Platinum Anticancer Drugs Research Articles

Synthesis, antiproliferative activity in cancer cells and DNA interaction studies of [Pt(cis-1,3-diaminocycloalkane)Cl2] analogs

The search for more effective platinum anticancer drugs has led to the design, synthesis, and preclinical testing of hundreds of new platinum complexes. This search resulted in the recognition and subsequent FDA approval of the third-generation Pt(II) anticancer drug, [Pt(1,2-diaminocyclohexane)(oxalate)], oxaliplatin, as an effective agent in treating colorectal and gastrointestinal cancers. Another promising example of the class of anticancer platinum(II) complexes incorporating the Pt(1,n-diaminocycloalkane) moiety is kiteplatin ([Pt(cis-1,4-DACH)Cl2], DACH = diaminocyclohexane). We report here our progress in evaluating the role of the cycloalkyl moiety in these complexes focusing on the synthesis, characterization, evaluation of the antiproliferative activity in tumor cells and studies of the mechanism of action of new [Pt(cis-1,3-diaminocycloalkane)Cl2] complexes wherein the cis-1,3-diaminocycloalkane group contains the cyclobutyl, cyclopentyl, and cyclohexyl moieties. We demonstrate that [Pt(cis-1,3-DACH)Cl2] destroys cancer cells with greater efficacy than the other two investigated 1,3-diamminocycloalkane derivatives, or cisplatin. Moreover, the investigated [Pt(cis-1,3-diaminocycloalkane)Cl2] complexes show selectivity toward tumor cells relative to non-tumorigenic normal cells. We also performed several mechanistic studies in cell-free media focused on understanding some early steps in the mechanism of antitumor activity of bifunctional platinum(II) complexes. Our data indicate that reactivities of the investigated [Pt(cis-1,3-diaminocycloalkane)Cl2] complexes and cisplatin with glutathione and DNA binding do not correlate with antiproliferative activity of these platinum(II) complexes in cancer cells. In contrast, we show that the higher antiproliferative activity in cancer cells of [Pt(cis-1,3-DACH)Cl2] originates from its highest hydrophobicity and most efficient cellular uptake.

DFT-based reactivity and QSPR studies of platinum (IV) anticancer drugs

In the present work the influence of different axial ligands on reactivity of some selected Pt(IV) complexes with anticancer activities are investigated in both gas and solvent phases using Density Functional Theory (DFT) calculations. Calculated geometries of the complexes are in good agreement with their available X-ray data. The reactivity descriptors such as hardness, chemical potential and electrophilicity are calculated to measure stability and reactive nature of the complexes. It has been interesting to observe that the increase in the number of carbon chain of carboxylato axial ligand has no influence on reactivity of Pt(IV) complexes. Multiple linear regression analyses are performed to build Quantitative Structure Property Relationship (QSPR) models using DFT and molecular mechanics (MM+) based descriptors in gas and solvent phases. Chemical potential is found to be the most significant single descriptor to measure reduction potential of Pt(IV) complexes giving 87% correlation with experimental data. While gas phase derived descriptors are not statistically significant, inclusion of solvent medium increases the correlation of each descriptor with reduction potential and hydrophobicity of the complexes.

Structural Control of Boronic Acid Ligands Enhances Intratumoral Targeting of Sialic Acid To Eradicate Cancer Stem-like Cells.

Aberrant sialylation of cancer cells is emerging as an attractive method for generating effective antitumor strategies. However, as sialic acid (SA) is also present in healthy tissues, systems targeting SA in tumors must be strategically designed to be specifically activated in an intratumoral environment while avoiding systemic interaction. Phenylboronic acid (PBA) and its derivatives have shown potential for developing such smart ligands based on its triggered binding to SA at intratumoral pH. Because the affinity of PBAs against SA can be structurally controlled, the approach may further offer the possibility to enhance tumor targeting by molecularly engineering PBAs. Thus, to demonstrate that the modification of the chemical structure of PBAs can promote tumor targeting, we compared nanomedicines installed with the standard PBA or 5-boronopicolinic acid (5-BPA), which shows an exceptionally high binding affinity to SA in acidic pH. Platinum anticancer drugs were loaded into these nanomedicines and evaluated against orthotopic head and neck tumors, featuring a large fraction of SA-rich cancer stem-like cells (CSCs) that are resistant to platinum drugs. The 5-BPA ligands increased intracellular drug delivery of nanomedicines at intratumoral pH (pH 6.5) and enhanced the accumulation of nanomedicines in tumors to efficaciously eliminate the malignant CSCs, suppress tumor growth, and prolong mice survival. These findings indicate the potential of engineered PBA ligands for developing effective strategies targeting SA in tumors.

A DFT Investigation on Two Proposed Anticancer Platinum(IV) Drugs

In our previous work, we illustrated that tetrachroridoplatinum(IV) complex with dipyridylamine (PtIVdpa) exhibited to be a selective cytotoxic drug, among a series of similar analogues in the in vitro study. In this research, by means of the Becke3LYP DFT functional calculations, PtIVdpa was compared with a known platinum(IV) drug, tetraplatin (PtIVdach), theoretically. The mechanism of two-electron reduction of PtIVdpa was followed thoroughly, in comparison with PtIVdach. The relative Gibbs energies for initial intermediate 5-coordinated [PtIV(dpa)Cl3]+ and also for the last product 4-coordinated [PtII(dpa)Cl2] is lower than those found for PtIVdach. However, since guanosine binds with platinum center, the relative energies become more for compounds with dpa than with dach. It seems the hydrogen bonds play a crucial role in the stability of intermediates and transition states.

Blue moon ensemble simulation of aquation free energy profiles applied to mono and bifunctional platinum anticancer drugs.

Aquation free energy profiles of neutral cisplatin and cationic monofunctional derivatives, including triaminochloroplatinum(II) and cis-diammine(pyridine)chloroplatinum(II), were computed using state of the art thermodynamic integration, for which temperature and solvent were accounted for explicitly using density functional theory-based canonical molecular dynamics (DFT-MD). For all the systems, the "inverse-hydration" where the metal center acts as an acceptor of hydrogen bond has been observed. This has motivated to consider the inversely bonded solvent molecule in the definition of the reaction coordinate required to initiate the constrained DFT-MD trajectories. We found that there exists little difference in free enthalpies of activation, such that these platinum-based anticancer drugs are likely to behave the same way in aqueous media. Detailed analysis of the microsolvation structure of the square-planar complexes, along with the key steps of the aquation mechanism, is discussed.

The Bulk Osteosarcoma and Osteosarcoma Stem Cell Activity of a Necroptosis-Inducing Nickel(II)-Phenanthroline Complex.

We report the anti-osteosarcoma and anti-osteosarcoma stem cell (OSC) properties of a nickel(II) complex, 1. Complex 1 displays similar potency towards bulk osteosarcoma cells and OSCs, in the micromolar range. Notably, 1 displays similar or better OSC potency than the clinically approved platinum(II) anticancer drugs cisplatin and carboplatin in two- and three-dimensional osteosarcoma cell cultures. Mechanistic studies revealed that 1 induces osteosarcoma cell death by necroptosis, an ordered form of necrosis. The nickel(II) complex, 1 triggers necrosome-dependent mitrochondrial membrane depolarisation and propidium iodide uptake. Interestingly, 1 does not evoke necroptosis by elevating intracellular reactive oxygen species (ROS) or hyperactivation of poly ADP ribose polymerase (PARP-1). ROS elevation and PARP-1 activity are traits that have been observed for established necroptosis inducers such as shikonin, TRAIL and glutamate. Thus the necroptosis pathway evoked by 1 is distinct. To the best of our knowledge, this is the first report into the anti-osteosarcoma and anti-OSC properties of a nickel complex.

Non-SMC Condensin I Complex Subunit H (NCAPH) Is Associated with Lymphangiogenesis and Drug Resistance in Oral Squamous Cell Carcinoma

Background: Head and neck cancer, including oral squamous cell carcinoma (OSCC), is the sixth most common malignancy. OSCC has strong invasive ability, and its malignant potential is closely associated with local expansion and lymph node metastasis. Furthermore, local or nodal recurrence worsens OSCC prognosis. In our previous cDNA microarray analysis, non-structural maintenance of chromosome (SMC) condensin I complex subunit H (NCAPH) was identified as an upregulated gene in recurrent OSCC. Although NCAPH has several functions in tumors, its role in OSCC is unknown. Methods: In this study, we examined NCAPH expression in OSCC and performed a functional analysis of human OSCC cells. Results: NCAPH expression was higher in OSCC than in normal oral mucosa. In immunohistochemistry using 142 OSCC specimens, the immunostaining of NCAPH was strongly associated with nodal metastasis and lymphatic infiltration. In multivariate analysis using the Cox proportional hazards model, NCAPH expression was an independent poor prognostic indicator for OSCC. Moreover, NCAPH promoted the migration and adhesion of endothelial cells to OSCC cells and promoted the resistance to platinum anticancer drugs. Conclusions: Our present findings suggest that NCAPH is a novel diagnostic and therapeutic target in OSCC.

The relationship between peripheral neuropathy and efficacy in second-line chemotherapy for unresectable advanced gastric cancer: a prospective observational multicenter study protocol (IVY)

BackgroundPaclitaxel is used in second-line conventional chemotherapies to manage patients with unresectable advanced gastric cancer (GC). Paclitaxel-induced peripheral neuropathy is a known adverse event leading to treatment discontinuation. Additionally, oxaliplatin which causes irreversible peripheral neuropathy is now commonly used in first-line chemotherapy for advanced GC in Japan. Thus, examining the incidence of peripheral neuropathy with paclitaxel after oxaliplatin is necessary to improve the quality of life and outcomes of patients with advanced GC in the second-line treatment setting.MethodsThis prospective observational multicenter study, (which we named IVY study), will evaluate the degree of chemotherapy-induced peripheral neuropathy (CIPN) and the efficacy of second-line chemotherapy for unresectable advanced GC. A patient neurotoxicity questionnaire (PNQ) and the Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity (FACT/GOG-Ntx) will be used to assess CIPN during the second-line treatment. The key eligibility criteria are as follows: 1) unresectable or recurrent GC histologically confirmed to be primary adenocarcinoma of the stomach, 2) age over 20 years, 3) Eastern Cooperative Oncology Group performance status score of 0–2, 4) written informed consent following full study information is provided to the patient, 5) progression or intolerance for first-line chemotherapy comprising fluorinated pyrimidine and platinum anticancer drugs (cisplatin or oxaliplatin) for advanced GC. 6) presence of evaluable lesions as confirmed using a computed tomography (CT) or magnetic resonance imaging. A total of 200 patients is considered to be appropriate for inclusion in this study.DiscussionThe results of this study will provide some information on CIPN with the sequential usage of oxaliplatin as first-line chemotherapy to paclitaxel as second-line chemotherapy in clinical practice.Trial registrationThis trial is registered in the University Hospital Medical Information Network’s Clinical Trials Registry with the registration number UMIN000033376 (Registered 11 July 2018).

Single Cell Electrochemistry – Uptake of Bioinorganic Silver-Based Drugs

Heterogeneity in a cell population is a universal phenomenon in all biological systems including whole tissues, and cell cultures.[1] Intra-tumour heterogeneity has been widely reported for decades from morphological perspectives, whereas phenotypic and genotypic heterogeneity has also been detected.[2] DNA platination is widely assumed as the central mode of action for most platinum anti-cancer drugs. This generalisation on the mode of action for conventional chemotherapy may actually impede effective drug development. Clinical approval for most novel anti-cancer drugs has been denied due to uncertainty in optimal usage, and the modes of action unclear.[3] For a better understanding of variations, from cell to cell, in response to metal-based drugs, single cell analysis is the key. Single cell experiments should provide critical information about the pathway and disease state, which will guide personalised medicine and therapeutic strategies. Electrochemistry is the foremost approach for studying the uptake of metal-based drugs in single cells. This strategy involves positioning a micro or nanoelectrodes inside or near the surface of a single cell for the electrochemical monitoring of individual cellular events.[4]In this work, the aim is to exploit single cell electrochemical analysis, to study the uptake of silver-based bioinorganic drugs and to elucidate the mode of action. Single cell electrochemistry experiments were carried out using the platinum and platinum-black nanoelectrodes on human lung carcinoma (A549) cell lines. Speciation studies of the silver-phenanthroline bioinorganic drugs was examined using stripping voltammetry for metal detection, and the redox behaviour analysis by cyclic voltammetry for in vitro and single cell analysis. [1] Andrew G. Ewing. et al., Anal. Chem. 2019, 91, 1, 588-621 [2] Glenn Deng. et al., Front Cell Dev Biol. 2016, 4: 116. [3] Walter Berger. et al., ESMO Open. 2017, 2(3): e000239. [4] Dechen Jiang. et al., ACS Sens. 2018, 3 (2), 242–250

Glyconanoparticles for Targeted Tumor Therapy of Platinum Anticancer Drug

An important requirement to decrease the side effects of chemotherapy drugs is to develop nanocarriers with precise biological functions. In this work, a set of glyconanoparticles was prepared via self-assembly of amphiphilic glycoblock copolymers for the targeted delivery of a hydrophobic chemotherapy drug. Well-defined glycoblock copolymers that consist of 1,1-di-tert-butyl 3-(2-(metyloyloxy)ethyl)-butane-1,1,3-tricarboxylate (MAETC) together with three different protected-sugar moieties (β-d-glucopyranoside, β-d-mannopyranoside, and β-l-fucopyranoside) were synthesized by using reversible addition-fragmentation chain-transfer polymerization. Copolymers were deprotected and conjugated with the cis-dichlorodiammineplatinum(II) (cis-Pt) anticancer drug. Dynamic light scattering and transmission electron microscopy measurements revealed that cis-Pt-conjugated glyconanoparticles were sufficiently stable under physiological conditions and had diameters of approximately 100 nm with considerably narrow size distributions. They were intracellularly taken up by the breast cancer (MCF-7 and MDA-MB-231), prostate cancer (PC3), renal cancer (769-P), and Chinese hamster ovary cell lines. The PC3 and 769-P cell lines showed a high preference for the glycosylated nanoparticles. Glycoblock copolymers were found nontoxic but showed high cytotoxicity and increased efficacy after conjugation with the cis-Pt anticancer drug. Moreover, in vitro cytotoxicity assays in cancer cell lines demonstrate that cis-Pt-loaded glycopolymer-based nanoparticles have higher cytotoxicity than free cis-Pt. Overall, our results suggest that glyconanoparticles have a great potential to be used as an effective cis-Pt drug carrier for targeted cancer therapy.

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.

Oxaliplatin induces prostaglandin E2 release in vascular endothelial cells.

Oxaliplatin (L-OHP) is known to induce adverse reactions at the injection site, including vascular pain, but the underlying mechanisms have not been clarified. Vascular pain during intravenous L-OHP administration can be inhibited by taking non-steroidal anti-inflammatory drugs (NSAIDs). In this study, we investigated the involvement of the arachidonic acid cascade and prostaglandin (PG) E2 and 15d-PGJ2 in vascular pain sensation during intravenous delivery of L-OHP. Cultured normal human umbilical cord vein endothelial cells (HUVECs) were treated with L-OHP or L-OHP + NSAID flurbiprofen for 2h and analyzed for the release of PGE2 and 15d-PGJ2 into culture supernatant by ELISA. The results showed that L-OHP significantly and dose-dependently increased PGE2 secretion by HUVECs; however, flurbiprofen effectively prevented PGE2 increase. On the other hand, cisplatin, another platinum anticancer drug, did not stimulate PGE2 production. Other PGs, including 15d-PGJ2, 6-keto PGF1α, PGF2α, and PGD2 were not increased by L-OHP or cisplatin. Protein expression analysis revealed that cyclooxygenase 1 and cytoplasmic PGE synthase involved in constitutive PG metabolism were expressed in HUVECs but not affected by L-OHP exposure. This study indicates that L-OHP treatment specifically upregulated PGE2 secretion by vascular endothelial cells, which may contribute to vascular pain, and that NSAIDs can be used to inhibit PGE2 release and attenuate L-OHP-induced hyperalgesia.

Substitution-Inert Polynuclear Platinum Complexes with Dangling Amines: Condensation/Aggregation of Nucleic Acids and Inhibition of DNA-Related Enzymatic Activities.

The substitution-inert polynuclear platinum complexes (SI-PPCs) are now recognized as a distinct subclass of platinum anticancer drugs with high DNA binding affinity. Here, we investigate the effects of SI-PPCs containing dangling amine groups in place of NH3 as ligands to increase the length of the molecule and therefore overall charge and its distribution. The results obtained with the aid of biophysical techniques, such as total intensity light scattering, gel electrophoresis, and atomic force microscopy, show that addition of dangling amine groups considerably augments the ability of SI-PPCs to condense/aggregate nucleic acids. Moreover, this enhanced capability of SI-PPCs correlates with their heightened efficiency to inhibit DNA-related enzymatic activities, such as those connected with DNA transcription, catalysis of DNA relaxation by DNA topoisomerase I, and DNA synthesis catalyzed by Taq DNA polymerase. Thus, the addition of the dangling amine groups resulting in structures of SI-PPCs, which differ so markedly from the derivatives of cisplatin used in the clinic, appears to contribute to the overall biological activity of these molecules.

A Dogma in Doubt: Hydrolysis of Equatorial Ligands of PtIV Complexes under Physiological Conditions.

Due to their high kinetic inertness and consequently reduced side reactions with biomolecules, PtIV complexes are considered to define the future of anticancer platinum drugs. The aqueous stability of a series of biscarboxylato PtIV complexes was studied under physiologically relevant conditions. Unexpectedly and in contrast to the current chemical understanding, especially oxaliplatin and satraplatin complexes underwent fast hydrolysis in equatorial position (even in cell culture medium and serum). Notably, the resulting hydrolysis products strongly differ in their reduction kinetics, a crucial parameter for the activation of PtIV drugs, which also changes the anticancer potential of the compounds in cell culture. The discovery that intact PtIV complexes can hydrolyze at equatorial position contradicts the dogma on the general kinetic inertness of PtIV compounds and needs to be considered in the screening and design for novel platinum‐based anticancer drugs.

An Anticancer PtIV Prodrug That Acts by Mechanisms Involving DNA Damage and Different Epigenetic Effects.

Dual- or multi-action PtIV prodrugs represent a new generation of platinum anticancer drugs. The important property of these PtIV prodrugs is that their antitumor action combines several different mechanisms owing to the presence of biologically active axial ligands. This work describes the synthesis and some biological properties of a "triple-action" prodrug that releases in cancer cells cisplatin and two different epigenetically acting moieties, octanoate and phenylbutyrate. It is demonstrated, with the aid of modern methods of molecular and cellular biology and pharmacology, that the presence of three different functionalities in a single molecule of the PtIV prodrug results in a selective and high potency in tumor cells including those resistant to cisplatin [the IC50 values in the screened malignant cell lines ranged from as low as 9 nm (HCT-116) to 74 nm (MDA-MB-231)]. It is also demonstrated that cellular activation of the PtIV prodrug results in covalent modification of DNA through the release of the platinum moiety accompanied by inhibition of the activity of histone deacetylases caused by phenylbutyrate and by global hypermethylation of DNA by octanoate. Thus, the PtIV prodrug introduced in this study acts as a true "multi-action" prodrug, which is over two orders of magnitude more active than clinically used cisplatin, in both 2D monolayer culture and 3D spheroid cancer cells.

Selectively Oxidized Cellulose with Adjustable Molecular Weight for Controlled Release of Platinum Anticancer Drugs.

The synthesis of selectively oxidized cellulose, 2,3-dicarboxycellulose (DCC), is optimized for preparation of highly oxidized material for biological applications, which includes control over the molecular weight of the product during its synthesis. Conjugates of DCC and cisplatin simultaneously offer a very high drug binding efficiency (>90%) and drug loading capacity (up to 50 wt %), while retaining good aqueous solubility. The adjustable molecular weight of the DCC together with variances in drug feeding ratio allows to optimize cisplatin release profiles from delayed (<2% of cisplatin released during 6 h) to classical burst release with more than 60% of cisplatin released after 24 h. The release rates are also pH-dependent (up to 2 times faster release at pH 5.5 than at pH 7.4), which allows to exploit the acidic nature of tumor microenvironment. Extensive in vitro studies were performed on eight different cell lines for two cisplatin-DCC conjugates with different release profiles. In comparison with free cisplatin, both cisplatin-DCC conjugates demonstrated considerably lower cytotoxicity toward healthy cells. Conjugates with burst release profiles were found more effective against prostate cell lines, while DCC conjugates with slower release were more cytotoxic against ovarian and lung carcinoma cell lines. In vivo studies indicated a significantly longer survival rate, a reduction in tumor volume, and a higher accumulation of platinum in tumors of mice treated with the cisplatin-DCC conjugate in comparison to those treated by free cisplatin.

Design and investigation of photoactivatable platinum(iv) prodrug complexes of cisplatin.

Platinum(iv) carboxylate scaffolds have garnered considerable research interest because they can be engineered to function as prodrugs of clinical platinum(ii) anticancer drugs. These platinum(iv) prodrug complexes are stable and tunable, and activated by reduction to release their cytotoxic platinum(ii) cargo. Here we propose new platinum(iv) prodrug complexes designed to release cisplatin via photoreduction upon UV irradiation. The central strategy is to utilise aryl carboxylate ligands on the axial positions of that platinum(iv) scaffold that confer significant UV absorption and would stabilise carboxyl radical formation, thus favouring homolytic Pt-O bond cleavage. We isolated and identified aryl carboxyl radicals via spin-trapping and showed that the photoreduced platinum species mirror cisplatin reactivity toward DNA bases, thereby validating the efficacy of this approach.

Modular design of nanobody-drug conjugates for targeted-delivery of platinum anticancer drugs with an MRI contrast agent.

A multifunctional nanobody-drug conjugate (NDC) was constructed in this work for the targeted delivery of a platinum prodrug and an MRI contrast agent. The NDC can be specifically internalized into EGFR positive cancer cells, resulting in higher therapeutic effect and lower side-effects relative to cisplatin. The Gd-binding domain enables the in situ detection of the drug distribution in vivo.

The Application of ATR-FTIR Spectroscopy and the Reversible DNA Conformation as a Sensor to Test the Effectiveness of Platinum(II) Anticancer Drugs.

Platinum(II) complexes have been found to be effective against cancer cells. Cisplatin curbs cell replication by interacting with the deoxyribonucleic acid (DNA), reducing cell proliferation and eventually leading to cell death. In order to investigate the ability of platinum complexes to affect cancer cells, two examples from the class of polyfluorophenylorganoamidoplatinum(II) complexes were synthesised and tested on isolated DNA. The two compounds trans-[N,N′-bis(2,3,5,6-tetrafluorophenyl)ethane-1,2-diaminato(1-)](2,3,4,5,6-pentafluorobenzoato)(pyridine)platinum(II) (PFB) and trans-[N,N′-bis(2,3,5,6-tetrafluorophenyl)ethane-1,2-diaminato(1-)](2,4,6-trimethylbenzoato)(pyridine)platinum(II) (TMB) were compared with cisplatin through their reaction with DNA. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy was applied to analyse the interaction of the Pt(II) complexes with DNA in the hydrated, dehydrated and rehydrated states. These were compared with control DNA in acetone/water (PFB, TMB) and isotonic saline (cisplatin) under the same conditions. Principle Component Analysis (PCA) was applied to compare the ATR-FTIR spectra of the untreated control DNA with spectra of PFB and TMB treated DNA samples. Disruptions in the conformation of DNA treated with the Pt(II) complexes upon rehydration were mainly observed by monitoring the position of the IR-band around 1711 cm−1 assigned to the DNA base-stacking vibration. Furthermore, other intensity changes in the phosphodiester bands of DNA at ~1234 cm−1 and 1225 cm−1 and shifts in the dianionic phosphodiester vibration at 966 cm−1 were observed. The isolated double stranded DNA (dsDNA) or single stranded DNA (ssDNA) showed different structural changes when incubated with the studied compounds. PCA confirmed PFB had the most dramatic effect by denaturing both dsDNA and ssDNA. Both compounds, along with cisplatin, induced changes in DNA bands at 1711, 1088, 1051 and 966 cm−1 indicative of DNA conformation changes. The ability to monitor conformational change with infrared spectroscopy paves the way for a sensor to screen for new anticancer therapeutic 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.].