Exploitation of sulfated glycosaminoglycan status for precision medicine of Triplatin in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a subtype of breast cancer lacking targetable biomarkers. TNBC is known to be most aggressive, and when metastatic is often drug resistant and uncurable. Biomarkers predicting response to therapy improve treatment decisions and allow personalized approaches for TNBC patients. This study explores sulfated glycosaminoglycan (sGAG) levels as a predictor of TNBC response to platinum therapy. sGAG levels were quantified in three distinct TNBC tumor models including cell line-derived, patient-derived xenograft (PDX) tumors, and isogenic models deficient in sGAG biosynthesis. The in vivo antitumor efficacy of Triplatin, a sGAG-directed platinum agent, was compared in these models to the clinical platinum agent, carboplatin. We determined that >40% of TNBC PDX tissue microarray samples have high levels of sGAGs. The in vivo accumulation of Triplatin in tumors as well as antitumor efficacy of Triplatin positively correlated with sGAG levels on tumor cells, whereas carboplatin followed the opposite trend. In carboplatin-resistant tumor models expressing high levels of sGAGs, Triplatin decreased primary tumor growth, reduced lung metastases, and inhibited metastatic growth in lungs, liver, and ovaries. sGAG levels served as a predictor of Triplatin sensitivity in TNBC. Triplatin may be particularly beneficial in treating patients with chemotherapy-resistant tumors who have evidence of residual disease after standard neoadjuvant chemotherapy. More effective neoadjuvant and adjuvant treatment will likely improve clinical outcome of TNBC.

Investigation on Optical and Biological Properties of 2-(4-Dimethylaminophenyl)benzothiazole Based Cycloplatinated Complexes

The optical and biological properties of 2-(4-dimethylaminophenyl)benzothiazole cycloplatinated complexes featuring bioactive ligands ([{Pt(Me2 N-pbt)(C6 F5 )}L] [L=Me2 N-pbtH 1, p-dpbH (4-(diphenylphosphino)benzoic acid) 2, o-dpbH (2-(diphenylphosphino)benzoic acid) 3), [Pt(Me2 N-pbt)(o-dpb)] 4, [{Pt(Me2 N-pbt)(C6 F5 )}2 (μ-PRn P)] [PR4 P=O(CH2 CH2 OC(O)C6 H4 PPh2 )2 5, PR12 P=O{(CH2 CH2 O)3 C(O)C6 H4 PPh2 }2 6] are presented. Complexes 1-6 display 1 ILCT and metal-perturbed 3 ILCT dual emissions. The ratio between both bands is excitation dependent, accomplishing warm-white emissions for 2, 5 and 6. The phosphorescent emission is lost in aerated solutions owing to photoinduced electron transfer to 3 O2 and the formation of 1 O2 , as confirmed in complexes 2 and 4. They also exhibit photoinduced phosphorescence enhancement in non-degassed DMSO due to local oxidation of DMSO by sensitized 1 O2 , which causes a local degassing. Me2 N-pbtH and the complexes specifically accumulate in the Golgi apparatus, although only 2, 3 and 6 were active against A549 and HeLa cancer cell lines, 6 being highly selective in respect to nontumoral cells. The potential photodynamic property of these complexes was demonstrated with complex 4.

Covalent and noncovalent interactions of coordination compounds with DNA: An overview

Deoxyribonucleic acid plays a central role in crucial cellular processes, and many drugs exert their effects through binding to DNA. Since the discovery of cisplatin and its derivatives considerable attention of researchers has been focused on the development of novel anticancer metal-based drugs. Transition metal complexes, due to their great diversity in size and structure, have a big potential to modify DNA through diverse types of interactions, making them the prominent class of compounds for DNA targeted therapy. In this review we describe various binding modes of metal complexes to duplex DNA based on covalent and noncovalent interactions or combination of both. Specific examples of each binding mode as well as possible cytotoxic effects of metal complexes in tumor cells are presented.

Cancer therapeutic strategies based on metal ions

As a necessary substance to maintain the body's normal life activities, metal ions are ubiquitous in organisms and play a major role in various complex physiological and biochemical processes, such as material transportation, energy conversion, information transmission, metabolic regulation, etc. Their abnormal distribution/accumulation in cells can interfere with these processes, causing irreversible physical damage to cells or activating biochemical reactions to induce cell death. Therefore, metal ions can be exploited against a wide spectrum of cancers with high efficiency and without drug resistance, which can effectively inhibit the growth of cancer cells by triggering biocatalysis, breaking the osmotic balance, affecting metabolism, interfering with signal transduction, damaging DNA, etc. This perspective systematically summarizes the latest research progress of metal ion-based anti-tumor therapy, and emphasizes the challenges and development directions of this type of therapeutic strategy, hoping to provide a general implication for future research.

Selected polyoxopalladates as promising and selective antitumor drug candidates

Polyoxo-noble-metalates (PONMs), a class of molecular noble metal-oxo nanoclusters that combine features of both polyoxometalates and noble metals, are a promising platform for the development of next-generation antitumor metallodrugs. This study aimed to evaluate the antitumor potential against human neuroblastoma cells (SH-SY5Y), as well as toxicity towards healthy human peripheral blood cells (HPBCs), of five polyoxopalladates(II): (Na₈[Pd₁₃As₈O₃₄(OH)₆]·42H₂O (Pd₁₃), Na₄[SrPd₁₂O₆(OH)₃(PhAsO₃)₆(OAc)₃]·2NaOAc·32H₂O (SrPd₁₂), Na₆[Pd₁₃(AsPh)₈O₃₂]·23H₂O (Pd₁₃L), Na₁₂[SnO₈Pd₁₂(PO₄)₈]·43H₂O (SnPd₁₂), and Na₁₂[PbO₈Pd₁₂(PO₄)₈]·38H₂O (PbPd₁₂)), as the largest subset of PONMs. A pure inorganic, Pd₁₃, was found as the most potent and selective antineuroblastoma agent with IC₅₀ values (µM) of 7.2 ± 2.2 and 4.4 ± 1.2 for 24 and 48 h treatment, respectively, even lower than cisplatin (28.4 ± 7.4 and 11.6 ± 0.8). The obtained IC₅₀ values (µM) for 24/48 h treatment with SrPd₁₂ and Pd₁₃L were 75.8 ± 6.7/76.7 ± 22.9 and 63.8 ± 3.6/21.4 ± 10.8, respectively, whereas SnPd₁₂ and PbPd₁₂ did not remarkably affect the SH-SY5Y viability (IC₅₀ > > 100 µM). Pd₁₃ caused depolarisation of inner mitochondrial membrane prior to superoxide ion hyperproduction, followed by caspase activation, DNA fragmentation and cell cycle arrest, all hallmarks of apoptotic cell death, and accompanied by an increase in acidic vesicles content, suggestive of autophagy induction. Importantly, Pd₁₃ demonstrated the antitumor effect at concentrations not cytogenotoxic for normal HPBCs. On the contrary, SrPd₁₂ and Pd₁₃L at concentrations ≥ 1/3 IC₅₀ (24 h) decreased HPBC viability and increased % tail DNA up to 42% and 3.05 times, respectively, related to control. SnPd₁₂ and PbPd_12, previously confirmed promising antileukemic agents, did not exhibit cytogenotoxicity to HPBCs, and thus could be regarded as tumor cell specific and selective drug candidates.

Ru(II)-Naphthoquinone complexes with high selectivity for triple-negative breast cancer

Six new ruthenium(ii) complexes with lapachol (Lap) and lawsone (Law) with the general formula [Ru(L)(P-P)(bipy)]PF6, where L = Lap or Law, P-P = 1,2'-bis(diphenylphosphino)ethane (dppe), 1,4'-bis(diphenylphosphino)butane (dppb), 1,1'-bis(diphenylphosphino)ferrocene (dppf) and bipy = 2,2'-bipyridine, were synthesized, fully characterized by elemental analysis, molar conductivity, NMR, cyclic voltammetry, UV-vis, IR spectroscopies and three of them by X-ray crystallography. All six complexes were active against breast (MCF-7 and MDA-MB-231) and prostate (DU-145) cancer cell lines with lower IC50 values than cisplatin. Complex [Ru(Lap)(dppe)(bipy)]PF6 (1a) showed significant selectivity for MDA-MB-231, a model of triple-negative breast cancer (TNBC), as compared to the "normal-like" human breast epithelial cell line, MCF-10A. Complex (1a) inhibited TNBC colony formation and induced loss of cellular adhesion. Furthermore, the complex (1a) induced mitochondrial dysfunction and generation of ROS, as is involved in the apoptotic cell death pathway. Preferential cellular uptake of complex (1a) was observed in MDA-MB-231 cells compared to MCF-10A cells, consistent with the observed selectivity for tumorigenic vs. non-tumorigenic cells. Taken together, these results indicate that ruthenium complexes containing lapachol and lawsone as ligands are promising candidates as chemotherapeutic agents.

Metallodrug-protein interaction probed by synchrotron terahertz and neutron scattering spectroscopy

This experimental work applied coherent synchrotron-radiation terahertz spectroscopy and inelastic neutron scattering to address two processes directly associated with the mode of action of metal-based anticancer agents that can severely undermine chemotherapeutic treatment: drug binding to human serum albumin, occurring during intravenous drug transport, and intracellular coordination to thiol-containing biomolecules (such as metallothioneins) associated with acquired drug resistance. Cisplatin and two dinuclear platinum (Pt)- and palladium (Pd)-polyamine agents developed by this research group, which have yielded promising results toward some types of human cancers, were investigated. Complementary synchrotron-radiation-terahertz and inelastic neutron scattering data revealed protein metalation, through S- and N-donor ligands from cysteine, methionine, and histidine residues. A clear impact of the Pt and Pd agents was evidenced, drug binding to albumin and metallothionein having been responsible for significant changes in the overall protein conformation, as well as for an increased flexibility and possible aggregation.

Effect of Net Charge on DNA-Binding, Protein-Binding and Anticancer Properties of Copper(I) Phosphine-Diimine Complexes

The syntheses of [Cu(PPh3)2(L)]NO3 and [Cu(PPh3)2(L-SO3Na)]NO3 were achieved through the reaction of Cu(PPh3)2NO3 and equimolar amount of the ligands (L = 5,6-diphenyl-3-[2-pyridyl]-1,2,4-triazine; LSO3Na = 5,6-diphenyl-3-[2-pyridyl]-1,2,4-triazine-4,4′-disulfonic acid disodium salt). The complexes were characterized by NMR and IR spectroscopy and mass spectrometry. The compounds exhibit similar absorption and emission spectra, suggesting a similar electronic structure. Ct-DNA binding studies show the strong influence of the net charge as Cu-L (positively charged) is able to bind to ct-DNA while Cu-LSO3Na (negatively charged) is not. The net charge of the complexes affects the thermodynamic and kinetic binding parameters toward human serum albumin. HSA-binding of the complexes was further investigated by molecular docking, revealing different binding sites on the HSA protein as a function of the net charge. The different anticancer activities of the complexes towards ovcar-3 and hope-62 cancer cell lines are suggestive of a role for the overall charge of the complexes. Interaction with the DNA is not the major mechanism for this class of complexes. The overall net charge of the pharmacophore (anticancer agent) should be a key consideration in the design of anticancer metal complexes.

Maloplatin-B, a Cisplatin-Based BODIPY-Tagged Mito-Specific "Chemo-PDT" Agent Active in Red Light

Maloplatin-B, a cisplatin-based complex, namely [Pt(A-BOD)(NH₃)₂](NO₃) (Pt-A-BOD) with a pendant boron-dipyrromethene (BODIPY) moiety, where HA-BOD is a methyl malonyl chloride derived monostyryl BODIPY ligand, was designed and developed as near-IR light (600-720 nm) organelle-targeting photodynamic therapy agent. The complex [Pt(acac)(NH₃)₂](NO₃) (Pt-Ac) was used as a control. Pt-A-BOD displayed an absorption band at 616 nm (ε = 2.9 × 10⁴ M^-1 cm^-1) in 10% dimethyl sulfoxide/Dulbecco's Modified Eagle's Medium (DMSO/DMEM, pH 7.2). This complex displayed a broad emission band within 650-850 nm with a λ_em value of 720 nm in 10% DMSO-DMEM (pH 7.2) upon excitation (λ_ex) at 615 nm with a large Stokes shift. The fluorescence quantum yield (Φ_F) value for Pt-A-BOD is 0.032 and for the ligand HA-BOD is 0.24. The BODIPY complex and ligand showed the formation of singlet oxygen as the ROS (reactive oxygen species) on irradiation with near-IR red light of 660 nm, as evidenced from a 1,3-diphenylisobenzofuran (DPBF) assay. The complex displayed remarkable apoptotic NIR light-induced PDT activity with half-maximum inhibitory concentration values (IC₅₀) of 1.6-2.4 μM in A549 lung and HeLa cervical cancer cells, while it was less active in the dark. The cellular ROS generation by the complex in red light was ascertained by a DCFDA (2',7'-dichlorofluorescein diacetate) assay. Cellular imaging showed its localization primarily in the mitochondria of A549 cancer cells. The JC1 and Annexin-V FITC/PI assays carried out for A549 cancer cells treated with the BODIPY complex showed the alteration of mitochondrial membrane potential and apoptotic cell death on near-IR red light (600-720 nm) irradiation, respectively.

Antifungal promising agents of zinc(II) and copper(II) derivatives based on azole drug

A series of new metal complexes, [Zn(KTZ)₂(Ac)₂]·H₂O (1)_, [Zn(KTZ)₂Cl₂]·0.4CH₃OH (2), [Zn(KTZ)₂(H₂O)(NO₃)](NO₃) (3), [Cu(KTZ)₂(Ac)₂]·H₂O (4)_, [Cu(KTZ)₂Cl₂]·3.2H₂O (5), [Cu(KTZ)₂(H₂O)(NO₃)](NO₃)·H₂O (6), were synthesized by a reaction of ketoconazole (KTZ) with their respective zinc or copper salts under mild conditions. Similarly, six corresponding metal-CTZ (clotrimazole) complexes [Zn(CTZ)₂(Ac)₂]·4H₂O (7)_, [Zn(CTZ)₂Cl₂] (8), [Zn(CTZ)₂(H₂O)(NO₃)](NO₃)·4H₂O (9), [Cu(CTZ)₂(Ac)₂]·H₂O (10)_, [Cu(CTZ)₂Cl₂]·2H₂O (11), [Cu(CTZ)₂(H₂O)(NO₃)](NO₃)·2H₂O (12), were obtained. These metal complexes were characterized by elemental analyses, molar conductivity, ¹H and ¹³C{¹H} nuclear magnetic resonance, UV/Vis, and infrared spectroscopies. Further, the crystal structure for complexes 7 and 10 was determined by single-crystal X-ray diffraction. The antifungal activity of these metal complexes was evaluated against three fungal species of medical relevance: Candida albicans, Cryptococcus neoformans, and Sporothrix brasiliensis. Complexes 1 and 3 exhibited the greatest antifungal activity with a broad spectrum of action at low concentrations and high selectivity. Some morphological changes induced by these metal complexes in S. brasiliensis cells included yeast-hyphae conversion, an increase in cell size and cell wall damage. The strategy of coordination of clinic drugs (KTZ and CTZ) to zinc and copper was successful, since the corresponding metal complexes were more effective than the parent drug. Particularly, the promising antifungal activities displayed by Zn-KTZ complexes make them potential candidates for the development of an alternative drug to treat mycoses.

Antitumor substitution-inert polynuclear platinum complexes stabilize G-quadruplex DNA and suppress G-quadruplex-mediated gene expression

Anticancer substitution-inert polynuclear platinum(ii) complexes (SI-PPCs) effectively stabilize DNA G-quadruplexes (G4) and terminate DNA polymerization on templates containing G4-forming sequences.

Luminescent terpyridine appended geminal bisazide and bistriazoles: multinuclear Pt(II) complexes and AIPE-based DNA detection with the naked eye

We report square planar Pt(ii) complexes as luminescent biosensors for DNA detection in solution. The sensing is attributed to the aggregation induced bright red photoluminescence (AIPE) of the complexes in the presence of DNA that can be seen with the naked eye using only a 360 nm light source. Terpyridine appended luminescent geminal bistriazoles (L1-L4, from geminal bisazide A through azide-alkyne 'click' cycloaddition) with versatile chelating sites were explored for metal coordination and reaction with Pt(dmso)2Cl2 yielding tetranuclear and dinuclear complexes of Pt(ii) with different N∩N ligand environments. Thermally stable gem-bisazide and bistriazoles are hardly reported in the literature and this is the first report of terpyridine appended geminal bisazide and bistriazoles.

Integrated experimental/computational approaches to characterize the systems formed by vanadium with proteins and enzymes

An integrated instrumental/computational approach to characterize metallodrug–protein adducts at the molecular level is reviewed. A series of applications are described, focusing on potential vanadium drugs with a generalization to other metals.

Fluorinated Cycloplatinated(II) Complexes Bearing Bisphosphine Ligands as Potent Anticancer Agents

A family of cationic cycloplatinated(II) complexes [Pt(dfppy)(P^P)]Cl, dfppy = 2-(2,4-difluorophenyl)pyridine, incorporating bisphosphine ligands, P^P = bis(diphenylphosphino)methane (1, dppm), 1,2-bis(diphenylphosphino)ethane (2, dppe) and 1,2-bis(diphenylphosphino)benzene (3, dppbz), was prepared. The complexes were characterized by means of several analytical and spectroscopic methods. These complexes displayed acceptable stability in the biological environments which was confirmed by NMR, HR ESI-MS and UV-vis techniques. The antiproliferative properties of these complexes were evaluated by National Cancer Institute (NCI) at National Institutes of Health (NIH) against 60 different human tumor cell lines such as leukemia, melanoma, lung, colon, brain, ovary, breast, prostate and kidney. These complexes showed higher cytotoxicity than cisplatin against a wide variety of cancer cell lines such as K-562 (leukemia), HOP-92 (lung), HCT-116 (colon), OVCAR-8 (ovarian), PC-3 (prostate), MDA-MB-468 (breast), and melanoma cancer cell lines. Complex 3 as the most potent compound in this study furnished an excellent anti-proliferative activity compared to the cisplatin against Hela, SKOV3, and MCF-7 cancer cell lines. The main mode of the interaction of 1-3 with DNA was also determined using molecular docking studies.

Pharmacological Properties of Pt(II) and Pt(IV) Complexes with 2,2'-Dipyridylamine; the Comparative In Vitro Thereof

Pt-based drugs such as cisplatin are frontline drugs used for the treatment of different solid malignancies. However, they represent major problems, such as severe side effects and drug resistance. To find out the structure-activity relationship; in this study, Pt(II) and Pt(IV) complexes with similar ligands, namely tetrachloro(2,2'-dipyridylamine)platinum(IV) (1) and dichloro(2,2'-dipyridylamine)platinum(II) (2) were synthesized, tested for their in vitro activity over different tumor cell lines and compared with cisplatin. Despite nontoxicity against nonmalignant cells, both titled compounds depict considerable killing activity over HT-29 cells. So, this cell line is served for further investigation. Cell cycle test revealed that the mechanism of cell cycle arrest induced by complexes 1 and 2 over HT-29 cells was relatively similar and obviously different from cisplatin. Moreover, apoptosis analysis showed that late apoptosis/necrosis is the primary disease for the death of cell by three complexes. Comet assay and colony-forming test were also performed on HT-29 cells whose results were thoroughly discussed.

Synthesis of Platinum(II) Complexes with Some 1-Methylnitropyrazoles and In Vitro Research on Their Cytotoxic Activity

A series of eight novel platinum(II) complexes were synthesized by the reaction of the appropriate 1-methylnitropyrazole derivatives with K₂PtCl₄ and characterized by elemental analysis, ESI MS spectrometry, ¹H NMR, ¹⁹⁵Pt NMR, IR and far IR spectroscopy. Thermal isomerization of cis-dichloridobis(1-methyl-4-nitropyrazole)platinum(II) 1 to trans-dichloridobis(1-methyl-4-nitropyrazole)platinum(II) 2 has been presented, and the structure of the compound 2 has been confirmed by X-ray diffraction method. Cytotoxicity of the investigated compounds was examined in vitro on three human cancer cell lines (MCF-7 breast, ES-2 ovarian and A-549 lung adenocarcinomas) and their logP was measured using a shake-flask method. The trans complex 2 showed better antiproliferative activity than cisplatin for all the tested cancer cell lines. Additionally, trans-dichloridobis(1-methyl-5-nitropyrazole)platinum(II) 4 has featured a lower IC₅₀ value than reference cisplatin against MCF-7 cell line. To gain additional information that may facilitate the explanation of the mode of action of tested compounds cellular platinum uptake, stability in L-glutathione solution, influence on cell cycle progression of HL-60 cells and ability to apoptosis induction were determined for compounds 1 and 2.

Influence of Ligand and Nuclearity on the Cytotoxicity of Cyclometallated C^N^C Platinum(II) Complexes

A series of cyclometallated mono- and di-nuclear platinum(II) complexes and the parent organic ligand, 2,6-diphenylpyridine 1 (HC^N^CH), have been synthesized and characterized. This library of compounds includes [(C^N^C)PtII (L)] (L=dimethylsulfoxide (DMSO) 2 and triphenylphosphine (PPh3 ) 3) and [((C^N^C)PtII )2 (L')] (where L'=N-heterocycles (pyrazine (pyr) 4, 4,4'-bipyridine (4,4'-bipy) 5 or diphosphine (1,4-bis(diphenylphosphino)butane (dppb) 6). Their cytotoxicity was assessed against four cancerous cell lines and one normal cell line, with results highlighting significantly increased antiproliferative activity for the dinuclear complexes (4-6), when compared to the mononucleated species (2 and 3). Complex 6 is the most promising candidate, displaying very high selectivity towards cancerous cells, with selectivity index (SI) values >29.5 (A2780) and >11.2 (A2780cisR), and outperforming cisplatin by >4-fold and >18-fold, respectively.

Metallodrugs are unique: opportunities and challenges of discovery and development

Metals play vital roles in nutrients and medicines and provide chemical functionalities that are not accessible to purely organic compounds. At least 10 metals are essential for human life and about 46 other non-essential metals (including radionuclides) are also used in drug therapies and diagnostic agents. These include platinum drugs (in 50% of cancer chemotherapies), lithium (bipolar disorders), silver (antimicrobials), and bismuth (broad-spectrum antibiotics). While the quest for novel and better drugs is now as urgent as ever, drug discovery and development pipelines established for organic drugs and based on target identification and high-throughput screening of compound libraries are less effective when applied to metallodrugs. Metallodrugs are often prodrugs which undergo activation by ligand substitution or redox reactions, and are multi-targeting, all of which need to be considered when establishing structure-activity relationships. We focus on early-stage in vitro drug discovery, highlighting the challenges of evaluating anticancer, antimicrobial and antiviral metallo-pharmacophores in cultured cells, and identifying their targets. We highlight advances in the application of metal-specific techniques that can assist the preclinical development, including synchrotron X-ray spectro(micro)scopy, luminescence, and mass spectrometry-based methods, combined with proteomic and genomic (metallomic) approaches. A deeper understanding of the behavior of metals and metallodrugs in biological systems is not only key to the design of novel agents with unique mechanisms of action, but also to new understanding of clinically-established drugs.

Substitution-Inert Polynuclear Platinum Complexes Inhibit Reverse Transcription Preferentially in RNA Triplex-Forming Templates

RNA triplexes are significant tertiary structure motifs that are found in many functional RNAs. Hence, small molecules capable of recognition, binding, and stabilization of the triple-helical RNA structures are emerging as attractive potential molecular biology tools and therapeutic agents. Here, we utilize methods of molecular biology and biophysics to study the interactions of a series of antitumor substitution-inert polynuclear platinum complexes (SI-PPCs) with triple-helical RNA structures. We show that SI-PPCs recognize and stabilize RNA triplexes and inhibit reverse transcription preferentially in the RNA template prone to the triplex formation. These so far unexplored properties of SI-PPCs suggest that the targeting of triple-stranded regions in RNA might contribute to the biological effects of SI-PPCs.

Stronger Cytotoxicity for Cancer Cells Than for Fast Proliferating Human Stem Cells by Rationally Designed Dinuclear Complexes

Cytostatic metallo-drugs mostly bind to the nucleobases of DNA. A new family of dinuclear transition metal complexes was rationally designed to selectively target the phosphate diesters of the DNA backbone by covalent bonding. The synthesis and characterization of the first dinuclear Ni^II₂ complex of this family are presented, and its DNA binding and interference with DNA synthesis in polymerase chain reaction (PCR) are investigated and compared to those of the analogous Cu^II₂ complex. The Ni^II₂ complex also binds to DNA but forms fewer intermolecular DNA cross-links, while it interferes with DNA synthesis in PCR at lower concentrations than Cu^II₂. To simulate possible competing phosphate-based ligands in vivo, these effects have been studied for both complexes with 100-200-fold excesses of phosphate and ATP, which provided no disturbance. The cytotoxicity of both complexes has been studied for human cancer cells and human stem cells with similar rates of proliferation. Cu^II₂ shows the lowest IC₅₀ values and a remarkable preference for killing the cancer cells. Three different assays show that the Cu^II₂ complex induces apoptosis in cancer cells. These results are discussed to gain insight into the mechanisms of action and demonstrate the potential of this family of dinuclear complexes as anticancer drugs acting by a new binding target.

Molecular dynamics simulation of non-covalent interactions between polynuclear platinum(II) complexes and DNA

Several studies with substitution-inert polynuclear platinum(II) complexes (SI-PPC) have been carried out in recent years due to the form of DNA binding presented by these compounds. This form of bonding is achieved by molecular recognition through the formation of non-covalent structures, commonly called phosphate clamps and forks, which generate small extensions of the major and minor grooves. In this work, we use molecular dynamics simulations (MD) to study the formation of these cyclical structures between six different SI-PPCs and a double DNA dodecamer, here called 24_bp_DNA. The results showed the influence of the complex expressed on the number of phosphate clamps and forks formed. Based on the conformational characterization of the DNA fragment, we show that the studied SI-PPCs interact preferentially in the minor groove, causing groove spanning, except for two of them, Monoplatin and AH44. The phosphates of C-G pairs are the main sites for such non-covalent interactions. The Gibbs interaction energy of solvated species points out to AH78P, AH78H, and TriplatinNC as the most probable ones when coupled with DNA. As far as we know, this work is the very first one related to SI-PPCs which brings MD simulations and a complete analysis of the non-covalent interactions with a double DNA dodecamer.

ESI-MS Study of the Interaction of Potential Oxidovanadium(IV) Drugs and Amavadin with Model Proteins

In this study, the binding to lysozyme (Lyz) of four important VIV compounds with antidiabetic and/or anticancer activity, [VIVO(pic)2(H2O)], [VIVO(ma)2], [VIVO(dhp)2], and [VIVO(acac)2], where pic-, ma-, dhp-, and acac- are picolinate, maltolate, 1,2-dimethyl-3-hydroxy-4(1H)-pyridinonate, and acetylacetonate anions, and of the vanadium-containing natural product amavadin ([VIV(hidpa)2]2-, with hidpa3- N-hydroxyimino-2,2'-diisopropionate) was investigated by ElectroSpray Ionization-Mass Spectrometry (ESI-MS). Moreover, the interaction of [VIVO(pic)2(H2O)], chosen as a representative VIVO2+ complex, was examined with two additional proteins, myoglobin (Mb) and ubiquitin (Ub), to compare the data. The examined vanadium concentration was in the range 15-150 μM, i.e., very close to that found under physiological conditions. With pic-, dhp-, and hidpa3-, the formation of adducts n[VIVOL2]-Lyz or n[VIVL2]-Lyz is favored, while with ma- and acac- the species n[VIVOL]-Lyz are detected, with n dependent on the experimental VIV/protein ratio. The behavior of the systems with [VIVO(pic)2(H2O)] and Mb or Ub is very similar to that of Lyz. The results suggested that under physiological conditions, the moiety cis-VIVOL2 (L = pic-, dhp-) is bound by only one accessible side-chain protein residue that can be Asp, Glu, or His, while VIVOL+ (L = ma-, acac-) can interact with the two equatorial and axial sites. If the VIV complex is thermodynamically stable and does not have available coordination positions, such as amavadin, the protein cannot interact with it through the formation of coordination bonds and, in such cases, noncovalent interactions are predicted. The formation of the adducts is dependent on the thermodynamic stability and geometry in aqueous solution of the VIVO2+ complex and affects the transport, uptake, and mechanism of action of potential V drugs.

Development and In Vivo Application of a Water-Soluble Anticancer Copper Ionophore System Using a Temperature-Sensitive Liposome Formulation

Liposomes containing copper and the copper ionophore neocuproine were prepared and characterized for in vitro and in vivo anticancer activity. Thermosensitive PEGylated liposomes were prepared with different molar ratios of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and hydrogenated soybean phosphatidylcholine (HSPC) in the presence of copper(II) ions. Optimal, temperature dependent drug release was obtained at 70:30 DPPC to HSPC weight ratio. Neocuproine (applied at 0.2 mol to 1 mol phospholipid) was encapsulated through a pH gradient while using unbuffered solution at pH 4.5 inside the liposomes, and 100 mM HEPES buffer pH 7.8 outside the liposomes. Copper ions were present in excess, yielding 0.5 mM copper-(neocuproine)₂ complex and 0.5 mM free copper. Pre-heating to 45 °C increased the toxicity of the heat-sensitive liposomes in short-term in vitro experiments, whereas at 72 h all investigated liposomes exhibited similar in vitro toxicity to the copper(II)-neocuproine complex (1:1 ratio). Thermosensitive liposomes were found to be more effective in reducing tumor growth in BALB/c mice engrafted with C26 cancer cells, regardless of the mild hyperthermic treatment. Copper uptake of the tumor was verified by PET/CT imaging following treatment with [⁶⁴Cu]Cu-neocuproine liposomes. Taken together, our results demonstrate the feasibility of targeting a copper nanotoxin that was encapsulated in thermosensitive liposomes containing an excess of copper.

Metal ions and the extracellular matrix in tumor migration

In this review, we explore the roles of divalent metal ions in structure and function within the extracellular matrix (ECM), specifically, their interaction with glycosaminoglycans (GAGs) during tumor progression. Metals and GAGs have been individually associated with physiological and pathological processes, however, their combined activities in regulating cell behavior and ECM remodeling have not been fully explored to date. During tumor progression, divalent metals and GAGs participate in central processes, such as cell migration and angiogenesis, either by modulating cell surface molecules, as well as soluble signaling factors. In addition, studies on metals and polysaccharides interactions have been of great value, as they provide structural information that can be correlated with function. Finally, we believe that understanding how metals are regulated in physiological and pathological conditions is paramount for the development of new treatment strategies, as well as diagnostic and exploratory tools.

Gd(iii)-Pt(iv) theranostic contrast agents for tandem MR imaging and chemotherapy

Pt(iv) prodrugs have emerged as versatile therapeutics for addressing issues regarding off-target toxicity and the chemoresistance of classic Pt(ii) drugs such as cisplatin and carboplatin. There is significant potential for Pt(iv) complexes to be used as theranostic agents, yet there are currently no reported examples of Gd(iii)–Pt(iv) agents for simultaneous MR imaging and chemotherapy. Here we report the synthesis, characterization, and in vitro efficacy of two Gd(iii)–Pt(iv) agents, GP1 and GP2. Both agents are water soluble and stable under extracellularly relevant conditions but are reduced under intracellular conditions. Both are cytotoxic in multiple cancer cell lines, cell permeable, and significantly enhance the T₁-weighted MR contrast of multiple cell lines. Thus, GP1 and GP2 are promising agents for tandem MR imaging and chemotherapy and provide a versatile platform through which future Gd(iii)–Pt(iv) agents can be developed.

The first example of Gd(iii)–Pt(iv) theranostic agents that are intracellularly reduced to provide MR contrast enhancement with simultaneous Pt(ii) chemotherapy.

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.

Water soluble palladium(ii) and platinum(ii) acyclic diaminocarbene complexes: solution behavior, DNA binding, and antiproliferative activity

Water soluble Pd(ii) and Pt(ii)–ADC species synthesized via the metal-mediated coupling of isocyanides and 1,2-diaminobenzene have demonstrated antitumor potential.

Synthesis and anti-proliferative activities of amine capped Pd and Pt macrocycles of 4,4′-dipyridylselenides

Symmetric macrocyclic complexes characterized as dimeric and their oligomeric form in water and the solid state exhibit high in vitro anticancer activities.

Theranostic Lysosomal Targeting Anticancer and Antimetastatic Agents: Half-Sandwich Iridium(III) Rhodamine Complexes

Two rhodamine-modified half-sandwich Ir(III) complexes with the general formula [(Cp^x)Ir(ĈN) Cl] were synthesized and characterized, where Cp^x is 1-biphenyl-2,3,4,5-tetramethylcyclopentadienyl (Cp^xbiph). Both complexes showed potent anticancer activity against A549, HeLa, and HepG2 cancer cells and normal cells, and altered ligands had an effect on proliferation resistance. The complex enters cells through energy dependence, and because of the different ligands, not only could it affect the anticancer ability of the complex but also could affect the degree of complex lysosome targeting, lysosomal damage, and further prove the antiproliferative mechanism of the complex. Excitingly, antimetastatic experiments demonstrated that complex 1 has the ability to block the migration of cancer cells. Furthermore, although the complex did not show a stronger ability to interfere with the coenzyme NAD⁺/NADH pair by transfer hydrogenation, the intracellular reactive oxygen species (ROS) content has shown a marked increase. NF-κB activity is increased by ROS regulation, and the role of ROS-NF-κB signaling pathway further induces apoptosis. Moreover, cell flow experiments also demonstrated that complex 1 blocked the cell cycle in S phase, but the complex did not cause significant changes in the mitochondrial membrane potential.

Biological relevance of interaction of platinum drugs with O-donor ligands

Platinum complexes with S and N-donor small molecule ligands have received much attention with respect to understanding of Pt-protein and Pt-DNA(RNA) interactions in biology. Oxygen-donor ligands have received less attention, partly due to the fact that as a hard Lewis base, oxygen-donor interactions are expected to be less favourable for the soft Lewis acid properties of Pt(II), especially. Yet, it is now clear that for a full understanding of the cellular fate of platinum complexes, a plethora of oxygen-donor interactions are possible, considering extracellular and intracellular concentrations of simple anions in buffer. Further, the importance of the general class of glycans, the third major class of biomolecules after proteins and nucleic acids, contain many specific examples of important biomolecules such as sialic acids and sulphated glycosaminoglycans capable of metal complex interactions. In this contribution we summarise some important kinetic and thermodynamic aspects of platinum-oxygen-donor ligand interactions and their relevance to examples of biomolecular interactions contributing to the overall profile of platinum (and metal complexes in general) biology.

A nano-cocktail of an NIR-II emissive fluorophore and organoplatinum(ii) metallacycle for efficient cancer imaging and therapy

The scarcity of efficient imaging technologies for precise cancer treatment greatly drives the development of new nanotheranostic based platforms that enable both diagnostic and therapeutic functions, together in a single formulation. Owing to the complicated physiological microenvironment, nanosystems designed with the possibility of noninvasive real-time monitoring of therapeutic progression in the second near-infrared channel (NIR-II, 1000-1700 nm) could substantially improve the current cancer therapies. Herein, we design a novel NIR-II theranostic nanoprobe, PSY (size ∼110 nm), by incorporating organoplatinum(ii) metallacycles P1 and an organic NIR-II molecular dye, SY1030, into the FDA-approved polymer Pluronic F127. Preliminary in vitro and in vivo studies suggest that PSY is capable of being internalized into glioma U87MG-cells with no significant internalization in non-cancerous tissues. In addition, it shows excellent photostability and minimal background for real-time monitoring the process of therapy in the NIR-II region. Furthermore, in U87MG xenografts and orthotopic breast tumor, PSY demonstrat significantly improved anticancer efficacy compared to a clinically approved Pt(ii)-based anticancer drug, cisplatin. The engineered nano-cocktail PSY offers a simple strategy for delivering the organoplatinum(ii) macrocycle P1 and NIR-II fluorophore SY1030 as a cocktail of diagnostic and therapeutic functions and highlights its promising capacity for future cancer treatment.

Chemotherapeutic Targets in Osteosarcoma: Insights from Synchrotron-MicroFTIR and Quasi-Elastic Neutron Scattering

This study aimed at the development of improved drugs against human osteosarcoma, which is the most common primary bone tumor in children and teenagers with a low prognosis. New insights into the impact of an unconventional Pd(II) anticancer agent on human osteosarcoma cells were obtained by synchrotron radiation-Fourier transform infrared microspectroscopy and quasi-elastic neutron scattering (QENS) experiments from its effect on the cellular metabolism to its influence on intracellular water, which can be regarded as a potential secondary pharmacological target. Specific infrared biomarkers of drug action were identified, enabling a molecular-level description of variations in cellular biochemistry upon drug exposure. The main changes were detected in the protein and lipid cellular components, namely, in the ratio of unsaturated-to-saturated fatty acids. QENS revealed reduced water mobility within the cytoplasm for drug-treated cells, coupled to a disruption of the hydration layers of biomolecules. Additionally, the chemical and dynamical profiles of osteosarcoma cells were compared to those of metastatic breast cancer cells, revealing distinct dissimilarities that may influence drug activity.

Three Pt-Pt Complexes with Donor-acceptor Feature: Anticancer Activity, DNA Binding Studies and Molecular Docking Simulation

BACKGROUND

Due to their unique properties and potential applications in variety of areas, recently, a special attention is given to the binuclear platinum (II) complexes. They reveal a highly tunable features upon the modification of their cyclometallating and bridging ligands.

OBJECTIVE

The aim of this study was to evaluate the anticancer activity and DNA binding affinity of three binuclear platinum (II) complexes, including ht-[(p-FC₆H₄)Pt(µ-PN)(µ-NP)PtMe₂](CF₃CO₂)(1), ht-[(p- MeC₆H₄)Pt(µ-PN)(μ-NP)Pt(p MeC₆H₄) Me] (CF₃CO₂)(2) and ht-[Pt₂Me₃(µ-PN)2](CF₃CO₂) (3).

METHODS

MTT assay was performed to study the cell viability of Jurkat and MCF-7 lines against synthesized complexes, followed by apoptosis detection experiments. Several spectroscopic methods with molecular docking simulation were also used to investigate the detail of interaction of these platinum complexes with DNA.

RESULTS

Cell viability assay demonstrated a notable level of cytotoxicity for the synthetic platinum complexes. Further studies proved that a pathway of cell signaling initiating the apoptosis might be activated by these complexes, particularly in the case of complexes 1 and 2. The results of both UV-visible and CD measurements showed the significant ability of these complexes to interact with DNA. While fluorescence data revealed that these complexes cannot enter DNA structure by intercalation, molecular docking assessment proved their DNA groove binding ability.

CONCLUSION

The remarkable apoptosis inducing activity of the binuclear platinum complexes 1 and 2 and their considerable interaction with DNA suggest them as the potential antitumor medicines.

Diplatinum(II) Catecholate of Photoactive Boron-Dipyrromethene for Lysosome-Targeted Photodynamic Therapy in Red Light

The binuclear platinum(II) boron-dipyrromethene (BODIPY) complex [{Pt(dach)}₂(μ-Dcrb)] (DP), where dach is 1,2-diaminocyclohexane and H₄Dcrb is a morpholine-conjugated BODIPY-linked dicatechol bridging ligand, was prepared for lysosome organelle targeting and near-IR (NIR) light (600-720 nm) induced photocytotoxic activity. The platinum complex [Pt(dach)(cat)] (CP), where H₂cat is catechol, was synthesized and used as a control complex without bearing the BODIPY unit. The complex DP displayed a band at 660 nm (ε = 2.1 × 10⁴ M^-1 cm^-1) in the red region of the UV-visible spectrum recorded in 10% dimethyl sulfoxide/Dulbecco's Modified Eagle's Medium (DMSO/DMEM, pH 7.2). The complex DP and the BODIPY ligand displayed emission in 10% DMSO-DMEM (pH 7.2) giving an λ_em value of 668 nm (λ_ex = 650 nm) with a Φ_F value of 0.02 for DP and 0.16 for H₄Dcrb (Φ_F, fluorescence quantum yield). Titration experiments using 1,3-diphenylisobenzofuran (DPBF) indicated that the complex DP and H₄Dcrb on irradiation with near-IR light of 600-720 nm generated singlet oxygen (¹O₂) as the ROS (reactive oxygen species). The complex DP showed significant lysosomal localization and remarkable apoptotic photodynamic therapy (PDT) effects, giving half-maximal inhibitory concentration values (IC₅₀) within 0.6-3.4 μM in HeLa cervical cancer, A549 lung cancer, and MDA-MB231 multidrug resistant cancer cells, while being essentially nontoxic in the dark and in the HPL1D immortalized lung epithelial normal cells. The acridine orange assay using A549 cells showed lysosomal membrane permeabilization by the complex DP under near-IR light (600-720 nm). This complex on near-IR light (600-720 nm) activation in A549 cells induced apoptotic cell death, as observed from an Annexin-V FITC assay.