Antitumor Platinum Research Articles

The mechanism of antiproliferative activity of the oxaliplatin pyrophosphate derivative involves its binding to nuclear DNA in cancer cells.

(1R,2R-diaminocyclohexane)(dihydropyrophosphato) platinum(II), also abbreviated as RRD2, belongs to a class of potent antitumor platinum cytostatics called phosphaplatins. Curiously, several published studies have suggested significant mechanistic differences between phosphaplatins and conventional platinum antitumor drugs. Controversial findings have been published regarding the role of RRD2 binding to DNA in the mechanism of its antiproliferative activity in cancer cells. This prompted us to perform detailed studies to confirm or rule out the role of RRD2 binding to DNA in its antiproliferative effect in cancer cells. Here, we show that RRD2 exhibits excellent antiproliferative activity in various cancer cell lines, with IC50 values in the low micromolar or submicromolar range. Moreover, the results of this study demonstrate that DNA lesions caused by RRD2 contribute to killing cancer cells treated with this phosphaplatin derivative. Additionally, our data indicate that RRD2 accumulates in cancer cells but to a lesser extent than cisplatin. On the other hand, the efficiency of cisplatin and RRD2, after they accumulate in cancer cells, in binding to nuclear DNA is similar. Our results also show that RRD2 in the medium, in which the cells were cultured before RRD2 accumulated inside the cells, remained intact. This result is consistent with the view that RRD2 is activated by releasing free pyrophosphate only in the environment of cancer cells, thereby allowing RRD2 to bind to nuclear DNA.

Pt(ii) and Pt(iv) complexes with a major component of royal jelly as innovative antitumor drug candidates

The major and unique fatty acid in Royal Jelly, trans-10-hydroxy-2-decenoic acid, which have anti-tumor, immunomodulatory, and other properties, has been combined with the antitumor platinum moiety of clinically used oxaliplatin.

Novel Platinum(II) and Platinum(IV) Antitumor Agents that Exhibit Potent Cytotoxicity and Selectivity.

A novel platinum(II) complex 47OMESS(II) and its platinum(IV) derivative 47OMESS(IV) were synthesized and characterized. Cytotoxicity studies against mesenchymal cells (MCs) and lung (A549), breast (MDA-MB-231), and melanoma (A375) cancer cells demonstrated 7-20-fold superior activity for both complexes relative to cisplatin. Remarkably, 47OMESS(IV) demonstrated 17-22-fold greater selectivity toward the cancerous cells compared to the non-cancerous MCs. Western blot analysis on A549 cells showed the involvement of the intrinsic apoptotic pathway. Cellular fractionation and uptake experiments in A549 cells using ICP-mass spectrometry (MS) indicated that 47OMESS(II) and 47OMESS(IV) cross the cellular membrane predominantly via active transport mechanisms. The significant improvement in selectivity that is exhibited by 47OMESS(IV) is reported for the first time for this class of complexes.

Assessment of antibacterial activity of vinyltriphenylphosphonium hexabromoplatinate

Introduction. One of the biological effects of platinum compounds is antibacterial action against Gram-positive and Gram-negative bacteria. Thus, some platinum compounds may inhibit the synthesis of DNA, RNA and proteins in Escherichia coli cells.Aim — to study the antibacterial effect of vinyltriphenylphosphonium hexabromoplatinate (VH) against E. coli and Staphylococcus aureus bacteria.Materials and methods. The antibacterial effect of VH was studied by the quantitation of the grown colonies of E. coli strain ATCC 25922 and S. aureus strain ATCC 6538 on a nutrient medium in test (suspension of microorganisms, solution of the test substance) and control (suspension of microorganisms). The significance of differences between the outcomes in test and control groups was estimated by two-sided Fisher's exact test.Results. The minimum inhibitory concentration of VH solution for E. coli strain ATCC 25922 was 14,0625 µg/ml, for S. aureus strain ATCC 6538 — 225 µg/ml.Conclusion. VH exhibits a more pronounced antibacterial effect against E. coli compared to S. aureus — the minimum inhibitory concentration of VH observed for E. coli (14,0625 µg/ml, 11,17 µM) is comparable to the effective concentrations of platinum antitumor compounds — therefore, further studies with this bacterium, including in vivo studies, are promising.

Synthesis, characterization, and antitumor biological evaluation of novel fluorine‐containing platinum (IV) complexes

A series of antitumor platinum (IV) complexes based on ammonia and fluoropyridine carrier groups with biotin and chloride ions as axial groups have been designed and synthesized in this paper. The structures of platinum (IV) complexes were fully characterized by 1H NMR, ESI‐MS, and IR. Such Pt (IV) complexes have certain tumor targeting properties, and the Pt (II) complexes released in the reducing microenvironment could combine with DNA. Compared with cisplatin, complexes S3 and S4 exhibited similar cytotoxicity against SW480, HCT116, and HepG2 cancer cell lines according to in vitro antitumor activity evaluation. Particularly, Complex S2 showed 1.5–3.0 times higher cytotoxicity than cisplatin and picoplatin against selected cell lines. According to the structure–activity relationship, the introduction of fluorine atoms and axial chloride has an important influence on the strong cytotoxic activity of Pt (IV) complex. In addition, the axial biotin molecule increased the targeting of the complex to tumor cells. Overall, the novel fluorine‐containing Pt (IV) complex S2 is an attractive antitumor lead compound with further research value.

Antitumor effectiveness of combination therapy with platinum and hybrid organotin compound on the Lewis epidermoid carcinoma model with metronomic administration.

e15080 Background: The prevalence of lung malignancies in Russia in 2019 was 100.5 per 100,000 population, which is 2.5% more than in the previous year. Drug therapy remains one of the main methods of treatment of malignant lung neoplasms. An urgent task for specialists in experimental pharmacology and oncology is searching for new antitumor compounds. Hybrid organotin compound (3,5-di-tert-butyl-4-hydroxyphenylthiolate)triphenylol) is a promising candidate for antitumor drugs [Milaeva E.R. et al. Novel selective anticancer agents based on Sn and Au complexes. Pure & Applied Chemistry. 2020, 92, 1201-1216]. The combined administration of platinum antitumor drug and an organotin compound will increase the effectiveness of therapy and reduce the general toxic effect on the body. Methods: The study was conducted on C57bl/6 mice (females, n = 48, each cohort contained 12 mice) on the Lewis epidermoid carcinoma model (subcutaneous transplantation) [Frantsiants E.M. et al. Method for Stimulation of Malignant Growth by Chronic Pain in Rat Lungs. Bulletin of Experimental Biology and Medicine. 2020, 169(2), 290–292]. Cisplatin-Teva (CP) and (3,5–di–tert–butyl–4–hydroxyphenylthiolate)triphenylolol) (Me-5) were used as chemotherapeutic agents. Groups of animals were formed as follows: I (experimental) - CP at a dose of 1 mg/kg + Me-5 at a dose of 25 mg/kg; II (comparison group) - CP at a dose of 1 mg/kg; III (comparison) - Me-5 at a dose of 25 mg/kg; IV (control group) - without pharmacological substances. All manipulations were carried out according to the European Convention for ETS 123. The compounds were administered intraperitoneally daily during 10 days. 21 days after the subinoculation of tumor cells all animals were euthanized. The antitumor effect was estimated by the percentage inhibition of tumor growth by weight. Results: The combination of the studied substances has a more pronounced antitumor effect. The percentage of reduction in the mass of the primary focus in group I was 38.1%, in group II - 20.4%, in group III - 12%. The obtained results showed that the percentage of inhibition of tumor growth by weight with a tenfold combined administration of Cisplatin-Teva and Me-5 on the Lewis epidermoid carcinoma model was significantly higher than the previously obtained result when studying the combination of Cisplatin-Teva and Me-5 with a five-fold administration [Dodokhova M.A. et al. Effect of cisplatin and hybrid organotin compound in low doses on the growth and metastasis of lewis epidermoid carcinoma in experiment. Eksperimental'naya i Klinicheskaya Farmakologiya. 2021, 84(8), 32–35], which is 38.1% and 25%, respectively. Conclusions: The research suggests a multifactorial mechanism of action of hybrid organotin compounds.

Design, synthesis and biological evaluation of antitumor platinum(II) agents conjugated with non-steroidal anti-inflammatory drug species

As one of the key features of tumor, inflammation attracts much attention of many researchers for antitumor study, in which non-steroidal anti-inflammatory drugs (NSAIDs) have been widely investigated in anti-inflammatory treatments in cancers. Herein, we report a series of novel platinum(II) complexes derived from conjugation of several NSAIDs derivatives with two antitumor platinum(II) agents. The antitumor inhibitory effects of the synthesized compounds on a number of cancer cell lines were estimated. By taking the advantage of two bioactive moieties, these compounds exhibited stronger antitumor activity than their parent platinum agents, and some appeared to have capability of overcoming cisplatin resistance. Among them, IA-1 showed the best cytotoxicity and even exhibited stronger antitumor activity than cisplatin. Further research indicated that IA-1 induced significant DNA damage and ROS generation, accompanied by high cellular platinum accumulation, resulting in a much higher apoptosis rate than cisplatin in A2780 cells. Moreover, IA-1 was found to inhibit metastasis and invasion of A2780 cells by suppressing the COX-2/JAK2/STAT3 axis. All these results revealed that introduction of NSAIDs species efficiently sensitized cancer cells to the synthetic compounds, proving that NSAIDs can enhance the activity of the platinum(II) agents via inhibiting inflammation in cancer cells.

A [Pt(cis-1,3-diaminocycloalkane)Cl2] analog exhibits hallmarks typical of immunogenic cell death inducers in model cancer cells

The platinum drugs belong to prevailing chemotherapeutics used in the treatment of cancer. At present, however, the search for new anticancer metal-based drugs that operate by the mechanisms distinct from those of the conventional chemotherapeutics is very active. Furthermore, it has been demonstrated that cytotoxic chemotherapy and immunotherapy may exert a highly synergistic anticancer activity. Thus, the development of antitumor platinum and other metal-based drugs that exhibit cytostatic effects and concurrently elicit immunogenic cell death (ICD) has shown promise for cancer treatment. Notably, conventional platinum drug oxaliplatin ([Pt(1R,2R-DACH)(oxalate)], DACH = diaminocyclohexane) is a well-known agent that displays both cytostatic and immune responses. Moreover, it was also demonstrated that even minor derivatization of the unleaving cycloalkyl moiety in oxaliplatin might have a pronounced effect on its immunomodulatory activity. Here, we investigated how replacing the 1R,2R- diaminocyclohexane ring by 1,3-diaminocycloalkane (alkane = butane, pentane, or hexane) affects the ability to evoke secretion of damage-associated molecular patterns characteristic of ICD in model murine colorectal carcinoma cell line CT26. The results indicate that among the investigated [Pt(cis-1,3-diaminocycloalkane)Cl2] complexes, the complex containing the cyclobutyl moiety exhibits the hallmarks typical of ICD inducers. Thus, [Pt(cis-1,3-diaminocyclobutane)Cl2] may expand the spectrum of anticancer chemotherapeutics capable of inducing ICD in cancer cells and might be of interest for further (pre)clinical development.

Reactivity of arsenoplatin complex versus water and thiocyanate: a DFT benchmark study

Seven different density functionals, including GGAs, meta-GGAs, hybrids and range-separated hybrids, and considering Grimme’s empirical dispersion correction (M06-L, M06-2X, PBE0, B3LYP, B3LYP-D3, CAM-B3LYP, ωB97X) have been tested for their performance in the prediction of molecular structures, energies and energy barriers for a class of newly developed antitumor platinum complexes involving main group heavy elements such as arsenic. The calculated structural parameters, energies and energy barriers have been compared to the available experimental data. The results show that range-separated hybrid functionals CAM-B3LYP and ωB97X give good results in predicting both geometrical parameters and isomerization energies and barrier heights and are promising new tools for the theoretical study of novel platinum(II) arsenic compounds.

Thermodynamic Insights by Microscale Thermophoresis into Translesion DNA Synthesis Catalyzed by DNA Polymerases Across a Lesion of Antitumor Platinum-Acridine Complex.

Translesion synthesis (TLS) through DNA adducts of antitumor platinum complexes has been an interesting aspect of DNA synthesis in cells treated with these metal-based drugs because of its correlation to drug sensitivity. We utilized model systems employing a DNA lesion derived from a site-specific monofunctional adduct formed by antitumor [PtCl(en)(L)](NO3)2 (complex AMD, en = ethane-1,2-diamine, L = N-[2-(acridin-9-ylamino)ethyl]-N-methylpropionamidine) at a unique G residue. The catalytic efficiency of TLS DNA polymerases, which differ in their processivity and fidelity for the insertion of correct dCTP, with respect to the other incorrect nucleotides, opposite the adduct of AMD, was investigated. For a deeper understanding of the factors that control the bypass of the site-specific adducts of AMD catalyzed by DNA polymerases, we also used microscale thermophoresis (MST) to measure the thermodynamic changes associated with TLS across a single, site-specific adduct formed in DNA by AMD. The relative catalytic efficiency of the investigated DNA polymerases for the insertion of correct dCTP, with respect to the other incorrect nucleotides, opposite the AMD adduct, was reduced. Nevertheless, incorporation of the correct C opposite the G modified by AMD of the template strand was promoted by an increasing thermodynamic stability of the resulting duplex. The reduced relative efficiency of the investigated DNA polymerases may be a consequence of the DNA intercalation of the acridine moiety of AMD and the size of the adduct. The products of the bypass of this monofunctional lesion produced by AMD and DNA polymerases also resulted from the misincorporation of dNTPs opposite the platinated G residues. The MST analysis suggested that thermodynamic factors may contribute to the forces that governed enhanced incorporation of the incorrect dNTPs by DNA polymerases.

Antitumoral effects of mitochondria-targeting neutral and cationic cis-[bis(1,3-dibenzylimidazol-2-ylidene)Cl(L)]Pt(ii) complexes.

Recently, we opened a synthetic access to antitumoral platinum complexes of the type cis-[(NHC)1(NHC)2PtIICl(L)] which interact with DNA in a way correlated to the complex charge and to the sterical accessibility of the leaving chlorido ligand. We now identified mitochondria rather than nuclei as the cellular target of the neutral dichlorido complex 1 (L = Cl) and the delocalized lipophilic cationic phosphine complex 2 (L = PPh3), both carrying the same cis-bis(1,3-dibenzylimidazol-2-ylidene) ligands. Their uptake into 518A2 melanoma cells was concentration-dependent and distinctly greater for complex 2 which was also more cytotoxic against sensitive cancer cell lines with submicromolar IC50 values. Both complexes interfered strongly with various forms of DNA in vitro, but only complex 2 caused a melanoma cell cycle arrest in G1-phase, setting both apart from the S-phase arresting drug cisplatin. Studies of the intracellular localisation of 1 and 2 were carried out with their alkyne-tagged analogues 6 and 7, which showed identical patterns of cancer cell cytotoxicity, cell cycle interference and effects on mitochondria. Click reactions with 7-hydroxycoumarin azide, colocalisation with Mitotracker™ and confocal microscopy, proved complexes 6 and 7 to accumulate mainly in the mitochondria rather than the nuclei of melanoma cells. Complex 1 and even more so complex 2 reduced the mitochondrial membrane potential and also increased the cellular ROS levels. As a consequence, both complexes caused stress fibre formation in the F-actin cytoskeleton of melanoma cells, most distinctly so complex 2 which also activated the apoptotic cascade mediated by capases-3 and -7.

Platinum(II)-oxalato complexes of seliciclib (CYC202) derivatives show different cellular effects and lesser adverse effects in mouse lymphoma model than cisplatin.

This work presents a deeper pharmacological evaluation of two formerly prepared and characterized, and highly in vitro cytotoxic platinum(II) oxalato complexes [Pt(ox)(L1)2] (1) and [Pt(ox)(L2)2] (2), containing the derivatives of cyclin-dependent kinase inhibitor (CDKi) seliciclib ((R)-roscovitine, CYC202) coordinating as N-donor carrier ligands, i.e., 2-(1-ethyl-2-hydroxyethylamino)-N6-(4-methoxybenzyl)-9-isopropyladenine (L1) and 2-chloro-N6-(2,4-dimethoxybenzyl)-9-isopropyladenine (L2). The positive results of in vitro cytotoxicity screening on human cancer cell lines (HeLa, HOS, A2780, A2780R, G361 and MCF7 with IC50 at low micromolar levels) published previously, motivated us to perform extended preclinical in vitro experiments to reveal the mechanisms associated with the induction of cancer cell death. In addition, the in vivo antitumor activity was evaluated using the mouse lymphocytic leukaemia L1210 model. The obtained results revealed that complex 1 exceeds the antitumor effect of cisplatin (as for the extension of life-span of mice) and shows far less adverse effects as compared to reference drug cisplatin. The in vitro and ex vivo studies of cellular effects and molecular mechanisms of cell death induction showed that the mechanism of action of complex 1 is essentially different from that of cisplatin. The obtained results showed a possible way how to obtain antitumor active platinum(II) oxalato complexes with better therapeutic profile than contemporary used platinum-based therapeutics.

Mechanistic and Structural Basis for Inhibition of Copper Trafficking by Platinum Anticancer Drugs.

Copper (Cu) is required for maturation of cuproenzymes, cell proliferation, and angiogenesis, and its transport entails highly specific protein-protein interactions. In humans, the Cu chaperone Atox1 mediates Cu(I) delivery to P-type ATPases Atp7a and Atp7b (the Menkes and Wilson disease proteins, respectively), which are responsible for Cu release to the secretory pathway and excess Cu efflux. Cu(I) handover is believed to occur through the formation of three-coordinate intermediates where the metal ion is simultaneously linked to Atox1 and to a soluble domain of Cu-ATPases, both sharing a CxxC dithiol motif. The ultrahigh thermodynamic stability of chelating S-donor ligands secures the redox-active and potentially toxic Cu(I) ion, while their kinetic lability allows facile metal transfer. The same CxxC motifs can interact with and mediate the biological response to antitumor platinum drugs, which are among the most used chemotherapeutics. We show that cisplatin and an oxaliplatin analogue can specifically bind to the heterodimeric complex Atox1-Cu(I)-Mnk1 (Mnk1 is the first soluble domain of Atp7a), thus leading to a kinetically stable adduct that has been structurally characterized by solution NMR and X-ray crystallography. Of the two possible binding configurations of the Cu(I) ion in the cage made by the CxxC motifs of the two proteins, one (bidentate Atox1 and monodentate Mnk1) is less stable and more reactive toward cis-Pt(II) compounds, as shown by using mutated proteins. A Cu(I) ion can be retained at the Pt(II) coordination site but can be released to glutathione (a physiological thiol) or to other complexing agents. The Pt(II)-supported heterodimeric complex does not form if Zn(II) is used in place of Cu(I) and transplatin instead of cisplatin. The results indicate that Pt(II) drugs can specifically affect Cu(I) homeostasis by interfering with the rapid exchange of Cu(I) between Atox1 and Cu-ATPases with consequences on cancer cell viability and migration.

Antitumor Platinum(II) Compounds of a Chiral Diamine with Functionalized Cyclobutane-1,1-Dicarboxylates as Leaving Ligands

Antitumor Platinum(II) Compounds of a Chiral Diamine with Functionalized Cyclobutane-1,1-Dicarboxylates as Leaving Ligands

Design and Antitumor Activity of Platinum Complexes

This review presents the main advances in the design of antitumor platinum complexes over the last five years. Particular attention is paid to unconventional antitumor platinum compounds (complexes in the trans configuration, Pt(IV) complexes with S and P donor ligands, multinuclear complexes).

Innovative antitumoral platinum (II) compounds as chemotherapeutic and immunotherapeutic agents

Innovative antitumoral platinum (II) compounds as chemotherapeutic and immunotherapeutic agents

Correction: Simultaneous delivery of olaparib and carboplatin in PEGylated liposomes imparts this drug combination hypersensitivity and selectivity for breast tumor cells.

[This corrects the article DOI: 10.18632/oncotarget.25466.].

Simultaneous delivery of olaparib and carboplatin in PEGylated liposomes imparts this drug combination hypersensitivity and selectivity for breast tumor cells.

Combination regiments involving platinum anticancer drugs and agents with unrelated mechanisms of action are a subject of widespread interest.Here, we show that synergistic toxic action in cancer cells of combinations of antitumor platinum drug carboplatin and effective PARP inhibitor olaparib is considerably improved if these combined drugs are encapsulated into liposomes. Notably, the formation of such nano-formulations, called OLICARB, leads to a marked enhancement of activity in human cancer cell lines (including those resistant to conventional platinum antitumor drugs) and selectivity towards tumor cells. We used immunofluorescence analysis of γH2AX expression and examined DNA damage in cancerous cells treated with the investigated compounds. We find that the synergistic toxic effects in cancer cells of both drugs used in combination, nonencapsulated or embedded in the OLICARB nanoparticles, positively correlates with DNA damage. These results also suggest that the enhancement of the toxic effects of carboplatin by olaparib in cancer cells is a consequence of an accumulation of cytotoxic lesions in DNA due to the inhibition of repair of platinated DNA augmented by the synergistic action of olaparib as an effective PARP inhibitor. Our findings also reveal that the combination of olaparib with carboplatin encapsulated in the OLICARB nanoparticles is particularly effective to inhibit the growth of 3D mammospheres. Collectively, the data provide convincing evidence that the encapsulation of carboplatin and olaparib into liposomal constructs to form the OLICARB nanoparticles may represent the viable approach for the treatment of tumors with the aim to eliminate the possible effects of acquired resistance.

Translesion DNA synthesis across double-base lesions derived from cross-links of an antitumor trinuclear platinum compound: primer extension, conformational and thermodynamic studies.

Polynuclear platinum complexes represent a unique structural class of DNA-binding agents of biological significance. They contain at least two platinum coordinating units bridged by a linker, which means that the formation of double-base lesions (cross-links) in DNA is possible. Here, we show that the lead compound, bifunctional [{trans-PtCl(NH3)2}2μ-trans-Pt(NH3)2{H2N(CH2)6NH2}2]4+ (Triplatin or BBR3464), forms in DNA specific double-base lesions which affect the biophysical and biochemical properties of DNA in a way fundamentally different compared to the analogous double-base lesions formed by two adducts of monofunctional chlorodiethylenetriamineplatinum(ii) chloride (dienPt). We find concomitantly that translesion DNA synthesis by the model A-family polymerase, the exonuclease deficient Klenow fragment, across the double-base lesions derived from the intrastrand CLs of Triplatin was markedly less extensive than that across the two analogous monofunctional adducts of dienPt. Collectively, these data provide convincing support for the hypothesis that the central noncovalent tetraamine platinum linker of Triplatin, capable of hydrogen-bonding and electrostatic interactions with DNA and bridging the two platinum adducts, represents an important factor responsible for the markedly lowered tolerance of DNA double-base adducts of Triplatin by DNA polymerases.

Antitumor platinum(IV) derivatives of carboplatin and the histone deacetylase inhibitor 4-phenylbutyric acid

Five new platinum(IV) derivatives of carboplatin each incorporating the histone deacetylase inhibitor 4-phenylbutyrate in axial position were synthesized and characterized by 1H and 195Pt NMR spectroscopy, electrospray ionization mass spectrometry and elemental analysis, namely cis,trans-[Pt(CBDCA)(NH3)2(PBA)(OH)] (1), cis,trans-[Pt(CBDCA)(NH3)2(PBA)2] (2), cis,trans-[Pt(CBDCA)(NH3)2(PBA)(bz)] (3), cis,trans-[Pt(CBDCA)(NH3)2(PBA)(suc)] (4) and cis,trans-[Pt(CBDCA)(NH3)2)(PBA)(ac)] (5) (PBA=4-phenylbutyrate, CBDCA=1,1-cyclobutane dicarboxylate, bz=benzoate, suc=succinate and ac=acetate). The reduction behavior in the presence of ascorbic acid was studied by high performance liquid chromatography. The cytotoxicity against a panel of human tumor cell lines, histone deacetylase (HDAC) inhibitory activity, cellular accumulation and the ability to induce apoptosis were evaluated. The most effective complex, compound 3, was found to be up to ten times more effective than carboplatin and to decrease cellular basal HDAC activity by approximately 18% in A431 human cervical cancer cells.