Novel glycosylation zinc(II)-cryptolepine complexes perturb mitophagy pathways and trigger cancer cell apoptosis and autophagy in SK-OV-3/DDP cells

With the aim of shedding some light on the mechanism of action of zinc(II) complexes in antiproliferative processes and molecular signaling pathways, three novel glycosylated zinc(II)-cryptolepine complexes, i.e., [Zn(QA1)Cl₂] (Zn(QA1)), [Zn(QA2)Cl₂] (Zn(QA2)), and [Zn(QA3)Cl₂] (Zn(QA3)), were prepared by conjugating a glucose moiety with cryptolepine, followed by complexation of the resulting glycosylated cryptolepine compounds N-((1-(2-morpholinoethyl)-1H-1,2,3-triazol-4-yl)methyl)-benzofuro[3,2-b]quinolin-11-amine (QA1), 2-(4-((benzofuro[3,2-b]quinolin-11-ylamino)methyl)-1H-1,2,3-triazol-1-yl)ethan-1-ol (QA2), and (2S,3S,4R,5R,6S)-2-(4-((benzofuro[3,2-b]quinolin-11-ylamino)-methyl)-1H-1,2,3-triazol-1-yl)-6-(hydroxymethyl)tetrahydro-2H-pyran-3,4,5-triol (QA3) with zinc(II), and their anticancer activity was evaluated. In MTT assays, Zn(QA1)-Zn(QA3) were more active against cisplatin-resistant ovarian SK-OV-3/DDP cancer cells (SK-OV-3cis) than ZnCl₂ and the QA1-QA3 ligands, with IC₅₀ values of 1.81 ± 0.50, 2.92 ± 0.32, and 1.01 ± 0.11 μM, respectively. Complexation of glycosylated cryptolepine QA3 with zinc(II) increased the antiproliferative activity of the ligand, suggesting that Zn(QA3) could act as a chaperone to deliver the active ligand intracellularly, in contrast with other cryptolepine metal complexes previously reported. In vivo and in vitro investigations suggested that Zn(QA3) exhibited enhanced anticancer activity with treatment effects comparable to those of the clinical drug cisplatin. Furthermore, Zn(QA1)-Zn(QA3) triggered SK-OV-3cis cell apoptosis through mitophagy pathways in the order Zn(QA1) > Zn(QA1) > Zn(QA2). These results demonstrate the potential of glycosylated zinc(II)-cryptolepine complexes for the development of chemotherapy drugs against cisplatin-resistant SK-OV-3cis cells.

Evaluation of the antitumor activity of a series of the pincer-type metallocomplexes produced from isonicotinohydrazide derivative

In this work we report on the antitumor properties of a series of pincer-type metallocomplexes [Hg₂(HL-keto)Cl₄]_n (1), [Hg(HL-keto)I₂] (2) and [Mn(HL-zwitterion)Cl₂]∙MeOH (3∙MeOH), derived from N'-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL) and corresponding metal salts. The Hg(II) and Mn(II) salts are chelated by the keto (HL-keto) or zwitterionic (HL-zwitterion) form of HL, respectively. The cytotoxic effects of these compounds have been accessed against lung adenocarcinoma (A549) and hepatocellular carcinoma (HepG2 and Huh7) cell lines. Complexes 1 and 2 were found to be most efficient against the cell line Huh7 with IC₅₀ value of 2.56 and 9.90 μM, respectively, while they exhibit moderate activity towards cell lines A549 and HepG2, as evidenced from IC₅₀ values in the range 27.98-56.99 μM. Complex 3∙MeOH is less efficient towards all the three cell lines with relatively high IC₅₀ values. The mechanisms of the metallocomplexes killing the aforementioned cells were elucidated by flow cytometry, colony formation and polymerase chain reaction (PCR) analysis of apoptosis related expression of the genes. The results of the cytotoxic effects and antitumor activity on different cell lines are affected by the metal nature and the presence of the coordinated halide.

Water soluble ionic Co(II), Cu(II) and Zn(II) diimine-glycinate complexes targeted to tRNA: structural description, in vitro comparative binding, cleavage and cytotoxic studies towards chemoresistant prostate cancer cells

Four new water soluble Co(ii), Cu(ii) and Zn(ii) ionic metal complexes (1-4) [Cu(diimine)(H2O)2(glycinate)]+[glycinate]-, [Co(diimine)(H2O)4]+[glycinate]- and [Zn(diimine) (H2O)4]+[glycinate]-, where diimine = 2,2'-bipyridine (1-3) and 1,10-phenanthroline (4) were synthesized and thoroughly characterized by spectroscopic and single X-ray crystallographic studies. Complex 1 possesses a triclinic crystal system with a penta-coordinated geometry whereas complexes 2-4 crystallized in an isostructural monoclinic system having distorted octahedral geometry. Density functional theory (DFT) studies for complexes 1-4 were performed to correlate their geometrical parameters and to calculate the energy of frontier molecular orbitals. The corroborative results of spectroscopic and voltammetric studies with ct-DNA and tRNA revealed that the complexes bind noncovalently via an electrostatic mode of binding with specificity for tRNA as compared to ct-DNA. Gel electrophoresis experiments revealed that all the complexes unwind the plasmid pBR322 DNA at low micromolar concentrations (2-9 μM) following an oxidative mechanism for Cu(ii) and Co(ii) complexes (1, 2 and 4) whereas the Zn(ii) complex (3) mediates DNA cleavage by the hydrolytic pathway. The tRNA cleavage showed concentration and time dependent activity of the complexes to promote RNA hydrolysis. Furthermore, the BSA binding ability of complexes 1-4 was monitored, which revealed that the complexes could quench the intrinsic fluorescence in a static manner. Complexes 1-4 were found to be non-toxic towards normal prostate epithelial cells, PNT2, but were potent against chemoresistant metastatic prostate cancer cells, Du145, with GI50 values ranging from 12.75-37 μM. Complexes 1 and 2 also showed cytotoxic activity against cancer stem cells having GI50 values of 14.70 and 14.90 μM, respectively. Molecular docking studies were performed with DNA and tRNA which further validated the spectroscopic analysis demonstrating the higher binding affinity of the complexes towards tRNA.

Novel nickel(II), palladium(II), and platinum(II) complexes having a pyrrolyl-iminophosphine (PNN) pincer: Synthesis, crystal structures, and cytotoxic activity

A pyrrolyl-iminophosphine (PNNH) which would act as a potential terdentate ligand has been prepared by Schiff base reaction. Complexes [M(PNN)X] (M = Ni; X = Cl (1), Pd; X = Cl (2), Br (3), I (4), M = Pt; X = Cl (5)) were prepared. The title complexes were characterized by various spectroscopic (IR, ¹H, ¹³C, and ³¹P NMR) and elemental analyses. The molecular structures of 1, 2, and 5 have been established by single-crystal X-ray crystallography, demonstrating a distorted square planar geometry comprising two 5-membered metallacyclic rings. Complexes 1 and 2 were found to crystallize in the orthorhombic while complex 5 crystallizes in the monoclinic. Cytotoxicities of the complexes along with PNNH were evaluated against A549 (lung), SK-OV-3 (ovarian), SM-MEL-2 (skin), and HCT15 (colon) human cancer cell lines by sulforhodamine B assay. Notably, the palladium(II) complex (2) shows the highest activity. Apoptosis activity along with the caspase inhibitor Z-VAD (Z-Val-Ala-Asp-fluoromethyl ketone) assay of 2 and 5 against A549 and HCT15 cancer cell lines were investigated to learn a mechanistic pathway for the observed cytotoxicity, practically eliminating an apoptotic cell-death route. Complexes 2 and 5 were studied to DNA cleavage assay and molecular docking simulation. The DNA (pcDNA3.0) cleavage experiment evaluates complex 5 interacting with DNA, more effectively, in comparison to complex 2. Molecular docking simulation of 2 and 5 toward DNA and GRP78 (glucose-regulated protein 78) was performed to predict binding sites of ligand-receptors and a plausible mechanistic aspect of metallodrug-action.

Synthesis, characterization, and antitumor properties of Au(i)–thiourea complexes

The complex Au(i)(3c)2OTf induced the ROS elevation and mitochondria-mediated apoptosis in a synergistic manner.

Systematic analysis of synergistic proteome modulations in a drug combination of cisplatin and MLN4924

Chemotherapeutic treatment regimens often take advantage of synergistic effects of drug combinations. Anticipating that synergistic effects on the cell biological level likely manifest on the proteome level, the analysis of proteome modulations represents an appropriate strategy to study drug combinations on a molecular level. More specifically, the detection of single proteins exhibiting synergistic abundance changes could be helpful to shed light on key molecules, which contribute in mechanisms facilitating the synergistic interaction and therefore represent potential targets for specific therapeutic approaches. In the reported study we aimed to provide evidence for this assumption and investigated the drug combination of cisplatin and the neddylation inhibitor MLN4924 in HCT-116 cells via cell biological analyses and mass spectrometry-based quantitative proteomics. From 1789 proteins quantified with two unique peptides, activated RNA polymerase II transcriptional coactivator p15 (SUB1) was highlighted as the most synergistically regulated protein using a synergistic scoring approach. Western blotting and analyses of cellular processes associated with this protein (DNA damage, oxidative stress and apoptosis) revealed supporting evidence for the synergistic regulation. Whereas the distinct role of SUB1 in the investigated drug combination needs to be elucidated in future studies, the presented results demonstrated the benefit and feasibility of synergistic scoring of proteome alterations to highlight proteins that likely contribute to the underlying molecular mechanisms of synergistic effects. Data are available via ProteomeXchange with identifier PXD009185.

A new C,N-cyclometalated osmium(ii) arene anticancer scaffold with a handle for functionalization and antioxidative properties

A series of six osmium(ii) complexes of the type [(η6-p-cymene)Os(C^N)X] (X = chlorido or acetato) containing benzimidazole C^N ligands with an ester group as a handle for further functionalization have been synthesized. They exhibit IC50 values in the low micromolar range in a panel of cisplatin (CDDP)-resistant cancer cells (approximately 10× more cytotoxic than CDDP in MCF-7), decrease the levels of intracellular ROS and reduce the NAD+ coenzyme, and inhibit tubulin polymerization. This discovery could open the door to a new large family of osmium(ii)-based bioconjugates with diverse modes of action.

Stimuli-Responsive Therapeutic Metallodrugs

The success of platinum-based anticancer agents has motivated the exploration of novel metal-based drugs for several decades, whereas problems such as drug-resistance and systemic toxicity hampered their clinical applications and efficacy. Stimuli-responsiveness of some metal complexes offers a good opportunity for designing site-specific prodrugs to maximize the therapeutic efficacy and minimize the side effect of metallodrugs. This review presents a comprehensive and up-to-date overview on the therapeutic stimuli-responsive metallodrugs that have appeared in the past two decades, where stimuli such as redox, pH, enzyme, light, temperature, and so forth were involved. The compounds are classified into three major categories based on the nature of stimuli, that is, endo-stimuli-responsive metallodrugs, exo-stimuli-responsive metallodrugs, and dual-stimuli-responsive metallodrugs. Representative examples of each type are discussed in terms of structure, response mechanism, and potential medical applications. In the end, future opportunities and challenges in this field are tentatively proposed. With diverse metal complexes being introduced, the foci of this review are pointed to platinum and ruthenium complexes.

In vitro and in silico study of the biological activity of manganese(III) inverse-[9-MC-3]-metallacrowns and manganese(II) complexes with the anti-inflammatory drugs diclofenac or indomethacin

In the present contribution, the biological properties of four manganese complexes with the non-steroidal anti-inflammatory drugs sodium diclofenac (Nadicl) or indomethacin (Hindo) in the presence or absence of salicylaldoxime (Η₂sao), i.e. [Μn₆(O)₂(dicl)₂(sao)₆(CH₃OH)₆] 1, [Μn₆(O)₂(indo)₂(sao)₆(H₂O)₄], 2, [Μn(dicl)₂(CH₃OH)₄], 3, and [Μn(indo)₂(CH₃OH)₄], 4 are presented. More specifically, the in vitro cytotoxic effects of the complexes were evaluated against three cancer cell lines (HeLa, MCF-7 and A549 cells) as well as their combinatory activity with the well-known chemotherapeutic drugs irinotecan, cisplatin, paclitaxel and 5-fluorouracil. The biological activity of the complexes was investigated in vitro by studying their affinity to calf-thymus DNA and their binding towards bovine or human serum albumin (HSA). Molecular docking simulations on the crystal structure of HSA and human estrogen receptor alpha (hERa) were employed in order to study in silico the ability of the studied complexes to bind to these proteins.