Ag@Gln-TSC NPs were significantly more toxic for colon cancer cells than normal fibroblast cells with IC50 of 88 and 186 µg/mL, respectively. Flow cytometry analysis showed that treating colon cancer cells with Ag@Gln-TSC NPs leads to a considerable increase in the frequency of apoptotic cells (85.9% of the cells) and increased cell cycle arrest at the S phase. Also, several apoptotic features, including hyperactivity of caspase-3 (5.15 folds), increased expression of CASP8 gene (3.8 folds), and apoptotic nuclear alterations were noticed in the nanoparticle treated cells. Furthermore, treating colon cancer cells with Ag@Gln-TSC NPs caused significant down-regulation of the HULC Lnc-RNA and PPFIA4 oncogene by 0.3 and 0.6 folds, respectively. Overall, this work showed that Ag@Gln-TSC NPs can effectively inhibit colon cancer cells through the activation of apoptotic pathways, a feature that can be considered more in studies in the field of colon cancer treatment.

Novel mono-, bi-, tri- and tetra-nuclear copper complexes that inhibit tumor growth through apoptosis and anti-angiogenesis

To develop the next-generation metal agents for efficiently inhibiting tumor growth, a series of novel mononuclear, binuclear and trinuclear copper (Cu) thiophene-2-formaldehyde thiosemicarbazone complexes and a tetranuclear Cu 1,2,4-triazole-derived complex have been synthesized and their structure-activity relationships have been studied. The trinucleated Cu complex showed the strongest inhibitory activity against T24 cells among all the Cu complexes. Its antitumor effect in vivo was superior to that of cisplatin, with reduced side effects. Further studies on the antitumor mechanism have showed that Cu complexes not only induced apoptosis of cancer cells but also inhibited tumor angiogenesis by inhibiting the migration and invasion of vascular endothelial cells, blocking the cell cycle in the G1 phase, and inducing autophagy.

Anticancer Properties of Ru and Os Half-Sandwich Complexes of N,S Bidentate Schiff Base Ligands Derived from Phenylthiocarbamide

The versatile coordinating nature of N,S bidentate ligands is of great importance in medicinal chemistry imparting stability and enhancing biological properties of the metal complexes. Phenylthiocarbamide-based N,S donor Schiff bases converted into RuII /OsII (cymene) complexes and characterized by spectroscopic techniques and elemental analysis. The hydrolytic stability of metal complexes to undergo metal-halide ligand exchange reaction was confirmed both by the DFT and NMR experimentation. The ONIOM (QM/MM) study confirmed the histone protein targeting nature of aqua/hydroxido complex 2 aH with an excellent binding energy of -103.19 kcal/mol. The antiproliferative activity against a panel of cancer cells A549, MCF-7, PC-3, and HepG2 revealed that ruthenium complexes 1 a-3 a were more cytotoxic than osmium complexes and their respective ligands 1-3 as well. Among these ruthenium cymene complex bearing sulfonamide moiety 2 a proved a strong cytotoxic agent and showed excellent correlation of cellular accumulation, lipophilicity, and drug-likeness to the anticancer activity. Moreover, the favorable physiochemical properties such as bioavailability and gastrointestinal absorption of ligand 2 also supported the development of Ru complex 2 a as an orally active anticancer metallodrug.

Inhibition of Topoisomerases by Metal Thiosemicarbazone Complexes

Topoisomerases, common targets for anti-cancer therapeutics, are crucial enzymes for DNA replication, transcription, and many other aspects of DNA metabolism. The potential anti-cancer effects of thiosemicarbazones (TSC) and metal-TSC complexes have been demonstrated to target several biological processes, including DNA metabolism. Human topoisomerases were discovered among the molecular targets for TSCs, and metal-chelated TSCs specifically displayed significant inhibition of topoisomerase II. The processes by which metal-TSCs or TSCs inhibit topoisomerases are still being studied. In this brief review, we summarize the TSCs and metal-TSCs that inhibit various types of human topoisomerases, and we note some of the key unanswered questions regarding this interesting class of diverse compounds.

Crystal Design, Antitumor Activity and Molecular Docking of Novel Palladium(II) and Gold(III) Complexes with a Thiosemicarbazone Ligand

The current research describes the synthesis and characterization of 2-acetylpyridine N(4)-cyclohexyl-thiosemicarbazone ligand (HL) and their two metal complexes, [Au(L)Cl][AuCl₂] (1) and [Pd(L)Cl]·DMF (2). The molecular structures of the compounds were determined by physicochemical and spectroscopic methods. Single crystal X-ray diffraction was employed in the structural elucidation of the new complexes. The complexes showed a square planar geometry to the metal center Au(III) and Pd(II), coordinated with a thiosemicarbazone molecule by the NNS-donor system and a chloride ion. Complex (1) also shows the [AuCl₂]^- counter-ion in the asymmetric unit, and complex (2) has one DMF solvent molecule. These molecules play a key role in the formation of supramolecular structures due to different interactions. Noncovalent interactions were investigated through the 3D Hirshfeld surface by the d_norm function and the 2D fingerprint plots. The biological activity of the compounds was evaluated in vitro against the human glioma U251 cells. The cytotoxicity results revealed great antitumor activity in complex (1) compared with complex (2) and the free ligand. Molecular docking simulations were used to predict interactions and properties with selected proteins and DNA of the synthesized compounds.

The Role of NQO1 in Ovarian Cancer

Ovarian cancer is one of the most dangerous gynecologic malignancies showing a high fatality rate because of late diagnosis and relapse occurrence due to chemoresistance onset. Several researchers reported that oxidative stress plays a key role in ovarian cancer occurrence, growth and development. The NAD(P)H:quinone oxidoreductase 1 (NQO1) is an antioxidant enzyme that, using NADH or NADPH as substrates to reduce quinones to hydroquinones, avoids the formation of the highly reactive semiquinones, then protecting cells against oxidative stress. In this review, we report evidence from the literature describing the effect of NQO1 on ovarian cancer onset and progression.

Modulation of Transcription Profile Induced by Antiproliferative Thiosemicarbazone Metal Complexes in U937 Cancer Cells

Since the discovery of cisplatin, the search for metal-based compounds with therapeutic potential has been a challenge for the scientific community. In this landscape, thiosemicarbazones and their metal derivatives represent a good starting point for the development of anticancer agents with high selectivity and low toxicity. Here, we focused on the action mechanism of three metal thiosemicarbazones [Ni(tcitr)₂], [Pt(tcitr)₂], and [Cu(tcitr)₂], derived from citronellal. The complexes were already synthesized, characterized, and screened for their antiproliferative activity against different cancer cells and for genotoxic/mutagenic potential. In this work, we deepened the understanding of their molecular action mechanism using an in vitro model of a leukemia cell line (U937) and an approach of transcriptional expression profile analysis. U937 cells showed a significant sensitivity to the tested molecules. To better understand DNA damage induced by our complexes, the modulation of a panel of genes involved in the DNA damage response pathway was evaluated. We analyzed whether our compounds affected cell cycle progression to determine a possible correlation between proliferation inhibition and cell cycle arrest. Our results demonstrate that metal complexes target different cellular processes and could be promising candidates in the design of antiproliferative thiosemicarbazones, although their overall molecular mechanism is still to be understood.

Developing an Anticancer Platinum(II) Compound Based on the Uniqueness of Human Serum Albumin

To develop the next-generation Pt drug with remarkable activity and low toxicity to maximally inhibit tumor growth, we optimized a Pt(II) thiosemicarbazone compound (C4) with remarkable cytotoxicity to SK-N-MC cells and then constructed a new human serum albumin-C4 (HSA-C4) complex delivery system. The in vivo results showed that C4 and the HSA-C4 complex have remarkable therapeutic efficiency and almost no toxicity; they induced apoptosis and inhibited tumor angiogenesis. This system showed potential as a practical Pt drug. This study could pave the way for developing next-generation dual-targeted Pt drugs and achieving their targeting therapy for cancer.

Comparative evaluation of the structure and antitumor mechanism of mononuclear and trinucleated thiosemicarbazone Cu(II) complexes

The ratio of ligand to Cu(II) ions has an essential effect on the geometrical configuration and anti-tumour activity of metal-based complexes. In this work, we synthesised two Cu(II) thiosemicarbazone complexes, namely, [Cu(L)(Cl)] (C1) and [Cu₃(L)₂(Cl)₄] (C2), by controlling the ratio of Cu(II) ion to ligand, to evaluate their anti-tumour activity. The ability of C1 to catalyze hydrogen peroxide to produce reactive oxygen species (ROS) was significantly higher than that of Cu(II) ion. Moreover, the bridge of Cu(II) and two molecules generated a new complex (C2), which, in contrast to C1, enhanced the generation of Fenton-like-triggered ROS. Consequently, the produced ROS depleted reduced glutathione, caused oxidative cell stress and promoted apoptosis through mitochondrial apoptotic pathways. In addition, C2 exhibited better tumour suppression than C1 in a nude mouse tumour xenograft model.