Modifications of DNA by platinum complexes. Relation to resistance of tumors to platinum antitumor drugs

Synthesis, characterization, and cytotoxic properties of mono- and di-nuclear cobalt(ii)-polypyridyl complexes

We report the synthesis and characterisation of mono- and di-nuclear cobalt(ii) complexes (1–3) containing L1, a polypyridyl ligand with pyrazole moieties.

Anticancer activity of osmium(VI) nitrido complexes in patient-derived glioblastoma initiating cells and in vivo mouse models

Glioblastoma is the most prevalent and lethal primary intrinsic brain tumor with a median patient survival of less than two years, even with the optimal standard of care, namely, surgical resection followed by radiotherapy with adjuvant temozolomide chemotherapy. Long-term survival is extremely rare and there is a tremendous need for novel GBM therapies. Following our prior reports on the anticancer activity of osmium(VI) nitrido compounds and their effectiveness against cancer initiating cells, we investigated the efficacy of Os(VI) on GBM initiating cells in vitro and in vivo. Conventional MTT and 3D cytotoxicity assays revealed that patient-derived GBM models were sensitive to cisplatin, TMZ, and two Os(IV) derivatives. Rapid cell death occurred at low micromolar concentrations of the Os(IV) compounds. Cell cycle analysis, Os uptake studies, and cellular distribution experiments provided further insight into the anticancer properties of these compounds, indicating differential uptake for both compounds and a modest G₂/M arrest after treatment. Moreover, in vivo experiments showed a significant increase in survival after a single intracranial chemotherapeutic injection, results that warrant further studies using this approach.

API5 induces cisplatin resistance through FGFR signaling in human cancer cells

Most tumors frequently undergo initial treatment with a chemotherapeutic agent but ultimately develop resistance, which limits the success of chemotherapies. As cisplatin exerts a high therapeutic effect in a variety of cancer types, it is often used in diverse strategies, such as neoadjuvant, adjuvant and combination chemotherapies. However, cisplatin resistance has often manifested regardless of cancer type, and it represents an unmet clinical need. Since we found that API5 expression was positively correlated with chemotherapy resistance in several specimens from patients with cervical cancer, we decided to investigate whether API5 is involved in the development of resistance after chemotherapy and to explore whether targeting API5 or its downstream effectors can reverse chemo-resistance. For this purpose, cisplatin-resistant cells (CaSki P3 CR) were established using three rounds of in vivo selection with cisplatin in a xenografted mouse. In the CaSki P3 CR cells, we observed that API5 acted as a chemo-resistant factor by rendering cancer cells resistant to cisplatin-induced apoptosis. Mechanistic investigations revealed that API5 mediated chemo-resistance by activating FGFR1 signaling, which led to Bim degradation. Importantly, FGFR1 inhibition using either an siRNA or a specific inhibitor disrupted cisplatin resistance in various types of API5^high cancer cells in an in vitro cell culture system as well as in an in vivo xenograft model. Thus, our results demonstrated that API5 promotes chemo-resistance and that targeting either API5 or its downstream FGFR1 effectors can sensitize chemo-refractory cancers.

TIMELESS confers cisplatin resistance in nasopharyngeal carcinoma by activating the Wnt/β-catenin signaling pathway and promoting the epithelial mesenchymal transition

This study investigated the expression, clinicopathological significance and mechanism of action of TIMELESS, a mammalian homolog of a Drosophila circadian rhythm gene, in nasopharyngeal carcinoma. Quantitative real-time PCR, western blotting and immunohistochemistry revealed TIMELESS was upregulated in NPC cell lines (n = 8 vs. NP69 cells), and freshly-frozen (n = 6) and paraffin-embedded human NPC specimens (n = 108 vs. normal samples/non-tumor cells). TIMELESS expression was associated with T category (P = 0.002), N category (P = 0.001), clinical stage (P < 0.001), metastasis (P = 0.047), vital status (P = 0.013) and serum Epstein-Barr DNA (P = 0.005). High TIMELESS expression was associated with poorer overall survival (80.7% vs. 95.9%; P = 0.004) and progression free survival (68.1% vs. 88.0%; P = 0.005). Univariate and multivariate analysis revealed TIMELESS was an independent prognostic factor for overall survival and progression free survival. Stable ectopic overexpression of TIMELESS in NPC cell lines conferred resistance to cisplatin-induced apoptosis in vitro and in vivo, promoted an epithelial-to-mesenchymal transition phenotype, and activated the Wnt/β-catenin pathway and downstream gene transcription; knockdown of TIMELESS had the opposite effects. TIMELESS may play a role in the development of NPC and could represent a valuable prognostic factor and potential therapeutic target.

Cytotoxic (salen)ruthenium(iii) anticancer complexes exhibit different modes of cell death directed by axial ligands

A cancer-cell selective bis(guanidine)-ruthenium(iii) complex induces apoptosis, whereas its amidine analogue effectively kills cancer cells through paraptosis pathways.

Two novel series of (salen)ruthenium(iii) complexes bearing guanidine and amidine axial ligands were synthesized, characterized, and evaluated for anticancer activity. In vitro cytotoxicity tests demonstrate that these complexes are cytotoxic against various cancer cell lines and the leading complexes have remarkable cancer-cell selectivity. A detailed study of the guanidine complex 7 and the amidine complex 13 reveals two distinguished modes of action. Complex 7 weakly binds to DNA and induces DNA damage, cell cycle arrest, and typical apoptosis pathways in MCF-7 cells. In contrast, complex 13 induces paraptosis-like cell death hallmarked by massive vacuole formation, mitochondrial swelling, and ER stress, resulting in significant cytotoxicity against human breast cancer cells. Our results provide an extraordinary example of tuning the mechanism of action of (salen)ruthenium(iii) anticancer complexes by modifying the structure of the axial ligands.

Platinum nanoparticles induce damage to DNA and inhibit DNA replication

Sparsely tested group of platinum nanoparticles (PtNPs) may have a comparable effect as complex platinum compounds. The aim of this study was to observe the effect of PtNPs in in vitro amplification of DNA fragment of phage λ, on the bacterial cultures (Staphylococcus aureus), human foreskin fibroblasts and erythrocytes. In vitro synthesized PtNPs were characterized by dynamic light scattering (PtNPs size range 4.8-11.7 nm), zeta potential measurements (-15 mV at pH 7.4), X-ray fluorescence, UV/vis spectrophotometry and atomic absorption spectrometry. The PtNPs inhibited the DNA replication and affected the secondary structure of DNA at higher concentrations, which was confirmed by polymerase chain reaction, DNA sequencing and DNA denaturation experiments. Further, cisplatin (CisPt), as traditional chemotherapy agent, was used in all parallel experiments. Moreover, the encapsulation of PtNPs in liposomes (LipoPtNPs) caused an approximately 2.4x higher of DNA damage in comparison with CisPt, LipoCisPt and PtNPs. The encapsulation of PtNPs in liposomes also increased their antibacterial, cytostatic and cytotoxic effect, which was determined by the method of growth curves on S. aureus and HFF cells. In addition, both the bare and encapsulated PtNPs caused lower oxidative stress (determined by GSH/GSSG ratio) in the human erythrocytes compared to the bare and encapsulated CisPt. CisPt was used in all parallel experiments as traditional chemotherapy agent.

Modulatory effect of curcumin against genotoxicity and oxidative stress induced by cisplatin and methotrexate in male mice

The use of dietary antioxidants to modulate the toxic side effects induced by the anticancer drugs used in chemotherapy is currently eliciting considerable interest. This study was undertaken to investigate the possible protective role of the antioxidant curcumin (CMN) against genotoxicity, cytotoxicity and oxidative stress induced by cisplatin and methotrexate. Male mice were administered CMN orally in the dosages of 60, 90, and 120 mg/kg for three consecutive days before a single intraperitoneal injection of either cisplatin (6.5 mg/kg) or methotrexate (10 mg/kg). Animals were sacrificed 24 h after treatment with the used anticancer drugs. The protective role of CMN against the genotoxic and cytotoxic effects of the tested anticancer drugs was evaluated by using micronucleus and comet assay. The oxidative stress induced by the two anticancer drugs was assessed by determining malondialdehyde and reduced glutathione levels in kidney tissues. The results indicated that CMN pretreatment at the tested doses reduced the incidence of micronuclei and DNA damage induced by cisplatin and methotrexate. Moreover, malondialdhyde level was significantly decreased while glutathione level was significantly increased in CMN pretreated groups compared with cisplatin- and methotrexate-treated groups. This protective effect of CMN could be attributed to its ability to scavenge reactive oxygen species.

Impact of the Pd2Spermine Chelate on Osteosarcoma Metabolism: An NMR Metabolomics Study

A metabolomics study of Pd₂Spermine(Spm) on osteosarcoma MG-63 and osteoblastic HOb cells is presented to assess the impact of the potential palladium drug on cell metabolism compared with cisplatin (cDDP). Despite its higher cytotoxicity, Pd₂Spm induced lower (and reversible) metabolic impact on MG-63 cells and the absence of apoptosis; conversely, it induced significant deviations in osteoblastic amino acid metabolism. However, when in combination with doxorubicin and methotrexate, Pd₂Spm induced strong metabolic deviations on lipids, choline compounds, amino acids, nucleotides, and compounds related to antioxidative mechanisms (e.g., glutathione, inositol, hypoxanthine), similarly to the cDDP cocktail. Synergetic effects included triggering of lipid biosynthesis by Pd₂Spm in the presence of doxorubicin (and reinforced by methotrexate) and changes in the glycosylation substrate uridine diphosphate acetylgalactosamine and methionine and serine metabolisms. This work provides promising results related to the impact of Pd₂Spm on osteosarcoma cellular metabolism, particularly in drug combination protocols. Lipid metabolism, glycosylation, and amino acid metabolisms emerge as relevant features for targeted studies to further understand a potential anticancer mechanism of combined Pd₂Spm.

Combination of ruthenium(II)-arene complex [Ru(η6-p-cymene)Cl2(pta)] (RAPTA-C) and the epidermal growth factor receptor inhibitor erlotinib results in efficient angiostatic and antitumor activity

Ruthenium-based compounds show strong potential as anti-cancer drugs and are being investigated as alternatives to other well-established metal-based chemotherapeutics. The organometallic compound [Ru(η6-p-cymene)Cl2(pta)], where pta = 1,3,5-triaza-7-phosphaadamantane (RAPTA-C) exhibits broad acting anti-tumor efficacy with intrinsic angiostatic activity. In the search for an optimal anti-angiogenesis drug combination, we identified synergistic potential between RAPTA-C and the epidermal growth factor receptor (EGFR) inhibitor, erlotinib. This drug combination results in strong synergistic inhibition of cell viability in human endothelial (ECRF24 and HUVEC) and human ovarian carcinoma (A2780 and A2780cisR) cells. Additionally, erlotinib significantly enhances the cellular uptake of RAPTA-C relative to treatment with RAPTA-C alone in human ovarian carcinoma cells, but not endothelial cells. Drug combinations induce the formation of chromosome bridges that persist after mitotic exit and delay abscission in A2780 and A2780cisR, therefore suggesting initiation of cellular senescence. The therapeutic potential of these compounds and their combination is further validated in vivo on A2780 tumors grown on the chicken chorioallantoic membrane (CAM) model, and in a preclinical model in nude mice. Immunohistochemical analysis confirms effective anti-angiogenic and anti-proliferative activity in vivo, based on a significant reduction of microvascular density and a decrease in proliferating cells.

Heteroleptic mononuclear compounds of ruthenium(ii): synthesis, structural analyses, in vitro antitumor activity and in vivo toxicity on zebrafish embryos

The limitations of platinum complexes in cancer treatment have motivated the extensive investigation into other metal complexes such as ruthenium. We herein present the synthesis and characterization of a new family of ruthenium compounds 1a-5a with the general formula [Ru(bipy)₂L][CF₃SO₃]₂ (bipy = 2,2'-bipyridine; L = bidentate ligand: N,N; N,P; P,P; P,As) which have been characterized by elemental analysis, ES-MS, ¹H and ³¹P-{¹H} NMR, FTIR and conductivity measurements. The molecular structures of four Ru(ii) complexes were determined by single crystal X-ray diffraction. All compounds displayed moderate cytotoxic activity in vitro against human A2780 ovarian, MCF7 breast and HCT116 colorectal tumor cells. Compound 5a was the most cytotoxic compound against A2780 and MCF7 tumor cells with an IC₅₀ of 4.75 ± 2.82 μM and 20.02 ± 1.46 μM, respectively. The compounds showed no cytotoxic effect on normal human primary fibroblasts but rather considerable selectivity for A2780, MCF7 and HCT116 tumor cells. All compounds induce apoptosis and autophagy in A2780 ovarian carcinoma cells and some nuclear DNA fragmentation. All compounds interact with CT-DNA with intrinsic binding constants in the order 1a > 4a > 2a > 3a > 5a. The observed hyperchromic effect may be due to the electrostatic interaction between positively charged cations and the negatively charged phosphate backbone at the periphery of the double helix-CT-DNA. Interestingly, compound 1a shows a concentration dependent DNA double strand cleavage. In addition in vivo toxicity has been evaluated on zebrafish embryos unveiling the differential toxicity between the compounds, with LC₅₀ ranging from 8.67 mg L^-1 for compound 1a to 170.30 mg L^-1 for compound 2a.

Base-Resolution Analysis of Cisplatin-DNA Adducts at the Genome Scale

Cisplatin, one of the most widely used anticancer drugs, crosslinks DNA and ultimately induces cell death. However, the genomic pattern of cisplatin-DNA adducts has remained unknown owing to the lack of a reliable and sensitive genome-wide method. Herein we present "cisplatin-seq" to identify genome-wide cisplatin crosslinking sites at base resolution. Cisplatin-seq reveals that mitochondrial DNA is a preferred target of cisplatin. For nuclear genomes, cisplatin-DNA adducts are enriched within promoters and regions harboring transcription termination sites. While the density of GG dinucleotides determines the initial crosslinking of cisplatin, binding of proteins to the genome largely contributes to the accumulative pattern of cisplatin-DNA adducts.

Biological evaluation of dimethylpyridine-platinum complexes with potent antiproliferative activity

This study investigates the effect of three new platinum complexes: Pt2(2,4-dimethylpyridine)4(berenil)2 (Pt14), Pt2(3,4-dimethylpyridine)4(berenil)2 (Pt15) and Pt2(3,5-dimethylpyridine)4(berenil)2 (Pt16) on growth and viability of breast cancer cells and their putative mechanism(s) of cytotoxicity. Cytotoxicity was measured with MTT assay and inhibition of [3H]thymidine incorporation into DNA in both breast cancer cells. Results revealed that Pt14-Pt16 exhibit substantially greater cytotoxicity than cisplatin against MCF-7 and MDA-MB-231 breast cancer cells. In the case of human skin fibroblast cell, cytotoxicity assays demonstrated that these compounds are less toxic to normal cells than cisplatin. In addition, the effects of Pt14-Pt16 are investigated using the flow cytometry assessment of annexin V binding, analysis of mitochondrial potential, markers of apoptosis such as caspase-3, caspase-8, caspase-9, caspase-10 and defragmentation of DNA by TUNEL assay. These results indicate that Pt14-Pt16 induce apoptosis by the mitochondrial and external pathway.

Effects of histidin-2-ylidene vs. imidazol-2-ylidene ligands on the anticancer and antivascular activity of complexes of ruthenium, iridium, platinum, and gold

Couples of N-heterocyclic carbene complexes of ruthenium, iridium, platinum, and gold, each differing only in the carbene ligand being either 1,3-dimethylimidazol-2-ylidene (IM) or 1,3-dimethyl-N-boc-O-methylhistidin-2-ylidene (HIS), were assessed for their antiproliferative effect on seven cancer cell lines, their interaction with DNA, their cell cycle interference, and their vascular disrupting properties. In MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays only the platinum complexes were cytotoxic at single-digit micromolar IC₅₀ concentrations with the (HIS)Pt complex being on average twice as active as the (IM)Pt complex. The former was highly efficacious against cisplatin-resistant HT-29 colon carcinoma cells where the latter had no effect. Both Pt complexes were accumulated by cancer cells and bound to double-helical DNA equally well. Only the (HIS)Pt complex modified the electrophoretic mobility of circular DNA in vitro due to the HIS ligand causing greater morphological changes to the DNA. Both platinum complexes induced accumulation of 518A2 melanoma cells in G2/M and S phase of the cell cycle. A disruption of blood vessels in the chorioallantoic membrane of fertilized chicken eggs was observed for both platinum complexes and the (IM)gold complex. The (HIS)platinum complex was as active as cisplatin in tumor xenografted mice while being tolerated better. We found that the HIS ligand may augment the cytotoxicity of certain antitumoral metal fragments in two ways: by acting as a transmembrane carrier increasing the cellular accumulation of the complex, and by initiating a pronounced distortion and unwinding of DNA. We identified a new (HIS)platinum complex which was highly cytotoxic against cancer cells including cisplatin-resistant ones.

C-Jun N-terminal kinase signalling pathway in response to cisplatin

Cisplatin (cis diamminedichloroplatinum II, cDDP) is one of the most effective cancer chemotherapeutic agents and is used in the treatment of many types of human malignancies. However, inherent tumour resistance is a major barrier to effective cisplatin therapy. So far, the mechanism of cDDP resistance has not been well defined. In general, cisplatin is considered to be a cytotoxic drug, for damaging DNA and inhibiting DNA synthesis, resulting in apoptosis via the mitochondrial death pathway or plasma membrane disruption. cDDP-induced DNA damage triggers signalling pathways that will eventually decide between cell life and death. As a member of the mitogen-activated protein kinases family, c-Jun N-terminal kinase (JNK) is a signalling pathway in response to extracellular stimuli, especially drug treatment, to modify the activity of numerous proteins locating in the mitochondria or the nucleus. Recent studies suggest that JNK signalling pathway plays a major role in deciding the fate of the cell and inducing resistance to cDDP-induced apoptosis in human tumours. c-Jun N-terminal kinase regulates several important cellular functions including cell proliferation, differentiation, survival and apoptosis while activating and inhibiting substrates for phosphorylation transcription factors (c-Jun, ATF2: Activating transcription factor 2, p53 and so on), which subsequently induce pro-apoptosis and pro-survival factors expression. Therefore, it is suggested that JNK signal pathway is a double-edged sword in cDDP treatment, simultaneously being a significant pro-apoptosis factor but also being associated with increased resistance to cisplatin-based chemotherapy. This review focuses on current knowledge concerning the role of JNK in cell response to cDDP, as well as their role in cisplatin resistance.

Acute toxicity evaluation of a thiazolo arene ruthenium (II) complex in rats

Recently, a series of thiazolo arene ruthenium complexes were found to be highly cytotoxic in vitro, on both cisplatin-sensitive and cisplatin-resistant ovarian cancer cells. The most active compound of the series, [(η(6)-p-cymene)Ru(L)Cl]Cl (L = 1-(2-(2-(3-chlorobenzylidene)hydrazinyl)-4-methylthiazol-5-yl)ethanone), was selected for an in vivo study in order to assess its safety profile. The ruthenium complex was administered to female Crl:WI rats orally, by gastric intubation and intraperitoneal injection. The hematological parameters and the histopathological changes in liver, kidneys, spleen and brain were investigated after a 14-days treatment. The substance was very well tolerated orally, with a LD50 value of over 2000 mg/kg body weight. Symptoms were observed only in the first day after intraperitoneal administration of the highest dose, with a LD50 value between 300 and 2000 mg/kg bw. The hematological profile was not modified at any of the tested doses, after both oral and intraperitoneal acute administration. Structural modifications (moderate lymphocytolysis) were identified only in the spleen at the highest tested dose. In conclusion, the thiazolo arene ruthenium complex was very well tolerated orally and had a low acute toxicity after intraperitoneal administration in Crl:WI rats The results justify further investigation to determine the in vivo therapeutic potential of this promising ruthenium complex.

Advances in cobalt complexes as anticancer agents

The evolution of resistance to traditional platinum-based anticancer drugs has compelled researchers to investigate the cytostatic properties of alternative transition metal-based compounds. The anticancer potential of cobalt complexes has been extensively studied over the last three decades, and much time has been devoted to understanding their mechanisms of action. This perspective catalogues the development of antiproliferative cobalt complexes, and provides an in depth analysis of their mode of action. Early studies on simple cobalt coordination complexes, Schiff base complexes, and cobalt-carbonyl clusters will be documented. The physiologically relevant redox properties of cobalt will be highlighted and the role this plays in the preparation of hypoxia selective prodrugs and imaging agents will be discussed. The use of cobalt-containing cobalamin as a cancer specific delivery agent for cytotoxins will also be described. The work summarised in this perspective shows that the biochemical and biophysical properties of cobalt-containing compounds can be fine-tuned to produce new generations of anticancer agents with clinically relevant efficacies.

Cytotoxic trans-platinum(II) complex with 3-hydroxymethylpyridine: Synthesis, X-ray structure and biological activity evaluation

To assess the potential cytostatic properties of Pt(II) complexes with 3-hydroxymethylpyridine (3-hmpy) as the only carrier ligand, novel cis-[PtCl2(3-hmpy)2] (1) and trans-[PtCl2(3-hmpy)2] (2) have been prepared. Elemental analysis, FTIR spectroscopy, multinuclear NMR spectroscopy and X-ray crystallography were used to determine their structures. Based on the results obtained with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay and clonogenic assay on T24 human bladder carcinoma cells (T24), the most potent compound 2 was further tested for cytotoxicity in human ovarian carcinoma cell lines - cisplatin sensitive (IGROV 1) and its resistant subclone (IGROV 1/RDDP). The cytotoxicity of compound 2 in IGROV 1/RDDP is comparable to cisplatin. Furthermore, compound 2 induced severe conformational changes in plasmid DNA, which resulted in a delayed onset of apoptosis in T24 cells, and higher amounts of Pt in tumours and serum compared to cisplatin. In addition, in vivo antitumour effectiveness was comparable to that of cisplatin with a smaller reduction of animals' body weight, thus demonstrating that it is a promising transplatin analogue which deserves further studies.

Novel dinuclear platinum(II) complexes targets NFkappaB signaling pathway to induce apoptosis and inhibit metabolism of MCF-7 breast cancer cells

Four novel dinuclear platinum(II) complexes of formula [Pt2L4(berenil)2]Cl4 (Pt1-Pt4) where L is piperazine (Pt1), 4-picoline (Pt2), 3-picoline (Pt3) or isopropylamine (Pt4) were compared to cisplatin in respect to collagen biosynthesis, beta1- integrin receptor, IGF-I receptor, phosphorylated MAP-kinases (ERK1/ERK2 and p38), phosphorylated Akt kinase expression and appearance of apoptosis in MCF-7 breast cancer cells. It was found that Pt1-Pt4 were more active inhibitor of collagen biosynthesis than cisplatin. The expression of IGF-I and beta1 integrin receptor, as well as phosphorylated MAPK, (ERK1 and ERK2 and p38) was significantly increased in cells incubated for 24 h with 20 muM Pt1-Pt4 compared to the control, not treated cells. The phenomenon was related to the increase expresion of NFkappaB by Pt1-Pt4 as shown by Western immunoblot analysis. Experiments made with annexin V-FITC and detection of apoptosis by a fluorescent microscopy assay revealed that novel dinuclear platinum(II) complexes (Pt1-Pt4) inhibited the proliferation of MCF-7 breast cancer cells by increasing the number of apoptotic and necrotic cells.

4-Azidobenzyl ferrocenylcarbamate as an anticancer prodrug activated under reductive conditions

Aminoferrocene-based prodrugs are activated in the presence of cancer-specific amounts of reactive oxygen species, e.g. H2O2, with the formation of products of two types: Fe-containing complexes, which catalyze generation of HO and O2(-), and quinone methides, which alkylate glutathione and inhibit the antioxidative system of the cell. Both processes act synergistically by increasing the oxidative stress in cancer cells thereby leading to their death. However, in the activation step including the cleavage of a B-C bond one molecule of H2O2 is consumed that counteracts the desired effect of the products released from aminoferrocenes. We replaced an H2O2-sensitive trigger in original prodrugs with an azide group. This trigger is slowly reduced in the presence of glutathione with the formation of an unstable arylamine intermediate, which decomposes with the release of iron ions and iminoquinone methides. These products induce strong oxidative stress in cells as we confirmed using 2',7'-dichlorodihydrofluorescin diacetate reagent in combination with flow cytometry. In this case the activation process does not consume H2O2. Correspondingly, we observed that the azide-containing prodrug is substantially more toxic towards human promyelocytic leukemia cell line HL-60 (IC50=27±4μM) than its H2O2-responsive analogue (IC50>50μM).

Metal-based drugs that break the rules

Cisplatin and other platinum compounds have had a huge impact in the treatment of cancers and are applied in the majority of anticancer chemotherapeutic regimens. The success of these compounds has biased the approaches used to discover new metal-based anticancer drugs. In this perspective we highlight compounds that are apparently incompatible with the more classical (platinum-derived) concepts employed in the development of metal-based anticancer drugs, with respect to both compound design and the approaches used to validate their utility. Possible design approaches for the future are also suggested.

Exploring saccharinate-tetrazoles as selective Cu(ii) ligands: structure, magnetic properties and cytotoxicity of copper(ii) complexes based on 5-(3-aminosaccharyl)-tetrazoles

Saccharinate-tetrazolesTSand2MTSbind selectively to copper(ii). The resulting copper complexes have shown a huge increase in thein vitrocytotoxicity against hepatic carcinoma cells (HepG2) compared to the corresponding nontoxic free ligands.

Anticancer potential of a photoactivated transplatin derivative containing the methylazaindole ligand mediated by ROS generation and DNA cleavage

Photoinduced DNA damage by trans-[PtCl₂(NH₃)(1-methyl-7-azaindole)] is related to its photocytotoxic activity.

DNA damage-induced apoptosis suppressor (DDIAS), a novel target of NFATc1, is associated with cisplatin resistance in lung cancer

In a previous study, we reported that DNA damage induced apoptosis suppressor (DDIAS; hNoxin), a human homolog of mouse Noxin, functions as an anti-apoptotic protein in response to DNA repair. Here we reveal that DDIAS is a target gene of nuclear factor of activated T cells 2 (NFATc1) and is associated with cisplatin resistance in lung cancer cells. In the DDIAS promoter analysis, we found that NFATc1 activated the transcription of DDIAS through binding to NFAT consensus sequences in the DDIAS promoter. In addition, tissue array immunostaining revealed a correlation between DDIAS and NFATc1 expression in human lung tumors. NFATc1 knockdown or treatment with the NFAT inhibitor cyclosporine A induced apoptosis and led to growth inhibition of lung cancer cells, indicating the functional relevance of both the proteins. In contrast, DDIAS overexpression overcame this NFATc1 knockdown-induced growth inhibition, supporting the cancer-specific role of DDIAS as a target gene of NFATc1. NFATc1 or DDIAS inhibition clearly enhanced apoptosis induced by cisplatin in NCI-H1703 and A549 cells. Conversely, DDIAS overexpression rescued NCI-H1703 cells from cisplatin-mediated cell death and caspase-3/7 activation. These results suggest that NFATc1-induced DDIAS expression contributes to cisplatin resistance, and targeting DDIAS or NFATc1 impairs the mechanism regulating cisplatin resistance in lung cancer cells. Taken together, DDIAS is a target of NFATc1 and is associated with cisplatin resistance in lung cancer cells.