Calcium release induced by 2-pyridinecarboxaldehyde thiosemicarbazone and its copper complex contributes to tumor cell death

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.

Desulfurization of thiosemicarbazones: the role of metal ions and biological implications

Thiosemicarbazones are biologically active substances whose structural formula is formed by an azomethine, an hydrazine, and a thioamide fragments, to generate a R2C=N-NR-C(=S)-NR2 backbone. These compounds often act as ligands to generate highly stable metal-organic complexes. In certain experimental conditions, however, thiosemicarbazones undergo reactions leading to the cleavage of the chain. Sometimes, the breakage involves desulfurization processes. The present work summarizes the different chemical factors that influence the desulfurization reactions of thiosemicarbazones, such as pH, the presence of oxidant reactants or the establishment of redox processes as those electrochemically induced, the effects of the solvent, the temperature, and the electromagnetic radiation. Many of these reactions require coordination of thiosemicarbazones to metal ions, even those present in the intracellular environment. The nature of the products generated in these reactions, their detection in vivo and in vitro, together with the relevance for the biological activity of these compounds, mainly as antineoplastic agents, is discussed.

Copper(II) complex enhanced chemodynamic therapy through GSH depletion and autophagy flow blockade

Three copper(II) complexes C1-C3 were synthesized and fully characterized as chemodynamic therapy (CDT) anticancer agents. C1-C3 showed greater cytotoxicity than their ligands toward SK-OV-3 and T24 cells. Particularly, C2 showed high cytotoxicity toward T24 cells and low cytotoxicity toward normal human HL-7702 and WI-38 cells. Mechanistic studies demonstrated that C2 oxidized GSH to GSSG and produced ˙OH, which induced mitochondrial dysfunction and ER stress, finally leading to apoptosis of T24 cells. In addition, C2 inhibited autophagy by blocking autophagy flow, thereby closing the self-protection pathway of oxidative stress to enhance CDT. Importantly, C2 significantly inhibited T24 tumor growth with 57.1% inhibition in a mouse xenograft model. C2 is a promising lead as a potential CDT anticancer agent.

Shared Hydrogen Atom Location and Chemical Composition in Picolinic Acid and Pyridoxal Hydrochloride Derivatives Determined by X-ray Crystallography

Three new single-crystal structures were isolated for picolinic acid (2), the trifluoroacetate salt of picolinic acid (1), and pyridoxal hydrochloride (3). These compounds displayed unconventional crystallographic features that must be considered when structural refinements are carried out. Thus, the generated Fourier differences map obtained with the diffraction data collected at 100 K was crucial to visualize electron densities, which were balanced by either one hydrogen atom or a hydrogen atom with an occupancy factor of 1/2 located between either two carboxylate moieties, two phenolic oxygen atoms, or two pyridinic nitrogen atoms. Moreover, NMR studies were conducted to analyze the bulk chemical composition of single crystals of 2-pyridinecarboxylic acid obtained from the gem-diol/hemiacetal forms and the polymerization products after the treatment of 2-pyridinecarboxaldehyde with TFA:H₂O (1) or a diluted Cu(NO₃)₂ solution (2). The quantitative yield of the pyridoxal hydrochloride crystalline material (3) obtained from a diluted CuCl₂ solution was exhaustively characterized by solid-state NMR methods. These methods allowed the resolution of the signals corresponding to the protons of the hydroxyl moiety of the intramolecular hemiacetal group and the phenolic hydrogen. Theoretical calculations using DFT methods were done to complement the atomic location of the hydrogen atoms obtained from the X-ray analysis.

A novel antitumor dithiocarbamate compound inhibits the EGFR/AKT signaling pathway and induces apoptosis in esophageal cancer cells

Dithiocarbamate has been reported to possess a potent antitumor efficacy against several types of cancer, such as ovarian cancer, breast cancer and hepatocellular carcinoma; however, only a few studies have investigated its inhibitory effect on esophageal cancer. Dipyridylhydrazone dithiocarbamate (DpdtC) is a novel dithiocarbamate derivative that was recently designed, synthesized and evaluated in our previous study. In the present study, the cell growth inhibition and apoptosis induced by DpdtC were measured using the CCK-8 and Annexin V-FITC/propidium iodide staining assays, respectively. Epidermal growth factor receptor (EGFR) signaling pathway and apoptosis related protein levels were examined by western blotting. In vivo effect of DpdtC was evaluated in nude mice bearing KYSE-450 ×enograft tumors. The aims of the present study were to further evaluate the antitumor effects of DpdtC on esophageal cancer cells (KYSE-150 and KYSE-450 cells), and to investigate its potential mechanism of action in vitro and in vivo. It was found that DpdtC significantly inhibited KYSE-150 and KYSE-450 cell proliferation by regulating the EGFR/AKT signaling pathway and inducing apoptosis. In addition, this effect was further identified in vivo; DpdtC inhibited the growth of the KYSE-450 esophageal cancer xenografts by regulating the EGFR/AKT signaling pathway. Furthermore, DpdtC did not affect the body weight in mice. Collectively, the present results suggested that DpdtC may be a promising antitumor drug candidate for the treatment of esophageal cancer.

Synthesis, molecular modelling, FT-IR, Raman and NMR characterization, molecular docking and ADMET study of new nickel(II) complex with an N4-tetradentate thiosemicarbazone

A new nickel(II) complex was synthesized by using S-propyl-thiosemicarbazide and 2-amino-3,5-dibromobenzaldehyde. The complex, obtained by the template effect of nickel ions, was structurally analysed by experimental and theoretical vibrational spectroscopy, NMR and density functional theory (DFT) calculations. By using DFT/B3LYP method with 6-311++G(d, p) basis set, the most stable molecular structure of the title molecule was calculated. The fundamental vibrational wavenumbers, IR and Raman intensities for the optimized structure of the molecule under investigation were determined and compared with the experimental vibrational spectra. The vibrational assignment was achieved using the calculated potential energy distributions of the vibrational modes. Moreover, the molecular electrostatic potential (MEP), the highest occupied molecular orbital (HOMO) and the lowest occupied molecular orbital (LUMO) energies were calculated, Molecular docking of the molecule was carried out against DNA in order to identify the potential inhibitory action of the title compound. The findings suggested that the aforementioned compound has a strong binding affinity to interact with DNA residues DT8, DC9, DG12, DG16, DA17, and DA18 through the intermolecular hydrogen bonds. Also the performed in silico ADMET analysis was the prediction of the synthesized molecule's pharmacokinetic and toxicity profile expressing good oral drug like actions and non-toxic nature. The complex has been shown to have the possibility to become a model molecule for drug development processes.Communicated by Ramaswamy H. Sarma.

Molecular mechanisms of apoptosis induction in K562 and KG1a leukemia cells by a water-soluble copper(II) thiosemicarbazone complex

Thiosemicarbazones (TSCs) and their metal complexes exhibit pronounced and selective cytotoxic potential against a broad span of cancers. Here, we assessed the anti-cancer activity of a water-soluble copper(II) complex of thiosemicarbazone (Cu-TSC) against two cancer cell lines of human leukemia. Our analysis revealed that Cu-TSC treatment results in a time and dose-dependent growth inhibition in K562 and KG1a cells while sparing normal human fibroblast (HFF2) cells. The IC₅₀ values for the Cu-TSC treatment were measured to be 21.7 ± 1.5 µM and 50.25 ± 2.5 µM for K562 and KG1a cells, respectively. Cell cycle analysis indicated that Cu-TSC induces the accumulation of cells in the sub-G1 fraction as well as the reversible arrest in G0/G1 and G2/M phases in K562 and KG1a cells, respectively. Furthermore, the occurrence of apoptosis as the prime mode of cell death was verified through apoptotic body formation, phosphatidylserine externalization, and caspase-3 activation. Additionally, the real-time quantitative PCR analysis revealed that Cu-TSC triggers apoptosis in both cell lines via the upregulation of caspases-8, -9, and the changing of Bax/Bcl2 ratio. Finally, flow cytometric analysis confirmed that Cu-TSC treatment causes the enhancement of reactive oxygen species formation in both K562 and KG1a cells. Altogether, these findings suggest that Cu-TSC is a promising inducer of apoptosis in leukemia cells and carries potential as an anti-cancer compound.

Thiosemicarbazone-metal complexes exhibiting cytotoxicity in colon cancer cell lines through oxidative stress

Colorectal cancer is the third most common type of cancer and has a high incidence in developed countries. At present, specific treatments are being required to allow individualized therapy depending on the molecular alteration on which the drug may act. The aim of this project is to evaluate whether HPTSC and HPTSC* thiosemicarbazones (HPTSC = pyridine-2-carbaldehyde thiosemicarbazone and HPTSC* = pyridine-2-carbaldehyde 4N-methylthiosemicarbazone), and their complexes with different transition metal ions as Cu(II), Fe(III) and Co(III), have antitumor activity in colon cancer cells (HT-29 and SW-480), that have different oncogenic characteristics. Cytotoxicity was evaluated and the involvement of oxidative stress in its mechanism of action was analyzed by quantifying the superoxide dismutase activity, redox state by quantification of the thioredoxin levels and reduced/oxidized glutathione rate and biomolecules damage. The apoptotic effect was evaluated by measurements of the levels of caspase 9 and 3 and the index of histones. All the metal-thiosemicarbazones have antitumor activity mediated by oxidative stress. The HPTSC*-Cu was the compound that showed the best antitumor and apoptotic characteristics for the cell line SW480, that is KRAS gene mutated.

Endoplasmic reticulum stress: an arising target for metal-based anticancer agents

Metal anticancer agents are rapidly emerging as selective, potent therapeutics that exhibit anticancer activity by inducing endoplasmic reticulum stress.

New Water-Soluble Copper(II) Complexes with Morpholine-Thiosemicarbazone Hybrids: Insights into the Anticancer and Antibacterial Mode of Action

Six morpholine-(iso)thiosemicarbazone hybrids HL¹–HL⁶ and their Cu(II) complexes with good-to-moderate solubility and stability in water were synthesized and characterized. Cu(II) complexes [Cu(L^1–6)Cl] (1–6) formed weak dimeric associates in the solid state, which did not remain intact in solution as evidenced by ESI-MS. The lead proligands and Cu(II) complexes displayed higher antiproliferative activity in cancer cells than triapine. In addition, complexes 2–5 were found to specifically inhibit the growth of Gram-positive bacteria Staphylococcus aureus with MIC₅₀ values at 2–5 μg/mL. Insights into the processes controlling intracellular accumulation and mechanism of action were investigated for 2 and 5, including the role of ribonucleotide reductase (RNR) inhibition, endoplasmic reticulum stress induction, and regulation of other cancer signaling pathways. Their ability to moderately inhibit R2 RNR protein in the presence of dithiothreitol is likely related to Fe chelating properties of the proligands liberated upon reduction.

Growth Inhibition of a Novel Iron Chelator, DpdtC, against Hepatoma Carcinoma Cell Lines Partly Attributed to Ferritinophagy-Mediated Lysosomal ROS Generation

Some iron chelators display significant anticancer activity that may involve ferritin degradation either in proteasomes or in lysosomes, and the latter might involve ferritinophagy with a period. However, the correlation of ferritinophagy with anticancer activity of iron chelator was not fully determined. Revealing the underlying link therefore is required. Di-2-pyridylketone dithiocarbamate (DpdtC), a novel iron chelator, could mobilize iron from ferritin and displayed excellent antitumor against hepatoma carcinoma cell lines (IC_50s = 0.4 ± 0.2 for HepG2 and 3.5 ± 0.3 μM for Bel-7402, resp.); we speculated that the antiproliferative action of DpdtC might involve ferritinophagy. To this end, the alterations of ferritin, microtubule-associated protein light chain 3 (LC3-II), and nuclear receptor coactivator 4 (NCOA4) were investigated after exposure of DpdtC to the cells. The results revealed that DpdtC could cause increases of autophagic vacuoles and LC3-II. The data from cellular immunofluorescence and Western blotting showed a reciprocal relation between abundances of ferritin and LC3-II, but the trends of NCOA4 and LC3-II in abundance were in a similar manner, indicating that a ferritinophagy occurred. Further studies revealed that the ferritinophagy evoked an iron-driven intralysosomal oxidative reaction, resulting in LMP change and lipid peroxidation. Thus, a ferritinophagy-mediated lysosomal ROS generation playing a role in the antiproliferative action of DpdtC could be proposed, which will enrich our knowledge of iron chelator in cancer therapy.

The novel dithiocarbamate, DpdtC suppresses HER2-overexpressed cancer cells by up-regulating NDRG1 via inactivation of HER2-ERK 1/2 signaling

Dithiocarbamate has been tested for its effective anti-tumor activity, but the underlying mechanism remains unclear. We previously prepared a novel diththiocarbamate derivative, DpdtC with an ability of catalase inhibition. Here, we for the first time investigated the growth inhibition effects of DpdtC on HER2-amplified cancer cells and elucidated its mechanism of action. Results showed that DpdtC exerted the potent anti-tumor effects against HER2-overexpressed SK-OV-3 and SK-BR-3 cells, especially on SK-OV-3 cells with a higher NDRG1 level, which was also confirmed in the SK-OV-3 xenograft model. Interestingly, we observed that NDRG1 was up-regulated, while membrane expression of HER2 was regressed in SK-OV-3 cells upon DpdtC treatment. In agreement, silencing endogenous NDRG1 also increased the expression of HER2 in SK-OV-3 cells, while overexpressing NDRG1 decreased HER2 expression in SK-BR-3 cells. Furthermore, our results showed the formation of the EGFR/HER2 heterodimer was attenuated and phosphorylation of ERK1/2 was inhibited in SK-OV-3 cells when treated with DpdtC. Collectively, these observations demonstrated that NDRG1 plays an important role in mediating the inhibition effects of DpdtC in HER2-overexpressed cancer cells via selective targeting of the HER2-ERK1/2 pathway. Hence, our investigation suggests that up-regulation of NDRG1 by DpdtC is a promising therapeutic approach in HER2-overexpressed cancers.